US nuclear plants generated 775.4 million megawatt hours of electricity in 2023, supplying 18.2 percent of the nation's total electricity output, according to statistics compiled by the Nuclear Energy Institute using US Energy Information Administration data. The fleet's capacity factor, a measure of how much of a plant's maximum possible output it actually generates, stood at 93.0 percent for the year, extending a run of capacity factors above 90 percent that stretches back more than two decades.

Total US nuclear summer capacity stood at 95,773 megawatts in 2023, spread across the operating reactor fleet. The nuclear fuel share of total US electricity generation has held in a narrow band between about 18 and 20 percent since the late 1990s, even as total US electricity generation has grown substantially over the same period.

The consistency of nuclear output stands out against more variable generation sources. Capacity factor has climbed steadily since the 1970s, when plants often ran below 60 percent of rated output, reflecting decades of operational improvements, longer refueling cycles, and fewer unplanned outages across the fleet.

Utilities and policymakers have pointed to this reliability record as a reason to extend the operating life of existing reactors and pursue new nuclear construction to meet rising electricity demand from data centers and manufacturing.

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