Power for the cooling system for a storage pool for fuel was restored after a two-hour break at reactor No. 3, and there was no immediate danger from the breakdown, according to Tokyo Electric Power Co., the utility that operates Fukushima Dai-ichi in northeastern Japan.
Work to put up nets to keep out rats and other animals at Fukushima Dai-ichi plant in northeastern Japan inadvertently caused the power outage, TEPCO spokesman Akitsuka Kobayashi said. Details were not clear, and the outage was still under investigation.
A dead rat found near a switchboard was suspected of the power outage last month that led to a cooling system not working for two days at the plant.
Nuclear Regulation Authority spokesman Takahiro Sakuma said an alarm went off in the afternoon about the latest problem at reactor No. 3.
The cooling system can be turned off for two weeks before temperatures approach dangerous levels at the spent fuel storage pools. But if the water runs dry, the fuel rods, even spent ones, will spew enormous levels of radiation.
The plant went into multiple meltdowns after the March 2011 tsunami damaged backup generators and all cooling systems failed, including those for the reactors.
The plant is being decommissioned, but continues to have glitches.
Fears are growing about the safety of nuclear plants, and people have periodically staged streets protests that are rare in Japan.
Only two of the nation's 50 working power plants are up, and the government is running beefed up safety checks on the plants, including scrutinizing quake faults right below or near the plants.
Shinzo Abe, who became prime minister about three months ago, has expressed a desire to restart nuclear plants. Japan lacks natural resources and relied on nuclear energy for about a third of its electricity needs prior to March 2011. Energy imports have soared over the last two years, putting a strain on the economy.
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