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2012年12月23日 (日)

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.

In light of this view, restarting the plant's reactor early now appears to be difficult.

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.

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.

If the faults move in the way the team has predicted, the reactor's safety equipment would inevitably be undermined.

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.


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.

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.

Dissatisfied with the expert team's view, Tohoku Electric reportedly intends to make counterarguments.

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.

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.


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.

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.

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.

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.

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.

The authority is guaranteed its independence. However, it cannot win public trust with a self-righteous approach.

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


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