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Uranium enrichment is the process of increasing the concentration of U235 isotope in natural uranium and decreasing that of U238 isotope
Uranium is a naturally occurring element containing U235 and U238 isotopes. Only the U235 isotope is fissionable. Enrichment is a critical step in transforming natural uranium into nuclear fuel to produce electricity.
Natural uranium contains about 0.7% U235. But the fuel assemblies that power a commercial nuclear reactor at an electric utility generally need uranium with a 4% - 5% concentration of U235. To produce this fuel, USEC increases, or enriches, the concentration of U235 in natural uranium hexafluoride (UF6) to the appropriate level and sells the fuel to its utility customers.
Uranium enrichment is sold as separative work units (SWU), which represent the level of effort required to increase the concentration of U235 in natural uranium. Higher levels of U235 require more SWU.
Commercial uranium enrichment currently employs one of two technologies: gaseous diffusion or gas centrifuge. Both use UF6 as the chemical form of uranium for processing, in part because UF6 readily becomes a gas when heated. Both rely on the mass differences between U235 and U238 to achieve separation, either through a semiporous membrane (diffusion) or by spinning at high speed (centrifuge). At its Paducah, Kentucky, plant, USEC uses the gaseous diffusion method for enriching uranium.
USEC is in the process of demonstrating its next-generation American Centrifuge uranium enrichment technology. USEC is operating a Demonstration Facility in Piketon, Ohio, for the purposes of demonstrating and evaluating the Company’s enhancements to U.S. centrifuge technology and centrifuge performance in a cascade configuration. The Lead Cascade test program began operating in the Demonstration Facility in late August 2007. The American Centrifuge Plant is planned to have an annual production level of approximately 3.8 million SWU.