UOx

UOx is an informal shorthand used in some scientific and industrial contexts to refer to uranium oxide materials. It does not denote a single compound but a family of oxides of uranium, including UO2, U3O8, and UO3. The term is most commonly encountered in discussions of the nuclear fuel cycle and ore processing.

Chemical forms and oxidation states: UO2 (uranium dioxide) contains uranium in the +4 oxidation state and is the principal ceramic fuel for light-water reactors. UO3 and U3O8 are higher-oxidation-state oxides; U3O8 contains uranium in mixed +4 and +6 states and is the dominant oxidation product in milled ore (yellowcake). Non-stoichiometric oxides, sometimes described as UOx with x between about 2 and 3, can exist under varying storage or processing conditions.

Production and processing: Uranium ore is milled to produce yellowcake, typically as U3O8. Yellowcake is converted to uranium hexafluoride (UF6) for enrichment, and then reduced to UO2 for fuel pellets. Handling and processing of UOx materials require radiological controls and compliance with nuclear-safety regulations.

Applications and history: UOx materials serve as nuclear fuel and as source material for research reactors. Historically, uranium oxides have also been used as pigments in ceramics and glass, such as uranium yellow, though such uses have declined due to safety and regulatory concerns.

Safety and regulation: Uranium oxides are radioactive and chemically toxic. Inhalation or ingestion of dust can pose health risks, and operations involving UOx are subject to stringent regulatory controls, monitoring, and protective measures to limit exposure and environmental release.

See also: Uranium, Uranium oxide, Nuclear fuel cycle.