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information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise

Fault under Tsuruga IS active

November 20, 2014

Nuclear watchdog panel: Fault under Tsuruga reactor is active



A fault line beneath the No. 2 reactor of the Tsuruga nuclear power plant is indeed active, an expert panel of the Nuclear Regulation Authority concluded Nov. 19, drawing criticism from the plant’s operator.

Japan Atomic Power Co. vowed to challenge the panel’s conclusion, which, if it stands, would force the company to decommission the reactor under new safety rules.

“It is a rash, one-sided judgment and just a presumption,” Japan Atomic Power Vice President Taiki Ichimura told reporters after the Nov. 19 meeting of the NRA panel. “We are confident that we will be able to rebut and disprove the conclusion.”

The NRA in May 2013 pointed out the possibility that the fault line beneath the No. 2 reactor building of the Tsuruga plant in Fukui Prefecture could move in conjunction with the nearby Urasoko active fault.

Japan Atomic Power, citing its own survey results, said the fault under the reactor was not connected to the Urasoko fault’s branch and was not active.

After reassessing the conditions at the Tsuruga plant, the expert panel said in its draft report Nov. 19 that the fault under the reactor building “could move in the future,” repeating the NRA’s stance last year.

The NRA is expected to finalize the draft after it is examined by other experts.

Under stricter safety standards introduced after the Fukushima nuclear crisis triggered by the March 2011 Great East Japan Earthquake and tsunami, reactor buildings cannot be built directly above active faults. Japan Atomic Power will likely be unable to restart the No. 2 reactor unless the panel’s draft report is dismissed.

The NRA’s assessment of the fault last year came when Kunihiko Shimazaki, a seismologist known for his tough attitude toward power companies, was a deputy chairman of the watchdog. Utilities and ruling coalition officials criticized Shimazaki over his “hurried conclusion” on the Tsuruga plant.

Although Shimazaki’s term ended in September and he was replaced, the NRA’s position on the fault was not overturned.

The fault line survey at the Tsuruga plant was originally started at the request of the now-dissolved Nuclear and Industrial Safety Agency.

Fault inspections are a separate process from the safety screenings required to restart reactors, so Japan Atomic Power can still submit an application to resume operations at the reactor.

However, NRA Chairman Shunichi Tanaka has said he would respect the expert panel’s conclusion when deciding whether to allow reactors to restart.

(This article was written by Chikako Kawahara and Daiki Koga.)

Experts retain Tsuruga reactor fault judgment in draft report


TOKYO (Kyodo) -- A panel of experts under Japan's nuclear regulator on Wednesday reaffirmed an earlier judgment that a reactor at the Tsuruga nuclear station is sitting right above an active fault, a move that could force the operator to permanently shut down the unit.

After the Nuclear Regulation Authority acknowledged last year that the fault in question is active, Japan Atomic Power Co. has submitted additional data in trying to have it overturned.

The experts, however, concluded that the new data offered no evidence to sway the judgment as it compiled a new draft report on the fault's assessment.

A zone of rock fragments called D-1, running directly beneath the No. 2 reactor at the plant, is a "fault that could move in the future," the draft report said.

Under the country's nuclear safety requirements, plant operators are not permitted to build reactors and other important safety facilities directly above active faults -- currently defined as those that have moved in the last 120,000 to 130,000 years.

The draft report will likely be finalized by an NRA decision-making panel after making amendments to details -- which will make it difficult for Japan Atomic Power to resume the unit's operation.

All of Japan's nuclear reactors are currently offline. To go back online, they must pass the regulator's safety screening process based on tougher regulations adopted in the wake of the 2011 Fukushima nuclear crisis.

Japan Atomic Power Vice President Taiki Ichimura said he believes the assessment is not based on specific evidence and it is a "one-sided assumption."

"I'm sure we can counter the judgment," he told reporters after the panel meeting, adding he will ask the NRA to create an occasion for more discussion.

If the company has to decommission the unit, its business would be negatively affected by scrapping costs and a loss in asset value.

See also :

Fault beneath Tsuruga nuclear reactor is active, watchdog panel reaffirms



A reactor at the Tsuruga nuclear station is sitting right above an active fault, a panel of experts under Japan’s nuclear regulator has reaffirmed — a move that could force the operator to shut the unit for good. […]

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