Japanese utilities restarted two additional nuclear reactors in 2024 that had been suspended from operations in response to the 2011 Fukushima Daiichi accident, taking the total number of restarted reactors to 14 since the accident. In November, Tohoku Electric Power Co. restarted its 796-megawatt (MW) Onagawa Unit 2 reactor, and in December Chugoku Electric Power Co. restarted its Shimane Unit 2 (789 MW). Onagawa is the nuclear power plant located closest to the epicenter of the March 2011 earthquake and tsunami.
Most of the restarted reactors have been pressurized water reactors (PWR) located in western Japan. Onagawa Unit 2 and Shimane Unit 2, by contrast, are the first boiling water reactors (BWR) to be restarted. Onagawa Unit 2 is also the first reactor in the eastern part of the country to be restarted. Japan’s nuclear regulator prioritized the restart of PWRs due to public safety concerns regarding BWR technology, which is the design of the Fukushima Daiichi units.
Japan suspended its nuclear fleet from 2013 to 2015 for mandatory safety checks and upgrades following the 2011 Fukushima Daiichi accident. Before the accident, 54 commercial nuclear reactors were operating in Japan, and nuclear power accounted for approximately 30% of the country’s electricity generation. Nuclear restarts have proceeded slowly since the first two units (Sendai Units 1 and 2) were restarted in 2015. Restarts have been slow due to a significantly more stringent safety inspection and authorization process established after the accident and local court injunctions emerging from ongoing public safety concerns in some regions. Public support for restarts has been growing in Japan recently, however.
Under the current restart process, once regulatory approvals have been granted, the local municipality and prefectural governments are consulted prior to restart. In addition to the 14 reactors already restarted, three more units (namely, the Kashiwazaki-Kariwa Unit 6 and Unit 7 and the Tokai Daini unit) have received regulatory approval to restart but have yet to do so. Tohoku Electric Power announced in 2018 that Onagawa Unit 1 would be decommissioned rather than upgraded, but the utility plans to seek approval to restart Onagawa Unit 3. Restarting another 10 units is under regulatory review.
Note: PWR=pressurized water reactor. BWR=boiling water reactor
The suspension of Japan’s nuclear fleet after the Fukushima accident significantly increased dependence on natural gas, oil, and coal imports to make up for lost domestic nuclear generation. It also significantly increased the installed capacity of solar photovoltaic generation in the country, according to data from Japan’s Ministry of Economy, Trade and Industry. Japan has limited domestic fossil fuel resources and imports virtually all the fossil fuels it uses. Consequently, Japan is the world’s second-largest importer of liquefied natural gas (LNG) after China and the third-largest importer of coal.
As part of Japan’s sixth long-term energy plan, last updated in October 2021, the central government called for the nuclear share of the country’s electricity generation to reach 20%–22% by 2030. Nuclear power accounted for about 6% of Japan’s electricity generation in 2023. A draft of Japan’s seventh long-term energy plan was released on December 17, 2024, and says nuclear power should account for 20% of Japan’s energy supply in 2040.
Japan’s current policy intends to maximize the use of existing reactors by restarting as many units as possible and extending the licensed operating life beyond the current 60-year limit. The country also plans to develop next-generation reactors in cooperation with the domestic manufacturing industry and electric utilities.
More information about energy trends in Japan is available on EIA’s international analysis webpage.
Source: U.S. E.I.A.
