Development And Research On The Fuel Management Code System For Nuclear Core With High Power Density And Complex Geometry

With the research and development of nuclear cores with high power density and complex geometry,The core calculation codes based on diffusion theory are unsuitable for actual engineering design of these nuclear cores.Employing the “two-steps” method,a core calculation code based on discrete ordinate method with triangular mesh is developed in this thesis,aiming to meet the higher requirements of calculation accuracy and efficiency in actual engineering design.Firstly,the overall calculation process and framework of the calculation code system are determined in this thesis.Series of mathematic models employed in HELIOS code,including treatments of geometry and resonance models and transport and depletion calculation models,are analyzed.The application of least squares fitting method in the LINK code is also determined.Besides,a flexible control rods control model and a macro depletion calculation model in the core are developed.Secondly,in order to verify the calculation accuracy of assembly calculation code,some pin cell depletion experimental calculation models rooted in SFCOMPO-2.0 database and a simplified assembly calculation model are established,respectively.The calculation results indicate that the values resulted from assembly calculation code,HELIOS,are in good agreement with the reference values.Based on the least square fitting method,the LINK code is developed.With the employment of LINK code,the simulation values of the single assembly restructure problem in the code are in good agreement with the values calculated by the assembly calculation code,in which the maximum error of eigenvalues is 260 pcm.Additionally,based on the discrete ordinates method and the triangular mesh calculation kernel,a core calculation code CENTUM is developed in this thesis.A simplified core calculation model is established for the verification propose of the core calculation code CENTUM.The results indicate that the steady-state calculation values of the CENTUM code and the Monte Carlo code are in good agreement.The average error of assembly power in the core is 2.36%.The maximum error of core eigenvalue is 401 pcm,under different control rod positions.The core calculation code system developed in this thesis hold the practical engineering application capability for the engineering design and safety assessment of the core with high power density and complex geometry.