The US nuclear fleet continues to deliver a large and highly reliable share of the country's electricity, according to generating statistics from the Nuclear Energy Institute and the Energy Information Administration. As of March 2026, the United States operated 96 commercial nuclear reactors at 57 plants across 28 states, with combined net summer generating capacity of 98,441 megawatts.

Reliability sets nuclear apart from other sources. The fleet posted an average annual capacity factor of 91 percent in 2025, higher than any other type of power plant. Capacity factor measures how much electricity a plant produces relative to its maximum possible output, and the 91 percent figure reflects reactors that run near continuously with only brief interruptions for refueling and maintenance.

The fleet has aged while holding its output. The average reactor is about 44 years old, and although the total number of reactors has declined since 2012, capacity uprates at individual plants have allowed the overall fleet to maintain high utilization. Those modifications increase the power a reactor can produce, offsetting the loss of retired units and keeping total generation roughly stable.

Nuclear supplies close to 18 percent of US electricity, a share it has held steady in recent years. Because reactors run regardless of weather or time of day, they provide baseload power that complements variable sources on the grid. The statistics describe a mature fleet that, despite its age and a smaller reactor count than a decade ago, remains one of the most productive and consistent components of the national power system.

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