Generalized Bilinear Weighting for Multigroup Cross-Section Collapsing

A new multigroup cross-section collapsing procedure is described in the framework of the generalized perturbation theory. Numerical examples suggest its use, in addition to the standard linear flux and bilinear real-flux/adjoint-flwc weighting procedures, when reactivity coefficients, such as the sodium void coefficient, are to be preserved in a few-group model.