Methods for Calculating Neutron Transfer Probabilities Between Assemblies

We explore two methods for determining the probability that a neutron, upon leaking, will transfer from one spherical assembly to another, namely, the view factor method (VFM) and the sphere point picking method (SPPM). The VFM is an approximate analytical method that assumes the neutron is leaking from a point source, and therefore, has applicability limitations. The SPPM is a purely Monte Carlo method that samples a location on the surface of a sphere as well as a trajectory leading away from said system to then determine if the neutron streams into another assembly. Numerical results from the two methods are contrasted, and the relative merits of each method discussed.