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EcoPerspectives (formerly Yggdrasil)

Uranium Enrichment Project

    The Uranium Enrichment Project of Yggdrasil Institute monitored the US uranium enrichment establishment from December 1999 through February 2002. At the time, uranium enrichment was a center of controversy because of issues relating to worker exposure, environmental contamination, the financial condition of the United States Enrichment Corporation, the Russian-US high-enriched uranium agreement, and plans by the United States Enrichment Corporation and the foreign company Urenco to build new enrichment plants using centrifuge technology in the United States.

    For much the same reasons as in 1999-2002, plus very obvious problems concerning nuclear proliferation, uranium enrichment is still a center of controversy in 2006.  We are making available again, for reference, our earlier publications, and hope that we can shortly recommence our monitoring of the subject.

    Uranium enrichment is the process by which the isotopic composition of uranium is modified. Natural uranium consists of three isotopes, uranium 234, uranium 235, and uranium 238, approximately 0.0058%, 0.71% and 99.28% respectively. Uranium 235 unlike uranium 238 is fissile, that is it can sustain a chain reaction. Light water nuclear power plants (the type in the United States) normally operate on fuel containing between 3 and 5% uranium 235 (low-enriched uranium); nuclear weapons are normally fabricated with uranium containing more than 90% uranium 235. Therefore, before natural uranium is used in uranium fuel for light water reactors or for bombs it undergoes "enrichment."

    Enrichment processes transform the natural uranium into two products, enriched uranium with a higher percentage of uranium 235 than natural uranium and depleted uranium (also known as "tails"), with a lower percentage of uranium 235 than natural uranium. The enrichment process in use in the United States is gaseous diffusion. In gaseous diffusion, uranium in the form of gaseous uranium hexafluoride (UF6) is pumped through a succession of diffusion membranes. Uranium 235, which is lighter than uranium 238, passes through the diffusion membranes slightly faster than uranium 238.

    The Atomic Energy Commission constructed three uranium enrichment plants: K-25 at the Oak Ridge Reservation in Tennessee, during World War II; and plants at Paducah, Kentucky, and Piketon, Ohio, in the fifties. All three plants are now owned by the US Department of Energy (DOE), a successor to the Atomic Energy Commission.

    The Oak Ridge plant was permanently shut down in 1987. The site, known as the K-25 site or the East Tennessee Technological Park (ETTP) is undergoing decontamination and "reindustrialization." The United States Enrichment Corporation (USEC) leases from DOE most of the buildings at the Paducah and Piketon sites and operates the Paducah Gaseous Diffusion Plant. The Portsmouth Gaseous Diffusion Plant is on cold standby. Though a private corporation, USEC is responsible for implementing the Russian-US HEU agreement by importing from Russia low-enriched uranium that has been downblended from surplus weapons uranium. DOE remains responsible for site cleanup and for waste produced before USEC took over operation of the plants.The US Nuclear Regulatory Commission has safety, safeguards, and security regulatory responsibility for the two operating plants.


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