The Thermal Diffusivity and Lattice Parameter measurements in a (U, Ce)O2 Mixed Oxide Sintered Pellet as a Function of the Ce Content

Abstract

(U, Ce)O2 pellets were fabricated as a function of the Ce content (0, 5, 10, 15, 20 wt%), and the thermal diffusivities of these samples were measured from R.T. to 1673 K using a laser flash method. And the lattice parameter was also examined using an X-ray diffractometry (XRD) to investigate the theoretical density of each composition and to compare it with various results using a 95%-normalization. The measured lattice parameter gradually decreased with increasing Ce content, and its tendency followed Vegard`s law. That is to say, in the range of this experiment, it was shown that most of the cerium oxides were dissolved in the UO2 matrix. And the calculated theoretical density decreased, as well. According to the increment of the Ce content, i.e., the amount of dissolved oxide in the UO2 matrix, a 95%-normalized thermal diffusivity degradation was resulted. But, in the cases of a 15 and 20wt% Ce content, they were dissimilar to the results of a lower content, especially above 1000 K.