Chubu Electric Power Co. will begin shutting reactors at its Hamaoka nuclear plant tomorrow, after the government asked Japan’s third-largest utility to idle them until earthquake and tsunami defenses are improved.
The Nagoya-based company will start the process of closing the 1,137-megawatt No. 4 unit at Hamaoka around 3 p.m. local time tomorrow, Atsuo Sawaki, spokesman at the utility, said by telephone today. The 1,380-megawatt No. 5 reactor will be shut the following day, he said.
Chubu Electric this week agreed to Prime Minister Naoto Kan’s call to close the station 190 kilometers (118 miles) southwest of Tokyo for as long as three years to take protective measures such as building a sea wall. The move comes after an earthquake and tsunami knocked out backup power and cooling systems at Tokyo Electric Power Co.’s Fukushima Dai-Ichi station, causing the worst nuclear disaster in 25 years.
“If Hamaoka plant is hit by an earthquake and tsunami, idling the reactors won’t make a big difference to the extent of damage that may be caused,” said Kazuhiko Kudo, a research professor of nuclear engineering at Kyushu University. “The most important thing is to take measures to prevent station blackout and keep cooling systems working.”
Of the four reactors damaged at Fukushima, the No. 4 unit was shut for maintenance when the March 11 tsunami triggered by a magnitude-9 temblor cut backup power supply running the cooling system for its spent-fuel pond. The accident raised concerns about the safety of other nuclear plants in Japan.
Hamaoka, Chubu Electric’s only nuclear plant, has five reactors. Two of them are being decommissioned and one has been idled for maintenance since November.
The utility is yet to decide whether to remove the fuel rods from the reactors, said Akio Miyazaki, a spokesman for Chubu Electric.
“When we shut reactors for scheduled inspections, which normally take three to five months, we often take out the rods and move them to the spent-fuel pools, depending on the type of work,” Miyazaki said by telephone today. “It’s possible we may move them to spent-fuel pools during the shutdown period.”
Chubu Electric delayed the shutdown work from today because negotiations with Tokyo Electric and Kyushu Electric Power Co. on power-supply agreements had taken longer than expected, Kyodo News reported.
The company is completing arrangements to avoid power shortfalls at the two other utilities, Kyodo said, citing Akihisa Mizuno, president of Chubu Electric.
Mizuno met Trade Minister Banri Kaieda yesterday and received assurances that Chubu Electric would be able to resume power generation at Hamaoka once the safety measures are implemented, Kyodo said. He also sought government support for Chubu Electric, according to Kyodo.
The utility estimates the additional safety measures including the building of the sea barrier will cost about 30 billion yen ($370 million). The station lies close to an active fault line, and the government has estimated there is an 87 percent chance of an 8-magnitude earthquake in the area near the plant within the next 30 years.
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