UO3

Uranium trioxide, UO3, is an inorganic compound of uranium in the +6 oxidation state. It exists as several polymorphs, with alpha-UO3 and beta-UO3 among the most commonly reported forms. In appearance it is typically a yellow-orange powder and, in many samples, exists as hydrates or as oxide hydrates under ambient conditions.

Preparation and occurrence: UO3 is produced commercially as an intermediate in the processing of uranium ore concentrates. It can be formed by controlled oxidation of UO2 or of uranyl compounds, using oxidants such as oxygen or nitric acid at elevated temperature. It may also arise from dehydration of hydrated uranyl oxides or uranyl salts.

Chemical properties: UO3 is a strong oxidizer and tends to absorb moisture, forming hydrates. It is unstable at elevated temperatures and readily converts to higher oxides such as U3O8 or, under reducing conditions, to UO2.

Uses and applications: In the nuclear fuel cycle, UO3 is an intermediate that can be reduced to UO2, which is the common reactor fuel, or converted to other uranium compounds for processing. It is encountered primarily in ore processing, chemical conversion, and waste handling rather than as a finished material.

Safety: Like other uranium compounds, UO3 is radioactive and chemically toxic. Handling requires appropriate radiological controls, ventilation, protective equipment, and proper disposal.