It probably comes as no surprise to anyone reading this that science illiteracy is rampant in the US. Over a quarter of the population doesn’t believe in evolution in spite of an extensive fossil record, solid scientific theory, and observations of evolution in both the laboratory and the field. This is a classic example, but does it really matter whether or not Americans believe in evolution? Is this really a knowledge deficit that will bring the nation to its knees? Well…maybe.

Let’s think about medicine – and how much of medical testing is performed on animals because of the ethics of trying out new drugs or new surgical procedures on human subjects. One of the reasons that animal testing works is that we have remarkable similarities to some species of animals – and we are more similar to animals that we are evolutionarily closer to. Do we want our medical researchers to be taught that humans were miraculously created unique from the animals, or do we want them to understand the evolutionary rationale for the work in which they are engaged?

Of course, evolution takes place right in front of our eyes, and in a way that has very real implications for all of us – the evolution of drug-resistant bacteria in our hospitals and in our livestock farms. The development of drug-resistant and multi-drug-resistant bacteria is well-documented in the scientific literature, the medical literature, and in the popular literature. Multi-drug resistant microbes are a huge threat – according to the World Health Organization multi-drug resistant tuberculosis alone kills over 150,000 people annually, and deaths from multi-drug resistant microbes in the US and elsewhere in the world have risen significantly over the last decade or so. Everyone who enters a hospital is at greater risk of catching a fatal infection because of the rise of multi-drug resistant germs and the reason for this is the evolution of antibiotic resistance among microbes exposed to human antibiotics on the farm, in hospitals, and elsewhere. But how do we explain this to a population that increasingly denies that evolution of any sort occurs?

Genetically modified organisms (GMOs) are another area in which people are all too willing to vent opinions without an understanding of the underlying science. Simply throwing around terms like “frankenfood” and “the precautionary principle” as reasons to avoid genetically modified food is one thing, but few – if any – of those shunning these foods have any real understanding of what a gene is, let alone what is involved in splicing them from one organism into another. I can’t help but wonder how many anti-GMO advocates realize that there are hundreds or thousands of genes in their bodies that are identical to genes found in lizards, fish, and even bacteria. Consider an analogy – the basic tasks involved in running most businesses are the same, regardless of what the business happens to be or the size of the company. Every company has to deal with the basics – paying rent and utilities, managing a payroll, taking orders, scheduling workers, and so forth – and General Electric handles these tasks in much the same manner as I did when I worked as an independent consultant. Similarly, every cell has a certain amount of “housekeeping” that has to take place, and a great deal of this is done the same way – using the same genes – regardless of the organism.

In my own field of expertise for example, there are a bunch of DNA repair genes in each of my cells that are identical to those in the E. coli in my intestines. Similarly, each of my cells produces energy using a molecule called ATP – the genes that cause this process to occur are the same in humans as they are in every other organism that makes energy in this manner – all but a handful of bacteria. Seen from this perspective – realizing the immense amount of genetic overlap between humans and so many other creatures – genetically modified foods might not seem quite as risky. But lacking this level of understanding, the case against GMOs might seem far stronger than is really the case. This is important – not only are genetically modified crops extensively farmed throughout the world, but GMOs hold out the promise of feeding and nourishing hundreds of millions of the world’s hungry – if we decide to ban all GMOs then we are condemning many of these hundreds of millions to lives of malnutrition and hunger and early death; surely this decision should be made based on a sound understanding of the science involved rather than a gut feeling that messing with nature is wrong.

Statistics is yet another area that is willfully overlooked by too many. I have to admit that my college statistics class was not the most scintillating I’ve taken – but what I learned there more than made up for the lack of excitement. Statistics is what helps us to understand what the numbers we are deluged with actually mean, and it is what helps us to make sense of the world around us. And if properly used they also help us to look past the hype and to see the underlying structure. Risk is a statistical phenomenon – we use statistics to help us to understand whether it’s safer to drive or to fly from New York to Los Angeles, to help us determine whether or not this year’s cool spring means that global warming is a non-phenomenon or a continuing threat, and they tell us that (media hysteria to the contrary) the typical American citizen is safer now than at any time in decades. This is not to say that statistics can’t (or aren’t) manipulated to make a point – but even in these cases we can’t refute (and may not even detect) such manipulation if we lack a sufficient understanding of statistics ourselves. If we refuse to learn a bare minimum of statistics ourselves we are left at the mercy of those who have learned the subject, or we have to go with our gut feelings.

And for that matter, how many decisions do we make based on our gut feelings rather than on a rational examination of the facts? It can be satisfying to make a decision that we know in our bones is the right thing to do, and our popular media is replete with stories of people who buck the odds to do the “right thing.” But these stories stand out because they are so rare – how many times do we hear about a person who took a good look at the information, weighed it carefully, made a decision, and had everything go as expected? Similarly, we hear about the week’s lottery winner, but we never hear about the millions who played the lottery and lost, and never hear about those who chose not to play at all because they understand the odds are against them. Humanity spent millennia developing scientific and rational methods of looking at the world – it’s too bad we are so willing to give this up just as our society has become so dependent on science.

Of course there’s more to decision-making than science – but it seems ludicrous to eschew science altogether. Yet in an increasingly science-avoidant age this is exactly what we’re doing – ignoring statistical evidence when it exists, claiming that our gut informs us better than does our brain, and simply ignoring scientific evidence that contradicts what we want to believe. And what better example of this than the spectacle of a bevy of candidates for the position of President even being asked if they believed in evolution – let alone the fact that all but three claimed they did not? How long will it be until we all think that angels (or demons) are pushing the electrons through our computers to make them work and that magic keeps our planes in the air? How long can we maintain a leading role when there are so many who take perverse pride in their utter lack of scientific understanding? And with so many other threats – acid rain, deforestation, loss of biodiversity, climate change, lack of good drinking water, epidemic and pandemic disease (to name a few) – that can only be resolved through science, this refusal to engage in science becomes even more puzzling and even more dangerous. And – may I point out – that even if you don’t believe that these are problems, you should couch your refutation in science and scientific observation; to do otherwise is to simply choose rhetoric over rationality.

It’s not necessary that everyone in the country understands that our GPS units depend on the theory of relativity to function properly, and it’s not essential that we all realize that the same phenomenon that lights our compact fluorescent bulbs also lights the universe’s distant nebulae. But it is essential that a society that depends on science and technology at least acknowledge this dependence, and that it make an effort to live by the same scientific and rational principles that keep so many of us alive, comfortable, and more prosperous (even in our recession) than at any other time in history. Forgetting the odd fact is understandable and forgivable – turning our backs and willfully forgetting or refusing to learn in the first place is neither.

The post Talk science to me appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The first three installments in this series drew on irrefutable evidence – formerly classified top secret documents and a recording of a presidential phone call – to show that we need to critically question government claims before going to war. Those posts showed that the Gulf of Tonkin incidents, which became the legal basis for the Vietnam War via Congress’ Gulf of Tonkin Resolution, were incorrectly portrayed by the Johnson Administration as unprovoked North Vietnamese aggression. In fact, the second incident never happened and the first incident was, in the words of CIA Director John McCone, a defensive reaction “to our attacks on their off-shore islands.” While the loss of over 58,000 Americans and approximately 2,000,000 Vietnamese is reason enough to avoid future such mistakes, the Vietnam War also added little-known nuclear risks. This post deals with the most bizarre of these, an event that has been dubbed Nixon’s “Madman Nuclear Alert.” A paper by Stanford Prof. Scott Sagan and University of Wisconsin Prof. Jeremi Suri describes the origins and trajectory of this dangerous ploy:

The post Avoiding Needless Wars, Part 4: Nixon’s Madman Nuclear Alert appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Consider a cancer patient whose oncologist is recommending radiation therapy – it would be helpful to be able to sort out the patients who are likely (or unlikely) to suffer complications to healthy tissue. Such knowledge could help doctors better plan treatments and to tailor them according to a patient’s individual genetic profile. This is the sort of work being undertaken by Dr. Barry Rosenstein, a radiation biologist at New York City’s Mount Sinai Medical Center.

What Rosenstein and those in his laboratory look for are single-nucleotide polymorphisms, abbreviated SNP (and pronounced “snip”). The DNA molecule is made of a series of nucleotides (adenine, thymine, guanine, and cytosine – abbreviated A, T, G, and C); these nucleotides are arranged along the chromosome in sets of three (called codons), and the sequence of codons along the chromosome tells the cell how to assemble a protein. My mental image of this process is of a pile of Lego blocks and each DNA codon tells the cell which brick goes where to assemble whatever protein the gene codes for. But what happens when this code gets changed slightly? And that’s what a SNP is – a very limited change to the DNA sequence that can change the function of a single gene.

One possibility is that nothing will happen – if I swap a red brick for a white one in a wall of Legos then whatever I’m building will work pretty much the same, provided the bricks are the same size and shape. Similarly, it’s possible to make some changes to the DNA without really affecting the health of the cell (or the organism) at all. But this sort of change isn’t what most interests Rosenstein – of more interest is what happens when a SNP causes a structural change in a protein; especially when the protein is one that contributes towards a cell’s sensitivity to radiation. This would be the equivalent to, say, replacing a 6-peg Lego block with a 4-peg block – a single such change might not make much of a difference, but accumulate enough of these changes and the structure grows increasingly prone to stress.

Each of our cells has well over 100 genes that help make it more or less sensitive to radiation damage. What Rosenstein and his colleagues were curious about was whether or not it is possible to identify specific SNPs that could help predict which patients might react more strongly to radiation therapy – while every effort is made to spare excessive radiation dose to healthy tissues, sometimes damage happens anyhow. This sort of collateral damage is certainly better than dying of cancer, but it would still be nice to try to minimize it. At this point I should also stress that this is still very much work in progress – I just learned of it last week and I’m looking forward to following the work as it continues.

But let’s consider this a little further – let’s assume that this research pans out and that it’s one day possible to assemble a genetic profile that helps us to better understand each individual’s sensitivity to radiation damage. How could something like this be used?

One obvious application might be in the workplace – what if a nuclear power plant (or an airline or a hospital for that matter) could test prospective employees to see who might be more susceptible to the elevated radiation levels they’d be exposed to on the job. Would it be ethical to give someone a job involving elevated levels of radiation exposure if their SNP inventory showed they were less able to repair DNA damage? After all, how can you justify letting your employees be exposed to a potential hazard that you’ve found out is more dangerous to them than to the average person?

But on the other hand, is this the company’s responsibility or the responsibility of the workers? Let’s face it, workers voluntarily accept risks all the time – think of police and firefighters – shouldn’t it be up to the worker to decide whether or not to accept a risk? This is certainly the approach that has been taken with pregnant women – a company cannot dictate whether or not a pregnant woman can be exposed to potential reproductive hazards; only the woman can make this choice. Similarly, it may be inappropriate for a company to limit a worker’s opportunities based on a genetic test showing a higher sensitivity to radiation – it could be that this decision should only be made by the worker.

On the other hand, companies make decisions about where someone can work all the time and many of these decisions are based on a person’s physiology, much of which can be the result of genetics. A former job required that I have a valid driver’s license – in order to be hired I had to meet all of the physical requirements to legally drive. Not only that, but I also had to be able to lift up to 50 pounds and more and I had to be mentally sound – there are genetic factors that play into all of these. Other jobs also have physical and/or genetic requirements: fighter pilots can’t be colorblind and can’t be too tall to fit into the cockpit, firefighters have to be able to carry equipment and hoses up ladders, and so forth. So if the colorblind are excluded from flying fighter jets, why not exclude the genetically sensitive from working with radiation?

There are court decisions and laws that prohibit discriminating against an individual because of their genetic profile. But isn’t excluding the colorblind from flying fighter jets a form of genetic discrimination? Colorblindness is, after all, a genetic disorder – how can we legally say that a person with this particular genetic ailment can’t fly a high-performance jet?

Part of the explanation is the difference between what might and what will come to pass and how this can affect safety or job performance. Fighter pilots, for example, have to be able to tell the difference between red, green, and white lights in the cockpit. Colorblindness may be genetically determined, but it is something that has already happened and it has a measurable impact on a pilot’s safety and performance. But radiation sensitivity is different – it affects the likelihood that somebody might develop cancer from a given dose of radiation. The risk of developing colorblindness is 100% – in a colorblind person the genes controlling it have been expressed and the affliction has already appeared. And not only that, but it can affect safety. On the other hand, a genetic predisposition to radiation damage is only a predisposition – we cannot say with any degree of certainty that a certain genetic sequence will (or will not) cause a person to develop cancer. So we can discriminate against the certainty of a physical trait that affects one’s ability to do our jobs safely and effectively, even when that trait is genetically determined. But we cannot discriminate against a person who simply has a higher possibility of having an adverse effect.

Putting this all together, the possibility of using genetic analysis to help make more informed medical decisions is both promising and exciting. But let’s hope that, as these techniques become better refined and more prevalent, they are not used inappropriately or discriminatorily.

The post SNPs and radiation sensitivity appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The post Avoiding Needless Wars, Part 3: Are We About to Repeat the Mistakes of Vietnam? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The government has taken a stab at answering this question in the past and has recently done so again. And every time the recommendation comes down in favor of leaving a little bit of contamination behind the government catches a lot of flack – most recently last week.

I alluded to this problem in a recent post in which I discussed the matter from the standpoint of a concerned father. No matter how much the scientist in me might be convinced that residual contamination levels pose no risk to my kids, the father in me is going to have concerns. The question is not whether or not I can suppress these concerns but, rather, whether or not I can reconcile the opinions of both scientist and father.

Part of the problem is that most people have a visceral reaction to radiation and radioactive contamination. And when someone has an emotional reaction it’s hard to convince them with scientific evidence and reasoning. Even more difficult when they have an emotional stake (a child perhaps) in the fight.

The science behind the suggested governmental standards is fairly straight-forward – radiation can be harmful, but low levels of radiation exposure aren’t nearly as harmful as many people think. Not only that, but there are loads of people who live in natural high-background radiation areas who see to tolerate the radiation without any apparent harm. So leaving some contamination on the ground might seem sloppy, but up to a point it doesn’t pose much of a risk – certainly less than the risk from driving.

So maybe there’s not a strong health and safety argument for cleaning up to background levels, but there’s still the aesthetics to consider – even if the health risk is minimal, shouldn’t we try our utmost to restore a site to its original, pre-contaminated condition?

Nice in theory, but the practice makes things more difficult. Characterizing background radiation levels can be difficult, and we have to remember that instruments give results that vary slightly from reading to reading. Say I measure background radiation levels at 10 microR/hr (don’t worry about the units for the moment – just the magnitude of the reading) and that a dirty bomb goes off and raises background radiation levels to 1500 microR/hr. Where do we stop our cleanup? If I get a reading of 15 microR/hr does this mean that there’s still traces of contamination remaining or am I looking at a statistical fluctuation in background radiation readings? Or maybe I’m using a different meter than previously – maybe all of the contamination has been cleanup up, but the new meter just reads higher. All of these are plausible – but which one is the actual case (and how can I find out)? And on top of that, does it really matter?

The fact is that it’s not easy to know when we’ve reached background, so it’s not uncommon for cleanup to proceed to a certain level above background. This is the case for universities, for nuclear power plants, and even for cleanups overseen by the Environmental Protection Agency (EPA). So if the typical standard is that it’s OK to leave a little bit of contamination behind for environmental restorations or for the release of facilities and equipment for unrestricted use, why should it be any different in the aftermath of an RDD attack? And further – it might make sense to make a radioactive materials licensee remove as much contamination as possible, but what should be the standard in the aftermath of a terrorist attack? Can we cut ourselves a little bit of slack? This is the question that the recent government guidelines were attempting to answer.

The Obama administration has been taking unnecessary criticism over this set of recommendations. Those who oppose these relaxed limits are overlooking the fact that society will have a ton of concerns after a dirty bomb attack and radioactive contamination is only a small part. Consider – setting lower cleanup levels means cleaning up a larger area which costs more money. It also means that the cleanup will take longer – putting displaced residents and businesses in hotel rooms or temporary quarters for a longer period of time. Not only that, but consider the cost of cordoning off valuable parts of a city for longer periods of time, and the cost to a city from the loss of tourism, tax revenues, and jobs. The longer a chunk of territory is out of commission the greater the cost – monetary, social, and sociological – to the city and its residents. Does it make sense to double cleanup time and to quadruple cleanup costs – not to mention the other economic factors mentioned above – when a city is trying to get back on its feet?

One other factor to throw into the mix is the cost to a displaced population – not the monetary cost so much as the social and health costs. A 2006 study by the World Health Organization found that the greatest health costs to those displaced by the Chernobyl accident was the mental health cost – anxiety, substance abuse, suicide, and so forth, all of which skyrocketed in the aftermath of the accident, and all of which remain elevated even today. The mental health toll from Chernobyl –particularly among those who were forcibly evacuated – is at least as great as the health toll from radiation exposure. If we look only at the health risks from radiation exposure to the exclusion of everything else – economic, sociological, mental health, and so forth – we are making decisions based on incomplete information. We simply have to accept that fact that radiation might be a significant concern, but it is not the only concern in such situations.

In my opinion, many critics are taking cheap (and scientifically indefensible) shots at the administration. The administration doesn’t have the luxury of focusing on only one aspect of this problem – they have to consider all of the ramifications of their policy. Those who focus on radiological issues to the exclusion of everything else are simply missing the big picture –either through ignorance or willfully – and in so doing, they are doing society a disservice.

The post How clean is clean? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Page 3 of that history, with the above excerpt highlighted, is reproduced below and is worth reading in its entirety, as is the complete NSA history.

Adm. James Stockdale, who was overhead in a jet fighter sent to provide air cover for the Maddox and Turner Joy corroborates that this second attack never occurred:

Adm. Stockdale goes on to describe how the American media added to the war fever by portraying the non-existent incident as a spine-tingling sea battle:

Incorrect US government claims of unprovoked North Vietnamese aggression in the Gulf of Tonkin created a drum beat to war which led to the deaths of over 58,000 Americans and approximately 2,000,000 Vietnamese. Yet the unimpeachable sources cited in these first two posts prove that those claims were at best mischaracterizations, and at worst outright lies. A future installment in this series will highlight how our involvement in Vietnam heightened the risk of a nuclear war. Thus, avoiding needless wars not only saves blood, treasure, and national honor. It also reduces nuclear risk. Other installments will highlight other wars or near wars that were based on governmental misinformation. In light of that history isn’t it time we started asking more questions before joining the march to war? That question is of direct current relevance because Senate Resolution 65 – a kind of “Iran War Gulf of Tonkin Resolution” – is currently under review. That resolution will be covered in more detail in the next post in this series. Stay tuned!

Martin Hellman

Reference and Note Adm. Stockdale’s quotes are from: Jim and Sybil Stockdale, In Love and War, Harper and Row, New York, 1984, pages 19-20, 24-25, 33-36. It should be noted that Adm. Stockdale, rather than thinking that Vietnam was a needless war, saw it as inevitable and necessary to stop communist aggression. His concern was that we had gone to war under false pretenses which, if discovered, would aid the anti-war movement and the North Vietnamese propaganda effort. After he was shot down in September 1965, his greatest fear during his long captivity was that the North Vietnamese would recognize that he had been flying air cover on the second, non-existent Gulf of Tonkin incident, would torture the truth out of him, and use it to hurt the American war effort. Throughout the book, he and his wife argue that the solution was to unleash America’s air power without reservation, even if it risked bringing Russia and/or China into the war – as happened with China during the Korean War. So we’re already seeing some of the connection between wars like in Vietnam and nuclear risk.

The post Avoiding Needless Wars, Part 2: The Second Gulf of Tonkin Incident appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

My guess is that virtually everyone reading this, no matter how where you stand on the biological effects of radiation exposure and no matter how cavalier you might be with your own radiation exposure, you’d hesitate to accept extra exposure to your kids. And it’s probably not a rational response; any more than any of our other concerns for our kids. I know I feel that way – if you’ve been reading this blog for any length of time you’ve most likely noticed that I am not overly concerned about low doses of radiation. At the same time, I have to admit that I’d have trouble telling my own daughter to snuggle up with her favorite (albeit lightly contaminated) Pooh bear.

This discrepancy is because there can be a disconnect between the head and the heart. I am utterly convinced that detectable contamination – say at the limit of 1000 decays per minute – would pose no threat to anyone; this is why it’s acceptable to release items with this level of contamination for unrestricted use. It would be good enough for me – but not for my girl.

So let’s think about the aftermath of a radiological emergency; one that’s spread contamination across a city, inside schools and businesses, and through homes and apartments. Cleanup will cost a fortune – maybe tens or hundreds of billions of dollars – and the more stringent the cleanup standards the more it’s going to cost. As a health physicist and a scientist I can crank out numbers to tell our elected and appointed officials how much radiation dose people will received from any level of contamination – and if they don’t believe me then I can run the numbers on a computer program such as RESRAD (for RESidual RADioactivity). But convincing an elected official – not to mention the workers, residents, and parents – to let people reoccupy an area that hasn’t been cleaned up to pre-emergency levels is going to be a hard sell.

So let’s think about the cost of every incremental bit of cleanup. Say that (in a hypothetical situation) contamination is evenly distributed and that contamination levels drop off proportionally with distance – doubling your distance from the center halves the contamination levels, tripling your distance reduces contamination by a factor of three, and so forth. Since the area of a circle is proportional to its radius this means that reducing contamination levels by a factor of two will increase the area to be cleaned up by a factor of four. So if the level of risk is directly proportional to the contamination levels, and if the cost of cleanup is proportional to the area cleaned up (both a bit on the simplistic side, but probably not too far off) then we can conclude that cutting your risk in half requires spending four times as much for remediation, and it’ll cost nine times as much to cut your risk by a factor of three. It’s not hard to see that costs skyrocket as we try to clean up to ever-lower levels – at what point do we stop cleaning up and decide to simply live with a little bit more contamination?

Ask a radio-phobe and the answer is obvious – clean up until all contamination is gone. A regulator would likely tell you to clean up until you meet the appropriate regulatory limits, and a scientist might answer that cleanup should proceed until the marginal reduction in risk is balanced by the increased cost. Which way will the decision go in an actual emergency? I honestly don’t know, and I don’t envy those who have to make such a decision.

The post A contaminated teddy bear appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Wednesday marks the tenth anniversary of the Iraq War, a very appropriate time to reexamine ways that we have been fooled – or even worse, fooled ourselves – and gotten into needless wars. Avoiding such debacles is key to Defusing the Nuclear Threat because every war has at least a small chance of escalating to the use of nuclear weapons. The Vietnam War serves as Exhibit A in this argument since Nixon’s “Madman Nuclear Alert,” detailed in a later installment in this series, added needless nuclear risk and was motivated by his desire to end the war on terms favorable to him.

This first post in the series treats the first Gulf of Tonkin incident, which played a key role in President Johnson’s justification for the war. It occurred on August 2, 1962, when North Vietnamese PT boats attacked the USS Maddox in the Gulf of Tonkin. Two days later the second Gulf of Tonkin incident (to be treated in the next installment in this series) occurred when the Maddox and the Turner Joy, which had been sent to reinforce it, reported that they were attacked yet again. These seemingly rash, aggressive North Vietnamese actions became the basis for Congress’ Gulf of Tonkin Resolution which gave President Johnson a free hand to escalate the war. Before it ended, that war killed over 58,000 Americans, and approximately 2,000,000 Vietnamese.

President Johnson, Secretary of Defense Robert McNamara, and many others created a war fever by characterizing North Vietnam’s attacks on the Maddox – and the later attack on the Maddox and the Turner Joy – as “unprovoked aggression.” But formerly classified information shows that the North Vietnamese were responding to earlier, covert American attacks on North Vietnam. On August 3, the day between the two incidents, LBJ told former Treasury Secretary Robert Anderson in a phone call which he secretly taped:

OK. Here’s what we did. We [were] within their 12-mile limit, and that’s a matter that hasn’t been settled. But there have been some covert operations in that area that we have been carrying on –  blowing up some bridges and things of that kind, roads, and so forth. So I imagine they wanted to put a stop to it. So they come out there and fire and we respond immediately with five-inch guns from the destroyer and with planes overhead. And we cripple them up – knock one of them out and cripple the other two. And then we go right back where we were with that destroyer [the Maddox], and with another one [the Turner Joy], and plus plenty of planes standing by. And that’s where we are now. [emphasis added]

You can hear that part of the conversation in the one-minute audio clip below by pressing the play button.

[audio http://nuclearrisk.org/1964_0803_johnson.mp3]

As further evidence that the first Gulf of Tonkin incident was not unprovoked aggression, a formerly top secret NSA history of the Gulf of Tonkin incidents notes:

At 1500G [3 PM Gulf of Tonkin time, 3 AM DC time, on 2 AUG], Captain Herrick [the task force commander, who was on the Maddox] ordered gun crews to open fire if the [PT] boats approached within ten thousand yards. At about 1505G, the Maddox fired three rounds to warn off the communist boats. This initial action was never reported by the Johnson administration, which insisted that the Vietnamese boats fired first. [emphasis added]

In summary, the war fever created by North Vietnam’s seemingly rash and unprovoked aggression was based at best on mischaracterizations, and at worst on outright lies.

Continuing the series of errors, the next installment in this series will use other formerly top secret documents to show that the second Gulf of Tonkin incident never happened.

Martin Hellman

This is the first in a series of posts on Avoiding Needless Wars, and is the only one I cross posted to the FAS web site. If you want to see the others, you can find them on the Defusing the Nuclear Threat blog.

The post Avoiding Needless Wars, Part 1: The First Gulf of Tonkin Incident appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Let’s take one example – there was general agreement that it could be acceptable to hold a person (or a group of people) for decontamination if they were to pose a substantial risk to public health. But who makes this determination and what do they base it on?

Consider the possibility of a health physicist being asked to give testimony to a judge in favor of detaining a person (or people) covered with radioactive contamination. One way to approach this would be to point out that, according to the Linear No Threshold hypothesis of radiation dose-response, every added bit of radiation exposure adds risk. Thus, letting a contaminated person walk the streets adds to the risk of every person encountered, even if only a little bit. But given that there is incremental risk, why not err on the side of caution and simply hold all of those who are contaminated until they’re cleaned off? After all, who could object to a shower and a change of clothes? On the other hand, who has the right to force someone to disrobe (and throw away their clothing) and shower before heading home? The bottom line is that we have to balance the risk to society versus individual rights – in a society that already accepts the risks of driving, eating fast food, and so forth.

On the other hand, I can also argue that the Nuclear Regulatory Commission has already answered this question, although somewhat indirectly. Consider nuclear medicine patients who, after being injected with radioactivity, are often sent home. The NRC seems to have decided that nuclear medicine patients do not pose a substantial risk to public health – if so, then how can we justify detaining someone who has less radioactivity on their clothing and skin than a nuclear medicine patient carries within their body?

The problem is the fuzziness of the operative words. Take risk for example – I’m sitting in a chair right now typing away and I’m at risk. The people in the apartment above mine could fall through the floor, a truck could careen into my apartment, we could have a fire in my building – any of a number of things could happen to me as I sit here typing away and all of them are pretty unlikely. So I’m at risk – the question is how substantial that risk is. In my case the risk of sitting in front of a computer is pretty low – maybe a single chance in many millions that ill will befall me. So do we need to take protective measures to protect me against the chance that a truck might drive into my living room? Actually, we have to some extent. Building codes help to protect me against the risk of structural collapse and traffic laws help to protect me from stray trucks – not perfectly, of course, because buildings still collapse and trucks still run off-course. But the residual risks are low enough that I’m not too concerned. So yes – I am at risk from any number of things, but those risks are not substantial enough for me (or most people) to worry about. Similarly, the NRC has decided that the risk posed by nuclear medicine patients is not substantial enough to worry about.

I guess that brings up the question of what constitutes a substantial risk. Probably most of us would agree that a 10% risk of death would be far too high, and even a 1% risk would also be a bit on the high side for most of us (even though that’s about the risk we face from driving). Similarly, I’m guessing that most of us would agree that it doesn’t make much sense to spend money to mitigate a risk of one in a billion. And many would even consider one chance in a million to be too skimpy to warrant a huge investment to prevent. So somewhere between one chance in a million and one chance in a thousand is where society starts to consider a risk to be “substantial” enough to warrant taking preventative measures.

So – do we confine people who are contaminated after a radiological accident or not? Do they pose a substantial threat to public health?

From my perspective as a scientist it’s hard to give a unique and unambiguous answer to this question because what I consider to be “substantial” might horrify some and leave others blasé. But give me a solid target to aim at – a number that can be calculated or measured – and I’m on much firmer ground. For example, the NRC guidance on nuclear medicine patients is based on keeping radiation dose to members of the public lower than 100 mrem – give me a number like that and I can tell you what level of contamination will produce that dose; anything lower than that level would be acceptable and anyone with higher levels of contamination would need to be held for decon. But lacking a number – giving me fuzzy words like “substantial” and “danger” – takes away my tools as a scientist and makes it harder to answer objectively.

So let’s recap a little bit. The fundamental question is whether or not the government can (or should) detain contaminated people after a radiological event. But before we can make that decision we have to decide when it’s acceptable to deprive someone – even briefly – of their liberty. This would seem acceptable only if the risk to society (in this case, public health) is high enough to warrant the detention. But since so many people have different subjective views of what constitutes a “substantial risk” it might be better to develop a numerical standard – such as the NRC’s standard for releasing nuclear medicine patients.

So – to wrap this up, I should also note that there are no existing standards to help address this problem. So the first step might be to ask an advisory body to develop a numerical recommendation: In the aftermath of a radiological emergency, at what point – at what dose to the public – do we restrict people for the overall good of society? Once we have a recommended standard to hang our hat on the rest could fairly easily fall into place.

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Every so often we hear something in the news about nuclear reactors fueled with highly enriched uranium (HEU); usually with regards to nuclear weapons proliferation. Back in the good old days both the US and USSR constructed over a hundred small HEU-fueled reactors and shipped them all over the world – Uruguay had one, there were some in the Balkans, the Ohio State University reactor was fueled with weapons-grade uranium, and there were plenty more. Given today’s concerns about locking up and accounting for every gram of weapons-grade uranium it’s only natural to wonder “What were they thinking?”

Even today there are a number of reactors fueled with uranium that could be turned into nuclear weapons. One category is military reactors – the nuclear reactor on my submarine was fueled with HEU. But outside of the military, the biggest reason to use high enrichments is for research and to produce radioactive materials for research and medicine. Here’s why.

First a little bit of background. Two kinds of radionuclides are produced in nuclear reactors – in one, stable atoms that capture a neutron can become radioactive by a process called neutron activation and the products are called neutron activation products (activation products for short). Cobalt-60 is a neutron activation product, formed when stable cobalt-59 captures a neutron to become radioactive cobalt-60. In the other process, a uranium atoms splits (fissions) and the fission products are radioactive; these include the nuclides we saw in Fukushima (radioactive isotopes of iodine and cesium mainly) as well as molydebenum-99 (the parent nuclide of technetium-99 that is the workhorse of nuclear medicine) and others.

So – to create a neutron activation product you need two things – target atoms (such as cobalt-59) and neutrons; the neutrons come from uranium fission. All things being equal, a larger number of neutrons means a larger amount of radioactive product; a higher flux of neutrons means more rapid production. The way to get a lot of neutrons is to have a lot of fissions – the more fissionable atoms that are crammed into a volume, the more neutrons. A higher uranium enrichment is the best way to cram the highest number of fissionable atoms into a volume and, thus, to increase the neutron flux.

With fission products this rule works double – a larger number of fissionable atoms not only boosts the neutron flux but it also gives a larger number of target atoms to fission. So, again, using more highly enriched uranium produces a higher yield of the desired nuclides. And with nuclides that have a low probability of being produced the only way to make useful quantities is to use more-enriched uranium.

In both cases we end up with the same choice – do we choose the greater profits from HEU or the lower risks of LEU? An LEU-fueled reactor can do everything that an HEU-fueled one can – just more slowly.

At the moment it looks as though the nation is moving towards security rather than production. Unfortunately for the nuclear medicine industry this coincides with the shutdown of some Canadian reactors that produced medical isotopes, causing some shortages in our supplies of medical nuclides.

With medical science using radionuclides in ever-increasing amounts, this places a strain on our nuclear medicine system (with the exception of PET nuclides, which are produced on-site in a type of particle accelerator called a cyclotron). Our only real options are to cut back on nuclear medicine procedures or to build more isotope production reactors.

There is more to HEU-fueled reactors than producing medical nuclides – they’re also used to produce nuclides for industry, for basic research (bombarding rocks with neutrons, for example, can tell us what the rocks are made of), developing and testing nuclear instruments, and more. All of these things go more quickly with a higher neutron flux, but they can also be done in a less neutron-rich environment. When we put it all together we pretty much have to conclude that HEU-fueled reactors are nice, but they’re not essential. If our priority is to make the largest amounts of nuclides possible then we need the HEU-fueled reactors; if security is more important then we have to shut them all down and replace them with the slower (but more proliferation-resistant) LEU-fueled devices.

There is one development that might help to resolve this issue to some degree – using high-density LEU fuel. In this case, the uranium is kept at 20% enrichment (which is unsuitable for making a bomb), but it’s packed into the fuel more tightly than in a standard reactor. The higher density of U-235 atoms can produce both a higher neutron flux and the dense packing of fission products (more or less) that will help to produce both activation and fission products. Although this type of fuel has been under development for over 30 years it never really caught on. It could be that it’s time has finally arrived.

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radiation-damaged chromosomes

Radiation is ubiquitous; an inescapable part of life on Earth.  Background radiation reaches us from outer space, from the rocks and soils we walk on, and from naturally radioactive potassium in our own bodies.  Through its entire history, organisms on Earth have been bombarded by radiation, and this will continue for as long as the Earth exists.  Today, the average person in the US is exposed to about 300 mrem each year from natural background radiation – about 1 mrem a day – and this level of radiation exposure seems to have no ill effects.  Of the estimated 600 or so mutations that occur in each of our cells each year (about 900 in those cells exposed to UV radiation), only about 5 are due to the effects of background radiation.  In short, environmental radiation is a mutagen, but it is not a major source of DNA damage. 

At higher levels, however, radiation can cause damage.  Continual exposure to low levels of radiation may cause a mutation that can initiate cancer.  Brief exposure to high levels of radiation can cause skin burns, radiation sickness, or a number of radiation-induced syndromes.

Radiation Damage to Cells

Radiation can damage cells by directly striking the DNA and causing damage such as single- or double-strand breaks or point mutations.  It’s more likely, however, that the radiation will interact with molecules in the cell’s cytoplasm, splitting them apart and forming reactive molecules called free radicals.  These free radicals, then, go on to cause DNA damage.  Free radicals are caused by more than just radiation – our mitochondria leak free radicals all the time, metabolizing our food can create free radicals, and even dissolved oxygen in our cells can cause DNA damage.  All of this damage is indistinguishable, with the exception of double-strand DNA breaks – we can’t “look” at a point mutation and tell if it was caused by radiation or mitochondrial free radicals.

When radiation passes through a cell the effects can range from non-existent to profound.  There’s a chance, for example, that a gamma ray will pass right through a cell without interacting at all or that the free radicals produced will simply recombine or be scavenged before they can reach the DNA.  If radiation (or the free radicals it produces) do interact with the DNA, there are only a few possibilities – either the DNA will be damaged or it won’t.

If the DNA is damaged, we have a few further possibilities – the damage may be beneficial (e.g., evolutionary advantage), harmful, or neutral (neutral damage is damage that has no effect on the cell – it may be in non-coding part of the DNA, or to a gene that’s not expressed in that particular cell, for example). If the damage kills the cell there’s no problem – in reality, the only way to cause problems is to have DNA damage that’s not fatal to the cell and that affects one of the handful of genes that can cause a cell to become cancerous.

However, the possibilities do not stop here, because our cells have DNA damage repair mechanisms – think of them as being like a spell checker; as long as they repair the damage properly then it’s as though it never occurred.  Although these mechanisms are very effective, they are not perfect.  This means that any bit of DNA damage may be repaired properly, may be repaired improperly, or might not be repaired at all.  It is at this point that DNA damage may become a mutation – a mutation is what happens when damage to our DNA becomes “fixed” and is able to be passed on to the next generation of cells.  As with DNA damage, mutations may be good, bad, or indifferent (neutral), and the detrimental mutations may be lethal or sublethal.  And, as before, it is only the sublethal damage that’s of interest to us, and then, only if it can cause the cell to become cancerous.

I’ve taken several paragraphs to describe the different possibilities of radiation interacting in a cell.  Part of this is for the sake of completeness, but it’s also to help drive home an important point – radiation is a weak carcinogen.  If we sum up all the possibilities above, I count over 20 different possibilities.  Of these, only 1 (sublethal damage that is misrepaired or unrepaired and causes a cell to become carcinogenic) have a chance of causing cancer.  Radiation is a carcinogen, but it’s not a very good one – not compared to many of the chemicals we work with.

In the next few sections, I will talk a little more about the effects of both acute and chronic radiation exposure on the organism, instead of the individual cells.

Acute exposure

If we are exposed to high levels of radiation in a short period of time, we will suffer from the effects of acute radiation exposure because the damage accumulates faster than it can be repaired.  If the dose is to a limited part of our bodies, we may end up with skin burns, sometimes severe.  There have been many instances requiring amputation of fingers, or even entire limbs.  High levels of radiation exposure to the whole body can lead to radiation sickness or death.

The effects of high radiation dose to limited parts of the body may range from no observable effects (if the dose is low enough) to blistering, burns, or necrosis depending on the dose received.  The effects of whole-body acute radiation exposure can be a bit more complex, and they are summarized in the following table.

Chronic exposure

The primary concerns with chronic exposure to relatively low levels of radiation are that we will develop cancer.  There are two competing hypotheses on this matter, and the matter is still far from being settled.

LNT

The linear, no-threshold (LNT) hypothesis suggests that all radiation exposure is potentially harmful (the “no-threshold” part), and that the risk of getting cancer from radiation is directly proportional to the dose received (the “linear” part).  LNT is the most conservative radiation dose-response model in that it predicts the highest risk from a given amount of radiation exposure.  This is one of the reasons that the LNT is the foundation of radiation regulations virtually everywhere in the world – since we really aren’t sure how we respond to low levels of radiation exposure, it makes sense to control dose (and risk) according to the most conservative model.

One problem with the LNT is that it can be used to predict cancer risks down to vanishingly small levels of exposure, and so it has been used to calculate expected cancer rates from exposure to radon, “dirty bombs,” and medical x-rays.  For example, say that the risk of getting cancer from a given radiation exposure is 5 additional cancer deaths for every 10,000 person-rem.  That means that exposing 10,000 people to 1 rem each should result in an extra 5 cancer deaths among those people.  Or, exposing 1 million people to 10 mrem each should also lead to 5 added cancer deaths.  It’s easy to see that we can use this model to predict added cancer deaths from any level of radiation exposure, no matter how trivial, if enough people are exposed.  By analogy, we can also say that, since a 1000 kg rock will crush someone, throwing a million one-gram rocks at a million different people will crush someone.

This doesn’t make much sense, and both the Health Physics Society and the International Commission for Radiation Protection have advised against this misuse of the LNT model.  In fact, we just don’t know what happens at such low levels of exposure, and we can’t make any such predictions for very small levels of exposure.  According to the Health Physics Society, in two separate position papers (which can be found on the HPS web page at www.hps.org), we simply can’t calculate a numerical risk estimate from any exposure of less than 10 rem, so even the first calculation runs afoul of HPS recommendations.  In a similar vein, the ICRP has suggested that, when looking at the risk from collective dose, if the most highly exposed individual receives a trivial dose, then everyone’s dose should be treated as trivial.

Threshold/Hormesis models

Virtually all harmful substances exhibit some level below which there are no apparent harmful effects.  This is part of the idea behind the No Observable Adverse Effects Level (NOAEL) – below a threshold dose you simply don’t see any effects from exposure to a substance.  There are those who feel that radiation probably behaves similarly – that there is a level of exposure below which there are observable effects from radiation exposure.

There are also those who think that exposure to low levels of radiation may be beneficial.  This is called hormesis and, although it sounds implausible at first blush, there are plenty of examples of hormesis in the world.  Two examples are vitamin D and selenium.  Both of these substances are vital nutrients, and both are acutely toxic in sufficiently high doses.  Low doses of aspirin can help to stave off heart disease (not to mention the beneficial effects on fever, pain, and inflammation), yet high doses of aspirin can be fatal, and people can also die of excessive salt intake or even water intoxication.  In short, the idea of hormesis is not outlandish; only the application of hormesis to radiation exposure seems unusual because we are all so steeped in the idea that radiation is uniformly bad.

The idea behind assuming a threshold in our response to radiation exposure is that, given the variations in Earth’s background radiation field, it makes sense that our cells should be able to adequately repair DNA damage from slightly elevated levels of radiation.  And, let’s face it; radiation is not one of the major environmental mutagens (it accounts for about 1%-5% of background DNA damage).  Our biochemistry contains very effective mechanisms for repairing DNA damage, and it is thought that these mechanisms are able to accommodate some level of added damage, such as would result from exposure to low levels of radiation.

The thinking behind positing hormesis effects is that, by presenting a continuing challenge to our mutation repair and tumor suppression mechanisms, they are kept at peak operating efficiency.  They are better able to contend with the ordinary, garden-variety damage that is always cropping up in our genome and, as such, our DNA is better protected than if this radiation exposure was removed.

The best way to test these hypotheses, of course, is to perform epidemiological studies of exposed populations, and many such studies have been performed with equivocal results.  Researchers have looked at radiation workers, residents of natural high-background areas, radon concentrations versus lung cancer rates, radiologists, and atomic bomb survivors, among others.  Some studies show that risks are slightly higher, some show no effects at all, and some show fewer cancers than expected in the study populations.  Part of the problem is that the effects are often smaller than the error bars, and this makes it very difficult to pick out what is actually happening.  Unfortunately, there is not yet a “gold-plated” study that everyone can point to and agree that it was properly done, controlled for all confounding factors, and shows a significant result.

Given this degree of uncertainty, many health physicists and most governments feel it is best to control radiation exposure under the risks of the highest-risk model, LNT.  The thinking is that, if we maintain risks at a low and acceptable level under LNT, then whichever model is correct, we will be at no more risk than we have agreed we can accept.  The only problem with this model is that, if one of the other models better represents reality, we will have spent a lot of time, effort, and money controlling illusory risks, and these resources will have been taken away from more effective risk-reduction measures.  So this question needs to be answered, and we will hopefully be able to do so before too much longer.

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According to an NBC News report: “Two Russian bombers, capable of carrying nuclear cruise missiles, circled the U.S. island of Guam in the Western Pacific this week, U.S. military officials told NBC News. U.S. Air Force F-15 jets scrambled from Andersen Air Force Base on Guam to intercept the bombers.” While those same U.S. military officials played down the seriousness of the incident, Stanford’s Dr. Pavel Podvig explained how a similar Russian military exercise scheduled for September 11, 2001, entailed far greater risk than anyone might have imagined:

One of the [American] fighter pilots who was scrambled into the air on September 11, 2001 [after the Pentagon was hit by one of the hijacked airliners] was reported to testify that: “I reverted to the Russian threat – I’m thinking cruise missile threat from the sea. You know, you look down and see the Pentagon burning and I thought the bastards snuck one by us.”

If on September 10, 2001 someone would suggest that a U.S. pilot would assume that Russia might attack the United States, that person would have been laughed out of the room. But this is exactly what happened. Two more “coincidences” of that day – NORAD was scheduled to conduct an exercise, known as Vigilant Guardian, “which postulated a bomber attack from the former Soviet Union,” while Russian strategic bombers were indeed conducting an exercise that involved flights in the direction of the United States. As far as we know, NORAD never began the exercise that day and the Russian military grounded the bombers as soon as they learned about the events in the United States, but the number of coincidences is quite alarming.

Not that there are any signs that the military on both sides have changed their plans and no longer practice attacking each other. Just recently Russia conducted a large-scale exercise of its strategic bombers, in which they got close enough to the United States to be intercepted by NORAD fighter planes. The United States also routinely conduct exercises that involve a nuclear exchange with Russia.

The Cold War should be over, so isn’t it time we worked with the Russians to end such dangerous practices?

Martin Hellman

Reference 1 For the American pilot’s testimony, see the 9-11 Commission Report, page 61, or Kindle Location 1290.

Reference 2 For Vigilant Guardian, see the 9-11 Commission Report, page 565, or Kindle Location 9480.

Reference 3 For the Russian Air Force grounding its bombers, see “Ядерный конфликт отставить,” 12 SEP 2001. The English translation of the relevant part states:

As Air Force Headquarters had announced, immediate corrections had been made to the currently ongoing training of the Russian strategic bombers.  According to Russian Air Force spokesman Colonel Drobushevsky, “practical measures as part of the maneuvers have been canceled”; meaning that Russian strategic bombers will stop flying towards the United States, Canada, Norway, Great Britain, and Iceland.

This entry is repeated from my blog “Defusing the Nuclear Threat:” http://nuclearrisk.wordpress.com/2013/02/16/risky-business/.

To learn more about the level of nuclear risk, visit my related web site.

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First, let’s think about why another North Korean nuclear weapons test was almost inevitable – and let’s leave speculation about the youngest Kim’s personal and political reasons aside. North Korea had two earlier tests, both of them very low-yield. In fact, their first test was so low-yield that there was a bit of speculation about whether or not North Korea might have just faked it by filling a cave with conventional explosives and setting those off. Air sampling around the periphery of North Korea showed the presence of fission products which pretty much confirmed that there had been fission taking place, but so small a yield seemed likely to have been the result of a mistake in the weapon’s design or construction – from that it was virtually inevitable that there would be a second test, if only to prove to themselves and to the world that North Korea was capable of building a full-on nuclear device. That was more or less shown by their second test – significantly more powerful than the first, although still only a small fraction of the yield of the Hiroshima and Nagasaki devices.

So – North Korea showed the world in their second test that they could design and build a nuclear device – why in the world would they risk more condemnation and sanctions by testing a third one? There are good reasons for nuclear weapons testing - here are a few that might apply in this case.

Part of the answer might well be that they just don’t care what the world thinks about them. All three Kims seem to have made a point of using international condemnation as a point of pride and as a way to help strengthen their government. And part of the reason might well be that the perceived benefit derived from showing the world a working North Korean nuclear weapon outweighs the perceived cost of yet another round of international hand-wringing and punishment – just as tacking a few more years on a life sentence might not deter a prisoner from attacking someone who’s threatening him.

Another part of the answer might be that North Korea needed to show that their nuclear weapon is an actual threat. A “fizzle” might destroy a city block or two, but it doesn’t inspire as much fear as a full-blown nuclear device. But now that North Korea has shown the world that it can field a weapon of the same class as the Hiroshima and Nagasaki devices its enemies (real or perceived) have to acknowledge that the threat level has ratcheted up a notch.

Not only that, but North Korea claims that the device it tested was smaller and lighter than their other two devices. If we assume that this is true then the recent North Korean rocket launch raises the possibility that there could be a nuclear-tipped missile coming out of Pyong Yang in the near future. While North Korea has to realize that a nuclear attack on any American city would almost certainly lead to our raining down nuclear annihilation upon them – every missile launch comes with an easily verifiable “return address” – they might feel that an attack against Japan or South Korea might not produce the same response.

One of the questions that only air sampling will answer (hopefully) is whether this device is based on plutonium as previous North Korean weapons were or if North Korea has got their uranium enrichment program to the point of building a uranium weapon (the fission products created by U-235 fission are subtly different than those produced by the fission of Pu-239). If it’s a uranium device then this not only means that North Korea has diversified their nuclear weapons program, but that they’ve got a working system to enrich uranium  to weapons-grade; something they had not previously demonstrated.

Of course there are other concerns than North Korea’s having a nuclear weapon. One is that the North Koreans have been implicated in working with both Myanmar and Iran to develop nuclear weapons – a successful demonstration of a higher-yield device would certainly show their potential clients that North Korea has effective technology for sale. Not only that, but North Korea has a history of selling pretty much any of their military technology to anyone with a checkbook – we have to consider the possibility that this test might also be a sort of advertisement to potential buyers. The point is that North Korea is already being punished by terrible sanctions and they’ve been on the international list of bad performers for many years – it seems safe to think that the potential benefits to North Korea are high enough to make this test (and potential future tests) worthwhile.

And this brings up another thought – that North Korea might be tempted to sell a working nuclear weapon to a nation or a terrorist group that might be tempted to use it against us or one of our allies. One way to try to forestall this might be to make it very clear to North Korea that if one of their weapons is used against us or one of our allies – whether by them or by one of their customers – would be viewed as an attack by the Koreans. The only way to pull this off, of course, would be to gather some high-quality data from this (and their previous) tests so that our nuclear forensics experts could unequivocally identify the weapon as a North Korean design and manufacture. But North Korea should have absolutely no doubt that we consider them responsible for the manner in which all of their weapons are used – whether those weapons were detonated by them or by one of their “customers.”

So, to recap, here are the questions and some possible answers:

• What was the actual yield of North Korea’s new device? (A careful analysis of seismic data should tell us)
• Was it a new uranium device or a plutonium bomb? (Nuclear forensics – if we can catch enough fission product atoms – will give us this information)
• Was the device an advanced miniaturized design as North Korea claims? (We might not know unless we can get some inside information)
• Can North Korea’s newest weapon be carried by one of their ballistic missiles? (Again, no way to know at the moment – but they must know that launching against us or our allies will be fatal to their nation)
• Will North Korea put nuclear weapons up for sale? (Possibly – but if we can get good enough forensic information to positively ID North Korean uranium or plutonium we might be able to dissuade them)

The bottom line is that there’s no doubt that North Korea’s latest test tells us and the rest of the world that they are, without a doubt, a genuine nuclear power. Given the nature of the regime, this makes the world a bit more dangerous place than it was last week. But that’s life. It’s too late to prevent North Korea from developing nuclear weapons, but hopefully we can persuade them that this particular line of proliferation must stop with them.

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We see this approach all over the place in the form of cost-benefit analyses. But these analyses are typically used for business decisions or for decisions with monetary implications – far less often do we total up lives lost and saved to determine what actions we should take.

What would you do, for example, to stop a war in which millions might die? Would you let the government execute a condemned murderer if his death would prevent a war? Or to put a finer point on the matter, would it be acceptable to execute someone like Charles Manson (currently serving a life sentence for multiple murders committed in 1969) in order to save millions of lives?

A strictly utilitarian answer would be “of course” since millions of lives saved far outweigh one to be taken prematurely – and a not very attractive life at that. But that’s an easy one – what about a political prisoner – would it be acceptable to trade the life of one agitator for the lives of millions? Or what about just a single person with no stain on their soul – could you pull a random stranger off the street to be executed, knowing that their death would save millions of lives? Or for that matter, what about a person who would be willing to volunteer sacrifice themselves, but who would be unable to sacrifice a stranger.

