A NEW SELF-SHIELDING METHOD BASED ON A DETAILED CROSS-SECTION REPRESENTATION IN THE RESOLVED ENERGY DOMAIN

The calculation of a dilution cross section a, is the most important s tep in the self-shielding formalism based on the equivalence principle . If a dilution cross section that accurately characterizes the physic al situation can be calculated it can then be used for calculating the effective resonance integrals and obtaining accurate self-shielded cr oss sections. A new technique for the calculation of equivalent cross sections based on the formalism of Riemann integration in the resolved energy domain is proposed. This new method is compared to the general ized Stamm'ler method which is also based on an equivalence principle, for a two-region cylindrical cell and for a small pressurized water r eactor assembly in two dimensions. The accuracy of each computing appr oach is obtained using reference results obtained from a fine-group sl owing-down code named CESCOL. It is shown that the proposed method lea ds to slightly better performance than the generalized Stamm'ler appro ach.