Nuclear plants, like plants that burn coal, oil and natural gas, produce electricity by boiling water into steam. This steam then turns turbines to produce electricity. The difference is that nuclear plants do not burn anything. Instead, they use uranium fuel, consisting of solid ceramic pellets, to produce electricity through a process called fission.
Nuclear power plants obtain the heat needed to produce steam through a physical process. This process, called fission, entails the splitting of atoms of uranium in a nuclear reactor. The uranium fuel consists of small, hard ceramic pellets that are packaged into long, vertical tubes. Bundles of this fuel are inserted into the reactor.
Watch NEI's easy-to-understand video tutorial below on the design and safe operation of a nuclear reactor. (Note: Select "Full screen" at the bottom right of the video to see an enlarged version of the video.)
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Two Types of Uranium
Nuclear fuel consists of two types of uranium, U-238 and U-235. Most of the uranium in nuclear fuel is U-238, but U-235 splits—or fissions—easily. In U-235 atoms, the nucleus, which is composed of protons and neutrons, is unstable. As the nuclei break up, they release neutrons.
When the neutrons hit other uranium atoms, those atoms also split, releasing neutrons of their own, along with heat. These neutrons strike other atoms, splitting them. One fission triggers others, which triggers still more until there is a chain reaction. When that happens, fission becomes self-sustaining.
Rods inserted among the tubes holding the uranium fuel control the nuclear reaction. Control rods, inserted or withdrawn to varying degrees, slow or accelerate the reaction.
Water separates fuel tubes in the reactor. The heat produced by fission turns this water into steam. The steam drives a turbine, which spins a generator to create electricity.