Diffusion of Intermediate Energy Neutrons into a Thick Resonance Absorber

The problem considered is the calculation of the diffusion of intermediate energy neutrons from a large moderated region into a thick resonance absorber. This is of interest for a coupled fast-thermal reactor. Boundary conditions at the interface between the two regions appropriate for a P − 1 calculation in the moderator are investigated. The transport approximation in the moderator is found to give good results even for hydrogenous moderator.