There are currently 104 operable commercial nuclear reactors at 65 nuclear power plants. Since 1990, the share of the nation's total electricity supply provided by nuclear power generation has averaged about 20%, with increases in nuclear generation that have roughly tracked the growth in total electricity output. Between 1985 and 1996, 34 new reactors were placed in service. In addition, nuclear generation has increased as a result of higher utilization of existing capacity and from technical modifications to increase nuclear plant capacity. Partly in response to incentives provided by the Energy Policy Act of 2005, including new construction loan guarantees for new nuclear power plants, EIA expects nuclear power output to grow, although at a rate about half that of total electricity generation.
Most of the commercial reactors in the United States are located east of the Mississippi River, near water sources (see map below). Illinois has the most reactors (11) and the most nuclear capacity. The three largest reactors in the United States, each with capacities above 1,300 net megawatts, are located at the Palo Verde plant in Arizona. The smallest reactor (478 net megawatts) is at Fort Calhoun, Nebraska.
A power plant refers to an entire facility. A plant may contain nuclear as well as non-nuclear units. Each reactor located at a commercial nuclear plant is part of a unique nuclear generating unit with its own personnel, equipment, and generators. The reactor provides heat to make steam, which drives a turbine and in turn drives the generator, which provides electricity.
More than half of the U.S. nuclear plants have at least two reactors. Although some foreign nuclear power plants have as many as eight reactors, only three U.S. plants have more than two operational reactors: Palo Verde in Arizona, Browns Ferry in Alabama, and Oconee in South Carolina each have three reactors.
In February 2012, the U.S. Nuclear Regulatory Commission voted to approve Southern Company's application to build and operate two new nuclear reactors, Units 3 and 4, at its Vogtle plant. The Vogtle units are the first reactors to receive construction approval in over 30 years, and are expected to be operational in 2016 and 2017. See related Today in Energy article, March 5, 2012.
The last new reactor to enter commercial service was the Tennessee Valley Authority's (TVA) Watts Bar 1 in Tennessee in 1996. In 2002, the TVA returned Browns Ferry Unit 1 to service; the unit had been shut down since 1985. In 2007, construction resumed on a partially built reactor, Watts Bar 2, which is slated for initial operation in 2013. Construction on two other reactors, Bellefonte 1 and 2 in Alabama, remains suspended, but TVA has left open the possibility that the reactors eventually might be completed.
All of the TVA projects mentioned involve re-starting old, partially built nuclear projects. Prospects for the construction of brand new plants are discussed below.
Natural gas represents the largest share of electric power generation capacity, followed by coal, nuclear power, and conventional hydropower. Natural gas and coal capacity are each much larger than nuclear capacity (see capacity figure at left). However, for cost and technical reasons, nuclear power plants are generally utilized more intensively than coal or natural gas units. In 2011, the nuclear share of electricity generating capacity was 9%, while nuclear's share of national power output was 19%. The comparable values for coal and natural gas were 28% capacity to 42% generation for coal, and 41% capacity to 25% generation for natural gas.
The United States has the most nuclear capacity and generation among the 31 countries in the world that have commercial nuclear power. France, the country with the second most nuclear capacity, relies on nuclear power for nearly 80% of its electricity. Other countries that get a significant share of their electricity from nuclear power include Russia, Japan, South Korea, and Germany.
Japan's nuclear power generation was significantly curtailed in the aftermath of the March 11, 2011 Tohoku earthquake and accompanying tsunami, which led to the accident at Tokyo Electric Power Company's (TEPCO) Fukushima Daiichi nuclear power plant and subsequent outages at other plants. In 2011, nuclear plants in Japan generated 156 billion KWh of electricity compared to 280 billion KWh in 2010. See related Today in Energy article, May 30, 2012.
Nuclear waste is a solid waste that must be carefully stored because it contains radioactive material and may be harmful if exposed. Currently, most commercial nuclear wastes are stored on-site at nuclear plants. See the U.S. Nuclear Regulatory Commission for more information on nuclear waste.
Nuclear power generation itself does not contribute to airborne emissions of carbon dioxide (CO2), a major greenhouse gas, although related activities such as the production of nuclear fuel for reactors do result in CO2 emissions. Currently, its nearest competitor in size among non-greenhouse-gas-emitting electricity generating technologies is conventional hydropower, which accounts for about 6% of U.S. electricity generation.
Although five nuclear plants were retired in 1997 and 1998, nuclear capacity is about the same as in 1996 when the Watts Bar 1 plant came on line. Technical modifications to increase capacity (called uprates) at existing plants have made this possible. These uprates, combined with high utilization, have enabled nuclear to consistently maintain a share of about 20% of total electricity output. With many nuclear plants operating at or near capacity, even maintaining the current share will depend on new reactors being built as electricity demand increases. However, four new reactors (Vogtle Units 3 and 4 and Summer Units 2 and 3) are expected to come online between 2016 and 2017.
As of early 2012, the NRC has active applications for a total of 28 new reactors, although it is unknown how many of the proposed reactors will be built. The NRC application review process is a detailed review that takes 30 to 60 months. Items as such reactor design information, site evaluation, and safety features of the proposed plant are included in the review. Construction may take around six years for each reactor. EIA projects that the industry will add approximately 19.1 gigawatts (19,100 megawatts) of new nuclear capacity during the period 2012 to 2040, with 11.0 gigawatts coming from new reactors and 8.0 gigawatts coming from uprates of existing plants.1
1See Annual Energy Outlook 2013 Early Release with Projections to 2040 December 2012).
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. nuclear power plant at Shippingport, Pennsylvania, in 1957.
Annual nuclear generation in the United States has remained steady in recent years.
The Grand Coulee Dam in the state of Washington has the most capacity of any electric power plant in the United States, at 7,079 net megawatts. The Palo Verde nuclear plant in Arizona ranks second with a capacity of 3,937 net megawatts. But nuclear plants are able to use more of their capacity than hydropower facilities. In 2011, Grand Coulee generated over 24,567 gigawatthours of electricity, while Palo Verde generated more than 31,278 gigawatthours.
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