In each of these cases the trade-off would be exactly the same – one life lost in exchange for millions saved. So one might think that the decision would be equally easy to make in every case. In each of them the Utilitarian answer would almost certainly be that millions of lives outweigh a single life, no matter how “good” that life might be – the millions to be saved would almost invariably include others just as good as the person to be sacrificed, and likely many better. But how many of us could bring ourselves to condemn a good person to death, even knowing the benefit that would come of it?

Something else to consider is that we perceive the values of lives differently depending on whose life it is – the life of a loved one is almost certainly going to be more valuable to any of us than would be the life of a stranger; just as in the example given earlier, the life of a political prisoner would likely seem more valuable than that of a mass murderer. If you feel a little queasy with these choices you’re not alone – there have been any number of psychological studies showing that many would find it easier to passively let a death take place than to actively cause one, even if the net result was the same in both cases. So Utilitarianism might make sense logically – but as these examples show, it would be mighty hard to put into practice in the real world.

So – even in a relatively simple reckoning it seems there are some problems with Utilitarianism, and a lot of problems are a lot more complex. Take the controversy over torture – when (if ever) is it OK to torture a suspected terrorist to gain information that might help to avert a future attack? Or is it OK to assassinate enemy nuclear scientists to delay a nuclear weapons program? These, on first glance, would appear to be susceptible to utilitarian examination, but it’s a hard calculation – perhaps an impossible calculation – to perform.

Consider – torture might not kill a person, but how do we calculate their suffering today, not to mention the longer-term emotional impact? And yes – someone who’s planning on killing innocent civilians in a terrorist attack might not warrant a whole lot of sympathy, but it seems likely that a number of innocent people have been detained and tortured under the belief that they are terrorists. And not only that, but there is also a school of thought that no matter how bad the person being tortured might be, the act of torture itself diminishes all of us who participate, even if our participation is only in tacitly supporting those who perpetuate the torture. Just as John Donne said that “Any man’s death diminishes me, because I am involved in Mankind” we can also say that anyone’s bad actions diminishes us because we are part of the society that permits – even encourages – those actions.

The bottom line is that many actions have moral and ethical dimensions that are not necessarily susceptible to utilitarian calculation – we deceive ourselves and others (if we are communicative about our opinions) if we try to pretend that a simple solution – the greatest good for the greatest number – is a universal solution to every quandary.

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But with all that we do, perfect safety is an oxymoron, sad to say. Or, in the words of my master’s advisor, “The most dangerous thing that happens to all of us is being born – it has a 100% fatality rate.” So, as with any search for perfection, a quest for perfect safety is doomed to failure because something will get each of us at some point. The idea, then, should be to try to push back that point as far as possible while remaining in the best health possible until then. And, I guess, to try to balance our quest to extend our lives against our desire to have a life that’s worth extending – wrapping up in bubble wrap and locking the doors might reduce risks, but it also reduces the opportunities to enjoy, appreciate, and experience life.

It’s hard to develop cirrhosis of the liver, for example, if you never drink – but then you miss out on the experience of savoring a fine wine, of sharing a beer with buddies after work (or during a big game), or the relaxation (and light buzz!) from a snifter of good cognac or a sip of single-malt scotch. For us to try to minimize the risk of liver impairment we’d have to give up the possibility of these good experiences – only you can decide for yourself if it’s worth it to add, say, a few years of life at the expense of several decades of (responsibly, of course) enjoying the occasional drink. And similarly, we can reduce traffic mortality by slowing down – at 5 miles per hour the risk of a fatal traffic accident is vanishingly low – but we sacrifice whatever we might have done in those extra hours spent on the road.

OK – so what we eat and drink, how safely we drive, and so forth are individual decisions that have scant impact on anyone else (except maybe some frustrated passengers and fellow drivers). But what about risk reduction on a societal level? For example, a recent report notes that the US is backing away from its goal of scanning 100% of all cargo containers entering the nation. Acknowledging that uninspected cargo containers are a good way to smuggle in people or weapons, Customs and Border Protection (CBP) also acknowledges that there are simply too many containers entering the country for them to have a reasonable way to scan them all. Or, rather, than a 100% scan rate is possible, but only if we hire a LOT of inspectors, develop and deploy expensive (and not 100% reliable) technology, or impose unacceptable delays on commerce. It could be that the financial and societal cost of 100% security in this area is unacceptable – we can do our best within limits, but there are limits.

What it comes down to – individually and collectively – is trying to strike a balance between quality and quantity. For example, if my doctor told me that cutting beer and potato chips entirely out of my life would add 10 years to my life I’d probably give up both. On the other hand, if he told me that it would make a difference of only a year I’d probably choose to enjoy these treats and however many years I have left. My guess is that we all have some sort of way to determine where our own balance point lies, whether we’re talking about diet, exercise, safe driving practices, going to the doctor, or whatever. Having said that, I’m also sure that our balancing act probably isn’t grounded in accurate facts so much as our gut feel and personal preferences – and unfortunately these don’t always lead us to an optimum solution. What would be nice would be if we – individually and collectively – took the time to try to understand which of the multitude of risks we face are really significant and which of the protective actions we consider taking are really effective; and hopefully to avoid worrying about risks that are minuscule and to avoid taking protective actions that, however good they might make us feel, are ineffective.

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On another topic, I recently posted a piece about a graph that seemed to show the Iranians were using computer models to simulate a nuclear weapon – I mentioned that the graph was way off and that it suggested the plot might be an attempt to spread disinformation about an Iranian nuclear weapons program. It turns out that the curve itself is likely accurate, even if the axes are mis-labeled. In short, the plot may well represent Iranian progress towards developing nuclear weapons, and I may have been premature to dismiss them.

Finally – I apologize for missing last week’s posting. I just started a new job and the transition kept me a bit busy.

The post Safety appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The KEK power plant (Dr Y’s photo)

In 2009 I was asked to travel to Kosovo to give a talk at a UN conference on climate change – my participation was no doubt due to some wrangling on the part of some of my former students at the American University in Kosovo since I’m not a climate scientist. I’ve got to admit that I was intimidated – I’ve given talks at conferences of radiation safety specialists, geologists, and even astronomers, but they were all scientific papers on topics I understood well, and they were given to audiences that I had some sort of academic connection to. This conference was different in that climate change is outside my academic expertise, and the intricacies of the Kyoto Protocols are even further from my comfort zone. So I spent a lot of time trying to figure out what in the world I could say that would be worth the expense of flying me to Kosovo, not to mention what would be worth the time of those in the audience. What occurred to me was that it might be interesting to try to answer the question “What can I tell someone in Pristina that would convince them to take actions that will help the Dutch a century from now?” Or, put another way – why should the residents of the poorest nation in Europe spend time or money today that might help to address a problem that won’t affect them and that probably won’t have much of an impact for decades or longer?

What occurred to me was that maybe we can think of carbon dioxide emissions (or, rather, the actions that lead to them) as a bad behavior – along the lines of smoking, drug use, drinking, overeating, and so forth. Let’s face it – we choose to drive gas-guzzling cars (or not), we choose to crank up the heat or air conditioning (or not), we choose to elect officials who believe in taking actions to curb greenhouse gas emissions (or not), and so forth. To some extent, the carbon dioxide and methane entering the atmosphere are a result of billions of individual decisions made on a daily basis.

So if we think of greenhouse gas emissions as a bad behavior then we have to ask if governmental policies can change these behaviors. And I’ve got to say that the track record is somewhat mixed. Governments can set policies to help address society’s behaviors, but only if the population supports these policies. Consider, for example, the wild success of the government’s Prohibition policies in the early part of the last century. The recent New York City restrictions on large sodas probably won’t have much of an impact on obesity or diabetes, and the War on Drugs hasn’t done much to curb drug use in the US. There are successes of course – consider the reductions in smoking over the last few decades – but the bottom line is that unless the citizens buy into a policy it probably won’t work. So what can we do to get the Kosovars to buy into reducing greenhouse gas emissions?

One of the first things I noticed when I landed in Pristina the first time was the torrents of smoke belching out of the KEK lignite-burning power plant. Replacing the plant would be a good start, but anything to reduce electrical demand would be a good start. So maybe a place to start would be finding a way to reduce electrical consumption – and maybe starting with lighting.  The problem is that mandating that all Kosovars replace their incandescent lights with compact fluorescent or LED bulbs probably wouldn’t work because these bulbs aren’t cheap – we still have the question of how we get poor people to voluntarily take (and support) actions that won’t directly help them. But maybe one way to do it is to turn this into something that will help them, and to point this out.

So what would happen, I asked my audience, if KEK were to pay for the energy-efficient lights and deliver them to their customers? The bulbs would use less electricity, so KEK’s customers would see lower electrical bills while simultaneously reducing their greenhouse gas emissions. And if KEK were to pay the up-front costs (perhaps borrowing money to do so) then the consumers wouldn’t be out any money at all – they’d just see a lower electrical bill. But I thought it was important to stress that the bulbs were not a gift, because people don’t always value something that’s just given to them. And here it gets a little complex, but not too bad….

Say KEK spends €100 to replace all the light bulbs in my home with compact fluorescents – KEK is a business and they can’t just donate this much money to every home in their service area. So the money KEK spends on light bulbs could be repaid by KEK’s taking some of the money from energy savings from each customer each month – if my electric bill drops by €20 a month because of the new lights then I’d get €15 and KEK would get the other €5 until the lights have been paid for. Taking this a little further, KEK could also sell carbon credits to reflect its reduced emissions, and could split that cost with its customers as well. The customer saves money every month, KEK gets repaid, and carbon dioxide emissions are reduced – everyone wins. And maybe if the initial program is a success KEK could expand it to include kitchen appliances, air conditioners, and furnaces – within a decade or so Kosovo could reduce its carbon emissions by a third, and KEK might be able to replace its lignite-burning power plants with something cleaner.

The other part of this would be to make sure the customer can see – every month – that what they’ve done is benefiting them. A great way to do this would be to make it explicit by including it in every electric bill – to show the energy usage and cost, to include a line showing how much money was saved by changing light bulbs, and to show how much money was saved by selling carbon credits (less the loan repayment to KEK). If my electric bill has a line telling me each month that I’ve saved €15 then I’m thinking that I’ve saved enough to buy a small gift for my wife or to take my kids out to lunch. Closing the loop like that – showing me that letting KEK replace my light bulbs with more energy-efficient models puts money in my pocket – helps to reinforce my good behavior and encourages me to keep up the good work.

This approach can be expanded a bit further, should the government choose to do so. They can, for example, use similar tactics to encourage upgrading windows, insulation, and other upgrades to reduce wasting energy. Or they can help contractors (and customers) to upgrade construction of new buildings to meet higher conservation standards – the cost of some of these measures could be defrayed by charging a small tax on energy bills of those buying the upgraded properties.

So one way of implementing this on a national scale might be something like this:

• Government announces a policy on energy efficiency
• Government loans money to KEK to finance implementing this policy (e.g. buying energy-efficient items (e.g. lights, appliances, windows, etc.) for their customers
• KEK purchases and installs new these items for its customers
• Customers see lower energy bills and repay KEK
• Greenhouse gas emissions go down in Kosovo

I’ve got to admit that I tend to be a bit of an idealist – I’d like to think that people will do the “right thing” simply because it’s the right thing to do. But I also know that’s not the way the world works – idealism is nice, but it’s more effective to be rewarded for your actions. So why not be rewarded for doing the right thing – especially in a poor nation that has little immediate stake in global warming? And what better way to get citizens’ support for a government policy than by showing them real benefits every month?

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Sailors decontaminate the Reagan’s flight deck.

In that relatively dead news time between Christmas and New Years the San Diego Union-Tribune reported that 8 sailors from the USS Ronald Reagan were suing the Tokyo Electric Power Company (TEPCO) on the grounds that TEPCO had covered up the severity of the Fukushima accident and that, as a result, the sailors had been exposed to dangerous levels of radiation. The sailors are suing for $40 million each (and for a baby born to one of the sailors after the exposure) plus another $100 million for anticipated future medical bills.

The Reagan spent time off the coast of Japan providing humanitarian assistance after the earthquake and tsunami. It is likely that the ship was exposed to contaminated air and less likely that it was exposed to contaminated seawater – the article also mentions that decontamination activities took place onboard and it includes a nice photo of sailors decontaminating the flight deck.

The sailors are claiming that they suffered from physical pain, mental anguish, migraine headaches, weight loss, ulcers, rectal bleeding, and lapses of concentration and their lawyer claims that they’ll need to have bone marrow transplants and chelation therapy (chelation agents help to scavenge metal ions from the body) and they feel that their lives will be shortened. And apparently ready to testify on the sailors’ behalf, is a toxicologist quoted as being ready to stake his reputation on all of this.

Personally, I feel a little badly for the toxicologist whose reputation is at stake, if he’s ever named in public. Here’s why.

First, let’s talk about the symptoms. Radiation sickness can cause blood problems – in fact, the blood-forming organs are among the most sensitive in the body to radiation – but the radiation dose at which the very first blood problems occurs is about 25 rem or so. Bleeding can happen as well, but that takes considerably more radiation exposure – about 700 rem and higher. Bone marrow transplants have been given to radiation accident victims, but not until they have several hundred rem worth of exposure. By the time a person is developing neurological symptoms they have typically received a fatal dose of radiation (in excess of 800 rem) and they don’t have long to live. I’ve not heard of radiation being responsible for ulcers, but I do know that the epithelial cells that line our digestive tracts are sensitive to radiation – gastro-intestinal syndrome starts to kick in at doses of about 1000 rem. And – key to all of this –these happen after acute exposure, in which the exposure takes place in minutes to hours; not over a period of days or weeks. The fact that these sailors are still alive nearly two years after their exposure strongly suggests that their symptoms are not due to radiation exposure.

By now it should be obvious that the key factor in a radiation injury case is the amount of dose to which a person was exposed, and the article cited earlier doesn’t give any indication of the dose to which the sailors were exposed. I can make an educated guess (and I will), explaining my reasoning, but it would be really nice to have a dosimeter reading to hang my hat on. But let’s take a crack at it…and remember that we’re not trying to figure out if the sailors were exposed to, say, 0.1 rem versus 0.2 rem but, rather, whether or not they were exposed to the hundreds of rem that would be needed to cause the symptoms cited.

The Navy claims that the sailors were exposed to “less than the radiation exposure received from about one month of exposure to natural background radiation from sources such as rocks, soil, and the sun.” This comes out to about 30 mrem, or about 3% of a rem. For a number of reasons this number seems reasonable to me – here’s why.

First of all, let’s think about how much radioactivity there will be 100 miles out to sea. A lot of radioactivity entered the ocean, and it’s quite possible that some of this made it to a distance of 100 miles during the time the Reagan was on station. But – without wanting to sound trite – it’s a BIG ocean and the radioactivity dilutes quickly.  In fact, seawater samples taken only a handful of miles offshore came up with barely detectable levels of radioactivity – it seems unlikely that the ocean the Reagan was sailing through would be so heavily contaminated that it could cause injury to the sailors in question.

Of course, a lot of activity was released into the atmosphere and a lot of this blew out to sea. But there’s a lot of atmosphere out there as well, and the Reagan is a pretty tiny speck in it. With shifting winds the plume is unlikely to have blown directly over the Reagan for extensive periods of time, not to mention the dispersion of the plume as it traveled out to sea. I was less than 20 miles from the reactors for three days, smack in the middle of the area that was most contaminated, and I was in Tokyo (about 150 miles away) for a week. I picked up more radiation on the plane flight to Japan than I picked up during my time in Tokyo, Fukushima, Soma, Iidate, Sendai, and Minimasoma. And by my calculations, people living in these areas wouldn’t receive enough dose to ever develop radiation sickness. So it doesn’t surprise me that contamination might be measurable on the Reagan, but only because we have the ability to detect vanishingly low levels of radioactivity – just because we can detect it doesn’t make it harmful.

On top of this, I’d also like to talk about Naval nuclear power – a program in which I spent 8 years of my life. I don’t think that many in civilian nuclear power would argue that the Navy’s program is the best in the world. And I know that it took me several years to de-program after leaving the Navy – to realize that the tight standards we had on-board were a bit excessive in a non-military setting. Many of our standards for radiation exposure, allowable contamination levels, radioactive materials security, and so forth were far more stringent than what is required by law in the US. Every Naval nuclear vessel is packed with radiation instruments – Geiger counters, air samplers, smear wipes (to look for removable contamination), and more; as well as automatic air samplers that alarm when airborne radioactivity levels rise too high. Not only that, but Naval crews are well-versed in contamination control, decontamination, using their instruments, and much more. On my submarine we practiced weekly for radiological emergencies and we used our instruments daily.

This is just a long way of pointing out that the Navy radiation safety technicians are very good at their jobs, even when there’s nothing going wrong. And when they know they’re being exposed to contamination they step up their game. My submarine was at sea (in proximity to the Soviet Union’s Pacific coast) in 1986 when Chernobyl blew – we received a radio message instructing us to take air samples every time we ventilated with outside air to look for excessive airborne radioactivity. We found elevated levels, by the way, but not nearly enough to be a concern.

So for all of these reasons – the huge amounts of dilution into the air and water, the relatively low radiation dose rates I (and many of my colleagues) measured on the ground (and in the air) in Japan, and the overall high quality of the Navy’s radiation safety program – I find the Navy’s assertion that the sailors in question were not exposed to even 1 rem of radiation to be very reasonable. In fact, any other answer would surprise me immensely.

So what’s happening with the sailors if radiation’s not the question? Well, I’m not a doctor and I can’t give a medical opinion on this – especially when I’ve not met any of the people and when all I have to go by is a short newspaper article. I have no doubt that they are suffering, just as I have virtually no doubt that they are not suffering from radiation exposure. And the fact that the radiation exposure needed to cause the majority of their symptoms is almost invariably fatal (and the fact that they’re all still alive to bring their lawsuit) strongly supports this assertion. I feel badly for these sailors – but I sincerely hope that their lawsuit fails. Being worried and anxious and playing on the fears and ignorance of the public and the legal system is not a reason to strike it rich, and TEPCO (regardless of their mistakes) should not have to pay for damage that they did not cause.

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On the face of it the question sounds sort of nutty – obviously the world and the universe we see around us are real because we interact with our world and we observe the universe directly. How, for example, can I deny the reality of the keys I am now typing on, or the solidity of the chair I’m sitting on, or the sight and sound of the television program I’m watching. On the other hand….

First, consider that what we consider “solid” objects are mostly empty space – well over 99.9% of the mass in every atom is concentrated in the nucleus, which is surrounded at a relatively great distance by the electrons. The volume of an atom taken up by the nucleus is minuscule – an analogy has been made to a fly buzzing around in the Astrodome. Every bit of “solid” matter with which we interact is almost entirely empty space. And the solidity part is also interesting – when I walk across the floor (or sit in my chair or grab onto a glass) the contact between my fingers and the solid object is actually the electrostatic repulsion between the outmost electrons surrounding the atoms that comprise my fingers and those surrounding the outermost electrons in whatever it is that I’m holding or walking or sitting on. So the reality of the solid objects in our lives is sort of shaky – the apparent solidity is as much illusion as it is reality.

So – solid objects are really mostly empty space and contact with a solid object is really just electrons repelling each other. But beyond that, there is also ample evidence that what our senses tell us is a sort of edited reality – our brain, for example, fills in the gaps in our vision to show us what ought to be there, even if some visual information is missing. Not to mention that our brain helps to filter out extraneous noise – all of our perceptions of the world around us are filtered through our nerves, our central nervous system, and the way that our brains process all of this information. For all we know, we could be living entirely within our heads with our brains simply imagining all of our interactions with the world – a sort of self-contained Matrix-like universe. Having said that, I doubt that this is the case, but on the other hand, I know that I’ve had some pretty realistic dreams – who’s to say how much of what I think I sense is actually illusory. The only way to make sure is to think of a sort of test to help differentiate between the universe we all think we live in versus one that exists only in our minds. Beane, Davoudi, and Savage note (as have others) the dramatic increases in computer capabilities over the last few decades and, projecting these trends forward, have come to the conclusion that the computers of the not-so-distant future are likely to have the capability of simulating an entire universe – including its inhabitants and their thoughts, feelings, and sensory perceptions.

So let’s get back to the paper mentioned at the start of this posting. Going back a decade, philosopher Nick Bostrom published an interesting paper in Philosophical Quarterly in which he offered three suggestions and argued that at least one must be true: that humanity is likely to go extinct before reaching a “posthuman” stage, that posthuman civilizations are unlikely to run computer simulations of their past, or that everything we consider to be our reality is in actuality a massive computer simulation. And of these possibilities, Bostrom suggests there could be a whole series of nested computer simulations (i.e. the “real” species simulates a universe on their computers and virtual beings in that universe write their own simulation, and so forth) and further suggests it is unlikely that we are at the head of this chain. To Bostrom it is more likely that we and the universe we see around us are computer simulations (possibly one level of a long series of simulations) than that we are at the head of the line. Beane, Davoudi, and Savage’s paper posits ways that Bostrom’s suggestion can be tested.

I’ve got to admit that I can’t follow the mathematics or most of the physics employed by Beane and his colleagues – to some extent I’ve got to push the “I believe” button and to assume that their math and science are solid. And the one example that I am familiar with is intriguing – they suggest that some irregularities we have observed in the distribution of energies among the most powerful cosmic rays could be an indication that what we perceive as reality might be a computer simulation.

So we’ve got to ask ourselves – does it matter if we are “real” or if we inhabit a sophisticated computer simulation? I’ve given it a lot of thought and, to a large extent, I’ve concluded that it doesn’t matter much to me. Whether “real” or virtual, the universe I inhabit seems to make sense; it’s all that I know, it seems to work and to make sense, and it seems to be self-consistent. If this is a simulation, I can’t tell the difference between it and reality. If it turns out that Beane and his colleagues are correct then we might someday figure it out – maybe even (as they put it) “for the simulated to discover the simulators.”

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On another note, this will be the last ScienceWonk posting of 2012 as I’ll be taking next week off. Happy Holidays, everyone, and thanks for taking the time to log in, read, and to post thoughtful comments!

The post Reality? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The attraction of this approach is that we can say the hell with convention – we know what’s right and we’re going to achieve it in the most efficient way possible. The problem is that those who take this approach are assuming that their judgment is better than that of society, and they are assuming that the end they are after makes their methods acceptable after the fact. But what if they’re wrong? What if the harm the anti-hero does to society by his disregard of the rules turns out to be more significant than the good that is accomplished?

Earlier this week Eddie Walsh, a journalist, scholar, and FAS affiliate published a thought-provoking piece on the increasing use of drones by the World Wildlife Fund (WWF) to help attack the practice of poaching in Africa. Walsh points out that the WWF – along with other NGOs – is taking it upon itself to deploy assets to curb crime in a foreign nation. And, like the anti-hero, the WWF may have a noble goal, but what if their means cause more harm than the good they accomplish?

First let’s talk about the good – the WWF has legitimately good aims, to reduce poaching. The people they’re after are criminals and the animals they’re shooting are endangered. With the exception of the poachers and their customers there are few who would argue with the WWF’s aims.

On the other hand, we do have to consider the collateral damage that can arise. Walsh points out, for example, that the poachers (or others affiliated with them) might decide that anyone working with the WWF is fair game, which could put the entire WWF organization at risk. But it can go beyond that – what if NGOs all start to become targets? After all, there are many who view NGOs and those who work for them as pesky meddlers who need to be kept in line. It’s a hard trade-off – real benefits today (less poaching and fewer poachers) versus hypothetical harm in the future – but it’s one that has to be considered.

The WWF approach has another potential downside – it reduces respect for the nations in which they are flying their drones. What does it say about a nation that has to rely on foreigners – private citizens at that – to help enforce its laws? Does this reduce respect for the nation? And for that matter, what does it say for a nation that it allows a foreign NGO to fly drones over its territory? Our drone attacks over Pakistan have aroused the ire of the Pakistanis; one can’t help but wonder what a nation – and its citizens – think about an NGO flying drones, however noble the intent, over its territory. At the very least it’s likely to reduce respect for the government on the part of citizens and rivals alike. Is there potential collateral damage stemming from the use of drones on the part of a non-governmental organization?

But there’s more to consider. Today, the WWF is using its own drones to help catch poachers, but what about tomorrow? Will GreenPeace use drones to track whaling vessels, the better to interfere with their operations? What about the Red Cross, checking on victims of a hurricane – or political prisoners? What about your local neighborhood watch, tracking local sex offenders – or whoever else triggers their interest? Or, for that matter, what about a government that hires an NGO (directly or indirectly) to look for people of interest – like maybe citizens who are tired of being oppressed? At what point does doing good turn into doing bad?

To be honest with you, I hate “slippery slope” arguments because you can turn just about anything into a slippery slope into something nefarious. At the same time, slippery slopes exist, and any transgression makes the next one that much easier to rationalize and to commit.

I honestly can’t say exactly what I think about the thought of an NGO deploying drones to help accomplish its aims. I admire the dedication exhibited by the WWF, and I respect their aims. The world will be a poorer place if poachers kill the world’s last wild rhino or the last snow leopard. But the world will also be a poorer place if there is an open season on NGOs, if nations abrogate their responsibilities to private groups, or if the technology used to do good is turned to more dubious ends.

The problem with being an anti-hero is that is requires you to be right all the time. When you decide to ignore rules (or societal convention) and take it upon yourself to do the right thing – in spite of what societal rules might call for – there isn’t much room for error. I’d hate to see a world without large game – but I’d also hate to see the neighborhood watch drones overhead every time I go outside, and I’d hate to see NGOs become targets of those who fear their meddling. It’s nice to think of well-intentioned private groups who are so dedicated to their work that they are willing to risk arrest to do good – but we have to make sure the potential costs aren’t higher than we can live with.

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When I first saw this plot I was surprised at the calculated output – our first nuclear test was a fraction this size, as have been the initial nuclear tests of every other nuclear power. To think that the Iranians were already looking at a 50 kT device was a surprise. But the shape of the graphs seemed reasonable, the time scale seemed in line with what I’d expect, and the article quoted some well-known scientists and organizations who took the plot seriously. I looked at the plot, read the commentary, and it reinforced my suspicions that the Iranians are continuing to work on nuclear weapons. In my mind, it all fit together into the mental picture I’ve been assembling. And then I went back to work.

Yesterday, then, I was sort of surprised to read a snippet that said the graph was wrong. Skimming the article I read a line that mentioned one of the scales was off by a factor of a million and, looking at the plot, I immediately saw the problem (for those of you who are wondering…the numbers on the left axis are in units of kT per second – you get these numbers when you divide the yield (in kT) by the time shown on the x-axis (in seconds). And the numbers are about a million times higher than they ought to be. Dividing 50 kT by 2 microseconds should give a value of about 25 million – not 25 trillion as shown on the plot. Blindingly obvious when you’re looking at the plot and checking it for flaws – but nothing that’ll jump out at you unless you’re looking for mistakes. What I saw – and I’m willing to bet that what most people saw – were two lines that seemed to have the right shape, a surprisingly high (but by no means implausible) yield, and about the right time span. Since so many things seemed right about the plot – and because it fit my assumptions – I never thought to check the math. Bummer.

So – one thing that’s interesting here is that I (and apparently a number of others) were inclined to accept this plot without a whole lot of checking because it fit our expectations. Consider – if I see a horse-drawn carriage in Central Park it fits my preconceptions of the sort of thing you see around Central Park, and I’m likely to assume that whoever’s in the carriage is a tourist. If I take a quick glance and see a couple snuggling under a blanket it only confirms my preconceptions – but I’ll probably never go up to ask to peek at their drivers’ licenses to make sure. We are all very ready to gloss over details as long as the big picture matches our expectations.

Part of this is almost certainly due to our evolution as a species that profited from pattern recognition – recognizing patterns helped our earliest ancestors to make sense of the world and to survive. So recognizing that really big bears lived in caves helped them to avoid becoming cave bear chow, just as recognizing that inserting a spear into in the right spot on a mammoth could lead to dinner. Once we have recognized a pattern, that expectation becomes a sort of mental short-cut that lets us save time (or to stay alive) – pattern recognition is engraved in our DNA.

The problem is that it works too well and sometimes leads us to see patterns that don’t exist. Our expectations about Saddam Hussein helped us to see evidence of a WMD program that didn’t exist. And my expectations that Iran might be developing nuclear weapons inclined me to believe the authenticity of this plot.

Our expectations aside, it’s still interesting to think about the plot, where it came from, and what it might mean.

Take the simplest thing – this was almost certainly not the product of a computer program because a computer would never have made the mistake of being off by a factor of a million in a simple calculation. The plot looks to have been printed with a computer and printer, but the values in the left y-axis were probably entered by hand rather than by calculation. This, in turn, suggests that whoever put this plot together (and leaked it to the AP) was likely not a scientist or an engineer – it’s not as hard as you might think to be off by a factor of a million, but that sort of mistake usually doesn’t make it past the first line of review. So this plot seems most likely to have been put together by a non-scientist, perhaps using information provided by scientists or maybe one who read enough to get the superficial generalities (the stuff that caught my eye) right. If this plot was really constructed by Iranian scientists then I’d have to question their ability to design a working nuclear weapon – but it seems more likely that this was never in close proximity to a scientist. Or at least, not one who bothered to check the math (and if this is a “real” plot then we might not have to worry as much as we have been about Iranian nuclear weapons!).

Of course, if the plot wasn’t developed by a scientist then we’ve got to wonder who made it up, and why. Was the intent to discredit Iran? To justify an attack against Iran? To push the US and Europe into additional sanctions? To help Iran dissuade potential attackers, or to help Iran look stronger and more advanced than they really are? To make it looks as though Iranian nuclear scientists are inept? To put it another way – was this plot propaganda against Iran, disinformation put out by Iran, or something else by a person (or nation) with a political agenda? Not sure that we can pin that one down now, but it would be nice to know.

Whatever happened – and whoever was responsible – this gives me pause. We have made similar mistakes in the past – letting our tendency to see the patterns we expect, swallowing information that fits these biases, and drawing conclusions about a nation we really don’t like much – and made some mistakes. If this plot is authentic and there’s a simple mistake in the plotting then we have to worry about Iran; if the plot is fabricated to help nudge us along a path to war then we have to worry about whoever is doing the nudging, and about our seeming inability to learn from past experience. But for me, seeing this plot makes me wonder if maybe Iran isn’t running into some snags – are they trying to convince us that they’re farther along than they really are, or is some other nation so disappointed in their ability to find a smoking gun that they’re manufacturing “evidence” of wrong-doing? Either way, it makes me more inclined to hold fire until we can find something more definitive.

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• To form a more perfect union,
• To establish justice,
• To provide for the common defense,
• To secure the blessings of liberty,
• To promote the general welfare, and
• To insure domestic tranquility.

While these are all worthy goals, for the purposes of this posting (and to avoid stepping too far outside my realm of expertise) I’d like to look primarily at the penultimate function – to promote the general welfare – in the context of issues that are strongly dependent on science and/or technology.

In 1963 Kenneth Arrow (who was awarded the 1972 Nobel Prize in Economics) wrote a fascinating paper (Uncertainty and the Welfare Economics of Medical Care) in which, among many other observations, notes that medical care is complex and requires a high level of knowledge and understanding in order to stay informed and to make informed decisions. For this reason, the patient “does not have the knowledge to make decisions on treatment, referral, or hospitalization” and must delegate many of these decisions to the physician. Of course, anyone can call themselves a physician, and it is not always easy for a patient to figure out who is (or is not) competent – for this reason, it is reasonable to insist that anyone calling themselves a physician be able to back up their claim. In this case, government helps to “promote the general welfare” by requiring people to demonstrate a minimum level of knowledge and training in order to be called a physician, and the government can remove these credentials if a person proves to be unworthy of the special trust awarded to those of us put our health and our lives in their hands.

There are many more reasons than this to read Arrow’s paper, but I’d like to extend this particular thought beyond medical care into other areas in which, to use Arrow’s term, “information inequality” can be a significant factor in being able to make a good and informed decision on matters of importance.

Consider, for example, how many of the questions facing society are grounded in science – and how many of these questions can only be addressed by using scientific knowledge and methods. How much lateral acceleration should a solvent-carrying pipe be required to withstand, for example? How much (if any) chlorine and fluorine should be added to our water supplies? To what cleanup standards should we remediate a contaminated site – and does it make a difference if the site is in the wilderness, in a slum, beneath a city park, or outside a factory? None of these decisions can be made without first looking at the underlying science – how dangerous is the solvent, what are the benefits and risks of adding chlorine and fluorine to the water supply, what is the risk from a contaminant and how much are people (and animals) exposed to it, and so forth. Without a solid grounding in the science underlying an issue we might make a good choice, but it’s likely to be by chance rather than by design. This is where government comes in, pursuing its mission to promote the general welfare.

During my student days I used to get into some great discussions with, of all people, my favorite hot dog man on campus. A staunch Libertarian, he would good-naturedly attack me for my job working in the state health department – his refrain was always to let the marketplace sort out all of these issues. I suppose that he thought this would happen by the public realizing that, for example, patients of a bad radiologist would parade their skin burns and warn others away, or that a cluster of cancers around a radioactively contaminated site would lead potential customers to eschew one brand of home appliances in favor of another. But there are a few problems with this approach.

One problem is that you have to create pain and suffering – victims – in order for market forces to begin to kick in; I’d like to think that the general welfare is better-served by preventing needless illness and death rather than using it as a warning. Another is that many of the risks we face are subtle – radiation-induced cancer might affect only a small fraction of those exposed and might not show up for decades after an exposure for example and teasing out the cause of a subtle health effect with so long a latency period requires the time and patience (and funding) to do a long-term study as well as the ability to interpret the results. For the marketplace to be able to identify health effects such as radiation-induced cancer the interested citizens would have to either school themselves in the intricacies of epidemiology, biology, and radiation science or they’d have to find one or more professionals to perform this study on their behalf. What government can do in such a case – where any rational decision requires specialized knowledge and skills – is to provide the citizens just this sort of professional study and scientifically based guidance.

Over time I came to view my role (and that of many of my colleagues in government) to be just that. Given that we cannot reasonably expect the majority of the public to have the specialized education, skills, and experience to make informed decisions on most (or even all) of these science-intensive issues, I saw my job as helping to fill in these gaps in order to help promote the general welfare. And not just my job – that of my colleagues in many other agencies as well. I know that I don’t know much about, say, asbestos – but luckily there’s a bunch of scientists and regulators at the EPA (and various state agencies) who DO understand it and who can help make sure that my family and I (and you and your family!) aren’t exposed to harmful amounts of the substance. Similarly, I don’t know much about restaurant sanitation, and I certainly can’t insist on inspecting kitchens or food processing plants before I sit down to dinner. But, again, that’s OK because I don’t have to be an expert – I can rely on government inspectors to have this level of expert knowledge. In fact, much of government provides these services on our behalf, and I would argue that the general welfare is improved as a result.

Now – lest I be accused of being a big government type – I also think that there are places where the government over-reaches. Some regulations are needlessly restrictive, some agencies are needlessly confrontational, and there is no doubt that all levels of government wastes a lot of time and money. But a lot of what government does is to help put us – the citizens – on a level playing field with businesses who, whether maliciously or not, would otherwise be able to take advantage of this information inequality.

Finally, I also feel obligated to point out that science should be the foundation and the starting point for decision-making in many of these complex areas, but it should not be the last word. As a scientist I can, for example, calculate the amount of radiation exposure that will result from a given amount of radioactive contamination left in a building after a terrorist attack. I can even calculate the risk that this radiation poses to those who are exposed to it, and I can give you my best scientific opinion as to whether or not this should be considered an acceptable risk after also considering the cost of further cleanup and other factors. But I can’t necessarily tell you that society should accept this level of risk because that gets into areas in which I am not qualified to address. I can’t, for example, do more than guess at the social and psychological stresses from living in areas that, while acceptable to me as a radiation scientist, are frightening to a non-professional. I also can’t assess whether or not the cost in lost tourism revenue will be more or less than the cost of additional cleanup, and my science won’t help me to determine the issues of fairness when government promotes cleanup standards and apportions aid to those afflicted. None of these decisions can be made without informed scientific input, but none of these questions can be solved with a calculator.

So – to bring this to a close, I’d like to go back to where we started and to briefly summarize. The purpose of government, among other things, is to provide for the safety and happiness of the governed and to provide for the general welfare of a nation’s population. One of the ways that we do this is by developing and promoting safety standards, including in areas that can be quite scientifically complex. For that reason, it seems to me entirely appropriate to ask that government help the governed by having knowledgeable professionals develop solid science-based guidance that can form the basis of regulations that are (hopefully) protective of the public welfare without being needlessly restrictive or expensive. Idealistic? Well…a bit, particularly because of the adjective – “needlessly” – which is open to interpretation. But if science can at least get us to through the quantitative parts (what can be crunched on a calculator) then hopefully the problem can be turned over to those who are more skilled with the non-quantitative aspects of the problem to come up with a solution that might not make everyone happy, but that will at least irritate as few as possible.

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In a nutshell, the Precautionary Principle states that, if something is potentially harmful and it is not fully understood then we should assume it is harmful until it is proven otherwise. It is akin to the Hippocratic Oath – the part that admonishes physicians to “first do no harm.” But the Precautionary Principle is sort of one-sided as usually applied, and this is what I wanted to explore in this post.

Let’s start off with a rather simple one (and the one I know best) – exposure to radiation. First, there is no doubt that radiation can be harmful – we all know that it can cause cancer and, in higher doses, birth defects and radiation sickness. Most radiation scientists (myself included) would also agree that we do not yet know everything there is to know about radiation’s health effects. So a strict adherence to the Precautionary Principle would seem to suggest that we avoid all radiation exposure – that until we fully understand the impact of low-dose radiation we should simply avoid it altogether. But does eliminating ALL exposure to radiation really minimize our risks? I would suggest not.

Consider medical radiation, for example. When I worked in medical radiation safety we provided support for nuclear medicine, radiology, and radiation oncology. In each of these departments patients were exposed to radiation – which we know to be potentially harmful in sufficiently high doses – in apparent contradiction to the Precautionary Principle. Leaving aside for the moment the fact that a large fraction of physicians can’t quantify the risks of medical radiation to their patients, it’s reasonable to wonder about the possible longer-term health effects of this exposure. Are we putting patients at risk by prescribing these procedures? Should we outlaw medical radiation exposure in deference to the Precautionary Principle? Or is there more to consider?

Obviously the answer to the final question is “yes.” Consider – cancer takes decades to manifest itself, and the risk of developing cancer from radiation exposure is very low (the radiation from a single CT scan – among the highest-dose radiological procedures – carries with it a risk of less than 1/100 of 1%). When my son was x-rayed to try to diagnose the reason he was having problems breathing I accepted this risk gladly because not breathing is far more certain to be fatal, and very quickly fatal at that. My thought was that not breathing is also a health risk and it would be nice to keep my son alive in the short term. Similarly, x-rays can remove the need for exploratory surgery, can help physicians to diagnose disease, and so forth – all of the obvious risks from exposure to medical radiation are matched by obvious benefits. Few would debate the benefits of medical radiation exposure, if used responsibly.

So the Precautionary Principle would seem to be somewhat more complex than phrased above – we can’t simply ask ourselves if something has been proven safe beyond a reasonable doubt. We should also consider the risks of failing to take advantage of something that carries with it a benefit as well as a risk, and we should try to balance these against each other. Or to put it another way, lacking diagnostic information is a risk and, in some cases, this can be a greater risk than the radiation.

Let’s take a somewhat more difficult example – genetically modified organisms (GMOs). On the one hand, while we know a lot about these crops (and there are no indications I know of that links them to human health problems), we don’t know all there is to know. So a number of nations have decided that, in keeping with the Precautionary Principle, GMOs should simply not be sold or consumed within their borders – this way, if research some years or decades hence shows them to be harmful, at least humans were put at risk.

But what if a nation is starving? If genetically modified food is fed to the citizens then they are potentially put at risk – the risk is nebulous and unquantifiable, but it has not been shown to not exist. So many nations have decided that, according to the Precautionary Principle, GMOs should not be fed to even the starving. But withholding food – even genetically modified food – from starving people is certain to cause harm when they succumb to malnutrition and starvation. So what’s a leader to do? Feed his people with food that might make them ill years or decades hence, or withhold potentially risky food from his people? I would argue that, as with my son’s x-rays, the most reasonable course of action is to feed one’s people, even if the only available food is genetically modified. Someone who starves to death won’t live long enough to develop whatever problems might stem from eating genetically modified foods. It would seem to make sense – as with my son – to expose people to an indeterminate long-term risk in order to avert a certain death in the short term.

This makes me wonder if perhaps the Precautionary Principle should be re-formulated somewhat. There is a degree of philosophical purity in simply refusing to allow people to be exposed to a potential threat that cannot be quantified and that might carry a degree of risk. But we might not have the luxury of being philosophically pure, and this degree of purity simply doesn’t hold water when it leads to suffering and death. Weighing a long-term hypothetical risk against a short-term real risk is not easy – but weighing bodies in the street next week against hypothetical patients a few decades hence…that ought to be an easy choice.

Given all this, I’d suggest that the Precautionary Principle might need to be modified somewhat to be a bit less strict and one-sided – to encompass not only the exotic and hypothetical, but also the real and immediate needs of those who might be exposed. Instead of first doing NO harm, perhaps we should simply try to do as little harm as possible.

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Sand swept inland by Hurricane Sandy.

This week’s posting is a bit tardy – in the continuing aftermath of Hurricane Sandy I’ve been helping on the night shift at one of the city’s shelters and, more recently, been helping to check on the occupants of high-rises and housing project buildings in some of the areas affected by the storm. It’s been a busy few weeks and it’s been somewhat thought-provoking as well – I hope you’ll excuse another posting that strays somewhat from my normal line of musing.

The shelter I was working at was hosting several hundred people who’d been evacuated from nursing homes, hospitals, and psychiatric facilities; and it was staffed by a mixture of city workers, volunteers, and a Disaster Medical Assistance Team (DMAT) comprised of medical professionals from Ohio and North Carolina. There were also some AmeriCorps members with us – the AmeriCorps and volunteers helped with much of the work of running the shelter (cleaning, passing out food, accompanying patients who were transferred to other hospitals or nursing homes, helping clean and change incontinent patients, and so forth) – many of the volunteers came from Montana, Washington State, and elsewhere on the far side of the continent. And the shelters aren’t the only place where people have come from a great distance to help us out – a few hours before sitting down to write this I was in Union Square where I talked with an electrician from Ohio and saw utility trucks from Alabama and Kentucky – people who traveled hundreds of miles to help New York City get its electrical grid back up and running. Sure – they’re getting paid for their work. But they weren’t forced to come here – thousands of people agreed to travel hundreds of miles to help us out, leaving their families behind for however long it takes.

At the shelter, I spent some time talking with the DMAT and was struck by their obvious dedication as well as by a comment by one of the DMAT members – that the number and dedication of the volunteers they’d encountered in New York City. The team member with whom I was talking said that he was amazed that, in the big city, there were actually too many volunteers and that they were willing to tackle anything asked of them – even changing adult diapers and collecting the trash. And for my part, I never saw a volunteer try to shirk or avoid anything. Searching the buildings brought me in contact with still more helpers – National Guard from Boston along with more NYC volunteers. And, again, whether carrying food and water to the tops of buildings that had no elevators, gathering information, or anything else that was asked of them. And you hear similar stories over and over – again, even in the big (and heartless) city it seems that at least some people are willing to put themselves out to help others.

At this point there are a number of directions I could try to take this posting. The most obvious would be to marvel at the altruism that lies at the core of even the jaded inhabitants of Gotham. And it is also tempting to discuss the biological roots of altruism – the subject of scientific research over the years. But there’s something else that I think is also worth considering – how we choose to see and interact with the world in which we live.

Anyone who pays even cursory attention can see a lot of bad in the world – all we have to do is to watch the news. It is tempting to look at our wars, murders, terrorism – even at negligent parents (or children) – and to be driven to despair. And from there, it’s not a far stretch to conclude that we just have to stay on guard – it’s harder to be caught unawares if we are constantly on alert for an attack and we can’t have our trust betrayed if we never extend it in the first place. And it makes sense from an evolutionary standpoint – a caveman who’s always looking for an attack is less likely to be killed by a cave bear or an enemy tribe. We most likely evolved to be cautious, suspicious, and to extend trust only grudgingly because that made our ancestors more likely to survive, and those genes would have been passed down to us.

At the same time, humans are pretty pathetic compared to much of the animal kingdom – we’re not very fast, not very well-armored, our teeth are fairly small and dull, we have no claws, and so forth. What we’ve got going for us is our intelligence, our adaptability, and our ability to band together – a group of humans can take down any predator and any game animal, just as a group of humans working together can survive hardships that would doom a group of individuals trying to make it on their own. We are at our best when we work collectively to overcome tremendous odds. Our DNA also inclines us towards altruism and collaboration.

So we find ourselves with competing genetic imperatives – to work together to help to stack the odds in our favor against a world that is trying to kill us, while simultaneously being wary of all of the things (and people) that are trying to kill us. Both of these approaches can be rationalized and understood and both are justified – the question is which we will choose to give the lead as we go through our own lives.

This is more than a “glass-half-empty/glass-half-full” debate, but that really is the basic concept. While the way that we view our fellow humans is flavored by our experiences – by those who have cheated, attacked, threatened, or otherwise wronged us as well as those who have helped us – we do have a choice in how we respond to these interactions. We can choose to assume the worst of others (dominated by our fears of being harmed), or we can choose to assume the best in others (and to put ourselves at risk of harm). But we are not required to see the world – and our fellow humans – as inherently good or bad; it is a choice that we can make.

I’d also like to point out that it’s not just our volunteers and DMAT members who have elected to put the interest of their less-fortunate fellow citizens ahead of their own self-interest. Anyone in law enforcement, anyone who fights fires for a living, our soldiers and sailors, not to mention our teachers, priests, and most of our public servants – these are all people who are talented enough and who work hard enough to make more money if that was all that motivated them. And these are all people who have chosen professions of service in which the rewards are certainly not monetary.

None of us can choose the world we live in – we are presented with the world as it is and we can either accept it or not. But we can choose how we react to what we experience in the world – whether we choose to dwell on the positive or the negative in our dealings with others.

In the last two weeks I have seen far more of the good that people have to offer than of the bad. For a congenital optimist such as myself, in spite of long hours and the toll taken by Hurricane Sandy and yesterday’s winter storm, it’s been a good week.

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What got me thinking, though, was the television coverage – once again we have a major weather event and a slew of experts commenting on the role of anthropogenic global warming on the weather, plus the expectation that storms like this will only become more common as Earth’s temperatures continue to rise. I know that there continue to be avid proponents of both global warming (and humanity’s role in it) as well as those who, for whatever reason, feel otherwise –it is not my intention to take on this debate, but it does raise some interesting questions. In fact, to some extent, there is room for fruitful discussion without even tackling the question of anthropogenic global warming. So here goes….

First of all, while there has been a great deal of discussion as to whether or not the Earth is actually warming. But whether the Earth is warming or not, there is no disagreement over the fact that we have only a finite amount of oil, gas, and coal on the planet. At some point all of these will run out – maybe sooner and maybe later, but eventually they will all be gone, and long before that the cost of finding and extracting them will begin to rise exponentially. Whether we believe in global warming or not – whether we believe that our actions can cause global warming or not – we will at some point need to have an exit strategy from fossil fuels. And if it turns out that our fossil fuel consumption really is driving climate change, so much the better for us for having made the transition!

If we assume that global warming is a real phenomenon then there’s even more to think about. And, I should hasten to add, it doesn’t matter if the warming is caused by greenhouse gas emissions or if it’s simply the expected climatic change of a planet in an interglacial period and orbiting a slightly variable star. If we accept that the Earth is warming then we have to accept that two results of this warming are melting ice (and the concomitant rising sea levels) and that there will be more thermal energy in the atmosphere and oceans to help drive severe storms. It doesn’t matter whether warming trends are driven by human activity or by nature – what matters is that temperatures are rising and what this rise might portend.

So if temperatures are rising then we have only a few options. We can try to find a way to bring the temperatures back down, we can try to find a way to live with them, or we can pursue both paths simultaneously.

Rising sea levels and severe weather both put hundreds of millions of people and a huge number of the world’s major cities at risk. Working on a technological fix for the problem is tempting, but it assumes that we can understand what’s happening, that we can develop a cost-effective (and technologically feasible) way of reining in rising temperatures in  a manner that is itself not harmful to the environment (or to people). And we have to do it before those living near sea level are harmed. I have a lot of faith in our science and technology, but I also know that we can’t produce scientific breakthroughs on a schedule – look at all the effort that’s gone into trying to cure (or prevent) cancer, AIDS, or even the common cold, not to mention energy from nuclear fusion. I’m not sure that I feel comfortable with hundreds of millions of lives depending on our ability to crank out a solution to global warming in a timely manner. The search for an elegant solution to global warming is tempting, and may turn out to be the answer, but do we dare to put all of our eggs into this single basket? Or does it make sense to hedge our bets?

If so, it might also make sense to try to think of how to help stave off the worst that might happen, if only as a sort of insurance policy – a sort of climatic Pascal’s Wager (which I wrote about in another context a few weeks ago). With hundreds of millions of lives and dozens of major cities at risk – and this doesn’t even get into the possibility of droughts in some areas and flooding in others – it seems to behoove us to try to figure out how we’ll respond should sea levels begin to rise and should “100-year” storms become decadal in frequency. I have a mental image of New York City surrounded by walls two hundred meters high, with only the tops of the tallest buildings sticking up high enough to see, just as I have a mental image of Bangladeshis trudging northwards carrying what they can as they try to find a new home. And we can picture the same of London, New Orleans, Singapore, Melbourne, Buenos Aires, Hong Kong, Amsterdam, Tokyo, Montevideo, and any number of other of the world’s great cities. And it’s not only the people – a great deal of our global cultural heritage resides close to sea level as well. We cannot save these people, these cities, or this heritage at a moment’s notice – if the stakes are high enough, as they surely are in this case, then it might behoove us to try to prepare and to adapt in an orderly and well-considered manner rather than trying to slap together a quick fix at the last minute.

So – it doesn’t matter whether or not we think that the world is warming, we need to find a replacement source of energy because we know that a finite supply of fossil fuels will run out at some point. And if the world is warming, it doesn’t matter whether the cause is natural or human activity, we have to try to find a way to reverse the effects or to adapt to a warmer world with (possibly) more violent weather. And we should consider the impact of this week’s storm, and what it might be like if the “storm of the century” turns into a decadal or annual event.

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There’s no need to go into the details – the Cuban Missile Crisis is one of the better-documented geopolitical crises of the Cold War days. The important thing is that, had the crisis devolved into a nuclear exchange, it is quite likely to have been catastrophic – in addition to the radioactive fallout from hundreds to thousands of megatons of nuclear explosions the explosions would have filled the skies with dust and debris; combined with the smoke from hundreds or thousands of massive fires the Earth would have been blanketed in a shroud of almost impenetrable haze that would almost certainly have kicked off a nuclear winter. Between the loss of major centers of population, a great deal of our critical infrastructure, and likely crop failures and mass starvation it is not unreasonable to speculate that a large-scale nuclear war could well have meant the end of 20^th century civilization – it could well have pushed us back, if not to the Stone Age, at least to pre-electrical days.

