U.S. nuclear power plants operated at an average annual capacity factor of about 91 percent in 2025, far outpacing coal at 48.7 percent and natural gas at 58.4 percent, according to federal generation data. The high capacity factor reflects shorter refueling and maintenance outages and decades of accumulated operational experience.

The fleet remains a large slice of the power mix. Nuclear generation is projected to account for roughly 17 percent of U.S. electricity in 2025, down slightly from 19 percent in 2024, even as total electricity demand rises.

Scale underpins that output. In 2024, U.S. utilities operated 94 commercial reactors with a combined net generating capacity of nearly 97 gigawatts, making the United States the world's largest producer of nuclear electricity.

The performance data help explain the renewed policy interest in extending plant licenses and increasing reactor output. Because nuclear units run near full capacity around the clock, each uprate or restart adds firm, always-on power that utilities are increasingly seeking to balance variable renewable generation and surging data center load.

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