UN-UB[formula omitted] Composite fuel material; improved water tolerance with integral burnable absorber

Abstract

As part of a scoping study to investigate the initial feasibility of UN-UB2 composites, pellets of 5, 25 and 50% UB2 within UN were produced via Spark Plasma Sintering alongside a high density UN material. The pellets were seen to have a well-formed and dense microstructure which did not appear to change after annealing for 24 hours at 1273 K, which consisted of UN, UB2 and a UBN phase, with an additional UB0.1N0.9 phase suggested via EBSD. Steam exposure in an STA demonstrated that an increase in reaction onset temperature of approximately 150 K can be achieved via the addition of 25% UB2, and an increase of 120 K in onset temperature was evident in pellets containing only 5% UB2. High density UN was tested alongside these composites and behaved similarly, but microstructural examination of composites post-oxidation suggest that the oxidation rate is retarded in porous regions in addition to highly dense regions.