b'In an effort to avoid powder contamination and agglomeration, as seen in the in-house CeO 2powder, commercial CeO 2nanopowder was used to produce sim HBS via FS. As shown in Figure 2, the pellets produced by FS retained an average grain size of 0.4 m near the surface of the pellet, and of about 1 m, at the center of the pellet. This heterogeneity was expected due to the temperature gradient during FS. The average open porosity of the FS pellet was 10.5 vol.% and the close porosity was 1.9 vol.%. A conventionally sintered (CS) pellet, on the other hand, had an average grain size of 2.1 m distributed homogeneously across the pellet and an open porosity of 1 vol.% and closed porosity of 7.5 vol.%.The capability to fabricate sim-HBS on ceramic materials was established at LANL. The efforts described here showed that FS can deliver sim HBS of ceramic materials such as CeO 2and UO 2 , although further powder optimization is necessary for the latter. Therefore, the next steps are to improve the in-house synthesis of UO 2nanopowder and to start analyzing the thermophysical and mechanical properties of the resulting sim HBS. It is expected that this technology can help in separate effects testing efforts of HBS and that it will reduce the difficulties Figure 2. Grain size (GS) distributionassociated with experiments done on across flash sintered CeO 2pellet madeheavily irradiate materials.with commercial nanopowder. Insert indicating average GS in conventional sintered (CS) sample.24 2021|AFC ACCOMPLISHMENTS'