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TOKYO-- Cooling systems have been restored for four fuel storage pools at Japan's tsunami-damaged nuclear plant, more than a day after a power outage halted the supply of fresh cooling water and raised concerns about the facility, which still relies on makeshift equipment.

Tokyo Electric Power Co. says the cooling system at the last pool at the Fukushima Dai-ichi plant was repaired early Wednesday.

It says pool temperatures were well within safe levels and the reactors were unaffected.

The utility says workers are still trying to determine the cause of the outage, which began when a brief power failure hit the plant Tuesday evening. A massive earthquake and tsunami two years ago caused extensive damage to the plant.