Four Japanese electricity workers were killed and seven injured when turbine steam escaped at a nuclear plant in Mihama, on the Sea of Japan. The incident, involving the highest number of fatalities at a Japanese nuclear power plant, has heightened concern about the nuclear industry.

The Kansai Electric Power Company that operates the Mihama plant stopped power generation. The actual cause of the accident is yet to be ascertained though local media have quoted an official as saying that a lack of cooling water caused the accident. An ultrasound scanning might have detected the weakness in the pipes, but no such tests had ever been carried out in the 28-year-old facility.

According to an official from Japan's Nuclear and Industrial Safety Agency, it would be impossible for the leaked steam to contain radioactivity, as the turbines did not come into contact with water used in the nuclear reactor. Nobutake Masaki, a Mihama city official, said no radiation leaked from the plant, and that the steam had leaked only inside the building. Two hundred people were inside the building when the mishap occured.

Japan has more than 50 nuclear plants, providing 34 per cent of its energy needs, but the industry has been dogged by a series of accidents and attempted cover-ups.