Deputy Chief Cabinet Secretary Yoshito Sengoku also said no reactors other than the three units at the Hamaoka power plant in central Japan would be shuttered over quake and tsunami concerns.

There is "no need to worry" about other reactors, Sengoku said. "Scientifically, that's our conclusion at the moment."

The government evaluated Japan's 54 reactors for quake and tsunami vulnerability after the March 11 disasters that heavily damaged the Fukushima Dai-ichi plant in northeast Japan.

Chubu Electric Power Co., which runs the Hamaoka plant, is still considering the government's request to shut the reactors while the utility builds a seawall and improves backup systems to protect the reactors from a major earthquake and tsunami.

Nuclear energy provides more than one-third of Japan's electricity, and shutting the three reactors would likely worsen power shortages expected this summer. Already, buildings have reduced lighting, stores have trimmed service hours and subway operators have shut air conditioning in a conservation effort in the capital region since the March 11 disasters.

After an executives' meeting Saturday failed to finalize a decision, Chubu chairman Toshio Mita left for Qatar to negotiate for liquefied natural gas supplies to cover the shortfall, company official Tatsuo Sawaki said sunday.