b'Finally, working with the irreplaceableWith many successes, significant stockpile of legacy EBR-II irradiatedchallenges were also encountered such materials has required significantas developing new understanding of effort to recover test specimens,the TREAT safety case for complex pertinent data and records, andand energetic power shapes in TREAT, develop an approach to obtain detailedwhich required more analysis itera-neutronic characterization of thetions than were anticipated. The logis-as-irradiated state of the fuel pins.tics of the capsule assembly required Working with Idaho State Universityintense experimental validation of and their developed EBR-II bench- solutions to maintain sodium within mark model, experiment irradiationthe capsule where required. Transfer-conditions were generated andring legacy irradiated fast reactor fuels passed to a depletion code to createbetween facilities required significant best-estimate predictions for materiallogistical coordination and firsts in isotopic inventories. These results werefacilities not accustomed to handling crucial to calculating energy couplingMOX. Significant hurdles remain to within the TREAT reactor to ensurecomplete the ARES work requiring energy targets are achieved and will beunique logistics such as transferring verified via experimental methods inirradiated materials between facili-the next year on the MOX pins. Figureties while ensuring facility material 3 shows an example of calculatedinventory limits remain within limits, axial distribution of U235 in a MOXaccomplishing extensive characteriza-pin, a photo showing the recoveredtion of specimens before and after the MOX pin, and a historical neutronTREAT experiments, and development radiograph of the MOX pins post- of THOR handling capabilities in HFEF irradiation in EBR-II. to load irradiated test specimens.126 2021|AFC ACCOMPLISHMENTS'