b'Oxidation of CeriumCerium nitride, a non-radioactive surrogate for actinide Nitride under Irradiation nitrides, oxidizes at very low oxygen partial pressures.C erium nitride, a uranium nitride fuel surrogate material, was successfully sintered within tens of seconds using a pressureless fast heating technique. The as-sintered pellets have a relative density of 96% with uniform grain size of 1020 m. Cerium nitride remained stoichiometrically stable during the fast sintering. However, cerium nitride ceramics are very sensitive to air. Transmission PROJECT NUMBER:electron microscopy characterization of lamellas prepared from the as-sintered 21P1062-019 cerium nitride pellets shows that the lamella was fully oxidized and became cerium dioxide. Ab initio density functional theory was used to calculate the thermodynamic TOTAL APPROVED AMOUNT:driving forces for the oxidation of metal nitrides. The calculated large values indicate $125,000 over 1 year that the oxidation of metal nitrides is highly favored and can occur even at very low PRINCIPAL INVESTIGATOR:oxygen partial pressures.Lingfeng He TALENT PIPELINE:CO-INVESTIGATORS: Logan Joyce, student at Purdue UniversityChao Jiang, INL PRESENTATIONS:Yi Xie, Purdue University Joyce, L., Y. Xie, Fabrication of CeN (UN fuel surrogate) using pressureless fast heating COLLABORATOR: system, 2022 ANS Annual Meeting, Jun. 1216, 2022.Texas A&M University He, L., K. K. Bawane, T. Yao, P. Xiu, C. Jiang, M. Khafizov, M. Jin, Y. Xie, L. Shao, Microstructural Evolution in Ceramic Nuclear Fuels and their Surrogates under Irradiation, Materials Science & Technology technical meeting (MS&T 22), Oct. 2022 (Invited talk).Characterization of cerium nitride oxidation. (a) Scanning transmission electron microscopy (STEM) image, (b)-(d) energy dispersive x-ray spectroscopy, (e) selected area electron diffraction pattern, and (f) atomic-resolution STEM image of a lift-out lamella from an as-sintered cerium nitride pellet showing that cerium nitride was fully oxidized to cerium dioxide (CeO).43'