Nuclear power comes from nuclear fission
Nuclear power plants heat water to produce steam. The steam is used to spin large turbines that generate electricity. Nuclear power plants use heat produced during nuclear fission to heat water.
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 uranium fuel.
The uranium fuel is formed into ceramic pellets. Each ceramic pellet produces about 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, some with hundreds of rods, is called a fuel assembly. A reactor core contains many fuel assemblies.
The heat produced during nuclear fission in the reactor core is used to boil water into steam, which turns the blades of a steam turbine. As the turbine blades turn, they drive generators that make electricity. Nuclear plants cool the steam back into water in a separate structure at the power plant called a cooling tower or they use water from ponds, rivers, or the ocean. The cooled water is then reused to produce steam.
Nuclear power plants generate about 20% of U.S. electricity
As of January 2018, there were 99 operating nuclear reactors at 61 nuclear power plants in 30 states. Thirty-six of the plants have 2 or more reactors. Nuclear power has supplied about one-fifth of total annual U.S. electricity since 1990.
The United States generates more nuclear power than any other country
Of the 31 countries in the world with commercial nuclear power plants in 2015, the United States had the most nuclear electricity generation capacity and generated more electricity from nuclear energy than any other country. France had the second-highest nuclear electricity generation capacity and electricity generation and obtained about 78% of its total electricity generation from nuclear energy, the largest share of any other country. Fourteen other countries generated at least 20% of their electricity from nuclear power.
Top five nuclear electricity generation countries, 2015