Research On Seismic Isolation Of A Nuclear Island Plant

With the increasingly serious environmental pollution and the huge demand for clean energy in society,nuclear power is gradually becoming an important part of energy supply.But the huge damage caused by the accident at the Fukushima Nuclear Power Plant(NPP)made us realize the NPP must be able to withstand earthquakes of a certain intensity.Due to process limitaions,the horizontal and vertical arrangement of the nuclear island plant is irregular,therefore,the influence of the arrangement of bearings on the response of the upper structure is very complicated.At the same time,due to the cutting-edge importance of NPP projects,countries have rarely published their research and application results of their seismic isolation technology of NPPs.In addition,in order to solve the amplification effect of vertical seismic action on the structural response after isolation,scholars at home and abroad have proposed some concepts or developed related products of three-dimensional base isolation systems,but the isolation effects in the specific application of the NPPs is less studied,either the vertical stiffness and vertical damping of those three-dimensional base isolation system.The seismic isolation of a NPP under the action of three-dimensional earthquake is studied in this paper,the main work is as follows:(1)Generated design acceleration time history according to relevant domestic and foreign specifications.Studied the seismic isolation of NPP with general finite element software ANSYS,compared a large number of trial results and optimized the arrangement of bearings,then obtained an arrangement scheme of base isolation with better isolation effect.And two ideas of simulating spatially arranged moving viscous damper in ANSYS is discussed;(2)Analyzed the influence of the vertical stiffness of some bearing on the isolation effect of local structures,used elastic sliding bearings suppresses the amplification effect of the vertical response of the local structure.Secondary shock absorption for large-span slabs,cantilever panels between the inner and outer structural joints and bottom slabs were studied,then obtained proper arrangement and parameters of viscous damp;(3)Investigated the impact of yield ratio and concrete material damping on isolation effect and obtained appropriate yield ratio range which is suitable for isolation of NPP,and showed the good effect of increasing the damping of concrete material on energy dissipation;Calculated the bending and torsional stiffness of rubber bearings and inspected the vertical corner of the rubber bearings;(4)Based on the concept of three-dimensional base isolation,the influence of vertical stiffness and vertical damping of isolation layer on the isolation effect is studied and provided reference for the development of three-dimensional isolation system.