Verification Analysis Of Lead-Bismuth Fast Reactor Shielding Library

Accurate radiation shielding calculations are crucial for the design,operation,and personnel safety of lead-bismuth fast reactors.The discrete ordinates method(SN)is one of the classical deterministic transport solution methods.The SN method uses group-wise approximation of the discrete energy variable,and the accuracy of the multigroup cross-section data depends on the precision of the evaluated nuclear data and the approximation errors introduced in the multigrouping process.The validation of multigroup cross-section data is an important aspect in ensuring the reliability of shielding calculation results.In this study,the MATXS-LFR multigroup cross-section library was developed based on the ENDF/B-Ⅶ.1 evaluation database.Corresponding MATXS multigroup cross-section libraries were also developed for important isotopes such as Pb and Bi in the ROSFOND-2010,JEFF-3.3,and CENDL-3.2 nuclear evaluation databases.Structural and coolant materials were tested using international benchmark integral experiments for single nuclides.The main factors causing neutron leakage spectrum results and experimental deviations in lead and bismuth isotopes are analyzed,and the reaction types that had the largest perturbation on the leakage spectrum results were studied through sensitivity analysis.The cross-section reactions that could potentially have problems were identified by comparison with different evaluation libraries.The multigroup cross-section library was validated and analyzed for its application in LFR using a fast spectrum experimental apparatus and a lead-bismuth fast reactor as the computational model.The numerical results show that in the benchmark validation of lead,the secondary particle angle distribution in elastic scattering is the main cause of calculation differences between evaluation databases above 2 MeV.The division of the 199 neutron energy group structure at 0.5 MeV causes significant differences in the total cross-section within the energy group,resulting in deviations between the neutron leakage spectrum and experimental values.For bismuth,non-elastic level scattering cross-sections primarily affect the 6-12 MeV energy range,and the non-elastic level scattering cross-section calculation results of JEFF-3.3 are in the best agreement with experimental values.However,there are significant differences between the numerical results and experimental values in the 1.4-6.5 MeV energy range.The(n,2n)double-differential cross-section has the greatest impact on the leakage spectrum results in this energy range,and the evaluation of the(n,2n)double-differential cross-section in ENDF/B-Ⅶ.1,ROSFOND-2010,and CENDL-3.2 has problems.The neutron leakage spectra of structural materials Fe,Al,Cu,Mo,and W simulated by the experiment match well,but the Co high energy range cross-section data are generally underestimated,and the Si calculation value is higher than 2 MeV.The Janus Phase 1 benchmark verifies that the MATXS-LFR multigroup cross-section library has good accuracy in calculating fast spectrum problems.The calculation and analysis of the lead-bismuth fast reactor showed that the weight function in the MATXS-LFR multigroup cross-section library has an impact on the calculation results of fine group cross-sections,and different weight spectra produce different fission neutron spectra,which will result in significant differences in the fast neutron flux in the main vessel.The study has a certain significance for reducing the uncertainty of multigroup cross-section libraries in lead-bismuth fast reactor shielding calculations.