Tsuruga Nuke Plant Reactor 2 May Have Been Sitting on Top of Active Fault All These Years

As the mayor of Tsuruga City was strongly promoting nuclear power generation in the county in China that has a nuclear power plant with 6 operating reactors and 4 under construction, the Nuclear and Industrial Safety Agency warned the operator of Tsuruga Nuclear Power Plant that Reactor 2 of the plant may be sitting on an active fault.

Even in Japan, the national guideline is not expecting a reactor to be built on top of an active fault.

Reactor 2 of Tsuruga Nuclear Power Plant is a pressurized water reactor made by Mitsubishi Heavy Industries. Reactor 1 is a light water reactor by GE. Tsuruga's Reactor 2 was considered to be one of the better made PWRs in Japan. Both reactors have been shut down for regular maintenance.

Construction of Reactor 2 started in 1982, and the reactor started operation in 1987.

Two more reactors are being built at Tsuruga Nuke Plant. The reactors will be Advanced Pressurized Water Reactors (APWR) by Mitsubishi Heavy Industries. If they proceed with the construction, that is.

From NHK News (4/25/2012):

敦賀原発“活断層”で再調査へ

"An active fault" at Tsuruga Nuclear Power Plant to be studied again

福井県にある敦賀原子力発電所の地下を走る亀裂が活断層の可能性があると専門家が指摘したことを受けて、日本原子力発電は改めて現地調査を行うなどして対応を検討することにしています。

An expert has pointed out the possibility that cracks that run under Tsuruga Nuclear Power Plant in Fukui Prefecture are active faults. The Japan Atomic Power Company (JAPC) is going to do the survey again and come up with the plan.

福井県敦賀市にある日本原子力発電の敦賀原発では、２４日、活断層の専門家や原子力安全・保安院の担当者らが敷地内の地層が露出している地点を調査し、地中にある「破砕帯」と呼ばれる亀裂の状態を調べました。

On April 24, an expert in active faults and officials from the Nuclear and Industrial Safety Agency (NISA) studied the area where the strata are exposed at JAPC's Tsuruga Nuclear Power Plant in Tsuruga City in Fukui Prefecture. They particularly looked at the crack called "fracture zone".

その結果、専門家は２号機から西に１５０メートルほど離れた地中を走る亀裂について、「活断層の可能性があり、敷地内を走る浦底断層という活断層と連動して、地震の揺れが想定より大きくなる可能性がある」と指摘しました。

As the result, the expert pointed out that the crack that runs underground at about 150 meters west of Reactor 2 "may be an active fault, and it may move together with the active fault called Urazoko Fault that runs through the compound, making the shaking from an earthquake bigger than anticipated".

また、２号機の真下を走る別の亀裂についても活断層の可能性があるかどうか調べる必要があるとして、保安院は日本原電に対し、再調査を行うよう指示しました。

There is another crack that runs right beneath Reactor 2. It needs to be studied to determine if it is also an active fault. NISA has instructed JAPC to do the survey again.

国の耐震設計の指針では活断層の真上に原発の重要な設備を設置することは想定されておらず、２号機の真下の亀裂が活断層であった場合、２号機は運転が再開できなくなる可能性が出てきます。

The guideline for seismic design by the national government does not expect having an important facility of a nuclear power plant right above an active fault. If the crack beneath Reactor 2 turns out to be an active fault, there is a possibility that JAPC cannot restart the reactor.

これを受けて、日本原電は、近く国の原子力安全・保安院に調査の計画を報告したうえで、改めて現地で地層などの調査を行うなどして今後の対応を検討することにしています。

JAPC will report to NISA shortly with the plan for the survey, and will study the strata to decide what to do.

日本原電は「調査の結果によっては想定している最大の地震の揺れや原発の耐震性など、さまざまなことに影響するので慎重に調べたい」と話しています。

JAPC says, "The result of the survey may affect various issues such as expected maximum earthquake and seismic stability of the plant. We would like to proceed very cautiously."

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