As of December 31, 2021, there were 93 operating nuclear reactors at 55 nuclear power plants in the United States. The R.E. Ginna Nuclear Power Plant in New York is the smallest nuclear power plant in the United States, and it has one reactor with a net summer electricity generating capacity of about 582 megawatts (MW). The Prairie Island nuclear plant in Minnesota has two reactors, each with about 520 MW net summer generating capacity (the smallest reactors operating in the United States) for a total plant capacity of 1,040 MW. The Palo Verde nuclear power plant in Arizona is the largest nuclear power plant in the United States with three reactors and a total net summer electricity generating capacity of about 3,937 MW.
The amount of electricity that a power plant generates during a period of time depends on the amount of time its reactors operate at a specific capacity. For example, if the R.E. Ginna reactor operates at 582 MW capacity for 24 hours, it will generate 13,968 megawatthours (MWh). If the reactor generated that amount of electricity for 365 days, it would generate 5,098,320 MWh. However, most power plants do not operate at full capacity every hour of every day of the year. In 2021, the R.E. Ginna nuclear power plant actually generated a total of 4,727,764 MWh, achieving an annual average capacity factor of about 93%.
Nuclear power reactors generally operate at or near their rated generating capacity throughout the year and have relatively high annual capacity factors.
What is the difference between electricity generation capacity and electricity generation?
Capacity factors for utility scale generators primarily using fossil fuels
Capacity factors for utility scale generators not primarily using fossil fuels
U.S. nuclear generation and generating capacity (historical monthly capacity and generation by state and reactor)
Nuclear energy (historical monthly and annual data on the total number of U.S nuclear reactors, electricity generation capacity, electricity generation, and capacity factors)
U.S. Nuclear Industry
Nuclear Power Plants
Last updated: March 7, 2022