New data compiled by the Nuclear Energy Institute shows the nuclear fleet's performance holding remarkably steady even as output volumes have leveled off. In 2023, the most recent full year reflected in NEI's dataset, US reactors generated 775.4 million megawatt-hours of electricity, supplying 18.2 percent of the nation's total electricity generation.
The figures show the fleet's capacity factor, a measure of how much of a plant's maximum potential output was actually generated, reached 93.0 percent in 2023. That figure has climbed steadily since the 1990s, when capacity factors typically ran in the 65 to 75 percent range, reflecting shorter refueling outages and more consistent plant operations across the industry.
Total summer capacity across the US reactor fleet stood at 95,773 megawatts in 2023, down slightly from a peak above 100,000 megawatts in the mid-2000s as several older plants retired, including Indian Point, Palisades, and Three Mile Island Unit 1. Despite the retirements, output per remaining reactor has risen as utilities have pushed capacity factors higher.
NEI compiles the data from US Energy Information Administration figures and updates the dataset periodically as new generation numbers become available.
Source: Nuclear Energy Institute - https://www.nei.org/resources/statistics/us-nuclear-generating-statistics