Seismic Behavior And Failure Mechanism Of Auxiliary Equipments In Nuclear Power Generating Stations

Auxiliary equipments in nuclear power generating stations should have fine seismic behavior that is an important condition for safe operation of nuclear power generating stations unde assumed seismic ground motion. Before now the research on seismic safety of nuclear power generating stations focused into principal structures and was behind in equipments. Equipment relevant provisions in seismic design code for nuclear power generating stations in China is also not sufficient In pace with successive construction of nuclear power generating stations in China,it is necessary to develop a \igorous research on seismic safety of auxiliary equipments in nuclear power generating stations. Because of structural complexity of equipments,it is difficult to understand its seismic behavior only with individual anal)tical calculation or structural test. Based on combination of theoretical analysis and structural test this paper studies seismic behavior and failure mechanism of some typical equipments in nuclear power generating stations such as air processor,centrifugal ventilator and condenser in nuclear class. The study involves calculating model,seismic input,response calculation,strength check,measured point installation,input history inversion,exitation torelance,response measuring and synthetic assessment of seismic ability of equipments. The process of theoretical analysis and test study can be summarized as follows:(l)In the basis of linear elastic assumption for structure a finite element model was founded. With inputting floor response spectra for different floor,the positions of maximum response spectra for different floors,the positions of maximum response was obtained by primary calculation and they gave a reference to arrangement of sensors and strain gauges in test. (2)Prototype struclural test was carried out on the large scale shaking table. Natural vibration behavior and damping ratio of the structure were obtained with frequency scanning and parameter identification.Mechanic magnitudes were measured with sensors and strain gauges for simulated horizontal floor response spectra at given floor as seismic input (3)Response of the structure was recalculated with measured response spectum of shaking table input as an actual seismic excitation.(4)Because of validity of the calculating model bycomparison between analytical calculation and test result,3D seismic response analysis was conducted with analytical calculation method. (5)Based on the response property of structures of different type and its cause analysis,the failure mechanism of the structures under seismic ground motion were researched and their behaviors were assessed. (6)Using the calculating model verified by test result,isolation effectiveness of structures with different parametric spring bases were compared each other. There are no many experiences used for refersnce of this research project. The findings of this research project give a reference to supplement and revision of equipment part of seismic design code for unclear power generating stations in China...