A reactor at the Tsuruga nuclear station is sitting right above an active fault, a panel of experts under Japan's nuclear regulator has reaffirmed — a move that could force the operator to shut the unit for good.
After the Nuclear Regulation Authority acknowledged last year that the fault in question is active, Japan Atomic Power Co. submitted additional data in an effort to have the ruling overturned.
The panel of experts, however, concluded that the new data offered no evidence to sway the judgment as it compiled a new draft report regarding the fault.
A zone of rock fragments called D-1, running directly beneath the No. 2 reactor at the plant in Fukui Prefecture, "could move in the future," the draft report said.
Under the country's nuclear safety requirements, plant operators are barred from building reactors and other important safety facilities directly above active faults, which are currently defined as those that have moved in the last 120,000 to 130,000 years.
The draft report will likely be finalized by an NRA decision-making panel after making amendments to details — which would make it difficult for Japan Atomic Power to resume the unit's operation.
All of Japan's nuclear reactors are currently offline. To go back online, they must pass the regulator's safety screening process based on tougher regulations adopted in the wake of the 2011 Fukushima triple meltdown.
Japan Atomic Power Vice President Taiki Ichimura said he believes the assessment is not based on specific evidence, describing it as a "one-sided assumption."
"I'm sure we can counter the judgment," he told reporters after the panel meeting, adding that he will ask the NRA for further discussion on the matter.
If the company has to decommission the unit, it would face enormous costs and a loss of asset value.