2017 | AFC ACCOMPLISHMENTS 136 Table 1. Table showing the foil thickness and contribution to the overall zirconium percentage used for the first series of tests. Despite the robustness of metal fuels, they are susceptible to fuel cladding chemical interactions (FCCI). FCCI is caused by fission product rare earth elements interacting with the iron based cladding.This reaction effectively reduces the cladding thickness, which is major limiting factor for high burnup metal fuels. If this FCCI could be mitigated, possible burnup limits could also be increased.A method of mitigating FCCI in metallic fuels is to incorporate an integral FCCI barrier material, such as zirconium, between the fuel and cladding.The initial feasibility of integral fuel FCCI barrier was shown previously during the Integral Fast Reactor program. However, during post irradiation examination, it was seen that as the fuel swelled, the sheath was split, and the fuel extruded out. In areas where the fuel was still contained in the sheath, there was no evidence of FCCI.A possible strategy to accommodate fuel swelling is to incorporate a foil wrapped around the fuel with an overlapping section that corresponds to the amount the fuel will swell.As the fuel swells, the foil will unwrap while maintaining complete coverage of the fuel. FCCI Barrier Development Principal Investigator: Randall Fielding Collaborator: Laura Sudderth Sample ID Charge Mass Wt% Zr Foil Thickness Foil wt% Pin Length (mm) F7 11.8 10.0 0.0005 0.54 49.5 F8 11.82 9.64 0.005 6.52 53.3 F9 14.76 9.98 0.001 1.26 63.5 F10 14.736 9.96 0.002 2.44 63.5