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HOME  > Past issues  > 2012 November 7 - 13  > Possible active fault under Oi NPP requires more research: NRA
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2012 November 7 - 13 [NUCLEAR CRISIS]

Possible active fault under Oi NPP requires more research: NRA

November 8, 2012
An expert panel under the Nuclear Regulation Authority on November 7 urged Kansai Electric Power Company to conduct additional research on a fault fracture zone below the premises of the Oi nuclear power plant.

The fracture zone in question, a suspected active fault, was found near Units 2 and 3 of the plant. It runs directly underneath an emergency water intake channel which receives seawater to cool nuclear reactors in case the reactor’s cooling system is damaged.

If the fault is determined to be an active fault, the plant’s operations will be shut down under applicable laws.

KEPCO in July investigated the fault based on instructions from the former Nuclear and Industrial Safety Agency and submitted to the NRA an interim report on October 31. In the report, the company claimed that the fault is hardly recognized as active. Separately from KEPCO’s investigation, the NRA expert panel on November 2 visited the plant to carry out a geological survey.

The expert panel on November 4 held a meeting to consider whether the zone is an active fault or not in accordance with the result of the site exploration and the KEPCO’s report. The panel, however, could not reach a conclusion.

At the second meeting on November 7, the experts criticized KEPCO’s data and explanation associated with its report as insufficient and the panel decided to continue looking into the matter.

Stating, “Because the utility didn’t conduct scientifically verifiable surveys in the past, the current situation occurred,” NRA deputy chair Shimazaki Kunihiko requested the Oi operator to conduct a reinvestigation at a spot nearby the previous investigation spot.

Toyo University professor Watanabe Mitsuhisa, who has asserted the possibility of an active fault for a long time, pointed out that no experts in the panel denied the possibility that the fracture zone is an active fault. He called for an immediate shutdown of Units 3 and 4, the first reactivated reactors after the Fukushima accident.
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