Research of Global-Local Resonance Self-Shielding Calculation Method Based on NECP-X

To meet the challenges faced in high-fidelity resonance self-shielding calculations,the global-local self-shielding calculation method is proposed.The resonance self-shielding and correlated effects are classified into global and local effects.The global effects are weak or independent of energy,while the local effects are strong.Therefore,the resonance self-shielding calculation is split into global,coupling and local calculations.Coarse model is built for global calculation and the neutron current method is employed to compute Dancoff correction factors,where the global effects are considered.The coupling calculation is based on preservation of the Dancoff correction factors and the equivalent 1-D models of the fuel rods are obtained.The pseudo-resonant-nuclide subgroup method is employed to perform the local calculation to treat the local effects.This method is realized in NECP-X.The numerical results show that the efficiency of this method is increased by one order of magnitude compared with the conventional method.Besides,the precision of infinite medium multiplication factor is increased by 100~300 pcm.