Hello everyone, how are you? Almost everyone has heard that Japan depends on nuclear power plants. In this article, I will look at nuclear energy in Japan and at the relationship the country has built with a source of electricity that remains one of the most contested in the world.
The Fukushima Daiichi accident in March 2011 shows why the debate remains intense. More than fifteen years later, part of the site is still restricted, decommissioning continues, and the treated water used to cool the damaged reactors is being released under international monitoring. I will go through the topic calmly, from the beginning of the program to the reactors that are running today.
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Japan and its energy industry
Japan's first commercial nuclear reactor began operating in 1966, and nuclear energy became a national strategic priority in 1973. Even though it is the only country to have suffered the effects of nuclear weapons in wartime, Japan has used nuclear technology for peaceful electricity generation. The Fukushima accident put that priority under review, but the government confirmed it. The decision is not simple to undo, because the country has few domestic energy resources and a large industrial base.
Until 2011, Japan generated around 30% of its electricity from its reactors, and the plan was to reach at least 40% by 2017. Within 14 months of the accident, all 54 reactors in the country were offline. The current target is around 20% by 2030, from a smaller and older fleet.
According to the World Nuclear Association, Japan has 33 reactors classified as operable, with a combined capacity of about 31.7 GW. Fifteen have restarted since 2015, and seven are at some stage of the restart review. Kashiwazaki-Kariwa 6, the largest unit in the country, returned to service in early 2026. The government estimates that reaching the 2040 target will require up to 30 reactors in operation.
What happened at Fukushima
On 11 March 2011, a magnitude 9.0 earthquake struck off the coast of Tohoku. The operating reactors at Fukushima Daiichi shut down automatically, but the tsunami that followed overwhelmed the seawall and flooded the backup generators and cooling systems. Three reactors suffered meltdowns, and hydrogen explosions destroyed the upper parts of their buildings.
The tsunami killed about 19,000 people. The nuclear accident caused no deaths from acute radiation exposure, but it forced the evacuation of tens of thousands of residents and left a lasting fear of radiation across Japan and abroad. A 2018 lung cancer death of a plant worker was later linked by the Japanese government to radiation exposure, the first such case.
Decommissioning the four damaged units is expected to take decades. Some areas around the plant remain restricted, and the plant's operator has been discharging treated water from the site since August 2023. The International Atomic Energy Agency has monitored the releases and reported that TEPCO's sampling and analysis are accurate and reliable.
Energy situation in Japan
Japan's shortage of minerals and energy shaped its politics and history throughout the 20th century. Today, the country imports more than 80% of its primary energy needs, an unusually high share for a large industrial economy.
When Japan recovered from the damage of World War II and expanded its industrial base, it needed imports of fossil fuels, especially oil from the Middle East. That dependence became critical after the oil shock of 1973. At the time, Japan already had a growing nuclear industry, with five reactors in operation.
The reassessment of domestic energy policy led to diversification and a major nuclear construction program. A high priority was reducing dependence on oil imports. The country also adopted a closed fuel cycle to extract more energy from the uranium it imported.
Government after the Fukushima accident
In July 2011, the Democratic Party of Japan cabinet created the Energy and Environment Council, known as Enecan, to recommend a path for the country's energy future to 2050. Its first review suggested targets of 0%, 15%, or 20-25% for nuclear energy in the medium term.
Public opinion had shifted sharply. The government tried to reduce the role of nuclear power, but the decision cost the Democratic Party of Japan many seats in the 2012 election. The new Liberal Democratic Party government abolished Enecan at the end of 2012 and ordered a review of energy policy from scratch.
In April 2014, the new government adopted the 4th Basic Energy Plan, with a 20-year perspective. It declared nuclear energy a key baseload source that would continue to be used safely to achieve stable and affordable supply and to combat climate change.
In April 2015, the government said it wanted baseload sources to provide 60% of electricity by 2030, with about one-third of that coming from nuclear. The Research Institute of Innovative Technology for the Earth estimated that the plan would cut energy costs by about 2.4 trillion yen, or $20 billion, per year compared with a 40% baseload scenario.
At the same time, 43 coal-fired power projects were planned or under construction, with a combined capacity of 21.2 GW. Coal consumption rose by 20%, and Japan's LNG imports grew from about $20 billion in 2010 to $70 billion in 2013.
Development of the nuclear program
The nuclear research program began in 1954, with a budget of 230 million yen. The Atomic Energy Basic Law, which limits nuclear technology to peaceful purposes, was passed in 1955. The law established three principles: democratic methods, independent management, and transparency.
The inauguration of the Atomic Energy Commission in 1956 helped promote the development and use of nuclear energy. Several other institutions were created under the same law, including the Nuclear Safety Commission and the Japan Atomic Energy Research Institute.
The first reactors
The first reactor to produce electricity in Japan was a prototype boiling water reactor, the Japan Power Demonstration Reactor, which operated from 1963 to 1976 and provided information for later commercial reactors.
Japan imported its first commercial nuclear reactor from the United Kingdom. Tokai 1 was a 160 MWe gas-cooled Magnox reactor built by GEC. It began operating in July 1966 and continued until March 1998.
After Tokai 1, only light water reactors using enriched uranium were built: boiling water reactors and pressurized water reactors. By 1970, the first three of these units were completed and began commercial operation.
