TEPCO Resumes Commercial Operations at Kashiwazaki-Kariwa Unit 6, the First Post-Fukushima Restart for the Fukushima Operator
Tokyo Electric Power Company restarted commercial operations at the world's largest nuclear plant on April 16, 2026, ending a 14-year shutdown of TEPCO's entire nuclear fleet since the 2011 Fukushima Daiichi accident.
Overview
Tokyo Electric Power Company Holdings (TEPCO) resumed commercial operations of Unit 6 at its Kashiwazaki-Kariwa nuclear power plant on April 16, 2026, ending a shutdown that kept the utility’s entire nuclear fleet offline for more than 14 years after the 2011 Fukushima Daiichi accident. The restart marks the first time a TEPCO reactor has returned to commercial service since the triple meltdown that followed the March 2011 Great East Japan Earthquake and tsunami, and it completes a restart campaign that began in January after the plant cleared its final local political hurdles in December 2025.
Kashiwazaki-Kariwa, located in Niigata Prefecture on Japan’s west coast, is the largest nuclear power station in the world by installed capacity. Its seven boiling-water reactors have a combined output of about 8.2 gigawatts when fully operational, according to Al Jazeera. Only Unit 6 is currently producing power; the remaining six reactors, including Unit 7 which has received regulatory approval to restart, are still awaiting resumption.
What We Know
The path back to commercial operation began on December 22, 2025, when the Niigata Prefectural Assembly backed Governor Hideyo Hanazumi’s decision to consent to the restart of Units 6 and 7. As reported by Al Jazeera, the confidence vote completed the local political process and allowed TEPCO to advance its restart plans. Prime Minister Sanae Takaichi, who had taken office two months earlier, championed the reopening as a pillar of her government’s push to strengthen energy security and reduce dependence on imported fossil fuels.
The restart itself was not smooth. TEPCO initially brought Unit 6 back online on January 21, 2026, at 7 p.m. local time, only to suspend operations hours later after a malfunction in electrical equipment connected to the reactor’s control rod system. According to Al Jazeera’s coverage of the shutdown, a TEPCO spokesperson said the reactor remained stable throughout the incident and that “there is no radioactive impact outside” the facility. The company placed the unit into full shutdown for investigation.
Commercial operations, originally targeted for late February, were delayed by roughly 50 days as TEPCO worked through the control rod fault and a subsequent alarm indicating an electricity leak from the reactor’s generator in mid-March. Unit 6 finally entered full commercial operation at 4 p.m. local time on April 16, after the company completed a final pre-operation inspection that confirmed no abnormalities in the reactor, generator, or turbine at full capacity.
Opposition to the restart remains substantial. Roughly 300 protesters rallied outside the Niigata assembly during the December consent vote, carrying signs reading “No Nukes” and “Support Fukushima,” according to Al Jazeera. Evacuee Ayako Oga told the outlet, “We know firsthand the risk of a nuclear accident and cannot dismiss it.” In the weeks before the January restart, nearly 40,000 people signed a petition opposing the reopening, Al Jazeera reported at the time. TEPCO President Tomoaki Kobayakawa, quoted by Al Jazeera around the January restart, framed safety as “an ongoing process, which means operators involved in nuclear power must never be arrogant or overconfident.”
Context
Japan shut down all 54 of its reactors in the years following the Fukushima Daiichi meltdown, and the country’s nuclear fleet has been restored only gradually. As Al Jazeera reported at the time of the January restart, Kashiwazaki-Kariwa Unit 6 is the 15th reactor to resume operation out of 33 that remain operable. The plant sits on an active fault zone and experienced a strong earthquake in 2007 that damaged equipment and prompted earlier safety reviews; TEPCO has since added a 15-meter tsunami seawall and other upgrades.
The Takaichi government’s energy strategy calls for doubling the share of nuclear generation in Japan’s electricity mix to roughly 20 percent by 2040, with new reactor construction supported by a state funding scheme announced late last year, according to Al Jazeera. The shift follows setbacks in Japan’s offshore wind program and persistent concerns about the cost of liquefied natural gas imports. This follows earlier reporting by The Machine Herald on the growing international coalition backing a tripling of nuclear capacity by 2050.
What We Don’t Know
TEPCO has said it plans to operate Unit 6 for one year until its next planned inspection, but the timeline for restarting Unit 7 — the second reactor approved for resumption — has not been publicly committed. Public opposition, the plant’s seismic setting, and the possibility of further technical faults of the kind that delayed the April restart all remain open variables. The broader question of whether Japan can scale nuclear generation quickly enough to meet the government’s 2040 target, particularly given the decade-long timelines that characterized Kashiwazaki-Kariwa Unit 6’s return, is also unresolved.