The United States had 96 operating commercial nuclear reactors at 57 nuclear power plants across 28 states as of March 2026, with combined net summer generating capacity of 98,441 megawatts, according to Energy Information Administration figures. The average annual capacity factor for those plants in 2025 was 91%, higher than any other generation type EIA tracks.

The fleet is old and getting older. Average reactor age stands at about 44 years. The oldest unit still running, Nine Mile Point Unit 1 in New York, entered commercial operation in December 1969. The newest, Unit 4 at the Alvin W. Vogtle plant in Georgia, began commercial service in April 2024 and made Vogtle the largest nuclear station in the country.

Reactor counts have declined since 2012, yet total output has held up because operators have pursued uprates that raise the capacity of existing units. Nineteen commercial reactors at 15 sites are in various stages of decommissioning, according to Nuclear Regulatory Commission data cited by EIA.

Site configurations vary. Twenty-two US nuclear plants operate a single reactor, 31 operate two, three operate three, and one operates four. Illinois hosts more reactors than any other state at 11 across six plants, and closed 2025 with the largest state total of net summer capacity at roughly 11,592 megawatts. Grand Gulf Nuclear Station in Port Gibson, Mississippi holds the single largest reactor at about 1,400 megawatts. The two smallest operating units, each near 520 megawatts, sit at Prairie Island in Red Wing, Minnesota.

Source: U.S. Energy Information Administration - https://www.eia.gov/energyexplained/nuclear/us-nuclear-industry.php