Radioactive waste disposal is not cheap. When I was a radiation safety officer we spent $10,000 each year to dispose of a fairly small amount of waste, and a few years our disposal bill was closer to $50,000. At another university I worked at we spent over a half million dollars to get rid of about 3000 cubic feet of radioactive waste that had been accumulating for a decade or so. Not a fortune, but this was a number of years ago. More recently I had a consulting client who paid over $100,000 to dispose of waste from three relatively small (10’x10’x5’) storage tanks – on top of the money spent to characterize the site and to analyze the waste. Now – think of how much radioactive waste will be produced in the aftermath of a dirty bomb attack, and how much it might cost for disposal. But unless we have some sort of disposal plan made up in advance we might find ourselves trying to figure out not only where to dispose of the waste, but even where to stage it in the short term while awaiting permanent disposal. And that doesn’t even get into the fact that the cleanup standards we choose can have a profound impact on the amount of radioactive waste generated. Let’s tackle that last topic first because it’s sort of a fundamental point. Right now there are no published cleanup standards for a city hit with a radiological terrorist attack. There are standards for radiological cleanup – it’s just that these standards are designed for routine use and they’re based on our technological ability to detect the presence of radioactivity rather than on the risk that is posed by that radioactivity. It’s sort of like saying that, since dropping a 100-pound rock on my head will be harmful, we’re going to control every grain of sand large enough for me to see. Sure – this will make sure that nobody gets a rock dropped on them, but it’s a bit on the conservative side.
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.