Unit 6 of the Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture has resumed commercial operation for the first time in 14 years, marking the first restart of a Tokyo Electric Power Company (TEPCO) reactor since the Fukushima Daiichi accident. This could signal a long-awaited turning point for Japan’s stalled nuclear energy sector.
Unit 6 is an advanced boiling water reactor (ABWR) designed to withstand strong earthquakes. With a generating capacity of 1.356 million kilowatts, it serves as a key power source for the greater Tokyo region. Its return to operation should help ease concerns about electricity shortages.
Resuming commercial operation is expected to strengthen TEPCO’s financial performance and, in turn, help accelerate the ongoing decommissioning of the Fukushima Daiichi plant.
Setbacks and Costs
Fifteen years have passed since the Fukushima accident. Japan’s nuclear power sector, affected by the then-Democratic Party government’s anti-nuclear policies following the disaster, saw the number of reactors fall from 54 to 33 due to decommissioning decisions and other factors. Of those remaining, only 15—including Kashiwazaki-Kariwa Unit 6—have been restarted.
To compensate for the lost output from idled plants, Japan turned to imported fossil fuels for thermal power generation. The cost has been enormous, draining trillions of yen from the economy each year and placing a sustained burden on households and industry alike.
The rest of the world, however, has moved in the opposite direction over the same period. According to the Japan Atomic Industrial Forum, 87 reactors have been constructed and brought into operation globally since 2011.
Units 5, 6, and 7 of Tokyo Electric Power Company’s Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture, November 2025.
Rising Demand and Shifting Views
Russia’s invasion of Ukraine and ongoing instability in the Middle East have further sharpened the focus on energy security, reinforcing nuclear power’s appeal as a stable, domestic source of electricity.
For Japan, a resource-poor island nation, nuclear power holds particular strategic value. A single load of uranium fuel can keep a reactor running for years, effectively making it a quasi-domestic energy source. Unfortunately, this recognition has yet to take firm root at home. An excessive focus on criticism risks obscuring the very real consequences of abandoning nuclear energy altogether.
Electricity demand, meanwhile, is changing rapidly. The explosive growth of artificial intelligence, the expansion of data centers, and efforts to develop a domestic semiconductor industry are all expected to drive significant increases in power consumption. In this emerging landscape, nuclear power’s role is becoming more important than ever.
Even in Europe, a shift in thinking is underway. Countries such as Germany moved away from nuclear power in the wake of Fukushima, but a reassessment is now clearly visible. Italy is also reorienting toward nuclear energy.
At an international conference on March 10, European Commission President Ursula von der Leyen stated plainly that abandoning nuclear power had been a strategic mistake for Europe. Meanwhile, the United States is pushing ahead with next-generation reactor designs and small modular reactors (SMRs).
Japan’s current Strategic Energy Plan calls for maximizing both renewable energy and nuclear power. The direction is clear—what is needed now is the will to follow through.
On the industry and research side, progress is being made. Kansai Electric Power is exploring the construction of next-generation reactors, while the Japan Atomic Energy Agency is advancing research into high-temperature gas reactors capable of both power generation and hydrogen production.
Regulation Challenges
A key concern is the unusually long safety reviews conducted by the Nuclear Regulation Authority. By contrast, regulators in the US—highly regarded internationally—are actively reforming their processes to speed up reviews. Japan would do well to follow suit.
The country’s regulatory framework can also be unnecessarily rigid. One telling example is the rule requiring anti-terrorism facilities at nuclear plants to be completed within five years. Failing this, utilities must shut down reactors even if they are already operating safely.
Although the regulator decided to revise this rule this month, it had already led TEPCO to delay the planned restart of Kashiwazaki-Kariwa Unit 7 and instead proceed with Unit 6. Tohoku Electric Power’s Onagawa Unit 2 in Miyagi Prefecture, which would otherwise have been forced to shut down at the end of this year, will now be able to continue operating under the revised system.
Geological Disposal
The restart of Kashiwazaki-Kariwa Unit 6 is an encouraging step toward ending Japan’s long stagnation in nuclear policy. However, sustaining this momentum will require tackling a deeper structural challenge: establishing a complete domestic nuclear fuel cycle.
This means, first and foremost, accelerating the completion of Japan Nuclear Fuel Limited’s reprocessing plant in Aomori Prefecture. Equally urgent is identifying candidate sites for the geological disposal of high-level radioactive waste produced through spent fuel reprocessing—a task that has been deferred for far too long.
On geological disposal, Masaaki Shibuya, mayor of Ogasawara Village, has effectively indicated acceptance of conducting a literature survey on Minamitorishima. Similar surveys are underway in Genkai in Saga Prefecture, while in two municipalities in Hokkaido, the focus is on whether to proceed to the next stage of preliminary site investigations.
To strengthen Japan’s energy security, strong leadership from the Sanae Takaichi administration will be essential.
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Author: Editorial Board, The Sankei Shimbun
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