Nuclear fission signs seen at Fukushima

TOKYO, Nov. 2 (UPI) -- Signs of likely new nuclear fission were noticed at Japan's quake-crippled nuclear plant but there's no threat of any critical situation, its operator said.

The detection of a small amount of radioactive xenon gas was made by the Tokyo Electric Power Co. in the No. 2 reactor of the Fukushima-Daiichi plant in the Fukushima prefecture, which was struck by the March 11 earthquake and tsunami. The catastrophe set off Japan's worst nuclear plant crisis which is yet to be fully contained.

Early Wednesday, workers at the plant injected water containing boric acid to prevent any likely nuclear reaction at the reactor, Kyodo News reported. The company said the reactor's temperature and pressure remain stable.

The nuclear fuel in the reactor is believed to have melted after the quake knocked out its cooling system.

The report quoted a company spokesman as saying there was not sufficient energy generated by the fission to reach criticality, leading to a fission chain reaction and an increase in the reactor temperature.

The company has planned to bring about a cold shut down of the plant's damaged reactors by year-end. A company spokesman said the latest incident is not expected to affect that timetable.