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Fault under Shika nuclear reactor likely to be active: NRA expert panel

The Shika Nuclear Power Plant is seen in Shika, Ishikawa Prefecture, in this Nov. 2, 2011, file photo. (Mainichi)

An investigative panel of experts with the Nuclear Regulation Authority (NRA) compiled a new draft report on March 3 in which it says that a fault running just below the No. 1 reactor at the Shika Nuclear Power Plant in Ishikawa Prefecture is likely to be active.

    In the report, the panel says, "It is reasonable to understand that the fault had moved." In its first draft report prepared in July 2015, the group of experts had pointed to the possibility of the fault being active.

    The new regulatory standards 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. Unless Hokuriku Electric Power Co., the operator of the Shika plant, can overturn the NRA expert group's conclusion, it will become increasingly likely that the No. 1 reactor will be decommissioned.

    Furthermore, as for two other faults running right below a key facility of the No. 2 reactor that has been going through NRA safety screening, the draft report said, "There is a possibility that they had moved." Using as strong a language as what was used for the No. 1, reactor, the expert panel pointed out the possibility of the fault being active. Reactivation of the No. 2 reactor will likely be delayed substantially because there will be even a higher possibility of it being unable to clear the NRA screening process unless large-scale work such as relocation of its facilities is carried out.

    The investigative panel is to draw up a formal report and submit it to the NRA. If Hokuriku Electric were to seek to reactivate the reactors, the NRA would conduct safety screenings on them again to determine whether the faults are active. If the faults are confirmed to be active after the screening, the No. 1 reactor is expected to be decommissioned.

    Hokuriku Electric is planning to apply for NRA screening of the No. 1 reactor as well. In that case, attention will be focused on whether the utility will be able to show new data to overturn the NRA's final conclusion during the fresh round of screening by the nuclear watchdog.

    There are three faults in question: the 780-meter-long "S-1" fault situated just below the No. 1 reactor; and the "S-2" and "S-6" faults just beneath cooling pipes for releasing sea water, extending a combined total of 550 meters. Hokuriku Electric had insisted that none of the faults are active. After compiling a draft report in July 2015 that said the possibility of the faults being active "cannot be denied," the NRA expert group heard the opinions of other experts.

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