The operator of tsunami-hit nuclear power plant in Japan said on Wednesday it had found substances in a reactor which could be a result of nuclear fission, a possible setback in efforts to bring the plant to a safe, cold shutdown. Analysts said there was unlikely to be any heightened risk of radiation. The Fukushima Daiichi plant was struck by a devastating earthquake and tsunami in March and has released radiation into the atmosphere ever since in the world’s worst nuclear crisis since Chernobyl 25 years ago. Tokyo Electric Power said that it discovered xenon, a substance produced as a byproduct of fission, in the No 2 reactor, and had poured in a mixture of water and boric acid, an agent that helps prevent nuclear reactions, as a precaution.
“It can be assumed that isolated criticality took place for a short period of time judging from the presence of xenon,” Tepco spokesman Junichi Matsumoto told reporters. Criticality is a state when controlled nuclear reactions take place. Nuclear power plants harness the resulting heat to produce electricity. Richard Wakeford at the University of Manchester said his initial response to the Tepco findings was “scepticism”. “Nuclear criticality requires delicate conditions,” Wakeford said in an email. “And it seems unlikely that these exist at Fukushima… Also, criticality would be accompanied by a burst of radiation, which I would have expected to be detected.”
