An analytical multigroup benchmark for (n, γ) and (n, n′, γ) verification of diffusion theory algorithms

► Coupled neutron and gamma transport is considered in the multigroup diffusion approximation. ► The model accommodates fission, up- and down-scattering and common neutron-gamma interactions. ► The exact solution to the diffusion equation in a heterogeneous media of any number of regions is found. ► The solution is shown to parallel the one-group case in a homogeneous medium. ► The discussion concludes with a heterogeneous, 2 fuel-plate 93.2% enriched reactor fuel benchmark demonstration.