Prior to the March 2011 accident at the Fukushima Daiichi plant, Japan’s 54 reactors provided about 30% of the country’s electricity. However, within 14 months of the accident, the country’s nuclear generation had been brought to a standstill pending regulatory change. Of the 33 units that remain operable, 15 have so far been restarted.
In February 2023, Japan’s Cabinet approved a policy to allow new nuclear power reactors to be constructed and the operation of existing reactors to be extended from 40 to 60 years. “Before 2040, more than 3 million kW of existing reactors will reach 60 years of operation, and after that, the supply capacity of existing reactors as decarbonised power sources will be significantly lost,” the plan said.
The government’s 7th Basic Energy Plan, adopted in February 2025, calls for nuclear electricity generation to increase from 8.5% in fiscal 2023 to about 20% in fiscal 2040. Renewable energy’s share of total electricity production, meanwhile, is expected to increase from 22.9% to 40%-50%, with fossil fuels’ share dropping from almost 69% to 30%-40%.
The Ministry of Economy, Trade and Industry (METI) has now outlined a proposed target to a subgroup of the Advisory Committee for Natural Resources and Energy – which advises the industry minister – for replacing reactors that are scheduled to be decommissioned with new reactors in order to maintain this 20% share.
“Based on certain assumptions, it is estimated that approximately 2.2 to 5.5 million kW (approximately 2 to 5 reactors) of nuclear power plants will need to be replaced by the 2040s, and approximately 12.7 million kW to 16 million kW (approximately 11 to 14 reactors) will need to be replaced by the 2050s, including the work done in the 2040s,” METI said in a . “Furthermore, given that a similar pace of decline in installed capacity is expected from the 2060s onward, and that future electricity demand may increase more than anticipated, in order to ensure a stable supply, efforts under this guideline will be promoted with a view to replacing at least this amount of installed capacity.”
METI said: “It is necessary to present forecasts and a future vision from the perspectives of long-term investment in nuclear power, maintenance of the nuclear industry base, and development and securing of human resources.”
The proposal is expected to be officially approved at a session of relevant Cabinet ministers in the coming months.
