Seismic Performance Analysis Of Diesel Generator Set For A Nuclear Power Plant

Energy is very important for human survival, and as well a necessary guarantee for economic development. Since 1991, Chinese own construction of the first civilian nuclear power combined to the grid, large civilian nuclear power plants has been constantly built and used in China. The safety of nuclear power also has been the focus of researchers. Japan nuclear leak occurred in 2011 proved that the appraisal of seismic performance for nuclear power equipment has been urgent. The diesel generator set belongs to nuclear power plant safety equipment which the 15 key equipment to ensure the safety of nuclear power station. As the last line of the security assurance, analyzing the seismic performance and evaluating the integrity of the structure has a very important practical significance.Therefore, on the basis of a large domestic state-owned nuclear power safety project, using the numerical simulation method for a type diesel generator set of seismic performance. The main contents are as following.(1) According to the seismic parameter evaluation report of the powerhouse, the design acceleration and the response spectrum of the ground motion were determined. The time history of earthquake acceleration as the calculation input of floor response was synthesized by Fourier series transformation. Effects of different dynamic shear modulus of the soil and the depth of the different soil layers were considered and combined with the actual structure of the powerhouse to establish the model of interaction between powerhouse and soil. The seismic dynamic response of the model was analyzed by using ABAQUS finite element software and the acceleration response spectrum of the floor under the OBE and SSE level ground motion was calculated.(2) According to the diesel generator set where the position in the powerhouse and the damping ratio of structural requirements, elevation-1.45 m, damping ratio of 2% OBE and 4% SSE level floor acceleration response spectrum were selected. The set seismic analysis model was divided into main system and subsystem by mass distribution. Based on the theory of vibration mode decomposition response spectrum, main system seismic performance was analyzed. The results show that main system was flexible, and the spring connection stiffness of the intermediate coupling was weak, and the acceleration of the turbocharger was the maximum of the whole model. According to the B level and D level of ASME, the results show that after the stress concentration of the common base was neglected, the seismic performance of the main system was good. At the same time, the bolts of the components meet the design requirements and the stress limit value of the ASME shows that it had good reliability.(3) In view of the subsystem of the diesel generator set, the crankshaft, camshaft, connecting rod assembly and various auxiliary pipelines were included. The subsystem seismic performance was analyzed by using equivalent static method, but the equivalent acceleration of earthquake was modified, the working conditions were neglected, the subsystem self- weight loads were superimposed. In the ASME standard, the B level standard stress limit of 10% was used as the evaluation criterion, the results show that the modified equivalent acceleration was reasonable, the subsystem can meet the stress limit value, the connecting rod bolt and all kinds of pipe connection bolt reliability was good and had a certain margin.