A close look at reactor-level generation data compiled by the Nuclear Energy Institute shows the scale of the US commercial nuclear fleet's output: 96,531 megawatts of net summer capacity spread across more than 90 reactors nationwide, generating a combined 778 million megawatt-hours in a single year, according to figures reported to the US Energy Information Administration. The fleet-wide average capacity factor, the share of maximum possible output a plant actually achieves over time, reached 92.7 percent, a figure many individual units exceeded. Nine Mile Point 2 in New York posted a capacity factor above 111 percent for the year measured, reflecting a power uprate that pushed the plant beyond its original rated output, while Prairie Island 1 in Minnesota and Calvert Cliffs 1 in Maryland both topped 103 percent.
Georgia's two Vogtle units and two Hatch units contributed a combined output in the tens of millions of megawatt-hours, part of a fleet that spans pressurized water and boiling water reactor designs across dozens of states. The data also shows a wide range in performance across the fleet: while dozens of units cleared 95 percent, a handful, including Callaway in Missouri and Diablo Canyon 2 in California, posted capacity factors well below 70 percent that year, a range typically associated with extended refueling or maintenance outages. NEI compiles the reactor-by-reactor figures from EIA reporting to give utilities, regulators and investors a standardized view of how consistently the fleet converts fuel into electricity, a metric the industry uses to argue that nuclear plants outperform most other generation sources on reliability.
Source: Nuclear Energy Institute - https://www.nei.org/resources/statistics/us-nuclear-operating-plant-basic-information