2018 | AFC ACCOMPLISHMENTS 158 Figure 1. Transverse cross section of AFC-3D R1 (U-10Zr, 55% smear density, annular, He bonded, 4.3 atom % burnup). This fuel has performed well to moderate burnup and shows no sign of fuel cladding chemical interaction which demonstrates the need to carefully control the dimensions of fuel when using helium bonding. The AFC-3C,AFC-3D, and AFC-4A capsule irradiations were irradiated at the Idaho National Laboratory (INL) Advanced Test Reactor (ATR) and underwent postirradiaton examination (PIE) recently.These irradiations were planned to test several different fast reactor fuels that could be used to facilitate ultra-high burnup applications in sodium fast reactors (SFRs). Several different alloys, fuel geometries, bonding materials, and the use of additives were tested in ferritic-martensitic HT-9 cladding. Project Description: This research facilitates the development of fuel technologies for different missions that can be used in an SFR or other similar advanced reactor concepts. One of the technologies tested is He bonding of metallic fuel to cladding. If this technology can be successfully demonstrated it could be used to possibly eliminate sodium bonding of the fuel to the cladding.This is an important enabling technology that simplifies the final disposal of fuel used in a “once-through fuel cycle” advanced reactor.These tests also investigated the irradiation effect of adding lanthanide gettering additives.This technology may enable high burnup fuel operation beyond historically established limits by preventing fuel cladding chemical interaction embrittlement of the cladding.The final major technology investigated is the effectiveness of utilizing alternative alloys that simplify the behavior of the fuel under irradiation.These alloys may be easier to model using advanced modeling and simulations tools.Additionally testing alternative alloys helps to highlight different physical phenomena in the fuel, creating further opportunities to refine and enhance modeling tools. Observations of Irradiated Annular and Low Smear Density Metallic Fuels Principal Investigator: Jason M. Harp Collaborators: Luca Capriotti, Fabiola Cappia Accomplishments: TheAFC-3C,AFC-3D, andAFC-4A experiment took various different U-Mo, U-Zr, U-Pd-Zr, U-Mo-Ti-Zr, and U-Mo-Ti-Zr-Pd alloys to burnups of 2.1% to 4.5% FIMA (fissions per initial heavy metal atoms) and fission densities of 6.13x1020 to 1.27x1021 fissions / cm3 .These alloys were evaluated against