Nuclear Regulation Authority to probe faultlines beneath Tsuruga plant

The Nuclear Regulation Authority is planning to probe faultlines beneath the Tsuruga nuclear power plant in Fukui Prefecture on Dec 1 and Dec 2.

The plant will be the second site to be checked following a probe into the faultline beneath the Oi plant last week.

The two reactors at the Tsuruga plant, which is owned by Japan Atomic Power Co, are currently offline. The team of experts will probe the faultlines that run beneath it to see if they are active and to gauge the seismic risk, Fuji TV reported.

At Tsuruga, the team will try to establish the likelihood of tectonic plates shifting in response to movement from an active fault called Urazoko. During a hearing session in July, seismologists strongly criticized past reports by electric power companies, and the central government, that had ruled out the existence of active faults around the reactors. The Nuclear and Industrial Safety Agency recommended further study of the Shiraki-Nyu fault, which is also recognized as active and runs through Fukui Prefecture.

Kansai Electric Power Co. and the Japan Atomic Energy Agency have maintained that the faultlines show no signs of recent activity. They also deny the possibility that plates could move along those fault lines in response to movement along the active Urazoko fault.

The investigative team currently consists of five geological experts, including NRA Commissioner and seismologist Kunihiko Shimazaki. If the authority decides the reactors are situated above active faults, construction work and plans to restart the reactors may be scrapped.

The government has been reviewing risks posed by active faults after the crisis last year at the Fukushima Daiichi nuclear power plant. Tsuruga reactor 1 was started in 1970, following which the Urazoko fault was confirmed to be active in 2008.

The NRA was established in September of this year, following which it conducted its first survey of potentially active faults near Kansai Electric Power Co's Oi plant, also in Fukui Prefecture, earlier this month. The authority has yet to announce its findings.

There has been a history of safety scares at the Tsuruga plant. In March 1981, drainage from the No. 1 reactor caused a release 16 tons of radioactive primary cooling water. The spill was initially covered up, and then later revealed in April of the same year. On 2 May 2011, officials announced higher than normal levels of radioactivity in the water cooling stores. Following that, a fire broke out in the No. 1 reactor on the evening of 12 November 2011.

On Nov 8, 2011, a group of 40 citizens of Otsu Prefecture filed a law suit against Japan Atomic Power Company and requested a provisional court order to postpone the proposed restart of the two reactors at the Tsuruga plant on the basis that Lake Biwa, which provides drinking water to Kansai, could be contaminated should a nuclear accident occur at the plant.

The plaintiffs argued that the Fukushima disaster proved that existing safety regulations at the 40-year-old site were insufficient and that reactors should remain shut down until the cause of the disaster in Fukushima had been fully investigated.

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