TOKYO — An expert panel of the Nuclear Regulation Authority said Wednesday three faults running beneath the No. 1 reactor and other facilities of Hokuriku Electric Power Co.’s Shika nuclear power plant in Shika, Ishikawa Prefecture, may be active.
Members of the panel agreed on the view that “the possibility that the faults are active cannot be denied.”
The NRA’s new safety standards prohibit the construction of key nuclear facilities such as reactor buildings over active faults.
The No. 1 reactor may have to be decommissioned if the NRA concludes the faults are active. In addition, it also will become difficult to reactivate the No. 2 reactor.
There are eight faults under the nuclear facility site. Among them, it is said that three faults – one called S-1 running beneath the No. 1 reactor and others called S-2 and S-6 located beneath the plumbing system to deliver cooling seawater, which is a key facility – may be active.
The NRA defines active faults as those that have moved in the last 120,000 to 130,000 years. Four external experts serving on the panel concluded that “It was not possible to confirm any evidence to show those faults have moved in the past from the data from the drilling survey conducted by Hokuriku Electric Power Co.”
However, they also examined a diagram showing a fault near a reactor building drawn by the power company before the No. 1 reactor was constructed, and other materials. As a result, the members agreed on the view that “the possibility that the [three] faults have moved in the past cannot be denied.” The panel will draw up a draft evaluation report and compile an official conclusion in the future.
Hokuriku Electric Power Co. applied for safety screening of its No. 2 reactor at the Shika plant in August last year without waiting for the opinions of the expert panel. If the conclusion that the S-2 and S-6 faults located beneath the turbine buildings of the Nos. 1 and 2 reactors are active is not overturned in the safety screening, it will become difficult to reactivate the No. 2 reactor.
“We cannot agree with the view because the panel made many inferences. We’d like to firmly state, in the safety screening and other occasions, that the faults are not active,” Yutaka Kanai, executive vice president of Hokuriku Power Electric Co. said to reporters after the meeting, suggesting that the company would apply for further safety screening of the No. 1 reactor.
The panel has concluded so far that the No. 2 reactor at Japan Atomic Power Co.’s Tsuruga nuclear power plant in Fukui Prefecture sits on an active fault, while it has denied possibilities that faults located beneath Kansai Electric Power Co.’s Oi nuclear power plant and Mihama nuclear power plant, both in the same prefecture, are active.
The Shika nuclear power plant is the only nuclear power plant owned by Hokuriku Electric Power Co. Reactors at the plant are boiling water reactors, the same type as those at Tokyo Electric Power Co.’s ruined Fukushima No. 1 nuclear power plant. The No. 1 reactor started operation in 1993 with an output of 530,000 kilowatts, and the No. 2 reactor began service in 2006 producing 1.358 million kilowatts.