BRAWM team - Some interesting "hot particle" info

Thanks for this! This brings up a whole lot of excellent points.

#1. We do have a very good idea of what isotopes were produced inside the reactors. The standard tool for this has been ORIGEN, a computer code produced by Oak Ridge National Lab. It's not terribly easy to use, but we have a group in our department that specializes in this work. They know the details regarding how much fuel was used, its geometry, its burn-up schedule, and many more things, and can predict all the isotopes and how much would have been in each reactor. The ratios of the various isotopes that we measured (cesium, iodine, and tellurium) match extremely well to the ratios predicted by the ORIGEN calculations, so we're pretty confident about what was inside.

That said, we only know the amounts that were inside, not how much was released from containment. The isotopes we saw were the more volatile ones, not ones like plutonium. However, if we did see plutonium, we know the exact isotopes that we would find, and could confirm whether or not they came from Fukushima. This is similar to what you can see in this TEPCO report, where they compared the measured plutonium, americium, and curium to ORIGEN code and confirmed that the isotopes found were indeed from the reactor.

#2. Those papers you linked to were pretty interesting -- sorry you couldn't access them (if you could go to a college campus and use a computer, perhaps?). They did gamma spectroscopy with germanium detectors to meaasure Cs-137, basically the exact same setup we used. For plutonium, both studies used alpha spectroscopy, which we were trying to do, but they had much more advanced chemical processing, which is why they had much better results than us. This is the standard way to find plutonium, and it appears to be a very different method than what Marco Kaltofen was doing, which is why we couldn't confirm much about his results.

I wanted to clarify the state of all these plutonium claims: We have been often repeating "the EPA did not find plutonium," which is true. We aren't saying that there is no plutonium anywhere, and I think those papers are a great reminder of the ubiquitous plutonium released during our above ground tests (note that these were from around the Nevada test site, and so were easier to find). This is distinct, however, from the EPA results, which were negatives. As to WPI's work, I can't say either way, since I haven't seen their results, but it appears their experiment cannot distinguish between isotopes, so there's no obvious way to say where the material came from.

Tim [BRAWM Team Member]