When Tokyo Electric Power Company (TEPCO) brought Unit 6 at Kashiwazaki-Kariwa back online in January, it became the first TEPCO reactor to resume since the Fukushima Daiichi accident. An alarm halted the restart the next day; the unit resumed operation in February and entered commercial service in April. Unit 7 at Kashiwazaki-Kariwa, meanwhile, is not expected to restart before 2029–30, according to the EIA.

Clearly, the restart announcement in January was a bit of a false start. Still, the symbolism was unmistakable: The utility responsible for Fukushima is again operating a nuclear plant, the world’s largest by installed capacity.

The timing was also consequential. The Israeli-Japan strikes on Iran on February 28 and the resulting effective closure of the Strait of Hormuz exposed Japan’s reliance on imported energy. In 2025, the Middle East supplied 94 percent of Japan’s crude oil imports; 93 percent of the country’s crude imports passed through Hormuz, according to Reuters. 

Japan’s exposure to Hormuz through LNG is much smaller: around 6 percent of total LNG imports, according to IEEFA. Yet Japan imports more than 97 percent of the LNG it consumes, and LNG generates about a third of Japan’s electricity, according to the government’s 2025 energy overview. The Hormuz shock therefore mattered both as a direct risk to Japan’s oil supply and as the cause of higher global gas and electricity prices.

The International Energy Agency reported that Japanese wholesale spot electricity prices in the second quarter of 2026 were more than 30 percent higher year on year. Futures in mid-July pointed to prices in the second half of 2026 nearly 40 percent above the same period a year earlier. These are wholesale-market figures, not household bills, but they show how a disruption to a relatively small share of Japan’s direct LNG supply can still transmit through global markets.

Prime Minister Takaichi Sanae has made it clear that the nuclear restart is part of the answer to Japan’s energy uncertainty. She said in March that the newly reopened Kashiwazaki-Kariwa Unit 6, combined with a temporary increase in coal-fired generation, could cut Japan’s LNG imports passing through Hormuz by about 40 percent. 

That logic extends beyond the Gulf. A country dependent on LNG imports for a large share of its electricity is exposed to disruptions elsewhere in the Indo-Pacific, including scenarios involving shipping routes around Taiwan or in the East China Sea. For example, Japan’s continued reliance on Russian LNG has become a problem. The Sakhalin-II supply relationship has become a question of energy security, diplomacy, and policy autonomy. 

The strategic case for nuclear power is therefore not just about decarbonization or energy bills. It is also about preserving Tokyo’s strategic autonomy by reducing its reliance on overseas energy providers. 

Japan’s nuclear energy targets remain well ahead of the fleet it can count on today. The government’s Seventh Strategic Energy Plan set a target for nuclear power to supply about 20 percent of electricity generation in fiscal year 2040. The U.S. Energy Information Administration (EIA) estimated that meeting that target would require up to 30 reactors in operation. As of September 16, the latest date on the Nuclear Regulation Authority’s operating-status register, 11 reactors were classified as “Operation.” 

On August 26, the Green Transformation Implementation Council adopted a package calling for the maximum use of nuclear power, with safety as a prerequisite, as NucNet reported. The plan set out plans to replace two to five reactors in the 2040s and a cumulative 11 to 14 by the 2050s, alongside investment in domestic supply chains for perovskite solar, next-generation geothermal, and offshore wind. 

As Reuters reported, specific measures, including legislative steps, are expected by year’s end. The package is therefore more than a statement of intent, but key details – including the specific sites for nuclear plants – remain to be worked out.

Japan’s government may have a sense of political urgency, but its nuclear companies still lack institutional credibility. In September, an independent inquiry found that Chubu Electric Power, which operates the Hamaoka Nuclear Power Plant in Shizuoka Prefecture, had selectively used seismic-wave data to keep its estimates within internal parameters, despite earlier internal reports of irregularities. The inquiry also found that senior management had pressed staff to restart the reactors as soon as possible, according to Reuters. In response, Chubu said it would withdraw its applications to restart Units 3 and 4 at Hamaoka, and that its president and chairman would resign.

The episode shows what can happen when the commercial and political pressure for speedy restarts overtakes the discipline of safety review. It also gives opponents of restarts a concrete reason to doubt assurances from both utilities and government. Chubu says it may reapply after restructuring its organization and processes. Before it does, the company must show that its internal controls can withstand pressure to produce a favorable answer. Japan’s nuclear regulator, in turn, must be able to demonstrate that review standards are applied independently and transparently.

Public opposition, especially at the local level, is a related issue. Niigata’s governor approved the restart of Kashiwazaki-Kariwa, but a survey conducted before that decision found 50 percent of residents supported restarting Unit 6 and 47 percent opposed it. Nearly 70 percent said they were concerned about TEPCO operating the reactor.

The governor’s approval came with demands for clear safety explanations, evacuation planning, road improvements, and continued monitoring of TEPCO. In other words, local acceptance will require continued action on TEPCO’s part. A serious incident, a poor safety disclosure, or another data scandal at any plant can shape public opinion across the country. 

Three tests will show whether Japan’s nuclear revival can provide a reliable source of energy – especially in large enough quantities to make a meaningful difference for Japan’s energy security. First, can the Nuclear Regulation Authority retain public credibility while the government presses for a faster energy transition? Second, can utilities with past governance failures repair their internal controls and earn the right to re-enter the review process? Third, will the August package’s promised legislation and funding arrive by year’s end, and will the longer-term replacement targets be matched by realistic project timetables and local consent?

Japan’s government can designate nuclear energy a security asset; it cannot legislate the public confidence required for the nuclear revival to proceed.