Uranium Metal and Alloys
Source: Appendix A of the PEIS (DOE/EIS-0269)
Uranium metal appears as a heavy, silvery white, malleable, ductile, softer-than-steel, metallic element. It is one of the densest materials known (19 g/cm3), being 1.6 times more dense than lead. Uranium metal is not as stable as U3O8 or UF4 because it is subject to surface oxidation. It tarnishes in air, with the oxide film preventing further oxidation of massive metal at room temperature. Water attacks uranium metal slowly at room temperature and rapidly at higher temperatures. UO2 and uranium hydride (UH3) are formed while heat is evolved, and the metal swells and disintegrates. It melts at 1,132°C.
Uranium powder or chips will ignite spontaneously in air at ambient temperature. During storage, uranium ingots can form a pyrophoric surface because of reaction with air and moisture. Uranium metal will also react with water at ambient temperature, forming UO2 and UH3. The metal swells and disintegrates. Hydrogen gas can be released.
Solid uranium, either as chips or dust, is a very dangerous fire hazard when exposed to heat or flame. In addition, uranium metal can react violently with chlorine (Cl2), fluorine (F2), nitric acid (HNO3), selenium (Se), sulfur (S), ammonia (NH3), bromine fluoride (BrF3), trichloroethylene (TCE), or nitryl fluoride and similar compounds.