NISA to order fault surveys at Mihama plant, Monju reactor

August 25, 2012

THE ASAHI SHIMBUN

The Nuclear and Industrial Safety Agency plans to order geological fault surveys at two additional nuclear power facilities, which could lead to a decommissioning of both facilities.

The nuclear watchdog said Aug. 24 that surveys, including excavations, are necessary at Kansai Electric Power Co.’s Mihama nuclear plant and Japan Atomic Energy Agency’s Monju prototype fast breeder reactor, both in Fukui Prefecture.

The two companies have said that faults running directly below their reactor buildings are not active, but NISA concluded that more information is needed.

“We need to take into account earthquakes that are not normally expected,” said Shinji Toda, a NISA panel member and Kyoto University associate professor, referring to the March 2011 Great East Japan Earthquake. “Past documents provide only insufficient data.”

A nuclear reactor cannot be installed above an active fault under the government’s quake-resistance standards for nuclear power plants.

NISA had already ordered fault re-examinations at four nuclear power plants: Japan Atomic Power Co.’s Tsuruga plant; Hokuriku Electric Power Co.’s Shika plant; Kansai Electric Power Co.’s Oi plant; and Tohoku Electric Power Co.’s Higashidori plant.

NISA has inspected faults at 18 nuclear power facilities in Japan since its expert panel said in April that a fault running directly below a reactor building at the Tsuruga plant in Fukui Prefecture may be active.

The agency concluded that additional geological surveys are necessary at the six facilities, saying faults under the premises may be active.

Experts say a fault running directly below a reactor building at the Shika plant in Ishikawa Prefecture may be active.

Kansai Electric and Tohoku Electric have said faults at the Oi plant in Fukui Prefecture and the Higashidori plant in Aomori Prefecture are not active, but NISA ordered follow-up surveys.

NISA said further fault studies are necessary for three nuclear power plants--Tokyo Electric Power Co.’s Kashiwazaki-Kariwa plant, Chubu Electric Power Co.’s Hamaoka plant and Kansai Electric’s Takahama plant--but said additional geological surveys are not required at present.

TEPCO, operator of the stricken Fukushima No. 1 nuclear power plant, plans to conduct a voluntary geological survey at the Kashiwazaki-Kariwa plant in Niigata Prefecture in an attempt to reactivate it at an early date.

NISA said no problems have been found at the remaining nine nuclear facilities.

THE ASAHI SHIMBUN
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The Mihama nuclear power plant in Fukui Prefecture (Asahi Shimbun file photo)

The Mihama nuclear power plant in Fukui Prefecture (Asahi Shimbun file photo)

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  • The Mihama nuclear power plant in Fukui Prefecture (Asahi Shimbun file photo)

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