4 Mars 2016
March 4, 2016
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.
March 4, 2016
THE ASAHI SHIMBUN
A Nuclear Regulation Authority panel has concluded that an active fault line likely runs under a reactor at the idled Shika nuclear power plant, which could threaten the reactor with decommissioning if the findings are confirmed.
The NRA panel of experts compiled its conclusions on March 3 regarding a study into the Shika plant in Ishikawa Prefecture.
"It is rational to interpret the fault (under the No. 1 reactor) as active," the panel said.
The panel is comprised of four outside specialists on geological faults and Akira Ishiwatari, an NRA commissioner.
Hokuriku Electric Power Co., the operator of the plant, intends to contest the panel's findings. The utility faces the possibility of having to mothball the No. 1 reactor if an active fault is confirmed to run under an important facility of the plant.
New safety standards for nuclear plants, which were put into effect after the March 2011 Fukushima nuclear disaster, prohibit major facilities in locations that lie above an active fault.
The panel plans to submit a report of its findings to the NRA in the near future. The NRA is expected to handle the report as "significant findings."
A final determination on whether active faults lie under the Shika plant will be made during safety screenings that will be conducted under the new standards.
The focus of the study was on three faults that run under the plant.
In the summer of 2015, the expert panel compiled a draft report that said, "The possibility of an active fault cannot be denied."
An additional expert asked to evaluate that draft concurred with the findings.
At the March 3 meeting, the panel examined the S-1 fault that runs beneath the No. 1 reactor building. The panel looked over detailed sketches of the geographical formation made when the nuclear plant was being constructed.
That led to the wording, "It is rational to interpret the fault (under the No. 1 reactor) as active," supporting past findings about the fault.
The panel indicated that its assessment was made based on a limited number of documents and called on Hokuriku Electric Power to provide additional data.
The panel also looked at the S-2 and S-6 faults, both of which run under important facilities of the No. 1 and No. 2 reactors. The panel concluded there was the possibility that those two faults were also active.
Such findings would mean that the No. 2 reactor could also not meet the new safety standards unless major anti-quake measures were implemented.
On March 3, Akizumi Nishino, an executive vice president with Hokuriku Electric Power, insisted that none of the faults were active and indicated that the utility would challenge the findings during safety screenings for the No. 2 reactor. He also said the company will seek to have a safety screening for the No. 1 reactor as well.
A major question will be whether Hokuriku Electric Power can submit additional geological data that can overturn the findings of the expert panel.
(This article was written by Masanobu Higashiyama and Koji Kitabayashi.)
jalexia 05/11/2016 11:10