The unit is Hokuriku Electric's second and has been undergoing a test run since last July. Its full start-up will bring Japan's nuclear-power generation capacity to 49.58 million kw.

Japan, which has the world's third-largest nuclear power generation capacity after the United States and France, has a policy of supporting nuclear power, due to its lack of natural resources such as oil and natural gas and a global move to cut greenhouse gas emissions.

Nuclear power plants now generate about 30 percent of the electricity used in Japan and the government plans to raise that to 40 percent by 2010 by installing new units.

However, the domestic nuclear power industry has been under increasing public criticism because of recent safety scandals and a fatal accident at a plant run by one of Hokuriku's peers.

In August 2004, hot water and steam leaking from a broken pipe at a nuclear plant run by Kansai Electric Power Co. in western Japan killed five workers, marking the country's worst-ever nuclear power accident.

The company had not inspected the pipe since the unit in which it was located started operating in December 1976.

That accident followed an admission by Tokyo Electric Power Co. that it had falsified nuclear safety documents for more than a decade, a revelation that forced it to shut all 17 of its nuclear power generators for inspections by mid-April 2002.