Japanese experts still divided over status of allegedly active fault beneath Oi nuclear power plant

Kyodo

A team of experts examining the geological formation under Japan’s sole operating nuclear power plant remained split over whether an active fault runs beneath it after completing their second field survey Saturday.

Four of the group’s five members, including Kunihiko Shimazaki, head of the investigation team and a commissioner of the Nuclear Regulation Authority, indicated they could not rule out the possibility that an active fault runs underneath two restarted reactors at Kansai Electric Power Co.’s Oi power plant in Fukui Prefecture.

But team member and Ritsumeikan University professor Atsumasa Okada said that what the experts had observed “can be explained as a landslide,” noting the rock formation differs from active faults he has previously seen.

Kansai Electric denies that an active fault exists under the Oi complex.

The outcome of the inspection is under the spotlight since the government approved the restart of reactors 3 and 4 at the Oi plant in July, making them the first atomic units to resume operations since the triple meltdown crisis at the Fukushima No. 1 plant last year saw all of the nation’s reactors halted for safety checks.

In Saturday’s survey, the team checked a test trench dug outward from the fracture zone of the F-6 fault, which is suspected of being active, as well as another test trench and the coastal area of the compound. The power station was built on the shores of the Sea of Japan.

While the team will hold an evaluation session early in the new year, its members are seen as unlikely to reach a unified conclusion anytime soon. A large amount of data were gathered Saturday, and the five experts all said they needed time to analyze them thoroughly before reaching a conclusion.

Shimazaki, the group leader, is meanwhile calling for more boring to be conducted in the southern part of the Oi complex under a new survey, which could further delay the team’s final report.

If the F-6 fault — believed to run below the emergency water intake channel of the fully operational No. 3 and 4 reactors — is deemed to be active by the group, the NRA plans to order Kansai Electric to immediately take both units offline.