What impresses me about the Cold War days is that we lived with the possibility of all of this for nearly a half-century – with the near-constant possibility that even a small electronic glitch or military miscalculation could destroy centuries or millennia of progress – and in spite of that not only did we manage to have fairly normal lives, but we restrained ourselves from using our deadliest weaopns. In spite of having tens of thousands of warheads mounted on missiles, bombers, and submarines – all on hair-trigger alert – and in spite of the occasional false alarms (all seasoned with more than a smattering of distrust) we never launched our weapons. Our civilization – and humanity itself– survived and the Cold War ended without a nuclear exchange.

So now let’s fast-forward to the present. We know that we continue to face the threat that a nuclear weapon will be detonated in anger – possibly in an India-Pakistan nuclear war, possibly by North Korea, or maybe by a terrorist organization. And while there is no denying that any such detonation will be horrible, it is unlikely to cause civilization’s end. An attack with one or two nuclear weapons, devastating as it would be, would not threaten all of civilization and would certainly not kick off a nuclear winter. In addition, the fallout from a single nuclear device in the kT range would be far less than that of even a single thermonuclear weapon, let alone hundreds or thousands. Devastating as an act of nuclear terrorism might be for the city (or cities) attacked, it would be a far cry from what we practiced for in my grade-school classes. Thus, ironically, while we might be closer to seeing a nuclear attack today than at any time in several decades, the world might actually be safer today than it was during the Cold War.

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The other topic I wanted to touch on is also related to the use of nuclear weapons – the little-studied impact of mass fires (what used to be called a firestorm). A fascinating 2006 book (Whole World on Fire) by author Lynn Eden details the impact of mass fires that result from nuclear weapons and discusses the fact that American nuclear war planning more or less ignored their effects. While much of the book addresses the organizational reasons for this apparent oversight, what I’d like to take a quick look at is what these mass fires might do.

First of all we need to all be on the same page as to what a mass fire is. The thermal pulse from a nuclear weapon will ignite fires out to several miles from the point of detonation. A multitude of small fires will coalesce into a single mass fire that will consume nearly 100% of the combustible materials within its perimeter. The fire itself will consume so much oxygen that even those who are shielded from the heat will likely die of oxygen deprivation. The rising plume of superheated air draws more air in from the sides – on the one hand this makes a mass fire almost impossible to extinguish as long as there is any remaining fuel; on the other hand the rush of incoming wind helps keep the fire from spreading out laterally once it begins making its own weather. Incidentally, I should also mention that mass fires can be started by conventional means – the Allied fire-bombings of Dresden and Tokyo also initiated mass fires that (in the case of Tokyo) were every bit as deadly as the nuclear bombings in Hiroshima and Nagasaki.

Were a 10 kT nuclear device to be set off the mass fires would engulf everything with a half mile or so of the site of the attack – a square mile or so of terrain. This might not sound like much, but consider how much can be squeezed into a square mile. For example, in New York City this radius would encompass everything from Battery Park to City Hall, pretty much from river to river (Hudson to East River, that is). During the working day there are upwards of a half-million people in this area – more than in all but a handful of entire US cities.

Nuclear response planning today considers the effects of radiation, blast, flash blindness, and even broken glass but it pays scant heed to mass fires. Considering the huge potential impact, it could be that they should also be part of our nuclear emergency response planning.

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Let’s try this with a specific number. According to the only applicable document currently out (Regulatory Guide 1.86), if there is a dirty bomb attack using radioactive cobalt-60, we have to clean up everything contaminated that has more than 10 disintegrations per minute (dpm) for every square centimeter of surface area. What this means is that when we do a contamination survey we have to find there’s less than 10 dpm for every square cm surveyed. With Co-60 this will give a radiation dose of about 1.5 microR/hr and will give an annual radiation dose of less than 15 mrem/yr. This is about the same radiation dose you’d get from a single x-ray and about as much as I got on a round-trip flight to Japan last year. Even if we believe that every single bit of radiation exposure increases our risk slightly, the risk posed by this level of radiation exposure is incredibly small – too low to be calculated with any degree of scientific confidence. This might make sense to apply to a radioactive materials licensee who’s about to sell a building or some surplus equipment, but does it make sense for a chunk of a city contaminated by terrorists? Should our cleanup standards be based on our technological sophistication or on the risk the contamination poses? One problem is that it’s hard to tell someone “Yes – your home has detectable radioactive contamination, but it’s not enough to cause problems so you can move back in.” This is not unlike telling someone “Sure, there are a few anthrax spores in your home, but not enough to worry about.” No matter how scientifically valid, it’s a hard argument to make. On the other hand, trying to clean up to such low levels might be satisfying, but it will also be hideously expensive.

Consider –10 dpm per square cm of Co-60 gives an annual radiation dose of about 15 mrem (more or less), but regulations allow the general public to be exposed to 100 mrem/yr from a radioactive materials licensee. This means, for example, that a licensee has to limit radiation exposure from all sources to that no member of the public receives more than 100 mrem each year – about 7 times the dose from the Co-60 cleanup limits. And other nuclides give even lower doses for the same amount of contamination (Cs-137 is only a quarter as potent as Co-60). Relaxing our cleanup limits so that they are dose-based rather than technology-based will still protect our health because, with radiation exposure, the risk is proportional to the dose to which people are exposed. And, to make a relatively simple assumption (that contamination levels drop off linearly with distance from the scene of an attack) increasing the allowable contamination levels to give an annual dose of 100 mrem/yr (instead of 15) would reduce cleanup costs by a factor of nearly 50. But, again, it’s a hard argument to make.

I’m afraid I don’t have an answer to this question. I know that I’d feel comfortable with elevated levels of contamination in my own apartment, but I also know I’m in the minority (and I have to admit it wouldn’t be my first choice – old habits die hard!). But I don’t expect even the majority of health physicists to be with me on this one just because the idea of keeping radiation exposure As Low As Reasonably Achievable (the acronym for this concept is ALARA) is so deeply ingrained into me and all of my colleagues.

It’s easy to suggest that we develop risk-based cleanup standards (although implementing them is another story). But even when we decide on a cleanup standard, where are we going to put the waste and who will pay for it? On the one point, there are not many radioactive waste disposal facilities in the US. In the aftermath of an RDD attack there will be a relatively small amount of waste that is potentially dangerous and a lot more that will be barely radioactive. It might make sense to let any modern hazardous waste landfill accept the low-activity waste and to only require that the most potent materials be put into radioactive waste landfills – any landfill designed to safely isolate industrial chemicals is certainly able to do the same with radioactive waste, and this step would speed up the cleanup process as well as cutting costs (and at no added risk to the public). But there’s a problem – commercial and hazardous waste landfills aren’t licensed to accept radioactive waste and some states have regulations explicitly prohibiting this. Waiving these requirements might be difficult – especially if the public and elected officials were to oppose such a move. But even if we can solve the problems of where to dispose of the waste, there’s still the problem of paying for the disposal.

Most of the time we make licensees pay for their own cleanup, and this can cost tens of millions of dollars for even a relatively modest facility. But this is for licensees who are trying to close out a facility where they used to do “hot” work – is it appropriate to expect the same of a small business owner (or a property owner) whose property is contaminated from a terrorist attack? Or might it make sense for the national government to pay to clean up after an attack that – regardless of its location – is aimed against our nation? I don’t know – nobody knows – but it’s something we should try to figure out.

So I’m afraid that this week I have some questions but no answers. But the answers are something we need to start thinking about – if we wait until there’s an attack to raise these questions then we’ve waited too long.

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At this point I should state explicitly that I am agnostic on the subject of nuclear weapons testing – I can see good points in favor of testing, just as I can see the attraction of a ban – of saying that there will never again be a nuclear explosion on the face of the Earth (or in its depths). As you read this, please keep this in mind so that, if you feel I am making an argument either for or against nuclear weapons testing, you can attribute this to my writing rather than to my preferences! That being said, on with this posting….

The US never bothered to test the nuclear weapon design that was dropped on Hiroshima – the gun-type uranium weapon was considered so fool-proof that there simply wasn’t a need to waste precious U-235 by running a test. But the implosion design used a few days later over Nagasaki was much more complex – that design was tested before it was used in combat to assure ourselves that it would work as designed and, as we all know, the test worked perfectly. In the early days of nuclear weapons we ran tests for two main reasons – to test new weapon designs and to learn about their effects. The first sort of testing is how we learned whether or not the ever-more advanced designs would work – nuclear weapons testing helped us design miniaturized nuclear weapons that can be packed a dozen to a missile, high-yield tritium-boosted and thermonuclear devices, low-yield tactical weapons, and more. Without this testing we would not have had the confidence to trust our national security to a lump of uranium or plutonium. And at the same time, this testing told the Soviet Union that our nuclear weapons worked – that we could indeed rain destruction on them as promised. Without this testing, for all we (and our foes) knew, our nuclear umbrella might just not hold water.

The other reason for the testing – especially in the early years – was simply to see what these weapons would do. How big was the fireball, and what happened to everything inside? How intense was the pressure wave and how did it affect structures? How much radiation was emitted and how far away was it fatal? How did different types of structures hold up and what did this mean for our population in the event of a nuclear war? There were hundreds of questions that needed answered so that we could build our war plans, as well as our civil defense plans, and the only way to answer them was to set off nuclear weapons to see what happened.

Over time, the reasons for nuclear testing changed. The physics of a nuclear weapon design doesn’t change over a half-century – 20 kg of plutonium acts the same now as it did in 1962, and high explosives compress a sphere of plutonium the same as it did then as well. But even if the physics stayed the same the weapons were changing – what happens (for example) to a plutonium warhead after the plutonium has gone through a few decades of radioactive decay? Will the built-up decay products alter the weapon’s characteristics and, if so, will this affect the way we can use them? What about radiation damage to the components of the weapons – will a few decades of alpha, x-ray, and neutron radiation affect the working of the high explosives or electronics? It’s easy to make a guess, but it’s nice to confirm these guesses with an actual test – one of my professors used to say that a beautiful theory could be ruined by a single ugly observation – no matter how good our mathematical models might be, running an actual test is the ground truth.

Having said that, our weapons scientists have created some fantastically sophisticated software to run on the fastest computers in the world. With this software they can run amazingly detailed simulations to try to understand how our nuclear weapons will behave under a variety of conditions. We can calculate to a high degree of precision what should happen under any of a number of conditions – the question is whether or not we feel comfortable with the results of these calculations. And please note – I am not saying that I trust these calculations implicitly and neither am I saying that I don’t trust them. Truth be told, I don’t know enough to have an informed opinion on the matter so anything I can say on this particular matter is opinion, but not necessarily any better an opinion than yours.

So – say we are trying to develop a new and improved nuclear weapon. We can run sophisticated computer models detailing the behavior of the proposed weapon in minute detail, the characteristics of the explosion unfolding nano-second by nano-second in computer memory. Similarly, we can build detailed models of how a plutonium core behaves with a decade’s worth of decay products built up, or with two decades’ worth for that matter. But even the best of our models contain simplifying assumptions – they are an approximation of reality, but only an approximation. No matter how good our models are, there’s nothing like a real-live test to prove (or disprove) our assertions. This is both the single best reason for – and against – nuclear testing.

Say, for example, there was a flaw in the implosion-type nuclear weapon dropped on Nagasaki and we hadn’t tested the design. Instead of convincing the Japanese that we could bomb them at will – a city per bomb – we’d have simply contaminated their city with plutonium. Not exactly the impact we would have hoped for. And during the Cold War – when our nation’s security was legitimately at stake – it made sense to test our nuclear weapons to assure ourselves (and our foes) that our nuclear deterrent was functional.

But what about today? Do we still need to test our nukes?

Well…maybe not, but it also depends. First, we are no longer in the Cold War and we can’t really pretend that a credible nuclear deterrent is all that stands between us and our enemy’s global domination. Sure – Russia still has enough nuclear weapons to do more than put a dint in our lifestyle, but I remember the fears we had during the Cold War and we are nowhere close to that level today. And outside of Russia there is really no other nation that poses a nuclear threat to our nation’s existence. So the threat we once faced – nuclear annihilation at the hands of an implacable foe – no longer exists. When our existence is at stake then we had better be able to know that we can trust our weapons to work, but do we still have this imperative when our existence is not at stake?

Consider – what would really happen if one of our nuclear warheads isn’t quite able to work as designed? Well – one question to ask is who we expect to use nuclear weapons against and how important it is to prove to ourselves (and to them) that they’ll work as advertised. For the first part – who DO we expect to use our nuclear weapons against? Iran? North Korea? China? Pakistan? Russia? Honestly, I can’t think of too many plausible scenarios that would call for us to actually use a nuclear weapon – like a house with a “Beware of Dog” sign, our nuclear weapons seem intended more as a threat than anything we intend to use. But if we aren’t expecting to actually use our nuclear weapons, do we need to test them, or is the threat that they pose enough? For example – say that the risk of nuclear retaliation is the only thing keeping North Korea from selling a working nuclear weapon to a terrorist group. Would North Korea take the risk that our nuclear weapons don’t work and sell something to an al Qaeda affiliate? Would they risk their nation’s existence on the supposition that our weapons are too old to work properly? Or would they assume that, even without testing, we are still capable of destroying Pyongyang? Any rational nation would almost certainly assume that we know what we’re doing because the downside of a wrong guess would likely be fatal. Even without testing it’s likely that our enemies will assume our weapons work because the consequences of a mistake are simply too dire.

On the other hand, our nuclear weapons are part of our arsenal – whether we expect to use them or not, shouldn’t we make sure we can count on them if we do need to use them? After all, what’s the sense in having something in our arsenal if we’re not sure that it’ll work if we need it? The threat of nuclear retaliation is pretty sobering – but it would be sort of embarrassing if we were to drop a bomb that fizzled. And the longer we go without testing our stockpile, the more uncertainty creeps in as to whether or not they’ll work properly.

At the same time, much of the world has signed on to a treaty banning nuclear weapons testing and there is a general feeling that banning nuclear tests is a good thing. Even if we want to prove that our nuclear deterrent works, do we want to risk international opprobrium by joining North Korea in testing nuclear weapons?

This is one where I don’t have an answer – there are great arguments for and against testing nuclear weapons. I’d hate to argue that we should defy the rest of the world (except for North Korea) and have a test, but I’d also hate to argue that we should just assume – without proof – that an important component of our national defense should be assumed to work without proof. No matter what we do, there’ll be grounds for argument.

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Physicists used to think that the entire universe was deterministic – that if we had enough information about every particle in the universe (position, velocity, mass, etc.) and the fundamental laws governing their motions and interactions then we could predict everything there was to know about the universe for all of time. On the surface this seems to make sense – after all, if we know we have perfect and precise knowledge of every aspect of, say, the balls on a pool table and if we have perfect knowledge of how we strike the cue ball then we should be able to predict exactly where every ball on the table will end up. If we consider all of the particles in the universe – every atom, every electron, every proton, and so forth – and if we know how each of these particles interact with each other then shouldn’t we be able to view the universe as the pool table writ large? Shouldn’t a big enough computer be able to calculate the future and fate of the universe?

Ideally yes – but…there are inevitable uncertainties that complicate matters. The universe is, at the most fundamental level, random, and this randomness creeps in everywhere.

Part of it is that we cannot know everything there is to know about a particle – this is the premise of the Heisenberg Uncertainty Principle. German Nobel laureate Werner Heisenberg realized that the very act of observing a particle changes it and he determined that the more precisely we know, say, a particle’s position the less precisely we can know it’s exact velocity (velocity is the particle’s speed and direction). So the first thing we need in order to have a deterministic universe – exact knowledge of every particle in the universe – is impossible to achieve. The deterministic universe doesn’t even get out of the starting blocks.

But the universe is even more random than that. Consider radioactive decay – my specialty. We can’t look at a single atom and know exactly when it will decay. We can look at a collection of atoms and predict how many will decay in a given amount of time, but the exact fate of any single atom is a mystery to us. And there are more examples – but this ought to suffice.

So what’s this got to do with radiation exposure and cancer? Funny you should ask….

It’s tempting to think of our bodies as the equivalent of the deterministic universe – that if we can have perfect knowledge of every molecule in our bodies and the rules behind how our cells operate then we can predict what will happen when we expose our bodies to potential harm. For example, if we know the precise path of a gamma ray through a body then we should be able to calculate exactly which cells it will pass through, exactly which chromosomes it will hit, exactly what genes will be damaged, and whether or not that damage will turn the cell cancerous. But we can’t do this either because of the fundamental physics mentioned earlier. We might know the precise path of a gamma ray, but we can only predict the probability that it will interact with any molecule (DNA or otherwise) with which it interacts in its passage through the body. Similarly, our bodies respond to DNA damage, but this is also probabilistic. So we can’t predict whether or not any particular gene will be damaged and, if so, we can’t predict with certainty whether or not the damage will be properly repaired. Radiation as a cause for cancer is fundamentally stochastic – random in nature – and we can only determine probabilities.

This was a point made by another Nobelist – physicist Erwin Schrödinger, in his landmark essay What is Life? As early as 1944 Schrödinger pointed out genetic information is transmitted by molecules, that molecules are made of atoms, and that the behavior of atoms is probabilistic. Given this, he pointed out that slight changes in all molecules – including the molecules that carry genetic information (they didn’t know that this was DNA at that time) – are inevitable and he proposed this as a mechanism for evolution. Schroedinger had made an inspired guess and, by so doing, he inspired the scientists who went on to become the first molecular biologists. And – again – he stressed the fundamental randomness of our genetics and our biology.

If we think about it this makes sense. Moving beyond the molecular level humans are tremendously complex and we react differently to just about everything. Expose two of us to the same pathogens and one will get sick while the other doesn’t. Expose one person to the same pathogen on two different days and we’ll see the same result. Some of us are lactose intolerant, some develop lactose intolerance later in life, and some happily chug milk for decades. So given all of this, what can we hope to figure out?

One thing we can do is to constrain the problem. With radiation, for example, I can tell you that the effects of a single x-ray will almost certainly be stochastic – it might (or might not) increase the risk of cancer, but it won’t cause skin burns. At the other extreme, the effects of a very high dose are entirely deterministic – expose a person to 1000 rem in one shot and they will certainly die of radiation sickness. So the response to radiation exposure transitions from purely stochastic to purely deterministic as dose increases from 0 – 1000 rem (but the deterministic part of this is death by radiation sickness, not by cancer).

So what does this all mean for us?

Well, first of all it means that a person with cancer can’t say exactly what caused it. We might calculate that there was a 95% probability that a particular cancer was caused by radiation exposure, but there’s still a 5% chance that the person would have got cancer anyhow from a random genetic flaw. Similarly, we can calculate that the risk of cancer from a low dose of radiation might be only a few percent, but it’s still not zero.

This does not mean that we have to abandon all hope, it just means that there are limits on what we can know. The random changes that Schrödinger speculated about are the same sorts of random changes that can give rise to cancer or to any other genetic disease – we might not be able to know them precisely, but we can at least understand what make them more or less likely to occur. We know that some factors increase the number of mutations – smoking is one – and that some factors (anti-oxidants, for example) help to reduce their likelihood. There’s a chance that, no matter how much we abuse our poor DNA, we’ll escape cancer and will live to a ripe old age – it might be a small chance but it’s still there. And there’s a chance that no matter how careful we are we’ll still get unlucky – this is the whole nature of stochastic effects. But by and large we’re in the same place we were in before – eating and living right might not be a guarantee of a long and healthy life, but it sure doesn’t hurt our odds.

The post Figure the odds appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

So (you might wonder), if a reactor can sustain criticality with only 3% U-235 then why would we even want to go to the extra work to make reactor fuel potent enough to explode? And it’s not only research reactors, by the way, that rely on such highly enriched uranium – the reactors on American nuclear-powered naval vessels are fueled with weapons-grade uranium (although other nations have been moving away from HEU fuel).

There are a few reasons, actually, depending on the use to which the reactor will be put. On a military vessel, for example, the reactor has to be compact enough to fit inside a submarine or ship hull. Since each fissioning uranium atom releases the same amount of energy, cramming more fissioning atoms into the same volume means that the reactor produces more power. If my submarine reactor had used commercial-grade fuel then the reactor would have been far too large (or far too wimpy). So in our case the reason for such high-powered fuel was space considerations.

A side benefit was that our core was longer-lived than would otherwise have been the case. As the U-235 atoms fission they are lost to the core; as they are used up the U-235 enrichment necessarily drops. When it drops too far the reactor becomes less-suited for combat operations for a number of reasons – packing more U-235 into the core means that the reactor will last longer before it needs to be refueled. So running weapons-grade uranium meant that our core lasted over a dozen years before it was replaced – compare this to the typical 18 months or so between refuelings at the typical commercial reactor.

Both of these are good reasons, but neither really applies to a university-based research reactor (or an industrial isotope production reactor). Universities are not as space-conscious as submarines and a reactor that operates only intermittently doesn’t really have the longevity demands of a military plant – so why run on weapons-grade uranium?

The main reason comes down to neutron flux – if each fission produces 2-3 neutrons then packing more fissionable atoms into the same volume means that the number of neutrons in each volume of the core (the neutron density) will be higher than with lower-enriched fuel. And if the purpose of the reactor is to produce, say, radionuclides for medical or for research purposes (cobalt-60 is produced when a stable cobalt-59 atoms captures a neutron) then a higher neutron density means a higher rate of isotope production. A reactor fueled with weapons-grade uranium produces more radionuclides at a faster rate than one with lesser concentrations. This is why we once made civilian reactor fueled with HEU.

In the 1950s and 1960s – before the Non-Proliferation Treaty – the United States and Soviet Union both built research reactors for a number of nations, hoping to win followers during the Cold War, and many of these reactors contained weapons-grade uranium. Today this seems sort of silly – spreading highly enriched uranium around the world – but at the time, in a world that was more or less stabilized by the Cold War and in which fears of terrorism did not include weapons of mass destruction, it sort-of made sense. The problem is that today, with the Cold War over and terrorism (not to mention wanna-be nuclear states) on the rise, we’ve got to address the problem.

There are a few potential snags. One is that reactors fueled with less-enriched uranium have a much lower neutron flux and it simply takes a bit longer to get the same amount of neutron activation than with an HEU-fueled reactor. This is not a show-stopper so much as an inconvenience, but it must be acknowledged. Another is that, for scientists running experiments that require a long-duration irradiation at very high neutron flux, there may be few (if any) viable alternatives. But there are few experiments that really have both of these requirements so this affects few (if any) active research programs.

The other snag is that refueling reactors is neither simple nor cheap. The irradiated fuel is chock full of radioactive fission products and must be handled carefully to avoid any harm to the staff engaged in the work. It also has to be kept shielded and cooled (not to mention secure) during transport, and then it has to be placed into storage or recycled at the end of its journey. Not to mention refueling the reactor with fresh low-enriched uranium if the reactor is still to be used. And that doesn’t even get into the details of modifying the reactor’s operating license, re-training staff, and so forth! There’s not a step in there that’s cheap or easy – but it’s certainly better than the alternative, which is why the US and Russia have been engaged in refueling or defueling this part of their Cold War legacy. As with my sons’ room, cleaning up this particular mess is neither exciting nor easy – but it needs to be done.

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Most of the time I am in favor of less-prescriptive regulatory guidance – as an experienced radiation safety professional I’d rather come up with my own solutions to, say, keeping radiation exposures as low as reasonably achievable (ALARA, the guiding philosophy of radiation safety in most of the world’s nations). But faced with so sudden and so dramatic a change in paradigm – and when faced with a problem that was outside my expertise in radiation safety – I found myself wishing for more guidance from my regulators. Nobody will be injured by swallowing minor amounts of radioactivity – the worst that had happened before 9/11 – but even if the radioactivity from a dirty bomb attack is not dangerous, the explosion and panic can be deadly (not to mention the cost of a cleanup). I’m a health physicist, not an expert in security or counter-terrorism – what I really wanted from my regulators was advice on how to secure my potentially dangerous sources from a threat that was outside all of my experience.

While the regulators didn’t exactly spring into prompt action, the Nuclear Regulatory Commission did issue a series of orders beginning in 2005 that helped clarify measures that could be taken to help safeguard high-risk radioactive materials. These are about to be collected into a single new regulation, 10 CFR 37, that will put much of this information in one place.

As a former Radiation Safety Officer (RSO) I think it’s great to collect all of the disparate NRC orders into a single new regulation, but I find myself wishing the NRC had gone further, keeping in mind that most radiation safety professionals aren’t security experts. For example, the upcoming rule has tons of verbiage devoted to telling licensees how to establish a program to ensure the trustworthiness and reliability of workers granted access to radioactive materials, but it doesn’t provide any guidance on how to actually secure specific radioactive materials (For example, are normal locks OK, or is keycard access needed to control access to a 1 Ci Cs-137 source?).

One of the keystones of these rules is the requirement that people must be deemed “trustworthy and reliable” before they are permitted to have unescorted access to high-activity radioactive sources, and this is one of the parts that I’m not sure I’d feel comfortable with as an RSO. Part of the T&R program is specified in the rules – requiring fingerprinting and a background check. But part of it is left to the judgment of the T&R officer. The T&R officer is required to have a background check and to be fingerprinted, and the NRC verifies their trustworthiness and reliability. But not much more is written – the T&R officer can be the RSO, the head of security, a manager in Human Resources, or virtually anyone else proposed by the licensee. The reason this gives me pause is that, as an RSO I was our organization’s most knowledgeable radiation safety professional, but security is not my game – I know how to select technically competent staff and how to find a technician who will give me a full day’s work, but I’m not trained in how to evaluate a person as a possible saboteur or terrorist. I’d rather have Security handle this task, but under the new regulation there’s no requirement that security evaluations be performed by security professionals.

The NRC will undoubtedly be developing guidance on how to implement the new regulations – there is a draft out (dated 2010) that I hope will be updated and issued to help licensees figure out how to comply with both the letter and the intent of the new regulations. Absent such guidance we are likely to end up with a hodge-podge of approaches to radioactive source security by RSOs who are professional health physicists, physicians or medical technologists, industrial radiographers, and so forth. It would have been helpful for the NRC to have required participation by a security professional – the head of institutional security for large organizations or a security consultant for smaller ones (there are a number of relatively small businesses that possess dangerously high-activity sources).

OK – so what? We’ve got a new law on the way that should help to consolidate a lot of the existing rules and orders on radioactive materials security, and (hopefully) some guidance on how to implement these new laws. It doesn’t seem to do any harm, and by putting so much in one place it can certainly make things easier for the licensee. What’s not to love?

The biggest thing is that this seems to be a rule written by administrators, for administrators. Don’t get me wrong – the administrative stuff is important! It’s nice to know the standards I should meet in order to decide (and demonstrate) that a person should be allowed to have unescorted access to high-activity radioactive sources. It’s also good to force licensees to have a security plan, to know when to notify law enforcement agencies that something has gone wrong, and so forth. But there’s more to security than getting the paperwork right, and that’s where licensees could use some more help – what would be great would be specific practical guidance.

Say I’m applying for a new radioactive materials license and I am to be RSO at a small facility with just enough radioactive materials to fall under this new rule, but we’re not large enough to have its own security force. I know that I need to secure the sources, but what constitutes adequate security? Is a padlock sufficient, or should I have a full-blown safe or vault? Should I put in motion detectors and, if so, what specifications should they meet? What about cameras (and if so, what kind and how many)? Do I need to have an alarm that automatically sounds at the local police precinct? And so forth and so on…. I need more than a bunch of file folders filled with plans and lists – what I need is a list of vendors and model numbers, or at least a list of minimum acceptable specifications for my cameras and locks. In short, I want a radioactive materials security program that will keep secure my sources against theft in addition to meeting paperwork requirements.

All in all, the new rule is a good start – at the least it makes it easier to figure out where all of the requirements are located. But from a practical standpoint it’s no more than a start.  Given the reason for the law – to help prevent a terrorist attack with radiological weapons, let’s hope that more practical assistance is on its way.

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Blaise Pascal (1623-1662) had a struggle with religious faith for much of his life, finally resolving many of his conflicts when he posed religious belief as a problem in logic rather than of faith. Pascal realized that there was an asymmetry in religious belief versus non-belief and this asymmetry made a huge difference. The short version is that Pascal was weighing a lifetime of behavior versus an eternity of reaping the fruits of that behavior. Here are some of the options Pascal saw:

1. There is a God and we live a good life (e.g. denying ourselves the temptations and pleasures to which we might otherwise succumb): A lifetime of self-denial to be rewarded with an eternity in Heaven
2. There is a God and we live a life of dissolution and fun: A lifetime of fun and pleasure “rewarded” with an eternity of torment in Hell
3. There is no God and we live a good life: A lifetime of self-denial with no reward after death.
4. There is no God and we live a life of dissolution and fun: A lifetime of fun and pleasure with no punishment after death.

The way Pascal saw it was that he faced the certainty of a lifetime spent however he chose to spend it – either in fun or in self-denial – while he faced the possibility of an eternity of punishment or reward. So in choosing his behavior he was wagering a mere lifetime of behavior versus a potential eternal payback. Pascal concluded that it made sense to act as though God existed since the worst case (finite pleasure followed by infinite punishment) was so much worse than the alternative (finite pleasure followed by nothing). Or, put another way, if the downside is sufficiently dire then it makes sense to try to avert it, even if the potential upside (in this case an eternity in Heaven) is as hypothetical as the worst case. One way to think about it is that a lifetime of self-denial and discipline is (relatively speaking) fairly cheap and easy to do compared to an eternity of torment. Pascal’s Wager is a form of cost-benefit analysis.

So let’s think about this outside the original scope of Pascal’s thinking.

My homeowner’s insurance is a sort of Pascal’s wager. I can (in theory) choose whether or not to buy insurance – the cost of the insurance is relatively minor compared to the cost of our house and belongings. I might pay insurance for decades and never need to use it, in which case I’m out the cost of the insurance premiums. Or I might choose to go without insurance and if nothing happens then I’ve saved myself a few tens of thousands of dollars. On the other hand, if my house burns down and I’m uninsured then I’m out everything – it makes sense to buy insurance to avoid this option, even if the odds are that I’ll never need to use it.

Much of what we do – especially in the realm of preparing for the worst – is a sort of Pascal’s wager. In each case we’re making a decision to spend a finite amount of resource (money, personnel time, equipment) in order to try to avert a disaster. So, for example, preparing for flooding in New Orleans is a no-brainer – the fact that the city is prone to flooding is far from hypothetical and we know how bad the results can be, both financially and in human terms. So, unless we are prepared to abandon New Orleans and let it return to swampland then it makes sense to take actions to protect the city against a certain flood. Similarly, preparing for earthquakes in California makes sense, as does preparing for wildfires in the American West.

OK – these are easy ones because we know that flooding in New Orleans and earthquakes in California are certain to happen with regularity. But then let’s think about some of the other challenges we face.

The world hasn’t seen a nuclear attack since 1945, the number of the world’s nuclear weapons is decreasing annually, and (so far) we have been able to pretty much control both nuclear weapons and fissile material. On the other hand, we know that not all nuclear powers (or wanna-be nuclear nations) are as trustworthy and reliable as we would like and we know that there are terrorist groups who would want to attack us with nuclear weapons. And we know how devastating a nuclear attack can be – perhaps not infinite and eternal torment, but a pretty close approximation for those affected. No matter how unlikely such an attack might be, it would seem to make sense to take what actions we can to avert such an attack, and to prepare to respond to help to mitigate the aftereffects. The question to ask is how much we should do to avert or prepare.

Pascal’s wager is based on the possibility of an infinite bad side, so virtually any sacrifice can be justified. In addition, Pascal was thinking only of himself as an individual. But when we think about even something as horrific as a nuclear attack we are talking about a finite bad side, and when we think about the cost of averting such an attack or preparing for the aftermath we are talking about costs to society. To take an extreme example (and yes, I know this is unrealistic, but it is illustrative!) – suppose we decide to spend every last dollar in our national budget to try to prevent a nuclear attack against one of our cities, and to put plans into place to deal with the aftermath in the event an attack were to happen nevertheless. We would certainly be better-prepared and likely safer from terrorist attack if we devoted our entire federal budget to this end. But at what cost? We’d have to eliminate federal funding for roads, environmental protection, education, scientific and medical research – all programs that make a difference in the lives of everyone in this country. Social programs would vanish as well – programs that, whether you agree with them or not, make a vital difference to millions of Americans. Grants to states would also cease, with the exception of those related to nuclear preparedness, affecting millions more.

This makes the calculation a lot more difficult. Consider – in both cases (nuclear attack or the possibility of going to Hell) the probability of the threat is unknown. But the stakes for Pascal were his individual torment versus his individual sacrifice while in nuclear defense and preparedness we are talking about a torment that might affect millions and a cost that would affect tens or hundreds of millions. How do we even begin to make this calculation? Obviously we can’t abandon all of the responsibilities of government to concentrate on this one aspect of security, but neither can we do nothing. The question is what DO we do – how much should we invest as an insurance policy against a nuclear attack?

The question becomes even more complex when we consider other, lesser concerns. A dirty bomb attack, for example, is hardly an inconsequential event, but it pales in comparison to a nuclear attack. On the one hand, a dirty bomb attack is thought to be more likely than a nuclear attack; on the other hand, it is also far less damaging. So do we put more resources into trying to avert (or plan for) a dirty bomb because it’s more probable, or do we put less resources into this effort because it’s less likely? I suppose we could try to develop a mathematical formula to try to pin this one down – we could include variables that would include the probability of an attack, the number of lives that could be saved, the probability that our efforts will be successful, the cost (financial and societal) of a successful attack, and so forth.

The problem is that virtually every term would be a guess – in reality we have no idea of the probability that we’ll be attacked by any given weapon – there has never been a radiological attack and there have been no terrorist attacks with nuclear weapons. But we can’t assign a probability for the future based on a past record of no events. Similarly, we can’t really calculate the cost of a successful attack – we have no data points at all for a radiological attack and there are no examples (even in testing) of the effects of a nuclear attack in a city such today’s Los Angeles, New York, London, Mumbai, or any of the other major cities of today. We can guess, but if we claim that whatever numbers we’d put into our equation are anything other than a guess, we’d be deluding ourselves. In these cases, Pascal’s Wager can be no better than semi-quantitative.

Let’s take one quick example – the average US home costs about $250,000 and the average homeowner’s insurance policy is about $500 annually – about 0.2% of the cost of the home and somewhat less than that fraction of the cost of the home plus belongings. But there are a lot of caveats – my insurance is reduced by having smoke detectors, deadbolts, a home alarm system, and so forth. It’s also reduced by the dearth of insurance claims and the low crime rate in our part of town – just as those who lack these factors will pay a higher rate. The insurance companies are out to make money and the only way to do that is to very carefully weigh the premiums they charge against the probability that a loss might exceed the total amount of premiums paid over the life of our insurance policy. They make use of every scrap of information available – including their extensive experience – to make these calculations. Compare this to our trying to determine our society “insurance rate” against a terrorist attack of the sort we’ve been discussing. We can guess at the amount of loss we might see (one estimate is that costs could run into several tens of billions of dollars or more when longer-term economic impacts are tallied).

If we pay the same fraction for RDD “insurance” as I do for my homeowners insurance then we could justify spending, say, $200 million annually to protect against a potential loss of $100 billion. But, having said that, it’s not quite that simple for the reasons I noted above. Not only that, but we also have to ask ourselves what we are guarding against for our $200 million – is this just to guard against a dirty bomb attack, or against any attack that can lead to a $100 billion loss? Do we assess each possible event (and its potential cost) independently and add up the sum of all of these to determine our terrorism “insurance premiums” or do we take credit for measures that might be protective against multiple types of attacks? And how do we assess the likelihood of an attack? Do we assume, as did FBI Assistant Director Majidi in February, 2011 that the risk of a WMD attack is 100%, do we point to the fact that there have been no large-scale WMD attacks since the 1995 sarin attacks in Tokyo (and none at all since the 2001 anthrax attacks), do we look at the number of plots that have been discovered (and the fact that they’ve been thwarted), or do we just give it our best guess? And for that matter, how do we factor in the cost of our military, which combats terrorism as well as defending our nation and safeguarding our allies. Again – the best we can hope for is to be semi-quantitative and to try to justify our assumptions as best we can. But, at the same time, we should be honest as to where we are guessing.

There are some obvious answers to what actions we can justify taking – in any cost-benefit assessment we should take actions that are cheap and easy to accomplish because the resources put into them are trivial compared to even a slight risk from a modest event. Spending tens of millions to prevent an attack that could cost hundreds of billions – even if the probability is low – makes sense. Even spending billions of dollars can be justified if the probability is high enough. The question – again – is not whether or not we spend to protect ourselves, but how much spending can be justified.

To take one final step, we can also look at our own behaviors and actions. It makes sense to take actions that are relatively simple and cheap to protect ourselves from harm. When we buy locks for our doors we are spending a few hundred dollars to protect us, our families, and our belongings from theft or harm, just as when we pay our insurance premiums we’re spending a relatively small sum to protect against the risk of loss. Smoke detectors are cheap, as are seatbelts and vaccinations and so many other actions we routinely take. But how many people are willing to bunker down 24/7 in an armored home to reduce our risks even more? At some point we have to accept some degree of risk in our lives unless we’re planning on divorcing ourselves from the world. Or, put another way, taking maximal precautions to safeguard our lives would mean giving up our lives, just as taking maximal precautions to safeguard our nation would mean giving up on all of the other governmental responsibilities and services. Certainly we should protect ourselves – but with finite resources to spend and all of society to consider we have to be judicious in our expenditures.

The post Pascal’s Wager appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

In a reactor there are three basic sources of radioactive waste – activation products, fission products, and transuranic materials. Activation products come from neutron bombardment of stable atoms – adding a neutron, say, to stable cobalt-59 turns it into radioactive cobalt-60. This can happen with any stable atom in the neutron-rich environment of a reactor core – even the water used to cool the reactor core can capture neutrons to form radioactive tritium, and any air dissolved in the water can become neutron-activated as well. But in a nuclear reactor the majority of activation products come from the metals that make up the reactor itself – cobalt (added to some metals to harden them), iron (in the steel pipes and components), manganese (added to high-strength steels), and more. And when the steel suffers from wear and tear, the corrosion and wear products that flake off from the pipes and other components can collect in low-flow parts of the plant or are filtered out by the water purification system – this is a major source of radioactive waste. Luckily, neutron activation products are usually relatively short-lived and decay away over a period of months or years – at most a few decades. Since the formation of activation products is a function of neutron flux (which all reactors have) and the chemical composition of the reactor components (which all reactors have), we can expect that both conventional and thorium-cycle reactors will produce similar suites of activation products. On the other hand, since the molten salt reactors operate at lower pressures, it might be possible to alter the makeup of the metals that comprise the reactor vessel, pipes, and other components – in a reactor that operates at near-atmospheric pressures. it might be possible to adjust the metallurgy to a mix that produces fewer of the longer-lived nuclides.

Fission products are another form of radioactive waste. Hit an atom of U-235 (or U-233) with a neutron and it’s likely to split into two parts (the fission fragments), both of which will be radioactive atoms. While we can’t predict in advance what fission fragments will result from splitting any individual atoms, there are some patterns that we can see. For example, while fission products can have any atomic mass between about 70 and 166 atomic mass units (1 amu is a little less than the mass of a single proton), most of the fission products cluster around atomic masses in the 130s and the 90s. What’s happening is that the atoms split, but not exactly in half, and some neutrons are given off as well. Anyhow – what this means in practical terms is that every uranium atom that fissions produces two radioactive fission product atoms.

In a conventional uranium reactor the atoms of uranium fuel are sealed within a clad that contains not only the fuel but the fission fragments as well. So under normal circumstances the fission fragments will remain locked away – some will leak out, but not many. On the other hand, if there is a defect in the cladding the fission products can escape into the coolant. Either way the fission products will add to the radioactivity of either the spent fuel (if the clad remains intact) or of the reactor plant itself (if the clad leaks). Luckily, with a very few exceptions, the fission products from both U-235 and U-233 fission are fairly short-lived. In fact, there are only 8 nuclides that are both long-lived and produced in abundance – these include some that are pretty well-known (Cs-137 and Cs-134) as well as some lesser-known nuclides (Tc-99, and Kr-85). These are the nuclides that can make spent reactor fuel dangerously radioactive, and some of these (the cesium nuclides) are among those still hanging around in Japan.

If you have a Chart of the Nuclides handy you can look up the fission product yields for U-233, U-235, and Pu-239 – this will tell you, for example, that fissioning U-235 produces something with a mass of 137 amu about 6.19% of the time while a fission fragment of this mass occurs slightly more frequently (6.76) when U-233 fissions. MOst fission products are short-lived so this 137-amu atom will decay merrily away through short-lived nuclides until it reaches Cs-137, with a half-life of 30 years. So by looking at the long-lived nuclides in any atomic mass along with the frequency with which atoms of this mass are produced we can work out a profile for our radioactive waste.

Interestingly, the fission product curves for both U-233 and U-235 are pretty much the same – both nuclides are so close in mass that they have similar fission product profiles. In addition, the amount fission products produced are solely a function of the amount of energy a reactor produces – splitting a U-233 atom releases about as much energy as does splitting a U-235 atom, so producing a MW-hr of energy requires splitting the same number of atoms in both cases. And since each fission produces two fission fragments, the same power output will produce about the same number (and radioactivity) of fission products from each of these devices. The bottom line is that fission product production should be more or less a wash when we compare thorium-cycle reactors to their conventional cousins. What makes the molten salt reactors interesting (for both activation and fission products) is the ability to continually filter out these radionuclides – even were the amount of radioactivity produced be the same, in a molten salt reactor they can be removed as the reactor operates, making them easier to deal with.

So – both the thorium-cycle and conventional reactors should produce roughly the same activation and fission products. But where the thorium units shine is in the production of transuranic nuclides – those elements that lie beyond uranium on the periodic table. As mentioned in last week’s post, the transuranics are produced when uranium atoms capture multiple neutrons to form plutonium, americium, and even more exotic elements. Lighter atoms are further away from the heavy transuranics, making them more difficult to produce. And since it’s many of the transuranics that hang around for centuries, this also reduces the length of time that the fuel is dangerous. This same characteristic, then, accounts for two favorable characteristics – the relative lack of plutonium produced by these reactors (making them more proliferation-resistant) and the lower burden of radioactive waste they produce.

In Superfuel, the author also discusses the possibility of using thorium-cycle reactors to “process” existing spent fuel and radioactive waste by using the neutron flux to transmute this waste into shorter-lived nuclides. While this is true in principle, this is something that can be done in any nuclear reactor – it’s a function of the waste being exposed to a neutron flux, and every operating reactor has a plethora of neutrons. But I suspect that, in real life, this is no more likely to be accomplished in a thorium-cycle reactor than it is in today’s reactors – it’s something that’s possible, but I’m not sure how likely it is to take place. But this is not a negative; rather, it’s the lack of a positive.

So, let’s sum this up:

• Fission products are largely the same for both reactors
• Activation product production for thorium-cycle reactors might be lower if the less stressful environment (lower pressure) allows the use of alternate materials
• Production of transuranic nuclides is decidedly lower in thorium-cycle reactors.
• But the ability to chemically process molten salt (in a homogeneous liquid-fuel core) makes it possible to scrub radioactivity from the fuel on a continuing basis, reducing the build-up of these nuclides over time.

From this it seems reasonable to conclude that thorium-cycle reactors do offer clear advantages over conventional devices in this area, although these advantages might not be as pronounced as the pro-thorium advocates might suggest.

Finally, let’s try to sum up what we’ve discussed in this series of thorium postings.

Reactor design and construction – we are more familiar with building the “conventional” high-pressure and high-temperature water-cooled reactors, so these have an advantage by virtue of experience and familiarity. However, molten-salt thorium reactors can operate effectively at atmospheric pressure and they don’t require many of the components that make our current fleet of nuclear reactors so complex. Overall, the advantage here goes to thorium-cycle reactors because of their potential simplicity and lower mechanical stress (although to be fair it should be noted that it is possible to build liquid-fuel, molten salt-cooled uranium reactors).

Fuel economy – in a thorium-cycle reactor as much as 100% of the atoms are capable of being transmuted into U-233 and fissioned, compared to less than 1% of the atoms in natural uranium. In addition, there are about four times as many thorium atoms as uranium on Earth. Thus, there are more pounds of thorium than of uranium for us to use and each pound contains more fuel atoms. In this category, thorium has a clear advantage.

Proliferation resistance – thorium-cycle reactors produce far less of the plutonium that can be made into weapons compared to uranium reactors, with their high abundance of U-238. In addition, the presence of high-energy gamma radiation from the U-232 decay series and the ability to “poison” the U-233 by adding U-238 adds further complexity to the process of producing nuclear weapons from this type of reactor. The advantage here is also clearly to thorium.

Radioactive waste – both reactors produce similar fission product profiles. The production of activation products depends on whether or not the lower pressures and potentially simpler reactor design permit the use of alternate materials that are less likely to produce radioactive waste. However, thorium-cycle reactors produce far fewer of the more problematic transuranic nuclides, giving them an advantage in this category as well. In addition, the ability to process liquid fuel on a continuing basis and, thus, to sequester the fission and activation products on a continuing basis adds to this advantage.

My conclusion from all of this is that there is a clear advantage to using thorium-cycle reactors, especially in a world that needs baseline energy production without carbon dioxide emissions. If all that stands in our way is the reluctance of Congress to fund this novel technology (not new tech since it’s been around for more than a half-century) and the reluctance of the existing nuclear utilities to experiment with a new style of reactor then we really need to try to get past the entrenched status quo to try to build some of these things. Maybe we can take notes from the Indians and Chinese as they get their own thorium programs up and running.

The post Thorium reactors and radioactive waste appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

University of New Mexico Center for Nuclear Non-Proliferation Science and Technology (http://www.unm.edu/~cnnst/)

At one point John Kennedy predicted there might be over 20 nuclear powers by the mid-1970s – one of the triumphs of the Non-Proliferation Treaty is the fact that, as of the year 2000, there were fewer than 10 and only North Korea was added to the total since then. But we know that the A Q Khan network was selling nuclear weapons technology to anyone with a checkbook – we’re still not sure exactly who his clients were, but even one would be too many. And we also know that the US developed a nuclear weapon with 1940s-era technology – every nation on Earth now has access to the level of knowledge and technology adequate to design their own nuclear weapons.

Uranium enrichment is one way to produce fissionable materials, but it’s not the only method – plutonium also explodes quite nicely and plutonium production is not very hard to do. In fact, every operating nuclear reactor produces plutonium; a significant fraction of the power produced by our nuclear reactors comes from the fission of plutonium that’s produced in the core during normal operations. This means that, with very few exceptions, every nuclear reactor on Earth produces plutonium and the spent fuel from these reactors contains this plutonium – with some chemical processing this plutonium can in theory be extracted and made into a nuclear weapon. This is one of the downsides of nuclear energy – the spent fuel is not only intensely radioactive, but the plutonium it contains must also be safeguarded. This is one of the trade-offs of nuclear energy – carbon-free baseload power and plutonium. One of the advantages of the thorium fuel cycle is that is it more proliferation-resistant than the more typical uranium cycle – let’s see why.

A quick recap – in a “conventional” nuclear reactor the uranium fuel holds in the neighborhood of 5% fissionable U-235 and the other 95% or so is U-238. In the neutron-rich environment of the reactor core the U-238 atoms capture a neutron to become U-239 and, a few days to weeks later, the U-239 decays to form Pu-239 – the stuff of which bombs can be made. This means that 95% of “conventional” reactor fuel has the potential to become plutonium and the plutonium can be chemically separated from the uranium to be made into weapons. By comparison, a thorium-powered reactor uses neutron capture to turn Th-232 into U-233, which is what fissions. And this is where things get a little interesting.

First, U-233 is about as fissile as Pu-239 – there’s no getting around the fact that a thorium-cycle nuclear reactor produces material that can be made into nuclear weapons. What makes the thorium cycle more proliferation-resistant is that there are some kickers.

One of these is that the thorium cycle not only produces U-233, but also U-232 and over time U-232 decays to stability through a slew of other nuclides. Some of these nuclides emit gamma radiation and one, the thallium-208 gamma – is a whopper with an energy of 2.6 million electron volts (by comparison, visible light photons have energies of several electron volts, x-ray energies are typically in the tens of thousands of eV (keV), and even most gamma rays have energies of in the hundreds of keV). As the U-232 ages, the radiation from its progeny will increase – it can actually become increasingly dangerous to work with as time goes on. Not only that, but these high-energy gammas are hard to hide – they are so penetrating that they’ll punch through standard radiation shielding.

OK – so why not just separate the U-233 a nuclear weapons program would want from the U-232 that they don’t want? The big reason is that U-232 and U-233 are chemically identical (unlike plutonium) so removing the U-232 poses the same challenges as uranium enrichment – in effect, a nation trying to use the thorium cycle to produce nuclear weapons would have to face the technical challenges of both uranium enrichment and running nuclear reactors. It just doesn’t make sense to pursue this route to a nuclear weapon. It’s possible, of course, to chemically remove the decay products that produce the gamma radiation, but it’s just going to keep coming back as long as there’s any U-232 present; with a half-life of nearly 70 years the U-232 is just not going to go away anytime soon. Another easy-to-take step can help to reduce the proliferation threat even further – adding some U-238 to the mix to make it even more difficult to produce something that will go boom. And, again, the fact that U-232, U-233, and U-238 are both chemically identical means that separating the U-238 and U-232 from the U-233 still requires uranium enrichment. The bottom line is that using the thorium cycle to produce the material for nuclear weapons is dangerous and difficult, it’s easy to thwart, and it’s hard to hide the weapons that are produced.

Of course there’s another route from thorium to a nuclear weapon – trying to breed U-235 or Pu-239 by successive neutron capture. The problem here is that a single neutron capture is not necessarily a likely event; the odds that an atom to capture the six neutrons required to turn into Pu-239 is vanishingly small. Of course it’s easier (and more plausible) to capture two neutrons to become U-235 but, again, there’s the same problem with separating U-235 from the rest of the uranium. So this route is also a non-starter.

So let’s put this together with some other things that have been happening. In spite of the concerns raised by the Fukushima accident, many nations are continuing to go forward with their nuclear energy plans, in addition to the reactors being built by Iran and North Korea. To some extent it doesn’t matter whether these nations are friendly or not – conventional nuclear reactors produce plutonium as a byproduct of normal operation. Nations we don’t trust (e.g. Iran and North Korea) can separate the plutonium from their spent fuel (and terrorist groups can try to seize the spent fuel to separate the plutonium). The bottom line is that any reactor fueled with low-enriched uranium poses a potential proliferation risk and that the risk from reactors fueled with U-233 that has been bred from Th-232 is far lower.

