Boundary Condition Perturbation Theory for Use in Spatial Homogenization Methods

An expression is developed in diffusion theory for estimating the first-order change in a ratio of linear functionals due to a perturbation in the current-to-flux ratio boundary condition of a system. One numerical example is given. Additionally, it is shown that the perturbation formalism may be used in the spatial homogenization process to account for interassembly effects such as gross flux tilts and spectral effects caused by neighboring assemblies in the reactor core.