Sensitivity coefficients for fast reactor core analysis

Sensitivity coefficients of neutronics characteristics with respect to cross section changes are very useful for the evaluation of the effect of nuclear data change, the cross section adjustment and the uncertainty evaluation. In the analysis of fast reactors, the sensitivity coefficients have to be calculated in multi energy groups to consider the cross section behavior in resonance energy range and fast energy range. Therefore, it is desirable to develop a method to extend and/or condense energy group structures in calculating sensitivity coefficients. In this paper, a method is developed to extend and/or condense energy groups, and the usefulness of the method is shown by numerical calculations in a fast reactor