UF6

Uranium hexafluoride, UF6, is a chemical compound of uranium and fluorine used primarily in the uranium enrichment stage of the nuclear fuel cycle. At ambient conditions it is a white crystalline solid, but it readily vaporizes to a gaseous form that can be fed into enrichment equipment such as gas centrifuges or gaseous diffusion plants. Its suitability for enrichment comes from being volatile in the right temperature range while remaining chemically reactive with fluorine.

Chemical and physical properties: UF6 has a high molecular weight and is highly reactive with moisture. When it hydrolyzes in the presence of water, it forms uranyl fluoride (UO2F2) and hydrogen fluoride (HF), both of which are corrosive and toxic. The uranium in UF6 is radioactive, presenting radiological hazards in addition to its chemical toxicity. Handling and processing typically require specialized, corrosion-resistant equipment and closed systems to prevent release and exposure.

Production and handling: Industrially, UF6 is produced by fluorinating uranium tetrafluoride (UF4) with fluorine gas at elevated temperatures: UF4 + F2 → UF6. Because UF6 is volatile, it is stored and transported in robust steel cylinders with compatible inner linings. Facilities using UF6 employ leak detection, containment, HF scrubbing, and strict security and regulatory controls to mitigate chemical, radiological, and proliferation risks.

Uses and regulation: The principal use of UF6 is to prepare uranium for enrichment, increasing the proportion of the fissile isotope 235U. After enrichment, UF6 is converted to fuel forms such as UO2 for reactor fuel fabrication. Due to its dual hazards and potential role in weapons proliferation, UF6 handling is subject to stringent national and international regulatory controls.