Finally, I have to admit that when I first started looking into this particular topic I was somewhat dubious that thorium would live up to the claims of the pro-thorium crowd in this particular area. I should add that I wasn’t necessarily dubious that thorium posed a lower proliferation hazard than uranium, I just wasn’t sure that it would live up to the hype. But as I looked into it – especially as I dug into the likelihood of multiple neutron capture and the gamma radiation emitted by the U-232 decay series nuclides – I realized that thorium-cycle reactors are every bit as proliferation-resistant as claimed. In a world in which we worry about both nuclear weapons detonated in anger and about global warming it seems that thorium-cycle reactors offer a viable approach to addressing both of these concerns.

The post Back to thorium – the thorium cycle and non-proliferation appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Quick note – I haven’t exhausted the topic of thorium, and I am incredibly gratified at the number of comments my last two postings have attracted and the thought that’s gone into them. But I wanted to take a short break from thorium since I know that not everyone is completely enamored of that particular topic! But never fear – next week I’ll get back to thorium with a discussion of the thorium reactors and their impact on proliferation.

To assure someone that something is perfectly safe the British will say that it’s “safe as houses.” The term is thought to date back to the railway bubbles of the late 19^th century – when they burst and sent stocks plummeting people returned to their senses, realizing that while stocks can rise and fall, real estate tended to maintain a slow but steady upward trend. The last few years, though, we’ve found that even real estate isn’t safe as houses. And much more recently it seems that even some of the most dangerous materials in the world might be safe as houses – at least safe as houses in the last few years.

In Oak Ridge Tennessee an 82 year-old nun and two sidekicks (57 and 63, respectively) broke into a high-security area at the Y-12 plant, using the sophisticated technique of cutting through a chain-link fence with bolt cutters. This group of youthful ruffians wandered around for two hours before they were finally run to ground – at a facility that stores weapons-grade uranium. Several time zones away WMD security is also an issue, whether we’re talking about the security of Syria’s chemical weapons stockpiles or of the Pakistani nuclear arsenal.

So…highly dangerous materials ought to be kept secure – that’s sort of an easy conclusion to reach, but there’s more to these stories than just cautionary tales about WMD potentially astray in a dangerous world. For example, we might ask ourselves what level of security is appropriate and who should provide it. Or what steps can we justify taking in order to try to keep ourselves secure – and can we justify infringing on another nation’s sovereignty in order to try to secure these weapons to our satisfaction.

So let’s start by thinking about why we want to secure these materials in the first place. I know it seems fairly obvious – we don’t want the bad guys (our enemies) to get their hands on materials that can be used to attack us or our allies. It would be tragic to be attacked with pilfered WMD no matter where they came from; it would be both tragic and embarrassing to be attacked with a bomb made of nuclear materials stolen from one of our own facilities. Since we know that we are at risk from groups that want to use these weapons against us it seems to make sense to try to control those weapons that might be at risk.

So we have to ask ourselves how well our own nuclear materials are if an octogenarian nun can mastermind a break-in at what is supposed to be a highly secure facility and can evade capture for 2 hours.

Let’s stipulate to the fact that this ought to be unacceptable and not dwell too much on that point (although I’ve got to admit that this sounds more like something I’d expect to see in a comedy movie). But it’s interesting to look a little further and to ask why in the world we would allow a private security firm, no matter how good, to guard materials that, if they go astray, could kill hundreds of thousands or millions of people. I understand that private security firms can be quite good – that they often use highly skilled former soldiers and marines, and that they are well-trained and dedicated. But is this good enough? Shouldn’t we want the most destructive weapons on Earth to be guarded by those who have sworn an oath to defend our nation against all enemies rather than those who are working for a paycheck? Please note – I am not doubting the competence or the dedication of the private security professionals at these facilities – what I am asking is if there might be more to keeping our nuclear materials safe, and that perhaps safeguarding them ought to rely on more than a contract.

Moving overseas, we’ve heard of worries about the security of Pakistan’s nuclear weapons, including speculation that the US might already have plans to move to secure these weapons if it looks as though they’d otherwise fall into the hands of terrorists or militants. More recently there’s been concern about the security of Syria’s chemical weapons, including suggestions that the US (or another nation) should move to secure Syria’s chemical weapons if it looks as though the Assad government is going to crumble. And here we’ve got two quandaries – can we secure these weapons, and should we move to do so? Or maybe there’s another way to ask the question – does the potential risk to the US and our allies from these weapons outstrip the risk to our international reputation from actions we might take to secure them?

After all, securing Pakistani or Syrian nuclear and chemical weapons would require our invading a sovereign nation and placing their most valuable weapons under our control. At the very least such a move would be humiliating to Pakistan or Syria, and if we’ve learned nothing in the last decade of war in Muslim lands we’ve learned that memories are long in these nations and that pride runs deep and is nearly as important as oxygen. If we were to land even a small expeditionary force to secure these weapons we might feel safer for a time, but we could also cause wounds that could last for generations. Not only that, but any such effort carries with it the possibility of further dividing the world community into those who support the actions taken and those opposed – it seems entirely plausible that those in favor would include other nations at risk of terrorist attack (England, France, Spain, Germany) and that those opposed would likely include any number of nations in the Middle East, in addition to upsetting nations who are already prone to think of the West (in general) and the US (specifically) as aggressive nations. To justify such an action we would at least have to make a case that the risk to us of inaction would outstrip the risk to us (reputation, international opprobrium, inflaming anti-American sentiments).

OK, so how do we balance the American lives that might be lost in a hypothetical terrorist attack against the cost to our nation from international outrage and increased anti-American sentiments? Let’s try some hypothetical what-ifs.

What if, for example, we know that the collapse of the Syrian government is certain to lead to the seizure of their chemical weapons by a terrorist group and that this group was certain to use them against the US. In a case like this I suspect that most would agree that we’d be justified in acting to secure weapons that would otherwise be almost certain to cause untold American deaths. But this is an easy case – what about something more challenging? What if we knew that these weapons would be used, but not against us – what if we could prove that they were to be used against one of our allies – Britain, France, Saudi Arabia, or Israel. Could we justify the infringement on Syrian sovereignty to avert an attack against a third nation?

I’m fairly certain that the intended target would approve! But what about the rest of the world – could we convince, say, Iran that we were justified in invading Syria in order to prevent a putative terrorist attack against Saudi Arabia? In a case like this the American public (not to mention the public in the nation that would otherwise have been attacked) would probably approve. But what about the rest of the world? Would other nations support our actions, or would this make things more difficult? And what if our intelligence was wrong?

A variation of this would be knowledge of an attack against a nation that is not an ally – what if, say, we had knowledge that terrorists were planning to use Syria’s chemical weapons against, say, civilians in the Sudan, or in the tri-border region of South America (near the junction of Paraguay, Brazil, and Argentina)? Should we risk American lives and possible international outrage to help avert deaths in a nation that has little or no value to our national interests? Is the risk to our international standing balanced by the risk to lives in a nation that we (sorry to say) just might not care about?

One approach might be to use the utilitarian argument – the most good to the most people. If an invasion to secure Syria’s chemical weapons is estimated to cost, say, 1000 lives  but an attack would cost 100,000 lives then the numbers are in favor of an intervention. The problem is that the utilitarian argument is based only on numbers and doesn’t include moral or ethical issues – this is called the utilitarian fallacy. Would we execute a thousand innocent citizens to avert a war that could cost 10,000 lives? Probably not, because this would be morally wrong. But what about executing a hundred people in cold blood to avoid the death of a million – is this morally acceptable? My guess is that most of us would say no, even though the math says yes. But in reality we are not comparing numbers – we are comparing one morally reprehensible act against another. No matter how it might be justified, there are many who would argue that deliberately taking even a single innocent life cannot be justified, even if it were to prevent a war. Hard as it might be for the scientist in me to accept, many problems come down to more than math.

So – should we invade Syria to keep its chemical weapons from falling into extremist hands? Or should we invade a crumbling Pakistan to secure its nuclear weapons? In all honesty I don’t know. But I do know that there are a lot of factors to consider – more than the numbers of potential dead and more than what our gut instinct might tell us is the thing to do. Whatever our leaders choose to do, I can only hope that they are considering not only the math, but the morality and ethics as well as the impact on our international standing.

The post Safe as houses appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

thorium fluoride melting in a laboratory burner flame

Last week I wrote a little bit about how fertile thorium can be turned into reactor fuel. A discussion of how a thorium reactor might differ from a uranium reactor seems a reasonable follow-up topic.

The reactors I worked with in the Navy were light-water pressurized water reactors. Like virtually every reactor we have on Earth our reactor core was filled with fuel elements – uranium fuel was sealed into a zirconium cladding and these metal fuel elements were arrayed in the reactor vessel in a precise pattern. As the uranium fissions it produces highly radioactive fission products – these are trapped within the metal fuel elements and if the metal melts (as happened at Fukushima) all of this radioactivity is released.

The reactor vessel was filled with light water – normal water (heavy water consists of water in which some of the hydrogen atoms are replaced with a heavier isotope, deuterium).  But it’s not enough to simply sustain a fission reaction, to generate power it’s also necessary to find a way to use the energy produced by that fission. In the case of a reactor plant that means heating water to boiling and using the steam to spin a turbine – since this happens most efficiently at high temperatures it helps to have the coolant as hot as possible. And if we are going to try to heat water to high temperatures then that water will have to be at high pressures to keep it liquid. In turn, this requires building components that are not only able to withstand temperatures of several hundred degrees, but also pressures of up to a few thousand pounds per square inch. And at these extreme pressures even a small flaw can cause problems. Not only that, but water at such high pressures will be forced from the reactor plant at tremendous speeds, eroding the pipe and making the hole larger, as well as emptying the plant all too quickly. Not all water-cooled reactors are pressurized water plants – boiling-water reactors are another “flavor” of light-water reactor – but all water-cooled reactors operate at high pressures and temperatures and all suffer from the stresses and worries that go along with those conditions.

Back in the 1950s an alternate reactor design was tested – one in which the high temperatures didn’t require concomitant high pressures. Not only that, but this reactor also eliminated the need for high-precision fuel elements and many of the problems associated with them. And to top it all off, it ran on thorium. Part of the novelty comes from using molten salt and the rest comes from using homogeneous liquid fuel. With the government’s love of initials it was called an LFTR – liquid fluoride thorium reactor – and here’s how it worked – and how it could work today.

One of the interesting things is that the reactor uses liquid fuel – instead of putting an array of metal fuel elements into a tub of water a liquid fuel reactor has fuel particles suspended in the liquid coolant. When the coolant is circulating through relatively narrow pipes the geometry prevents a fission chain reaction from taking place; the fission chain reaction occurs in the more bulbous reactor vessel, where enough of the liquid can collect to sustain criticality (remember that, in a nuclear reactor, “criticality” simply means that the rate of fissions – the reactor power – is remaining constant over time; ALL reactors are critical when they are operating). Anyhow – returning to the main point, a liquid fuel reactor dispenses with fuel elements, control rods and their associated drive mechanisms, and so forth because reactor criticality is controlled solely by the shape of the pipes and other components through which the fuel passes.

Another advantage of liquid fuels is that they can be continually processed to remove fission products as well as to adjust the amount of uranium or thorium it contains. So rather than fission products building up in fuel rods they can be scrubbed from the fuel as it circulates through the reactor system – doing this can help to reduce radiation levels in the reactor plant and buildings as well. So – in theory – a liquid fuel plant should be radiologically “cleaner” than an ordinary reactor, reducing radiation dose to the workers. Not only that, but any reactor accident would likely release far less radioactivity than did the Chernobyl and Fukushima accidents.

The other novel part of the LFTR is the liquid fluoride – the thorium is in the form of a thorium fluoride salt (“salt” is a general chemical term that refers to a specific category of chemical compounds of which table salt is only one); the salt is heated to its melting temperature of several hundred degrees by the fission reaction and the hot salt circulates through a heat exchanger to boil water, forming the steam to drive turbines. What’s nice about molten salt is that it doesn’t have to be at high pressure to be at a high temperature, so the system is under less stress and leaks are less quickly catastrophic. All of these features – lower pressure, less in-core machinery, simpler emergency cooling systems, and so forth – mean that LFTRs are also likely to be much less expensive to build than our current light-water designs.

Another nice feature comes when you combine both of these factors – the inherent safety of the LFTR design. Consider – energy is only produced when the liquid fuel is in a critical configuration in the reactor vessel, and that heat is given up when the liquid salt is pumped through the heat exchanger to create steam. So what happens if the pumps fail? In a typical water-cooled reactor the coolant stops flowing through the core, the fuel heats up to the melting point, and havoc ensues. In a liquid-fuel reactor the fission reaction continues, the liquid heats up, and it melts a drain plug in the bottom of the reactor vessel – the liquid fuel then drains into a shallow tank where it loses its critical geometry and the reactor shuts down. This should – in theory – prevent the sort of meltdown that destroyed the reactor cores in Fukushima and Three Mile Island and that caused the massive releases of radioactivity last year in Japan. I know that a number of more recent reactors are designed to be “inherently safe” but the LFTR comes closer to this ideal than does any water-cooled reactor if only because the fuel is already molten and, when it loses its critical configuration, the laws of physics dictate that it will shut down.

So with all of these advantages it’s natural to wonder why our reactors are still the “conventional” designs loaded with solid fuel rods and cooled with high-pressure and high-temperature water. Martin (the author of Superfuel) contends that the liquid fuel designs were torpedoed in part by the established water-cooled reactor designs that were being pushed by Hyman Rickover, the architect of the US Navy’s nuclear power program. That, plus the nuclear establishment’s level of comfort with a proven technology (the light-water reactors) might have sealed the fate of the liquid-fuel thorium reactor design, in spite of its advantages. I suspect that the reality is a combination of these factors. Regardless of the reasons why these reactors have not been built in the nuclear nations, it seems likely that thorium will become part of the Indian and Chinese nuclear programs – more on that in a future posting!

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Fast forward to two weeks ago when I saw a book called “Superfuel” in which the author, journalist Richard Martin asks fundamentally the same question I raised, but actually goes into the details. According to Martin, the US dabbled with thorium power in the 1950s before giving up on it in the 1970s. Not only that, but there is a thorium movement of sorts in the US, but even more so in India and China. The International Atomic Energy Agency (IAEA) has written about thorium power, and there are a number of papers about it in the scientific and engineering literature.

I’ve been going through a lot of this literature for the last few weeks, trying to condense it down into a single ScienceWonk posting. What I’ve found is that the pros and cons of thorium power are not as simple as one might be led to believe by those arrayed in favor or against thorium power. On balance it seems that there is a lot in its favor, but the case is not as simple as the pro-thorium advocates might have us believe. In any event, I’ve come to realize that the issues surrounding thorium power are far too much to summarize in a single posting – Martin struggled to address them all in his book – and doing justice to the topic really calls for several postings. So that’s what I’m going to do – in this posting I will briefly discuss the fundamental science and technology without a great deal of editorial commentary and in future postings I’ll try to address some of the advantages and drawbacks of thorium power compared to nuclear and other sources of energy. Since thorium power touches on issues of radioactive waste management, greenhouse gas emissions, proliferation, and more, a series of postings seems justified. So – on with the basic science, and we’ll take on the other issues in coming weeks!

The fundamental idea here is fairly straight-forward – if we put thorium into a neutron-rich environment then some of those neutrons will be captured by thorium atoms, transforming the natural Th-232 into Th-233. With a half-life of a bit over 22 minutes, Th-233 quickly decays to form protactinium (Pa-233, to be precise), and the Pa-233 decays with a half-life of just a tad under four weeks to form U-233, which fissions quite nicely. Or, put another way, load a reactor with Th-232 and within several months you’ll have a reactor full of U-233, which can continue to power the fission reaction. A thorium reactor is a breeder reactor, producing as much or more fuel as it consumes.

One of the nicest things about thorium fuel is that every atom of Th-232 can be turned into U-233 fuel. Not only that, but there is four times as much thorium on Earth as there is uranium. So think about these two facts – and remember that, of uranium, less than 1% is the fissionable U-235. This means that one gram of thorium has more than 100 times as many potentially fissionable atoms as a gram of natural uranium – and does not require a costly enrichment process – and Earth contains 400 times as much potential fuel from the thorium cycle as from uranium.

The way a thorium reactor would work in practice is that the whole process would have to be initiated by a sort of “starter core” fueled with uranium and the uranium core would be surrounded by a thorium blanket. Neutrons from uranium fission would be captured by the thorium blanket, breeding the U-233 that would fuel the reactor from there. If the thorium is in solid pellets it’ll be necessary to do some chemical processing to separate the uranium, but chemical processing is a lot easier than uranium enrichment. But an intriguing idea is to use liquid fuel – dissolve the thorium and the uranium into a liquid salt – and the liquid can simply be run through chemical processing on a recurring basis to not only separate out the uranium, but also to remove the fission products. Liquid fuel has both pluses and minuses – I’ll go over them in a later posting on this topic.

With this as a starter, here’s a little bit of a roadmap to future postings on this topic:

1. Thorium reactors can be designed to be inherently safer than the current crop of water-cooled nuclear reactors
2. The waste from thorium-cycle reactors is shorter-lived than that from U-235-fueled reactors, reducing the problem of radioactive waste disposal
3. Thorium-cycle reactors have some advantages when it comes to proliferation resistance
4. And liquid fuel reactors have some advantages over reactors with solid fuel rods.

There’s more, but we’ll leave it at this for the moment. Stay tuned for more postings!

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What fascinates me is where these cosmic rays come from.  Some, of course, come from the sun; protons and neutrons that fly through space at 400 km/sec and more before encountering our planet.  The protons are most likely to be deflected by our magnetic field before they reach us, and the neutrons are by and large too weak to even reach the surface.  But, as with all radiation shields, some small amount of solar radiation leaks through, and this amount grows larger as I fly higher.

The sun, however, is not very exciting when we get right down to it. It is, by and large, a fairly ordinary star that emits fairly predictable amounts of radiation.  When we look at other stars, and when we examine lunar rocks, we find that, with rare exceptions, our local star is just not likely to have any serious impact at all on sea-level radiation levels.  Those rare exceptions arrive about once every few million years, when solar “superflares” might deliver a radiation dose of as much as 100 rem (300 years’ worth of natural background radiation) in a few hours – enough to cause radiation sickness in any person who might be exposed.  But this happens so rarely that, while each species is likely to experience one of these events, they’re not likely to affect any individual.

Far more interesting are the galactic cosmic rays that are striking our atmosphere (and many air travelers) at any moment.  Most of these are born in the death of massive stars, and are accelerated to extraordinarily high energies by processes that we still don’t fully understand.  “Garden-variety” GCRs are fairly straightforward – they simply carry with them the kinetic energy imparted by the supernova in which they were born.  But the highest-energy cosmic rays (a single atom may have as much kinetic energy as a fast-thrown rock) are formed under conditions that we can only guess at.  Some may even originate outside our galaxy – possibly born before our solar system even existed.  I find it sobering to think that a cosmic ray may have been born in a distant explosion billions of years ago, making its way through the universe as our sun formed, as the earth cooled, and as life arose.  And how ignominious for it to meet its end colliding with the aluminum skin of the airplane in which I am riding, after all that travel!

As I mentioned before, the highest-energy cosmic rays are quite inexplicable, and this is for two reasons.  The first is that physicists are hard-pressed to think of mechanisms that can accelerate particles to such high energies to begin with.  We have measured cosmic rays with energies that are staggeringly high – a single atom carrying nearly as much energy as a pitcher’s fastball.  There’s a tremendous amount of speculation about how one can accelerate a particle to so high an energy, but speculation is easy when we don’t know very much.  One possibility is that some supernovae may emit their energy in jets, rather than spraying it randomly into space, while others have suggested that magnetic fields near black holes, pulsars, or highly magnetized stars (magnetars) may be responsible.  But, frankly, we just don’t know for sure.  And the mystery deepens even more, because it shouldn’t be possible for these cosmic rays to retain such high energies for very long – certainly not for the tens or hundreds of millions (or even billions) of years that they are thought to travel through space.  The reason is that, while in transit, these particles are constantly colliding into microwave-energy photons, the cosmic microwave background that is the echo of the Big Bang in which our universe began its life (as an aside, those of us who still have a TV hooked up to an antenna should know that some of the “snow” on-screen when we tune to unused channels is from these Big-Bang produced photons).  These constant impacts are thought to whittle away at the energy of the cosmic rays, never bringing them to a halt, but also placing a putative upper limit on their speed.  So there is no known way to produce these highest-energy cosmic rays and no known way for them to retain their energy – so there is obviously something we don’t know because we see these “impossible” rays on a regular basis.

I have read that, before the first run of any new, higher-energy particle accelerator, physicists very carefully calculate the possibility that they might accidentally form new and dangerous states of matter, or new and dangerous energy densities.  One of the concerns I have read about (admittedly in a popular-level science magazine) is the concern that the fate of our planet may be at stake.  Each time, of course, the reassuring answer is that there’s nothing to worry about, and so far our planet and our universe have survived quite nicely.  And, with each article that I read, the author happily reassures us that, of course, we don’t have to worry.  Our best accelerators cannot even begin to reach energies comparable to the cosmic rays that are, as I sit and read and sip my wine, ending their long journeys in the airplane.  If, the thinking goes, nature’s own accelerator has not managed to produce an end to the universe (or to local parts of it), how can our meager contraptions hope to do so?

So I am comforted that our quest for a better understanding of the universe will not endanger us.  At the same time, I am simultaneously proud that we are capable of producing devices powerful enough to even raise this question, and sobered by the fact that we are so far from reaching the standard set by dying stars in far-off parts of our galaxy.  And, I feel a somewhat wistful for the cosmic rays that, having traveled so far and so long at such incomprehensible speeds, are destined to end their travels being absorbed by me, my dosimeter, and my fellow passengers.  Surely they deserve a more noble end!

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But even actions aren’t the full measure of a person because there are so many times we have to try to peer inside a person’s heart and their head to really take their measure. I used to work with a man who had killed over 100 times – as a sniper in Vietnam. I’m not sure if he regretted his actions during the war – it’s something he never talked about. But I worked closely with him for years and I am sure that he was a moral man, just as I’m sure he would never have hurt a person just for the hell of it, or just because they caused him problems. He did what we expect all of our frontline troops to do – he killed the enemy – and as long as that was where it ended then we can judge him a good soldier and a good man. So actions matter, but before we can really judge someone we need also to look at the reasons behind their deeds (and just to be clear – some actions are so heinous that they simply cannot be justified). This is one of the reasons why we have so many “flavors” in our legal system – to differentiate between shooting someone in cold blood, in self-defense, in defense of another, accidentally, and so forth. In each case the result is the same, but the underlying motive and rationale is what helps us to distinguish between the hero, the madman, and the murderer.

So let’s think about something a tad more prosaic, but still worth considering – matters of security, privilege, privacy, and secrecy – and see what a difference a person’s intent can make. Or, to put it more directly, let’s think about tax returns, governmental decision-making, and national security.

Let’s start with an easy one – privacy. Privacy is one of our constitutional rights and it’s enshrined into innumerable laws. You can’t open my mail, but you can read a postcard sent to me – which is probably why so few of us write love letters (or “Dear John” letters) on postcards. Similarly, my medical records are private, I have passwords for my e-mail accounts, and I only give my social security number to people (or organizations) I trust. Privacy is a fundamental aspect of our society – there are all things that we do or that we know that we don’t want to have in the public domain.  Perhaps we can say that privacy should be an expectation – up to a point.

That point is hard to define, though. One test might be that the right to privacy starts to erode when a person’s actions start to require explanation or when they begin to have a wider impact on society. If I shoot somebody then I had better be able to explain why – my claims to privacy (at least as related to the shooting) don’t hold water. Society needs to know why I took a shot, if only so that society can figure out what to do with me. If I claim that I was suffering from delusions or a mental breakdown then I need to sacrifice the privacy of my medical records so that society can judge whether I should be treated or punished. Similarly, if I claim I was acting at the behest of someone else then my right to privacy in my e-mail, snail mail, and telephone conversations vanishes. When I take actions that impact society I should expect that society will want to know more about me, including information that I might not want to share.

Of course a person doesn’t have to commit a crime in order to affect society. When I was asked to serve on a committee on depleted uranium I had to agree to a background investigation. And we are all familiar with the amount of scrutiny our politicians undergo, including a huge amount of prying into matters formerly held to be private in their lives (past and present, personal and professional), their medical histories, and their finances. This is expected and (for the most part) appropriate – a person elected to office has the ability to have a profound impact on society, and the higher the office, the more potentially profound that impact. Society has as much right to demand to know about its leaders as it does to know about its criminals – something that should be understood by anyone running for any office.

The right to privacy – the need for privacy – isn’t limited to people; companies and nations have these same needs, and for many of the same reasons. I don’t give out my social security number, for example, because I don’t want people to steal my identity and I don’t tell people the weak points of my home security system so that I can keep my valuables secured. Similarly, it’s reasonable for nations to hold closely information that might put them at risk – this is one reason, for example, that we insist on security clearances for so many in the military, in the defense industry, and in government. Whether it’s how to make weapons of mass destruction, the exact combat capabilities of our most advanced planes and warships, or the deliberations deep inside our government there are some bits of information that simply must be kept out of general circulation.

The problem is that it is so easy to justify keeping something out of the public eye – whether it’s personal information, governmental information, or state secrets – and it is so very difficult to always understand the intention of those who are locking away this information. How do we – society – know when the need for privacy is legitimate and when it is not? How can we know what is in the hearts and in the heads of those who are trying to maintain this privacy? And when does the desire for privacy cross the line into secrecy – and when does the desire for secrecy become pathological?

Some cases are pretty straight-forward. Richard Nixon invoked executive privilege to try to hide his crimes so that he could avoid personal and professional embarrassment and so that he could stay in power. Bill Clinton tried to keep his indiscretions secret as well, also to avoid embarrassment and censure. What they did was wrong and their desire to hide it is natural – nobody wants to get in trouble or to be embarrassed.

Of course we’ve seen this same thing come up very recently, and it’s probably best to say that the jury is still out (metaphorically) on the matter. Mitt Romney’s tax returns, for example – is he insisting on a reasonable privacy in his personal financial affairs, or is he being secretive about a potentially embarrassing matter to try to win the presidency? And, in either case, does it matter for a person who’s trying to become the most powerful man in the world – does society have a right to this information from its hopeful future leader? I honestly don’t know if Romney is being private or secretive and I honestly don’t care what his tax returns say (as long as he’s not broken any laws). But a lot of the public (and the media) do care, which is why it’s such a big issue.

And of course we see the same thing in the current administration as well (to be non-partisan about the matter!) – with the White House’s invoking Executive Privilege in the Fast and Furious scandal (for those who have been living in a cave recently, this is the federal program that sold guns they suspected would end up in the hands of Mexican drug gangs in order to see if the guns would end up in the hands of Mexican drug gangs). Is the administration invoking executive privilege in order to encourage free and open discussions within government (which is recognized as being vitally important), or is it to avoid embarrassing revelations of ineptitude in an election year?

Note that in both of these cases the outcome is identical – information is being withheld from society – but the motives in each case make all the difference in how we view the incidents and those involved in them. A principled stand is admirable; a craven desire to avoid embarrassment is not.

Whether we’re talking about state secrets, military secrets, or personal secrets the easiest thing in the world is to simply clam up and refuse to release any information – the underlying assumption being “what they don’t know can’t hurt me.” But this is the logic I learned from my classmates in the third grade – I’d like to think that our government and our leaders have advanced to a more sophisticated and nuanced view of information.

I would suggest a test that can be applied every time someone invokes privacy, secrecy, or privilege – to ask them what would really happen if the information they are husbanding were to become known and how many would be affected by its release. The higher the stakes, the more important it is to keep a secret. Giving away the plans for miniaturized nuclear weapons can potentially affect tens or hundreds of millions of lives – it seems a good idea to keep those plans locked away. Giving away Romney’s tax secrets is somewhat less portentous – society might have a legitimate interest in knowing more about the man who wants to be our next leader, but not many people would be harmed no matter what they were to reveal. Governmental discussions fall somewhere in between – although I’d suggest that we might be better served trying to learn from our mistakes (including mistaken decision-making processes) than trying to hide them away. And when it gets down to the really mundane – my social security number for example, or where I hide the spare key to my apartment – I’m pretty sure that I’m not important enough to society for these bits of information to matter, so perhaps I can be allowed to retain this modicum of privacy.

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A kiloton is an abstract concept. Let’s face it – most of us have no direct understanding of what a kilogram of TNT can accomplish, let alone a million times that amount. A kiloton is just a number – like the national debt – that we know intellectually to be huge, but without a visceral context in which to place it. My submarine could carry nuclear weapons – not the city-annihilating strategic weapons, but the somewhat more diminutive tactical nukes (and many of us speculated on the yield such a weapon might have) but who can look at a metal cylinder a few feet long and a foot or so in diameter and visualize Hiroshima? What made nuclear weapons real to me was not the innocent-looking metal in the torpedo room. What made them real to me was my first visit to the Atomic Bomb Museum in Hiroshima in Y2K – over a decade after I left the Navy.

Even getting off the train in Hiroshima was more of an intellectual exercise than it was an emotional one. I looked around and the first thought in my mind was “This was all gone.” But the city itself looks pretty much like any other Japanese city – big and bustling and a lot of signs I couldn’t read. But when I stepped inside the museum; when I saw not only the photos, but the remnants of concrete and asphalt and brick with the shadows of victims burned into them; when I saw the iron that had melted, the glass that had flowed, and the evidence of lives that had been shattered – this was when the atomic bomb became a more visceral reality for me and when I understood in my heart not what nuclear weapons can do but what an atomic bomb had done.

Although many of the Manhattan Project scientists had an inkling that nuclear weapons were more than just really big bombs it seems fairly likely that the political and military leaders who chose to develop and to drop them took the more simplistic view. It wasn’t until reports began coming back from Occupied Japan that the full impact of what these new weapons could do began to sink in. And over the next few decades of testing – atmospheric and underground – we developed an ever-more sophisticated understanding of what would transpire should out nuclear weapons ever be used again in anger. Calculations and modeling of blast and thermal effects as well as fallout patterns – and the effects of fallout on the population beneath – helped to solidify this understanding by showing how many people could die in a nuclear war. But I suspect that the visual images of houses blasted apart by nuclear tests, the film footage of an entire (mock) forest swaying from the blast wave, and the photos of those civilians caught by fallout – I suspect that these are what made the potential impact of a nuclear attack seem real to our leaders and to those in the other nuclear powers. It sounds incredibly trite to put it this way, but nuclear weapons are far more than an easy way to make a bigger explosion.

This is one of the reasons – in my humble opinion – that Eisenhower’s suggestion that the world develop peaceful uses for nuclear explosions (the Plowshares program), as well as the Soviet and other programs on peaceful nuclear explosions that I discussed in an earlier posting, was fated to fail. Even leaving out the emotional impact of using nuclear weapons in a world that was becoming increasingly fearful of them, nuclear explosives (peaceful or military) produce a LOT of radioactivity and this limits where and how they can be used. And this – from the strictly rational standpoint – is the fundamental difference between any nuclear explosion and a chemical one.

First, think about non-nuclear explosive. Any explosive compound that can blow apart an enemy army or factory can also be used to blow apart a stubborn rock or to blast a tunnel through a mountain. But when the dust has settled (literally as well as figuratively) the work left is simply to scoop up the rubble and haul it away. But do the same thing with a nuke and you also have to figure out how to handle the radioactivity. And if the explosion breaches to the atmosphere then you also have to deal with the fallout and all the problems that can cause. From a purely scientific standpoint this is the fundamental drawback to nuclear explosives – they produce all that pesky radioactivity.

But in addition to the purely left-brain reason that we can’t treat nuclear explosives as just a way to make a bigger boom there are some right-brain reasons as well, and they get back to the first part of this posting. Nuclear explosives are forever linked with nuclear weapons – with Hiroshima and Nagasaki, with nuclear winter and the crew of the Lucky Dragon (a fishing boat caught by the fallout from America’s first thermonuclear test), and with our Cold War fears of nuclear extinction. Setting off a nuclear explosion for any reason at all – peaceful or military – is fraught with emotion and symbolism. Even without the radioactivity it is simply not possible to have a nuclear explosion devoid of social and political impact.

The Plowshares program was a laudable attempt at finding a way to turn nuclear explosives into more than weapons of mass destruction. But it ran into snags that its promoters – such as President Eisenhower – failed to envision. And it is a good object lesson as well – the dangers of nuclear weapons extend beyond the battlefield and go beyond our calculations into the realm of politics and emotion. And as long as they carry this baggage – radiological as well as psychological and political – it is likely best that they not be used.

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When you think about it this shouldn’t be surprising. We had – in one relatively confined space – high-temperature steam, high-temperature equipment (some of it turning at thousands of RPM), scads of high-voltage and high-amperage electrical equipment, and miles of electrical wiring. All of these potential ignition sources were in fairly intimate proximity with all sorts of flammable materials – lubricating oil, fuel oil, weapons, pyrotechnics (flares, for example), and so forth. And, of course, the paper that we had to bring along with us – God forbid a warship should go to sea without several tons of paperwork, and all of it was flammable. So – high temperatures, high-energy electrical systems, and flammable materials in close proximity – of course we had fires, and I’d have been surprised if we didn’t! But – again – there was not a single one of them that ever placed the boat at risk. In fact, the typical “fire” that we responded to was most likely to consist of an acrid smell and possibly light smoke around an electrical panel – no flames per se, but enough to warrant going through the whole fire routine, including shifting the electrical power plant around, opening circuit breakers, breaking out the fire extinguishers, and (of course) reporting it to Naval Reactors.

So, given all of this, imagine my reaction at reading about the furor that has erupted in the United Kingdom with a recent report of a number of fires aboard British ballistic missile submarines (what we called “boomers”) over the last several years – 74 fires on boomers and 266 on all submarines over the last quarter-century. British politicians are calling for investigations while Scottish politicians are using this report as a pretext for pushing to have the boomers moved to non-Scottish ports – even when the report itself plainly notes that the fires aboard the British boats are not much different than those on mine – a lot of incidents of light smoke or an acrid smell, a very few incidents of actual flames, and not a single case in which nuclear reactors or weapons were put at risk. In fact, the report itself notes that 243 of these fires were small-scale, leaving about 1 larger fire per year across the entire British submarine fleet.

Part of what’s happening, of course, is that the Brits – like us – report everything that happens that’s even a little bit untoward. So light smoke and an acrid smell – something that I get from my toaster every so often – gets reported as a fire. In a sense, the British submarine force is being victimized by its very attention to quality – by tracking everything that’s even the slightest bit out of the ordinary the Brits get a great feel for conditions in their submarine fleet and how they can be improved, but they leave themselves open for criticism when these reports are perused by those who don’t understand what they say – or who deliberately mis-represent them.

And this latter part is possibly even more relevant – as near as I can tell there are only two possible explanations for the political furor these reports have engendered. One possibility is that the politicians and others reading the reports simply haven’t read them carefully and just don’t understand what is significant and what is not. The other possibility is that those raising a stink know exactly what is happening and they are deliberately misleading the public to make political points. I’m not sure if I prefer ignorance or dishonesty in a politician – both have their drawbacks – but I don’t see any other likely possibilities. And I know I shouldn’t be surprised at the politicians – these traits are both part and parcel of the political process – but I certainly hope that, in a nation with so long and proud a naval history, there are some of the public who can see through the political posturing and who realize that submarines are still among the safest of the world’s warships.

Finally, although I’d like to think that it goes without saying, I should probably say it anyhow – there is no way to pretend that a fire on a submarine is a good thing or that it is even something to be blasé about! Any fire at sea – even a little bitty electrical fire – has got to be treated seriously. That’s why we sounded the alarm, why we sent damage control teams to respond, and why we reported even the slightest thing to Naval Reactors. We knew that the vast majority of fires we were going to face would likely come to nothing – but we also knew that there would be no warning before something major struck. We treated every fire seriously because we had to assume it could threaten our lives until we could prove otherwise. It’s easy to be blasé today about all of the little fires we had on my submarine – but that’s only because I know today that they were minor. At the time, every puff of smoke got my heart racing, and I’m willing to bet that my shipmates felt the same way.

The conclusions that I draw from this are that British submarines are pretty much like American boats, that both nations’ naval nuclear propulsion programs are among the safest in the world (the US has lost only 2 nuclear subs and the Brits none that I know of), and that politicians in both nations are remarkably resistant to facts when a report comes out that serves their political purposes.

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New neutron detector might be on its way

Sandia National Laboratories recently announced that its scientists have developed a fundamentally new type of neutron detector – using materials known as metal-organic frameworks and a technique called spectral shape discrimination (SSD) to differentiate between neutrons and gamma rays. Neutrons, of course, are given off by nuclear weapons and neutron detection is (dare I say) critical to efforts to identify nuclear weapons that are being smuggled in preparation for an attack.

Current technology relies heavily on a form of helium with 2 protons and a single neutron, called helium-3. Due to a global shortage of He-3 there is now a fairly long waiting period for new neutron detectors – and this shortage has also hit some forms of physics pretty hard as well. A new type of neutron detector that can cut our reliance on He-3 should be welcomed by both counter-terrorism folks and physicists alike. And in the “but wait – there’s more” category, the SSD-type detector is likely to be even more effective at detecting neutrons than the current technology. All in all, very good news – let’s hope that Sandia can find a partner to finish development and bring these detectors to market soon.

More contaminated stainless steel

Here’s another story that includes the line “but wait – there’s more” but in this case the “more” is neither encouraging nor surprising. Another batch of metal contaminated with Co-60 has cropped up – this time in the form of pet bowls rather than tissue box holders. But please read on before deciding to feed Fido or Fluffy from the good china! The radiation dose rates in the bowls found to date are vanishingly low – a fraction of what was found in the tissue boxes and only about twice as high as natural background radiation. And with the contamination fixed in the metal it’s highly unlikely to contaminate either your home or the pet food. We can measure it, but that doesn’t make it dangerous.

This may well be another batch of metal products from the same batch of steel (or possibly residual contamination from the same smelter) that contaminated the tissue boxes in January. If so it would hardly be a surprise – remember that steel is made in batches of 50-350 tons and only a tiny fraction of that amount has thus far come to light. It could be that the Indians have tracked it all down, but it could also be that we’ll be seeing mildly contaminated steel for years to come. But we can take heart that – to date – there’s been nothing that’s more than a nuisance, and that nobody can be harmed by what we’ve seen. And – the silver lining – it should be heartening that we are picking these items up! If we are finding objects that have elevated radiation levels but that pose no health risk then it speaks well for our ability to pick up anything genuinely hazardous. Don’t get me wrong – I’d rather have NO contamination in consumer products. But at least our detection systems seem to be passing these informal tests.

Another polonium murder?

Finally (for this week) one more snippet – news stories suggesting that Palestinian leader Yasser Arafat might have been poisoned with polonium in 2004, two years before the Russian Alexander Litvenenko met the same fate. If true this could open a whole can of worms as people try to figure out who did what – but that’s beyond the scope of my expertise. Instead, let’s take a quick look at what might have been found and how plausible the story is.

A number of media stories have picked this up but they are woefully scant with the scientific facts. What I’ve been able to glean is that – for reasons not made clear – a Swiss physician tested some of Arafat’s clothing for radioactivity and found traces of Po-210 in the underwear and some other clothing. One story goes on to state that radioactivity in the amount of several mBq (milli-Becquerels) was found in one article of clothing and stated that this equated to a multiply-lethal dose of radiation.

First – there is no doubt that polonium can kill. The world saw this in 2006 with Litvenenko and anybody else given the same dose of polonium would have suffered the same fate. So we can check that box “yes.”

Second – it is remotely possible that sufficient polonium would have remained in Arafat’s clothing to be detected today. But it is a remote possibility due to the short half-life (about 138 days) of Po-210. Consider – every half-life sees the amount of radioactivity drop by a factor of two. If we round off to make the math easy this means that on New Year’s Eve of 2012 the amount of Po-210 is reduced to an eighth of what it was the previous New Year’s Eve. After two years we’re down to an eighth of an eighth – less than 2% of what we started with. After 8 years the amount of radioactivity in Arafat’s clothing would be less than a ten-millionth of what there was at the time he died. So to discover, say, 20 mBq today means that there would have been 200 kBq (about 6 microCuries) at the time he died – this is on the order of what is sometimes administered to nuclear medicine patients for diagnostic testing and far more than what Litvenenko was dosed with. So for there to be easily detectable Po-210 in any of Arafat’s effects today means that he had to have been given a whopping dose of polonium at the time of his death – and that this had to have gone undetected until today.

Arafat’s symptoms at the time of his death are equivocal – some could be consistent with radiation sickness but others not so much. But in particular, Litvenenko lost every hair on his body by the time he died – polonium is attracted to hair follicles. But this fate did not seem to befall Arafat, casting some doubt on this hypothesis.

The bottom line is that it’s going to be hard – even with an exhumation and examination of Arafat’s body – to conclusively identify polonium poisoning as a cause of death. In large part this is because the inexorable physics of radioactive decay, coupled with the time lag, works against us. But whatever is determined, we can bet the determination will be controversial. So stay tuned!

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Here are links to each post:

How You Can Help If you agree that society’s complacency concerning nuclear may be unwarranted, please sign our petition asking Congress to authorize a National Academies’ study of that risk, and encourage friends to do the same. My paper, “How Risky is Nuclear Optimism,” provides a brief, but more complete summary of the reasons such a study is needed.

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“How can your government allow this?” she demanded. “How can you just let a hospital ship a high-activity radioactive source to another nation without first checking to see if the clinic is even real, or is even allowed to have radioactivity?”

My reply was that (at that time) any licensee could legally ship radioactive materials to any other licensee as long as the receiving licensee provided a copy of their radioactive materials license to the shipper, showing that the receiving licensee was authorized to possess that amount of radioactive materials. In other words – at that time – I could ship a dangerously radioactive source to anyone in the world based only on their faxing me a copy of their license, with no requirement to ask for verification of authenticity from the regulators. The potential for abuse should be obvious, and luckily our regulators have put much stricter controls in place in recent years. At the time, however, all I could tell my Filipino colleague was that the American hospital had acted legally, if not entirely intelligently.

The reason for mentioning this is that the United Nations issued a press release recently noting that the international body is creating eight “Centres of Excellence” around the world to “help countries mitigate the risks related to chemical, biological, radiological and nuclear (CBRN) material, notably by promoting coherent national and regional policies that allowed them to better share information and best practices.”

This is a great idea – developing internationally recognized “best practices” and encouraging their adoption by as many nations as possible is a great way to reduce the risk that a terrorist group might take advantage of mismatched regulations to assemble the materials they might need to launch a devastating chemical, biological, radiological, or nuclear attack. Yet at the same time, I find myself hoping that these centers will go beyond the scope that is currently envisioned and that they can live up to their potential for doing good.

Let’s take one example – from the field I know best. There are currently internationally accepted standards for radiation safety that have been implemented world-wide – the International Atomic Energy Agency’s Basic Safety Standards (BSS) for radiation. I think it’s safe to assume that virtually every nation on Earth either uses these as the basis for their radiation regulations or is at least aware of them – this series of documents (there are more than the one linked to above, but that one is the most fundamental) covers much of what is considered to be “best practices” for the safe use of radiation and radioactivity. In the case of radiation safety, and trying to avoid a radiological attack, there may be little or no need to make others aware of these standards, but there is a great need to help many nations understand their importance and how to comply with them. In fact, you can make a very convincing case that the written regulations are only the first step in having a good radiation safety program, and trying to get everyone in the world to accept the IAEA standards is only a good first step. But the crux of the matter is in how to apply the standards – whether they are going to be useful or if they turn out to be just another set of documents and rules on the shelf.

Take ALARA for example. ALARA is the fundamental philosophy of radiation safety around the world – to keep radiation exposure to anyone As Low As Reasonably Achievable. This is a great goal, but what does it mean? More importantly, how do I know what I should consider to be “reasonable?” Does it make sense to have everyone wear latex gloves when working with radionuclides? Probably (except for those with latex allergies), because latex gloves – in much of the world – are plentiful and cheap. But what about those nations where gloves are hard to find – is it better to work barehanded (risking skin contamination) or to re-use gloves (risking the accumulation of radioactivity and the spread of contamination around a lab)? And in wealthy nations does ALARA mean wearing a whole-body “moon suit” with forced air? What I’m getting at is that teaching the rules is easy – helping people to understand how to interpret and to use the rules is more difficult and I sincerely hope that the Centres of Excellence will be sending people to spend time on the ground helping their colleagues to learn not only the accepted standards are, but how to use them thoughtfully, skillfully, and sensibly.

I hope, too, that these centers will be a place where information can be shared between participating nations and agencies – where participants can share their problems and the solutions they devised, where they can share procedure and policy manuals, where they can post checklists and flowcharts; in short, where participants can share with each other all of the minutiae that goes into building and sustaining a high-quality program in whatever field they are working in. This sort of “nuts and bolts” stuff might not be very exciting, but it is the practical heart of any good on-the-ground program. Telling a person to conduct, say, radioactive materials security inspections quarterly is a good start – sharing your inspection checklist with him and including pointers on common problems (hopefully during an in-person training visit!) helps to turn that printed requirement into an inspection that actually adds materially to radioactive source security.

Finally, I would add that this sort of work – the international sharing of this level of information – cannot help but to make all of the participating nations safer on a daily basis. Helping to better secure radioactive sources, for example, could have saved at least one life in India in 2010 and would have eliminated the whole radioactive tissue box fiasco earlier this year. The intent of these centers is to help reduce the massive impact of an attack using WMD and that is a laudable goal – but the “collateral benefit” from these centers is potentially substantial enough to justify their existence even in the absence of anything else.

I am encouraged by the United Nations’ decision to stand up these centers – if their charter is sufficiently broad I think that they can do a world of good in helping to prevent needless risk on a daily basis as well as by helping to prevent a terrible attack. I sincerely hope that they will be able to live up to their potential by becoming not just centers from which to promulgate regulations and rules, but that they will also become clearinghouses of practical information, personal mentoring, and hands-on training.

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So let’s think about this a bit – put yourself in the position of a person walking down the street and realizing that the person in front of you is armed and seems to be watching you. What do you do? The military answer is that capability implies intent – to assume that anyone with a weapon intends to use it, and to prepare for a fight if necessary. The civilian world is somewhat different, but I tend to be a bit pessimistic in that I assume that anyone who went to the trouble of arming themselves on their way out the door is probably willing to use their weapons under the right circumstances. So in the case of encountering an armed stranger on the street I suspect most of us would start looking around for a weapon of our own or, if we were armed, we’d draw our own weapon. And now – possibly through nobody’s fault – we’ve got two armed people pointing weapons at each other…and now what?

So can you assume it’s all a mistake, laugh, and put your weapons away? Probably not – not unless you are willing to bet your life on the trustworthiness of an armed stranger who is pointing a gun at you. And the other person has no more reason to trust you – it’s hard to picture a circumstance in which someone holding a weapon on me could persuade me to put my own gun down and just go about my business without some way to assure my safety. It could be that the best option (short of the police showing up and disarming both of us) would be to just slowly back away from each other until we’re out of range and then go back to our day.

Obviously we can push this story further – we can introduce third parties who are also armed, we can look at the quality of weapons (your AK-47, for example, probably beats my pistol), and we can even include socio-economic issues; all of which are relevant to urban or suburban warfare. But let’s think of this in terms of nuclear weapons because a lot of the issues are the same. What do you do when someone’s pointing a (metaphorical) gun to your head, and how do you get to the point of putting your guns away?

The whole thing started in the caveman days (non-nuclear, of course). Caveman Og had a club, which was great when confronted by caveman Erg and his club. But once Erg invented an axe he had an advantage so Og needed an axe of his own. Then maybe Og and Erg moved on to spears and arrows, knives and swords, guns and cannons, and then onto nuclear and thermonuclear weapons – the latest incarnation of the problem. If you are armed and if I’m within range of your weapons then I had better be armed as well, unless I really, really trust you and your intentions. So when the United States developed nuclear weapons, of course the Soviet Union had to do the same. And when the United States developed thermonuclear weapons the Soviet Union had to follow as well – just as we had to follow suit when Soviet missile technology seemed to overtake ours. Britain and France got into the game because the Soviets had a nuclear gun pointed at their heads, and China joined the club because they had no reason to trust the Soviets either. So for a half-century we lived in a society in which a small group of nations were pointing guns at each other – nobody really happy with the situation, but neither was anyone really willing to be the first to drop their weapon. And who can blame them?

The Non-Proliferation Treaty is a good step, but boy does it call for some delicate work! Let’s say you and I each have a gun in each hand. It might be easy enough to agree to simultaneously lower to the ground the gun in our left hands so now we’re only holding one gun each. But we’ve seen this one in the movies – both gunfighters start to lower their weapons and then one suddenly whips his gun up and blows away the other one. If it was the sheriff we applaud his speed (and we never trusted the bad guy anyhow); if it was the bad guy then we condemn his perfidy and hope he is properly shot later in the movie. But with nuclear weapons the stakes are different – what happens if we lower our guard and the other side goes for the quick draw? When the gun’s pointed at an entire nation and hundreds of millions of people I would suggest the stakes are somewhat higher than in a movie shootout. I might decide to risk my life on a quick draw (or on my trust that you’ll be honorable) – but I’m not likely to bet the lives of my wife, children, parents, extended family, friends, and so forth. How could anyone make a bet like that – to disarm completely and unilaterally – knowing that a mistake could lead to the end of your nation?

I don’t think that anybody today expects a nuclear war between the US, Russia, China, Britain, and/or France. But each of these nations continues to maintain its nuclear stockpiles – and the means to deliver their weapons – and there is no sign that this is going to end anytime soon. So we’ve reduced our nuclear stockpiles by an amazing amount – but we still have more than enough weapons to destroy the others many times over. As long as I am holding a single gun with a single bullet you’d be foolish to holster your weapon, turn, and walk away, no matter how much you might trust me.

Over the decades the US and USSR (and later China) might not have fully trusted each other enough to disarm, but they at least grew to understand that the others were really unlikely to pull the trigger. So we developed a sort of uneasy equilibrium based on our mutual experience and on the certainty that nobody really wanted to face an annihilating retaliatory response.

Maybe we can liken the Cold War situation to a couple of soldiers facing each other, neither wanting to pull the trigger and neither willing to turn and walk away – tense but professional, and with the sort of uneasy equilibrium discussed above. Now, what happens when we add an assortment of meth-addled gangsters and neighborhood watch captains? Well…at the least the equilibrium is going to be upset, and it’s probably safe to assume that tensions – and the number of weapons – will stop going down.

So will we ever get to zero nuclear weapons? In all honesty I have absolutely no idea. Given the enormous national prestige that comes from having them, as well as the terrible risk from NOT having them when faced with nuclear-armed opponents I’ve got to say that I’m not expecting to see a nuclear-free world in my lifetime. After all, I’m not going to eject the last bullet from my gun, leaving you with no reason not to shoot me. But maybe we can at least hope for a world in which there are too few weapons to destroy civilization – where only individual nations (and not all of society) are at risk. That would at least be a step in the right direction.

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A little bit of history might be a good place to start.

