US nuclear power plants generated 775.4 million megawatt-hours of electricity in 2023, representing 18.2 percent of total US electricity generation that year, according to the Nuclear Energy Institute's long-running generating statistics series, which draws on data from the US Energy Information Administration. The fleet posted a capacity factor of 93 percent, meaning reactors produced electricity at 93 percent of their theoretical maximum output across the year, a figure that consistently ranks among the highest of any electricity source in the country.
The industry's capacity factor has climbed steadily since the early 1990s. NEI's data shows the fleet averaged just 56 percent in 1980, rose above 70 percent by the early 1990s, and has held above 90 percent every year since 2001, reflecting decades of operational improvements, more efficient refueling outages, and fewer unplanned shutdowns across the industry.
As of March 2026, the United States operates 96 commercial nuclear reactors across 57 power plants in 28 states, with combined net summer generating capacity of roughly 98,441 megawatts, according to federal data. Nuclear power is projected to supply approximately 18 percent of total US electricity generation in 2026, holding roughly steady with the prior year's share even as overall electricity demand climbs.
The average age of the operating US reactor fleet is approximately 44 years, with many plants having received license renewals extending their operating lives well beyond their original 40-year design term. Industry and federal officials have pointed to that combination of high reliability and long operating life as a central reason utilities and large corporate electricity buyers have increasingly sought long-term nuclear power purchase agreements to meet growing demand from data centers and other large loads.
Source: Nuclear Energy Institute – https://www.nei.org/resources/statistics/us-nuclear-generating-statistics