Influence of texture and physical mixture of UO₃ and C powders for carbothermal reduction

Abstract : The carboreduction of uranium UO₃ into uranium dioxide UO₂ has been studied using two distinct mixtures of uranium trioxide and carbon powders, containing an excess of carbon (C/U=3 mole ratio). The specific surface area and the porous distribution of these mixtures were characterized by nitrogen adsorption, and thermogravimetry experiments were performed under flowing helium, up to 900°C, in order to characterize the reactivity of the mixtures. The course of the carbothermal reduction depends on the texture and the physical mixture of uranium trioxide and carbon: optimal reduction was obtained after a slight manual grinding of the initial mixture (UO₃ + 3C), which improved the contact between uranium trioxide and carbon.