b'2.2 LWR CORE MATERIALSInitial Deployment of MiniFuel in the Removable Beryllium ReflectorPrincipal Investigator: Jacob GortonTeam Members/Collaborators: Annabelle Le Coq, Zane Wallen, Christian Petrie, Joshua White, Nathan Capps, Kory LintonT he MiniFuel experimentaldesign calculations for the initial platform at ORNL has beenexperiment containing Cr-doped used for separate-effectsUO 2fuel samples, and insertion of nuclear fuel irradiations in thethe first RB MiniFuel experiment High Flux Isotope Reactor (HFIR)into HFIR on July 5, 2023.since 2017 [1]. The initial capability was qualified for deployment inProject Description:HFIRs vertical experiment facilitiesThe overarching objective of the RB (VXF), located roughly 20 cm fromMiniFuel irradiation capability is the outermost fuel element, whichto study critical fuel performance enabled irradiations with fuel spec- phenomena at high temperatures imen temperatures typically rangingand burnups. Cr-doped UO 2was from 500C to ~700C and up toused in the first RB MiniFuel experi-~1000C in some cases [2]. MiniFuelment, and the primary objective experiments conducted in HFIRswas to investigate the impact of Cr removable beryllium (RB) reflectorcontent and UO 2grain size on FGR. would enable fuel temperaturesTwo UO 2grain sizes and two Cr 1000C to be achieved with fasterconcentrations (750 ppm and 2500 fuel specimen burnup accumulationppm) were considered for the fuel compared with VXF experimentsspecimens. The experiment was because of the closer proximitydesigned to provide time-average, to the driver fuel elements. Thesevolume-average (TAVA) fuel temper-conditions are better suited toatures between 1075C and 1100C studying critical fuel performancefor each of the 12 fuel specimens phenomena, such as fission gasincluded in the experiment. Desired release (FGR). Design changes to thefuel temperatures are met by sizing MiniFuel experimental architecturethe outer diameter (OD) of each to enable deployment in the RBsubcapsule (thus changing the reflector were documented in agas gap between each subcapsule fiscal year (FY) 2021 AFC milestoneand the target inner wall) and by report [3]. This report summarizesselecting the target fill gas mixture. the FY 2023 accomplishmentsFigure 1 shows a schematic of the pertaining to RB MiniFuel, whichRB MiniFuel platform along with include safety qualifying the experi- component designations. The ment for HFIR insertion, executingspecimens in one MiniFuel target 44 2023|AFC ACCOMPLISHMENTS'