On the Capability of SMORES to Account for Self-Shielding in Search for Maximum keff

This study investigates the capability of SMORES – a new prototypic analysis sequence of SCALE -5, to identify the maximum keff composition of 5% enriched uranium – water systems having fixed fuel mass. The effects of resonance self -shielding are accounted for. Simplified one-dimensional slab geometry systems are considered. It is found that SMORES is capable of identifying nearly optimal lumped composition of cores fueled with low enriched fuel the keff of which can increase by increasing the resonance self shielding. The near optimal composition can be identified starting from either homogeneous or non -optimally lumped composition. The deviation of the converged lumped composition from the absolutely optimal depends on the amplitude of density change per iteration in addition to the initial composition. Large density changes per iteration may impair convergence and result in far from optimal lumped composition.