Seismic Response Analysis Of The Gravity Tank And Nuclear Island In Layered Rock-soil Site

Based on Sanmen's nuclear power plant in Zhejiang and Haiyang's nuclear power plant in Shandong,China actively promote the localization of the third-generation AP1000 nuclear power plant,and CAP1400 nuclear power plant with installed capacity of 1.4 million KW represents China's independent intellectual property right of large passive advanced PWR nuclear power project is also in the research phase.The passive containment cooling system gravity tank(PCS tank)at the top of AP1000 and CAP1400 nuclear shield building adopts the new concept of structural design.During emergency disposal,the water in the PCS tank automatically flows down along the steel containment shell by gravity,and then take away the heat of the nuclear reactor by water evaporation,it has a more reliable function and security.The Housner model recommended by the Code for seismic design of nuclear power plants is not applicable to fluid-structure coupling analysis for complex shape nuclear liquid storage structure,so it's necessary to modify the Housner model,and apply it to the seismic response analysis of liquid storage structure of the nuclear island.In the absence of high-quality coastal nuclear power plant site,China has completed the siting of inland nuclear power plants during the 13 th five-year plan.However,taking into account China's frequent earthquake and the potential radiological hazard of nuclear power plants,it's necessary to evaluate the safety of the seismic response of the proposed nuclear power plant in non bedrock and layered soil site,to ensure the nuclear power plant has the ability to withstand frequently occurred earthquakes with large intensity and other external events,and ensure the functional integrity and structural safety of the nuclear island and gravity tank.In conclusion,the Housner model which is recommended by the Code for seismic design of nuclear power plants was modified,and a better modified method of 3-D equivalent mass-spring model was proposed.The modified method and 3-D equivalent model were applied to the PCS tank of the nuclear island,and Soil-Structure interaction was considered,finally the seismic response of the model of nuclear island on the layered rock-soil was studied.The main contents of this paper are as follows:(1)According to the assumption of hydrodynamic pressure theory and rigid wall theory,the analytical solution of velocity potential analysis theory and the simplified method of Housner model was briefly introduced.It's necessary to solve the Navier-Stokes equations with free surface fluctuation and the initial boundary value problem of Laplace equation when analyzing the fluid-structure coupling problem of liquid storage structure.The simplified method of Housner model avoids the solution of nonlinear equations,the solution form is simple and clear,and has high computational accuracy,but it's not suitable for fluid-solid coupling analysis of complex shape nuclear power storage structure.(2)Based on the Housner equivalent model,the parameters of the reservoir volume inside the tank were introduced firstly,then considering the annular tank and it's equivalent mass-spring model is a virtual parallel system consisting of two cylindrical tanks and their corresponding equivalent mass-spring model.Finally,the parallel equivalent model correction method and the parameters calculation formula were deduced,the results were compared with the numerical results of the finite element model,and 3-D equivalent mass-spring model for the hydrodynamic analysis of the fluid inside PCS tank was proposed.(3)Based on the above theoretical study of equivalent model and parameter calculation formula,through theoretical proof and example comparison calculation,the correction parameters of the reservoir volume inside abnormal tank were introduced firstly.The empirical method and the parameters calculation formula of the equivalent model are fitted directly,and compared with the numerical results of the finite element model,the correctness and applicability of the modified method and model parameters are verified.(4)Aiming at CAP1400 nuclear island structure on the layered rock-soil site,considering the soil-structure interaction,using visco-elastic artificial boundary and explicit analysis method of the finite element software ABAQUS,the seismic response of the nuclear island and the surface of the layered rock-soil site under the action of AP1000 spectrum artificial ground motion?ANXIAN natural ground motion and Kumamoto natural ground motion were calculated respectively.