The operator of Japan's Hamaoka Nuclear Power Plant agreed to temporarily shut down three reactors today, amid rising concerns about their ability to withstand a powerful earthquake and tsunami.
The decision came days after Prime Minister Naoto Kan urged Chubu Electric, Japan's third-largest power producer, to halt the plant's operations, citing a government study that forecast a magnitude 8.0 quake hitting the Hamaoka area in the next 30 years.
The aging plant located in Shizuoka, 125 miles southwest of Tokyo, sits on a major fault line where nearly 80,000 people live within a six-mile radius.
Safety activists have long questioned Hamaoka's ability to protect its reactors from large waves, but those concerns have grown louder since a magnitude 9.0 earthquake and a tsunami devastated the northeast coast, crippling reactors at the Fukushima Daiichi nuclear plant.
The utility currently relies on sand dunes to block waves, and has said it would take a few years to build a seawall.
"We understand that the prime minister's request is based on increased concerns over nuclear power in the wake of the Fukushima Dai-ichi nuclear power plant accident," said Chubu Electric president Akihisa Mizuno at a news conference. "We believe that our efforts to strengthen safety will restore trust among people in the region and society."
Chubu Electric will halt two reactors at the plant, while a third, already shut down for regular maintenance, will remain offline indefinitely. Two older reactors were decommissioned in 2009.
Nuclear energy provides more than one-third of Japan's electricity, with Hamaoka's three reactors accounting for more than 10 percent of Chubu's power supply. Shutting down the plant is likely to further strain the country's energy supply, already hurting from the nuclear disaster at the Fukushima plant.
Hamaoka supplies power to about 16 million people in regions that include Aichi, home to Toyota and Honda car companies.
Some nuclear experts lauded the decision to halt the reactors in central Japan, but questioned the timing.
"The decision to shut down the reactors should have been purely a scientific decision, but the prime minister's made it a political one," said Shigeharu Aoyama, a special consultant to the Japan Atomic Energy Commission.
Kan has faced increasing criticism for his handling of the March 11 disasters, which triggered hydrogen explosions and radiation leaks in the world's second-worst nuclear crises. Critics have accused the government of acting too slowly in the early hours of the crises, making the situation worse.
The disaster prompted the government to call for safety inspections at all of Japan's 54 nuclear plants. But officials insist there are no plans to halt other nuclear reactors, saying there is "no need to worry" about the other plants.
"Our energy policy is to stick to nuclear power," Deputy Chief Cabinet Secretary Yoshito Sengoku said on a weekly talk show Sunday. "Scientifically, that's our conclusion at the moment."
Aoyama called the government's statement premature. "The government hasn't even updated their safety standard since March 11," he said. "It's too early to say they won't close other plants, without a proper safety plan in place."
Chubu stocks fell more than 10 percent today on anticipation of the utility's move, and Mizuno said he was bracing for more financial fallout from his decision. Minister of Economy, Trade and Industry Banri Kaieda said the government would provide financial support to Chubu to cover related costs and losses.