U.S. Energy Information Administration logo

Frequently Asked Questions

How much electricity does a nuclear power plant generate?

As of December 3, 2018, there were 99 operating nuclear reactors at 61 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 an electricity generating capacity1 of 582 megawatts (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 electricity generating capacity1 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 it operates 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 every day of the year, it would generate 5,098,320 MWh. However, most power plants do not operate a full capacity every hour of every day of the year. In 2017, the R. E. Ginna nuclear power plant actually generated 4,697,675 MWh.. 

Nuclear power reactors generally operate at or near their rated generating capacity throughout the year and have relatively high annual capacity factors.

1 Net summer capacity.

Learn more:
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: December 4, 2018

Other FAQs about Nuclear