Japan is facing power shortages this summer and difficult, long-term questions about how it will meet its energy needs in the wake of the Fukushima nuclear crisis.
Government officials want three reactors at the Hamaoka power plant, which is about 200 kilometres west of Tokyo, shut down until the plant's safety systems are improved.
Japan has been working to conserve energy since the March 11 earthquake and tsumani that crippled the Fukushima plant. Lights have been turned down or off, stores have trimmed service hours and subway operators have shut off the air conditioning.
The Hamaoka plant is a key power provider in central Japan, including nearby Aichi, home of Toyota Motor Corp.
The plant's operator, Chubu Electric Power Co., estimates the three reactors could put out at most about 30 million kilowatts this summer, narrowly meeting the estimated demand of 26 million kilowatts.
"It would be tight," said company official Mikio Inomata, adding that officials are discussing the possibility of boosting output from gas, oil and coal-fueled power plants and purchasing power from other utility companies.
Chubu Electric executives have not yet decided whether to shut down the reactors.
Prime Minister Naoto Kan said Friday that the closure request was for the "people's safety." He noted that experts estimate there is a 90 per cent chance that a quake with a magnitude of 8.0 or higher will strike the region within 30 years.
Residents of Shizuoka prefecture, where Hamaoka is located, have long demanded a shutdown of the plant's reactors. About 79,800 people live within a 10-kilometre radius of the complex.
Since the March 11 disasters, Chubu Electric has drawn up safety measures that include building a 12-meter-high seawall nearly a mile 1.5 kilometres long over the next two to three years, company officials said. Chubu also promised to install additional emergency backup generators and other equipment, and improve the water tightness of the reactor buildings.
The Hamaoka plant lacks a concrete sea barrier now. Sand hills between the ocean and the plant are about 10 to 15 metres high, deemed enough to defend against a tsunami around 8 metres high, officials said. The operator of the Fukushima nuclear plant, Tokyo Electric Power Co., has said the tsunami that wrecked critical power and cooling systems there was at least 14 metres high.
Nuclear energy provides more than one-third of Japan's electricity. Critics of nuclear power have been vocal since the disaster at Fukushima, but Deputy Chief Cabinet Secretary Yoshito Sengoku said the government has no plans to shut down any more functioning nuclear reactors other than three at the Hamaoka.
"Our energy policy is to stick to nuclear power," Sengoku said on a weekly talk show on public broadcaster NHK.
Sengoku said there is "no need to worry" about other plants in the country.
Scientifically, that's our conclusion at the moment," he said.