The nuclear attacks against Japan were effective militarily and the possibility of a nuclear war with the Soviet Union was terrifying. But at the same time President Eisenhower realized that harnessing the energy from so tremendous an explosion might be useful. In 1953 Eisenhower gave his famous “Atoms for Peace” talk to the United Nations General Assembly, suggesting that even the most powerful of weapons might be able to be put to use on behalf of humanity – five years later this idea was turned into the Plowshares Program.

Although Plowshares had high aims it was delayed right out of the box by a moratorium on nuclear explosions. When nuclear testing resumed peaceful nuclear explosions were taken seriously enough by both the US and the Soviet Union that the two nations signed agreements over the maximum yield per device (150 kT) and the maximum yield from a series of explosions in a single project (1500 kT). And when testing resumed in 1961 both nations started their peaceful testing. Over the course of the next decade or so the US set off 27 explosions in Alaska, Nevada, and New Mexico; these were more than matched by the 239 detonations on the Soviet side.

Looking at these tests today it’s tempting to ask what they were thinking. Today we think of nuclear annihilation, blasted cities, and radioactive fallout – and that’s not even getting into the myths and misconceptions that so many have. So thinking about using nuclear explosives to dredge a harbor seems not only dangerous but downright silly. So was Eisenhower and the scientists he tasked with Project Plowshares all a bunch if idiots?

It’s easy to look at these tests today as just another wacky idea from a more idealistic and naïve era – among the reasons for giving up on the Plowshares program was the environmental impact of the explosions, not to mention the radioactive contamination of natural gas liberated by the Gasbuggy test. But we should also remember that these tests began in an era that was far less environmentally conscious than today and at a time when we knew far less about the effects of nuclear weapons than we do today – closer to the start of the nuclear age it was perhaps more tempting to try to find a silver lining. With the world still recovering from a tremendously destructive war, caught in the Cold War, and worried about nuclear war it must have been tremendously tempting to try to find something to do with nuclear explosives other than blowing each other up. We might joke today about the foolishness of some of the Plowshares projects, but I would hope we can also respect the optimistic audacity of Eisenhower’s vision; a former warrior in a simpler era trying to find a way to use these incredibly powerful weapons for the benefit of humanity.

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Most of radiation safety falls into the category of regulatory compliance, and the majority of our regulations either directly or indirectly are aimed at minimizing the chance that a person will develop a radiogenic cancer.  Virtually all of our radiation dose limits are largely aimed at minimizing the chance that someone might develop cancer as a result of avoidable radiation exposure.  If cancer were to be either defeated completely or become manageable (such as hypertension or diabetes, for example), many of these limits may no longer be as important.

Although there is a great debate over low-dose radiation effects, this debate may become moot in a post-cancer world.  If cancer is preventable or treatable, the presence or absence of a threshold dose for carcinogenesis will be of scientific interest, but we may be able to worry less about radiation exposure below thte threshold for causing deterministic effects – skin burns, acute radiation sickness, and so forth. Thus, radiation safety practices may return to those of an earlier era – preventing burns and excessive organ dose.

Other things may change, too.  How much would we worry about medical radiation exposure in a world without cancer?  Would the public be more accepting of nuclear energy, or would concerns of global warming become even more pressing?  Would radon remain an issue of concern to us if lung cancer were no longer so frequently fatal?  Would we continue to worry about radiation dose to the environment?  And how would we practice ALARA (the philosophy that radiation exposures should be kept As Low As Reasonably Achievable)?

This last question, in particular, is interesting to consider.  Although I’ve heard a few comments to the effect that ALARA may become a meaningless concept if there is a threshold radiation dose, I disagree.  To me, the key word in ALARA has always been “reasonable” – we should do what we can to keep radiation dose as low as reasonably achievable.  If we are no longer concerned about developing cancer, then it may not be reasonable to try to maintain exposure at very low levels – there are thresholds for deterministic effects (skin burns and radiation sickness, for example, that occur at high doses), and what would be reasonable would be to ensure that we do not exceed these levels (with a comfortable safety margin, of course).  ALARA would remain in place as a concept, just at a higher level to reflect the higher radiation doses needed to cause deterministic effects.

Of course, we can’t necessarily assume that a world in which cancer has been beaten is the same as a world without cancer at all – it could be a world in which cancer can be treated and managed; a world in which cancer still occurs, but is manageable.  In this case, we might treat cancer like diabetes – more than a nuisance, but less than a likely death sentence.  In this case, we would still want to avoid cancer, if only to avoid the treatments needed to keep it in check.  On the other hand, the allowable dose might be increased – if the risk of death per rem (or Sv) is substantially reduced, then perhaps we could accept a higher dose in order to gain additional benefits such as the ability to perform more “hot” work, to receive a higher level of medical diagnosis, and so forth.  Dose limits would not go away; but they could be relaxed to avoid the nuisance and expense of cancer, as opposed to fear of death from cancer.

Having said all of this, if a successful cancer treatment were announced tomorrow, I’m not sure that I would expect to see new radiation dose limits announced the next day.  Probably not even the next year.  For one thing, it would take time for the public to understand that cancer is no longer to be as feared, and it will take even longer to realize the implications of this for radiation safety regulations and practices.  Old habits do not change immediately.  It is also reasonable to assume that concerns for the environment (and radiation dose to the environment) will remain, notwithstanding the fact that cancer is not widely seen in wild creatures.  And, finally, changing radiation dose limits to reflect the new facts of cancer treatment may not be a high priority for either the regulators, nor for the elected and appointed officials who may find it difficult to explain why they feel they should allow a higher radiation dose to their constituents.  Gaining enough information to satisfy ourselves that cancer truly is manageable (or even beaten) will take time; changing decades-old opinions will take even longer – but I would like to be there when it happens.

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One thing that our hydrogeologist will find out is that tritium, although produced naturally in the atmosphere, is also produced in copious quantities by nuclear weapons testing. So it’s fairly easy to assume that the excess tritium showing up in the aquifer was from the era of atmospheric nuclear weapons testing – an era that peaked in the late 1950s and had largely ended in the early 1960s. So our hydrogeologist can make the assumption that tritium in the groundwater had to have entered the water in the 1950s or 1960s – the fact that it just showed up in his well means that it took a half-century or so to reach him. And with that, he can calculate how quickly the groundwater flows through the aquifer and he can start to make some good guesses as to the properties of the aquifer and whether or not it is being over-pumped.

Another of my professors used radioactive carbon-14 in a similar manner, except that he was using it to date layers of ice in Antarctic glaciers. Again, looking for the peak levels of C-14 helped to nail down the age of the ice in one location, and that could be used to date the layers around it. In both of these cases, the radionuclides could be used as tracers – to help trace the path of the radioactivity and of the medium it was in – and as “time markers” in the natural world. And in both cases the amount of radioactivity present was far too low to have any health impact at all.

A paper that was published yesterday in the Proceedings of the National Academy of Sciences is the first to suggest that radioactive cesium (the nuclides Cs-134 and Cs-137) can be used the same way, although this isn’t the angle that is being played up in the media. Here’s a little about it.

The backstory (as it were) is that bluefin tuna travel the Pacific – as do a number of other species – and it’s reasonable to wonder if they might be exposed to radionuclides in one location and to transport them to another. That’s what the authors of this study, Daniel Madigan, Zofia Baumann, and Nicholas Fisher set out to study. So Madigan took samples of some tuna caught off the coast of Southern California and sent the samples to Fisher and Baumann, who found traces of radioactive cesium in the flesh.

Before going further it’s important to note that all radioactive cesium on Earth is artificial. But that doesn’t mean that all of the cesium found is from Fukushima – there is cesium in the soil from the atmospheric nuclear weapons testing as well as from the Chernobyl accident. In fact, it is fairly easy to find Cs-137 just about anywhere in the northern hemisphere – dig up the soil in pretty much any location and you’re bound to find Cs-137 within a foot or so of the surface, and many trees whose roots penetrate these soil layers will have traces of Cs-137 in their wood. So it’s reasonable to wonder if the radioactivity found in the tuna came from Fukushima or from the background sources.

There are two primary nuclides of radioactive cesium – Cs-134 and Cs-137. The latter is long-lived with a half-life of about 30 years; we still have over a quarter of the Cs-137 from nuclear weapons testing and over half of what Chernobyl put into the environment. Cs-134, on the other hand, has a half-life of only about 2 years. The Chernobyl accident took place 25 years ago and we’re down to less than one tenth of a percent of Chernobyl-produced Cs-134, and far less from weapons testing. The bottom line is that the presence of Cs-134 would indicate unequivocally that the cesium in the tuna came from Fukushima.

And in fact, that’s exactly what the authors found – the presence of both Cs-134 and Cs-137, indicating that the tuna picked up radioactive cesium off the shores of Japan and carried it across the Pacific to the US tuna-fishing grounds. So the next question, I guess, is whether or not we can still eat sushi, or if the tuna is too “hot” for human consumption. After all, we are really good at detecting trivially low levels of radioactivity – we can detect radioactivity at levels far too low to be a problem. And, incidentally, I should also point out that there are other, more pressing concerns about tuna – chief among them mercury, to the point that the Food and Drug Administration has advised limiting uptake of some species to a few servings weekly. By comparison, the cesium is a trivial concern.

In this case, we would normally expect to find about a Becquerel (Bq) or so of Cs-137 in every kilogram of tuna caught in the ocean – that’s the background level. What Fisher, Madigan, and Baumann found was a little over 6 Bq per kg of Cs-137 and about 4 Bq/kg of Cs-134 – both being clearly higher than expected. On the other hand, they also found 30 times as much natural potassium-40 in the fish – up to 367 Bq/kg – from the potassium that every living organism relies on as part of its fundamental biochemistry. In other words, we can detect the Cs, but at such small concentrations that it poses no health risk at all. So would I eat sushi from the tuna that Madigan tested? Gladly (and voraciously). And if you have any that you don’t want, let me know and I’ll take if off your hands!

OK – so the lab work showed some radioactivity from Fukushima wound up in their fish, but they did NOT find a health hazard – what they found was a useful tracer. Just as tritium can be used to trace (and to time) the flow of groundwater and carbon-14 can be used for the same purpose with glaciers, Cs-137 and Cs-134 can be used to trace the migration of animals throughout the Pacific, and possibly further. And this could end up being a very positive side effect of the Fukushima accident – a better understanding of the Pacific ecology – call it the scientific and ecological fallout.

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Test launch of the new Russian Bulava missile

First we got the bomb and that was good, ‘cause we love peace and brotherhood.

Then Russia got the bomb, but that’s OK ‘cause the balance of power’s maintained that way.

Who’s next?    From the song “Who’s Next” by musician, satirist, and mathematician Tom Lehrer

An early American nuclear submarine, the USS Scorpion, was actually constructed twice – the first hull was abruptly extended by over 130 feet and the boat was renamed the George Washington. Today we’d say that it was “re-purposed” from a fast attack submarine to become the world’s first ballistic missile submarine. Launched in 1959 the George Washington was one of the nation’s highest-priority projects, forming the least vulnerable leg of the nation’s nuclear triad (the other legs being bombers and missiles). The chief advantage of the ballistic missile boats – boomers is what we called them – was their relative invisibility; unlike bombers and missiles a boomer could simply go quiet and vanish into the depths of the sea. Even we didn’t know exactly where they were, and the later boomers were so quiet that even at close range they simply blended in with the background noise of the ocean. In the fast-attack boats we somewhat derisively said that the boomers’ mission was to “hide with pride” and we made occasional rude comments about them and their crews. But the fact remained that they had a tough job – to remain at sea and undetected for months at a time and, if the need arose, to rise to missile-firing depth to launch an attack against our foes – all the while knowing that they would be the most-sought targets on the planet.

At the height of the Cold War the US had just over 40 boomers, each carrying at least a dozen missiles and each missile holding up to 10 nuclear or thermonuclear warhead. With a bit of Hollywood hyperbole the movie Crimson Tide claimed that the skipper of an Ohio-class boomer (the Trident submarines) was the third most-powerful person in the world, able to rain nuclear destruction down on any foe within 6000 miles. Today we have need for fewer boomers than in past years and the US is down to 14 Ohio-class boats. But with as many as two dozen missiles each, even the pared-down boomer force is a formidable force.

The Soviets launched their own boomers fairly quickly with the diesel-powered Hotel class boats in 1959 and the nuclear-powered Yankee class a decade later. The Brits were the next up, launching their first Resolution-class boat in 1966 and the French joined the party a half-decade later with the launch of the Redoutable. Rounding out today’s nuclear-powered boomer club are the Chinese, who launched their first nuclear-powered boomer in 1981.

The world, of course, continues to change and the quest for boomers is no exception. After all, the US figured out how to insert a missile compartment into a submarine hull a half-century ago – that level of technology is well within the grasp of every one of today’s nuclear powers. So today we find that not only are the American, Brits, Russians, and Chinese all developing their next generation of nuclear-powered boomers, but the Indians are developing their own indigenous nuclear-powered ballistic missile boat as well, and even Israel and Pakistan are rumored to have or to be developing diesel-powered submarines that can launch nuclear-tipped missiles. It seems likely that, before too much longer, every nuclear nation (except perhaps North Korea) will have its own undetectable nuclear deterrent force. The question is whether this is good or bad.

The best answer is probably “yes” – that the proliferation of boomers can serve to either stabilize or to destabilize whatever nuclear balance that might exist. Here’s why.

First, we can pretty much take the American, British, French, Russian, and Chinese boats off the table – these nations are all well-established nuclear powers and they all know that they can count on the others to act rationally. We are comfortable that the Russians won’t wake up one morning and decide to launch their missiles against us, just as they have that same confidence in the Chines and the British. But this level of confidence is borne of decades of competition – if the Russians didn’t launch their missiles against us during the Cuban Missile Crisis and if we didn’t attack them during the Berlin airlift or after the 1986 shoot-down of a passenger jet then it’s likely that neither side will use its missiles precipitously. But can the Indians trust the Pakistanis to act rationally as we trusted the Russians and the Chinese? And does Iran trust the Israelis?

I would suggest that, during the Cold War ballistic missile boats served to help stabilize the situation. With both sides knowing – beyond the shadow of a doubt – that the other side possessed a relatively invisible nuclear deterrent and the willingness to use it each side has an incredibly good reason to stay calm during crises. Had this balance of terror been upset – had the Soviets, for example, felt that they could take out the American boomers, there might have been the temptation to do so, possibly emboldening the foe to launch a pre-emptive war. Alternately, had the Soviets not possessed their own boomers the US might have been tempted to launch an all-out strike to devastate their global foe, secure in the knowledge that we could launch our missiles without much fear of retaliation. India and Pakistan might be building towards this level of equality – each nation armed with nuclear weapons and each striving to field nuclear missile boats – we can hope that these nations remain more or less in step so that neither gains a decisive advantage. But what about other situations in which there is no pretense of balance, and in which there might not be for some decades? It seems unlikely that Israel will feel like launching an unprovoked attack against its foes, but might one of its foes be prompted to attack Israel to forestall an anticipated Israeli attack? And what if North Korea were to develop a ballistic missile submarine – might they feel capable of attacking the South, secure in the knowledge that their boomers might be able to attack the South and to position themselves off the American coast, ready to attack should we come to the aid of the South?

It could be that a deterrent only works when each side can deter the other – that a one-sided deterrent force is unstable in the long run unless there is a degree of trust and understanding between foes. Perhaps a balance of terror is the most stable situation we are capable of pulling off. If so, we need to take a serious look at those parts of the world in which there is a lack of mutual understanding coupled with animosity and a mismatch of power. Is there an answer to this – will Israel’s foes allow their opponent an unanswerable weapon (and, for that matter, will anyone if this trend continues to spread)? Or can the stable leg of a nation’s nuclear triad actually serve to undermine the very security it purports to uphold? I guess we’ll find out.

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As a scientist the question is not simple, but it’s also fairly straight-forward. To start with, calculating radiation dose from a given level of contamination is fairly straight-forward and calculating dose is the first step towards figuring out the risk. Although there is some uncertainty about the risks of exposure to low levels of radiation, we can at least put an upper bound on the risks. So from a scientific standpoint the question is fairly straightforward – how much risk are we willing to accept and what level of contamination corresponds to that risk?

Consider the Japanese example – at the start of their evacuation their screening criterion was 13,000 counts per minute (cpm) and anyone with more than this level of contamination required decontamination (an ordinary Geiger counter such as what the Japanese used normally read less than 100 cpm). Soon after the evacuations started authorities realized that there were going to be lot of people with higher levels of contamination; as a result they upped their limits to 100,000 cpm. As a scientist I can tell you that this level of contamination doesn’t pose much risk to the people who are contaminated. But is this level of contamination acceptable to those who are contaminated? I’m not sure how the Japanese reacted – I haven’t seen that information – but I’ve seen plenty of Americans who have trouble accepting even natural background radiation (depending on the detector this might be anywhere from 50 to a few thousand cpm) let alone 100,000 cpm.

So where do we draw the line? Do we impose limits that are safe (but likely to cause worry and heartache) and that are comparatively easy and inexpensive to achieve, or do we set limits that are as close as possible to natural background radiation levels (which will please – or at least will not worry – the greatest number of people) even those achieving these limits is likely to add little additional public health benefit and will come at exorbitant cost? And just as important – do we continue to clean up contamination that poses no public health risk if the public demands it (consider, for example, that today’s cleanup limits are based on the ability to detect contamination more than on the risk that it poses)? How many billions of dollars do we spend to placate the fears of those who don’t know much about the health effects of radiation?

That last sentence might have sounded unduly harsh, but it is a question that needs to be asked. But before it can be answered here are a few more tidbits to consider.

First, we have to remember that psychosocial issues – and the health effects they engender – have been the most consistent health risk from the Chernobyl accident and it is not unreasonable to think that the same will likely be the same in Fukushima. It is easy to scoff at worries that might not be grounded in science, but these worries are real nevertheless, and they have a long reach. The 330,000 who were forcibly relocated after the Chernobyl accident have experienced elevated levels of depression, substance abuse, and suicide as a result of their experiences. Whether or not they are at risk from radiation is, to some extent immaterial – their fears and anxiety have caused very real problems. Similarly, if we force people to accept contamination levels that, while posing little or no health risk, are alarming to the public it may well be that people will die as a result of the elevated levels of anxiety and depression and the concomitant risks of suicide, depression, and substance abuse. It doesn’t matter if a person is sick from radiation or from anxiety – they are still sick.

We also have to recognize that spending money is – to an extent – risky. Governmental costs that are distributed across society take money out of the pockets of taxpayers. This leaves less money to, say, replace worn tires; less money to pay for doctor’s visits; less money for a healthy diet. So if we are talking about hypothetical lives lost due to depression and other mental health effects then we must also talk about hypothetical lives lost due to the distributed expense of cleanup, not to mention the risks from construction (or deconstruction) activities, excavation, traffic accidents (from transporting rubble), and so forth.

So we still have the question – how far do we clean up if there’s a radiological or nuclear attack? Deaths are deaths, whether caused by radiation exposure, radiation-induced cancer, traffic accidents, worry, or something else. So how do we compare these real and hypothetical risks? And can we compare them well enough to develop – in advance of an accident – a reasonable cleanup recommendation?

Right now there is no clear answer to these questions. State and federal agencies are all carefully dodging the question under the guise of it being a local issue (this one is popular among the federal agencies) while local agencies don’t want to come out with a number today that might be fought and argued over for years to come.

It would be easy for me (or any other health physicist) to calculate a number that would try to balance all of these risks and to pontificate about how any other number would be unreasonable. But the fact is that I don’t have any more of an answer than anyone else. There is more to this topic than pure science – I might be qualified to crunch numbers, but I’m out of my depth when it comes to the political, psychological, and social matters. But it might behoove us to let scientists work directly with politicians and members of the public today to at least get a start on figuring out what level of contamination might be considered acceptable should we have a radiological or nuclear emergency – the more work we can do today to figure out what might be acceptable (both scientifically and socially) the more quickly we can decide how much cleanup we will need to perform.

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The lead speaker, Dr. Gregory Matloff, started off by pointing out that anything in orbit is a weapon, if only by virtue of its position and speed. If you take a ton of metal moving at 17,000 miles per hour and drop it a few hundred miles onto someone’s building, well, that building is going to cease to exist. Think about all of the energy that’s needed to lift a satellite into orbit – a major chunk of that energy is released when the satellite crashes back to Earth.

Matloff also talked a little bit about the threat that asteroids pose to Earth, pointing out that the next “dinosaur killer” is out there somewhere. He’s right, of course – there is general agreement among astronomers and astrophysicists that the Earth will be slammed again at some point and the question is “when” and not “if” it happens. It behooves us to learn how to move asteroids out of a collision path if we’re to have the ability to save ourselves. But as Matloff points out, anyone who can move an asteroid out of the way can also move it so that it drops on an enemy’s head.

The next two speakers, Jeff Kueter and Taylor Dinerman, noted that space is already weaponized and that space warfare is already taking place, even if space itself is not the battlefield. To take the most obvious example, the only way to communicate with our satellites – the only way they’re useful to us – is through our communications with them; jam the communications and the satellites are useless. This has already happened, in fact – jamming GPS signals is a well-developed science – and jamming other signals is no more difficult (not to mention attacks against the ground stations that control the satellites). They went on to point out that the United States and Russia are the nations most reliant on space for both commerce and war-fighting – this makes them the nations with the most to lose as well. If North Korea (for example) attacks our satellites in orbit we lose our capabilities and they are unaffected. Shooting down satellites (which both China and the US have demonstrated the ability to do) can fill near-Earth orbit with debris, filling the airwaves with radio jamming signals can render satellites mute and uncontrollable – these technologies are already developed and in use.

Closing out the panelists was astrophysicist Neil DeGrasse Tyson, certainly the world’s most famous astrophysicist and one of the world’s most famous scientists. Tyson, while disclaiming direct knowledge of space weaponry, also pointed out that physics places limits on anything in orbit, weapon or no – what matters (to paraphrase) is the mass, speed, and altitude because these are what give an object its energy. After discussing the merits of various asteroid diversion schemes (hint – blowing one up is not a good way to go since then we’ve got thousands of incoming asteroid bits instead of just one) – he also pointed out that it is far easier for one satellite to attack another (hopefully vaporizing it with an advanced weapon instead of blowing it up and strewing still more junk in orbit). Like the other panelists, Tyson didn’t seem to put much stock in the Outer Space Treaty, pointing out that it seems unlikely that the most developed nations will join hands and sing Kumbaya in space. National interests will likely trump feel-good treaties – especially those without any real teeth.

During the discussion Tyson made another interesting point – in preparing one of his many books he’d spent some time looking into the motivations behind the world’s most expensive projects and he’d found only three common themes: war, commerce, and religion. The pyramids, the space program of the 1960s, the Manhattan Project, the cathedrals of Europe, the voyages of the Age of Exploration, the Crusades, and much more – Tyson pointed out that all of these came down to one or more of these three basic themes (playing on this theme he also suggested that the fastest way to get people to Mars would be for the Chinese government to “lose” a memo outlining plans for a Chinese military base on the red planet – facing the prospect of a rival military base on Mars he speculated that we’d need a few months to design and build the spaceship and nine months or so to reach Mars, considerably faster than the current non-plans).

The evening ended less inconclusively than I would have expected. There seemed to be fairly general consensus that, while there might not be any nuclear weapons in outer space, it is already militarized. The question is more what level of control we might have over the militarization. It occurred to me that the current limits over chemical, biological, and nuclear weapons might give some insights into what we can expect in space – many nations have one or more of these weapons, but enlightened self-interest (in a nuclear exchange, everybody loses) has kept that particular genie under control (if not necessarily in the bottle). In spite of everything, and in spite of some uses by bit players (e.g. the use of chemical weapons in the Iran/Iraq war) the fact remains that there has been no large-scale use of non-conventional weapons in over a half-century. It could be that mutual fear and caution can accomplish what good intentions alone cannot.

It was also clear that nations might contravene treaties but they are more loathe to work against their best interests. Ironically, it could be that the best way to dissuade the Chinese (and any other nation with anti-satellite capabilities) might be to give them a bigger stake in space. When they have as much to lose as we do, they also have as much to gain by helping to safeguard low-Earth orbit – and it won’t take Kumbaya to get their help.

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A high-activity Sr-90 source from the former Soviet Union

A dirty bomb is not a good way to kill lots of people, but it is a great way to scare the hell out of a population. There are reports that Saddam Hussein investigated the possibility of making an RDD in the 1980s and gave up on the idea because it simply wasn’t deadly enough. On the other hand, people are scared of radiation – even in the absence of a genuine radiological threat a dirty bomb attack can still cause deaths from panic, anxiety, and even traffic accidents as people flee the scene (or the city) unnecessarily. I would suspect that by now most terrorist groups understand the relative lack of medical risk to people. I would also suspect they know full well that they also know that, in spite of the relative lack of medical risk, a dirty bomb attack would be tremendously disruptive and that it would cause an enormous economic impact to whatever city was affected. So this means that we’ve got to be serious about controlling radioactive materials – and we’ve got to take seriously reports of radioactive materials trafficking. Even if the radioactivity itself poses little or no risk to the public, we still have to remember that any dirty bomb attack will likely have a significant impact.

This makes recent reports of radioactive materials smuggling a bit troubling.

A few weeks ago, for example, there was a report that the Armenians had broken up a strontium-90 deal. Strontium-90 is one of the nuclides thought more likely to show up in a dirty bomb – there is a ton of it in the world (it is made as a product of nuclear fission) and there are some very high-activity sources in the nations of the former Soviet Union. To give you an idea of the potential risk from Sr-90, consider that 1 curie (1 Ci) can cause skin burns if you hold it in your hand for even a few minutes. Now superimpose on that the fact that, in 1999, some woodsmen in the nation of Georgia found a single source that contained 40,000 curies of this nuclide – it had once been used to power a Soviet-era meteorological station – and there are still sources of this activity (and higher) that are not yet accounted for. The fact that two Armenians were busted trying to sell Sr-90 is not necessarily alarming in and of itself – that would depend on how much they were trying to sell – but it is worth noting.

Also worth noting is that at about the same time the Turks arrested someone trying to smuggle a small quantity of Cs-137 from Georgia. Cesium-137 is another of the nuclides we’re particularly concerned about as a potential dirty bomb component. Like Sr-90, Cs-137 is produced in large quantities in nuclear reactors and, also like Sr-90, there are a large number of high-activity Cs-137 sources in the world. In fact, there’s very likely more Cs-137 in the world than Sr-90. Cs-137 sources have killed people around the world – something that can certainly happen here as well if we let down our guard.

The bright side of these events is that at least we are seeing the nuclides that we consider most likely to be used against us. It would concern me, for example, if the nuclides that were found kept surprising us. Law enforcement agencies should be finding these nuclides for exactly the reasons that they are considered likely to be used in a terrorist attack – they are common, they are frequently used in settings in which radioactive materials security is not necessarily a high priority, and they are often present in high-activity levels. There’s more than that – these nuclides also have a fairly long half-life (which keeps them from decaying to stability too quickly), they both have a fairly high specific activity (so they can pack a lot of activity into a relatively small package), and more. But, again, it is somewhat gratifying that our logic seems to be holding up – that the most commonly smuggled nuclides are pretty much exactly what we’d anticipated.

On the negative side, the fact is that we continue to see a continuing low background level of radiological smuggling – in spite of the fact that such sources are unlikely to cause massive casualties, criminals and terrorists retain their interest in striking with these weapons. This means that not only need to maintain our vigilance to keep intercepting these materials before they can be used maliciously, but we also must maintain our efforts to secure them. The Department of Energy, through its Global Threat Reduction Initiative (GTRI) has done an enormous amount of work to help safeguard sources in the US and overseas – their work has already secured millions of curies of radioactive materials, not to mention thousands of bombs’ worth of highly enriched uranium. When you consider that a single RDD might cause tens or hundreds of billions of dollars of damage and clean-up costs (not to mention the societal and long-term economic impact), the millions of dollars spent to secure these sources certainly seems to be money well-spent. One can hope that their work will be permitted to continue, rather than being subjected to the typical vagaries of the political process.

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Consider – a nuclear attack would be hugely destructive; far more so than any terrorist attack in history. Just as we waited to confirm al Qaeda’s role in the September 11 attacks before we attacked Afghanistan, so too would we need to be absolutely sure to retaliate correctly to a nuclear attack.

In the “good old days” of the Cold War there were fewer nuclear nations and no terrorist groups who wanted to use them against us. What we worried about were bombs that arrived at the tip of a missile or in the belly of a bomber – weapons that came with a return address as it were since we could (presumably) trace the trajectory back to the point of origin. Planning for an all-out nuclear attack ruled out a number of possibilities – massive numbers of nuclear weapons arrive through air or space, not by UPS. But things are different today – there are more nuclear-capable nations (a number of which lack both large numbers of weapons and missiles), there are terrorist groups who have expressed a determination to use nuclear weapons against us, and there are an increasing number of possibilities for these groups to try to get their hands on them. This means that trying to sort out who attacked and where they got their nuclear weapon will not be nearly as simple as we had once expected.

In Tom Clancy’s novel The Sum of All Fears there is a scene in which savvy nuclear forensic experts pinpoint the exact reactor in which the plutonium comprising a nuclear weapon originated. A neat scene – but is it plausible? Say, for example, a nuclear weapon goes off in one of our major cities and we can figure out that it contained plutonium that originated in Russia. Do we blame the Russians for the attack and retaliate, do we accuse the Russians of having sold a nuclear weapon to a terrorist group (or to a rogue nation), do we decide that a terrorist group (or a rogue state) managed to get their hands on Russian plutonium, or do we suspect that whoever attacked us just happened to produce plutonium that was identical to something produced by a Russian reactor?

In 2010 the National Academies of Science concluded that America was losing its touch in nuclear forensics, recommending that actions be taken to restore our Cold War capabilities. To help address this need the government has opened a new facility at the national laboratory in Oak Ridge – the place where some of the first weapons-grade uranium was produced – the National Uranium Materials Archives. As reported in the Knoxville press, this collection will help nuclear forensic specialists to pinpoint the source of nuclear materials that are used or intercepted.

The idea behind nuclear forensics is that every bit of enriched uranium or plutonium is unique, a product of the environment in which it was produced. Plutonium, for example, is produced in nuclear reactors, when a U-238 atom captures a neutron and begins a process that leads to Pu-239. But reactor fuel contains more than just U-238, U-235, and Pu-239 – consider these, for example:

• Fission products from U-235 fission
• Various nuclides of plutonium from neutron capture (Pu-239, Pu-240, Pu-241)
• Fission products from the plutonium nuclides
• Impurities from the original fuel and the nuclides formed when they capture neutrons

The concentrations of all of these radionuclides will vary in a way that, in theory, can identify the exact nuclear reactor in which a batch of plutonium was produced. And, with careful analysis, one can even make some very educated guesses as to where a batch of uranium was mined, processed, and enriched. Putting all of this information together with the sort of samples Oak Ridge is collecting can help us to pinpoint the origin of a batch of uranium or plutonium used in a nuclear attack. And with that information, should there be a nuclear attack against us or, for that matter, against any other nation, we just might be able to figure out who attacked us and where they got their weapon.

In the wake of the Cuban Missile Crisis President Kennedy foresaw “the possibility in the 1970s of the president of the United States having to face a world in which 15 or 20 or 25 nations may have these weapons.” This obviously didn’t happen, thanks in large part to the Treaty on the Non-Proliferation of Nuclear Weapons (usually abbreviated as the NPT). But we have seen the number of nuclear states increase in the last decade and there is the possibility that this number could grow even further in coming years and we increasingly face the possibility that such weapons will be developed or obtained by nations that may be tempted to sell or to give them to terrorist groups for use against us or against our allies.

Consider, for example, a North Korea that, in the aftermath of a successful 20 kiloton nuclear test, sold a nuclear weapon to a terrorist group who then used it to attack Tel Aviv, Riyadh, Paris, Washington DC, or another major city. Delivered in a shipping container or rented truck, the weapon would arrive without a return address – we would have only the claims of various terrorist groups to go by in trying to figure out who had attacked. But if nuclear forensics could fingerprint the weapon as containing uranium or plutonium from North Korea we would know who made the weapon and we could hold them accountable for their role in the attack. But we can only do this if we have the capability of identifying the weapon as having originated in that nation.

Absent solid knowledge of the precise composition of North Korean uranium and plutonium coupled with a robust nuclear forensics capability we might well be unable to figure this out or to be able to convincingly justify retaliation. This is why it is vitally important that we retain our skills in nuclear forensics and why we need to build our uranium materials archive – every nation that has or is developing nuclear weapons has to be made fully aware that, should one of their nuclear weapons be used in an attack anywhere in the world, their role in the attack will come to light and they will be punished.

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Every so often it seems that dental radiation briefly makes an appearance as something that we wonder if we should be concerned about. In 2004, for example, the Journal of the American Medical Association published a paper purporting to show that dental x-rays were linked to low birth-weight children (the authors claimed that dental radiation somehow inhibited thyroid function, causing low birthweight children). The only problem was that the amount of radiation exposure delivered to the thyroid is far lower than anything shown to be able to have any impact whatsoever, and the authors failed to perform a relatively simple test for thyroid hormone levels that could have shown them to be right or wrong in their assertion. This paper was roundly criticized (including this fact sheet by the University of Texas Health Science Center) and to date there have been no other indications that dental x-rays can have any reproductive impact at all. As an aside – during my days as a radiation safety officer I had one pregnant patient whose dentist advised her to terminate her pregnancy after he found she was pregnant after receiving dental x-rays. Thankfully she asked for a second opinion because not even the most high-dose dental x-ray procedure can expose the fetus to enough radiation to cause problems.

Around this same time I was asked to consult on a British lawsuit in which patients were claiming that their dentist was taking too many x-rays, exposing them to unnecessary radiation. The problem was that, adding up the risk factors from the x-rays and comparing them to other risks, it turned out that the riskiest part of this procedure was the drive to the dentist and not the x-rays themselves. And that is if we place any confidence in radiation risk estimates at such low doses (on the order of a few millirem, or a few tens of microSieverts) – the Health Physics Society, the National Council on Radiation Protection and Measurements, and the International Commission on Radiation Protection all take somewhat different stances on this issue but all of these highly skilled and reputable bodies conclude that the risk varies between zero and incredibly low.

The latest round in this saga is a paper published in the journal Cancer just last month, suggesting that dental x-rays increase the risk of meningioma (a usually non-malignant tumor of the membranes surrounding the brain, and the most common form of brain tumor). But a careful reading from the standpoint of a radiation safety scientist leaves me unimpressed. Here’s why.

First is that the authors don’t seem to have calculated the radiation dose to the brain from the dental procedures they are concerned about. As any radiation biologist knows, radiation dose to the organ of interest is everything – every radiation dose-response hypothesis describes a relationship between radiation dose and cancer risk. Without knowing the estimated radiation exposure to the brain (specifically to the meninges) we can’t determine the probability of causation for the specific tumors and can’t see if there is any dose-response relationship. If radiation is causing these tumors then the number of “excess” tumors should increase as radiation dose increases – without knowing what the radiation exposure is then we cannot even guess whether or not radiation exposure is a reasonable explanation for the meningiomas that were seen.

In addition to a lack of dosimetric information the risk ratios reported by the authors are unimpressive. Most of the incidence ratios are very close to 1 (meaning that the cohorts studied have an incidence of meningioma very similar to that of the control group) and many of the groups had a ratio of less than 1. There are some groups with higher incidence ratio but these were only those who had received panoramic x-rays – not the more common bitewing x-rays.

It is also important that the dental x-ray history of those involved in the survey was based in the recollection of those surveyed – not on their dental records. I remember my grandfather (and later my uncle) taking dental x-rays, but I have no idea how many of these I had in my teens, and I have no idea how many of these were panoramic x-rays. I assume that, during my Navy days, I had annual dental exams but even here I honestly have no idea whether or not I had x-rays annually or if the Navy even gave me the panoramic x-rays. I have to admit that I am not a paragon of memory, but I’d wager a guess that my memory is no better and no worse than that of the average subject interviewed for this paper. The bottom line is that the closest thing to radiation dosimetric exactitude is based on the memory of those who were interviewed as a part of this study and memory is fallible and biased. At most, a study based on recollection is suggestive, at worst it is worthless. But it is also plausible to wonder if people with meningioma were more likely to recall a higher number of dental x-rays than those who were healthy.

So let’s take on the topic of dosimetry. Dental x-rays are low-dose procedures – according to the American Dental Association bitewing x-rays give a dose of about 4 mrem and full-mouth x-rays give a dose of about 15 mrem. Seventy sets of full-mouth dental x-rays would give a person a dose of about 10.5 rem – barely above the lowest dose (10 rem or 100 mSv) at which the Health Physics Society suggests that it’s scientifically acceptable to calculate a numerical estimate of risk (below this dose the epidemiology is quite fuzzy). And even at this dose the additional risk of cancer is about 0.5% above the background risk of 25% or so. This isn’t nothing – but it’s pretty low, and certainly lower than the excess risks suggested in this paper.

In fact, an earlier (2009) paper by Joanna Banerjee did show a dose-response relationship between radiation exposure and meningioma. But this paper determined the radiation dose and these doses were all far in excess of 10 rem (100 mSv). The doses reported by Banerjee and her colleagues are certainly high enough to cause problems –giving this paper more credence than the more recent paper that sparked this posting.

But all of this brings up a more fundamental point – that there is an assumption that even the slightest dose of radiation can cause problems and that the role of the author is to reveal these problems rather than to determine if they exist. There are any number of scientific papers that begin with the assumption that even the slightest dose of radiation will cause cancer and the goal of the author(s) is to tease out the relationship instead of trying to determine whether or not a relationship exists.  This may seem reasonable, but it’s sort of like a parent starting with the assumption that their kids are getting away with something, rather than a parent giving their kids the benefit of the doubt. When authors assume a priori that every adverse health effect is due to radiation then they are beginning by assuming the conclusion that they are trying to prove. When you start off trying to prove your assumptions then you will frequently be successful – we are good at finding what we are looking for.

The bottom line is that there may (or may not) be risk from dental x-rays, but there is unambiguous benefit that comes from having them. In addition to showing the dentist the location of potential cavities (or abscesses) dental  x-rays can also reveal osteoporosis, sinus infections, some tumors, and more. If we are to cast aspersions or raise cautions about dental x-rays then we must also acknowledge the benefits that accrue from them – to fail to do so will give us a skewed view of these procedures. And the paper discussed her not only assumes that all of the “excess” cancers are due to dental radiation, but it also fails to acknowledge these benefits.

The fundamental problem is that, while radiation can cause health problems, it takes far more radiation to do so than most people realize. Radiation can cause cancer, for example, but the cancer risk from 1 rem (10 mSv) of exposure (typical of a CT scan) is far lower than even the risk from driving (and may actually be zero). Similarly, radiation exposure can cause birth defects, but the amount of radiation required for this is far higher than most realize. Thus, radiation finds itself blamed for all sorts of things that it is simply unlikely to have caused.

And here is where I have to reveal my biases as a radiation scientist. I have to admit that I grow irked when papers such as this are published – papers that might make sense mathematically but that make no sense at all when considering the totality of what we know of radiation health effects. Anyone can take a radiation health effects slope factor and calculate a risk for even vanishingly low doses of radiation – but these calculations are meaningless because they are uninformed by reality and they are out of touch with the real world. As an example, I might calculate that an x-ray that gives one a dose of 10 mrem might increase my risk of cancer by 0.005%. Let’s face it – every time I push the “=” key on my calculator I’ll get an answer. But this answer neglects the advice of the Health Physics Society to avoid calculating a numerical risk estimate for dose of less than 10 rem, it ignores the statement by the ICRP that such doses are “trivial,” and it fails to acknowledge not only the risk from driving (1%) but also the background cancer risk of 25% or more. This not only skews the authors’ interpretation of their results but it also gives radiation a weight it does not deserve. I do not object to radiation being blamed for what it has (or is likely to have) caused, but I do object to its being unfairly blamed for effects that are implausible. In this case, unfairly blaming radiation from dental x-rays for causing meningioma is not only inappropriate in that it flies in the face of or experience and the recommendations of respected scientific bodies, but it might (ironically) do a disservice by dissuading people from receiving needed dental x-rays. If this happens then the net result of this paper – and others of its ilk – will be to the detriment of public health.

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Enrico Fermi at the blackboard

Nobel prize-winning physicist I.I. Rabi commented once that “In science we can’t let some guy from Podunk have the same vote as (Nobel laureate Enrico) Fermi.” Science has nothing to do with voting – I dislike gravity (especially when I step on a scale) but convincing my fellow citizens to vote against gravity (or to vote for a lower gravitational constant) isn’t going to change the way the universe works. The world is the way that it is and the job of science is to try to tease out the rules that describe its workings. No vote – no matter how overwhelmingly one-sided – will change the rules of nature. So why is it that a recent University of North Carolina (Chapel Hill) survey showed that belief in science continues to dwindle in the United States?

Consider how much our society depends on science – the generators that produce our electricity (and the motors and electronics that use it), our medicine, GPS navigation, computers, and everything else – even to try to support the Earth’s current population without a heavy reliance on science would be almost impossible, let alone letting us enjoy the standard of living to which we have become accustomed. Yet somehow there are an amazing number of people who accept the directions from their GPS units, search the web and send e-mail from their computers, fly around the country, and watch television – all the while decrying the science that makes their lives possible. How is it possible that so many can take so for granted the science that gives us the things we like in life while refusing to accept science when it becomes inconvenient (e.g. evolution, the use of genetically modified foods, or global warming)? And more – in our increasingly technical society, how many court cases revolve in part or in full on the jury’s understanding of science and scientific principles? Not only that, but there are those who not only don’t understand the science, but who refuse to understand the science – and who are even proud of their scientific ignorance. Is it even possible to have a Jeffersonian democracy – based on the collective wisdom of an informed electorate – in a scientific age when a significant fraction of citizens celebrate their scientific ignorance?

In the August 30, 2005 edition of the New York Times reporter Cornelia Dean wrote about some aspects of the lack of scientific literacy among the American public, citing work by Northwestern University professor Jon D. Miller. Professor Miller noted that “While scientific literacy has doubled over the past two decades, only 20 to 25 percent of Americans are ‘scientifically savvy and alert’” and that the rest “’don’t have a clue.’” In Professor Miller’s opinion “people’s inability to understand basic scientific concepts undermines their ability to take part in the democratic process.” Miller cites surveys showing that only about ten percent of Americans know what radiation is and that twenty percent do not realize that the Earth revolves about the Sun—something that scientists figured out more than four centuries ago. Miller also found that a troublingly large number of American adults are also unaware that DNA is the molecule that encodes the instructions for every organism, or even what molecules are.

Court cases are unlikely to turn on a juror’s understanding of astronomy—whether the Earth revolves around the Sun or the Sun around the Earth is probably not going to have an impact on any court case. But jurors who does not know that DNA is a molecule that is unique to every person on Earth—or even what a molecule is, for that matter—are going to need a great deal of education by expert witnesses before they can deliver a just verdict in a rape or murder case that hinges on DNA evidence. A juror who does not understand these matters is one thing—they may not know but they can be educated—a juror who refuses to understand because they are proud of their scientific ignorance is something else entirely.

Writing about recent trends in anti-intellectualism in the February 17, 2008 Washington Post, journalist and science writer Susan Jacoby comments on “the arrogance about (our) lack of knowledge. The problem is not just the things we do not know…it’s the alarming number of Americans who have smugly concluded that they do not need to know such things in the first place…The toxic brew of anti-rationalism and ignorance hurts discussions of U.S. public policy on topics from health care to taxation.” And Jacoby is one of only a few to comment on American anti-intellectualism, here are just a smattering of books and articles written on the subject in recent years:

• Bolstering anti-intellectual credentials, Steve Benen, Washington Monthly (September 15, 2011
• America’s growing anti-intellectualism, Paul Rosenberg, Al Jazeera (October 12, 2011)
• Idiot America: How Stupidity Became a Virtue in the Land of the Free, Charles P. Pierce (2010)
• Anti-intellectualism In and Out of Academe, Mary Churchill and Michael Brown, The Chronicle of Higher Education (August 8, 2011)
• Scientific Savvy? In U.S., Not Much. Cornelia Dean, The New York Times (August 30, 2005)

This list is just a start—consider George W. Bush’s boasting that “I remind people that, like when I’m with Condi I say, she’s the Ph.D. and I’m the C-student, and just look at who’s the president and who’s the advisor” along with the majority of Republican presidential candidates who have stood on stage and rejected the theory of evolution. The fact is that too many of us—whether in politics or in ordinary life—are not only uninformed in many areas of science but, indeed, just do not seem to care about their lack of understanding.

Anti-intellectualism is not a recent phenomenon in the United States. In 1963 Columbia University professor Richard Hofstadter (1916-1970) wrote a Pulitzer Prize-winning book Anti-intellectualism in America on the topic, but even Hofstadter was far from the first to raise this theme. In fact, Jacoby quotes American poet and essayist Ralph Waldo Emerson (1803-1882), who wrote in 1837 that “The mind of this country, taught to aim at low objects, eats upon itself.” Jacoby notes that “It is almost impossible to talk about the manner in which public ignorance contributes to grave national problems without being labeled an ‘elitist,’ one of the most powerful pejoratives that can be applied to anyone aspiring to high office. Instead, our politicians repeatedly assure Americans that they are just ‘folks,’ a patronizing term that you will search for in vain in important presidential speeches before 1980.” As Jacoby—and innumerable other writers throughout the history of the United States—pointed out, there is a very strong tension between the intellectuals who founded the United States and the tendency for the general public to be suspicious of those who comprise the nation’s intellectual elite.

The entire topic of anti-intellectualism reaches into virtually every aspect of American life and society. It has been decried by intellectuals on both sides of the political spectrum and it has been exploited by politicians, political commentators, social activists, and others—also on both sides of the political spectrum. In the increasingly complex world we live in—a world in which so much depends on our science and technology—rampant anti-intellectualism threatens our nation’s present and future security and prosperity. But unfortunately, something that has been so long-lasting a part in American society is hardly likely to go away anytime in the foreseeable future. This is not something to be proud of.

Note: I’d like to apologize for not posting last week – I’ll try not to miss again!

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A ring of weapons-grade plutonium

Fissile materials have been in the news a lot in recent years – Iran’s uranium enrichment program, North Korea’s continuing nuclear weapons program, the on-going nuclear security summit, and so forth. Given all of this attention this seems like a good time to talk about what fissile materials are and how they’re produced – and when they become a potential security problem.

Defining some terms is a good place to start.

Fission is the process by which a heavy atom (typically U-235 or Pu-239) splits into two smaller atoms (fission products), usually after being tapped with a neutron. The fission process releases a lot of energy – 200 million electron volts (MeV) per fission, compared to a few electron volts per atomic bond broken during combustion.

Fissile materials are materials that will sustain fission. As noted above, the most common fissile materials are U-235 and Pu-239. Fissile materials are produced either in a nuclear reactor (in the case of Pu-239) or by processing uranium to enrich the concentrations of the fissile isotope, U-235.

Natural uranium is uranium in which about 99.2% of the atoms are U-238 and about 0.72% of the atoms are the fissile U-235.

Enriched uranium is uranium in which the fraction of U-235 has been increased; depleted uranium is that in which there is less U-235 than found in nature. Reactor-grade uranium fuel contains between 3% to 6% U-235 (some reactors use lower-enriched fuel, some use a little higher) while research reactors – used to produce radionuclides for research and medical purposes – use uranium that is up to 20% enriched. Anything higher than 20% enrichment is banned by the Non-Proliferation Treaty except for the existing nuclear weapons states – weapons-grade uranium is enriched to 90% and higher, almost pure U-235. Incidentally, the nuclear reactors on American submarines and aircraft carriers is higher than 90% enrichment.

So – one fissile atom (U-235) is found in nature, but in concentrations too scarce to support fission while the other (Pu-239) shows only the barest hint of a presence. Neither is naturally found in concentrations that will make even a nuclear reactor (unless we are going to use heavy water or graphite to help slow the neutrons down to make fission more likely), let alone nuclear weapons – making fissile materials takes a huge effort to either enrich the U-235 to useable concentrations or to fabricate the Pu-239. Both processes have been used – both seem to be in use in North Korea and have been used by other nuclear powers – and both use very different processes.

Uranium enrichment is probably the best place to start. Both uranium isotopes – U-235 and U-238 – are chemically identical so it simply isn’t possible to chemically process uranium to turn natural uranium into reactor fuel or nuclear weapons. The only difference is the fact that the U-238 atom is just a tad heavier than its lighter sibling. But this small difference is enough. When uranium is mixed with fluorine to make uranium hexafluoride gas (UF₆) and then introduced into a rapidly spinning centrifuge the lighter ²³⁵UF₆ floats on top (towards the center of the centrifuge tube) of the heavier U-238 hexafluoride. Very slightly enriched uranium is collected by siphoning off the topmost layer. Repeat this process over and over – the more times the better – gradually produces uranium enriched anywhere from reactor grade to weapons grade.

The basic science of uranium enrichment is deceptively simple. The difference in mass between U-235 and U-238 is not much of a “handle” for engineers to grab onto and the amount of enrichment at each step is almost trivially small. This is why it takes hundreds or thousands of centrifuges to produce a meaningful amount of uranium. Coordinating and controlling this enrichment “cascade” is fiendishly complicated. Not only that, but centrifuges work most effectively at high speeds – whirling at hundreds of thousands of RPM and generating outlandish centrifugal forces that simply tear apart all but the strongest materials. Requiring fantastically precise manufacturing, these centrifuges are prone to failure – especially in programs that are still developing expertise.

There are other ways of enriching uranium – gaseous diffusion, electromagnetic separation, thermal diffusion, to name a few – but virtually all of them rely on the same principle of using the tiny difference in mass to sort out uranium atoms into the fissile and the rest. This is what makes uranium enrichment so difficult – and it’s one of the factors that makes plutonium production so attractive.

Plutonium and uranium are closely related chemically – they both reside among the actinide elements on the lower bar that lies beneath the main body of the Periodic Table. But closely related is not identical – unlike U-235 and U-238, plutonium chemistry is just enough different from uranium to make it possible to chemically separate the two elements. So if one has a mixture of plutonium and uranium, one can chemically process the mixture to remove the plutonium without having to go through the entire enrichment process. But first, of course, we have to make the plutonium.

Plutonium is produced in nuclear reactors – preferably reactors using low-enriched uranium. Reactor fuel that has 2% (for example) U-235 has 98% U-238. That U-238doesn’t fission well, but it captures neutrons quite nicely. So a U-238 atom that intercepts a neutron from fission will turn into a U-239 atom. This atom has a fairly short half-life and it quickly decays to form Neptunium-239, which decays in turn to form Pu-239, which fissions quite nicely. So to make Pu-239 all we need to do is to “cook” U-238 in a neutron field and then wait for the U-239 to go through a few radioactive decays. This happens routinely in every nuclear reactor on Earth – in fact, a significant fraction of reactor energy comes from the fission of Pu-239, Pu-240, and other plutonium isotopes that are produced during this same neutron capture.

