Six homogeneous and heterogeneous core configurations with different fuel pin diameters and different degrees of neutronic coupling have been analyzed. All designs were based on the same design assumptions and constraints. Homogeneous and heterogeneous designs were evaluated with respect to fissile inventory, flux and power distribution, burnup, breeding ratio and doubling times, sodium void reactivity, Doppler coefficient, control rod worth, and transient response. The sensitivity of breeding performance to different fuel life criteria was determined.