Fabrication of Neutron-photon Coupling Multi-group Cross-section Library Based on Monte Carlo Method

Deterministic calculation codes have the advantage of high calculation efficiency and are suitable for radiation shielding calculation of nuclear reactors, but its accuracy mainly depends on the precision of multi-group cross-section library. Different types of reactors have varying energy spectra, and the currently available general multi-group cross-section libraries cannot ensure calculation accuracy across different reactor types. This study improves the method for generating neutron-photon coupled multi-group cross-section libraries based on the Monte Carlo code OpenMC. A new feature for counting photon production cross-sections resulting from neutron reactions has been added. The photon sources produced by atomic relaxation, bremsstrahlung and positron and electron annihilation are considered and treated by scattering. To validate the applicability of this method, the OECD/NEA fast reactor benchmark, the Savannah thermal reactor benchmark, and the HBR-2 shielding benchmark are utilized for generating the neutron-photon coupled multi-group cross-sections. The produced multi-group cross-section libraries are provided to the deterministic code DORT for calculations. The results are compared with those from OpenMC. For both fast and thermal reactor models, the results using the newly developed multi-group cross-section libraries show good agreement with OpenMC results and outperformed those obtained using the Bugle96 library.