Shika nuke plant to be probed for active fault

Hokuriku Electric Power Co. plans to dig a tunnel under the reactor 1 building at its Shika nuclear power plant to investigate a suspected active fault.

According to the plan, Hokuriku Electric will bore a vertical hole nearly 2 meters in diameter to a depth of 40 meters alongside the reactor building in Ishikawa Prefecture , then a horizontal 50-meter-long tunnel until just under the building.

The utility submitted the plan to the Nuclear Industry and Safety Agency Wednesday. If experts give their approval at a hearing Tuesday, the company will begin boring this autumn. A final report is expected around January.

After re-examining documents submitted at the time of the plant's construction, the industry ministry's agency noted the S-1 fault under the southwestern part of the reactor 1 building may have been active in the late Pleistocene Epoch, 120,000-130,000 years ago, or later.

Under guidelines for evaluating the seismic resistance of nuclear plant designs, the fault could be deemed active, so NISA ordered the utility to check it again.

The company will check the S-1 fault directly and conduct boring surveys at the nuclear plant's site. It will also examine faults around the plant site that could move with the S-1 fault.

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