Japan’s Nuclear Power Plants in 2023
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On July 28, 2023, Kansai Electric Power restarted the No. 1 reactor at Takahama Nuclear Power Plant in Fukui Prefecture, which is the oldest in Japan, having started operations more than 48 years ago. It had been inactive since it was shut down 12 years ago for regular inspection in January 2011, prior to the Great East Japan Earthquake. This is now the second nuclear reactor over 40 years old to have resumed operations, following the No. 3 reactor at the Mihama plant, also located in Fukui. The No. 2 reactor at Takahama, which has been in operation for 47 years, is also set to restart from mid-September.
In May 2023, the Japanese government enacted a bill to promote green transformation. This allows a relaxation in the current regulation of the operating period for nuclear plants being “40 years in principle and a maximum of 60 years,” which had been set following the March 2011 TEPCO Fukushima Daiichi nuclear power plant accident, and, because periods of suspension including for safety inspections are not counted, it means that plants can effectively stay in operation for more than 60 years. As the government faces difficulties building new nuclear power plants, the decision was made to switch to extending the life of existing plants in order to ensure a stable supply of electricity and aim toward achieving carbon neutrality.
Prior to the Great East Japan Earthquake of 2011, 54 nuclear reactors were in operation in Japan, supplying approximately 30% of the country’s electric power. However, the disaster at the Fukushima Daiichi Nuclear Power Plant was a drastic blow to nuclear power’s reputation, leading to increased distrust and unease toward the energy source.
As of August 2023, only 10 reactors have been restarted with local approval at the following six power stations: Ōi, Takahama, and Mihama (Kansai Electric Power Company), Genkai and Sendai (Kyūshū Electric Power Company), and Ikata (Shikoku Electric Power Company). These plants based in western Japan all use pressurized water reactors, which are different from the boiling water reactors at the Fukushima Daiichi Nuclear Power Plant.
Boiling water reactors at the Onagawa (Tōhoku Electric Power Company), Kashiwazaki-Kariwa (Tokyo Electric Power Company), Tōkai Daini (Japan Atomic Power Company), and Shimane (Chūgoku Electric Power Company) nuclear power stations have all been approved under the new regulatory standards, but none have received the green light to restart.
In total, 21 nuclear reactors have been decommissioned since the 2011 Great East Japan Earthquake.
Nuclear Power Plants: Major Developments Since the Great East Japan Earthquake
| September 2023 | No. 2 reactor at Takahama Nuclear Power Plant (Kansai Electric Power Company), which first started operating 47 years ago, is set to restart. |
| Summer 2023 | Scheduled start of release of treated water containing radioactive tritium that has accumulated at the No. 1 reactor of Fukushima Daiichi Nuclear Power Plant. |
| July 2023 | No. 1 reactor at Takahama Nuclear Power Plant, which first started operating 48 years ago, resumes operation after a 12-year hiatus. |
| July 2023 | The International Atomic Energy Agency publishes a comprehensive report concluding that the planned release of treated water into the sea from TEPCO’s Fukushima Daiichi nuclear power plant is “consistent with international safety standards.” |
| May 2023 | The GX Decarbonization Power Supply bill is enacted. In order to ensure stable power supply and achieve decarbonization, significant changes are made to the safety regulations stipulating that the operating period for reactors is “40 years in principle and a maximum of 60 years,” making it possible for them to operate for periods of longer than 60 years. |
| June 2022 | Shimane Prefecture Governor Maruyama Tatsuya approves the restarting of the Shimane Nuclear Power Plant (Chūgoku Electric Power Company). |
| June 2021 | Mihama Nuclear Power Plant (Kansai Electric Power Company) restarts operation for the first time since being shut down for routine inspection a decade before. At 44 years since it began operation, it is the first nuclear plant to restart despite being more than 40 years old. |
