Application Study Of A Boundary Method On Solving Heat Conduction And Neutron Transfer Problems

Temperature distribution and neutron transfer,as two of the most critical factors affecting nuclear power plants' operation safety and eost,must be accurately measured.Due to the complexity and safety issue encountered by the experimental measurements,numerical methods have become powerful tools in accurately and efficiently carrying out the temperature and neutron transfer calculations inside the nuclear reactor.In this thesis,a half boundary method(HBM)was proposed and applied to simulate the temperature field and neutron transfer behavior in fuel rods.Compared with the traditional methods such as the finite difference method,the finite volume method and the finite element method,this method has comparable accuracy but much higher efficiency.Moreover,because of HBM5s fast computational performance,it is particularly applicable to predict the real-time temperature distribution and neutron transfer behavior in components with a complex geometry,which requires a substantial computational cost when using traditional numerical methods.To perform the calculation via using HBM,the calculation domain was discretized first.A relationship between the adjacent two nodes was then established according to the physical equations.By recursive calculation,the relationship between the arbitrary node and the node on the boundary was hence obtained.Finally,the boundary condition and physical parameters were introduced to perform the simulation on the entire model.In order to verify the accuracy and efficiency of HBM,it was first applied to heat conduction and neutron transfer problems with different boundary conditions and various grid numbers.The simulation results were compared to theoretical results and those obtained by traditional numerical methods,which verified the accuracy of HBM.HBM also turned out to have a much higher calculation efficiency than traditional methods,particularly for the models with substantial grid numbers.HBM was then applied to calculate the stable and transient temperature distribution in the double vessels and fuel rods of a sodium-cooled fast reactor.The influences of rod shapes and bumup conditions on the temperature distribution in fuel rods were studied.Eventually,the temperature change and melting process of fuel rods in respond to LOCA and RIA were also carried out.Overall,the HBM proposed in this dissertation proved to be an effective and efficient numerical method in carrying out the heat transfer and neutron transfer problems in nuclear reactors.