TOKYO (Kyodo) — Tokyo Electric Power Co. said Wednesday that it has detected signs of a recent nuclear fission in the No. 2 reactor at the crippled Fukushima Daiichi power plant, but ruled out the possibility that a major criticality accident had occurred.
The plant operator injected early Wednesday water containing boric acid to control a possible nuclear reaction at the reactor, where nuclear fuel is believed to have melted when the cooling system failed following the devastating March 11 earthquake and tsunami. The company said the reactor’s temperature and pressure were stable.
As for the possibility of criticality, in which nuclear fuel sustains a fission chain reaction, the utility’s spokesman said such a phenomenon may have happened “temporarily or partially,” but he does not think enough energy has been generated to raise the reactor’s temperature and pressure.
The latest incident suggests that the plant’s seemingly stable situation could be fragile, even almost eight months after the crisis erupted. The world’s worst nuclear crisis in 25 years resulted in the meltdown of nuclear fuel in the Nos. 1 to 3 reactors at the Fukushima complex.
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