b'and instrumentation installationthen replaced with the moderator at the Materials Science Laboratory.assemblies. The moderator During this time, the fresh fuel testassemblies formed the ten-inch pin was fabricated and assembledopening needed to support the by the Materials and Fuels Complexnew Big-BUSTER. Big-BUSTER and (MFC) fuel fabrication assemblyBig-BUSTER NED was designed by team at the Advanced Fuel Fabrica- the NF&M design engineering team. tion (AFF) facility with a centerlineThe Big-BUSTER was fabricated at thermocouple. The fuel fabrica- Nu-Tech Precision Metals in Canada. tion team completed the capsuleThe Big-BUSTER NED was fabricated subassembly at AFF by welding theat the ATR machine shop. Both the thermocouple into the fuel pin, fuelBig-BUSTER and Big-BUSTER NED pin installation into the capsule,have been used in TREAT to support and closing the capsule completingthe first TWIST commissioning test, a level two milestone ahead ofcompleting the large experiment schedule in August 2023 (Figurecapability that will enable loop-scale 1). The TWIST capsule was sent totesting in TREAT (Figure 2).TREAT operations team where theyPreparations for testing high burnup added water and leak checked thefuel from the Byron Nuclear Gener-capsule prior to placing into theating Station are also underway with TREAT core. TREAT inserted thecompletion of preliminary design LOC-C-1 into the TREAT core in Big- of TWIST experiments, HERA-HBu BUSTER and completed the powerand LOCA-HBu. This design will be calibration transient. The data fromthe workhorse for the previously this experiment will be analyzed toirradiated RIA and LOCA testing in validate predicated heating rates forthe future.the specimen in the TWIST device and ensure future experiment power targets are hit.Large experiment capability was put into place by completing several plant modifications. The new retro fit shield plug was designed by the TREAT design team and fabricated at the MFC machine shop. The retro fit shield plug was replaced by TREAT operations personnel completing the first step towards the large experiment capability. The Moderator assemblies were designed by the TREAT design team and fabricated at the Advanced Test Reactor (ATR) machine shop and the MFC machine shop. To install the four moderator segments nine fuel elements from the center of the TREAT reactor core were removed 2023|AFC ACCOMPLISHMENTS 203'