The reactor cores have been almost dry for many days. The fuel rods protrude meters high from the remaining cooling water. At least. And wasn’t it always said: if a core becomes dry, it completely melts in less than an hour? Nobody can see inside the reactors at the moment, even most of the measuring instruments have failed.
Despite the cooling of the reactors, no all-clear
A helicopter must have flown over the power plant at noon today and measured the temperature on the surface of the reactor vessels: less than 100 degrees, the Japanese defense minister cheered on television. The temperature is also falling in blocks 5 and 6, which were out of order at the time of the accident. That’s good news. Nevertheless, the Society for Plant and Reactor Safety says that the Fuel rods are “damaged”. One can imagine that parts of the material, the fuel rods, control rods and the container box are fused together. At around 1200 degrees, uranium becomes liquid. No matter how much that is, apparently none of it has melted down. And this, even though no so-called core catchers have apparently been installed in Fukushima, tanks that are supposed to prevent the melting material from getting into the groundwater
The attempts, which seem more or less helpless to cool the reactors from the outside, seem to have had some success. At this point in time, it looks like the situation could turn out like a larger version of the Three Mile Island case. In 1979 there was also a partial meltdown in this power plant in the USA, which could be stopped. (That was also a serious accident, see the previous blog entry from me.) Over time, the decay heat also decreases clearly. So there is hope that things don’t have to get worse. However, none of this reverses what has already happened. And that’s bad enough. And the radioactive material that has become free remains with us for a very long time. What is left there will be a problem for a very long time.
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Questions about Fukushima
The SWR environment editors Werner Eckert and Axel Weib answered numerous questions about Fukushima in the blog. this site has now combined these texts, which were originally written for the blog, into a dossier.