TOKYO - Japan on Monday announced a tiny radiation leak at a nuclear reactor on its west coast, while another power company is expected to close a nuclear plant in central Japan due to its vulnerability to a major quake.

Electricity wholesaler Japan Atomic Power said it had stopped the leak after a minute amount of radiation was found in gas that escaped from the Tsuruga nuclear plant on Sunday. It said there had been no impact on the environment.

Japan Atomic Power said it was investigating the cause of the leak, which is bound to increase public unease over the troubled nuclear industry in the wake of the massive earthquake and tsunami that crippled the Fukushima nuclear facility in March.