R&D On A Non-linear Dynamic Analysis Code Considering FSI For The Key Equipments In A Nuclear Power Plant

Nuclear power plants’internal structure in operationis vibrating inevitably. Even in the extreme case, like the earthquake disaster, collision and deformation between the structure occur. At the same time, the fluid is of a great impact to influencethe structure’s motion, lead the vibration expresses strong nonlinear motion. So studying fluid solid coupling effect under the accident conditions (such as earthquake accident), developing special nonlinear dynamics calculation softwareof nuclear power plant is necessary.This paper analyses the rod drop’s physical mechanism, considersthe effects offluid solid coupling effect, of the fluid resistance to components in the rod drop process, andof the contact between the control rod assembly and the control rod guide tubeto the rod drop time. In the spent fuel pool frame vibration analysis, we research frame motion’s effects on the fluid flowing within the gap of the frame and the wall of the pool and the frame and the frame under earthquake condition.We also research the dynamic characteristic parameters,like fluid added mass and added damping, and develop the fluid solid coupling model between spent fuel pool and frame.This paper analyses the transverse vibration equation of elastic structures in the fluid excitation, uses of Newmark-β method for numerical analysis, analysis fluid resistance to the elastic structure in fluid and calculation method, and analysis the influence of drag tofluid resistance to the elastic structure. the improved Hertzdamp model is applied to the problem of collision between the control rod component and a control rod guide tube, the spent fuel pool storage rack and rack, rack and tank wall. Based on the theoretical analysis, we establish and deduce the calculation method of nonlinear dynamics of nuclear power plant structure, develop the nonlinear dynamics response analysis software for the nuclear power plant, which can be used tostudyrod drop time and the spent fuel rack’sseismic calculation.Through the calculation of these two examples, and compared with experimental data, it provesthattheory analysis, calculation methods and programwe proposed in this paper are applicable and reliable, the program can be used to calculate the nonlinear dynamic problems in the nuclear power plant such as the control rod drop time calculation andseismic response analysis ofstorage rack.