Japan - World Nuclear Outlook Report

Projection of future nuclear capacity in Japan in 2050

Japan depends on imports for approximately 90% of its primary energy demand. Released in 2010 – before the accident at the Fukushima Daiichi nuclear plant in March 2011 – Japan’s third energy plan positioned nuclear energy to have

a key role in energy security and the low-carbon transition, proposing to build more than 14 reactors and increase the proportion of zero-emissions energy (nuclear and renewables) in the electricity mix to 70% by 2030.¹²²

Nuclear plans were scaled back following the Fukushima Daiichi accident. However, in its sixth Strategic Energy Plan published in 2021, and The Basic Policy for the Realization of GX (green transformation) in 2023, the government was more positive on extending operation at existing plants, as well as building new reactors.^123,124 That policy set a target of having 20-22% of electricity being supplied by nuclear by 2030, requiring a total nuclear capacity of around 27 GWe.¹²⁵ In February 2025 the government’s Seventh Strategic Energy Plan set a target of nuclear to supply around 20% of electricity in 2040.¹²⁶

In its Green Growth Strategy in line with Carbon Neutrality in 2050 published in December 2020, the government said it aimed for approximately 30-40% of power generation in 2050 to be covered by both nuclear power and thermal power generation with carbon dioxide capture. In addition, electricity demand was estimated to increase by about 30-40% due to electrification.¹²⁷

Japan had 55 operable nuclear reactors at the time of the March 2011 accident at Fukushima, all of which were taken offline when the accident occurred or in the months after. Up to October 2025, 14 units have restarted, with 19 operable units still requiring permission to restart, of which 11 units have applied to restart.¹²⁸

Construction on two reactors, Shimane 3 and Ohma, was suspended following the Fukushima Daiichi accident. Their operating companies are seeking regulatory approval to restart construction.

Long-term operation

In May 2023 parliament approved a new rule allowing reactors to operate beyond 60 years by excluding those years when reactors were offline following the Fukushima Daiichi accident.¹²⁹ Other than this exception, nuclear plant operating lifetimes in Japan are limited to 60 years.