KARIWA VILLAGE — Japan resumed operations at the No. 6 reactor of the Kashiwazaki-Kariwa Nuclear Power Station and simultaneously advanced plans for a permanent high-level radioactive waste disposal site on Minamitorishima island. Minamitorishima is a remote Pacific island located south of Tokyo.
The Kashiwazaki-Kariwa facility is the largest nuclear power plant in the world. Tokyo Electric Power Company Holdings operates the plant and installed filtered venting systems and hydrogen explosion prevention equipment there. The cooling pool at the Kashiwazaki-Kariwa No. 6 reactor is 88 percent full of spent nuclear fuel. The Federation of Electric Power Companies of Japan reports that cooling pools at the Kashiwazaki-Kariwa plant will reach capacity in five years.
Takeyuki Inagaki, Kashiwazaki-Kariwa General Manager, stated, "Without solid fuel management plans, our power generation will stall sooner or later." Industry Minister Ryosei Akazawa requested that the Ogasawara village government conduct a feasibility study for a waste disposal site on Minamitorishima. Akazawa said, "With a lot of spent fuel accumulating at nuclear power plants across the country, a final disposal of radioactive waste is a crucial challenge that must be resolved."
Japan maintains a national policy to recycle spent nuclear fuel to recover plutonium and uranium. However, Japan's nuclear fuel reprocessing infrastructure lacks the capacity to process all currently generated spent fuel. A reactor designed for plutonium reuse ceased operations without meeting its intended design goals. Cooling pools at 17 Japanese nuclear power plants contained over 17,000 tons of spent fuel as of December 2025.
Fifteen of Japan's 54 nuclear reactors have restarted operations since the March 2011 Fukushima disaster. That disaster involved a 9.0 magnitude earthquake, a subsequent tsunami, and core meltdowns at three reactors operated by Tokyo Electric Power Company Holdings. Approximately 160,000 residents evacuated from the Fukushima region following the 2011 disaster. Prime Minister Sanae Takaichi supports expanding Japan's operational nuclear reactor capacity.
Lila Okamura, a professor at Senshu University, said, "Japan has to deal with massive and largely unknown high-level nuclear waste from the Fukushima disaster." Okamura added, "For a generations-long project, Japan should plan carefully and not rush the current plan that is full of uncertainties." Developing a permanent underground nuclear waste disposal site in Japan requires approximately 100 years of construction.
Minamitorishima is a government-owned territory located approximately 2,000 kilometers south of Tokyo with no permanent residents. Minamitorishima is the fourth location selected for a feasibility study since Japan initiated its disposal site search in the early 2000s. Municipalities participating in the initial phase of the disposal site review process are eligible for up to 2 billion yen in government subsidies, with an additional 7 billion yen available for advancing to the subsequent review phase. Finland will open the first permanent spent nuclear fuel disposal facility in 2026.