What is uranium hexafluoride (UF6)?
Uranium hexafluoride is a chemical compound consisting of one atom of uranium combined with six atoms of fluorine. It is the chemical form of uranium that is used during the uranium enrichment process. Within a reasonable range of temperature and pressure, it can be a solid, liquid, or gas. Solid UF6 is a white, dense, crystalline material that resembles rock salt. Liquid UF6 is formed only at temperatures greater than 147° F (64° C) and at pressures greater than 1.5 times atmospheric pressure (22 psia). At atmospheric pressure, solid UF6 will transform directly to UF6 gas (sublimation) when the temperature is raised to 134° F (57° C), without going through a liquid phase.
Uranium hexafluoride does not react with oxygen, nitrogen, carbon dioxide, or dry air, but it does react with water or water vapor. For this reason, UF6 is always handled in leak tight containers and processing equipment. When UF6 comes into contact with water, such as water vapor in the air, the UF6 and water react, forming corrosive hydrogen fluoride (HF) and a uranium-fluoride compound called uranyl fluoride (UO2F2).
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