| April 2021 | Fukui Governor Sugimoto Tatsuji announces his approval for restarting the Mihama Reactor 3 and Takahama Reactors 1 and 2, which have all been operated by Kyūshū Electric Power Company for over 40 years. This is the first time since the accident at the Fukushima Daiichi Nuclear Power Plant for local authorities to approve the restart of a nuclear power plant beyond its 40-year lifespan. |
| April 2021 | The Nuclear Regulatory Commission officially decides to issue a corrective action order prohibiting the movement of nuclear fuel within the Kashiwazaki-Kariwa Nuclear Power Plant until additional inspections confirm that issues have been resolved. Preparations to restart reactors are halted. |
| April 2021 | The government decides to dilute the water containing tritium that continues to accumulate at the Fukushima Daiichi Nuclear Power Plant before discharging the treated water into the ocean. |
| March 2021 | The Nuclear Regulation Authority announces that the intruder detection system at Kashiwazaki-Kariwa Nuclear Power Plant had not been functioning since March 2020 and that adequate alternative measures were not taken. |
| January 2021 | It is discovered that there was unauthorized use of an employee ID card to enter the central control room at Kashiwazaki-Kariwa nuclear power plant (TEPCO) in September 2020. |
| December 2020 | Osaka District Court rules to cancel permission to resume operation of No. 3 and No. 4 reactors at Ōi Nuclear Power Plant (the Japanese government appeals). |
| November 2020 | Miyagi Governor Murai Yoshihiro gives approval for Onagawa Nuclear Power Plant (Tōhoku Electric Power Company) to resume operation. This is the first approval for a boiling water reactor, the same type as at the Fukushima Daiichi plant where the accident occurred. Tōhoku Electric Power Company aims to start operation after fiscal 2020. |
| July 2018 | The cabinet approves the fifth energy basic plan with the intention to have nuclear power account for 20-22% of power generation in 2030. |
| March/June 2018 | No. 3 and No. 4 reactors at Genkai Nuclear Power Plant (Kyūshū Electric Power Company) resume operation. |
| March/May 2018 | No. 3 and No. 4 reactors at Ōi Nuclear Power Plant resume operation. |
| August 2016 | No. 3 reactor at Ikata Nuclear Power Plant (Shikoku Electric Power Company) resumes operation. |
| January/February 2016 | No. 3 and No. 4 reactors at Takahama Nuclear Power Plant (Kansai Electric Power Company) resume operation. |
| August/October 2015 | No. 1 and No. 2 reactors at Sendai Nuclear Power Plant (Kyūshū Electric Power Company) resume operation. These are the first restarts since the introduction of the new standards and follow almost two years without nuclear power. |
| April 2014 | The cabinet approves the fourth energy basic plan, positioning nuclear power plants as an important base-load power source, while also pledging to reduce dependency on nuclear power as much as possible by introducing renewable energy. |
| September 2013 | No. 3 and No. 4 reactors at Ōi Nuclear Power Plant undergo regular inspection and nuclear power generation drops back to zero. |
| July 2013 | New regulatory standards relating to natural disasters and terrorist attacks introduced for nuclear power plants. |
| September 2012 | Nuclear Regulation Authority established. |
| July 2012 | No. 3 and No. 4 reactors at Ōi Nuclear Power Plant (Kansai Electric Power Company) resume operation (ending a 2-month period of no nuclear power generation in Japan). |
| June 2012 | The operating period of nuclear power plants is limited to 40 years in principle. |
| May 2012 | Tomari Nuclear Power Plant (Hokkaidō Electric Power Company) suspends operation of its No. 3 reactor and for the first time in 42 years there are no nuclear power plants operating within Japan. |
| March 2011 | Great East Japan Earthquake and TEPCO Fukushima Daiichi Nuclear Power Plant accident take place. |
(Translated from Japanese. Banner photo: Takahama Nuclear Power Plant, operated by Kansai Electric Power Company. The No. 1 reactor is in the foreground at right with No.2 behind it. The No.3 reactor is at the far left with No. 4 behind it. © Jiji.)