Sensitivity And Uncertainty Analysis For Nuclear Data Based On One-step Determistic Code

With the continuous development of calculation methods and codes,the uncertainty of nuclear data will become the main source of uncertainty in core physics calculation.The traditional two-step core analysis method can not meet the requirements of high fidelity and high security of the new-concept nuclear energy system.That is,the model introduced in the sensitivity and uncertainty(S&U)analysis of nuclear data has a complex process with many approximations.At present,the2-D/1-D coupling method has the characteristics of high fidelity and high precision,which make it the major method for the one-step calculation of the whole reactor core.It is necessary to study the uncertainty analysis function of the high-fidelity one-step deterministic code to meet the safety analysis requirements of the new nuclear energy system.Therefore,in this thesis,related nuclear data S&U analysis and multi-group nuclear data adjustment methods are studied based on the advanced 2-D/1-D transport code.Firstly,the adjoint transport theory in the 2-D/1-D coupling method is studied.The mathematical adjoint and physical adjoint theories are applied to the 2-D/1-D transport solver to achieve the applicability of the perturbation theory on the 2-D/1-D coupling method,obtaining three different adjoint flux distributions.The characteristics of the three adjoint flux distributions and their differences in the calculation of sensitivity coefficients are compared.Besides,the adjoint flux distributions are applied to dynamic parameters calculation and critical boron concentration search.Therefore,the correctness of the adjoint neutron flux solution is verified,which lays a foundation for the S&U analysis method research.Secondly,the eigenvalue S&U analysis method in the 2-D/1-D coupled model is studied based on the traditional perturbation theory.Compared with the traditional two-step code,the sensitivity of the eigenvalue to the nuclear data can be directly obtained.The uncertainty introduced by multi-group nuclear data is obtained by combining with the new covariance data applicable to the code energy group structure.Thirdly,the analysis method of generalized sensitivity and burn-up calculation uncertainty in the 2-D/1-D coupled model is studied by combining with the generalized perturbation theory(GPT)and the forward sensitivity analysis procedure based on the reduced-rank model(FSAP-ROM).An algorithm for solving generalized fixed source equations(GFSE)using the coarse mesh finite difference(CMFD)is proposed based on GPT,accelerating the process significantly.The FSAP-ROM is used,which solves many obstacles in the application of the GPT applied to the 2-D/1-D coupling method.Besides,FSAP-ROM is applied to the multi-response generalized sensitivity analysis and the burn-up calculation uncertainty analysis.Finally,the multi-group nuclear data adjustment method of the 2-D/1-D coupled model is studied.The generalized linear least squares method(GLLSM)and the random sampling method(RSM)are used to avoid the poor calculation accuracy of certain multi-group nuclear data.GLLSM is to solve nuclear data adjustment problems that take the eigenvalue as measured values.In contrast,RSM is to solve nuclear data adjustment problems that take multiple responses as measured values.Numerical verification shows that both methods improve the accuracy of multi-group databases.According to the above research,the high-fidelity one-step S&U analysis code KYADJ is developed in the thesis based on the 2-D/1-D transport code KYCORE.Numerical verification shows that KYADJ has a comprehensive S&U analysis system and high-precision S&U analysis results.On this basis,a multi-group nuclear data adjustment function is developed,which promotes the engineering application of the2-D/1-D transport code.