Sintering investigations of a UO2-PuO2 powder synthesized using the freeze-granulation route

Sintering investigations of a UO₂-PuO₂ powder synthesized using the freeze-granulation route

Marion Le Guellec, Florent Lebreton, Laure Ramond, Abibatou Ndiaye, Thierry Gervais, Guillaume Bernard-Granger

Abstract

Sintering investigations of a UO₂-PuO₂ powder, integrating 11 wt% of PuO₂ and synthesized by freeze-granulation, were completed at temperatures up to 1700°C, in an atmosphere of Ar/4 vol% H₂ and 1200 vpm H₂O. Analyzing the “grain size versus relative density” trajectory enabled to propose that densification was controlled by volume diffusion and grain growth by the grain boundaries. An activation energy around 630 kJ/mol was obtained for densification, which was close to the value reported for volume diffusion of plutonium cations in U_1-xPu_xO₂ polycrystals. The sintered microstructure appeared homogeneous regarding the plutonium and uranium cations distribution.

Keywords

Sintering, Ceramics, Oxides, Microstructure, MOX