Japan plans no more air drops of water on stricken nuclear reactor

YAMAGATA, Japan -- Japan's military says it does not plan further helicopter air drops of water on overheating reactors at a tsunami-ravaged nuclear plant.

Defense ministry spokesman Ippo Mayama said Friday local time that further helicopter runs were not planned, following several runs the day before. He did not say why. It was unclear what effect the water drops had on the targeted reactor.

While the choppers flew combat-style missions to dump batch after batch of seawater onto a stricken reactor, plant operators said they were close to finishing a new power line that could restore cooling systems and ease the crisis at the Fukushima Dai-ichi complex on the country's northeast coast.

The top U.S. nuclear regulatory official gave a far bleaker assessment of the crisis than the Japanese, and the U.S. ambassador warned U.S. citizens within 50 miles of the complex to leave the area or at least remain indoors.

The Japanese government said it had no plans to expand its mandatory, 12-mile exclusion zone around the plant, while also urging people within 20 miles to stay inside.

The troubles at the nuclear complex were set in motion when last week's magnitude-9.0 earthquake and tsunami knocked out power and destroyed backup generators needed for the reactors' cooling systems. That added a nuclear crisis on top of twin natural disasters that likely killed well more than 10,000 people and left hundreds of thousands homeless.

Four of the plant's six reactors have faced serious crises involving fires, explosions, damage to the structures housing reactor cores, partial meltdowns or rising temperatures in the pools used to store spent nuclear fuel. Officials also recently announced that temperatures are rising in the spent fuel pools of the last two reactors.

Japan's top government spokesman said Tokyo is willing to accept U.S. help in dealing with the country's nuclear crisis, and is discussing the matter with Washington.

"We are coordinating with the U.S. government as to what the U.S. can provide and what people really need," Yukio Edano said. "We have repeatedly asked for specific support, and indeed, they are responding to that."

Meanwhile, the International Atomic Energy Agency chief, Yukiya Amano, said he views Japan's nuclear crisis as an extremely serious accident requiring international cooperation.

Amano said he plans to meet with top Japanese officials and to visit the area struck by the earthquake and tsunami a week ago that knocked out power for the cooling systems at a nuclear power plant, setting off Japan's crisis.

Amano will be accompanied by a four-member team of experts.

"We see it as an extremely serious accident," he said. "The international community is extremely concerned about this issue, and it's important to cooperate in dealing with it."