EFFECT OF URANIUM OXIDATION STATE AND SINTERING ATMOSPHERE ON PHASE FORMATION OF THE CERAMIC WASTEFORM FOR PLUTONIUM DISPOSITION

摘要

Significant quantities of uranium oxide will accompany plutonium oxide designated for disposition in a ceramic form. Additional uranium oxide promotes the formation of the cubic phase pyrochlore and ensures stability of the final form in terms of accommodating decomposition products. Ceramic samples made using uranium oxide as UO_2, U_3O_8 and UO_3 were sintered in air and argon atmospheres to assess the effect of uranium valence state on phase formation, density, and porosity. Cerium oxide was used as a surrogate for plutonium oxide and all other processing conditions were held constant. The sintered pellets were evaluated using x-ray diffraction and scanning electron microscopy. Other properties such as hulk density and apparent porosity were also measured.