Preliminary Results from Post-Irradiation Heating Tests on Low- and High Temperature AGR-5/6/7 Fuel Compacts

Abstract

Four uranium oxycarbide (UCO) tristructural isotropic (TRISO) coated particle fuel compacts from the US Advanced Gas Reactor (AGR) Fuel Development and Qualification Program's final qualification campaign were subjected to post irradiation safety tests. The Fuel Accident Condition Simulator (FACS) furnace at Idaho National Laboratory was used to heat the fuel to 1600°C for 300 hours. Fission gases and condensable fission products released from the fuel during the tests were measured to assess the fuel performance. This assessment included preliminary determinations of the TRISO coating integrity and the retention or release of key fission products. These samples had burnups ranging from 9.2 to 15.2% fissions per initial metal atom (FIMA), along with time-average-volume-average (TAVA) irradiation temperatures of between 711 and 1361°C. For compacts with TAVA temperatures of less than 920°C, only small quantities of Cs were detected, indicating that no SiC layer had completely failed in any of the particles. The compact irradiated at 1361°C appears to have experienced one SiC failure at >200 hours at 1600°C. Releases of other key fission products were compared among the AGR-5/6/7 compacts tested here, as well as against other AGR fuel tested previously.