Japan Nears Restart of Kashiwazaki Kariwa, Nuclear Power Returns

Niigata prefectural officials are preparing to endorse the restart of the Kashiwazaki Kariwa nuclear power plant, a seven unit facility operated by Tokyo Electric Power Company that has been offline since the March 2011 earthquake, tsunami and the Fukushima Daiichi crisis. The decision would clear the way for the first full scale reopening of a Japanese nuclear station since that disaster and would be a central test of the national push to rebuild nuclear capacity.

Tokyo Electric Power Company has completed extensive safety work at the site and has installed nuclear fuel in Unit 6, a step that company statements indicate makes that unit ready to begin operations at any time pending local approvals and final checks. Units 6 and 7 were cleared by Japan's Nuclear Regulation Authority in December 2017 under the post crisis regulatory regime that tightened standards for design and emergency preparedness.

Local clearance is the immediate hurdle. Niigata's technical committee issued a report finding no safety issues on a lengthy checklist, and the prefectural governor, Hideyo Hanazumi, and the prefectural assembly are the final arbiters of the restart. Different local reports project slightly different calendars, with some anticipating a January 2026 return to service and others citing March 2026 as a target. Officials have not announced a precise date as final paperwork and conditional approvals remain to be completed.

The restart follows a program of major upgrades at Kashiwazaki Kariwa. TEPCO has invested about 1.2 trillion yen in safety measures that include a roughly 15 metre seawall and upgraded backup systems intended to prevent flooding and maintain core cooling under extreme conditions. The operator's role in the Fukushima accident continues to weigh heavily on public opinion, and the plant's reopening will test whether investments and regulatory reassurances are sufficient to restore broader confidence.

At a national level the move reflects a broader policy reorientation. Nuclear power accounted for roughly 25 percent of Japan's electricity in 2010, collapsed to about 1 percent by 2015 as reactors were taken offline, and has since recovered to about 10 percent as restarts and new rules have been implemented. A 2023 law allowing reactors to operate beyond a previous 60 year limit has further expanded the pathway for long term nuclear capacity.

The immediate economic implications are substantial. Restarts would reduce reliance on imported fossil fuels, narrowing Japan's trade deficit exposure to volatile liquefied natural gas and oil markets and lowering power sector emissions relative to thermal alternatives. For the electricity market, adding gigawatts of nuclear baseload capacity would ease price pressure in winter peak months and alter investment incentives for renewables and storage.

But risks remain. Operational incidents at Fukushima continue to be a reminder of long term liabilities. As recently as August 2024 radioactive water was discovered leaking at Fukushima Daiichi unit 2, underscoring ongoing technical and reputational challenges in the industry.

As prefectural deliberations move forward, the restart of Kashiwazaki Kariwa will be watched closely by energy markets, regulators and communities across Japan. A successful, incident free return to service would advance the government goal of stabilizing supply and meeting climate targets, while any new problems would reinforce public skepticism and complicate the country’s energy transition.