Japan Approves Restart of World's Largest Nuclear Plant, Kashiwazaki-Kariwa, Marking Major Energy Policy Shift

Niigata Assembly Greenlights Kashiwazaki-Kariwa Restart

On Monday, December 22, 2025, the Niigata Prefectural Assembly officially endorsed the decision to allow the restart of the Kashiwazaki-Kariwa nuclear power plant. This pivotal approval, which followed Governor Hideyo Hanazumi's backing last month, effectively removes the final local political hurdle for the facility, located approximately 220 kilometers northwest of Tokyo, to resume operations. The move represents a significant turning point in Japan's energy strategy, nearly 15 years after the devastating Fukushima Daiichi disaster.

The Legacy of Fukushima and Japan's Energy Reassessment

The Fukushima Daiichi nuclear accident, triggered by a 9.0-magnitude earthquake and subsequent tsunami on March 11, 2011, led to meltdowns at the plant, which was also operated by Tokyo Electric Power Company Holdings (TEPCO). The disaster, rated Level 7 on the International Nuclear Event Scale—the highest severity—resulted in the shutdown of all 54 nuclear reactors across Japan. In the aftermath, Japan's energy policy shifted dramatically, increasing the nation's dependence on imported fossil fuels. The restart of Kashiwazaki-Kariwa, the world's largest nuclear power plant with a total output capacity of 8.2 GW (8,212 MW) from its seven units, is seen as a critical step towards reversing this trend.

Economic and Environmental Drivers for Nuclear Revival

The decision to reactivate Kashiwazaki-Kariwa underscores Japan's renewed commitment to nuclear power as a means to enhance energy security, reduce reliance on costly imported fossil fuels, and meet its decarbonization targets. The Japanese government aims for nuclear power to contribute 20-22% of the country's electricity generation by 2030 and 20% by 2040. TEPCO has reportedly invested 1.2 trillion yen in extensive safety upgrades at the plant, including the construction of a 15-meter seawall, to prevent a recurrence of the 2011 catastrophe.

Path to Operation and Public Concerns

TEPCO is now preparing to reactivate Unit 6 of the Kashiwazaki-Kariwa plant, with a capacity of 1,315 MW, as early as January 20, 2026. This would mark the first time TEPCO operates a nuclear plant since the Fukushima disaster. The restart of just one reactor is projected to boost electricity supply to the Tokyo area by 2%. However, public sentiment remains divided. An October survey in Niigata Prefecture revealed that 60% of residents believed conditions for a safe restart had not been met, and nearly 70% expressed concerns about TEPCO's operational capabilities. On the day of the assembly's vote, approximately 300 protesters gathered outside, holding banners with slogans such as 'No Nukes' and 'We oppose the restart of Kashiwazaki-Kariwa'. In an effort to gain local support, TEPCO has pledged to inject 100 billion yen into the prefecture over the next 10 years.