Explain how a nuclear power plant uses the process of nuclear fission to produce electricity.

The primary objective of a reactor is to house and control nuclear fission—a process where atoms split and release energy. Reactors use uranium for nuclear fuel. The uranium is processed into small ceramic pellets and stacked together into sealed metal tubes called fuel rods. A reactor core is typically made up of a couple hundred assemblies, depending on power level.   Inside the reactor vessel, the fuel rods are immersed in water which acts as both a coolant and moderator. The moderator helps slow down the neutrons produced by fission to sustain the chain reaction. Control rods can then be inserted into the reactor core to reduce the reaction rate or withdrawn to increase it. The heat created by fission turns the water into steam, which spins a turbine to produce carbon-free electricity.