b'Thermodynamic Evaluation of U 3 Si 2Hydride ReactionsPrincipal Investigator: Aditya P. Shivprasad, LANL Team Members/Collaborators: Joshua T. White and Joseph R. Wermer (LANL)This project has made great strides in understanding the degradation of U 3 Si 2during exposure to hydrogen and the methodology used here could be used to study the degradation of other high uranium-density compounds and composite systems.U 3 Si 2is a promising, high- Project Descriptionuranium-density fuelUpon exposure to steam and because of its good thermalsimulated pressurized water reactor properties and performance during(PWR) conditions, U 3 Si 2fuel irradiation and has been consideredhas been shown to significantly as a potential replacement fordegrade. In steam at temperatures UO 2in commercial light waterabove approximately 350 C reactors. Despite these advantages,and atmospheric pressure, rapid limitations are observed whenoxidation and pulverization have the coolant comes in contact withbeen observed. However, no the fuel, e.g., breach of cladding,significant structural degradation resulting in degradation of the fuel.was apparent during exposure at Research focused on continuinglower temperatures. Examination of work from fiscal year (FY)18 thatthe post-corrosion microstructure studied hydrogen absorption ofof U 3 Si 2exposed to steam at low U 3 Si 2and relating this performancetemperatures showed similarities to previous steam testing. Hydrogenwith uranium metal under similar absorption was performed using aconditions. Because uranium metal Sieverts apparatus at temperaturesin steam is known to hydride at low from 250 to 500 C and pressurestemperatures and oxidize at high up to 1.5 atm of hydrogen.50 2019|AFC ACCOMPLISHMENTS'