Group Transfer Matrices and Their Relation to Basic Cross Section Data

The in-scattering sources in the group-Legendre expansion of the Boltzmann equation can be classified by four-index sources, four-index cross sections, or four-index kernels, depending on the type of multigroup approximation used. These four-index transfer elements are related to basic cross-section data through a general four-way logic which applies to narrow and wide groups alike, to heavy and light scatterers alike, and to elastic and single-level inelastic scattering alike. As an application of the logic, the effect of inelastic energy-angle correlation on the calculation of some reactor parameters is demonstrated.