Five Countries Hold 71 Per Cent of the World's Nuclear Capacity. The Next Decade Will Be Decided by Two of Them

Nuclear power is often discussed as a global technology, but its geography is remarkably concentrated. According to US Energy Information Administration analysis of International Atomic Energy Agency data as of June 2025, there are 416 operating power reactors in 31 countries, with a combined net capacity of 376 gigawatts. Five countries, the United States, France, China, Russia and South Korea, account for 71 per cent of that capacity. Most large fleets were built in a burst of construction between the late 1960s and 1990, often in direct response to the oil shocks of the 1970s.

Utilities operate 94 reactors, most built between 1967 and 1990, and nuclear supplied 19 per cent of US electricity in 2024. France is the second-largest fleet and the largest in Europe, with 57 reactors and 63 gigawatts of capacity. Its story is the clearest example of nuclear as an energy security policy: 52 reactors were built between 1975 and 1990 after the oil crisis. France also shows how operational recovery can matter as much as new build.

French cross-border electricity deliveries rose 48 per cent, from 70 terawatt-hours in 2023 to 103 terawatt-hours in 2024, according to the EIA's reading of ENTSO-E data. It has commissioned 57 reactors since 1991, and according to IAEA data cited by the EIA, another 28 reactors with a combined 30 gigawatts are under construction. China has also built a domestic supply chain by absorbing foreign technology. It acquired reactor designs from France, Canada and Russia, and has adapted the Westinghouse AP1000 into its own CAP1000.

Russia operates 36 reactors with 27 gigawatts of capacity and has 4 more units, about 4 gigawatts, under construction. South Korea's programme, started in the 1970s, is driven by energy security and a desire to limit dependence on imported fuels. Japan sits outside the top five but remains a large nuclear country in suspended form. The construction burst of 1967 to 1990 has a consequence that is easy to overlook. Third, for the incumbent fleets in the United States and France, the most valuable nuclear capacity over the next decade is the capacity that already exists.