The Kashiwazaki-Kariwa plant
In September 2013, Tepco sought approval from Japan’s Nuclear Regulation Authority (NRA) for the design and construction plans of units 6 and 7 at Kashiwazaki-Kariwa. These 1,356-megawatt Advanced Boiling Water Reactors, operational since 1996 and 1997, were the first of their kind proposed for restart in Japan. Tepco submitted details on safety enhancements for both units and the broader site.
The NRA granted permission to restart units 6 and 7 in 2017. However, in early 2021, Tepco reported issues with intruder detection equipment and unauthorized ID card use at the site. Consequently, in April 2021, the NRA issued an order prohibiting nuclear fuel movement until security improvements were verified. This restriction was lifted in December 2024 after inspections confirmed enhanced measures.
In April 2024, Tepco completed loading fuel into unit 7, aiming for a restart by summer. However, additional anti-terrorism safety measures, required by October 2025, could not be implemented in time. The company stated: “As the installation deadline for the Specially Designated Severe Accident Response Facilities approaches on 13 October 2025, we have decided to suspend the test operation of the reactor itself, as we will be removing the loaded fuel without conducting inspections involving critical reaction operations.”
Fuel removal from unit 7 is scheduled to begin on 14 October 2025, with 872 nuclear fuel assemblies to be transferred to a used fuel storage pool over approximately two weeks, starting 21 October, according to Jiji Press. The completion of an anti-terrorism facility, necessary for the restart, is not expected until August 2029.
Tepco is now focusing on restarting unit 6, where fuel loading was completed in June 2024. Unit 6 has until September 2029 to implement similar anti-terrorism measures, allowing potential operation pending local approval. This shift prioritizes operational readiness while ensuring compliance with safety standards.
The company’s efforts reflect a commitment to maintaining safety and regulatory compliance at Kashiwazaki-Kariwa. By adjusting its strategy, Tepco aims to support Japan’s energy needs while addressing technical and regulatory challenges. The focus on unit 6 underscores a practical approach to achieving operational milestones in the near term.
