A uranium centrifuge is one of several ways to enrich uranium. Like iron ore, uranium ore is found in the ground and must be processed to produce uranium oxide. Uranium oxide has two isotopes, U-238 and U-235. U-238 constitutes about 99 percent of uranium oxide. To produce a controlled nuclear reaction, like the kind used for nuclear power, the two isotopes need to be separated from one another, and the amount of U-235 must be increased, as highly concentrated U-235 metal is what is used for nuclear bombs and to power nuclear reactors. In the United States, a process called gaseous diffusion is used to separate the atoms instead, although some plants have received licenses to develop commercial facilities with gas centrifuge enrichment [source: Nuclear Regulatory Commission]. Many other countries of the world -- including the Netherlands, Germany, United Kingdom, Russia and Japan -- use uranium gas centrifuge enrichment [source: Global Security].
Applying centrifugal force to separate isotopes was first proposed in 1919, but not successful until 1934. In that year, J.W. Beams and colleagues at the University of Virginia used a vacuum centrifuge to separate chlorine isotopes. Gas centrifuge was first used for uranium in the U.S. in the 1940s but set aside when gas diffusion was found to be simpler [source: World Nuclear Association].
To enrich uranium using a gas centrifuge, uranium hexafluoride gas is spun inside a centrifuge, or a container with a cylinder rotor that spins rapidly -- about 400 to 500 meters per second (1,312 to 1,640 feet per second) -- and generates a force thousands of times greater than gravity. The U-238 atoms are heavier and gravitate toward the outside of the centrifuge and increase slightly in number after the process is completed. The lighter U235 gas molecules collect near the center of the cylinder. The gas is transferred to another centrifuge and the process is repeated. Uranium enrichment plants contain chains of thousands of centrifuges, each one feeding into the next. The result is a high concentration of U-235 atoms in uranium hexafluoride.
Electrical power is critical to the operation of gas centrifuge plants, but this form of uranium enrichment still uses less power than gas diffusion [source: Global Security]. The U.S. is looking into developing laser enrichment and funding to help boost continued construction of halted gas diffusion projects [source: World Nuclear Association].
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