View source for Uranium hexafluoride

[[Category:Done 2016-04-30]] 
[[File:Uranium-hexafluoride-3D-vdW.png|300px|thumb|right|Figure 1. The blue atom in the centre of the molecule is uranium, surrounded by six fluorine atoms. This substance becomes a gas at fairly low [[temperature]]s.]]
[[File:Uranium_hexafluoride_crystals_sealed_in_an_ampoule.jpg|300px|thumb|right|Figure 2. A sample of solid uranium hexafluoride crystals in a tube.<ref>Wikimedia Commons. (January 7, 2016). ''Uranium Hexafluoride Crystals'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/9/94/Uranium_hexafluoride_crystals_sealed_in_an_ampoule.jpg</ref>]]
<onlyinclude>'''Uranium hexafluoride''' - with the [[chemical]] formula '''UF<sub>6</sub>''' - is a chemical compound that contains one atom of [[uranium]] and six atoms of [[fluorine]] (see figure 1). In its [[solid]] form, uranium hexafluoride is a white crystalline substance (see figure 2). This uranium compound is used during the [[uranium enrichment]] process.</onlyinclude><ref name="RE1">Argonne National Laboratory. (January 7, 2016). ''Uranium Hexafluoride'' [Online]. Available: http://web.ead.anl.gov/uranium/guide/uf6/</ref>

Since all enrichment technologies used on an industrial scale require some [[gas]]eous medium, uranium hexafluoride is used widely because of its chemical properties, mainly its ability to change state over a fairly small range of [[temperature]]s.<ref name="RE3">URENCO. (January 8, 2016). ''Uranium Hexafluoride'' [Online]. Available: http://www.urenco.com/about-us/business-activity/nuclear-fuel-supply-chain/uranium-hexafluoride/</ref> Uranium hexafluoride is used widely in uranium processing as it can conveniently be used as a gas for processing, but can also be transported and stored as a solid or [[liquid]] without the use of extreme [[pressure]]s or temperatures.

==Uses==
Uranium hexafluoride is used primarily in the [[gaseous diffusion]] and [[gaseous centrifuge]] processes that are used to enrich uranium. In gaseous [[diffusion]], mined uranium ore is sent to a plant that produces [[uranium oxide]], more commonly known as "[[yellowcake]]". Next, uranium oxide is combined with hydrogen fluoride and fluorine gas to chemically form the uranium hexafluoride.<ref name="RE1"/> For a more in depth look into the UF<sub>6</sub> conversion process sea the [[uranium enrichment]] page. For the gaseous diffusion to take place, the uranium hexafluoride must be heated as it is solid under normal conditions, but transforms into a gas if the temperature is raised slightly or the pressure is lowered.<ref name="RE2">Jeff C. Bryan. (January 8, 2016). ''Introduction to Nuclear Science'', 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> Since the <sup>235</sup>UF<sub>6</sub> molecules are slightly lighter than the <sup>238</sup>UF<sub>6</sub> molecules, they move more quickly as a gas through diffusion. Thus if uranium hexafluoride is passed through a very long pipe, the gas that emerges at the far end of the pipe will have a slightly higher percentage of <sup>235</sup>U. However, the pipe must be extremely long as the lighter <sup>235</sup>UF<sub>6</sub> diffuses only 0.43% faster than <sup>238</sup>UF<sub>6</sub>.<ref name="RE2"/>

==Safety==
Uranium hexafluoride is not [[flammable]] or explosive, however it does react with [[water]]. When exposed to water, uranium hexafluoride undergoes rapid conversion into uranyl fluoride and hydrogen fluoride. If it is exposed to excess levels of water, the hydrogen fluoride then forms hydrofluoric acid, which poses a burn risk.<ref name="RE3"/>

Uranium hexafluoride is transported worldwide in special transport containers in a solid form. During transport, the pressure inside these containers is maintained below atmosoheric pressure to ensure the uranium remains in solid form.<ref name="RE3"/>

==References==
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