NRA cites presence of possible active fault lines underneath facility
Japan’s nuclear watchdog has formally prevented the Tsuruga-2 nuclear power plant in the country’s north-central region from restarting, the first rejection under safety standards that were revised after the 2011 Fukushima disaster.
The Nuclear Regulation Authority said the unit, in Fukui Prefecture, is “unfit” for operation because owner and operator Japan Atomic Power Company (JAPC) failed to address safety risks stemming from the presence of possible active fault lines, which can potentially cause earthquakes, underneath it.
Tsuruga-2, a 1,108-MW pressurised water reactor unit that initially began commercial operation in 1987, is the first reactor to be prevented from restart under safety standards adopted in 2013 based on lessons from the 2011 Fukushima-Daiichi meltdowns following a massive earthquake and tsunami.
Those standards prohibit reactor buildings and other important facilities being located above any active fault.
JAPC has maintained that its own analysis has shown that the fault is not active and does not extend under the unit.
In September the NRA approved a draft report which recommended that Tsuruga-2 does not meet the stricter regulations.
Recent press reports in Japan said the NRA had decided Tsuruga-2 could not be restarted because it could not rule out the possibility that a fault line running under the reactor building is connected to adjacent active fault lines.
“We reached our conclusion based on a very strict examination,” NRA chairperson Shinsuke Yamanaka told reporters.
‘Data Coverups And Mistakes’ By Operator
The verdict comes after more than eight years of safety reviews that were repeatedly disrupted by data coverups and mistakes by the operator, Yamanaka said. He called the case “abnormal” and urged the utility to take the result seriously.
An older unit at Tsuruga, the 340-MW Tsuruga-1 boiling water reactor, began commercial operation in 1970 and was permanently shut down in 2015.
Before the Fukushima disaster Japan’s fleet of 54 nuclear plants generated about 30% of the country’s electricity, but were all shut down for safety checks following the accident.
Among the 33 operable nuclear reactors in Japan, 13 have now resumed operations after meeting post-Fukushima safety standards. The restarted plants are: Sendai-1 and -2, Genkai-3 and -4, Ikata-3, Mihama-3, Ohi-3 and -4, Onagawa-2 (temporarily offline) and Takahama-1, -2, -3 and -4.
In October, Japan’s new economy minister said the country will need to maximise the use of existing nuclear power plants because AI and data centres are expected to boost electricity demand.
Yoji Muto said the new administration will plan restarting as many reactors as possible so long as they are safe.
Muto’s comments point to a continuation of former prime minister Fumio Kishida’s policy that moved Japan back towards nuclear energy as a major power source.
