This is a particularly important update. An anonymous source in Japan has told reporters connected to the New York Times that there is a visible crack in the Fukushima Reactor 3. This is the reactor that showed isotopic evidence of a leak of some kind. Arguments had been made that a hole in the reactor vessel was an impossibility. The increasingly convincing evidence of a leak led people to admit, or realize, that the reactor vessel already has holes in it … those designed to allow pipes and such in and out of the large thick-walled metal object. It was then presumed that this is where leakage was happening, and that remains a distinct possibility. This presumption was based on the repeatedly stated impossibility of the reactor vessel being burned or corroded through.
But now we have evidence of a visible crack. A crack is a whole nuther matter. If there truly is a crack and the crack is through-and-through and allowing leakage, the we may be observing an excellent and disturbing example of how nuclear accidents often play out, and, in fact, why they happen to begin with. There have been repeated arguments made, in the press, on this blog (in comments), and elsewhere that there is no way that even melted down nuclear stuff inside the reactor vessel could eat its way through that vessel. Then a concession was made for pipe-holes. In the end, however, eating through the vessel or corroded or melted pipes may not be the point. Cracking the vessel then leaking out may be a possibility. Hadn’t been considered before.
There is isotopic evidence that the material leaking out of Reactor 3 is in part the product of fission that has occurred since shutdown of the machine at the time of the earthquake. This is not confirmed and there may be other explanations. But, if that is true, this probably means that fuel pellets have come free of their containment in fuel rods and accumulated somewhere in the reactor vessel in sufficient density to cause a chain reaction. If this has happened, it is probably not that severe of a chain reaction (or we would see more heat and other bad things). But, if there are fuel rods that have fallen apart, this means that future movement or pressure changes or other effects in the vessel could be more dangerous. Under some scenarios, just adding water can cause a brittle corroded fuel rod to fall apart, dropping more pellets into an accumulating pile of pellets lower down in the vessel.
Put metaphorically, the concentration of radioactive material in a mass that is increasingly close to that necessary to cause a chain reaction was dubbed, in the early days of nuclear research, “tickling the dragon’s tail.” Researchers, it is said, would move two piles of radioactive stuff closer and closer and measure the increase in radioactive output, in part to determine what a “critical mass” would be for that material. In theory, they would stop just before a high-level reaction occurred. Louis Slotin went to far with this technique in May, 1946 and it killed him.
If the isotopic evidence truly indicates that there has been post-quake fission in the reactor chamber, then this may mean that there is a dragon in there, metaphorically speaking We just have to hope that the Japanese engineers know how to keep the dragon calm.
There are other startling developments including a shakeup in the government. Ana has put together a very interesting feed. Read on:
Continue reading Japan quake, tsunami, nuke news 10 … Tickling the Dragon’s Tail?