There was some evidence of uncontrolled nuclear fission at the wrecked nuclear power plant in Japan's Danger Zone
Operator of nuclear power plant "Fukushima-1" said the November 2, 2011 in the reactor showed signs of nuclear fission, which could be the result of cold shutdown of the reactor. Xenon isotopes that are released when the reaction of nuclear fission, were found recently in a second reactor.
Kazushiko Kudo proposed two assumptions under which it could be nuclear fission. On the first accident occurred during the melting of nuclear fuel, which also caused the reaction. Or small radioactive elements formed in the accident, could lead to a clash of neutrons and fission of uranium, thus causing a small nuclear fission reaction.
At the moment to cool three damaged reactor continuously pumped water, so the temperature in their stable.