b'2.3 LWR IRRADIATION TESTINGATF Rodlet Irradiation in ATR (ATF-2C)Principal Investigator: David KamermanTeam Members/Collaborators: Brian Durtschi, Travis-Laboossiere-Hickman, Matilda A. Aberg Lindell, Richard SkiftonThe ATF-2C experimentA ccident Tolerant Fueldevelopment of new fuels for light (ATF)-2C is the latest itera- water reactors relies heavily on this tion of the Advanced Fuelscapability. The ATF-2 experiment representing the stateCampaigns flagship irradiation teststarted in 2018 and successfully of the art in irradiationlocated in the center flux trap ofcompleted 7 cycles of irradiation on test sophisticationthe Advanced Test Reactor (ATR).over 40 different test pins comprised completed assemblyATF-2C provides a fully prototypic,of mostly evolutionary chrome and began irradiationflowing, pressurized water testcoated zirconium alloy cladding in 2023. environment via the Loop-2Aconcepts. In 2021 and 2022, the independent water loop. ATF-2CATR underwent a massive core continues the irradiation of chromeinternal change out. During that coated cladding from the previoustime the ATF-2 experiment was ATF-2B experiment and is the firstredesigned and expanded to include ATF test to include novel SiC-SiCrevolutionary ATF concepts such cladding materials. The pinnacle ofas novel silicon carbide (SiC)-SiC the test is the irradiation of 6 longercladding materials and the use (55cm) fuel pins, four of whichof in-situ instrumentation.contain in-situ instrumentation.The irradiation of SiC-SiC cladding Two of the pins contain centerlinematerials started with empty clad-thermocouples (TCs) and two ofding tubes and will next include the the pins contain pressure bellowsirradiation of cladding tubes with with linear variable differentialinert molybdenum gamma heaters transducer (LVDT) assemblies forreplicating fuel pellets in cycle measuring plenum pressure. The173A. Full fueled irradiations of irradiation began with ATR cycleSiC-SiC cladding will then begin in 171A on the 26th of April 2023 andcycle 175A. The long, instrumented is planned to be irradiated for a totalfuel pins are part of a collaboration of 4 ATR cycles (60 effective fullwith the Japan Atomic Energy power days per cycle) concluding inAgency (JAEA) and Mitsubishi September 2024. Heavy Industries, where chrome Project Description:coated zirconium alloy cladding With the closure of the Haldenprovided by Mitsubishi are tested in nuclear reactor in Norway inconjunction with the in-situ sensors. 2018, Idaho National LaboratorysTwo of the instrumented pins will Loop-2A in the center flux trap ofcontain type N TCs. These pins will ATR is the only fully prototypicuse Conax-type compression seals pressurized water loop available forat the top to form a seal with the civilian nuclear fuels and materialsTC. These compression seals have testing in the western world. Thebeen fabricated from Zircalloy-4 to 70 2023|AFC ACCOMPLISHMENTS'