Once the plutonium has been produced it has to be separated from the rest of the elements in the reactor fuel, but this is not necessarily a straight-forward process. The problem is that the reactor fuel has been irradiated and has fissioned for however long it’s been in the reactor – it is dangerously “hot” and has to be given a chance to decay until radiation levels are safe. After several months of decay the fuel is chopped into pieces and dissolved, after which it can be chemically processed to extract the plutonium. The requires an elaborate chemical processing capability as well as the ability to work in hot cells using remote manipulators – but these are tried-and-true technologies that are easier and lower-tech than uranium enrichment.

The bottom line is that there are two main paths to producing fissile materials. We can take natural uranium and, through herculean efforts, increase the fraction of fissile U-235 to levels that will sustain fission or that will make a weapon. Or we can use nuclear reactors to bombard natural uranium with neutrons to produce plutonium that we can then chemically extract from the spent fuel. Both systems have a long and proven track record, both have been mastered by many nations, and both represent paths to nuclear weapons.

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Author's photo of (at that time) an operating reactor next to one that was never completed

Growing up intermittently Catholic, I was taught about Limbo – a sort of antechamber to heaven that holds the souls of those who were never baptized by who had not committed a sin of their own. Those souls in Limbo aren’t admitted to Heaven, but neither are they sent to Hell – they are simply waiting.

At the moment, Limbo is a pretty good term for the status of nuclear energy in much of the world. As recently as March 10, 2011 the talk in the United States and elsewhere was of a nuclear renaissance – nuclear utilities were starting the decade-long process of licensing, site selection, and construction; taking the first steps towards reviving an industry that had been more or less in Limbo since the 1980s. It may be too much of a stretch to say that the nuclear industry was starting to crawl Heaven-wards, but it was starting to move in a favorable direction. However, even those faltering steps have been stopped. Once again, nuclear energy is in Limbo – not really thriving and not really dead. An interesting question to ask is why this is the case – why is it that nuclear energy’s proponents can’t quite get it revived while its opponents can’t quite land the death blow?

As far as I can tell part of the reason is that we are caught between our hearts and our heads. Rationally, nuclear energy makes sense – the facts line up in its favor. At the risk of going over well-trod ground (albeit briefly) nuclear energy emits no greenhouse gases (unlike fossil fuels), it can be put anywhere (unlike solar, tidal, geothermal, and wind), and – even with the well-publicized accidents at Three Mile Island, Chernobyl, and Fukushima – it is among the safest forms of energy. And lest you question this last point, hundreds to thousands of people die each year simply extracting fossil fuels from the ground – in comparison, in 2006 the World Health Organization found that fewer than 100 people had died in the 20 years since the Chernobyl accident (including deaths from both short-term radiation sickness and cancer) , nobody died from the Three Mile Island accident, and it is likely that few (if any) will die of radiation sickness or cancer from the Fukushima accidents. Even radioactive waste – long the bugaboo of anti-nuclear activists – can be safely contained, as I discussed in an earlier posting on this blog.

Of course there are also the concerns about the exclusion zone around Chernobyl and Fukushima – a lot of land has been contaminated and placed out of service. But if we are to look at that then we must also consider the square miles devastated by coal mining, the mountain lakes and streams laid to waste by acid rain; not to mention fish that die in hydropower turbines, birds killed each year by wind farms, or the naturally radioactive wastes produced by geothermal energy. And we haven’t even discussed the vast areas polluted by oil spilling from leaking pipelines, oil well blowouts, and sinking tankers. Huge swathes of territory have been devastated by our use of fossil fuels – by comparison, author Mary Mycio, in her fascinating book Wormwood Forest describes the Chernobyl exclusion zone as being one of the richest ecosystems in Europe. The environmental impact of nuclear energy – even at its worst – is no worse than that of fossil fuels. And, incidentally, nuclear reactors (during normal operation) actually put less radioactivity into the environment than do fossil fuel plants because of the geochemical association of fossil fuels and natural radioactivity.

The bottom line is that there is no rational reason not to use nuclear energy – its flaws are no worse than those of other forms of energy. That being the case, one might expect that even the recent accident would have the same impact on nuclear energy that the Gulf oil spill had on fossil fuels – little to none. So why is nuclear energy not the rational choice? Why have the (figurative) gates of Heaven not swung open for nuclear power?

The reason is that our decision to use (or not) nuclear energy is not a purely rational decision – the fact is that we make decisions based on emotion as much as on rationality, and one can no more argue emotion with facts than one can tune an engine using chopsticks. It’s possible, but unlikely and difficult. Pure rationality is the wrong tool to use when waging an emotional argument, but the scientists and engineers who design, build, operate, and stand up for nuclear power are usually ill-suited for using any other tool.

Leaving the pure facts aside, there are still good reasons for letting nuclear energy escape Limbo. In my younger years my father would take me hiking, camping, and fishing – he enjoyed sharing with me the woods, rivers, and mountain vistas. Today many of the mountains have been blasted into the valleys and the streams run red with acid mine drainage, hundreds of lakes are barren and nearly bereft of life, and the vistas are fogged with the detritus of burning fuel. We have to look harder and travel farther to share the same things with our children that our parents shared with us.

I also occurs to me that our major style of energy production today isn’t much different than it was ten thousand years ago – we used to burn wood, today we burn fossil fuels. I’d like to think that, with as much as our society has advanced, we can do better, and that “better” will likely include a mix of power sources that will almost certainly have to include nuclear.

Energy is what makes society work and the technology that has brought so many out of poverty, that has fed billions, and that has contributed so mightily to our current standard of living – this technology and all that comes from it tracks quite nicely with our use of energy. Billions of us live longer, healthier, and more fulfilling lives and these lives are better in large part because of the availability of energy. Billions more want to have the same lifestyle – can we deny them what we take for granted and what they strive for?

There are a lot of issues – maintaining our lifestyle, raising others to the same level, preserving the environment, moving beyond combustion as a source of energy, and so forth. Nuclear energy cannot be the only answer to these issues, but it must play a role. To deny ourselves this source of energy simply because it is distasteful to many just doesn’t make sense. But as neuropsychologist Drew Westen discusses in his insightful book The Political Brain, humans’ emotions have been with us far longer than have our intellects – unless we can appeal to both the heart and the mind we are unlikely to convince everyone of this. Popes John Paul II and Benedict XVI both voiced their belief that Limbo might not be a required aspect of Catholic theology, meaning that perhaps all of those souls have never been in Limbo after all. Would that it were as simple a matter to release nuclear energy from the Limbo in which it once again finds itself.

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Thought image via Shutterstock.

The unknown frightens us a whole lot more than the known – we can plan on how to deal with hazards we know about while the unknown leaves us unprepared. When my son was young, for example, he was afraid of the dark. Or, rather, he was frightened of the things he could not see – the suspected (but unconfirmed) monsters that might attack him in the night. I pretended to have the same fear as a child – in my case so that my parents would leave on the hall light so that I could secretly read a little longer at night. My son’s fears were honest (if ill-founded) where mine were more manipulative – aimed at snatching a little more surreptitious reading time.

Radiation phobia is ubiquitous in our global society. A huge number of people are frightened by radiation and their fear drives them into wild speculation about what the radiation might do to them. To those of us who understand the science behind radiation and its effects, these fears seem as silly as my son’s worries about monsters in the closet; to those who are frightened, our scoffing can seem uncaring and heartless – just as I am sure I seemed that way to my son on the fifth monster-search of the night.

We live in a society that depends on radiation and radioactivity. And at the risk of restating fairly common knowledge, it’s worth recounting some of this, if only to get it all in one place.

• About one-sixth of the world’s electricity (and a fifth of that in the United States) comes from nuclear power plants and, if we are to continue trying to bring electricity to both the developing and developed world without pumping more carbon dioxide into the atmosphere then we have few options other than to deal with the reactors and the waste they produce.
• Medicine saves or improves billions of lives each year using radiation and radioactivity for diagnosis and treatment. Absent this radiation we would be back in the days of exploratory surgery, watchful waiting, and guesswork for a huge number of people and their ailments.
• Research that we depend on to help make our lives simpler, better, and healthier utilizes radiation and radioactivity. Whether that research is aimed at understanding cancer, developing more productive (or more nutritious) foods, or teasing out pharmaceutical biokinetics it benefits us all.
• And, lest we forget, our industry is more productive, our products higher-quality, and our process control systems simply more effective because of the use of radiation and radioactivity that are used for process controls, to measure the levels of tanks, and so forth.

The bottom line is that our society is better for the use of radiation and radioactivity. We can live without them – but we would likely not live as long or as happily. Ironically, it seems that the public’s fears of radiation are proportional to our dependence on it as a society. Unfortunately, these fears can drive the public into actions that are unwise (such as forgoing the benefits of medical radiation), ill-informed (such as stocking up on iodized salt in the aftermath of the Fukushima accident), or that just make it harder and more expensive for society to garner the benefits of the radiation and radioactivity that benefits so many of us (such as excessive regulatory burdens). Will public education help? Can more information about radiation shine a metaphorical light for the public, helping them to see that their fears are largely groundless? As what we might call a “recovering professor” I’d like to think so, but that is a guess and not certainty.

Part of the reason for my lack of certainty goes to my second anecdote. Just as I played on my parents’ ignorance to manipulate them into leaving the lights on so that I could achieve my goal of reading past my bedtime, so too (I suspect) do some in the anti-nuclear movement take advantage of the public’s lack of understanding and the resulting radiation phobia to stoke the public’s fears in order to manipulate them into taking actions that they might otherwise avoid. The most recent example of this happened in the first weeks after the Fukushima accident when an anti-nuclear organization took a colorful graphic showing the propagation of the tsunami across the Pacific Ocean and labeled it “Pacific Dead Zone” and combined it with another graphic purporting to show four separate sites with “breached reactors” and yet another graphic indicating that, within 48 hours, the entire American west coast would be slammed with a radioactive plume exposing everyone to “75 rems” (0.75 Sv). Topping it all off, the author(s) of this graphic added the logo of the Nuclear Regulatory Commission (presumably to add legitimacy) and attached it to an article discussing all of the global horrors that were sure to ensue.

The author(s) of this graphic had to know that their work was a lie from beginning to end – that not a single bit of it had any legitimacy. And they knowingly used the NRC logo knowing they did not work for (and certainly did not speak for) the Commission. Yet they published it worldwide – it is still in circulation and has been attached to at least a half-dozen blatently anti-nuclear articles since the Fukushima accident. This is nothing more than a cynical exploitation of a tragedy designed to take advantage of public ignorance to push an agenda and those responsible should be taken to task. But the fact that this image continues to circulate also demonstrates the public’s relative ignorance when it comes to radiation and nuclear issues; I would like to think that a better-informed public would be more likely to see through such a sham.

Unfortunately, not much is being done to try to remedy the lack of public information that contributes so heavily to radiation phobia. I have talked with private and professional organizations – they have told me it’s the government’s job to educate the public on so sweeping and controversial a topic. I have spoken with news organizations – they have told me that public education isn’t news. I’ve also spoken with governmental agencies – they have told me that the government doesn’t want to frighten the public by bringing up radiation education in the absence of a real emergency. And those few organizations that are trying to do so are going about it passively – putting materials on-line and assuming that people will find them – instead of trying to find a way to push information into the public discussion.

I’m not sure what’s worse – not knowing how to start to address a recognized problem, or choosing not to take actions that you suspect will help. What I do know is that simply waiting and hoping that someone else will tackle a difficult – but necessary – task helps none of us while it serves society poorly.

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NOAA graphic of the recent coronal mass ejection headed towards Earth

Over the weekend Earth was slammed by the biggest solar storm in about a decade. Days earlier a huge x-class solar flare (the most powerful category) had blasted millions of tons of hydrogen into space, with Earth in the cross-hairs. The eruption – called a coronal mass ejection – blasted through space at more than a million miles an hour. The leading edge reached Earth on March 8 and the full strength hit Earth two days later, triggering a geomagnetic storm as well as triggering some concerns. But first a little about what happens during a solar storm and how it can affect the Earth, its inhabitants, and our society. By the way, NASA has some very nice information on solar flares and related phenomena on their heliophysics web page and the National Oceanographic and Atmosphere Administration maintains a space weather web page that nicely complements the NASA site.

Every so often – the frequency depends on solar activity, which varies over the course of the 11-year sunspot cycle – the Sun’s magnetic field twists and knots up and when the magnetic lines of force unkink (for lack of a better way to put it) the Sun burps, spraying hot gas into the interplanetary void. Most of these eruptions miss the Earth, at times we get blasted.

Much of the gas that hits us is in the form of a plasma – it’s ionized so we catch it in the form of electrons and protons with a smattering of neutrons and helium nuclei. These are also permeated with a magnetic field – when the gas reaches Earth it clams into the Earth’s magnetic field at speeds of hundreds of miles per second, compressing it towards our planet.

Normally our magnetic field does a good job of diverting charged particles away from the surface and into the van Allen radiation belts (although some charged particles always manage to funnel in along magnetic field lines at the north and south magnetic poles) but it can only do so much. A large cloud of gas from a powerful solar flare can overwhelm the Earth’s magnetic field, driving charged particles into the atmosphere to not only produce intense aurorae (the Northern and Southern lights) but also causing the magnetic field to flutter under the electromagnetic stress. Moving a magnetic field back and forth along an electrical conductor is pretty much the same thing that happens in an electrical generator – what matters is the relative motion of the magnetic field with respect to the conductor – and this motion can induce electrical currents in metals around the world. Electrical power lines, pipelines, rails, and the like can all experienced induced electrical current; this current in turn can harm satellites, can damage sensitive electronics (such as pipeline flow meters or electrical control equipment), can trip circuit breakers and overload electrical grids, and can even accelerate corrosion in pipelines that are affected.

All of this can be bad, but what gets the attention of many is the radiation dose from solar flares – all of these charged particles can make themselves felt not only in space but also on commercial airliners and even at sea level (for those who are interested you can calculate your in-flight radiation dose from galactic – not solar – cosmic rays through the FAA’s CARI software). Northern Arizona University professor Keran O’Brien, a highly respected scientist who specializes in solar and cosmic radiation, helped develop many of the calculations that went into the CARI software; using his work as well as studies of solar flares and flares on other sun-like stars we can calculate how frequently we might see high sea-level radiation doses from solar flares. It turns out that every few million years (give or take a little bit) there is a solar flare that will produce a sea-level radiation dose of about 100 rem (1 Sv) – enough to induce radiation sickness but not enough to kill an organism. Less powerful solar flares – with correspondingly lower radiation doses – are more frequent, but anything that produces a radiation dose of more than a rem happens so rarely that it is highly likely that nobody reading this will ever experience one. And neither will our children or grandchildren – such events happen only every few millennia. If – or when – we become a space-dwelling species our astronauts will have more to worry about; the solar flare that hit us recently would have been fatal to any astronaut outside the Earth’s magnetic field. But for those of us at ground level even powerful solar flares are more of an inconvenience than a direct health risk.

There has also been speculation as to the impact of solar flares that strike during one of Earth’s occasional magnetic field reversals. During these events the Earth is not totally bereft of magnetic protection, but the magnetic field is weaker and more chaotic. At present we might be heading into such a reversal – the magnetic field strength has dropped by about 10% over the last century or so – but this is still within the normal variability and geomagnetic scientists are not certain at the moment. In any event, geomagnetic reversals are frequent events (geologically speaking) that last only a few thousand years on average. The odds that a solar super-flare – something strong enough to cause short-term health problems – might hit during the relatively brief geomagnetic reversal are fairly slim. But even if the timing were to work out, a radiation dose of 100 rem (1 Sv) is hardly enough to kill anyone or to cause mass extinctions – that would take a dose of several hundred rem (several Sv).

The bottom line? Solar flares can cause problems with our increasingly-sensitive electrical and electronic infrastructure, but they are not likely to kill any of us directly. This doesn’t consider the long-term risk of getting cancer from the elevated radiation dose rates, but I’ve devoted a lot of space to cancer risks in earlier blogs and will not revisit them here. So for me – I keep flying (you’ve got to love those little bags of peanuts!), I’m continuing to live in mid-latitudes, and I’m not looking for insurance policies with solar flare coverage. But preparing for a blackout? Always a good idea!

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It is a shame that the world’s focus remains on the reactor plant accidents and the perils of nuclear energy – in spite of the fact that nearly 20,000 were killed or remain missing because the earthquake and tsunami while the radiation from the reactor accidents have yet to claim a life (there have been five fatalities among workers, none of which are radiation-related). From the start the world has focused on the least of the problem facing Japan, leaving the Japanese to find and bury their dead, find homes for those who lost everything, and rebuild tsunami-ravaged cities.

I spent 10 days in Japan last April, part of a small team that visited Sendai and Fukushima (along with Soma, Minimasoma, and Iidate – all of which were also hit hard by the events of March 11; when we landed at the Sendai airport we could see the water damage and we were all moved to tears when we saw how entire neighborhoods had simply vanished. Seeing the damage ourselves, smelling the mud and the decay, visiting the evacuation shelters, and meeting so many people whose lives had been upended – being there in person after having watched the news coverage was like standing on the rim of the Grand Canyon after seeing a photo spread in National Geographic. As a good health physicist I took radiation measurements in addition to wearing my trusty dosimeter (a Mirion Technologies InstaDose badge, for those of you who might be interested) – I picked up more radiation on the flights to and from Japan than I did in our time on the ground in the vicinity of Fukushima and nowhere did I see any radiation doses that were dangerous. Having said this I have to acknowledge that we only visited a few locations, all of which were outside the 20-km radius that was evacuated. But the fact is that radiation from the reactor accident hasn’t killed anyone and is not likely to do so in the future – a fact that is easily overlooked by those of us watching the continuing news coverage.

I am not trying to downplay the severity of the reactor accidents – three reactors melted down and a huge amount of radioactivity was released into the environment. This is the second-worst reactor accident in history – and it has yet to cause a single radiation-related fatality in the year since the accident (the longer-term toll is yet to be determined, although given the relatively low doses to which people have been exposed there are not likely to be many – if any – long-term cancer deaths from the radiation either). Over three hundred thousand people have been evacuated from the contaminated areas, contaminated livestock have been slaughtered, contamination showed up in the Tokyo drinking water – and there hasn’t yet been a single fatality from radiation. This bears repeating: for all the severity of this accident – for all of its impact on Japanese society and on the world’s views of nuclear energy – there has not been a single radiation-related fatality from this accident.

One other thing bears mention – it is likely that the Japanese weathered the reactor accident far better than would have we Americans. The shelters we visited, for example, were still clean and orderly. Items set out to be taken and used on the honor system were taken sparingly and returned after being used. Most of the people being sheltered were (of course) unhappy, but they followed the shelter’s rules and they did their share to keep the shelters running effectively.

So with the perspective of a year’s time, what have we learned – what can we reflect upon – as the first anniversary of this tragedy approaches?

• One thing we have recognized is that anyone – including governments – can make knee-jerk reactions. Germany and Switzerland both announced early on that they were shutting down their nuclear reactors and Japan announced its determination to add new capacity in the form of alternative energy sources.
• We have seen that radiation phobia is as potent as ever. In spite of the utter lack of evidence of adverse health effects in Japan there are those claiming the existence of deaths in the United States and awaiting a flurry of deaths among those exposed in nearby cities.
• It appears as though public knowledge of radiation and its effects leaves much to be desired. Fears in Asia, the United States, Japan, and Europe are all exaggerated compared to the actual threat and there are still many who are worried about what fate might befall them from exposure to this radiation.
• This fear is largely due to a woeful lack of understanding on the part of the public and this lack of understanding is the fault of governments, who fail to provide their citizens with the knowledge they need to make informed decisions when it comes to radiation. Absent actual knowledge, citizens are going to make decisions based on misinformation, lack of information, and their resulting fears.
• We have been reminded that “sexy” stories trump all else – otherwise we would be hearing news stories about the recovery from tsunami damage, rebuilding infrastructure destroyed by the natural disasters, energy conservation measures required by the loss of the nuclear reactors, and the like.

The reactor accident warranted global attention, just as the accidents at Three Mile Island and Chernobyl warranted global attention. But this attention was appropriate only in a world experiencing “typical” tragedies – the earthquake and tsunami were utterly devastating and caused far more damage, death, and destruction than the reactor meltdowns. In a just world the reactor accidents would have been recognized as significant accidents that paled in comparison to the natural tragedy that unfolded. In an adequately informed world the world’s attention would have focused on the homeless, the lost, and the dead – not on an accident that placed nobody at risk. And in such a world we would recognize that nuclear energy takes a lower toll on human health and on the environment than does the continuing use of fossil fuels. It is a shame that, because of our lack of understanding and our fears, we have taken our eye off the ball – that we have concentrated on the least deadly part of the tragedies that unfolded on March 11, 2011. Certainly we must be careful with both radiation and nuclear energy – but we must give them only the respect and the attention they are due; to do otherwise is to shortchange those who need our help the most.

One final note: While the earthquake and tsunami affected a huge swath of Japan, Soma City was particularly hit – over 40 children were orphaned, several of them the children of firefighters who lost their lives while helping their fellow citizens reach safety. The word “hero” is often overused but I doubt that anyone can argue that a person who knowingly heads towards danger to save others is a hero. During our visit, Soma City Mayor Hidekiyo Tachiya told us of a fund he has established to help support the children orphaned on March 11, 2011 and to help send them to college when the time comes. I have donated to this fund and I would urge you to support these children if your circumstances permit.

The post Fukushima: A Year Later appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Now think a little further – infectious disease is an equal opportunity killer that hits the young as well as old, while heart disease and cancer tend to strike later in life. Reducing deaths among younger people lets more of us live into our cancer- and heart-disease-prone years, so of course these will begin to take a greater toll. As public health and medicine (not to mention other safety measures that reduce accidental deaths) lengthen our lives we should expect to see more people succumbing to things like cancer and heart disease – and whenever we think about reasons for increases in these diseases of our later years we have to try to untangle the impact of longer lives from the impact of whatever possible we’re considering. This isn’t to say that our lifestyles, eating habits, and environment play no part in the rising numbers of death due to cancer and heart disease, just that we have to be able to disentangle the effects of a longer lifespan from the effect of whatever cause(s) we are examining.

This came to me as a sort of epiphany when I was in Cambodia several years ago  on a radiation safety mission – I was visiting Cambodia’s sole radiation oncology clinic. I asked the facility’s sole medical physicist why there was only one clinic, expecting him to talk about governmental instability or poverty. Instead he pointed out that the average Cambodian didn’t live long enough to get cancer – with a median lifespan of less than 50 years most Cambodians died of malnutrition, injuries from landmines, disease, and simple poverty. He went on to say that he’d consider it a triumph to have to open a second clinic because it would mean that more Cambodians were living long enough to get cancer.

Interestingly, in spite of huge increases in human exposure to synthetic chemicals, electromagnetic fields, cell phone radiation, food additives, ionizing radiation, and so forth, statistics maintained by the American government clearly show that the age-adjusted cancer incidence has been dropping fairly steadily for nearly a century. Of course, this doesn’t mean that none of these things causes cancer; simply that whatever impact they have (at the levels to which most of us are exposed) is likely lower than the gains we derive coupled with improved screening and treatment. As one example, the radiation from x-rays might be carcinogenic (although at these very low levels of radiation exposure it’s almost impossible to say one way or the other), but we also derive a huge amount of good from being able to properly diagnose injuries and disease with these x-rays. Thus, medical x-rays on the whole are likely to extend life more than to cut it short because they can catch things that are immediately dangerous while adding only very slightly (if at all) to the risk of developing cancer in another few decades.

We should also keep in mind that, even though the incidence of cancer is dropping, the total number of people who get cancer has been steadily rising. Part of the reason for this is that the population of the US keeps growing – even a slightly decreasing cancer rate can lead to more cancer cases if the population grows more rapidly than the cancer rate drops (for example: say that 30% of the people in a city of a million people develop cancer so that 300,000 people develop cancer in their lifetimes – if the cancer rate shrinks to 20% while the population grows to 2 million then there will be 400,000 people who get cancer). Paradoxically, a reduced cancer rate can still lead to more total cancers if the population size increases rapidly enough.

Something else to throw into the mix is adjusting for age – cancer is more likely to be an affliction of an older population so as a population ages it is also more likely to develop cancer (as I saw in Cambodia). So to get a fuller picture of what’s going on it’s only fair to compare the cancer rates in each age bracket – instead of looking at gross numbers, or even overall rates, of cancer incidence it’s better to compare people of similar age. So we look to see how cancer rates among, say, 80 year-olds changes from year to year, along with cancer rates among those in their 70s and so forth – this is the age-adjusted cancer rate. And as noted above, what we find is that the age-adjusted cancer incidence (with the exception of smoking-related cancers) has been dropping steadily for nearly a century.

What this all means is hard to say – I’m not an epidemiologist and I don’t want to jump to unwarranted conclusions. But it at least suggests that many of the things we are concerned about (electromagnetic fields, radiofrequency radiation, cell phones, the level of radiation found in medical x-rays, and so forth) – things to which our exposure has skyrocketed over the last several decades without a concomitant increase in cancer rates – might not be as bad as we fear. Speaking about the health and environmental impact of radiation and its variability radiation biologist Antone Brooks made a comment about ionizing radiation – that whatever the effect is at low levels of exposure “it’s not a big player.” When exposure to medical radiation and electromagnetic fields have increased by a factor of thousands while cancer rates have dropped it is reasonable to ask if our concerns might outstrip the data.

The post What we can learn from cancer statistics appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Of course there’s more to making a nuclear reactor than simply putting a bunch of uranium together – there also has to be a way to slow down neutrons to energies that are more likely to cause fission (a process called moderation). But in at least one location there was a wonderful confluence of events – uranium precipitated out of solution in a mass of sandstone; when the porous rock became saturated with water, conditions were right, and nuclear fission ensued. For over 100,000 years the uranium deposit happily fissioned away off and on with the reactor shutting down when the heat from fission boiled away the water and then restarting when the rocks cooled to the point where water could re-saturate the rocks.

Fast-forwarding a few billion years – to 1972 – French scientists noticed that uranium from a particular mine in the Oklo region of the African nation of Gabon had a different isotopic makeup than any other uranium ore on Earth, being depleted in U-235. After some great scientific detective work they realized that the only plausible explanation for the discrepancies they found was that this ore body had undergone fission – that the Earth had once had a natural nuclear reactor. Since that time studies have continued – there have been tons of findings but, to me, there are three that are particularly intriguing (in addition to the obvious one that nature beat us to the punch in this particular development):

• The type of rock formation in which the Oklo reactor was found is hardly unique
  • The Oklo reactor formed in a sandstone deposit saturated with water in a geologic formation called a sedimentary basin. This kind of rock formation has been fairly common on Earth throughout its history – what is unusual is its preservation for so long a period of time. According to geologists Laurence Coogan and Jay Cullen (both of the University of Victoria) there might have been a fairly large number of such reactors at that point in Earth’s history. It could be that the Earth of a few billion years ago was filled with bubbling and steaming reactor zones, pumping radiation into the nearby environment. Not only that, but there has even been speculation that the same thing might have happened on Mars in the distant past. Pretty much anyplace where enough uranium with reactor-level concentrations of U-235 could collect and be immersed in water could have supported a fission chain reaction – on Earth, on Mars, or anywhere else in the universe.
  • Virtually all of the fission products are still in place in the rocks that once hosted the reactor
    • Uranium fission produces radioactive waste, whether the fission takes place in a natural or an artificial nuclear reactor. Surprisingly, Australian geologists J.R. de Laiter, K.J.R. Rosman, and C.L. Smith found that virtually all of the radioactive waste produced by the Oklo reactors can be accounted for. What makes this remarkable is that this radioactive waste has been sitting in porous rock that has been saturated with water for two billion years – and it’s still largely in place. This bodes well for our trying to isolate radioactive waste for a mere hundred thousand or million years in a specially designed repository dug into much less permeable rock that is only occasionally waterlogged.
    • And some have speculated that natural reactors might have affected the evolution of ancient life.
      • Coogan and Cullen also point out in their paper that radiation from ancient reactors might have had both positive and deleterious effects on nearby living organisms. The negative impact is easy to guess at – periodic blasts of high-level radiation could certainly kill all but the most radiation-resistant organisms. On the other hand, radiation dose rate drops off quickly with distance and shielding – move just a few meters from a location with deadly radiation levels and you can find yourself in an area that is easily survivable. It is entirely possible that radiation from early natural nuclear reactors not only killed whatever migrated closest, but that it also might have induced mutations in slightly more-distant organisms, accelerating the rate of evolution.

The Oklo reactor may or may not have been unique but, regardless, it is fascinating. And if it turns out to have lessons that can help us better understand the evolution of life or the disposition of radioactive waste then so much the better.

The post Lessons from Oklo appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Part of the problem is that there seems to be no universal definition of the term. One website (Jargon Database) defines an existential threat as “a military or terrorist threat to the existence of something, usually the United States. Usually involves nuclear, chemical, or biological weapons” while Wikipedia does not define the term itself, but uses the term when describing events (supervolcanoes, asteroids, etc.) that could threaten “to destroy, or drastically restrict, human civilization; could cause human extinction.” Other definitions take a somewhat broader view that includes not just threats to a nation’s existence but also threats to a nation’s government or to its national character. Agreement of what constitutes an existential threat, then, seems to hinge on agreeing what is actually being threatened.

As recently as last month we have heard, too, that cyberterrorism might pose an existential threat with the FBI defending this statement by noting that hacking could “eliminate whole companies” and “could actually cause death.” In all honesty, to me this is really stretching the use of this term – I don’t doubt that a hacker could put a company out of business (thus posing a threat to that company’s existence) and could cause serious mischief and harm, but is this really a threat to our nation? Is it appropriate to use the same term for a corporate threat, a threat to a nation’s existence, and an event that threatens to push humanity into extinction, or is this a gross misuse of the term – hyperbole that might help to raise the profile of hacking on a corporate level, but that also detracts from the seriousness of the term and the concept it represents? Do we risk devaluing the term by applying it too broadly?  It brings to mind the scene from Steve Martin’s movie Roxanne in which the main character bemoans the overuse of the word “love” by asking “How can you love a floor wax? How can you love a diaper? How can I use the same word about you that is used about a stuffing?” Since there is no consensus on what an existential threat even is, how can anyone hope to agree on what poses an existential threat? And, lacking this agreement, can we even have a reasoned discussion about this topic?

So – for the rest of this posting I’d like to narrow the focus of what might be meant by the term “existential threat” to look at some of the more serious outcomes: an event that threatens a nation’s existence as a part of the family of nations and an event that poses so great a threat to a nation’s character that it would no longer be recognizable. We saw examples of the former at the end of the Cold War, which saw the nation of Yugoslavia break up into its component pieces – Yugoslavia vanished from the map and was replaced by its component parts (just as Czechoslovakia broke into Slovakia and the Czech Republic, and the former Soviet Union disintegrated into over a dozen nations). The United States faced an existential threat during the Cold War, when we worried about nuclear annihilation or conquest by the Communist world, just as Israel faced an existential threat in the attacks that followed its declaration of statehood. Examples of the latter could include the rise of communism in the formerly free nations of Eastern Europe, which completely changed the character of so many nations by turning friends and family members into possible informants and enemies; the rise of the Khmer Rouge and its perversion of Cambodian society; or the rise of totalitarian dictatorships elsewhere in the world that turned daily life upside down for the ordinary citizens of a nation.

Using the first definition of “existential threat” makes it hard to see how al Qaeda or any other terrorist group – even one armed with nuclear weapons – can pose a threat to the very existence of the United States, or to most other of the world’s nations. In this discussion I want to make it very clear that I am not trying to downplay the suffering and death such an attack would cause – I am only asking if such an attack would threaten a nation’s existence. I should also make it clear that I am not talking about the concept of a “winnable” nuclear war in which tens or hundreds of nuclear weapons might be unleashed – I am talking about a terrorist attack against a small number of cities. So with these caveats in place, does nuclear terrorism pose an existential threat to a nation?

I would argue “probably not” and I would use as my evidence the nation of Japan. I visited the Atomic Bomb Museum in Hiroshima a little over a decade ago and I think it is impossible to come away from the museum with anything other than horror at what nuclear weapons can accomplish. But the fact is that the nation of Japan survived the nuclear destruction of two of its cities and the equally devastating fire-bombing of others with both its status as a nation intact along with its national character. I would argue that Japan’s survival as a nation and as a people strongly suggests that nuclear terrorism – however terrible a cost it would inflict on a society so attacked – is not likely to pose a threat to that society’s very existence. I would further argue that, unless such an attack were so demoralizing as to cause a people to doubt their very society, its values and principles, its form of government, and its right to continue to exist, even a nuclear terrorist attack is similarly unlikely to pose an existential threat to the idea that a people have a right to exist as a nation.

Having said that, I agree that a nuclear attack – or any devastating terrorist attack – has the potential to change the character of a society and that, in this sense, it can pose an existential threat of the second sort. Consider, for example, some of the changes we have seen in the United States since the September 11 attacks. First, as before, let me qualify what I am about to say by noting that I do not intend to argue whether or not these changes are justified, whether they are for the better or for the worse, or about their morality. But that there have been changes is undeniable:

• Detaining suspects in secret overseas holding facilities, often without documented cause
• Staging unannounced military actions and raids on the soil of allied nations
• Advocating torture as a national policy
• Greatly increasing opportunities for surveillance and scrutiny of both citizens and non-citizens
• Marking American citizens for assassination instead of arrest and trial
• Accepting government scrutiny with remarkably little outcry
• Accepting the politicization of the judicial system (including the Supreme Court) with remarkably little debate
• Accepting increasing societal inequality
• Accepting explicit governmental support of faith-based organizations
• Permitting military operations on American soil on a routine basis

I could go on, but the net result is that, in our concerns about the risk of terrorist attack, we have accepted a huge number of changes that go far beyond what we found necessary during the Second World War or, indeed, during any other war.  Our national character has changed – as a nation we seem less concerned with individual freedoms and more concerned for individual safety and security, less concerned with striving for relative equality across society and more concerned with cementing into place the relative advantage of whatever group with which we identify. As a whole, the nation has become more conservative and much of this seems to have come about as we worry about the threat of terrorism.

So the question is whether or not terrorism poses an existential threat to our sense of national identity and to our national character? Are the substantial changes we have already undergone likely to continue and to push us into a form of government and society that would make our nation unrecognizable? Or is the character of the American people so strongly engrained that we might lurch from left to right and back again before regaining our equilibrium? I don’t know the answer to that, but I am encouraged by the fact that Americans seem to have a remarkable talent for recognizing and correcting our political and societal excesses – as a nation we seem to be fairly resilient.

So to put all of this together….

For a small nation – perhaps a nation with only one or two major cities into which most of its people and infrastructure are crammed – I can see that a devastating terrorist attack can pose a threat to that nation’s very existence. But having said that, there are not many nations on Earth that are so small – and most of them are probably not likely to be attacked in any event – that this seems a plausible risk. Thus, most forms of terrorism would seem unlikely to pose the first sort of existential risk to most nations on the planet.

On the other hand, it is easier to see how a series of attacks could push a nation to abandon or to move substantially away from the core values that once defined it. Thus, no matter how resilient a nation might be, it seems plausible to conclude that terrorism might prove an existential threat of the second sort – we can only hope that the nations most subjected to terrorism will remain resilient enough to resist the temptation to change the values they hold most dear.

The post Existential threats appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Iranian leader Ahmadinejad inspecting a uranium enrichment facility

There has been a lot of debate recently about the continually putative Iranian nuclear weapons program. This obviously poses a risk and it seems at least plausible to assume that developing nuclear weapons is an Iranian goal. But we still have to be careful about the claims that are being made to make sure that we understand the severity of the situation, and I’m not sure that some of the stories being bandied about are entirely accurate. Here are a few things that bear consideration:

On February 2 an Israeli general (Aviv Kochavi) asserted that “International intelligence agencies are in agreement with Israel that Iran has close to 100 kilograms (220 pounds) of uranium enriched to 20 percent, which is enough to produce four bombs.” This is misleading at best. A hundred kilograms of uranium enriched to 20% U-235 will have about 20 kg of U-235. But a fissionable mass of 94% pure U-235 weighs about 16 kg so Iran might have enough uranium with further enrichment to the weapons-grade level to make a single nuclear weapon – maybe two – but certainly not four.

There have been a number of stories about possible American or Israeli attacks against Iran’s nuclear infrastructure (here is one of them) in response to any of a number of possible provocations. The problem is that Iran has a widely dispersed nuclear infrastructure and some of their facilities are in populated areas. Israel’s 1981 attack against Iraq’s Osirak reactor caused a serious setback to Iraq’s nuclear weapons program because Iraq had a very limited nuclear infrastructure that was fairly easy to take out – if Iraq had been pursuing a plutonium-based nuclear weapons program then this attack undoubtedly set back these efforts by several years. But Iraq had a very limited nuclear weapons program in 1981 – a single attack against a single target could do significant damage. This is not the case in Iran – Iran has so many installations in so many locations (some of them in heavily populated areas) that anything short of all-out war is unlikely to have any lasting impact. Unless a nation is willing to either visit utter devastation upon Iran, to occupy the nation, to spark a successful insurrection against the current government, or to attack targets located in the midst of large civilian populations then it must assume that an attack against Iran’s nuclear facilities will be at best a stumbling block. At worst, an unsuccessful attack might even spur Iran on to greater efforts under the assumption that presenting the world with a fait accompli will deter any future military action.

There have also been a number of people stating that an Iranian nuclear weapons program poses an existential threat to Israel. But an “existential threat” is something that threatens a nation’s very existence. But is this really the case? I agree that any nuclear attack against any nation would be devastating and terrible and I know that a single nuclear weapon detonated anywhere in Israel would affect a huge number of people. But I’m not sure that I agree that a single – even a double – nuclear weapon detonation would wipe Israel from the map or would cause it to vanish from the family of nations. It is entirely plausible to believe that Iran understands that there would be overwhelming retaliation in the event of a nuclear attack against Israel and that this threat alone will deter Iran from using the nuclear weapons it might develop against Israel. This is not to say that a nuclear attack against Jerusalem or Tel Aviv would not be a huge and terrible blow – rather, to point out that the radius of destruction of a nuclear weapon is far smaller than the size of Israel. Should Iran choose to use a nuclear weapon against Israel there would be untold damage and suffering – but it is not likely that such an attack would remove the state of Israel from the map.

I do not want to minimize the threat of an Iranian nuclear weapon, to suggest that an Iranian nuclear weapon would be acceptable, or to appear blasé about the consequences of using such a weapon against Israel. But I do want to suggest we think clearly about this topic. We cannot make good decisions unless we can accurately assess the threats (and our allies) face or the potential consequences of the actions of all parties.

The post A quick note about Iranian nuclear weapons…. appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

From the high-energy collision of two gold atoms

A few months ago the Center for European Nuclear Research (which goes by the acronym CERN) reported it had found evidence of the most-wanted subatomic particle – the Higgs Boson (aka the God particle). If this finding is confirmed it will wrap up one of the longest-standing loose ends in our current model (the Standard Model) of particle physics. In fact, the Large Hadron Collider was constructed at CERN pretty much specifically to look for the Higgs particle – one of the most expensive scientific instruments ever built. So it is understandable to wonder what it is about the Higgs that warrants such effort and expense – and whether or not it’s worth it. One place to start is with what the Higgs particle is and why we even care about it.

One of the biggest questions in physics is why anything has mass at all, and why things have the mass that they do. Photons, for example, are massless, protons have a mass of a tad more than one atomic mass unit, and electrons are about one-two-thousandth the mass of a proton. When you add up the masses of all of the protons (and electrons and neutrons) in our bodies you get the mass of a person. But what isn’t explained by the Standard Model is why a proton weighs one amu and not half (or double) that amount. This is where the Higgs comes in.

In 1964 Scottish physicist Peter Higgs proposed that a particle with some very specific properties could account for this. Specifically, Higgs proposed that the Higgs particle (and its accompanying field) permeates the universe and it interacts with all of the other particles in creation. Think of trying to pull a piece of plywood through water – it can cut through the water edgewise with very little resistance or it can be pulled through broadside at great effort. Edgewise the plywood hardly interacts with the water at all – the equivalent of a particle like the electron that barely interacts with the Higgs field and that has little to no mass. That’s the theory anyhow, but until the Higgs can be found, identified, and studied we don’t know if the universe matches up with the theory.

OK, so in the next few years we might know a little more about how the universe works, but is it really worth a decade’s work and $9 billion just to figure this out, especially when there are poor and hungry people in the world and in times with so many financial and economic problems? Is it really worth it or is the Higgs particle and all of the other abstract knowledge just a luxury that we cannot afford?

The problem with abstract knowledge is that we never know when it will become useful. The galvanic effect was discovered in the late 18^th century and it led to the invention of batteries, but there was nothing for the batteries to power for more than a century – twitching frog legs and stored electrical charge were good for laboratory demonstrations and not much else for decades. For that matter, electricity was named by the Ancient Greeks but it, too, was not put to any real use for a few millennia. When the laser was first developed it was called “a solution in search of a problem” – it was an answer to a decades-old speculation and little more. These one-time curiosities are today part of our scientific and intellectual infrastructure – part of the foundation upon which much of our technology and our society rest. And had the scientists who made these discoveries – and so many others – been dissuaded by thoughts that their work might never be used to make the world a better place, had they been dissuaded by thoughts of cost-benefit analysis or the lack of immediate return on their investment of time and money then we might not today have the technology and the standard of living it has brought with it. And it is safe to say that those who discovered electricity, batteries, the electron, and lasers never conceived of the technology that their discoveries would one day unlock.

So one way to look at the CERN accelerators and the particles they will find is as a form of intellectual insurance policy – an investment in our intellectual future that might someday help to spark whatever the next level of technology and discoveries there might be. This sounds good with regards to physics research as well as biology and chemistry and some of the other sciences that we know can give rise to practical applications. But is this the only reason to try to understand the universe, or does knowledge have an intrinsic value in and of itself?

This is a question that I cannot pretend to be objective about – I have been a scientist for a number of years and I firmly believe that the pursuit of knowledge for its own sake is an important endeavor. If we look at the history of humanity we see a constant curiosity and a continual search for knowledge – this curiosity is part of what led us to explore and populate the Earth and is what keeps us pushing to explore and learn what we can about the world and the universe around us. Part of what defines us as a species is our continual quest to learn what’s on the other side of a mountain range or beyond the horizon – as we have explored our planet and filled in the blank spots on the maps we have been increasing sublimating our innate curiosity by extending our quest into realms that our bodies can’t enter – the depths of the universe and the infinitesimally small reaches opened up by our experiments in high-energy physics.

This exploration has often been expensive and the cost keeps increasing. In the realm of physics, we can detect alpha particles, electrons, and neutrons in nature and need only buy (or make) the instruments to detect them – this level of physics can be accessed for only a few thousand dollars. Identifying protons and doing the next level of physics requires more – for millions of dollars we can produce artificial radionuclides and can split (or fuse) atoms. But to go further – to produce (and identify) the subatomic particles that help us to really start to understand how the universe is put together takes devices that cost hundreds of millions or even billions of dollars. On the other hand, the cost of expanding our physical horizons is high as well – space probes, huge telescopes, and manned space travel are about as expensive as high-energy physics. The question is what is more expensive – basic research that may have no utility, or deciding to learn no more. The Higgs boson – and whatever comes next – may or may not one day turn out to have a use. But we know that nothing will ever come of failing to look.

The post Who gives a fig for the Higgs? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The radium kit found in PA

My Great-Uncle Harvey was the only physician I knew as a kid. He delivered my father, my aunt, me, and my sister; he visited me in the hospital when I had my tonsils out; gave us our shots; and attended to all of the other minutiae of keeping us all healthy. In fact, it wasn’t until I joined the Navy that I finally understood why most of my classmates had never enjoyed going to the doctor (the dentist as well – my grandfather and uncle were my dentists until I joined the Navy). What makes this family history relevant is that my great-uncle began practicing medicine in the 1920s and he used to use radium in his medical practice.

From today’s perspective, it’s hard to understand how enraptured people were with radium a century ago. Not only was radium used to treat cancer, but radium-bearing potions were drunk to improve one’s overall health and radium was even applied in plasters to help treat medical conditions that were intractable to other remedies. Radium was used for all sorts of glow-in-the-dark products, including watch dials and even fishing tackle. With today’s hyper-sensitivity to radiation this is hard to believe – but one of the reasons for today’s hypersensitivity to radiation might actually have something to do with the profligacy of earlier decades.

Consider first the miracle that radium must have seemed to the physicians of my great-uncle’s era. Being able to burn out a cancer (instead of facing the risks of surgery) must have seemed miraculous and it was only natural to wonder what else radium could treat. Add to this the fact that the prompt effects of radiation exposure (burns, for example) manifest and often resolve themselves over the course of a few weeks or months, while the long-term effects (cancer) take up to a few decades to appear – for the first 20-30 years it likely seemed that the use of radiation in medicine was all benefit with no long-term downside. Radium had to have seemed miraculous to my great-uncle and his colleagues. This early work grew into today’s radiation oncology and nuclear medicine, but there is also no denying that much of the early inquiries into the use of radiation in medicine ended up causing harm directly (in cases of people injured or made ill by their treatments) or indirectly (when these treatments inspired the use of radium in later patent medicines).

In the post-World War II years the growing field of nuclear science began producing all sorts of other nuclides, including many that were better-suited than radium to addressing the needs of both medicine and industry. The use of radium went into decline and for the last 20 years the emphasis has been on finding and disposing of the radium that had been used – with a half-life of 1600 years we can’t just wait for it to decay away. These radium round-ups have met with a great deal of success, but there was a lot of radium produced and it is far from being accounted for yet. Military gear – compasses, watches, instrument dials, and the like that people have collected – the locations of former medical and industrial facilities, occasional medical sources that were left behind in basements or storage lockers, and the soil beneath many of these facilities; all of these keep coming to light year after year.

One such case – and the one that prompted this posting – came to light just a few weeks ago when an antique medical kit containing almost a gram of radium was found in the trash in Norristown PA (for those who are interested in more details there is a posting on the Pennsylvania Bureau of Radiation Protection web page that gives a short description of the incident). Radium hasn’t been widely used in decades – in the words of health physicist Joel Lubenau, “Who would have thought we’d be dealing with a gram of radium in the 21^st century?”

Coming on the heels of the radioactive tissue box holders this could be taken to suggest that we have lost all control of radioactive materials. But I’m not sure I am willing to go that far.

One thing to keep in mind is that there’s a big difference between these two incidents. The cobalt-60 source that ended up in a batch of molten steel in India represents a breakdown in regulatory control – a radioactive source that should have been accounted for. But as health physicist Jim Yusko points out, most radioactive materials were not regulated at all until the passage of the Atomic Energy Act in 1954 – the radium in this kit (like the radium my Uncle Harvey used) was never licensed. In fact, prescription drugs today are better-controlled than were the medical radionuclides of the Radium Age. So this kit’s turning up doesn’t represent a breakdown in regulatory controls so much as the unearthing of a legacy of medicine’s past infatuation with radium.

One final comment seems in order. It matters from a societal standpoint that this radium kit was never under regulatory control because it means that, in this case, the system did not break down. But from a health standpoint it doesn’t matter where the radioactivity came from – radiation is radiation and it affects our bodies the same no matter where it comes from. Properly handled, the radioactivity in kits such as the one found in Pennsylvania poses no risk – but not many are trained to handle radioactive materials properly. If you happen to find something like this yourself it’s a good idea to treat the radioactive materials with respect, to call the regulatory authorities right away, and to do your best to keep the materials secured (put them in a locked storage room or shed, for example) until someone else comes to take responsibility for it.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety

The post The radium age appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Chuck Surre surveys radioactive waste at the University of Rochester

I am a health physicist. And no, this is not the first admission in a 12-step program – more like a statement that means very little to most of the people in the US. If I tell the person next to me on a plane, for example, that I am a health physicist they usually look blank or they start telling me about their bad back (or one guy who started talking about his prostate on a flight from Amsterdam to Detroit – but that’s another story). Part of the reason for this is that the name “health physics” came from the secrecy of the Manhattan Project – an effort to learn about radiation’s health effects without cluing Nazi Germany in to the fact that we were developing nuclear weapons. And the true measure of the success of this effort deception is that today – 70 years later – almost nobody knows what a health physicist does (for the record, health physics is the profession that deals with radiation safety for people and the environment).

This relative obscurity is not necessarily a bad thing, but it does mean that very few kids tell people “I want to be a health physicist when I grow up.” In fact, most health physicists fell into their profession by accident – they may have started in biology, physics, chemistry, even geology or astronomy and just happened to wind up doing radiation safety. The upshot is that this brings up two potentially significant problems – there is a shortage of health physicists in the United States and the majority of those running radiation safety programs are not trained radiation safety professionals. Let’s look at the first issue first, starting with what it is that health physicists actually do.

For a relatively small profession (there are about 6000 people in the Health Physics Society) the profession has a hugely broad reach. Health physicists are in hospitals where they help to make sure that the radiation and radioactivity used in the practice of medicine are used safely, responsibly, and in accordance with regulatory requirements. Nuclear medicine, radiation oncology, radiology, nuclear cardiology – all of these departments make heavy use of health physicists for routine radiation safety (including handling the radioactive waste that nuclear medicine patients produce). Health physicists also work at the nuclear reactors and particle accelerators that produce the isotopes used in medicine or for research. Health physicists also run radiation safety programs at large research universities as well as in industrial R&D facilities. Radioactivity is used in the military (not only naval nuclear reactors, but also in many other military applications), in the nuclear power plants that produce about 20% of our energy, and in a host of other parts of society. And not only is health physics practiced in all of these areas, but we also depend on health physicists to regulate radiation safety across the nation – the Nuclear Regulatory Commission, the Environmental Protection Agency, other federal agencies, along with over 30 state radiation safety programs all make use of health physicists to inspect and oversee radiation safety programs nationwide.

Right now there is a nationwide shortage of health physicists. This is not just my observation – although I can vouch that it is not easy to fill open HP positions – it is also the observation of the Health Physics Society in the “Human Capital Crisis Task Force Report” that was completed in 2004. The HPS identified a large – and growing – shortfall in health physicists across the board but noted that the shortage is particularly ominous in the regulatory sphere (more on that in a moment). And there are a bunch of reasons for it, starting with what I mentioned in the first paragraph – it’s hard to attract high school and college students into a field that nobody’s heard of. This is one of the reasons that, even as the HP shortage grows (and as salaries grow to reflect the scarcity), university HP degree programs are not only graduating fewer students but are even closing their doors.

Another factor is that a huge number of health physicists entered the profession in the 1950s and 1960s as participants in a huge fellowship program aimed at educating health physicists for the nation’s growing nuclear weapons and nuclear energy programs – the Atomic Energy Commission (AEC) fellowship program established world-class health physics and radiation science programs in universities around the United States and these programs graduated the people who built our profession and who have been its leaders for the last half-century. But the AEC Fellows have been retiring for nearly a decade now, leaving massive holes in our profession and without adequate replacements in the pipeline. I’d like to start by looking at the impact of this shortage among our regulators and then to look at how it has affected (and will likely continue to affect) the industries that rely on radiation and radioactivity.

