Fuel loading under way at Kashiwazaki-Kariwa unit 6

Wednesday, 11 June 2025

Japanese utility Tokyo Electric Power Company announced that it has begun loading fuel assemblies into the core of unit 6 at its Kashiwazaki-Kariwa nuclear power plant ahead of its restart. The unit looks likely to be restarted before unit 7, into which fuel was loaded last year.

Fuel loading under way at Kashiwazaki-Kariwa unit 6
Fuel loading at Kashiwazaki-Kariwa 6 (Image: Tepco)

A total of 872 fuel assemblies will be transported from the used fuel storage pool to the core of the 1356 MWe Advanced Boiling Water Reactor. It is expected to take about two weeks to complete the loading process.

"We will continue to carefully load the reactor with fuel until the last fuel assembly has been loaded," Tokyo Electric Power Company (Tepco) said. "An announcement will be made after all fuel loading has been completed."

Tepco applied for Nuclear Regulation Authority (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, respectively, 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. However, in early 2021, the company notified the NRA of malfunctions in intruder detection equipment on the Kashiwazaki-Kariwa site. In addition, it reported the unauthorised use of an ID card. In April 2021, 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. This order was lifted in December 2023 after inspections confirmed that measures had been enhanced at the site.

Additional regulatory inspections will still be required before Kashiwazaki-Kariwa units 6 and 7 - which have been offline since March 2012 and August 2011, respectively - can resume operation. 

Tepco announced in April 2024 that it had completed loading fuel into unit 7, which it aims to restart as early as this summer. That unit, however, would have to be taken offline again in October to implement anti-terrorism safety measures.

Tepco has until September 2029 to implement these measures at unit 6, and it could continue operating until that time, pending local approval.

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 would increase the company's earnings by an estimated JPY100 billion (USD706 million) per year.

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