The last few weeks have brought a little more information about the radioactive tissue boxes I wrote about in an earlier posting. Since this topic is important and because it raises interesting issues it’s worth an update, so here goes.
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.
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