Simulation of a sodium fast core: Effect of B1 leakage models on group constant generation

It is shown that, even if a fissile assembly can be calculated without leakage, the heterogeneous TIBERE model is best suited for “cluster calculations” (a fertile or reflector assembly surrounded by fuel assemblies). Moreover, the homogeneous B1 model should be avoided in such calculations since it is not able to handle streaming effects between the different assemblies.