Japanese companies soon acquired the ability to build the units themselves. They purchased designs from U.S. vendors and obtained licenses for the later stages. Hitachi, Toshiba and Mitsubishi Heavy Industries developed the capacity to design and build light water reactors on their own.
Improving the light water reactor fleet
As the reactors aged, they fell short in various areas and needed constant upgrades to keep operating. In 1975, the Ministry of International Trade and Industry and the nuclear industry launched the LWR Improvement and Standardization Program.
The program aimed to standardize light water reactor designs in three phases by 1985. Phases 1 and 2 modified existing BWR and PWR designs to improve operation and maintenance. Phase 3 increased reactor size to 1300-1400 MWe and led to the Advanced BWR and the Advanced PWR.
Research centers and the JAEA
The government also established several research centers to support the sector. One of the main centers until the late 1990s was the Power Reactor and Nuclear Fuel Development Corporation, known as PNC. Its activities ranged from uranium exploration in Australia to the disposal of high-level waste.
PNC's reputation suffered after a series of accidents, including the 1995 sodium leak at the Monju prototype fast breeder reactor. The government reconstituted PNC in 1998 as the Japan Nuclear Cycle Development Institute, or JNC, with a focus on fast breeder reactor development, high-burnup fuel reprocessing, and high-level waste disposal.
In 2005, JNC merged with the Japan Atomic Energy Research Institute to create the Japan Atomic Energy Agency, or JAEA. It remains a major integrated nuclear research and development organization.
Monju itself never returned to stable operation. The government confirmed its decommissioning in 2016, citing the cost of meeting the new safety standards.
The restart era
In June 2015, the government approved a plan for electricity generation to 2030, with nuclear at 20-22%, renewables at 22-24%, LNG at 27%, and coal at 26%. The plan aimed to cut CO2 emissions by 21.9% from 2013 levels and raise energy self-sufficiency to 24.3%, up from 6.3% in 2012.
The FY2014 Energy White Paper showed how far the country had moved away from nuclear power. The share of electricity from fossil fuels rose from 62% to 88% in four years. The extra fuel cost caused by the nuclear shutdowns was 2.3 trillion yen in FY2011, 3.1 trillion yen in FY2012, and 3.6 trillion yen in FY2013. Household energy expenses increased by an average of 13.7% over the period.
In July 2017, the cabinet approved the Basic Concept on Nuclear Energy Use, developed over two years with public consultation. The document set eight priority activities for the safe use of nuclear energy. It was revised in February 2023.
The 2021 plan kept the 20-22% nuclear target for 2030 and raised the renewable target to 36-38%, with solar power playing a large part. The 7th Strategic Energy Plan, approved in February 2025, set a nuclear target of around 20% for 2040 and renewables at 40-50%. It also removed the phrase about reducing nuclear dependency as much as possible, which had appeared in previous plans since the Fukushima accident.
In July 2026, ministers responsible for nuclear policy adopted guidelines to replace 2 to 5 reactors by the 2040s and 11 to 14 reactors by the 2050s. The goal is to keep nuclear at about 20% of the electricity mix as older units retire.
The restart process itself has moved slowly. Sendai 1 and Sendai 2 were the first to return, in 2015. Takahama, Ohi, Ikata, Genkai, Mihama, Onagawa and Shimane followed. Onagawa 2 became the first boiling water reactor to restart in October 2024, and Shimane 2 restarted in December of the same year. Kashiwazaki-Kariwa 6, with 1,356 MW, returned in early 2026, giving Japan 15 operating reactors and about 33 GW of nuclear capacity.
Not every application has succeeded. Tsuruga 2 was refused approval in November 2024 because of an active fault under the site. In September 2026, Chubu Electric withdrew its restart applications for Hamaoka 3 and 4 after an independent committee found that earthquake data submitted to the Nuclear Regulation Authority had been manipulated since around 2012. The company's chairman and president resigned.
Natural gas still fills much of the gap. In 2024 it produced 33% of Japan's electricity, while nuclear produced about 9%. The return of Kashiwazaki-Kariwa 6 is expected to displace around 1.3 million tons of LNG imports per year, according to estimates cited by the U.S. Energy Information Administration.
My opinion
I honestly do not think that nuclear power plants are a danger to society. I would criticize much more the countries that use nuclear energy as a way to demonstrate power, such as Russia and the United States, with atomic arsenals built for war.
Japan is not usually negligent when it comes to infrastructure and safety. The country is always developing technologies to meet its needs, whether in commercial, urban, domestic or industrial infrastructure. It seeks improvement, unlike negligent countries that only think about making money.
It also helps to remember that Japan is not rich in natural resources like Brazil. Resources are extremely limited, and so are its plains. For those who do not know, Japan is a predominantly mountainous country, which explains the pressure on space and the need for energy that can be generated at home.
Opinions differ on this subject. Leave yours in the comments and let's see whether we agree or disagree. Before that, remember that the tsunami knocked out the cooling systems at Fukushima Daiichi; the earthquake itself had already shut the reactors down safely. The plant was also vulnerable because of design and regulatory failures, a point the investigations made clear. Still, the size of the wave is what overwhelmed the plant's defenses.
Well, that's all for this article. If you have any questions, suggestions, criticisms, or anything of the sort, just leave your comment. Otherwise, thank you, dear reader, for reading this far, and see you next time.
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