The latest figures from the US Energy Information Administration provide a detailed snapshot of the American nuclear fleet. As of March 2026, the United States had 96 operating commercial nuclear reactors at 57 power plants spread across 28 states, with a combined net summer generating capacity of 98,441 megawatts.

The fleet's age profile underscores the durability of the technology. The average US reactor is about 44 years old. The oldest operating unit, Nine Mile Point Unit 1 in New York, began commercial service in December 1969, while the newest, Unit 4 at the Alvin W. Vogtle Electric Generating Plant in Georgia, entered commercial operation in April 2024.

Although the number of reactors has declined since 2012, EIA notes that power uprates, which are modifications that increase a unit's output, have allowed the operating fleet to maintain high capacity-utilization rates. Those sustained capacity factors are a key reason nuclear plants continue to produce a large share of US electricity from a comparatively small number of facilities.

On the other end of the lifecycle, the Nuclear Regulatory Commission reports that 19 commercial power reactors at 15 sites are in various stages of decommissioning after retirement from commercial service.

Commercial nuclear generation in the United States dates to 1958, when the Shippingport plant in Pennsylvania came online, an outgrowth of the first controlled nuclear chain reaction achieved at the University of Chicago in 1942.

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