The United States operated 96 commercial nuclear reactors at 57 plants across 28 states as of March 2026, according to industry statistics. The combined net summer generation capacity of the fleet stood at 98,441 megawatts, making nuclear one of the largest sources of always-on electricity in the country.

Reliability sets nuclear apart. The average annual capacity factor for US nuclear plants in 2025 was 91 percent, higher than any other generation type. That figure measures how much electricity plants actually produce against their maximum possible output, and the fleet consistently ranks at the top on this metric despite its age.

The fleet is mature. The average reactor is about 44 years old, a fact that has made license renewals central to keeping capacity online. The newest unit is Vogtle Unit 4 in Georgia, which entered commercial operation in April 2024 as the most recent reactor added in the country.

Capacity is concentrated in a handful of states. Illinois hosts more reactors than any other state, with 11 units at 6 plants, and closed 2025 with the largest total nuclear capacity at roughly 11,592 megawatts. The distribution reflects decades-old siting decisions that continue to shape which regions lean most heavily on nuclear power. With demand climbing, operators are pursuing renewals and uprates to preserve every megawatt of the existing base.

Source: Nuclear Energy Institute - https://www.nei.org/resources/statistics/us-nuclear-generating-statistics