NECP-Atlas中共振弹性散射核处理模块的开发与验证

The thermal motion of target nuclei and the resonance elastic scattering have been considered in the generation of multi-group cross sections and scattering matrices. Firstly, the resonance elastic scattering kernel (RESK) formulations for anisotropic scattering up to any Legendre order has been adopted to calculate the exact Doppler broadened energy transfer kernels. A semi-analytical integration method is applied to perform the RESK calculations. Combining with the RESK calculation, a linearization algorithm is proposed to generate the RESK interpolation tables. The RESK data can be interpolated precisely based on the RESK interpolation tables to reduce the calculation burden. Secondly, a neutron slowing-down equation solver is developed based on the RESK instead of the conventional asymptotic scattering kernel. The effect of neutron up-scattering on the neutron energy spectrum can be exactly taken into account by the solver. More precise multi-group cross sections are obtained when more precise energy spectrum are adopted in the group collapsing procedures. All the methods mentioned above have been implemented into the nuclear data processing code called NECP-Atlas. Numerical results show that the proposed methods are capable of producing accurate multi-group cross sections for downstream calculation; Compared with the multi-group cross sections and scattering matrices generated by the conventional methods, the fuel Doppler coefficients and eigenvalues calculated by the deterministic codes change greatly when the up-scattering effect is considered.