Speaker
Description
Accurately describing the scattering behavior of thermal neutrons can guarantee the accuracy of neutronics calculation. The thermal neutron scattering law (TSL) data is used to describe the scattering property of a materials. In this work, some efforts have been made to improve the accuracy of TSL data. The anisotropic displacement parameters method is used to remove the cubic approximation in the traditional method, and the one-phonon correction method is used to consider the distinct scattering term of one-phonon ignored by the incoherent approximation method. The methods mentioned above have been implemented into sab_calc, a module developed for TSL calculation in the nuclear data processing code NECP-Atlas. Furthermore, the coherent and incoherent elastic scattering can be considered simultaneously in sab_calc. The influence of the improved method on the accuracy of neutronics calculation is quantitatively analyzed based on the criticality benchmarks. The numerical results show that the TSL data, scattering cross section and total cross section calculated by the improved method are more consistent with the experimental values, and the calculation accuracy of reactor reactivity in the benchmarks is significantly improved. Simultaneously considering the coherent and incoherent elastic scattering has tens of pcm effects on keff of the analyzed TRIGA reactors.