Tepco applied for NRA approval of its design and construction plan for Kashiwazaki-Kariwa units 6 and 7 in September 2013. It submitted information on safety upgrades across the site and at those two units. These 1356 MWe Advanced Boiling Water Reactors began commercial operation in 1996 and 1997 and were the first Japanese boiling water reactors to be put forward for restart.
In 2017, Tepco received permission from the NRA to restart units 6 and 7. Local government consents are still required before the reactors can be restarted.
However, in January 2021, Tepco notified the NRA that a contractor had accidentally damaged intruder detection equipment at the Kashiwazaki-Kariwa site. The company informed the regulator the following month that some of the functions related to this equipment had been repaired. At that time Tepco said it had also found malfunctions in intruder detection equipment at 12 locations on the site and that alternative measures had been implemented. Tepco later informed the NRA of three further locations experiencing equipment malfunctions. In addition, it reported the unauthorised use of an ID card.
The NRA told Tepco in March 2021 that a preliminary assessment had rated the significance of these security lapses as 'red' - the highest level on its four-point scale of risks in safeguarding nuclear material. This rating implies a large impact on safety functions or performance. The NRA decided to "suspend for the time being" its pre-use inspections, which are required for Tepco to load fuel into Kashiwazaki-Kariwa unit 7.
The following month, the NRA issued an administrative order to Tepco prohibiting it from moving nuclear fuel at the plant until improvements in security measures there have been confirmed by additional inspections.
At the 27 December meeting, the NRA decided to lift the administrative order after inspections confirmed that measures had been enhanced at the Kashiwazaki-Kariwa plant, in Japan's Niigata Prefecture.
Kashiwazaki-Kariwa was unaffected by the March 2011 earthquake and tsunami, which damaged Tepco's Fukushima Daiichi plant, although the plant's reactors were previously all offline for two to three years following the 2007 Niigata-Chuetsu earthquake, which caused damage to the site but did not damage the reactors themselves. While the units were offline, work was carried out to improve the plant's earthquake resistance.
Although it has completed work at the other idled units at Kashiwazaki-Kariwa, Tepco is concentrating its resources on units 6 and 7 while it deals with the clean-up at Fukushima Daiichi. Restarting those two units - which have been offline for periodic inspections since March 2012 and August 2011, respectively - would increase the company's earnings by an estimated JPY100 billion (USD706 million) per year.
"While going back once again to the reflections and lessons learned from the Fukushima Daiichi Nuclear Power Station Accident, we will continue to engage in activities in which all personnel voluntarily engage as we strive to become a nuclear power operator that is trusted by the people of the region and society as a whole," Tepco said.
