Four killed at accident in Japan nuclear plant

A steam leak at a nuclear power plant northwest of Tokyo has killed four workers and injured at least 10 others, several critically, Japanese media and officials have reported.

Kyodo News Service and public broadcaster NHK reported that four workers had died after suffering severe burns, and that at least one other worker was in critical condition.

Those who died were exposed to steam as hot as 200 Celsius (392 Fahrenheit), officials said. The accident was described as the worst ever in terms of deaths at a nuclear facility in Japan.

Eleven people were injured in the accident, with five suffering from heart and lung failure, Japan's nuclear agency said.

Japanese officials said the leak from one of the reactors at the Mihama Nuclear Power Plant in Fukui Prefecture was not radioactive, Kyodo news agency reported.

Energy officials said no danger was posed to the surrounding area and no evacuation order was issued for the plant, which lies 320 kilometers (200 miles) northwest of Tokyo.

The accident struck at around 3:30 p.m. (0630 GMT) just after some workers had entered the facility to take measurements ahead of a scheduled shutdown for maintenance, NHK reported.

The 826,000-kilowatt pressurized-water reactor, which began service in 1976, was automatically shut down after the accident.

Japan depends on nuclear power for about one-third of its electricity. The Mihama plant was the first nuclear plant built by Kansai Electric Power Co. Inc.

"We are now investigating the cause," a Kansai Electric official told a news conference.

The accident was the worst since 1999, when a radiation leak at a fuel-reprocessing plant in Tokaimura killed two workers and affected hundreds of others, according to The Associated Press.

That accident was caused by two workers who tried to save time by mixing excessive amounts of uranium in buckets instead of using special mechanized tanks.

A string of safety problems since has undermined public faith in nuclear energy and left Japan's program in limbo.