Semi-analytical partial n'th collision source correction for multi-dimensional S(N) photon transport calculations

Abstract

A Semi-Analytical Partial n'th Collision Source (SAPNCS) method that is fully compatible with the standard three-dimensional SN has been developed. The method generates a matrix operator that calculates scattering source for particles that have suffered n collisions in a selected number of mesh cells. Adopting this scattering source as distributed source, the standard three-dimensional SN method then calculates the remaining contribution to the flux. The sum of uncollided and collided fluxes yields total flux. Several tests for photon transport calculation in x-y-z geometry have been fully conducted and the illustrative results demonstrating the capability of the method to mitigate and eliminate the observable ray effects are presented.