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Utilities aim to overturn NRA expert panel's fault assessment

With the latest draft report from an expert panel at the Nuclear Regulation Authority (NRA), which pointed out the possibility of an active fault running beneath the Shika Nuclear Power Plant in Ishikawa Prefecture, fault assessments for all nuclear plants that face questions about their geological safety have been reported. The operators of these nuclear stations are now looking to overturn the panel's judgment in the NRA's safety screening process.

Of 10 nuclear reactors at six nuclear power plants, three stations, including the Shika plant operated by Hokuriku Electric Power Co., have been judged to be likely situated above active faults. As the nuclear plant operators have raised objections to the panel's assessment results, the focal point of future safety screenings is whether they will be able to prove the panel's conclusion wrong.

The NRA had established an on-site field survey team with experts and carried out investigations of the six nuclear plants, over which the organization's predecessor the Nuclear and Industrial Safety Agency claimed that additional screening was necessary.

In addition to the No. 1 and No. 2 reactors at the Shika nuclear plant, the expert team recognized the possibility of active faults under the No. 2 reactor at Japan Atomic Power Co.'s Tsuruga nuclear station in Fukui Prefecture and the No. 1 reactor at Tohoku Electric Power Co.'s Higashidori nuclear power plant in Aomori Prefecture.

The new regulatory standards for the operation of nuclear power plants adopted in the wake of the 2011 Fukushima nuclear disaster forbid construction of key facilities such as a nuclear reactor right above an active fault. Since the No. 1 reactor at the Shika plant and the No. 2 reactor at the Tsuruga plant have been judged to be possibly located directly above active faults, they face higher chances of being decommissioned.

As for the No. 2 reactor at the Shika plant and the No. 1 reactor at the Higashidori plant, they are located near active faults, meaning that drastic anti-seismic reinforcement measures or relocation of facilities is necessary. This will likely push back the timing of the restart for these nuclear reactors.

Hokuriku Electric applied to the NRA for safety screening for the No. 2 reactor at the Shika nuclear plant in August 2014, and the nuclear watchdog will debate on the existence of an active fault at the safety inspection.

Meanwhile, the utility released a comment following the March 3 draft report on the Shika nuclear plant, saying, "The draft report is far from acceptable. We will submit new geological data to back our argument." The company also plans to apply for a safety inspection of the No. 1 reactor at the Shika plant, which was pointed out to be located directly above an active fault.

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