Fault risk for Aomori nuclear plant is raised

Earthquake faults beneath the Higashidori nuclear power plant in Aomori Prefecture could be active and dangerous, a regulator said Friday.

Nuclear Regulation Authority Commissioner Kunihiko Shimazaki made this revelation at a press conference after a two-day on-the-spot survey of the plant, which currently has one Tohoku Electric Power Co. reactor but, according to plans, will have another one built for the utility as well as two constructed for and run by Tokyo Electric Power Co.

Shimazaki and other survey participants will meet Thursday to consider the results of their probe.

If the regulators suspect the faults are active, it may be difficult for Tohoku Electric to restart the now-offline reactor amid safety concerns stemming from the triple-meltdown disaster at Tepco's Fukushima No. 1 power plant.

The experts Thursday confirmed four crush zones, including those running near the reactor 1 building. They continued the survey Friday to determine when the zones moved and find out whether there is any possibility they will move again.

Tohoku Electric has offered the explanation that fault slips under the plant site are caused by changes in groundwater levels.

But Shimazaki said Thursday he can't accept that explanation.

Survey team member Yota Kumaki, a professor at Senshu University, said the same day Tohoku Electric's claim raises many questions.

Another team member, Hiroshi Sato, a professor at the University of Tokyo, said he can't understand on what grounds the company drew such a conclusion.

Tohoku Electric maintains there are no active faults beneath the plant and thus there are no safety concerns.

The plant is the third nuclear power station to be inspected by the NRA for possible active faults, following Kansai Electric Power Co.'s Oi plant and Japan Atomic Power Co.'s Tsuruga plant, both in Fukui Prefecture. None of the earlier probes has reached a conclusion.

Following the latest survey, the agency plans to conduct on-site fault studies at Hokuriku Electric Power Co.'s Shika plant in Ishikawa Prefecture, Kepco's Mihama plant and the Japan Atomic Energy Agency's Monju fast-breeder reactor, both in Fukui.

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