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TEPCO restarts Kashiwazaki Kariwa Unit 6
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Earlier today, TEPCO announced that after nearly 15 years, Unit 6 at the Kashiwazaki Kariwa nuclear power station has been restarted. Following approval from Japan’s Nuclear Regulation Authority (NRA), TEPCO withdrew the reactor’s control rods to initiate startup at 7:02 p.m. local time.
Next, the company will work with the NRA to confirm the safe operation of the plant. “We will carefully verify the integrity of each and every plant facility while suitably addressing any issues that arise and conveying information to the public during each step of the startup process,” TEPCO’s statement said.
Background: Kashiwazaki Kariwa, located in Niigata Prefecture on the Sea of Japan, is one of the world’s largest nuclear power plants, with seven reactors that have a combined capacity of nearly 8 GW. The station was completed in 1997, but all units were shut down—along with all other Japanese reactors—following the March 2011 earthquake and tsunami that led to the accident at Fukushima Daiichi nuclear power station.
Japan has slowly been restarting its nuclear fleet, following required extensive inspections, safety enhancements, and equipment upgrades. In addition to NRA approval, Japan’s reactor restart program is seeking approval from local officials. Niigata Prefecture Gov. Hideyo Hanazumi gave his consent in November of last year, and the Niigata Prefectural Assembly backed that decision in December.
Nuclear power is seen as essential to support Japan’s goal of carbon neutrality by 2050.
Units 6 and 7: It has taken years for TEPCO to modify the two largest units at Kashiwazaki Kariwa ahead of this initial startup of Unit 6. The NRA approved initial work on Units 6 and 7 in 2017. According to a statement from TEPCO on December 24 of last year, the review by the NRA began in September 2024 when TEPCO submitted a preoperational confirmation application to the NRA.
During 2025, TEPCO advanced through restart milestones. According to the company, “Fuel was loaded [into Unit 6] on June 21, 2025, after which integrity verifications and pre‑operational operator inspections were completed on October 28, 2025.” These checks, conducted first by TEPCO under its operator‑inspection guidelines and later confirmed by the NRA, are required before the company may introduce actual steam into the plant systems. Today’s restart marks the beginning of steam production.
Next steps: TEPCO included an inspection schedule with their application to the NRA for the startup of Unit 6. In coming days, TEPCO will conduct three inspections: the reactor core isolation cooling system, the high-pressure alternate cooling system, and a general load performance test of the entire system. Commercial operation is targeted for late February.
TEPCO plans to restart Kashiwazaki Kariwa Unit 7 by 2030. The fate of plant’s remaining five units is undecided, though TEPCO has indicated that it might opt to decommission Units 1 and 2.
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