A Technique for Accounting for Multigroup Cross-Section Interdependence in Sensitivity Calculations

In this paper a new technique for accounting for multigroup cross section interdependence in sensitivity calculations is proposed and numerically investigated. In this technique the so-called implicit sensitivities representing multigroup cross-section interdependence are calculated through subgroup parameters. The technique turns out to be easy to implement in existing multigroup cross-section preparation codes and can cover both the homogeneous media and the heterogeneous media conventionally considered in such codes. This technique allows further extensions to cover arbitrary heterogeneous structures. The Monte Carlo technique of computing conventional sensitivities of keff to multigroup cross sections used in this paper is also described.