Carbothermic reduction of uranium oxides into solvent metallic baths

The carbothermic reduction of UO2 and U3O8 is studied employing tin and silicon solvent metallic baths in thermal analysis equipment, under Ar inert and N2 reactive atmospheres. The metallic solvents are expected to lower the U activity by several orders of magnitude owing to strong interactions among the metals. The reduction products are composed of the solvent metal matrix and intermetallic U compounds. Silicon is more effective in driving the reduction since there is no residual UO2 after the reaction. The gaseous product detected by mass spectrometer (MS) during the reduction is CO. A kinetic study for the Si case was accomplished by the stepwise isothermal analysis (SAI) method, leading to the identification of the controlling mechanisms as chemical reaction at the surface and nucleation, for UO2 and U3O8 charges, respectively. One example for another system containing Al2O3 is also shown.