Four workers came into contact with radioactive coolant water in a Japanese nuclear power plant, but the operator said today that there had been no effect on their health or on the environment from the leak.

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The incident in Kansai Electric Power Co.'s Takahama plant in the western prefecture of Fukui occurred yesterday afternoon during a regular inspection while the unit was shut, the company said.

Just last week, Kansai Electric restarted the No. 3 nuclear power generation unit in its Mihama plant for commercial operations after a shutdown following Japan's worst-ever nuclear power plant accident more than two years ago.

In the August 2004 accident, hot water and steam leaking from a broken pipe in the plant killed five workers.