by Matthew Payne on November 3, 2011Comments Off
So, what has long been suspected has been confirmed. Nature News is reporting that a study to be published by Atmospheric Chemistry and Physics argues that Fukushima produced far more radioactive fallout than has been reported. According to the principal researcher, the Norwegian atmospheric scientist Andreas Stohl, Fukushima released much more radiation than the Japanese government is reporting, but much of that radiation is of isotopes of Xenon rather than Cesium (this is important since Cesium is far more easily absorbed by the body). The key findings:
The latest report from the Japanese government, published in June, says that the plant released 1.5 × 1016 bequerels of cesium-137, an isotope with a 30-year half-life that is responsible for most of the long-term contamination from the plant2. A far larger amount of xenon-133, 1.1 × 1019 Bq, was released, according to official government estimates.
The new study challenges those numbers. On the basis of its reconstructions, the team claims that the accident released around 1.7 × 1019 Bq of xenon-133, greater than the estimated total radioactive release of 1.4 × 1019 Bq from Chernobyl. The fact that three reactors exploded in the Fukushima accident accounts for the huge xenon tally, says De Geer.
Xenon-133 does not pose serious health risks because it is not absorbed by the body or the environment. Cesium-137 fallout, however, is a much greater concern because it will linger in the environment for decades. The new model shows that Fukushima released 3.5 × 1016 Bq cesium-137, roughly twice the official government figure, and half the release from Chernobyl.
The real news here, I would argue, is not a somewhat meaningless award for which nuclear disaster was the greatest FUBAR of all time, but the much larger releases of Cesium than previously estimated. While the Norwegian team is rightfully cautious about its findings (“If you look at the estimates for Chernobyl, you still have a large uncertainty 25 years later,” says Stohl), their methodology is much more sophisticated than the Japanese government’s approach because they are taking advantage of the radiation monitoring equipment set up by the Comprehensive Nuclear-Test-Ban Treaty Organization, while the Japanese scientists have been relying on land-based monitoring. As the below map shows, this is a problem since much of the radiation in the crucial period when the Unit 4 fuel pool was burning was sent out to sea (later to be blown back inland).
One doesn’t have to imagine a conspiracy here, since the Japanese scientists genuinely disagree with the Norwegians on the effect of the burning of spent fuel rods in Unit 4. Basically the Japanese do not think this event released much radioactivity; the Norwegian team, however, points to the spiking of Cesium-137 (very carcinogenic, for those inquiring minds) that suddenly ended once, you know, TEPCo decided to poor water on those fuel rods. So, the Norwegians call bullshit on the whole, “burning fuel rods, no big deal” approach. I call bullshit too. Three reactor meltdowns is anybody’s notion of a bad day. Three meltdowns with burning spent fuel rods and your corporate leadership dithering, well that is epic fail. These Norwegian fellows had much more data to work with than the Japanese (and by the way, why is that? Doesn’t the IAEA care to measure radioactive isotopes in the Jet Stream?) and their conclusions are consistent with what we know happened in March. And, for added special irony, had someone actually poured water on the spent fuel rod pool when it started to burn, most of the Cesium would not have been released. Horse. Barn door.
So, what does this all mean? Well, French nuclear scientists have estimated that 27.1 thousand terabecquerels of Cesium-137 have been released by Fukushima, a mere 20-fold increase to what TEPCo is copping to. Cesium-137 has a half-life of 30 years and is highly carcinogenic–in other words, Fukushima will be the poisoned gift that will keep on giving for a long time in Japan. A long time.
Oh, and by the way, Unit 2 is still, in all likelihood, fissioning. The tell-tale signs of radioactive Xenon and the fact that TEPCo rushed to inject boric acid into the cottage cheese that was once a nuclear pile in Unit 2 is, as they say, not good. The reactor fissioning does not mean that it goes boom, like Hiroshima; a nuclear pile is supposed to fission, that’s how it boils water. But a nuclear pile that is fissioning with no meaningful containment is likely spewing radioactivity. Since the isotopes of Xenon measured have a brief half-life of nine hours, whatever the pile was doing it was doing very recently. The word for all this is “recriticality” and “recriticality” is not your friend when you are trying to achieve a cold shutdown of your reactors. Unit 2 is nowhere near a cold shutdown and if TEPCo is wrong about most of its melted down core still being within the reactor housing, well, no one knows when a cold shutdown can be achieved. In fact, if independent scientists are right and the three melted down cores have melted through their containment vessels and are burrowing slowly into the ground, it is hard to imagine how recriticality can be avoided. Frankly, nobody has a clue as to where, exactly, the melted fuel might be. In such conditions, it is unlikely that long-term recriticality will be sustained, but it is also equally unlikely that–not knowing where to inject what –“flare ups” can be avoided. Since the “flare-ups” of recriticality we are talking about release lethal doses of radiation, this is again, to put it mildly, a problem.
All of this is continuing to produce a Hell’s Brew of toxic pollution from the plant with high levels of Iodine-131, Cesium-134 and Cesium-137 still being reported in the sea off Fukushima. Now an entirely new radioactive isotope, Krypton-85 (please, no Superman jokes) has been detected at Unit 2. So why do we care about Krypton-85? Krypton-85 is a marker of plutonium separation, i.e., some pretty major reactions are going on in what’s left of that reactor. Unit’s 1 and 3 may be going critical, as well. Frankly, it is pretty clear that TEPCo hasn’t a clue what the hell is going on in the melted reactor cores but the indications are not good. No kidding they’re injecting boric acid into the core–if the cores have sustained recriticality that could lead to all sorts of problems, including large releases of radiation and further hydrogen explosions. Fukushima, in other words, is not willing to give up its time in the limelight, not just yet.
If all this were not bad enough, Unit 2 may be sporting a new hole blown through reinforced concrete (h/t Joieu at DailyKos), which, to put it mildly again, would be bad. Very bad. The explosive forces that could rip a hole through that wall means we’re back in the bad ol’ days of March when radioactivity was spewed into the atmosphere in much greater quantities than previously reported (see above). This latest worry has not been confirmed or even much discussed outside of Japan, so it is best not to be alarmist (or rather, to cross one’s fingers and hope Fukushima is not up to its old tricks).
So, technically Fukushima is worse than Chernobyl’ (Ha! Take that you apologists from last spring!) but not really (Xenon is just not as bad as Cesium or Iodine). And yet, we may very well be witnessing the second act of Fukushima’s tragedy, an act that the poor, suffering folk in Japan would love to skip. I dearly hope Chernobyl’ keeps its number one spot in this particular rogues’ gallery but I’m very nervous about what could be happening in Unit 2.