Nuclear power in Japan

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. As of November 2024, 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. 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.

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, Yamaguchi – 1994 The Kushima Nuclear Power Plant at Kushima, Miyazaki – 1997 The Ashihama Nuclear Power Plant at Ashihama, Mie – 2000 (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, Ishikawa – 2003 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.

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