But this time, the Tokyo Electric Power Company, or Tepco, the utility that operates three nuclear plants, restored the cooling pump at the Fukushima Daini plant in about an hour and a half. The Daini plant is about seven miles south of Fukushima Daiichi, the ruined plant where three reactors melted down five years ago after tsunami waves inundated the power station and knocked out backup generators.
Tepco reported that it never lost power at either the Daini plant or its neighbor to the north after the Tuesday quake, which had a magnitude of 7.4, according to the Japanese weather service. “We took the regular actions that we should take when handling troubles,” Yuichi Okamura, acting general manager of the nuclear power division at Tepco, said at a news conference on Tuesday.
The company was prepared for big tsunamis, having built sea walls rising to about 46 feet at the Fukushima plants and enclosing backup generators in waterproof facilities, Mr. Okamura said.