The Osaka District Court on Tuesday rejected local residents' calls to halt an aging nuclear reactor at Kansai Electric Power's Mihama power plant in central Japan that started operations more than 40 years ago.

The court ruling marked the first judicial decision over the safety of an aging reactor. It was handed down after local residents sought suspension of the No. 3 unit of the plant in Fukui Prefecture due to safety concerns.

The decision came as the government seeks to extend the maximum service period for the country's existing nuclear reactors beyond 60 years. The reactor is the only one that operates in Japan beyond the country's 40-year service period in principle.