Physical-Thermal Coupling Of Reactor Core Based On Single Channel Model

After the Fukushima accident in Japan,China pays more attention to the safety of nuclear power.In reactor safety,temperature is an important parameter,which has a very important effect on reactor core safety.In order to enhance the safety of the core and obtain the temperature distribution in the core quickly and accurately,it is necessary to continuously improve the physical thermal modeling method.In this paper,based on the MCNP program,combined with the repetitive structure of the program itself and the appropriate modeling techniques to complete the modeling of reactor core,which will be calculated core power into written thermal program based on MATLAB,and then will get after the temperature conversion into a new density,modify the input file again,repeat the previous steps,completed the core physical thermal coupling calculation.In order to verify the reliability of the coupling calculation,the power distribution and other parameters were calculated,and the safety of the core is analyzed.Combined with the heat pipe factor,it is proved that the coupling calculation is better for the calculation of the radial power flattening of the core.For the temperature distribution,a single-channel steady-state model is selected for thermal analysis,and a new numerical calculation method-the half-boundary method is used to calculate the steady-state thermal parameters after coupling.Firstly,the basic equations of the half-boundary method in the one-dimensional cylindrical coordinate system are derived,and the temperature distribution under the first kind of boundary conditions is calculated by the half-boundary method,and the accuracy of the half-boundary method is verified by comparing the analytical solutions.The semi-boundary method was used to calculate the temperature distribution of the AP1000 fuel rod under the single-channel steady state model,and the influence of the material thermal conductivity on the radial temperature distribution was compared.Finally,the temperature distribution diagrams of axial pellets,cladding and coolant after physical-thermal coupling are obtained,which accord with the axial temperature distribution law of PWR gate element,and coincide well with the analytical solution,verifying the feasibility of using the half-boundary method to simulate the nuclear thermal problem.In conclusion,the core power and temperature distributions can be more close to the real state by using this physical-thermal coupling calculation method.