Implementation of resonance upscattering treatment in FRENDY nuclear data processing system

Yamamoto, Akio*; Endo, Tomohiro*; Chiba, Go*; Tada, Kenichi

Nuclear Science and Engineering, 196(11), p.1267 - 1279, 2022/11

https://doi.org/10.1080/00295639.2022.2087833

The resonance upscattering effect (the thermal agitation effect) is incorporated in the generation capability of multi-group neutron cross sections of the FRENDY nuclear data processing system. The resonance upscattering effect is considered by (1) the variation of self-shielding factors (effective cross sections) due to the change in ultra-fine group spectrum and (2) the variation of group-to-group elastic scattering cross sections. In the verification calculations, impacts on the ultra-fine group spectrum, effective cross sections, and neutronics characteristics (the Doppler effect) are confirmed. The effect of energy group structure and the treatments of resonance upscattering on the Doppler effect through the variation of effective cross sections and the elastic scattering matrix are studied. The results indicate that the FRENDY can provide appropriate multi-group cross sections considering the resonance upscattering effect.