Reactor No. 2 heats up, gets more water Kyodo

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Workers at the Fukushima No. 1 nuclear plant increased the amount of water injected into reactor 2 on Tuesday to the highest level since the plant achieved cold shutdown in December as concerns grew over rising temperatures at the bottom of the pressure vessel.

Following the move, the temperature at the bottom of the vessel eased to 69.0 degrees by 10 a.m. from 72.2 logged at 5 a.m., said Junichi Matsumoto, spokesman for Tokyo Electric Power Co., adding that Tepco needed more time to assess the effectiveness of the step.

"It is difficult to judge whether the temperature is rising or dropping unless we monitor the development for about a day," Matsumoto said.

Tepco said it increased the amount of injected water, some of which contained boric acid, at 4:24 a.m. Tuesday. Reactor 2 is now being cooled with 13.5 tons of water per hour, up from 10.5 tons. The boric acid is being used to prevent a sustained nuclear chain reaction, or recriticality.