Tokyo Electric Power Company Holdings (Tepco) has begun loading nuclear fuel into the reactor at unit 7 the Kashiwazaki-Kariwa plant in Niigata Prefecture after the Nuclear Regulation Authority (NRA)granted approval. However, the timing of the restart remains uncertain. It is expected to take about two weeks of round-the-clock work to complete the loading of 872 fuel assemblies into the reactor vessel. Tepco will confirm the safety by testing the function of control rods and emergency core cooling systems, among other things, for about a month after the loading.
Although Kashiwazaki-Kariwa was unaffected by the March 2011 earthquake and tsunami all seven of the plant’s reactors had been offline for two to three years following the earlier 2007 Niigata-Chuetsu earthquake, which caused damage to the site. Work has since been carried out to improve the plant's earthquake resistance. Tepco applied for NRA approval of its design and construction plan for Kashiwazaki-Kariwa units 6&7 (1356 MWe advanced boiling water reactors) in September 2013.
Tepco submitted information on safety upgrades across the site and at those units, which began commercial operation in 1996 and 1997 and were the first Japanese boiling water reactors to be considered for restart. NRA cleared safety screenings for the two units in 2017 but security breaches and delays in completing safety upgrades caused delays. The plant was found to be vulnerable to unauthorised entry at multiple locations because of defective intruder detection systems and backups, with security flaws discovered since January 2021.
NRA prohibited the transportation or loading of reactor fuel stored at the plant in April 2021 due to insufficient counterterrorism measures, ordering Tepco to take corrective action. In January, NRA confirmed that measures to prevent the leakage of radioactive materials had been enhanced through an additional 4,268 hours of inspections. NRA made the decision based on an assumption that continued improvements can be expected at the plants in terms of both hardware and policy. In terms of policy, Tepco has established a Physical Protection Monitoring Office at the plant under the direct supervision of the company’s President Tomoaki Kobayakawa.
Niigata Governor Hideyo Hanazumi has yet to announce whether he will agree to restart the reactor. Hanazumi has said challenges remain concerning how to evacuate residents if an accident occurs. Meanwhile, mayors in the two municipalities that host the facility support the proposed restart.
Earlier this year, Economy, Trade & Industry Minister Ken Saito, after a meeting with Kobayakawa, noted: “It is extremely important for Tepco to regain the trust it has lost and become an organisation that can improve on its own.” Saito asked Tepco to report on its measures to restore trust early next year.
According to Tepco, restart of Kashiwazaki-Kariwa 6&7 will reduce its fuel costs for thermal power generation, resulting in savings of JPY120bn a year. Currently, Tepco’s electricity rates are 20% higher than those of Kansai Electric Power Co and others.
Image: Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture
