b'Figure 2. Neutron flux spectra comparison within BR2 with and without thermal neutron filteringhighest achievable fast neutron flux.are primarily focused on fuel mate-The second concept modeled each ofrial performance but include more the seven pins independently encapsu- moderator within the BR2 element lated and utilized cladding to capsuleresulting in relatively lower fast-to-gas gaps to increase critical fuelthermal ratios (~50-100). Continued temperatures relative to ATR coolantrefinement of detailed mechanical temperature.This approach appeareddesign and thermal hydraulic condi-to be well suited for achieving thetions was noted as primary area for desired temperatures and gradientsmaturation of the ARCTIC concept in for irradiations whose data objectivesany future development efforts.2021|AFC ACCOMPLISHMENTS 131'