Sintering of MOX Fuel Pellets in Hydrogenated Argon Atmospheres
Kaythleen Torrente, Christelle Duguay, Franck Doreau, Florent Lebreton, Guillaume Bernard‐GrangerABSTRACT
The sintering behavior of MOX fuel pellets containing 11 and 26 mol% Pu/(U+Pu), prepared by direct dry co‐milling of UO 2 and PuO 2 raw powders, was investigated under humidified Ar/4.3 vol% H 2 atmospheres (relative humidity level set at 100 and 1200 vpm). Sintering maps (grain size change as a function of relative density) were plotted, and the apparent activation energies for densification were calculated using the Constant Rates of Heating method. The microstructures of various sintered pellets with a relative density of approximately 98%–99% were characterized with regard to grain size. Nonparametric statistical tests were performed at the 5% threshold to determine whether there were statistically significant differences between the number‐grain size distributions related to plutonium content, relative humidity level of the sintering atmosphere, and the area analyzed (periphery versus center of the pellets).