Resonance Self-Shielding near Zone Interfaces

A practical methodology is developed to treat the resonance self-shielding transition near zone interfaces. Based on the narrow resonance approximation, a space- and energy-dependent selfshielding factor for a single interface system is derived from the integral transport theory. Using the Wigner rational approximation, the self-shielding factor for a fine region near a zone interface isfac-torized into a linear combination of individual homogeneous and heterogeneous self-shielding factors. The method has been implemented in a widely used cross-section processing code that is based on the Bondarenko f-factor method. The result of the analysis was applied to a fast reactor blanket mock-up to improve the calculations near a converter-blanket interface. Comparisons of the calculation with ²³⁸U capture experimental data measured in the Purdue Fast Breeder Blanket Facility are also discussed.