| In a nuclear reactor,the phenomena are commonly dependent on both thermal-hydraulics and nuclear physics and their interaction.The simulation of the phenomena in a reactor has gradually changed from the calculation of nuclear physics and thermal-hydraulics processes to the simultaneous solution of two fields with the consideration of their coupling effect.In the conceptual design stage for a reactor,the design calculation was conducted in a separate manner.With the development of designing process,the coupling calculation method is required and often used to ensure that the thermal safety parameters are closer to the reality when entering the stage of safety design.The research of the simulation with consideration of coupling effect in a reactor originated on the basis of the coupling between the single channel model and the neutron transport model in the early stage.Nowadays,more refined sub-channel coupling program and CFD coupling program have emerged to resolve such cases.The key factor to ensure the availability and feasibility of the coupling program is to identify the sensitivity parameters of the coupling analyzer,to determine the reasonable convergence criteria of the coupling and to evaluate the uncertainty of the coupling program.Under the intense requirement on the development of the method around validation/verification,uncertainty quantification and sensitive analysis,in this thesis,the availability of coupling analysis tools based on subchannel analysis program and neutron transport program developed was studied in several aspects.Through sensitivity analysis and uncertainty analysis,the main influencing factors affecting the accuracy of coupling calculation results are identified,and the coupling calculation process is optimized according to the uncertainty analysis results.The main researching contents and the major conclusions of this thesis are stated as follows:1.In this thesis,a code for analyzing the coupling effect of nuclear physics and thermal-hydraulic was developed based on the subchannel analysis program COBRA-Ⅳ and the three-dimensional Monte Carlo neutron transport program MCNP5.By using PYTHON language,the control scripts of core-Ⅳ and MCNP5 are designed to control the coupling calculation of the subchannel analysis program and the 3D Monte Carlo neutron transport program,and the strategies and specific methods to realize the coupling calculation are proposed.In this thesis,an innovative convergence criterion for coupling calculation based on uncertainty result is proposed.2.taking a fuel assembly as the research object,the simulation work has been carried out based on the developed tool for the steady state of a reference reactor,The analysis of the models was performed and the key model parameters were also analyzed.The developed tool was validated against the data in public literatrue.3.Based on PYTHON language,A house code for sensitivity analysis and uncertainty quantification of the coupling analysis program was developed independently,and the correctness and availability of the developed method was verified by comparing the results from this code with the calculation results under the open code under CASL framework.By using this tool,the parameter sensitivity of the coupling calculation program is analyzed by the meta-effect method,the sensitivity degree of the parameters studied is determined,and the ranking results of the influence of different input parameters on the output parameters of the coupling calculation are given.4.Based on the developed calculation tool,the uncertainty in the calculation of coupling analysis in a fuel assembly module is evaluated through an example,and the uncertainty distribution characteristics of key parameters are given.The results show that the uncertainty analysis results have a good envelope for the coupling calculation results.At the same time,the influence of coupling... |
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