原発と活断層 規制委は説明責任を果たせ

The Yomiuri Shimbun (Dec. 23, 2012)
Nuclear Regulation Authority too hasty in evaluating faults?
原発と活断層　規制委は説明責任を果たせ（12月22日付・読売社説）

A Nuclear Regulation Authority (NRA) expert team has announced its view that crush zones on the premises of the Higashidori nuclear power plant in Aomori Prefecture are active faults that could cause earthquakes.
　東北電力東通原子力発電所（青森県東通村）敷地内の断層（破砕帯）について、原子力規制委員会の専門家会合が、「地震を起こす活断層」との見解をまとめた。

In light of this view, restarting the plant's reactor early now appears to be difficult.
　東通原発を早期に再稼働させることは難しくなったと言える。

This is a serious matter for Tohoku Electric Power Co., the operator of the nuclear power plant, as it had put its hopes on the restart as the key to recovering its power supply capacity after suffering extensive damage to its facilities from the Great East Japan Earthquake.
　東日本大震災で設備を多数損傷した東北電は、東通原発の再稼働を供給力回復の切り札と期待していただけに、深刻な事態だ。

The faults in question extend along the plant site, coming as close to the reactor as 200 meters. Tohoku Electric had asserted they were formed after layers slipped due to changes in underground water levels. However, the five-member team of experts led by Kunihiko Shimazaki, acting chairman of the NRA, unanimously dismissed the utility's assertion.
　問題とされる断層は、原子炉の２００メートルほど脇を通っている。東北電は、「地下水による地盤のずれ」と説明してきた。だが、規制委の島崎邦彦委員長代理を座長とする専門家会合の５人全員が、東北電の解釈を否定した。

If the faults move in the way the team has predicted, the reactor's safety equipment would inevitably be undermined.
　専門家会合の見解通りに、この断層が動けば、原子炉の安全設備への影響は避けられない。

Nothing is more important than securing the safety of the reactor. Tohoku Electric likely will be urged to thoroughly conduct research and risk assessments as well as to drastically review the seismic resistance of the reactor and other nuclear facilities. Such an overhaul could force the company to carry out reinforcement work, depending on the results of further surveys.
　安全の確保は何より大切だ。今後、東北電は、断層の徹底的な調査と評価、原子炉など施設の耐震性の抜本的な見直しを迫られるだろう。結果次第で、補強工事を求められる可能性もある。

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Stable power supply also needed

In the meantime, Tohoku Electric needs to make every effort to secure a stable power supply so as not to disrupt people's daily lives and business activities.
　国民生活や企業活動に支障を来さないよう、東北電は安定電源の確保に万全を期す必要がある。

On Dec. 10, the expert team reached an agreement that a crush zone directly under a reactor of the Tsuruga nuclear power plant in Fukui Prefecture, operated by Japan Atomic Power Co., is highly likely to be an active fault. In such a case, the reactor could be ordered to be decommissioned, but no such active fault has been found directly under the reactor at the Higashidori plant.
　規制委の専門家会合は１０日にも、日本原子力発電敦賀原発について「原子炉直下に活断層がある」と判定した。一方、東通原発では、廃炉の可能性がある原子炉直下の活断層は確認されていない。

Dissatisfied with the expert team's view, Tohoku Electric reportedly intends to make counterarguments.
　東北電は、専門家会合の見解を不満とし、反論する方針だ。

In addition to faults on the premises of the Higashidori plant, the team has also warned that a huge peripheral fault, more than 80 kilometers long in the nearby seabed, could be active.
　専門家会合は、敷地内の断層に加え、東通原発の目前の海底にも全長８０キロ・メートル以上の巨大活断層がある可能性を指摘した。

If this fault moves, the whole Shimokita Peninsula where the plant is located could be affected. Discussions are likely to be sparked also over the quake resistance of Japan Nuclear Fuel Ltd.'s Rokkasho plant for reprocessing spent nuclear fuel.
　これが動けば、東通原発がある下北半島全体に影響が及ぶ。日本原燃の使用済み核燃料再処理工場などの耐震性も議論になろう。

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Seismology not perfect

Meanwhile, we must not forget that seismology is an immature field. Due consideration is needed over whether the NRA should launch full-fledged research.
　地震学は未熟な学問であることを忘れてはならない。今後、規制委として調査すべきかどうか、慎重な検討が必要である。

Risk assessments of faults in and near nuclear power plants will affect respective regional economies and local residents' lives. People have indeed been increasingly vocal in expressing such concerns.
　各原発の断層評価は、立地地域の経済や住民生活も左右する。不安の声は拡大している。

The regulatory body has the responsibility to explain how its expert team conducted research and evaluated findings in detail, but its efforts have been far from satisfactory in this regard.
　調査、評価の内容について、規制委は丁寧に説明する責任があるが、その取り組みは不十分だ。

The NRA has yet to compile the team's risk assessments in writing. Only information materials full of jargon and video footage showing experts' discussions have been made public.
　規制委は、これまでの評価結果を文書にまとめていない。公開されているのは、専門用語による資料や議論の映像だけだ。

Furthermore, it can be said that the NRA failed to spend enough time exchanging opinions with the utilities concerned and appeared to make assertions one-sidedly.
　しかも、当事者である電力会社との意見交換に十分な時間を割かず、一方的な議論に終始した。

The authority is guaranteed its independence. However, it cannot win public trust with a self-righteous approach.
　規制委は、組織の独立性が保証されている。しかし、独善的な運営では信頼を得られない。

(From The Yomiuri Shimbun, Dec. 22, 2012)
（2012年12月22日01時04分  読売新聞）