The Advanced Gas Reactor (AGR) program is in the process of qualifying tristructural isotropic (TRISO)-coated uranium carbide/uranium oxide (UCO) fuel for use in high-temperature gas-cooled reactors (HTGRs) in the United States. The second AGR irradiation (AGR-2) started in the Advanced Test Reactor (ATR) in June 2010 and was completed in October 2013. The first AGR irradiation (AGR-1) tested fuel produced on laboratory scale equipment, but the AGR-2 TRISO-coated fuel particles were produced on an industrial scale and then overcoated and compacted into cylindrical compacts using laboratory-scale processes. Both UCO and UO2 fuels were irradiated in AGR-2 so that their performance could be compared. The UCO fuel was in Capsules 2, 5, and 6, and the UO2 fuel was in Capsule 3. (Capsules 1 and 4 were French and South African fuel, respectively. These fuels will not be discussed.) UCO burnups ranged from 7.3 to 13.2 % fissions per initial metal atom (FIMA), and compact time-averaged, volume-averaged (TAVA) irradiation temperatures ranged from about 1000°C to 1300°C. UO2 compact burnups ranged from 9.0 to 10.7 % FIMA, and compact TAVA temperatures ranged from about 1000 to 1060°C.
