A Japanese utility operator has denied any problematic nuclear reactions at a tsunami-hit power plant, saying a radioactive gas in one of the damaged reactors came from spontaneous fission that occurs in any idle reactor.
The operator this week found radioactive xenon, initially hinting unexpected nuclear fission and injected boric acid as a precaution against further nuclear reactions.
The Tokyo Electric Power Co said further examination determined that xenon was produced by curium, a nuclear fuel component that causes spontaneous fission.
The utility denied any new problem inside the Unit 2 reactor, citing no change in temperature or pressure.
It said a recently installed more sensitive monitor detected xenon that was there all along.