Japan started using nuclear power for electricity generation in 1966, and it generated approximately a third of the country's electrical power prior to the Fukushima accident in 2011. After a near-nationwide shutdown following the accident, the share has recovered to 9% in 2025.
The country's nuclear power industry was heavily influenced by the Fukushima accident, caused by the 2011 Tōhoku earthquake and tsunami. After the Fukushima accident, all reactors were shut down temporarily. , of the 54 nuclear reactors present in Japan before 2011, there were 33 operable reactors but only 13 reactors in 6 power plants were actually operating. A total of 24 reactors are scheduled for decommissioning or are in the process of being decommissioned. Others are in the process of being reactivated, or are undergoing modifications aimed at improving resiliency against natural disasters; Japan's 2030 energy goals posit that at least 33 will be reactivated by a later date.
The Fukushima accident hardened attitudes toward nuclear power. In June 2011, immediately after the accident, more than 80% of Japanese said they were anti-nuclear and distrusted government information on radiation, but ten years later, in March 2021, only 11 percent of Japanese said they wanted that nuclear energy generation to be discontinued immediately. Another 49 percent were asking for a gradual exit from nuclear energy. In February 2023, a survey by Asahi Shimbun showed that 51% of participants in Japan favored the restart of nuclear plant operations, with 42% opposed.
History Early years
Japan's nuclear development began in the 1930s with the Japanese nuclear weapons program. After the war, the United States imposed a total ban on nuclear research during the post-war occupation of Japan.
Following the December 1953 Atoms for Peace speech at the UN General Assembly by U.S. President Eisenhower, future Prime Minister Yasuhiro Nakasone and his peers from the Kaishintō Party (a forerunner to the Liberal Democratic Party) drafted a 235-million-yen budget (the amount symbolically referencing uranium-235). Members of the National Diet took part in the 1955 Geneva Conference on the Peaceful Uses of Atomic Energy and drafted legislation governing Japan's nuclear program.
Around the same time, the Atomic Energy Act of 1954 was enacted in America, and Japan received condensed uranium from the country in 1955. Two experimental reactors, JRR-1 (built by North American Aviation's nuclear division) and JRR-2 (largely based on Chicago Pile-5), were constructed. A much more powerful experimental reactor JRR-3 was completed in 1962 by a consortium led by Hitachi, the first experimental reactor to be fully designed and built in Japan. Also in 1955, Nakasone's group drafted the Atomic Energy Basic Law, which was enacted in Japan to promote nuclear power while limiting activities strictly to peaceful purposes.Johnston, Eric, "Key players got nuclear ball rolling ", Japan Times, 16 July 2011, p. 3. The Japanese Atomic Energy Commission was established as a regulatory body, with its first chair, Matsutarō Shōriki, a newspaper magnate, also being a key promoter of nuclear power in Japan.
A prototype nuclear power station, JPDR, began power generation on 26 October 1963. Japan's first commercial nuclear power plant, the Tōkai Nuclear Power Plant, was built using main components imported from the General Electric Company in the UK and was connected to the grid on 25 July 1966. This reactor remains the only Magnox reactor ever built on Japanese soil. In 1969, the first nuclear-powered ship in Japan (and the fourth in the world), Mutsu, was launched by Mitsubishi Heavy Industries (reactor) and IHI (hull).
Light water reactors
General Electric offered light water reactors at a discounted price as soon as Yasuhiro Nakasone, then the Minister of Science and Technology, began revising the country's nuclear power strategy in 1961. This offer was accepted, and Tsuruga-1 was commissioned in March 1970 as Japan's first BWR. GE teamed up with Hitachi and Toshiba to build BWRs, while Westinghouse collaborated with Mitsubishi Heavy Industries (MHI) to promote PWRs. By the late 1970s, these companies began constructing plants independently. All nuclear reactors built in Japan have been either BWRs or PWRs, with Hitachi and Toshiba (which later acquired Westinghouse's nuclear division to build PWRs as well) still responsible for the former and MHI for the latter.
Developments in nuclear power since that time have seen contributions from Japanese companies and research institutes on the same level as the other major users of nuclear power. From the early 1970s to the present, the Japanese government promoted the siting of nuclear power plants through a variety of policy instruments involving soft social control and financial incentives.Daniel P. Aldrich 'How the Japanese Government Manipulated Public Opinion'
Later years
Japan's nuclear industry was not hit as hard by the effects of the Three Mile Island accident (TMI) or the Chernobyl disaster as some other countries. Construction of new plants remained strong throughout the 1980s and 1990s. While many new plants had been proposed, all were subsequently canceled or never brought past initial planning. Cancelled plant orders include: The Hōhoku Nuclear Power Plant at Hōhoku, Yamaguchi1994 The Kushima Nuclear Power Plant at Kushima, Miyazaki1997 The Ashihama Nuclear Power Plant at Ashihama, Mie2000 (the first Project at the site in the 1970s was completed at Hamaoka as Unit 1&2) The Maki Nuclear Power Plant at Maki, Niigata (Kambara)Canceled in 2003 The Suzu Nuclear Power Plant at Suzu, Ishikawa2003
Starting in the mid-1990s, there were several nuclear-related accidents and cover-ups in Japan that eroded public perception of the industry, resulting in protests and resistance to new plants. These accidents included the Tokaimura nuclear accident, the Mihama steam explosion, cover-ups after an accident at the Monju reactor, among others, more recently the Chūetsu offshore earthquake aftermath. While exact details may be in dispute, it is clear that the safety culture in Japan's nuclear industry has come under greater scrutiny. [The news fails to note that the Tokaimura accident did not happen in a power plant.]