Many years ago when I worked for a state radiation regulatory program I used to get into congenial arguments with, of all people, my favorite hotdog vendor – a staunch Libertarian. He would accuse me of taking the public’s money for my job when we should just be able to rely on market forces to weed out businesses that were making their employees (or their customers) sick. Without getting into the whole debate over the appropriate size (or role) of government, I realized that we simply cannot expect the general public to know enough about radiation for market forces to have a chance of working – in some fields there just is no substitute for regulatory oversight by knowledgeable professionals. We have been losing these knowledgeable professionals in state, local, and national oversight agencies for years and the bleeding shows no sign of stopping anytime soon.

Not only that, but when the regulators have to compete with private industry for a scanty supply of new graduates – especially in an era of budget cuts and fiscal hardship – governments don’t have many options; they can try to entice people to extend their service, they can try to offer higher salaries, or they can accept the fact that many of their new hires might require years of training to become effective. In fact, this view was shared by the Government Accountability Office when it noted that the growing shortage of health physicists in regulatory circles could have a serious impact on nuclear reactor safety and on radioactive source safety and security in the United States. Today – when new reactor plants are on the drawing board, when we have an ever-increasing reliance on radiation in medicine, and in the aftermath of the Fukushima accident and the more recent losses of radioactive materials in the US and abroad – it would seem we can scarce afford to scale back on effective radiation and nuclear safety oversight.

There is another impact of this HP shortage as well – an increasing number of companies are turning their corporate radiation safety over to people who are not radiation safety professionals. Many hospitals and medical clinics place their radiation safety in the hands of a physician or medical technologist while a huge number of corporate licensees use multi-tasking industrial hygienists, safety professionals, engineers, or technicians as Radiation Safety Officers. Nationwide there are over 20,000 radioactive materials licensees – not to mention tens of thousands more facilities that use radiation-generating equipment such as x-ray machines and linear accelerators – and there are few than 10,000 radiation safety professionals in the United States. I spent about a decade teaching radiation safety courses for prospective radiation safety officers – my typical student was the person who ran the slowest when the need for a new RSO arose. The fact is that the overwhelming majority of radiation safety in the United States is administered by people who do not consider themselves to be radiation safety professionals – they are just stuck with the job.

Having said this, I have to admit that not every licensee needs a professional health physicist. Some radioactive sources are small and innocuous – it doesn’t make sense to require a highly trained health physicist to oversee a handful of low-activity radioactive sources that pose little risk to anyone. On the other hand, there are any number of firms that have fairly sizeable radioactive sources – possibly used for geotechnical investigations or for industrial radiography – that can cause problems if they aren’t used properly. And that doesn’t even get into companies that might use x-rays or even particle accelerators in their work. I know I’m biased – but I would rather see a potentially lethal source overseen by a professional health physicist who has other duties to fill his or her spare time, as opposed to putting such sources into the care of a person for whom radiation safety is an unwelcome afterthought.

To their credit, the Nuclear Regulatory Commission and the Department of Energy are working to address this shortage by offering grants to universities to help build new educational programs as well as offering fellowships to encourage students to study this field. At the very least it makes sense to continue these programs and perhaps even to ramp them up so that the number of fellowships is enough to offset the continuing retirements of AEC-era health physicists. But a fellowship is not effective if nobody knows what it’s for – there simply must be a reciprocal effort to help make students aware of the profession and to let them know that there is much more than nuclear energy (or nuclear weapons production) to the profession. To their credit, the Health Physics Society has a long history of working with the nation’s science teachers to help them better understand radiation science – it might be appropriate to also start working with high school guidance counselors and with university student organizations (such as the Society of Physics Students and their counterpart in other scientific and technical degree programs) to help spread the word that radiation safety is a great potential career option. Working with science teachers is a great start, but students make their career decisions in college as well as in high school – HPS needs to find ways to actively engage students at both levels of education if they are to have a chance of attracting new students into their profession. At the very least – particularly important in today’s economy – it might interest students to know that the shortage of HPs is such that anyone graduating without a felony conviction is likely to have multiple job offers, most of them fairly high-paying.

I’d like to close on a more personal note to say that I never planned to be a health physicist and was in my mid-30s before I realized that this was going to be my profession. Even after 8 years of practicing radiation safety in the Navy my plan was to work in the field to help pay for college – better than flipping burgers or stocking groceries. I was surprised to find that the profession was far more varied and far more rewarding than I had imagined and my work has taken me to more than 30 states and 25 foreign countries as well as giving me the chance to work on a number of fascinating projects with respected colleagues I think the world of. I can whole-heartedly recommend a career in health physics to anybody – and given what I have mentioned earlier in this posting, I really hope to see a surge of junior colleagues in the years to come.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety

The post A profession nobody’s heard of appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

First, some interesting further information:

• A number of surveys have now been performed on the contaminated tissue boxes from California to New York. The highest radiation dose rate to date has been almost 20 mR/hr on the surface of a box and about 0.1 mR/hr at a distance of a meter. This corresponds to about 50 or so µCi (microcuries) of radioactivity in the most-contaminated boxes – a level that is not hazardous, but that does call for regulatory controls.
• Interestingly (to my inner geek, anyhow) is that there have been reports that individual sides of the tissue boxes have different radiation dose readings – sometimes varying by as much as 30% or so. The reason this is interesting is that each tissue box is fairly small – about a half pound of steel from a batch of steel that probably weighed several tons. In all honesty, I had expected the radioactivity to have been evenly blended into the steel and I’d have expected the radioactivity to have been homogeneously distributed through the entire batch. The fact that we can have 30% variations in a single half-pound bit of steel suggests that the radioactivity is actually mixed more like the chocolate in fudge swirl ice cream. This, in turn, suggests that we might have – from the same batch of steel – some pieces that are “hot” and others that might completely non-radioactive. It also makes it hard to figure out exactly how much radioactivity was melted down in the first place.

And now, a few issues that are worth considering:

• Steel is normally made in batches of several tens of tons to a few hundred tons each. Thus far we know of, at most, only a few hundred pounds of steel that are accounted for in the tissue holders. So we have to ask ourselves where the rest of the contaminated steel has ended up. Is it yet to be made into consumer products? Or was it made into consumer products that have yet to be distributed? Did it end up in consumer products that were shipped elsewhere? Are these products destined for shipment here, to Europe, for internal Indian markets, or somewhere else? According to a Nuclear Regulatory Commission notice to state regulators the Indian government has been tracking the batch of steel and trying to figure out exactly where the Co-source came from, and where the rest of the steel ended up, but as of January 30 there are still more questions than answers.
• Another question worth asking is where the Co-60 came from. One possibility is that it came from the source(s) that caused the problem in 2010. But if that’s the case then we have to wonder where the contaminated steel has been stored for nearly two years and why it wasn’t found earlier. It’s also possible that the Co-60 that contaminated this batch of steel is a different source from the one that was lost – that would at least answer the question as to where the cobalt has been the last few years, but it raises even more troubling issues. I’d hate to think, for example, that India has lost two large radioactive sources in two years – that would suggest that there might be a breakdown in India’s control over radioactive sources.
• Yet another concern is whether or not this has happened elsewhere and simply hasn’t been caught. Many nations – the United States is among them – have fairly extensive networks of radiation sensors and are more likely to catch stray radioactive materials at the ports of entry or on the road (although hopefully before they cross the continent!). Other nations are not so diligent and don’t have the same resources to throw into looking for radioactive materials – we have to wonder if the United States is the only nation to which the contaminated steel has been shipped, or if it is just the only nation that has found it so far. As of now there simply is no information as to whether or not contaminated steel – from India, China, or some other nation – might be floating around, say, Africa, Latin America, or elsewhere. Hopefully the Indian regulatory authorities will be able to track this down shortly. And let’s not forget  the steel mill that melted the Co-60 source might have residual contamination.  When a Spanish steel mill was contaminated in 1998 it cost millions of dollars to clean it up again. This is why there are radiation detectors throughout the American scrap metal system (purchased by the businesses – not by the government, I should point out).

At this point I should be clear that these tissue boxes do not pose a health risk to anyone (although people who have purchased them are encouraged to return them to Bed Bath & Beyond just to be safe). But this incident does point out some weak points in the global controls over radioactive materials.

The fact that a radioactive source can make its way – undetected – into scrap metal and thence into a batch of steel, that the loss of the source was apparently not noticed for an indeterminate period of time, that the contaminated steel was shipped to a number of processing facilities and then to the United States, and that we still have not accounted for more than a fraction of the steel (or the radioactivity); all of this should be cause for concern. It is easy to take India to task on this case, but the fact is that this could happen in many nations – what is needed are for more nations (preferably all nations) to follow international standards on radioactive source accountability. Not only that, but more nations that use radioactive sources need to require their scrap yards and steel mills to screen for radioactivity – the relatively modest cost of the screening equipment pales in comparison to the cost of a single contaminated batch of steel.

The International Atomic Energy Agency (IAEA) is apparently working to finalize a code of conduct that should help to address some of these issues. This will likely supplement or extend the “Spanish Protocol” developed in the aftermath of a 1998 accident in which a Cs-137 source was melted into a batch of steel in a mill in Spain. And, lastly, I’d like to recommend a wonderful report by the National Council on Radiation Protection and Measurements (NCRP Report 141, Managing Potentially Radioactive Scrap Metal). This report is the most comprehensive report  of which I am aware on this topic and is well worth reading if you want to learn more.

Finally, I’d like to thank my colleagues David Allard, Jim Yusko, and Joel Lubenau for their thoughtful comments and information on this and related topics. Jim and Joel in particular have done yeoman’s work to keep up on the problem of orphaned sources and the problems they can cause.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety

The post Radioactive tissue boxes redux appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

In 1974 the Nobel laureate Richard Feynman gave the commencement address to the graduates at the California Institute of Technology – for his topic he coined the term “cargo cult science” and spoke about the possibility that a scientist can come to apparently scientific conclusions that are not scientifically useful.  Feynman didn’t think that the scientists were incompetent or deceitful – rather, he felt that most cases of cargo cult science stemmed from scientists fooling themselves by not seeing the flaws in their experiments. The cargo cults that the title referred to arose in the South Pacific in the aftermath of the Second World War – natives would build runways, wooden “control towers,” and even wear simulated headsets in an attempt to lure back the planes and people who had so impressed them. To Feynman, cargo cult science occurs when we follow a complex set of procedures that produce a result that, unfortunately, lacks scientific validity.

Feynman was not the first Nobel laureate to tackle this topic – he was preceded by Irving Langmuir who coined the term “pathological science” in a 1953 lecture at the Knolls Research Laboratory. In his lecture Langmuir noted that pathological science displays a number of symptoms:

1. “The maximum effect that is observed is produced by a causative agent of barely detectable intensity, and the magnitude of the effect is substantially independent of the intensity of the cause.
2. The effect is of a magnitude that remains close to the limit of detectability; or, many measurements are necessary because of the very low statistical significance of the results.
3. Claims of great accuracy.
4. Fantastic theories contrary to experience.
5. Criticisms are met by ad hoc excuses thought up on the spur of the moment.
6. Ratio of supporters to critics rises up to somewhere near 50% and then falls gradually to oblivion.”

Langmuir also cited a number of examples of pathological science, most of which have passed into oblivion in spite of having been well-known at the time. But we can think of some modern-day equivalents – the cold fusion controversy of 1989 comes to mind fairly quickly as does the speculation that vaccines can cause autism (which was thoroughly debunked recently when the scientific papers supporting this supposition turned out to have been fraudulent).

There is one obvious difficulty here – many of today’s accepted scientific theories would have been considered pathological science at some time in the past. Consider quantum mechanics – what would Newton have made of a theory that claimed the universe operated largely by chance? To Newton quantum mechanics would certainly have been considered a “fantastic theory contrary to experience,” it makes claims of great accuracy, and the effects would have been close to the limits of detectability – in fact, Newton would have considered quantum mechanics to meet at least 4 of Langmuir’s criteria for pathological science. It is quite possible that, in Newton’s day, some of our most successful scientific theories – quantum mechanics, quantum chromodynamics, and relativity theory, to name a few – may well have been considered pathological if only because they run so contrary to the world that we can observe and because there were no instruments capable of making the measurements needed to confirm (or reject) the theories’ predictions.

So how can we really know whether today’s “junk science” will remain “junk” or if will someday be vindicated? The fact is that we don’t – but there are a few of Langmuir’s criteria that might still be relevant. For example, for all its inscrutability, quantum mechanics has steadily gained adherents as more experiments are performed – contrary to Langmuir’s final criterion. In addition, when objections were raised in the early says of the theory, the responses were far from ad hoc – they were fairly well-considered and they helped to advance the theory. In these areas, at least, the theory of quantum mechanics may well have stood up as a legitimate scientific theory.

It is also worth noting that a huge number of scientific theories have made predictions that could not be verified for years or decades, yet they were still felt to be sound science (as opposed to junk or pathological science). Physicists Bose and Einstein, for example, predicted the existence of the Bose-Einstein condensate 70 years before it was first created in the laboratory, yet it was accepted that at some point the technology would exist to create it. It could be that some aspects of pathological science (by whatever name we call it) fall under Supreme Court justice Potter Stewart’s famous comment about pornography – that even if it can’t be precisely defined, we know it when we see it.

Politics and commerce seem to be where the majority of junk science claims are made – on many issues it seems that each side tries to bolster its arguments with scientific “theory” while attacking the others’ science as being junk. The climate change controversy falls into this category – at least now that it has entered the realm of politics – with each side of the issue accusing the other of using junk science.

This particular posting will not go much further on this topic but it does set the stage for future postings. From time to time I plan to use these criteria to examine various topics that are claimed to be junk science or that appear to be – we’ll see how they stack up against Langmuir’s and Feynman’s criteria to try to decide if the science (or the claim) holds water.

The post Pathological junk cargo cult voodoo and just plain bad science appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Normal bone marrow

There’s nothing like a good fright to spark people into action. Tell someone that they need to have a triple bypass and they’re likely to finally get around to exercise and healthy eating; diagnose a person with lung cancer and they might finally stop smoking. A good enough scare can get people to stop drinking, get them into church, can get them to install home alarm systems, and so much more – whatever is needed to help protect against whatever caused the scare. The last several years the threat of nuclear and radiological terrorism has given us all a good scare and one of our responses has been to throw a lot of money into improving our ability to respond medically to such an attack. A lot of strategies have been pursued – I’d like to talk about two of them (one for diagnosis and the other for treatment) that struck me as being particularly noteworthy.

Diagnosis

When it comes to radiation health effects everything comes down to dose – a person with 100 rem (1 Sv) will likely develop radiation sickness, 400 rem (4 Sv) has a 50% chance of being fatal without medical treatment, and 900 rem (9 Sv) will almost certainly be fatal with even the best medical attention. Knowing a person’s radiation dose not only helps physicians to choose the proper course of treatment but it also helps them to understand how much weight to give radiation effects when assessing a patient’s overall condition – a patient who has received only 25 rem (0.25 Sv) for example isn’t likely to experience significant health effects and the physicians can concentrate on non-radiological concerns (broken bones, lacerations, and so forth). One way to do this is to carefully examine the cell’s chromosomes for specific types of damage that are correlated with radiation exposure The problem is that determining a person’s radiation exposure – called biodosimetry – is time-consuming and complex and, in the event of a large-scale population exposure, getting accurate biodosimetry for a large number of people can take weeks. This is far too long to be useful.

In the last few years a Columbia University team led by David Brenner has developed an automated system that addresses many of these problems – the Rapid Automated Biodosimetry Tool(abbreviated RABiT).

The RABiT system is able to perform biodosimetry on as many as 30,000 samples daily – a huge advance over current techniques. Without going into the details let it suffice to say that the RABiT system adds an amazing level of capability to our national radiation biodosimetry capacity – Brenner and his colleague Guy Garty (others have contributed as well, but Brenner and Garty are the major forces behind this work) are to be commended for a genuinely innovative approach to solving a huge problem.

The biggest problem with using the RABiT system is the sheer logistics – in order to be effective there has to be a way to collect and process tens of thousands of samples daily, and this in a city that will be trying to grapple with the aftermath of a radiological or nuclear emergency. Not only that, but there is little room for error in sample identification – every single sample must be able to be unambiguously linked to the person from whom it was collected to make sure that everyone receives the appropriate medical care. And even more fundamentally, there have to be facilities to collect these samples and the population has to know where these facilities are (and to be able to reach them). These problems are not insoluble, but they are very real and, until they are solved, the RABiT system cannot be effectively implemented.

Yet another factor is that any large city that has been attacked will need to have more than one RABiT device available – even a network of 10 of these devices running around the clock will take 2-3 days to run a million samples. But it doesn’t make sense to have a number of expensive machines sitting around gathering dust while waiting for a radiological or nuclear emergency – this would be a waste of money and a waste of resources, in addition to the fact that we would have no way to know whether or not the machines (and the staff needed to operate them) would work when they’re needed. For this reason it makes sense to develop other routine uses that would justify maintaining a number of these devices in continual operation – then, in the event the worst happens, they could be converted from routine to emergency operation, rather than starting them up from scratch. For this reason Brenner and Garty are teaming up with a number of other universities and governmental agencies to look for routine uses that would support this unique capability (if you’re interested, the grant proposal deadline is still two months away).

Treatment

Knowing how much radiation dose someone received is one thing; doing something about it is another. There was another fascinating development that was published by Dana-Farber physician Eva Guinan and a number of colleagues just a few months ago (November 23, 2011) in the journal Science and it deals with treating people for high levels of radiation exposure. For the first time there seems to be promise of a treatment that could help to keep people alive who might otherwise die of high radiation exposure – if this pans out it could be hugely important.

Some of our tissues and organs are more sensitive to the effects of radiation than others. Oxygen tends to enhance the amount of damage a given amount of radiation will cause so cells that are well-oxygenated tend to be more radiation-sensitive than are the less-oxygenated cells. Cells that reproduce rapidly are also more radiation-sensitive, as are less specialized cells. Putting all of this together helps to explain why, for instance, our neurons are relatively radiation-resistant (they are highly specialized cells that divide only rarely) and why the cells that line our digestive tract and our blood-forming organs are among the first affected by radiation. In fact, a drop in blood cell counts is one of the earliest signs of excessive radiation exposure and this drop can become life-endangering at higher radiation doses.

Relatively low doses of radiation (up to about 100 rem or 1 Sv) will cause blood cell counts to drop but it doesn’t become life-endangering until the dose gets to about 400 rem (4 Sv) – at this level of exposure (without medical care) about half of those exposed will die. With medical treatment, much of which is aimed at supporting a patient whose immune system and blood-forming organs have been severely compromised, the 50% lethal dose increases to about 800 rem (8 Sv). A major cause of death is infection due to the destruction of an organism’s immune system.

Mice (the organism Guinan’s group tested, since it’s not quite ethical to expose humans to near-lethal radiation doses in experiments, no matter how well-intended) a radiation dose of 700 rem (7 Sv) is nearly always fatal, killing between 95-100% of the mice exposed. By treating mice with two drugs – one that helps replace some proteins that are crucial in helping fight off infection and a powerful antibiotic. Not only that, but the bone marrow of exposed mice recovered much more quickly after treatment. With these drugs, between 70-80% of the exposed mice survived, a phenomenal turnabout.

Both of the drugs Guinan tested are already used in people, albeit for different purposes, and both have been shown to be safe. This means that, even if the patient’s dose is not precisely known, there is little down side to treatment. Another plus is that the adverse health effects of radiation take some time to appear – this treatment is effective even if it takes place a day after the exposure. The bottom line is that, if tested and approved for human use, this treatment promises to be able to save lives. But, of course, it does need to be tested to ensure that it lives up to its promise.

Summary

We may never have a large-scale radiological or nuclear emergency that would call for these developments. Consider – until Chernobyl there was no need for large-scale biodosimetry and after Chernobyl there was no further need for over two decades with the Fukushima accident. And even Chernobyl had only a relative handful of people who would have benefitted from Guinan’s work. But both of these developments offer the potential for utility in more routine circumstances – that being the case it seems to make sense to invest today to develop this new technology and drug therapy so that we will have them available should we ever need them in an emergency, and so that we can use them more routinely even in the absence of another major disaster.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Some new developments in radiation diagnosis and treatment appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

One can guess that these killings are aimed, like the Stuxnet computer virus, at slowing down Iran’s progress towards developing nuclear weapons. Targeting critical (if you’ll pardon the pun) individuals is understandable, but one has to wonder how effective a tactic this might be. One way to think about this question is to consider what is required to develop a nuclear weapon and to ask if the tactic of targeted assassination is an effective way to interrupt this process. The minimum requirements would seem to require an aspiring nuclear power to have:

1. The basic theoretical knowledge
2. A process to produce fissionable materials
3. The technological ability to produce fissionable materials and assemble a nuclear weapon

Consider the first point – the basic theory behind nuclear weapons is so well-known that, in 1977 a Princeton undergraduate student wrote a term paper in which he outlined the design for a nuclear weapon. And, for that matter, most of the underlying science is readily available on-line, not to mention in books and other references that are readily available. As one example, I did an on-line search using the terms “nuclear weapons design” (which probably endeared me to whoever keeps track of internet searches) and found a surprising amount of information in less than an hour.  At one point in the past – perhaps during the early days of the Manhattan Project, assassinating a few key scientists would have put a crimp in American efforts at nuclear weapons development but we are far beyond those days. Killing Iranian nuclear scientists might delay an Iranian nuclear weapon but it may not be anything more than a speed bump.

Producing fissionable materials is more of a bottleneck. Natural uranium, of which only about 0.72% of the atoms are fissionable U-235, cannot sustain nuclear fission without a lot of coaxing (using heavy water or graphite to help a reactor attain criticality) because there simply aren’t enough U-235 atoms to keep a chain reaction going. In order to maintain a chain reaction for a critical nuclear reactor the amount of U-235 must be boosted to at least 1%, and most commercial nuclear reactors use fuel in which the U-235 concentration has been enriched to at least 3%. Weapons-grade uranium contains as much as 90% U-235 (anything in excess of 20% is outlawed for non-nuclear weapons states). Uranium enrichment is simple enough in theory but, in practice, it is neither easy nor cheap – the current “best practice” is to use a series of high-speed centrifuges to separate the very slightly lighter U-235 atoms from the very slightly heavier U-238. These centrifuges are tricky to build and are even trickier to chain them together in what is called a “cascade,” but the process is merely difficult and the basic technology is decades old. And we have to remember – under the nuclear non-proliferation treaty any nation can legally enrich uranium to 20% – it is only illegal to exceed that level. So Iran is perfectly within its rights to enrich uranium as high as 20% – just as the Dutch and Japanese are permitted to enrich uranium. But we don’t worry much about the Dutch or Japanese developing nuclear weapons – we trust them to uphold their treaty obligations.

The third factor is access to the level of technology needed to produce nuclear weapons. The problem here is that the technology needed to produce weapons-grade uranium is exactly the same as the technology needed to produce reactor-grade uranium – any nation that can do the one can accomplish the other. The other way to produce fissionable materials is by producing plutonium in a nuclear reactor – this technology is also decades old. Virtually any nation on Earth has access to the level of technology needed to produce fissionable materials should they choose to spend the money (and to risk the international opprobrium) to do so. And once the fissionable materials are in hand, assembling them into a nuclear weapon is not simple, but is certainly not overly difficult – again, this is something that the Manhattan Project accomplished nearly 70 years ago.

The bottom line is that developing nuclear weapons no longer requires a Manhattan Project (according to Peter Zimmerman, a former scientific advisor to the Senate’s Foreign Relations Committee). One of America’s most talented nuclear weapons designers, Ted Taylor, shared this viewpoint in a series of interviews with journalist John McPhee that were the basis for a fascinating book, The Curve of Binding Energy.  In the Manhattan Project days neither the theory nor the technology were readily available – had our enemies launched an assassination program they could well have derailed the Manhattan Project, or could at least have delayed our first nuclear weapon by a matter of years. But that is hardly the case today – it is almost certainly impossible to assassinate away the Iranian program. Killing crucial people and tinkering with Iranian technology can delay things, but likely no more than that.

But there is a little more to the issue than this – what University of Edinburgh professors Donald MacKenzie and Graham Spinardi call “tacit knowledge.” Tacit knowledge is the knowledge handed down from master to apprentice – think of Yoda teaching Luke Skywalker how to become a Jedi. Tacit knowledge encompasses the secrets of how to turn theory into practice and as MacKenzie and Spinardi point out, there is a LOT of tacit knowledge involved in nuclear weapons design. The question is whether this tacit knowledge is essential to making a working nuclear weapon or a good nuclear weapon. And here, even MacKenzie suggest that making a crude nuclear bomb might not require a high level of tacit knowledge, provided the designers aren’t picky about details such as developing a miniaturized or high-yield device. Bringing this back to the question of assassinating Iranian nuclear scientists we have to ask ourselves if the Iranian nuclear program is at a level of sophistication at which tacit knowledge plays a major role – if there are not yet any Iranian nuclear Jedi masters then whoever is carrying out these attacks is killing apprentices, and they might well be virtually interchangeable. Without knowing the exact state of the Iranian program we might not be able to know whose loss might (or might not) have a significant impact.

So – with all this in mind – we have to ask ourselves if these assassinations are ethical and if they are effective.

We never questioned our development of nuclear weapons – we were the good guys after all in both World War II and the ensuing Cold War while the Nazis and the Soviets were the bad guys. We didn’t worry about the British and French nuclear weapons either – they were also the good guys. And when the Soviets and the Chinese developed these weapons we weren’t delighted but, as musician and humorist Tom Lehrer pointed out, “the balance of power’s maintained that way.” It wasn’t ideal, but it was something that we could live with because we felt we could at least trust these nations to act rationally. Not only that, but we had no way to throw a monkey wrench into those nations’ progress – at least not without starting a war that we were loath to undertake. The reason that Iran poses a more difficult problem is that we don’t trust them and we don’t know if we can count on the Iranian leaders to act as rationally as the Soviets and the Chinese.

As far as the ethics of assassination go there are a few considerations. One is whether or not such a program is likely to achieve its desired ends. If the desired end is to put a halt to Iranian nuclear weapons work, then assassinations will almost certainly not work. But if the intent is simply to delay such a program, then they might have some utility, but without knowing how much depth the Iranians have on their bench we cannot know how much of a delay – if any – there might be.

Whoever is ordering these assassinations also has to weigh what is at stake compared to the killing that is taking place. The answer here seems simple – a nuclear attack might kill hundreds of thousands of people so killing a handful to prevent such a high toll seems a reasonable trade. This argument – utilitarianism – is simply a matter of mathematics; what provides the greatest good for the greatest number. But is it legitimate to wonder if ethics can be boiled down to simple math. What if, for example we were told that a terrorist group was going to detonate a nuclear weapon that could kill a half-million people, but they would forgo their attack if we agreed to execute a hundred thousand citizens. Clearly the mathematics would argue in favor of the executions – but we have to ask ourselves if this is an ethical course to follow. Even with a life-saving ratio of 5:1 I suspect most of us would say that purposely executing 100,000 people is unethical – even if doing so would save a half million lives. So numbers alone do not make a decision ethical. But do the ethical books ever balance taking this approach? Is it OK to execute 1000 citizens to stave off a nuclear attack? What about 100? Or 10? What if those to be executed are the citizens of a neutral nation – would this make the executions more or less acceptable? What if they were prisoners? Or in the case we’re talking about – what if they are nuclear scientists helping to develop a weapon you are worried about? It’s a tough question – one for which there is likely no answer to which we would all agree. But the fact remains that Iran is not presently at war with any other nation – it might be ethical to assassinate key weapons scientists in an enemy nation, but does Iran’s relationship with any other nation fall to this level? Again, there is likely no universal answer to this question.

The other question of course is – ethics aside – the goal of such a program and whether or not a program of targeted assassination is likely to be effective. In this case if the goal is simply to delay Iran’s development of nuclear weapons, I would suggest that the delay is likely to be inconsequential. As noted earlier, the information and technology are all “out there” and they are simply too widely disseminated to stuff this particular genie back into the bottle. And if the goal is to halt Iranian nuclear weapons research, then the goal is even less likely to come to pass. Destroying machinary– the goal of the Stuxnet computer virus – or delaying technology development through economic sanctions and restricting trade in crucial items can really put a crimp in the process of developing nuclear technology, but it is unlikely that any crucial knowledge will be held by only a single person. At the same time, targeted assassinations might actually be counterproductive – at some point Iran is likely to realize that it has to produce more nuclear scientists, to protect them better, and to urge them to progress faster. Similarly, if the goal is to dissuade other nuclear scientists from making progress, this goal is almost certain to fail- in fact, the remaining scientists may well feel that their safety is best protected by the rapid development of a working nuclear weapon.

The bottom line is that the ethics of these assassinations is murky at best – balancing the possibility that Iran might develop nuclear weapons (and the use to which these weapons might be put) against the lives of the scientists and engineers who are involved in supporting this development process. And even putting aside ethics for a moment and asking only whether or not such a program is likely to achieve its ends we can only say “I don’t know” because the technology and basic science are already so well-known and so well-established. The fundamental question is whether the certainty of several small deaths in Iran balance the possibility of large-scale death elsewhere – this is a question that must be asked, even if there is no simple answer.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post A small death in Tehran appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

At the moment much of the world seems to be suffering from the Garcia effect in the aftermath of the Fukushima accident. Germany and Switzerland have both decided to put a halt to their nuclear power programs, America’s nuclear renaissance seems to have slowed somewhat, and Japan is trying to figure out how to substitute alternative energy sources for nuclear power – not to mention other nations (Austria, Spain, Taiwan, Mexico, and Belgium) that have announced they will either phase out nuclear power altogether or to halt construction of new reactors. It is understandable that the world might feel an aversion to nuclear power at the moment, just as I felt an aversion to sake after my one unfortunate experience. The problem is that nuclear power plants take decades to plan and build. My sake aversion was overcome during the course of a meal with my Japanese hosts but it can take a few decades to design, license, and build a new nuclear power plant. Given the stakes – and the length of time it takes to construct a nuclear reactor – it might make sense to ask if our current nuclear power aversion is well-founded.

The fact is that nuclear power is complex, but it is no more dangerous than is any other form of energy. In fact, looking at the number of deaths per megawatt of energy produced, solar power is far and away the most dangerous form of energy – but this statistic is somewhat skewed because of the large number of people who fall off of the roof installing solar collectors and because solar energy is so small a part of our energy mix. But the fact remains that on a routine basis (i.e. under normal operation) nuclear energy – including mining, transportation, and operation – is less deadly than many other forms of energy generation. Data summarized by the International Atomic Energy Agency makes it clear that nuclear energy is less deadly (in terms of annual fatalities per gigawatt year of energy produced) than are coal, oil, gas, hydroelectric, or solar energy. This should be obvious to anyone who follows the news of coal mining disasters in the United States and China, and it doesn’t even start to address deaths due to air pollution from fossil fuel-burning power plants. Of course the IAEA can be accused of cooking their statistics to make nuclear energy look safer than it really is, not to mention the fact that accidents like Fukushima and Chernobyl raise questions about the impact of reactor accidents. But the fact is that nuclear energy is neither the least nor the most dangerous form of energy available.

Similarly, nuclear energy is not the only form of energy to release radioactivity into the environment. Coal, due to the geochemistry of uranium, contains radioactivity that is released when it is burned. Not only that, but the geologic conditions under which petroleum and natural gas formed mean that these deposits also contain radioactivity – bringing these fossil fuels to the surface releases radioactivity into the environment. Incidentally, geothermal energy production also produces radioactive liquids and generates radioactive byproducts (the Department of Energy has published a number of documents describing the amount of natural radioactivity found in various fossil fuels, many of which are available as PDF downloads). Without going into all of the details it is safe to say that nuclear energy releases more radioactivity into the environment than do some forms of energy production (e.g. solar or tidal) but causes less radiation dose to the public per gigawatt hour of energy produced than do coal, natural gas, or petroleum-burning.

Of course this doesn’t get into the accidents, but even here nuclear energy is not uniquely dangerous. The World Health Organization estimates that up to 9000 people might die of radiation-induced cancer as a result of the Chernobyl accident over a period of 50 years, but the same report acknowledges that, as of its 2006 publication date, fewer than 100 deaths can be attributed to the accident. Fukushima released only about 10-20% of the total amount of radioactivity released by Chernobyl – it is reasonable to assume that the total radiation dose to the population from the Fukushima accident was no more than 10-20% of the dose to the Ukrainian and Belorussian populations. This is not to suggest that any deaths that come about as a result of these accidents are acceptable – only to note that nuclear energy is no more dangerous than any other form of energy production.

When we put all of this together it would seem that nuclear energy is neither without risk nor extraordinarily dangerous. That being the case, it could be that the knee-jerk nuclear aversion experienced by so many nations might be premature and ill-advised.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Whither nuclear power? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The tissue boxes are radioactive – no doubt about it. The question is whether or not they are sufficiently radioactive to cause health problems. At present I have been having problems finding the results of direct radiation dose measurements and without some numbers all that we have to go by are the assurances that have been printed in press releases. The Nuclear Regulatory Commission and the New York State Department of Health have noted that a person who purchased one of these tissue holders and who had a fairly typical exposure to the holder would receive low doses of radiation – New York State officials were quoted as saying that exposure to one of the boxes for an hour would be the equivalent of a chest x-ray.

I don’t doubt that this statement is factually correct but, as a scientist, I find it a little unsatisfying – I want numbers! In particular, I’d like to know what dose rate was measured from the boxes and at what distance – with that I can figure out the amount of Co-60 in each of the boxes and I can calculate the radiation dose at any distance and for any length of time. One number that I’ve heard – although without attribution – was that the tissue holders were reading less than 10 mrad/hr at a distance of 2-3 feet. This is consistent with the statements made by NRC and NYS officials, but it’s really just a guess.

When we have a situation like this there are any number of ways to go about determining the radiation dose and the risk, but there are two or three that are fairly common approaches. One is to assume the very worst combination of circumstances and to calculate the maximum radiation dose that anyone could possibly receive. If the dose calculated this was is acceptable then we can assume that the reality would certainly be OK. In this case, the very worst set of circumstances would be to assume that somebody holds one of these tissue holders in their lap continuously. So – if we have a tissue holder that’s reading 10 mrad/hr 3 feet away it will read about 100 mrad/hr at a foot and about 1 rad/hr at a distance of 4 inches. The radiation dose to the whole body would be a bit lower than this since most of us are more than 8 inches tall – there might be a fairly high radiation dose to the lap but radiation dose to the whole body would be lower. Even this scenario, however, would expose a person to many rads of radiation each year, and even a single rad annually is ten times the radiation exposure limit for members of the public.

But we have to ask ourselves if this dose – and the assumptions that went into calculating it – are reasonable. How long can we expect that somebody will actually hold a tissue holder and what distance will they keep it from them? I can go by my own apartment, I suppose – I have two boxes of tissues in my apartment, one next to my desk and the other next to my bed. I spend a lot of time in each of thes locations – about 6 hours nightly asleep (and about 2 feet from that tissue box at the head of the bed) and about 4 hours every evening (plus weekends) at the desk at home, with the box of tissues at my feet. If we stick with a dose rate of 10 mrad/hr at a distance of 3 feet as the standard then we can calculate that I’d receive about 100 mrad every day from tissue boxes (if I had two of this particular box in my apartment).

But what I don’t know – what I have no way of knowing – is whether or not my own tissue box placement is the same as everyone else’s, if I get the same amount of sleep as others, if I spend the same amount of time at my desk as others, and so forth. For example, if I had only one box in my bathroom my dose would be a lot lower, and if I lived in a house and not in a small (650 square feet) apartment then my dose would likely be lower yet. This is the problem with any sort of radiation dose calculation – and the risk from exposure to radioactive objects – since we don’t know how every single person will use the objects we often have to choose between a clearly ludicrous scenario that will produce the highest calculated dose or we have to develop a scenario that seems more reasonable, but that might overestimate the dose to some while underestimating the dose to others. Any set of assumptions – from the most pessimistic to the most optimistic – can be questioned. It makes the whole radiological assessment business challenging.

In the case of the Indian tissue box holders – and in the absence of any more solid information – it seems reasonable to take the statements by regulators at face value (I have a lot of professional respect for both New York State and Federal radiation regulators, who are typically quite talented – and no, I don’t work for either of these organizations and I’m not regulated by them!). This would come out to several hundred mrem of radiation exposure annually – less than what is known to cause harm, but still more exposure than we really want the public to receive. Thus, the regulatory comments make sense – while nobody is at immediate risk from these holders it is reasonable to take them off the market, keeping radiation exposure to the public As Low As Reasonably Achievable.

The issue of protecting the public from radiation exposure is important, but it’s not the only issue in this case – there is also the question of how Co-60 found its way into a bunch of tissue box holders in the first place. Co-60 is used in industry and (less frequently) in medicine – sources can range from virtually risk-free to dangerously radioactive. Interestingly, in 2010 an “orphaned” Co-60 source from Delhi University was responsible for 11 hospitalizations and a death when a radioactive source accidentally ended up at a scrap metal yard. Whether Co-60 from this source is what ended up in the metal of the tissue holders is not yet known – but at the least the 2010 incident demonstrates that India suffered one breakdown in their control of radioactive materials in the recent past and there might have been more.

Globally, “orphaned” radioactive sources have caused problems in the past and they are likely to continue doing so for years to come. The International Atomic Energy Agency has devoted considerable resources to trying to identify and control dangerous radioactive sources for years, yet there are still accidents (for copies of the IAEA reports on these accidents you can browse through the documents in the IAEA Non-Serial Publications, which are available for download as PDF files). Part of the key to keeping these sources under control is for governments to maintain up-to-date information of the whereabouts of the most dangerous sources and the other part of the problem is for governments to make sure that these sources are kept safe and secure against loss or theft. In the United States this is accomplished through something called Increased Controls that aims to increase accountability for the sources as well as for those working with them. Extending such controls to other nations is something the IAEA has been working on for years, but there is still much work to be done – as evidenced by the 2010 accident in India.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety

The post Radioactive tissues? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Of course, my kids’ appearance is not the point – the point here is that the reproductive effects of radiation are exaggerated to the point of irrationality – more so than virtually any other reproductive hazards. True – radiation can cause birth defects and it has been shown to induce mutations in animals. But the amount of radiation required to cause birth defects in humans is substantial (at least 5 rem or 50 mSv to the fetus) and the medical literature has not noted a single instance in which pre-conception radiation exposure to humans has caused birth defects when the woman eventually conceives. And if more people – physicians included – really understood these points there would be far fewer worries.

Consider – the BBC documentary Nuclear Nightmares (which was about radiation phobia) stated that the Soviet government performed a few hundred thousand abortions on women exposed to radiation after the accident and others have stated that there were at least 100,000 abortions conducted in Europe due to fears about the reproductive effects of radiation exposure. It is almost certain that few – if any – of these abortions could have been justified by the radiation exposure alone. I understand that the numbers cited are not from the peer-reviewed literature and that they might be exaggerated (although I have spoken with some who claim that the actual numbers are far higher). But the 2006 report by the World Health Organization concluded that after 20 years there had been fewer than 100 deaths attributable to radiation exposure from the accident (including radiation-induced cancers) and projected that as many as 10,000 people might eventually develop cancer from the accident – even if the WHO’s worst-case estimates come to pass and even if the abortion numbers are over-stated by a factor of 10 we will still find that fear, lack of understanding, and misinformation was deadlier than the accident itself. This is tragic.

As a medical radiation safety officer I calculated nearly 100 fetal dose estimates, usually when a pregnant woman was involved in a car crash and, while unconscious, received the “trauma series” of x-rays from head to foot, possibly followed by CT or even fluoroscopy. Sometimes when the woman woke up she told the doctor she was pregnant, sometimes she didn’t know this herself for another few weeks. In either case, our policy was that I was to be informed so that I could perform fetal radiation dose calculations and write a letter explaining the results to the woman’s OB/GYN. There was not a single case in which the fetal dose estimate was high enough to warrant taking any actions at all, even though some of the women had been advised they might need to terminate their pregnancies. And I was not alone in this – the Health Physics Society runs a wonderful feature on their website (Ask the Experts) that has a section for radiation and pregnancy. Over the last decade or so they have accumulated hundreds of inquiries on this topic and almost none of them warranted any concern at all. Sadly, many physicians in the US are taught that radiation can cause problems with pregnancy, some of them might vaguely remember a dose of 5 or 10 rem (50-100 mSv) can cause problems, but don’t know the fetal radiation dose from the radiation they might prescribe, and are then told little more. Is it any wonder they sometimes give bad advice?

The Centers for Disease Control and Prevention maintains an informative web page that includes information on the impact of prenatal radiation exposure aimed at parents and at physicians. CDC includes a table that summarizes the impact of prenatal radiation exposure based on the post-conception age and the fetal radiation dose – they conclude that for any radiation exposure that occurs less than 2 weeks into the pregnancy and for any fetal radiation exposure of less than 5 rem (50 mSv) there is no need to take any actions at all. To put this number in perspective, it can take tens of x-rays or a few CT scans that image the uterus (the exact number depends on the x-ray or CT machine being used, the amount of tissue between the x-ray beam and the fetus, and a number of other factors) to reach this level of fetal exposure. And for x-ray exposures that do not image the uterus – a chest or head x-ray for example – the dose is even smaller. But believe it or not, I even took a call from a woman who had dental x-rays wondering if she should take her physician’s advice to have a therapeutic abortion.

Having said all of this I don’t want to make it sound as though I’m advocating throwing caution to the winds – according to the ALARA principle (to keep radiation exposure As Low As Reasonably Achievable) we should not simply run up the dose through unnecessary medical imaging – I agree with the goals of the Image Gently initiative to help reduce pediatric (and prenatal) radiation exposure. But I would suggest that if the mother’s health or life are at stake then physicians should avail themselves of the tools they have without letting unwarranted fears deny them access to valuable diagnostic information. And the physicians need to remember that – before giving any medical advice about the pregnancy – fetal radiation dose should be calculated by a qualified and competent health physicist or medical physicist. Radiation health effects depend on the radiation dose – absent a solid radiation dose estimate it simply is not possible to give good, informed advice to the prospective parents.

At this point I feel I should state unequivocally that I am not attacking physicians in this or in my earlier posting. Two of my great-uncles were physicians and I have worked with a huge number of physicians in my professional career. Most physicians will never have to deal with a pregnant woman exposed to radiation – this lack of experience plus the fact that medical schools do not normally teach their students about the medical or reproductive effects of radiation helps to explain physicians’ relative lack of knowledge in this area. I honestly believe that physicians try their utmost to give solid, science-based medical advice whenever possible and most of them do what they can to give their patients the best advice possible.

The sad fact is that the programs that train our physicians – not just in the US by the way, remember the numbers from Europe – are not doing a good job of teaching their students about the impact of radiation on their patients. I discussed this in an earlier blog, where you can find references on this point. This is ironic given that, according to the National Council on Radiation Protection and Measurements, our exposure to medical radiation has increased dramatically in the last few decades. Given our society’s heavy reliance on radiation in industry, medicine, research as well as our dependence on nuclear power, I would like to think that our physicians can be better prepared to give good advice to their patients about the effects of the radiation to which they are unavoidably exposed, just as I would like to think that the public can be provided with solid information so that they can participate more fully in the process of making decisions about radiation exposure.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety, including managing an academic/medical radiation safety program at a major research university and hospital.

The post Radiation and pregnancy appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

1. Divine reasons (e.g. biblical predictions, the wrath of God, the return of a holy figure, etc.)
2. “Scientific” reasons (e.g. an alignment of planets, and alignment of stars, etc.)
3. Human reasons (e.g. nuclear war, runaway global warming, etc.)

This posting will not try to determine what might (or might not) be on the mind of a deity so the first of these categories will not be discussed, but the other two categories are certainly worth thinking about.

“Scientific” reasons As one example, in 1919 the meteorologist Albert Porta predicted that a rare planetary alignment would cause the Sun to explode. Porta’s prediction obviously didn’t pan out, leaving an opening for John Gribbon to write The Jupiter Effect, predicting the end of the world from a rare planetary alignment – with all of the planets more or less lined up from the Sun outward Gribbon anticipated that the sum of the gravitational forces would cause the Earth to tip over on its side or to trigger earthquakes, or something similar.  The latest version of the “alignment” hypotheses is the 2012 prediction – that when the Solar System passes through the exact centerline of the Milky Way galaxy the gravitational  forces (or possibly other more esoteric forces) will cause the world to end.

What all of these predictions have in common is the Earth will be stressed to the breaking point by the forces caused by some rare (from a human perspective) celestial alignment. What is interesting is that the most potentially stressful planetary alignments – with every planet lined up precisely so that, looking from the Sun, they would all overlap in the sky – happen so rarely that they are unlikely to ever occur. East Tennessee State University astronomer Donald Lutermoser figures that the most precise alignments happen only about once every 10⁴⁶ years – hugely longer than the Solar System’s scanty four and a half billion year age. Chances are that such an alignment will never occur. Other alignments are far less rare, happening on the order of every few centuries to every tens of millions of years.

Consider, for example, the passage of the Solar System through the plane of the Milky Way. The Sun bobs up and down through the plane of the galaxy like a cosmic yo-yo with a periodicity of tens of millions of years. This is a huge length of time and it’s easy to think that something that happens so infrequently might well cause the end of the world. On the other hand, the Earth is ancient and it has survived hundreds of such crossings without yet being destroyed. Odds are good that we’ll survive the next such alignment. And the same goes for the other such alignments – even something that happens only once every billion years has been survived four or five times over the history of our planet and chances are that the Earth will live through the next occurrence as well. In other words, astronomical alignments are either too rare or too common to be seriously considered as a way to end the world.

To add to that the putative mechanism doesn’t hold water either – Lutermoser also points out that the gravitational and tidal forces exerted on the Earth from anything other than the Moon and the Sun are minuscule. Tidal forces can, indeed, rip a planet apart – this is likely the mechanism responsible for the rings around Saturn and the other gas giants in our Solar System – and space science journalist Charles Choi reports a recent paper published in Nature suggesting that astronomers might soon see the Milky Way’s central black hole “feeding” on a gas cloud (and maybe even a planet or two) in the next few years. But barring a close passage close to a massive object tidal forces simply cannot muster enough force to rip the Earth asunder – were this possible the Solar System today would be filled with rubble and not planets. The bottom line is that ”science” based speculation about the end of the world – even those supposedly tied to the Mayan calendar – simply don’t hold water.  Even the real events we have records of, such as the impact responsible for the demise of the dinosaurs, were (shall we say) unfortunate for a great many species but the Earth survived. The Earth will certainly end come to an end at some point, but right now the best bet is that this will be several billion years from now.

Human causes Of course we have more worries than simple planetary alignments – people have been predicting that humanity will destroy the world for some time. Even the biblical Noah’s Flood and the destruction of Sodom and Gomorrah can be seen in this light – that humanity’s wickedness brought catastrophe (albeit divine). More recently end-of-the-world predictions have centered on our scientific and technical prowess – nuclear war, global warming, biological weapons, and more.

Undoubtedly, we can do some serious harm to the Earth’s biosphere if we put our mind to it. Even with the recent dramatic reductions in nuclear arsenals, for example, there are still more than enough weapons in the world (more than 20,000 as of 2011 with a cumulative yield of as much as 5,000 Mt) to destroy our civilization and, possibly, to destroy much of the life on Earth. But the asteroid impact responsible for killing the dinosaurs released about 10,000 times this amount of energy. A bummer for the dinosaurs (and for about 75% of all the Earth’s species of life), but the Earth is still here and life – obviously – made it through the cataclysm.

Radiation is something that probably was not released after a major impact, but even here there is precedent. A number of astronomers (John Scalo and Craig Wheeler at the University of Texas in Austin, the University of Illinois’ Brian Fields, and others) have concluded that radiation from nearby supernovae and gamma ray bursts has likely been high enough to have an impact on terrestrial life several times since life first appeared. Fields, in particular, predicted that we might even find evidence of supernova-produced radioactivity on Earth, a prediction that was confirmed in the early years of this century by German astronomer K. Knie with the discovery of “live” ⁶⁰Fe in deep-sea sediments (with a half-life of “only” 2.6 million years, this nuclide would have decayed away long ago were it not replenished somehow). The bottom line is that the radiation and radioactivity from a nuclear war are higher than what is considered normal, but they are not necessarily unprecedented over the Earth’s history.

Nuclear war – even one that destroyed humanity – would be a major blow for life on Earth, but it is unlikely to sterilize the planet. Life might be set back millions or even tens of millions of years, but it would recover just as surely as it recovered after the five major mass extinctions and every other catastrophe that has afflicted our planet.

Global warming also falls into this category – for most of the Earth’s history the Earth’s poles were bereft of ice and temperatures were much higher than what we have today. Even high carbon dioxide levels are not unique to our time – Yale University professors Robert Berner and Zavareth Kothavala have estimated that atmospheric concentrations of this greenhouse gas have been as much as 25 times those we see today (about 500 million years ago) and, with the exception of the Carboniferous period (about 315-270 million years ago) our atmosphere has almost never contained less carbon dioxide than we have today. This is not to say that we can relax our efforts to stave off global warming – more to point out that the Earth has survived far worse than we can apparently dish out. Global warming would be a tragedy without parallel in human history, causing death, disease, extinction, and so forth – but it would almost certainly not be the end of humanity, let alone the end of the world.

So is the end of the world nigh? Barring divine intervention (which is beyond the scope of ScienceWonk) it doesn’t seem likely – at least not within the next several billion years. This is not to say that we can’t do damage – we can do considerable harm if we set our minds to it, or even through sheer negligence – but after over four billion years and countless natural disasters the Earth and the life it holds has made it through quite a bit. At the least, I’m making plans for 2013 and beyond.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post The End of the World (as we know it)? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

One of the radiation survey maps at the Fukushima dai-ichi facility (http://maptd.com/fukushima-daiichi-radiation-survey-maps/)

Imagine trying to describe the world without using units. As I write today I’m watching football on TV – I’d never really paid much attention before, but now that the topic is on my mind I am amazed by the welter of units being bandied about by the commentators. Describing a player as “big and tall” doesn’t convey as much information (or as much awe) as saying that they are 6’7” and 335 pounds, and a 99-yard punt return is certainly more impressive than a “really long” run of indeterminate length. Not only that, but without units of some sort we have no objective basis of comparison – my “medium” drink would be far too much for a toddler and would be a trivial amount for the bonus-sized football player mentioned earlier. This is why we use units – to help us quantify the world around us, if only to help with these comparisons. Radiation safety is no different – it’s just that the units are inscrutable to most non-practitioners. My goal here is to take a step back from some of the more involved postings to discuss what the radiation safety units mean and to give a feel for levels that are considered normal, interesting, or alarming (by “interesting” I mean levels that are obviously elevated but that are not dangerous). I’ll also define both the SI units and those that are still most commonly used in the United States (in spite of the best efforts of the Health Physics Society to switch entirely to SI units). With each of the units discussed remember that the typical multipliers (micro, milli, kilo, mega, etc.) apply, so there are 1000 millirads in 1 rad and a million microGy in one Gy.

