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 June 2022, 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
|March 2011||Great East Japan Earthquake and TEPCO Fukushima Daiichi Nuclear Power Station accident.|
|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.|
|June 2012||The operating period of nuclear power plants is limited to 40 years in principle.|
|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).|
|September 2012||Nuclear Regulation Authority established.|
|July 2013||New regulatory standards relating to natural disasters and terrorist attacks introduced for nuclear power plants.|
|September 2013||No. 3 and No. 4 reactors at Ōi Nuclear Power Plant undergo regular inspection and nuclear power generation drops back to zero.|
|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.|
|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.|
|January/February 2016||No. 3 and No. 4 reactors at Takahama Nuclear Power Plant (Kansai Electric Power Company) resume operation.|
|August 2016||No. 3 reactor at Ikata Nuclear Power Plant (Shikoku Electric Power Company) resumes operation.|
|March/May 2018||No. 3 and No. 4 reactors at Ōi Nuclear Power Plant resume operation.|
|March/June 2018||No. 3 and No. 4 reactors at Genkai Nuclear Power Plant (Kyūshū Electric Power Company) resume operation.|
|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.|
|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.|
|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).|
|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.|
|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.|
|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.|
|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||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 station beyond its 40-year lifespan.|
|June 2021||Mihama Nuclear Power Station (Kansai Electric Power Company) restarts operation for the first time since being shut down for routine inspection a decade before (operations are halted in October of the same year for failure to implement antiterrorism measures by the deadline).|
|May 2022||The Nuclear Regulation Authority approves a draft review report that finds appropriate TEPCO’s plan to install facilities necessary for the offshore discharge of treated water containing radioactive tritium generated at the Fukushima Daiichi Nuclear Power Plant. The plan involves diluting the water with seawater to reduce the tritium concentration to less than 1/40 of the legal standard and discharge it about 1 kilometer offshore through a newly constructed undersea tunnel.|
|June 2022||Shimane Prefecture Governor Maruyama Tatsuya approves the restarting of the Shimane Nuclear Power Station (Chūgoku Electric Power Company).|
(Translated from Japanese. Banner photo: Shimane Nuclear Power Station, operated by Chūgoku Electric Power Company. © Pixta.)