Nuclear reactors look like large concrete 

domes from the outside. Not all nuclear 

power plants have cooling towers.

Source: Stock photography (copyrighted)

Nuclear Power Plants – Basics

Nuclear Power Plants Generate About One-Fifth of U.S. Electricity 

Nuclear power accounted for slightly more than 19% of the total net electricity generated in the United States in 2011, 

about as much as the electricity used in California, Texas, and New York, the three states with the most people. In 

2010, there were 65 nuclear power plants (composed of 104 licensed nuclear reactors) throughout the United States. 

Most of the reactors are east of the Mississippi. The last new reactor to enter commercial service in the United States 

was the Tennessee Valley Authority’s Watts Bar 1 in Tennessee in 1996. 

In 2008, TVA resumed construction on Watts Bar 2, which was partially complete when its construction was stopped in 

1988. It is now expected to be completed in 2013.

By early 2011, the Nuclear Regulatory Commission (NRC) had 

received applications for a total of 28 newly designed reactors. It is 

uncertain how many of these reactors will eventually be built, but the 

NRC estimates 42 months to complete the review of all the 

applications prior to a final decision. Construction typically requires 

another five to seven years for each reactor. 

Nuclear Power Comes from Fission

Most power plants, including nuclear plants, use heat to produce 

electricity. They rely on steam from heated water to spin large 

turbines, which generate electricity. Instead of burning fossil fuels to 

produce the steam, nuclear plants use heat given off during fission. 

In nuclear fission, atoms are split apart to form smaller atoms, 

releasing energy. Fission takes place inside the reactor of a nuclear 

power plant. At the center of the reactor is the core, which contains the 

uranium fuel. 

The uranium fuel is formed into ceramic pellets. The pellets are about the size of your fingertip, but each one produces 

roughly the same amount of energy as 150 gallons of oil. These energy-rich pellets are stacked end-to-end in 12-foot 

metal fuel rods. A bundle of fuel rods, sometimes hundreds, is called a fuel assembly. A reactor core contains many 

fuel assemblies.

The heat given off during fission in the reactor core is used to boil water into steam, which turns the turbine blades. As 

they turn, they drive generators that make electricity. Afterward, the steam is cooled back into water in a separate 

structure at the power plant called a cooling tower. The water can be used again and again.

Learn More

■ U.S. Nuclear Reactor, Capacity and Generation — http://www.eia.gov/nuclear/reactors/stats_table1.html

■ State Nuclear Profiles — http://www.eia.gov/cneaf/nuclear/state_profiles/nuc_state_sum.html

Explaining Nuclear Energy for Kids — http://www.washingtonpost.com/lifestyle/style/explaining-nuclear-energyfor-kids/2011/03/15/ABhFsfl_story.html■

Last Updated: April 25, 2012

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