Japan has suspended the restart of the world's largest nuclear power plant merely twenty-four hours after operations commenced, following an alarm that sounded during critical start-up procedures. The abrupt halt at the Kashiwazaki-Kariwa facility in Niigata province marks a significant setback for the nation's ambitious nuclear energy revival programme.
Technical Alarm Triggers Immediate Shutdown
An alert from a monitoring system was triggered while workers were initiating reactor number six at the Kashiwazaki-Kariwa nuclear power plant, prompting operator Tokyo Electric Power Company (Tepco) to immediately halt operations. The company confirmed the reactor remains stable with no radioactive impact detected outside the plant boundaries.
Tepco revealed the issue relates to malfunctioning electrical equipment connected to the control rods, which are absolutely crucial for safe reactor operation. Site superintendent Takeyuki Inagaki told reporters: "We don't expect this to be solved within a day or two. There is no telling at the moment how long it will take. We will for now fully focus on trying to identify the cause of what happened."
Previous Delays and Technical Challenges
This restart had already experienced delays earlier in the week when another technical problem emerged during preparations to remove control rods. Although that issue was reportedly resolved before operations began, the latest alarm demonstrates the persistent technical challenges facing Japan's nuclear infrastructure.
The Kashiwazaki-Kariwa facility, located approximately 220 kilometres northwest of Tokyo in Niigata province, represents the world's largest nuclear power plant by potential generating capacity. Only one of its seven reactors had been scheduled for this initial restart phase. The No. 6 reactor alone possesses the capability to generate about 1.35 million kilowatts of electricity – sufficient to power more than one million households across the Tokyo region.
Historical Context and Political Landscape
The facility was taken completely offline in 2011 following the catastrophic 9.0-magnitude earthquake and tsunami that triggered meltdowns at the Fukushima Daiichi nuclear plant, which was also operated by Tepco. Japan subsequently shut down most of its nuclear fleet amid overwhelming public opposition and substantially tighter safety regulations.
In recent years, the Japanese government has actively moved to revive nuclear power generation to reduce reliance on imported fossil fuels, cut carbon emissions, and meet escalating electricity demand – particularly from data centres and artificial intelligence operations. Fourteen reactors have successfully restarted across Japan since 2011, but Kashiwazaki-Kariwa represents the first Tepco-operated plant to resume operations.
Political Approval and Public Opposition
In December 2025, a vote in the Niigata Prefectural Assembly removed the final political hurdle for the plant's reopening. The assembly passed a vote of confidence in governor Hideyo Hanazumi, who had publicly backed the restart initiative. However, this political settlement faced immediate criticism from opponents.
One assembly member opposed to the restart declared during the session: "This is nothing other than a political settlement that does not take into account the will of the Niigata residents." Outside the assembly building, approximately 300 protesters gathered with banners reading "No Nukes", "We oppose the restart of Kashiwazaki-Kariwa" and "Support Fukushima".
Kenichiro Ishiyama, a 77-year-old protester from Niigata city, expressed his frustration to reporters: "I am truly angry from the bottom of my heart. If something was to happen at the plant, we would be the ones to suffer the consequences."
Divided Public Opinion and Safety Concerns
Public opinion within Niigata remains profoundly divided regarding nuclear restart. According to a September survey, approximately 60 percent of residents oppose the restart, while only 37 percent support it. Earlier this month, seven anti-nuclear groups submitted a petition containing nearly 40,000 signatures to both Tepco and Japan's Nuclear Regulation Authority, citing significant seismic risks at the site.
The proposed restart of Kashiwazaki-Kariwa has been postponed for years due to extensive safety upgrades and substantially tighter security rules implemented after the Fukushima disaster. These include comprehensive measures designed to prevent deliberate attacks on nuclear facilities.
Broader Energy Policy Implications
Japan's former prime minister, Fumio Kishida, has previously emphasised that nuclear energy would play a crucial role in achieving the country's ambitious target of carbon neutrality by 2050. However, Thursday's technical setback starkly highlights the persistent technical and political challenges facing this fundamental policy shift.
The suspension comes exactly as Japan commemorates the anniversary of the Fukushima disaster, serving as a powerful reminder of the complex legacy surrounding nuclear power in the nation. As Tepco works to identify the precise cause of the alarm, the incident raises broader questions about the feasibility and timeline of Japan's nuclear renaissance amid ongoing public scepticism and technical hurdles.
