Operable nuclear power reactors worldwide 2025, by country

As of May 2025, there were 439 nuclear reactors in operation in over 30 countries around the world. The United States had the largest number of nuclear power reactors in operation at the time, at 94 units. Operable nuclear reactors refer to those that are connected to the grid. 

Nuclear reactors under construction

The largest reactors under construction as of July 2024 were situated in the United Kingdom, with a gross electricity generation capacity of 1,720 megawatts. Meanwhile, the country with the largest capacity of nuclear reactors under construction worldwide was China, where reactors with a total capacity of almost 30 gigawatts were being built at the time.

Uranium supply worldwide

Uranium is a radioactive metal that is extracted from mines, mainly in Kazakhstan, Australia, and Namibia. After the uranium splitting process for nuclear fission, the used fuel elements are still radioactive and have to be stored in nuclear waste repositories or spent fuel pools. These sites are often underground and require thick metal or concrete walls to shield the public from radiation.