solid ceramic uranium fuel pellets

Nuclear power plants don't burn fuel in the conventional sense

The difference between a nuclear power plant and a fossil-fuel power plant is the heat source. A fossil-fueled (coal, oil, gas) power plant uses oxygen to burn the fuel and create steam to spin the generator.  This process produces carbon dioxide as a byproduct. 

In contrast, nuclear reactors use enriched uranium as their heat source. The uranium atoms create heat by splitting; the technical term for this process is fission.  Fission requires no oxygen and produces no carbon dioxide.

Uranium fuel comes to the power plant in the form of small, solid ceramic pellets. The electricity produced by one fuel pellet, roughly the size of a pencil eraser, is equal to the amount produced by 4.5 barrels of oil or one ton of coal.

Inside the reactor, pellets of uranium are stacked end-to-end in 12-foot long tubes, or fuel assemblies. These fuel assemblies are precisely arranged in bundles within the reactor with spaces between the bundles for control rods.  The control rods can be moved in and out of the reactor to stop and start the fission process.

Our Fermi 2 plant contains 185 control rods and 764 zirconium alloy fuel assemblies.  Each assembly contains approximately 13,000 uranium pellets.