TEPCO Restarts Kashiwazaki-Kariwa No. 6 Reactor

Tokyo, Jan. 21 (Jiji Press)–Tokyo Electric Power Company Holdings Inc. reactivated the No. 6 reactor at its Kashiwazaki-Kariwa nuclear power station in Niigata Prefecture, central Japan, on Wednesday. The No. 6 unit was brought back online after a hiatus of 13 years and 10 months, becoming the first TEPCO reactor reactivated since the March 2011 triple meltdown at the company’s tsunami-stricken Fukushima No. 1 nuclear plant in northeastern Japan. The Niigata prefectural government agreed to the plant’s restart on the condition that the central government further improves safety, amid the country’s shift in energy policy to making maximum use of nuclear power for electricity generation. Surveys, however, have shown prefectural residents split in their views on the restart. Allaying concerns about nuclear plants is a key challenge, especially after fraud involving earthquake risk data at Chubu Electric Power Co.’s Hamaoka plant in Shizuoka Prefecture, central Japan, came to light earlier this month. The Kashiwazaki-Kariwa plant’s No. 6 unit was initially slated to go back online Tuesday. The restart was postponed, however, after an alarm was not activated during a test on Saturday to remove control rods for suppressing nuclear fission reactions in the reactor. After an investigation revealed an error in the settings for the control rod removal prevention function, TEPCO checked all 205 control rods for similar issues through the early hours of Wednesday. To reactivate the No. 6 reactor Wednesday, TEPCO started to remove control rods a little past 7 p.m. after obtaining approval from the Nuclear Regulation Authority for the unit’s test use. The reactor reached criticality, or a self-sustaining nuclear chain reaction, about an hour and a half later. The plant operator said it will gradually raise the pressure inside the reactor and start power generation and transmission on Jan. 28. As the plant had been offline a long time, TEPCO will briefly suspend the reactor to check for abnormalities before bringing it back online again, conducting a final inspection on Feb. 26 and putting the unit into commercial operations. “We will carefully verify the integrity of each and every plant facility” as this marks the first operation of the reactor in about 14 years, TEPCO said in a statement. “We remain fully committed to demonstrating through actions and results that we are prioritizing safety” at the Kashiwazaki-Kariwa nuclear plant, it added. The Kashiwazaki-Kariwa plant’s seven reactors are boiling water units, the same type as those at the Fukushima No. 1 plant. All of them were halted in March 2012. In March 2024, the Japanese government asked the Niigata prefectural government and others for understanding on reactivating the Kashiwazaki-Kariwa plant. After the prefecture conducted a review of the Fukushima No. 1 plant accident and held hearings, Niigata Governor Hideyo Hanazumi in November 2025 announced that he would allow reactivation, and the prefectural assembly then supported the governor’s decision. Wednesday’s restart brought the total number of reactors brought back online under the NRA’s new safety screening standards, introduced in 2013, to 15. END [Copyright The Jiji Press, Ltd.]