SURFACE CHEMICAL BEHAVIOR OF TRIURANIUM OCTAOXIDE IN THE ATMOSPHERES OF CARBON-MONOXIDE AND HYDROGEN

The surface chemical behavior of U3O8 has been studied by X-ray photoe lectron spectroscopy (XPS), gas chromatography (GC) and thermodynamic calculations in reducing atmospheres. The surface of U3O8 is remarkabl y reduced in the atmospheres of CO and H-2. The effect of the oxide re duction is more obvious at higher temperatures and the oxygen content in the oxide is decreased with increasing exposure to the gases. The i nfluence of H-2 is less than that of CO. It is also shown that the oxi de surface layer is resistant to further hydriding as there does not e xist any hydriding reaction for U3O8 in a H-2 atmosphere. Results of G C investigations and thermodynamic calculations are in good agreement with the above conclusions. (C) 1998 Elsevier Science B.V. All rights reserved.