In a concerning development, the restart of the world’s largest nuclear power plant, Japan’s Kashiwazaki-Kariwa facility, has been suspended just a day after operations commenced. The decision came after a safety alarm was triggered during the startup procedures for reactor number six.
According to the plant’s operator, Tokyo Electric Power Company (Tepco), the alarm was linked to malfunctioning electrical equipment connected to the control rods, which are crucial for the safe operation of the reactors. Tepco has stated that they do not yet know how long it will take to resolve the issue, with site superintendent Takeyuki Inagaki telling 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.”
The Kashiwazaki-Kariwa plant, located in Niigata prefecture approximately 220 km northwest of Tokyo, is the world’s largest nuclear power plant by potential generating capacity. Only one of its seven reactors had been scheduled to restart, with the No. 6 reactor alone capable of generating around 1.35 million kilowatts of electricity – enough to power more than a million households in the Tokyo region.
The facility was taken offline in 2011 after the devastating Fukushima Daiichi nuclear disaster, which was triggered by a 9.0-magnitude earthquake and tsunami. Japan subsequently shut down most of its nuclear fleet amid public opposition and tighter safety regulations. In recent years, however, the government has moved to revive nuclear power to reduce reliance on fossil fuels, cut emissions, and meet rising electricity demand.
The restart of Kashiwazaki-Kariwa had already faced significant political and public opposition. In December 2025, a vote in the Niigata Prefectural Assembly removed the final hurdle for the plant’s reopening, despite around 60% of local residents opposing the decision. Protesters outside the assembly building held banners reading “No Nukes” and “We oppose the restart of Kashiwazaki-Kariwa,” with one 77-year-old demonstrator from Niigata City, Kenichiro Ishiyama, stating, “If something was to happen at the plant, we would be the ones to suffer the consequences.”
This latest setback highlights the technical and political challenges facing Japan’s efforts to revive its nuclear power industry as it seeks to achieve its target of carbon neutrality by 2050. The suspension of the Kashiwazaki-Kariwa restart will undoubtedly reignite the ongoing debate over the role of nuclear energy in the country’s energy mix and the safety concerns of local communities.
