Nuclear watchdog to forbid reactor construction above active faults

January 23, 2013

By RYUTA KOIKE/ Staff Writer

To clarify a loosely defined government "guideline," the nuclear industry watchdog decided on Jan. 22 it will expressly prohibit reactor buildings and other key safety-related facilities from being built directly above active fault lines.

The decision came during a meeting of an expert panel of the Nuclear Regulation Authority on new safety standards on nuclear plants’ preparedness against earthquakes and tsunami.

The restriction could make it more difficult for the ruling Liberal Democratic Party to consider proceeding with construction of new nuclear power plants, if the sites are assessed to be over active faults. Under the previous Democratic Party of Japan, approval for the construction of new reactors had been frozen following the accident at the Fukushima No. 1 nuclear power plant in March 2011.

In its current anti-seismic guidelines, the government already has a similar provision prohibiting construction of nuclear reactors above active fault lines. But the NRA is seeking to make that provision clearer and more binding by upgrading the prohibition from “guidelines” to “standards.”

The current entry in the anti-seismic guidelines only indirectly bans key equipment from being installed directly above an active fault that cuts across the ground surface, saying such construction is already “not assumed” to be taking place. The new safety standards will use more direct wording and expressly state that nuclear reactor buildings and other key safety facilities should be built on sites confirmed to be free of active faults.

The NRA plans to draw up an outline of the new standards by the end of January, and put them in place by July.

The NRA has already said it plans to expand, in the new standards, the definition of an active fault from “one that shifted during the past 120,000 to 130,000 years” to “one that moved during the last 400,000 years.”

It also said it will define maximum anticipated heights of possible tsunami and obligate nuclear plant operators that are vulnerable to prepare defenses against them.

By RYUTA KOIKE/ Staff Writer
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An active fault line likely runs beneath the No. 2 reactor of the Tsuruga nuclear power plant in Fukui Prefecture. (Asahi Shimbun file photo)

An active fault line likely runs beneath the No. 2 reactor of the Tsuruga nuclear power plant in Fukui Prefecture. (Asahi Shimbun file photo)

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  • An active fault line likely runs beneath the No. 2 reactor of the Tsuruga nuclear power plant in Fukui Prefecture. (Asahi Shimbun file photo)

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