2000s On 18 April 2007, Japan and the United States signed the United States-Japan Joint Nuclear Energy Action Plan, aimed at putting in place a framework for the joint research and development of nuclear energy technology.United States and Japan Sign Joint Nuclear Energy Action Plan , United States Department of Energy, published 2007-04-25, accessed 2 May 2007 Each country will conduct research into fast reactor technology, fuel cycle technology, advanced computer simulation and modeling, small and medium reactors, safeguards and physical protection; and nuclear waste management.Fact Sheet: United States-Japan Joint Nuclear Energy Action Plan , United States Department of Energy, published 2007-04-25, accessed 2 May 2007 In March 2008, Tokyo Electric Power Company announced that the start of operation of four new nuclear power reactors would be postponed by one year due to the incorporation of new earthquake resistance assessments. Units 7 and 8 of the Fukushima Daiichi plant would now enter commercial operation in October 2014 and October 2015, respectively. Unit 1 of the Higashidori plant is now scheduled to begin operating in December 2015, while unit 2 will start up in 2018 at the earliest. As of September 2008, Japanese ministries and agencies were seeking an increase in the 2009 budget by 6%. The total requested comes to 491.4 billion Japanese yen (US$4.6 billion), and the focuses of research are the development of the fast breeder reactor cycle, next-generation light water reactors, the Iter project, and seismic safety.NucNet. Japan Budget Proposals Seek Increase In Nuclear Spending . 11 September 2008.
Fukushima accident and aftermath
An energy white paper, approved by the Japanese Cabinet in October 2011, says "public confidence in the safety of nuclear power was greatly damaged" by the Fukushima accident in March 2011, and calls for a reduction in the nation's reliance on nuclear power. It also omits a section on nuclear power expansion that was in the previous year's policy review. Nuclear Safety Commission Chairman Haruki Madarame told a parliamentary inquiry in February 2012 that "Japan's atomic safety rules are inferior to global standards and left the country unprepared for the Fukushima nuclear disaster last March". There were flaws in, and lax enforcement of, the safety rules governing Japanese nuclear power companies, and this included insufficient protection against tsunamis.
On 6 May 2011, Prime Minister Naoto Kan ordered the Hamaoka Nuclear Power Plant to be shut down as an earthquake of magnitude 8.0 or higher is likely to hit the area within the next thirty years.Story at BBC News, 6 May 2011. retrieved 8 May 2011Story at Digital Journal. retrieved 7 May 2011Story at Bloomberg , 7 May 2011. retrieved 8 May 2011
As of 27 March 2012, Japan had only one out of 54 nuclear reactors operating; the Tomari-3, after the Kashiwazaki-Kariwa 6 was shut down."Soon Japan's nuclear power stands still" NyTeknik, 27 March 2012. Retrieved 27 March 2012. English translation The Tomari-3 was shut down for maintenance on 5 May, leaving Japan with no nuclear-derived electricity for the first time since 1970, when the country's then-only two reactors were taken offline for five days for maintenance. On 15 June 2012, approval was given to restart Ōi Units 3 and 4Real-time display Japanese – Ohi 3 and 4 are the last two on the page which could take six weeks to bring them to full operation. On 1 July 2012, unit 3 of the Ōi Nuclear Power Plant was restarted. This reactor can provide 1,180 MW of electricity. On 21 July 2012 unit 4 was restarted, also 1,180 MW. The reactor was shut down again on 14 September 2013, again leaving Japan with no operating power reactors.Matsuyama, Kanoko. "Shutdown of Japan’s Last Nuclear Reactor Raises Power Concerns". Bloomberg. 15 September 2013. Retrieved 5 February 2014.
Government figures in the 2014 Annual Report on Energy show that Japan depended on imported fossil fuels for 88% of its electricity in fiscal year 2013, compared with 62% in fiscal 2010. Without significant nuclear power, the country was self-sufficient for just 6% of its energy demand in 2012, compared with 20% in 2010. The additional fuel costs to compensate for its nuclear reactors being idled was ¥3.6 trillion. In parallel, domestic energy users have seen a 19.4% increase in their energy bills between 2010 and 2013, while industrial users have seen their costs rise 28.4% over the same period.
In 2018 the Japanese government revised its energy plan to update the 2030 target for nuclear energy to 20%-22% of power generation by restarting reactors, compared to LNG 27%, coal 25%, renewables 23% and oil 3%. This would reduce Japan's carbon dioxide emissions by 26% compared to 2013, and increase self-sufficiency to about 24% by 2030, compared to 8% in 2016.
Since the Fukushima nuclear accident, Japan has restarted twelve reactors and fifteen more have applied to restart, including two that are under construction. Amid the Russian invasion of Ukraine, Japan's Prime Minister announced the restart of nine units by winter 2022 and seven more by summer 2023.
Investigations on the Fukushima accident
The National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) is the first independent investigation commission by the National Diet in the 66-year history of Japan's constitutional government. NAICC was established on 8 December 2011 with the mission to investigate the direct and indirect causes of the Fukushima nuclear accident. NAICC submitted its inquiry report to both houses on 5 July 2012.