A steam leak at a Japanese nuclear power plant on Monday killed four people and injured seven. The leak, fortunately, was not radioactive.

The leak occurred at the nuclear power plant in Mihama city, around 300 kilometres from capital Tokyo.

One of the injured workers is reportedly critical. The four died after suffering severe burns.

The accident was caused by a lack of cooling water in the turbine, said Kimihito Kawabata, a spokesman for the Kansai Electric Power. The steam was believed to be about 270 C.

Takahiro Seno, a spokesman for plant operator Kansai Electric Power, said the plant automatically shut down when steam began spewing from a leak in the turbine building area at the No 3 nuclear reactor in Mihama.