Product

Uranium hexafluoride (UF₆), commonly referred to as "hex" in the nuclear industry, is an inorganic compound consisting of one uranium atom bonded to six fluorine atoms. At room temperature (20°C), UF₆ exists as a colorless to white crystalline solid with a density of 5.06 g/cm³, but it sublimes directly to a gas at 56.5°C at atmospheric pressure, making it the only stable volatile uranium compound. This unique volatility property makes UF₆ essential for uranium enrichment processes, particularly gaseous diffusion and gas centrifugation, where the slight mass difference between ²³⁵UF₆ and ²³⁸UF₆ isotopologues enables physical separation.

Chemical Properties

UF₆ is a highly reactive compound and a strong fluorinating agent that reacts vigorously with water to produce uranyl fluoride (UO₂F₂) and hydrofluoric acid (HF), both of which are corrosive and toxic. The compound reacts instantaneously with hydrogen at room temperature and attacks many metals, including sodium and mercury in the cold state, while lead, zinc, tin, and iron react upon heating. With organic compounds such as alcohols, ethers, and aromatic hydrocarbons, UF₆ causes immediate fluorination, producing HF and carbonaceous material. It also acts as a Lewis acid and can form complexes such as heptafluorouranate(VI) [UF₇]⁻.

Production and Applications

UF₆ is produced by converting uranium dioxide (UO₂) with hydrofluoric acid to form uranium tetrafluoride (UF₄), which is then oxidized with elemental fluorine at elevated temperatures. Following enrichment to increase the ²³⁵U content from natural levels (0.7%) to reactor-grade levels (3.5-5%), the enriched UF₆ is converted to uranium dioxide powder for fabrication into nuclear fuel pellets. The compound's radioactivity derives from its uranium component, which emits primarily alpha and gamma radiation.

References

1. Wikipedia. Uranium hexafluoride (last edited on Sep 26 Sep, 2025)
2. WNTI. WNTI Fact Sheet Uranium Hexafluoride (UF6)
3. U.S. Department of Energy (DEA), Office of Scientific and Technical Information (OSTI). Technical Report: Chemical Properties of Uranium Hexafluoride, UF6 (Jun 25, 1941)
4. BENCHCHEM. Uranium hexafluoride
5. Energy Education. Uranium hexafluoride