How is Atomic Energy Produced?
Worldwide there are more than 430 nuclear power plants operating in 31 countries. In the U. S. alone there are 104 nuclear plants that supply approximately 20 percent of the nation's electricity use, and over 30 research and test reactors located at universities and research institutions throughout the country. The University of Missouri in Columbia operates the most powerful of the research reactors. In addition to training students, the small reactor provides commercial isotopes and other services for medical, industrial, and research applications.
Commercial plants generate electricity by utilizing fission reactions to heat water and produce steam. All commercial nuclear plants in the U.S. and most of the plants in western Europe are light water reactors that use ordinary water as a coolant and moderator. The two types of light water reactors most commonly used are pressurized water and boiling water reactors. Of the 104 commercial reactors in the U.S., 69 are pressurized water reactors and 35 are boiling water reactors. The nuclear power stations closest to Kansas City, the Wolf Creek plant near Burlington, Kansas, and the Callaway plant near Fulton, Missouri, utilize pressurized light-water reactor systems.
Producing Energy With a Pressurized Water Reactor
In a pressurized water reactor very pure water is heated to extremely high temperatures through the fissioning of uranium. Fission occurs in the central portion of a nuclear reactor known as the core. The core contains fuel assemblies that house the uranium, a moderator, and control rods. Thin metal tubes within a fuel assembly hold pellets of fissionable material necessary for the nuclear reactors. The pellets are made from enriched U-235, the fissile isotope of uranium. In the U. S. uranium is enriched by gaseous diffusion, a process that filters uranium hexafluoride gas through a porous membrane to separate the lighter isotopes U-234 and U-235 from the heavier U-238 isotope. This process, called enrichment, increases the percentage of U-235 found in natural uranium ore from one percent to three percent. A fuel fabrication process then converts the enriched uranium into uranium dioxide powder that is formed into fuel pellets.
Fission heats water as it circulates through the reactor. The water is kept under high pressure to prevent it from boiling. A generator converts the water to steam that powers a turbine generator to produce electricity. The unused steam is condensed into water, reheated, and pumped back to the steam generator. The electrical current passes through a transformer and away from the plant on high-voltage lines.