Radiation is nothing more (or less) than the transfer of energy from one place to another. The photons bombarding me right now have brought energy from incandescent gases on the Sun (93 million miles or 150 million km distant) into my apartment, and a fastball is a form of particulate “radiation” that transfers energy from a pitcher’s arm to a catcher’s mitt (or to the batter’s bat). What we are concerned about in radiation safety is ionizing radiation, which is radiation that has enough energy to strip an electron from an atom, creating an ion pair that can go on to cause health problems.  With radiation we are primarily concerned about radiation dose and the dose rate – discussed below.

Radiation dose is a measure of the amount of energy deposited in a substance by the radiation that is striking it and it is measured in units called the Gray (SI) or rad (US). The formal definition of the Gray is the deposition of 1 Joule of energy per kilogram of absorber and depositing 100 ergs of energy per gram of absorber exposes it to 1 rad – do the unit conversions and you find that 1 Gy = 100 rads. Note that this has nothing at all to do with the amount of biological damage caused by the radiation, these units refer only to the amount of energy deposited. Some notable radiation doses (from a standpoint of health effects) are noted here:

Skin burns and cataracts can also be caused by radiation exposure at dose (to the skin or to the eye) of about 300 rads (3 Gy).

Equivalent dose takes into account the fact that some types of radiation cause more harm – and are more likely to kill cells or to cause cancer – than others and is measured in units of rem (US) or Sievert (SI). Alpha particles, for example, are big and are much more likely to cause irreparable DNA damage than are the lighter beta and gamma radiations. So a person exposed to 1 rad (0.01 Gy) of alpha radiation will accumulate about 20 times as much DNA damage – will be 20 times as likely to develop cancer later in life – as a person exposed to the same level of beta or gamma radiation. To calculate equivalent dose we just multiply the absorbed dose (rad or Gy) by the relative biological effectiveness of the radiation in question. Thus, a person exposed to 1 rad of alpha radiation will accumulate 20 rem of equivalent dose. Radiation regulations are based on both short-term and long-term risk so regulatory dose limits are typically given in terms of dose equivalent (rem or Sv) rather than absorbed dose (rad or Gy).

Dose rate is just as it sounds – the rate at which energy is being deposited in an absorber. In a sense we can consider the dose rate as the speedometer and the total dose as the odometer – a high dose rate gets you to a dose limit (or a given health effect) more quickly than a lower dose rate. A person exposed to a dose rate of, say, 5 mr/hr (50 microGy/hr) will take 1000 hours to reach their regulatory dose limit. This table might help to give a feel for the significance of various dose rates. For the sake of compactness I’m listing only the US units – for SI units simply divide by 100.

Radioactivity is a fundamental physical property of atoms that have excess energy and that give up this energy by emitting radiation. Objects may (or may not) be heavy, dark-colored, flammable, radioactive, liquid, hot, and so forth. However, unlike some of the properties noted above, an atom’s status of being radioactive can only be changed by its decay to a non-radioactive (stable) condition by emitting radiation. Radioactivity cannot be destroyed by fire, extreme pressure, or any other known physical process. Radioactivity is quantified by measuring the rate at which atoms decay (emitting radiation) in an object – it’s measured in units of becquerels (SI) and curies (US). It is important to understand that the amount of radioactivity present does not necessarily have anything to do with the total amount of material you might be looking at – one gram of radium-226 for example has the same amount of radioactivity as about 3 tons of depleted uranium. So when we refer to a radioactive source as being “high-activity” we are referring only to the rate at which atoms are decaying in the source.

The SI unit for radioactivity is the becquerel (abbreviated Bq) and a 1 Bq source will undergo 1 decay per second. The US unit of radioactivity is the curie (Ci) and a 1 Ci source will experience 37 billion decays per second. Thus, 1 Ci = 37 billion Bq (37 GBq). All things being equal, a high-activity source poses a greater potential risk, but the amount of risk posed by a source of any given activity level depends very strongly on the radionuclide that makes up the source – the amount of alpha-emitting polonium used to kill Alexander Litvenenko in London in 2006 was far lower than the amount of cesium needed to cause harm.

Radioactivity is found naturally in soil, water, air, and food around the world. In fact, I have measured radioactivity from natural potassium in a bunch of bananas and in salt substitute, and I collect naturally radioactive rocks and minerals. The amount of radioactivity found in natural objects such as these is normally measured in picoCuries (pCi) where a million pCi go into a single µCi and a million µCi comprise a curie. One Bq is equal to 27 pCi. Natural objects (soil, bananas, etc.) generally contain up to several tens of pCi of natural radioactivity per gram, although some “hot” soils and rocks might contain millions of pCi (up to a few µCi per gram).

Radioactive materials are used extensively in the research laboratory – most labs use vials with small amounts of radioactive liquids and they will contain a milliCurie (mCi) – 37 MBq – of radioactivity or less. Higher levels of radioactivity – as much as a few hundred mCi – are used in nuclear medicine.

Radioactivity is also found in industry – low- to moderate-activity sources (on the order of a few to several mCi or a few hundred MBq) are used to help control various processes and sources of up to several curies (a few hundred GBq) are used by drilling companies to help them find hydrocarbons and water. Higher activities are used for industrial radiography – these sources, with up to a few hundred curies (a few to several TBq) can be deadly and, in fact, have caused death and injury in a number of nations. Any sources with tens of curies (hundreds of GBq) of activity or more must be considered dangerously radioactive.

Other sources can be even more radioactive – blood banks irradiate blood with sources that are several thousand curies (tens to a few hundred TBq), some research facilities use sources that can be tens of times as “hot,” while even higher levels of radioactivity are used in some specialty facilities. These sources can give a fatal exposure of radiation in a matter of minutes.

So – to try to give a sense of scale on these units….

Note: there is little controversy over the levels of each of these that are found in nature or what can be dangerous. The middle column (“Of interest”) is less well-defined – these are levels where I would start to think about taking protective actions, not to limit risk so much as to ensure  compliance with the appropriate regulations. Other health physicists likely have their own trigger points for each of these.

This posting is more of a tutorial than an explanation or opinion piece. I’d appreciate your feedback as to whether or not this is useful – if so I’ll post similar pieces from time to time as a change of pace.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Back to the Basics: Radiation Units appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

EMP mechanism

Some of you might remember a short-lived television series called Dark Angel, which aired on the Fox network for two seasons (2000-2002). The series’ backstory included the premise that a terrorist group set off a high-altitude nuclear burst that destroyed most of the United States’ electronic and communications infrastructure, plunging the nation into chaos. Recently, Republican presidential candidate Newt Gingrich has been voicing concerns that one of our enemies – presumably either a terrorist group or a rogue nuclear nation – might attack us in just this fashion and his speculations have raised a flurry of commentary (including this one, I guess). Before diving into the plausibility of such an attack, a bit of review on EMP might be in order, drawing upon an interesting discussion by Harvard Smithsonian Center for Astrophysics astrophysicist Yousaf Butt, who is also a scientific consultant to FAS, and a more technical description is found elsewhere on the FAS website. Going back a few decades, the National Academy of Sciences examined this matter in a 1984 report and came down between these two extremes.

The short version is that a nuclear blast generates a huge amount of radiation, and this radiation can strip electrons from atoms, creating ionization. The ions that are formed interact with the Earth’s magnetic field creating huge electrical currents and generating electromagnetic radiation. This, in turn, can induce electrical currents in conductors – pipes, wires, cables, and the like – and it is these currents that can fry electronic and electrical systems. According to Butt, “The exact value of the induced peak electric field depends upon the bomb yield, its design, and other factors already mentioned above, such as the detonation altitude, local magnetic field strength, and the geographic latitude of the explosion. Higher geomagnetic field strengths and higher latitudes (i.e. farther away from the equator, north or south) will typically create a stronger peak EMP field, other things being equal.” Butt also notes that, for high-energy bursts (100 kT and higher) the EMP will affect everything within the line of sight to the explosion. For a surface burst this would be several miles; a 100 kT explosion at an altitude of 500 km (about 300 miles) would be capable of blanketing the entire United States.

The effects of EMP have been documented – both American and Soviet nuclear weapons tests have knocked out power grids, street lights, and communications facilities hundreds of miles away, and these effects were not unanticipated by nuclear weapons scientists. So the bottom line is that Gingrich’s comments are not without a basis in both science and our experience. The question is that of plausibility rather than possibility, but the plausibility question is an important one. How likely is it that a terrorist group or a rogue nation will set off a 100 kT nuclear weapon at a high altitude over the United States in an effort to wipe out our electronics and plunge our nation into chaos? And to even start to address this we have to unfold this into its component questions:

Are there enemies who would like to see the United States slammed by such a blow? Almost certainly. There is no shortage of terrorist groups that have made no bones about wanting to hurt us as much as possible and who would likely love to strike such a blow against us. And not only terrorist groups – there are also nations (e.g. Iran, North Korea, maybe Venezuela, are a few) who would take some satisfaction in seeing the United States humbled.

If so, do “they” have the capability of making or obtaining a 100 kT nuclear device? Very few nations have the ability to produce their own nuclear weapons of any yield – besides the United States these are Britain, France, Russia, China, India, and Pakistan. Add to that list Israel (whose government has not declared it has nuclear weapons but it seems almost certain to possess) and South Africa (whose government gave up a nuclear weapons capability). North Korea has tested nuclear weapons, but both explosions were very low-yield; it’s not certain that North Korea can yet produce a 100 kT device.

If so, do “they” have the ability to loft it to an altitude of several hundred km over the US? Most of the nuclear powers have developed (or purchased) some ballistic missile capability, although not all of them have yet demonstrated the ability to reach the United States with their weapons. On the other hand, one can speculate endlessly about packing shorter-range missiles onto ships, assembling a weapon and delivery system in a nearer nation, and so forth. However, it seems less likely that a terrorist group will have such a capability.

If so, are “they” likely to use a nuclear weapon in this manner? This is the kicker – any missile launched arrives with a “return address” (its trajectory) that can be traced back to the point of origin. It is almost certain that we will know fairly precisely where a missile originated long before the pulse that would wipe out our electronics, and any nation would have to consider the possibility of nuclear (or non-nuclear) retaliation from ballistic missile submarines and from locations not affected by EMP.  Not only that, but nuclear-armed nations also have to contend with the possibility that nuclear forensics would be able to identify them as the source of fissionable materials should they donate or sell a weapon to a terrorist group. While we cannot rule out blind hatred or stupidity, enlightened self-interest and a strong sense of national preservation would suggest that the nations capable of attacking us would likely refrain.

This leaves terrorist groups, which (as far as we can tell) lack both nuclear weapons and missiles. This lack would seem to make a terrorist high-altitude nuclear attack unlikely. Even if a terrorist group were to develop its own nuclear weapon, going straight to a 100 kT device – about 8 times as powerful as the Hiroshima device and over 100 times as powerful as North Korea’s first attempt – seems as likely as Henry Ford’s first factory turning out a Prius. And even if a terrorist group were to come up with a 100 kT nuclear weapon we have to wonder if they would choose to set it off at high altitude and to forgo the imagery of a nuclear strike in the heart of a large city. All of these factors make me suspect that Gingrich’s scenario, while possible, it not likely very plausible.

If “they” do attack us, what will really happen? So let’s think about a few possibilities. Maybe the members of a terrorist group gets their hands on a nuclear device (any yield), but they set it off as a ground burst because they can’t reach a high altitude. Since EMP effects seem to be pretty much limited to line-of-sight, a single city and some of the suburbs might be knocked out but the entire nation would continue on as normal. But even taking the “Gingrich scenario” – assuming that someone launches a nuclear weapon 500 miles up – would we see the millions dead that Gingrich envisions?  Probably not.

A blast 300 miles up would no more kill people on the surface of the Earth any more than a blast in Washington DC would kill people in New York City. Of course there could be problems – especially if control systems are knocked out in airplanes, hospitals, and other places where even a short loss of “attention” by the electronics can be deadly. But aside from these obvious things it is far more likely that the loss of electronic systems would be a huge (and costly) inconvenience but it is hard to place credence in Gingrich’s projection of millions of lives lost. Our civilization predates the electronic age by centuries – our electronics make our lives more comfortable, more fulfilling, more efficient and so forth. But when the lights went out during the Northeast Blackout of 2003 civilization somehow managed to muddle along without massive loss of life.

Having said all of this it is easy to poo-poo Gingrich as being on a different plane of existence (and not necessarily a higher plane). As the above should make clear, I sincerely doubt that a terrorist group or a rogue nation is going to try to launch an EMP attack against the United States – not because it’s impossible but because it is unlikely. This is where we have to decide how (and whether) to prepare. If the outcome is so horrible that we simply cannot live with the results then we must prepare for this contingency, however unlikely – just as we prepared for both conventional and nuclear war with the Soviet Union. But if the cost of preparation is too high, the likelihood of such an attack is too low, and the possible negative effects are not too horrible then it might be unreasonable to give this matter an inordinate amount of attention.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post After the Pulse: Musings about EMP appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Societal risk reduction is the combination of many small details

One of my favorite movies is Ferris Buehler’s Day Off, and one of my favorite scenes is at the Art Institute of Chicago.  Beginning with a close-up of a bunch of dots of paint, the camera zooms out to show, first, a low-resolution face and, eventually, a painting (“Sunday Afternoon on the Island of La Grande Jatte,” by Georges Seurat, for those of you who always wondered – it still amazes me how quickly you can find this sort of stuff out through Google).  This is not a bad visual analogy for many things, but I’d like to think about it in terms of risk reduction.  Are we so focused on radiation safety and radiological risk reduction that we have lost sight of the larger picture?  In other words – are we concentrating on a dot and thinking it is the entire picture?

What brings this to mind right now are the continuing focus on Fukushima’s radiological impact and the cost to clean it up (and in the process paying scant attention to the thousands of dead and tens of thousands who lost their homes). Also relevant are a few consulting projects I’ve worked on, and some recent articles about the extraordinary measures people are taking to avoid even the slightest dose of radiation.  For example, would you believe that a dentist in the UK was sued for taking panoramic x-rays of some of his patients?  Nobody claimed to have been injured, but some patients were concerned about being put at needless risk. A few years ago the issue of irradiated gemstones – which have trivially small amounts of induced radioactivity – were an item of regulatory concern, forcing many to ask if there is any reason to think that irradiated gemstones should really be competing for our attention with far more potent radiation sources such as  irradiators, nuclear reactors, and orphaned sources.  Then there is the slew of articles discussing radiation dose to patients (including emergency room patients) from medical x-rays, and much more.

Now, I am not proposing that this attention is bad, and I am certainly not proposing that we drop the concept that we should try to keep radiation exposure as low as reasonably achievable (a regulatory concept called “ALARA”).  But I am proposing that we might try to expand the ALARA concept beyond the strictly radiological and try to think about what is reasonable when we consider all of the risks that are faced by an individual or by society.

Let’s take medical x-rays for example.  If I go to the doctor with a headache, I’m not sure that an x-ray is really called for – and almost certainly not a CT or fluoroscopy.  If my doctor sent me for one of these exams, I’d be interested in his explaining his reasoning to me.  On the other hand, when I showed up at the emergency room with severe abdominal pains I had no objections to the radiation dose from the abdominal CT used to determine whether or not I needed surgery. I felt the same way when my young son required x-rays to try to find out why he was having problems breathing.  Whatever risks a medical x-ray procedure may cause are not clinically significant at the time of the procedure; they may become clinically significant years or decades later, but only if the dose was high enough to initiate a cancer.  When faced with a gravely ill or seriously injured patient, shouldn’t the physician’s focus be the immediate well-being of the patient? Proceeding on a course of action without appropriate information is risky.  And these risks are immediate, not longer-term.  The bottom line is that not taking an x-ray also carries with it a risk – the risk of not having needed diagnostic information.  If this latter risk exceeds the risk from the radiation, then the physician should order the radiological procedure.

We can make similar comments about other aspects of radiation exposure.  It may make radiological sense to spend money cleaning up mildly contaminated sites.  But does it make sense for a society in which 1% of the population dies in traffic accidents to spend a lot of money in areas in which there is very little real risk reduction?  How can we justify spending money in areas that have little or no impact on public health, especially when that money is diverted from other areas that can have a real impact?  And when we consider that traffic accidents, childhood malnutrition and disease, shootings, and so forth affect both young and old, whereas cancer is primarily a risk to those of us who are older, it makes even less sense to be focusing excessively on radiological risks.  I am reminded of an oncologist I met in Cambodia who told me that, at that time, they only needed one radiation oncology clinic for the entire country – because so few Cambodians lived long enough to get cancer.  It made me realize that we in the developed world are fortunate that we live long enough to have the luxury of worrying about cancer.  It also made me realize that it makes sense to give everyone the opportunity to live long enough to develop cancer (or heart disease; no reason to play favorites) – by putting our risk reduction efforts into areas that kill young and old alike.  And this may mean reducing our emphasis on reducing radiological risks when the money spent can accomplish far more risk reduction in other areas.

Certainly we have to protect radiation workers and the population as a whole from the potentially adverse effects of radiation – the radiation safety profession and the regulations they follow serve a valuable purpose in doing this.  And we have an obligation to make sure that we do not abuse the environment unduly.  But let’s also remember that, after all of our best efforts, after all of the money that we spend, after all of the time that we devote to risk reduction, the sum of all of the risks in our lives remains 100% – reducing one risk necessarily increases all other risks because we are all going to die of something someday (I don’t want to sound overly somber, but there is no hiding from this fact). That being the case, shouldn’t we focus on the big picture– making sure that the largest number of people have the greatest opportunity to live into old age?  As members of society, shouldn’t this be our goal – to spend our society’s resources to the maximum benefit of everyone?  Yes – radiation safety and radiological dose reduction is a part of this picture.  But let’s remember that it is only one small part of a much larger picture – and that we cannot let our devotion to a single dot of paint overshadow our responsibility to the whole.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post The Big Picture: Keeping Radiation Risks in Perspective appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

In 1987, scrap metal scavengers in Goiania, Brazil, a city of about a million people, found a strange machine in an abandoned cancer clinic. Salvaging and dismantling the device, they found a small and enigmatic metal cylinder that aroused their curiosity – opening it up they found a fine blue powder. What they didn’t know was that the device was a cancer therapy machine, the cylinder was a radioactive source, and the powder was radioactive cesium. When all was said and done four people had received a fatal dose of radiation, over a hundred had received significant doses of radiation, and 249 needed decontamination. When news of the accident got out, about 112,000 people showed up at the soccer stadium to be surveyed – approximately 10% of the population.

Consider that number in terms of our major cities. Ten percent of the daytime population of New York City is a million people. Ten percent of our other major cities is hundreds of thousands of people seeking screening and reassurance that they have not been harmed by radiation or radioactivity. The CDC is promoting the concept of Community Reception Centers (CRCs) – something that has been a part of nuclear power plant emergency response planning for some time. 

Of course this assumes that these hundreds of thousands know to go to CRCs, which may not be the case. Even with CRC plans in place it is still a concern that hospitals might be overwhelmed by uninjured people who are worried about their health. This would not only take attention away from those who may badly need medical attention but can also delay the radiological surveys that the population so desperately wants because most hospitals simply are not set up to perform this level of screening.

For the uninjured person – contaminated or not – hospitals actually have little to offer. The best and fastest way to identify those who have skin contamination, or who have had an uptake of radioactive materials, is to have them scanned by trained responders wielding appropriate radiation survey instruments – exactly the sort of attention they will receive at an operating CRC.

At the same time, hospitals have an obligation to treat those who show up at their doors and many hospitals interpret this to mean that they cannot turn away even healthy people who are asking to be scanned for radiation. Ironically, trying to live up to this admirable interpretation of their obligation serves neither the hospitals nor those who desire screening – what is needed is a way to give hospitals permission in times of radiological emergency to redirect the “worried well” to radiological screening stations. This will free hospitals to carry on their core mission of treating the sick and injured, and will also route the public towards stations that can screen them more rapidly and more thoroughly for both external and internal radioactivity. By so doing both the injured and the concerned are better-served.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

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The post Serving the “Worried Well” Following a Radiological Emergency appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Projected first-year radiation dose from the Fukushima accident

This last April I traveled with two colleagues to Japan to help train physicians from the Tokushukai Medical Assistance Team (TMAT) - we gave a total of 8 lectures to over 1200 physicians and emergency responders during our visit, discussing how to safely care for patients who might have been exposed to radiation or who might be contaminated with radioactivity. A major reason that we were there was that the physicians simply were unfamiliar with the risks that the radiation posed to their patients or to them.

I thought it was a shame that so many Japanese physicians lacked what is really a fairly basic understanding of how radiation can affect a person. But it turns out that this lack of understanding is far more prevalent than this single incident in Japan. I helped to teach some medical school classes in the earliest years of this century and I was amazed to find that not only did my students not understand the effects of the medical radiation they were prescribing but they didn’t seem to care much. And when I asked for an hour of students’ time to teach them I was told by the medical school administration that there just wasn’t the time in the four-year curriculum to squeeze this in. Going further, surveys of radiologists in Australia, the United States and Great Britain  indicate that a majority of physicians do not understand the risks of the diagnostic radiation that they prescribe. Going a little further, there is anecdotal evidence (reported in the BBC Horizons documentary Nuclear Nightmares) that Soviet and European physicians advised over 100,000 women to have therapeutic abortions in the aftermath of the Chernobyl accident in spite of the fact that radiation dose to the fetus was insufficient to cause birth defects or other problems. The bottom line is that the majority of physicians – including radiologists and nuclear medicine physicians – are simply ill-informed about the medical and reproductive impact of radiation, be it from diagnostic procedures or from radiological and nuclear emergencies. This means that, in the event of a nuclear or radiological emergency in the United States, we can expect physicians to be similarly unable to offer competent medical advice or to perform competent medical triage in cases involving radiation exposure. This, in turn, has led (and can be expected to continue to lead) physicians to make unwise recommendations to their patients exposed to radiation.

Take one example – a physician confronted by a patient who is radioactively contaminated. In exercises (and in surveys) physicians tend to insist that such patients be decontaminated before even admitting them to the emergency room, in spite of the fact that experience is clear that such contamination poses no threat to medical caregivers – and in spite of the fact that delaying treatment can prove fatal to patients with life-threatening injuries. Returning briefly to reproductive effects – I have provided consultations to a few score of physicians whose pregnant patients received diagnostic radiation and who were wavering about recommending therapeutic abortions – in no cases was this called for. Unfortunately, physicians just don’t know much about the health effects of radiation – this causes problems today when pregnant women are exposed to diagnostic radiation and, if there is a radiological emergency, this can cause even more problems.

The apparent remedy for this would be to find a way to help train physicians – the way that my colleagues and I did in Japan a month and a half after the Fukushima reactor accident. Such training could not only help physicians to respond appropriately (and to provide proper medical advice) to their patients in the event of an accident or a terrorist attack, but could also help physicians today to better understand the impact of the radiation they prescribe and to give better advice to their patients who are exposed to radiation today.

One further comment – people tend to trust their physicians when it comes to health-related matters. Helping to educate physicians on the health effects of radiation exposure can also help to indirectly educate the general public about the health effects of radiation exposure under both routine and extraordinary circumstances – educating physicians might be a good way to help the public to better understand the reality (as opposed to the myths) of radiation’s health effects. This, in turn, could have a very real impact today as well as in the event of a radiological or nuclear emergency at some point in the future.

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Dr. Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Physicians and Radiation appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

Waiting for evacuation from the Fukushima area

Fight or flight is one of our most primal reflexes – faced with a potential danger we tend to turn one way to confront it or the other way to flee to safety. Fighting was not an option for the public in the aftermath of the accidents in Fukushima and Chernobyl – just as it is unlikely that the population of, say, New York City will head to the north if the Indian Point Nuclear Power Plant—about 35 miles north of Manhattan—suffers a problem (not to mention responding to an attack with a radiological weapon). The first impulse of the population is to try to get out of harm’s way, and the first impulse of the government is to try to move its citizens out of harm’s way. Let’s face it – if a cloud of radioactivity is heading towards you what can be more natural than to try to move yourself and your family out of the way? People tend to self-evacuate – who can forget the pictures of people streaming over the Brooklyn Bridge after the September 11 attacks? – and governments tend to want to evacuate those left behind.

The problem is that evacuation is not always the answer and evacuation is not a risk-free event. There are times when trying to move yourself – or your citizens – out of harm’s way is actually riskier than leaving them in place.

Consider – virtually all of New York City’s people live within 50 miles of the Indian Point Nuclear Power Plant and the northern-most part of Bronx lies about 25 miles away. Evacuating 10 million people to “safety” would mean driving them into New Jersey, Connecticut, or into eastern Long Island. So say we put 10 million people on the road and try to move them 50 miles – that’s about 500 million person-miles of driving. The risk from driving varies according to where you live but they are not trivial – if we assume a low value of 2 deaths per 100 million passenger-miles then 10 people would be expected to die evacuating New York City – more if even a single bus overturns, as has happened several times in the last year alone. Whether the actual number would be higher (due to people driving poorly and panicking) or lower (due to slow speeds on clogged highways) we can’t guess. But the bottom line is that there is a very real risk from evacuation and it behooves us to try to determine whether the risk from evacuation is higher or lower than the risk from a radioactive plume.

Indian Point published multiple studies of radiation dose to the population from a variety of accident scenarios – reviewing these studies suggests that radiation dose to people who remain in New York City would be too low to cause any demonstrable health problems to the population. In fact, the radiation dose to the average New Yorker would be comparable to a few x-rays – not nothing, but well within the natural variability we are exposed to as we travel from place to place on Earth. If we assume that traffic statistics are applicable in an emergency evacuation then it is likely that a forced evacuation would save no lives and might actually increase the risks to the population of the city. In other words, our instincts might serve us poorly.

Interestingly, immediate evacuation might not make much sense in the case of a nuclear or radiological attack either. Radiation dose in the fallout plume from a terrorist nuclear attack might be rapidly fatal while moving indoors can cut this dose to levels that are easily survivable. So, picture yourself standing in Maryland and seeing a nuclear detonation over Washington, DC and realizing that the wind is blowing your way. Fleeing is a natural reflex –for you and for about a million of your fellow citizens. Of course you need to get out of the plume – if you simply try to drive directly away from the source of the explosion you’ll be driving down the axis of the plume and receiving a huge radiation dose; driving perpendicular to the plume axis is a better bet, but even here you have to be assured of clearing the area before the plume touches down. On the other hand, if you go indoors – preferably into a basement or into the core of a large building – you are likely to receive a fairly low dose of radiation that will almost certainly be survivable. In fact, according to some U.S. government estimates, going indoors immediately (rather than immediate evacuation) can save up to a half million lives in some cities. The moral of the story is that evacuation can be deadly and hunkering down can save your life.

We saw this in Japan, by the way. I was in the Fukushima area a month or so after the accident and my radiation measurements (which were consistent with those reported by the IAEA, the Japanese government, and the US government) showed that radiation levels posed no short-term risk and only a minimal long-term risk. By comparison, news sources reported that nearly 50 patients died of exposure, dehydration, and other causes during hospital evacuations from the affected area. Similarly, the World Health Organization concluded in a 20-year follow-up study (http://www.who.int/mediacentre/news/releases/2005/pr38/en/index.html provides a summary statement and the report can be downloaded at http://www.who.int/ionizing_radiation/chernobyl/assessment_mitigation/en/index.html) that mental health issues – stemming in part from the forced evacuation of over 330,000 people – were by far the biggest health concern facing those removed from the exclusion zone. And to round out this discussion, it also makes sense to go indoors if an RDD goes off – to shelter from the radioactivity and to stay out of the way of the emergency responders (unless, of course, your building is on fire or is in danger of collapse).

There are many disasters for which evacuation makes sense – and the sooner the better. But for a radiological or nuclear accident it could be that our fight-or-flight reflex serves us badly. Sometimes sitting and doing nothing makes more sense – and saves lives.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Fight, Flight, or Freeze: Response Options to Nuclear or Radiological Emergencies appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

A laboratory-created version of the 1918 influenza virus

Where is the borderline between freedom of inquiry and national security? Between the freedom to pursue – and publish – scientific results and the fear that these published results might be used to horrific effect? Or put another way, are there some lines of scientific inquiry that simply should not be undertaken at all because they are too dangerous, or that – once undertaken – should be withheld from publication?

The decision to develop nuclear weapons is a case in point – the need to develop these weapons seemed urgent, given indications that Germany was working towards the same end. Given the choice between a Nazi bomb and an Allied weapon the United States, Canada, and Britain chose to pursue these weapons with the results we all know. But after the war there was a choice – some Manhattan Project scientists felt that the safest way to use this knowledge was to make it freely available to everyone while others (and the government) saw these weapons as a possible threat to our nation’s survival and chose to lock the information away.

In hindsight it seems likely that nuclear weapons did not affect who won the Second World War – the German nuclear weapons program never made much progress and Japan would almost certainly have fallen with or without their use. The weapons almost certainly shortened the war but they did not change the ultimate outcome. Given this it is reasonable to ask if our Manhattan Project scientists might have better served humanity by simply refusing to do the work requested, or by working but deliberately not solving the problems they faced.

Tempting as it is to speculate that, absent the success of the Manhattan Project, the world would not have known the threat of nuclear explosions, such speculation is likely wrong – by the mid-1940s all of the basic science and the fundamental concepts were well-known. That being the case – and especially given the tensions of the nascent Cold War – it is almost certain that both the United States and the Soviet Union would have developed nuclear weapons within a few years of the war’s end. In 1992, I was present at an interview that Edward Teller gave to a Columbus, Ohio television station (sorry, can’t remember which one) in which he justified his leading the effort to develop thermonuclear weapons by the fact that the Soviets were working on them. Teller opined that such weapons were bound to be built and, that being the case (and given our opponent) far better for them to be developed first by the United States.

This decision may or may not have contributed to national security – we know that the Soviet Union embedded spies in the Manhattan Project during the development of both nuclear and thermonuclear weapons and that Soviet bomb developments lagged the American weapons by only a few years. But the information on how to develop nuclear weapons seeped out over the following decades – at present the big-picture details of how to build nuclear weapons are hardly a secret, although the fine points remain closely held secrets of the nuclear-capable nations.

For decades the world lived with the possibility of a civilization-ending nuclear war and it is hard to know if sharing nuclear weapons technology feely would have changed this for the better or for the worse. But this is a moot point because we have the world that was made over a half-century ago. On the other hand, in different fields, this question arises from time to time with a possible impact that could be every bit as consequential as the decision to pursue nuclear weapons.

Consider for example recent research by Dutch virologist Ron Fouchier reported in the journal Science. Fouchier and his team tinkered with an avian flu virus – H5N1 – in such a way that has the potential to make this not only deadly but also more infectious. An article in the November 23, 2011 edition of ScienceInsider quotes Paul Keim, a microbial geneticist who chairs the National Science Advisory Board for Biosecurity as saying that he “can’t think of another pathogenic organisms that is as scary as this one…I don’t think anthrax is scary at all compared to this.”

So the question is what to do about research such as this – a question with tremendous ethical implications no matter how you look at it.

• Is some research just too dangerous to undertake – should we (can we) purposely stifle some lines of inquiry?
• Should scientists refrain from undertaking research that can have such potentially devastating consequences?
• Should governments restrict this line of work so that it only takes place under the control of government scientists (and do we trust the governments to be the sole repositories of the fruits of such work)?
• If this work is done, should the information be made freely available to everyone with a subscription to the scientific literature or should it remain locked up by governmental secrecy rules?

There is a good reason that the very first amendment to the Constitution grants the freedom of speech – this freedom was considered essential to the proper functioning of any free society. In case after case the Supreme Court has upheld the freedom of speech, even when it includes burning the flag, publishing pornography, and contributing money to political campaigns. One can envision freedom of inquiry – including scientific inquiry – as being another form of freedom of speech and it seems reasonable to assume that this freedom of inquiry should be extended as far as possible. Obviously, the American Constitution cannot be applied to a Dutch citizen, but it does apply to the publishers of Science (an American journal), and it is worth discussing as a philosophical point in any event.

What is interesting is that, even in one of the most vital parts of our Constitution, the Supreme Court has carved out some exceptions. The most famous of these is that shouting “Fire” in a crowded movie theater is not considered constitutionally protected free speech, just as some forms of hateful speech or speech that incites others to violence is similarly off limits – in other words, we are not free to speak if that speech serves only to put others at risk.

So let’s think more about not only Fouchier’s research but about other similar work that we have seen in the past and are likely to increasingly see in coming years. Modifying a lethal virus to make it even more lethal – is this the equivalent of shouting “Fire” that serves no useful purpose other than to place people at risk, or is it something that should be protected?

Of course there is more to it than this – like with the science behind nuclear weapons, all of the basic science and techniques for modifying viruses are “out there” and the number of people who know how to use this science grows every year. It is silly to think that stifling Fouchier’s work will put a global halt to this research. Chances are that, even if Fouchier (and others around the world working on related research) stop their work it will simply be taken up by somebody else – possibly working more secretly. On the other hand, it is also possible that withholding publication of his results might delay this other work by several years, perhaps giving us the time to develop an effective vaccine against a bug that could kill many millions if it breaks out as an easily transmissible epidemic.

There is no easy answer to this question – for every argument in any direction there is a counter-argument. For example, we can argue that this work is too dangerous to be undertaken at all because the potential cost is too high; but we can counter-argue that this work will be undertaken by somebody. We can argue that publication should be suppressed to avoid giving a possible weapon to our enemies (the bad guys, of course!); but we can counter-argue that, given the near-inevitably of such research taking place, at least this way we can keep track of those working on it. Some of these issues are discussed in an interesting paper by Ronald Atlas, published in the March 3, 2006 issue of Science and Engineering Ethics titled Responsible Conduct by Life Scientists in an Age of Terrorism and a companion paper (The Dual-Use Dilemma for the Life Science: Perspectives, Conundrums, and Global Solutions, published in the September 25, 2006 issue of  Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science) Atlas suggests that such information should be freely available to the global scientific community, but urges a “culture of responsible conduct” on the part of life scientists to minimize the chances that such work might be “hijacked for hostile misuse” by terrorists or irresponsible and hostile nations.

Again – there is no easy answer but, given that this sort of topic seems to arise fairly regularly (the publication of the 1918 influenza genome and work done by Australian scientists Samantha Robbins and several colleagues to help viruses evade the immune system to name just two), perhaps we should try to come up with the difficult answer.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Breeding better bugs? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

By Dr. Y

Every now and again plutonium makes the news. Traces of it were found in Japan after the Fukushima reactor accident in early 2011, traces were found in some uranium enrichment facilities in 1999, plutonium-contaminated lands were engulfed in wildfires near national laboratory facilities several times in the 1990s and 2000s, and a laboratory worker at the National Institute of Standards and Technology was exposed to small levels of plutonium in 2008 – not to mention an entire book (The Plutonium Files) that was written about human plutonium experiments carried out in the first decades of the atomic age. It seems that every time the issue of plutonium arises there are similar concerns – that plutonium is uniquely deadly (usually using the phrase “the most deadly substance known to humanity”), that plutonium is not found in nature, and that the plutonium found near the Fukushima reactors could only have come from ruptured reactor fuel disseminated into the environment. Each of these points is flawed – here’s why.

The most toxic substance known?

Contrary to popular opinion, plutonium is far from being the most toxic substance known. True – it is a radioactive and toxic heavy metal, as are lead, uranium, mercury, and cadmium (to name only a few). It is also true that plutonium is highly toxic – a fraction of a microgram can kill, but the deadliness comes from the radiotoxicity more than from the chemical properties of the element. But polonium – such as what was used to kill Alexander Litvenenko in London in 2006 – is far more radiotoxic, and any number of organic poisons, including ricin, botulism toxin, some spider venoms, amatoxin (found in poisonous mushrooms) and some shellfish toxins are also far deadlier than plutonium.

Ironically, the book The Plutonium Files helps to make this point that plutonium is not uniquely toxic – the author mentions a number of experiments in which subjects who were thought to have only days or weeks to live were injected with plutonium for purposes of scientific research and that many of these people were still alive decades later, having been exposed to the injected plutonium far longer than expected. What the author did not comment on was that this very longevity suggests that trace amounts of plutonium are not deadly – were that the case these subjects would have succumbed from plutonium toxicity. Putting all of this together – yes, plutonium is highly toxic but no, it is far less toxic than many natural venoms and toxins.

Plutonium artificiality

The first plutonium that was identified was produced in nuclear reactors and, in fact, the Manhattan Project put a huge effort into producing even the first few micrograms of plutonium and an even greater effort into making the kilogram quantities needed to produce the weapon that was dropped on Nagasaki Japan in August, 1945. In nuclear reactors plutonium is produced within a few days after the nucleus in the uranium-238 atom captures a neutron, transforming it into U-239. This then undergoes radioactive decay and becomes Np-239, which soon undergoes another radioactive decay to become, Pu-239, a fissionable nuclide that can be used to make nuclear weapons.

Surprisingly, this happens in nature as well, most often in uranium ore deposits. The surface of the Earth is subject to a continual neutron flux caused by cosmic ray interactions in the atmosphere – these neutrons can be captured by U-238 (which makes up over 99% of natural uranium atoms), producing U-239 and, thence, Pu-239. In addition, U-238 is a large atom that sometimes fissions spontaneously, emitting neutrons that can be captured by neighboring atoms with the same result. The first natural plutonium was identified in uranium ore by Charles Levine and Glenn Seaborg in 1951. Further, in 1967 geochemist P.K. Kuroda also identified the remnants of Pu-244 in meteorites, apparently produced by supernovae in distant parts of the galaxy (http://www.terrapub.co.jp/journals/GJ/pdf/2601/26010001.PDF). It is safe to say that large quantities of plutonium on Earth are bound to be man-made, but trace amounts of plutonium are produced in nature as well.

Plutonium from reactor fuel

As mentioned above plutonium is produced in nuclear reactor fuel – in fact, a substantial fraction of the energy produced in a nuclear reactor comes from the fission of plutonium produced during normal reactor operations. But the fact that plutonium was found near the Fukushima reactors does not mean that it came from them. In actuality there is plutonium found in all of the soils of the Earth. Some of this plutonium comes from nuclear weapons testing – only a fraction of the plutonium in the warheads fissions and the remainder is thrown into the atmosphere, settling back to Earth gradually over the following years. Then there was a plutonium-powered satellite that was incinerated in the atmosphere in 1967 – plutonium from that spread across the planet as well.

Plutonium is a refractory element that is locked up within the reactor fuel – even during a fuel meltdown it is not easy to spread the plutonium far afield. This is not to say that there have not been reports of plutonium from the damaged reactors – an article in the October 2, 2011 Financial Times (http://www.ft.com/cms/s/0/7e3af460-ece6-11e0-be97-00144feab49a.html#axzz1eI6gJlxa) reports that traces of plutonium from the reactor were found up to 40 km distant. What is difficult is trying to untangle the plutonium that we expect to see from the sources mentioned in the first paragraph from those that came from the reactors – any short-lived isotopes of plutonium (especially Pu-241) is more likely to have originated in the reactors while the longer-lived nuclides (Pu-238, Pu-239 primarily) may have its origins in the era of atmospheric nuclear weapons testing.

The bottom line is that plutonium can be nasty stuff – especially when used as a nuclear explosive. But we should give it the respect it is due – neither short-changing its dangers nor exaggerating its threat. Only by so doing can we take reasonable steps to assure our safety.

Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post About that Plutonium appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

By Dr. Y

It’s no secret that security in our airports has changed dramatically in the last decade and, whether we think these changes are effective (or needed) or not many of them are here to stay. One of the technologies that has come into vogue recently uses what are called backscatter x-rays to help airport security to see if a traveler is hiding weapons or explosives beneath his or her clothes without the time and indignity of a strip search. But these machines have become highly controversial, partly for reasons of personal privacy (they can produce images of the body that are a bit more detailed than many people feel comfortable with) and also because the exposed passengers to radiation. It was this latter aspect that was the subject of a story on National Public Radio’s “Talk of the Nation – Science Friday” show on November 19, 2010 .

Before getting into the show it might be useful to understand a little bit about how the machines work. Backscatter x-rays (unlike normal x-rays, which pass through an object) are reflected off an object and back into the scanner – this happens because they have too little energy to pass through an object. In practical terms this means that the skin is exposed to the highest dose of radiation and the internal organs receive very little. How much dose? I measured the output of a backscatter x-ray machine and the radiation exposure was on the order of a few hundred micro-rem. To put this in perspective, we are all exposed to natural radiation every day of our lives, to the tune of about 20 micro-rem (give or take a little) every hour – a single backscatter x-ray image, then, exposes us to the equivalent of perhaps a half-day or so of natural background radiation. The flight also exposes us to radiation – on a recent trip to Japan I picked up 6000 micro-rem (or 6 milli-rem (mrem) on each flight. So a frequent flyer might pick up several tens of mrem in a year from backscatter x-ray examinations. The question is whether or not this poses an unacceptable health risk to frequent flyers – this is the topic being debated.

We are normally exposed to about 300 mrem a year from natural sources, but there is tremendous variability in this dose – when I was in the Iranian spa city of Ramsar in the year 2000 I measured radiation dose rates of up to 2500 micro-rem (2.5 mrem) per hour and some of the residents receive as much as 100 times the background radiation exposure that we see on average here in the United States. In spite of this the residents of Ramsar do not seem to develop cancer more readily than do residents of nearby areas . Similarly, residents of high-background radiation areas in Kerala, India and Guapari, Brazil seem to have no greater incidence of cancer  than do the residents of nearby areas with normal radiation levels. In fact, in the United States, the Rocky Mountain states (that have the highest natural radiation levels) experience lower rates of cancer than do the lower-dose rate Gulf Coast states. What all of this is getting at is that our experience with variations in natural radiation seems to suggest that elevated – but low – levels of radiation do not seem to affect the health of those in those areas. Having said that, there is a huge debate among the world’s radiation scientists as to whether or not low levels of radiation – such as those to which we might be exposed during backscatter (or normal medical) x-ray examinations. Which brings us back to the November 19^th Science Friday….

One of the show’s guests, Columbia University radiation biologist Dr. David Brenner, made the point that, although every individual dose is low, exposing hundreds of millions of air travelers to this exposure every year is likely to cause some of them to get cancer. If, say, 100 million travelers are exposed to 100 micro-rem from each of these scans then the total radiation exposure to these people will come out to 10,000 person-rem of exposure among the traveling population – enough to induce a fatal cancer in five people. This is a concept that is called “collective dose.” The problem is that Brenner’s conception of the risks from collective dose runs afoul of the recommendations of major national and international advisory bodies – the Health Physics Society and the International Council on Radiation Protection (ICRP).

Let’s start with the Health Physics Society’s 2010 position paper, Radiation Risk in Perspective. According to this paper, “In accordance with current knowledge of radiation health risks, the Health Physics Society recommends against quantitative estimation of health risks below an individual dose of 5 rem in one year or a lifetime dose of 10 rem above that received from natural sources.” Radiation exposure from backscatter x-ray machines clearly falls into this category for each traveler. According to the Health Physics Society – one of the world’s pre-eminent radiation safety organizations – it is simply not appropriate to calculate risks and possible cancer deaths from this level of exposure because the dose is so low that “risks of health effects are either too small to be observed or are nonexistent.”

While the Health Physics Society has looked at the effects of exposure to relatively low doses of radiation, the ICRP has looked at the impact of collective dose to large numbers of people.  In a 1999 paper published in the Journal of Radiological Protection  Roger Clarke (then-chairman of the ICRP) noted that individual radiation doses on the order of a few mrem (in SI units, a few tens of micro-Sieverts) pose a “trivial” risk to the individual. Clarke goes on to suggest that doses of this magnitude are “so low as to be beneath regulatory concern” and that “if the most exposed representative individual is sufficiently protected from a given source, then everyone else is also sufficiently protected from that source.” Clarke also makes the point in this paper that “If the risk of harm to the health of the most exposed individual is trivial, then the total risk is trivial – irrespective of how many people are exposed.” An analogy  might be in order – if I throw a 1-gram rock at each person in New York City the cumulative weight is about 10 tons – enough to crush a lot of people. Brenner would have us looking for bodies; Clarke’s position is that nobody will be crushed because even 10 million small rocks – each tossed at a different person – aren’t going to hurt anyone. Similarly, Clarke’s position is that it is highly likely that even exposing a billion travelers to a vanishingly small dose of radiation is not going to hurt anyone because every individual exposure is “trivial.”

But (I hear you ask!) what about the cumulative dose – if a person is exposed to a few hundred of these backscatter x-rays every year, then the dose over the course of the year exceeds what Clarke (and the ICRP) consider to be a trivial dose.  After all, if we pile 10 million small rocks on top of a single person it will likely do some damage – perhaps x-rays work the same way. That might be true if the x-rays come in quick succession but, in practice, most of us pass through security one day and back through a few days (or weeks) later. Since our bodies produce DNA repair proteins that ramp up following identification of genetic damage (an effect called adaptive response) a single backscatter x-ray might cause minor amount of damage that will be fairly quickly repaired. A frequent traveler is looking at, say, a hundred or so individual trivial exposures in a year rather than the equivalent of a single higher exposure. So, the Health Physics Society tells us that it is scientifically inappropriate to calculate the risks from any exposures of less than 10 rem and Clarke (and the ICRP) suggest that a large number of “trivial” exposures do not add up to a significant population dose. Both of these positions are contrary to the suggestion that backscatter x-rays might cause a public health hazard.

Brenner is a distinguished and respected radiation biologist, and it is not easy to disagree with him on this point. An eminent health physicist, Argentina’s Daniel Beninson, commented in his 1996 Sievert Award lecture that the inability to “see” a health effect does not mean that it does not exist. But science is a field that makes predictions that can be tested and falsified – any putative risk from exposure to 100 mrem is far too small to be detected via epidemiological studies of the affected populations and the hypothesis that this harm is taking place cannot be tested and cannot be falsified. As such, until our epidemiological tools improve, such speculations are intriguing but may not be scientific because of this lack of falsifiability – they represent a belief or even a philosophy rather than a scientific position. We must keep this in mind when we are comparing the risks (privacy and health) of undergoing backscatter x-ray exposure against the risks these examinations are intended to avert.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety.

The post Are airport scanners safe? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.

The last years have seen an increasing number of observations showing that Mars once had liquid water and that it has ice not far underground today. In the 36 years since the equivocal results of the Viking probes’ search for life space scientists have scaled back their experiments, looking instead for evidence that water once flowed on the red planet as well as evidence of ice at the poles and beneath the surface dust and sand. Most recently, just last week (December 8, 2011) the Mars Opportunity rover returned what NASA calls a “slam dunk” – a vein of gypsum, a mineral that incorporates water into its crystal structure. Absent water, gypsum cannot form.

Four decades ago the Mariner 9 spacecraft returned photos of what seemed almost certain to have once been the beds of ancient rivers and many more such features showed up in photos taken by later orbiting craft. Later, more sophisticated craft (the Mars Global Surveyor once returned spectrographic evidence of minerals on the Martian surface that, on Earth, are formed only in the presence of water. All of this evidence has grown only stronger with time, including photos suggesting that liquid water might still flow today at rare times of the year. But photos and information obtained from orbit are one thing – indirect evidence – having direct information from the surface is something else entirely.

More recent spacecraft have provided us with just such evidence – recent Mars landers have returned photos of stones that appear to have been tumbled in running water, as one example. But even more telling were the discoveries of minerals such as some clay minerals, and the very recent identification of gypsum. As a graduate student studying under the renowned geochemist Gunter Faure, I learned that minerals such as these include water molecules incorporated into their crystal structure and that, on Earth, they are not formed except in watery environments – their very presence tells us that water almost certainly existed on Mars at the time these minerals formed.

And there is even stronger evidence – in 2008 the Phoenix lander descended to the Martin surface atop the blast of landing rockets. These rockets blew away the topmost layers of soil, revealing bright patches that are now known to be water ice. All of this evidence – orbital photos, the presence of hydrous minerals, and the discovery of ice hiding just between the surface layer of dust and soil – points unambiguously to the presence of water ice on Mars today, and it raises the possibility that Mars might once have hosted (and perhaps still does host) living organisms. And liquid water might exist in more places in our Solar System than just Mars – there is ample evidence that oceans of water might exist in the outer Solar System as well, not to mention the recent discovery of an extra-Solar planet in its star’s “Goldilocks Zone” where temperatures should permit liquid water to exist on the planet’s surface.

All of this makes it seem likely that liquid water is not uncommon in the universe and, that being the case, it makes it even more likely that we will find an ever-increasing number of planets that might be able to host life as we know it. This is exciting, but it is also very limiting – very water-chauvinistic. Water is useful to terrestrial life because it is a great solvent and it does a great job of carrying in solution the ions and molecules that help to sustain life. But other liquids can serve this same purpose. In mid-2011 I was lucky enough to interview astrophysicist Neil deGrasse Tyson, Director of the Rose Center for Earth and Space at the American Museum of Natural History in New York City for a book I was writing. Tyson pointed out that liquid methane can serve as the foundation of life in a cryogenic environment, as can other liquid hydrocarbons (he also pointed out that, for all that we consider life’s diversity, all Earthly life is based on water and DNA, which might seem frightfully limited to organisms elsewhere in the universe). It might be that our paradigm of the requirements for life should be less restrictive than looking for water; rather, perhaps we should consider that any liquid solvent might serve as the basis for life. This not only broadens the environments in which we might search for life, but also makes things more complex – would we even recognize living organisms whose biochemistry was based on something other than water and DNA?

There is even more to it than this – much of what we consider to be vital to the evolution of life could well be simply our speculating about life when (as Tyson points out) we have a sample size of 1: Earth. University of Washington scientists Peter Ward and Donald Brownlee published a book (Rare Earth: Why Complex Life is Uncommon in the Universe) over a decade ago in which they made a compelling case that the rise of complex life on Earth required the Earth to be in the Solar System’s habitable zone, for the Solar System to be in the Galactic habitable zone, for the Earth to have an unusually large moon, and a number of other factors. Brownlee and Ward did a wonderful job of explaining why these factors might have contributed to the rise of complex life (including humanity), but their view – however well-reasoned – falls prey to the same degree of chauvinism that Tyson decried. We simply cannot assume that, just because the only planet known to have life has these characteristics that they are essential to life everywhere in the universe. After all, it was once thought that all earthly life depended directly or indirectly on the Sun, until the Alvin submersible discovered extensive ecosystems around deep-sea hydrothermal vents that are utterly divorced from the Sun as a source of energy.

Humanity has been considering the possibility of life elsewhere in the universe for millennia – not just science fiction writers but philosophers, scientists, and theologians as well. Think of the irony of finding – and looking right past – living organisms simply because they don’t conform to our expectations.

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Dr Y is a certified health physicist, trained in nuclear power plant design and operations, with experience in nuclear power, environmental science, and planning for radiological and nuclear emergencies. He has 30 years of experience in the areas of nuclear and radiation safety (and, relevant to this piece) both BA and MS degrees in the Geological Sciences).

The post Water on Mars? appears on ScienceWonk, FAS's blog for opinions from guest experts and leaders.