Four workers are dead and seven others injured in an accident at a nuclear power plant in western Japan. Officials are calling it the country's worst accident at a working nuclear reactor.
Firefighters say steam gushed out of a hole in a pipe, and filled one of the turbine facilities at the Number Three reactor of the Mihama Nuclear Power Plant. Rescue workers say those who died were exposed to steam that was about 200 degrees Celsius.
Officials at Kansai Electric Power say the reactor, fueled by enriched uranium, automatically shut down, and no radiation leaks were detected outside the facility. It is located in Wakasa Bay, next to a national park, 320 kilometers west of Tokyo.
Experts say the steam that leaked from the plant was vapor coolant and thus not radioactive.
Hiroshi Matsuura of Kansai Electric Power says the workers were apparently taking readings to prepare for an inspection scheduled for Saturday. Mr. Matsuura says the company regrets the death of the workers and wants to find the cause as soon as possible.
Prime Minister Junichiro Koizumi told reporters several hours after the accident that it is important to make sure this does not happen again. Mr. Koizumi says he wants government investigators to find out exactly what happened and to implement safety measures.
Mitsubishi Corporation built the Mihama Number Three plant in 1976.
Japan's last nuclear accident was in 1999, when two workers were killed at the Tokaimura reprocessing facility after they violated procedures for purifying uranium and set off a chain reaction.
Monday's accident coincided with the 59th anniversary of the atomic bombing of Nagasaki.
Japan is at the forefront of international opposition to nuclear weapons, but the resource poor nation is a big proponent of nuclear power, which gives Japan about one-third of its electricity.
Public concern has increased in recent years, however, with revelations of cover-ups of safety violations and lax inspections of reactors.