U.S. Energy Information Administration logo
Skip to sub-navigation

Nuclear explained U.S. nuclear industry

What is the status of the U.S. nuclear industry?

Electricity generation from commercial nuclear power plants in the United States began in 1958. At the end of December 2019, the United States had 96 operating commercial nuclear reactors at 58 nuclear power plants in 29 states. The average age of these nuclear reactors is about 38 years old. The oldest operating reactor, Nine Mile Point Unit 1 in New York, began commercial operation in December 1969. The newest reactor to enter service, Watts Bar Unit 2, came online in 2016—the first reactor to come online since 1996 when the Watts Bar Unit 1 came online. According to the U.S. Nuclear Regulatory Commission as of November 2019, there were 17 shut down commercial nuclear power reactors at 16 sites in various stages of decommissioning.

Although in 2019 there were fewer operating nuclear reactors than in 2013, total nuclear electricity generation capacity at the end of 2019 was about the same as total capacity in 2003, when the United States had 104 operating reactors. Power plant uprates—modifications to increase capacity—at nuclear power plants have made it possible for the entire operating nuclear reactor fleet to maintain a relatively consistent total electricity generation capacity. These uprates, combined with high capacity utilization rates (or capacity factors), have helped nuclear power plants maintain a consistent share of about 20% of total annual U.S. electricity generation since 1990. Some reactors have also increased annual electricity generation by shortening the length of time reactors are offline for refueling.

did youknow


On December 2, 1942, under the bleachers of the football stadium at the University of Chicago, Dr. Enrico Fermi initiated the first controlled nuclear chain reaction. The experiment, conducted as part of the wartime atomic bomb program, also led to peaceful uses of the atom, including construction of the first U.S. commercial nuclear power plant at Shippingport, Pennsylvania, in 1958.

Click to enlarge

Twenty nine states have at least one commercial nuclear reactor

Most U.S. commercial nuclear power reactors are located east of the Mississippi River. Illinois has more reactors than any state (11 reactors at 6 plants), and at the end of 2019, it had the largest total nuclear net summer electricity generation capacity at about 11,582 megawatts (MW). The Grand Gulf Nuclear Station in Port Gibson, Mississippi, has the largest U.S. nuclear reactor with an electricity generating capacity of about 1,400 MW. The two smallest operating reactors, each with a net summer generating capacity of about 520 MW, are at the Prairie Island nuclear plant in Red Wing, Minnesota. Two new nuclear reactors are under construction in Georgia, each with a planned electricity generation capacity of about 1,100 MW.

Map of United States showing approximate locations of U.S. nuclear power plants as of April 2020

Click to enlarge

did youknow


The Grand Coulee Dam in Washington has the most electricity generation capacity of any electric power plant in the United States—7,079 megawatts (MW) net summer capacity. The Palo Verde nuclear power plant in Arizona, with three reactors, has the second-largest generating capacity—3,937 MW. Nuclear power plants generally use more of their electricity generating capacity on an annual basis than hydropower facilities. In 2019, Grand Coulee generated about 17 million megawatthours of electricity, while Palo Verde generated about 32 million megawatthours.

Many nuclear power plants have more than one reactor

The term power plant refers to an entire facility. A power plant may contain nuclear as well as non-nuclear electricity generating units. Each nuclear reactor located at a commercial nuclear power plant is unique and has its own personnel and equipment. The reactor provides heat to make steam, which drives a turbine that, in turn, drives the generator that produces electricity.

Thirty-five U.S. nuclear power plants have at least two reactors. Although some foreign nuclear power plants have as many as eight reactors, only three U.S. nuclear power plants have more than two operating reactors: Palo Verde Nuclear Generating Station in Arizona, Browns Ferry Nuclear Power Plant in Alabama, and Oconee Nuclear Station in South Carolina. All three plants have three reactors.

Nuclear power plants are generally used more intensively than other power plants

For cost and technical reasons, nuclear power plants are generally used more intensively than coal- or natural gas-fired power plants. In 2019, the nuclear share of total U.S. electricity generating capacity was 9%, while the nuclear share of total electricity generation was about 20%.

Click to enlarge

Recent U.S. nuclear construction activity

In 2016, the Tennessee Valley Authority's (TVA) Watts Bar Unit 2 in Tennessee became the first new U.S. reactor to come online since 1996.

In February 2012, the U.S. Nuclear Regulatory Commission (NRC) voted to approve Southern Company's application to build and operate two new reactors, Units 3 and 4, at its Vogtle plant in Georgia. The new Vogtle reactors are the first new reactors to receive construction approval in more than 30 years.

In March 2012, the NRC voted to approve South Carolina Electric and Gas Company's application to build and operate two new reactors, Units 2 and 3, at its Virgil C. Summer plant in South Carolina. However, construction on these reactors stopped in 2017.

When will new reactors in the United States come online?

The two new reactors that are now under construction—Vogtle Units 3 and 4—in Georgia are expected to come online between 2021 and 2022.

The NRC issues license applications for new reactors in various stages of review. The NRC application review process can take up to five years to complete. Under current licensing regulations, a company that seeks to build a new reactor can use reactor designs that the NRC has previously approved. The design certification the NRC issues is independent of approvals of applications to construct or operate a new nuclear power plant. When the applicant uses an NRC-certified reactor design, that means that all safety issues related to the design have been resolved, and the focus of the NRC's review is the quality of construction. Construction of a nuclear power plant may take five years or more.

The U.S. Energy Information Administration (EIA) projects in the Annual Energy Outlook 2020 Reference case that new nuclear electricity generation capacity will be added in 2021 and 2022, but capacity retirements and derating of some reactors will result in less total nuclear electricity generation capacity in 2050 than than in 2019.

Last updated: April 15, 2020