Uranium is the fuel most widely used by nuclear power plants for nuclear fission. In nuclear fission, energy is released when atoms are split apart to form smaller atoms. Nuclear power plants use the heat from nuclear fission to produce electricity.
Uranium is a common metal, but it must be processed into a fuel
Uranium is a common metal found in rocks all over the world. Uranium occurs in combination with small amounts of other elements. Economically recoverable uranium deposits have been discovered primarily in the western United States, Australia, Canada, Central Asia, Africa, and South America.
Nuclear power plants use a certain type of uranium, U-235, as fuel because its atoms are easily split apart. Although uranium is about 100 times more common than silver, U-235 is relatively rare.
After uranium is mined, the U-235 must be extracted and processed before it can be used as a fuel. Mined uranium ore typically yields one to four pounds of uranium concentrate (U3O8 or yellowcake) per ton, or 0.05% to 0.20% yellowcake.
Source: U.S. Energy Information Administration (public domain)