Study On The Input Ground Motion Of The Containment Vessel Of Nuclear Power Plants Based On Conditional Mean Spectrum

In 1951,Nuclear power generation was first used in the United States,it is more than 60 years since the nuclear power technology was put forward.Now there are more than 400 nuclear power plants in use all around the world.Compared with the traditional fuel such as coal,oil,gas,nuclear power is more environmental,more efficient,and cleaner.As one of the effective ways to solve the energy problems,nuclear power has attracted wide attention in the world.Now the construction of nuclear power plant in our country has developed rapidly,the site of nuclear power plant could be in the inland even in the earthquake region.We must pay more attention on the seismic performance of NPP.Thanks to the development of the finite element software,the dynamic time history analysis can be performed repeatly.According to code for seismic design of nuclear power plants,the horizontal ground motions and the vertical ground motions are required for the dynamic time history of nuclear power plant containment.Different ground motions may lead to different response of the structure,and the difference may be huge,so how to choose the appropriate ground motions is the concern.Probabilistic seismic hazard analysis is used to solve the problem,and conditional mean spectrum is used as the target spectrum of the input ground motion to obtain the input ground motions of nuclear power plant containment.Then we can get the procedure of calculating the target spectrum of the input ground motions of nuclear power plant containment.The main content is as follows:1.The concept and calculation of probabilistic seismic hazard analysis is introduced.The uniform hazard spectrum of NPP considered of all possible earthquakes in the future is calculated based on a fault model.The concept and calculation of seismic hazard disaggregation is introduced.And every single earthquake is analyzed to make sure of the dominant earthquake which causes the maximum damage to the site.Considered of single earthquake,the design response spectrum of curve form and UHS is calculated,and the difference of the two spectrum is discussed.2.The concept and calculation of conditional mean spectrum,and CMS in different sites and different conditional periods is calculated.The effect of parameters on the shape of CMS is discussed.Compared with DRS and UHS,CMS is used as the target spectrum of input ground motion.3.Based on CMS with different conditional periods,the most suitable ground motions for the target spectrum are picked and scaled.The finite element model of NPP is built with ABAQUS,and the dynamic time history analysis of NPP containment is performed with the input ground motions selected,so we can be sure that the conditional period of CMS can only be the first mode period of NPP containment which is 0.35 s.Compared with the PGA method and the epsilon method,the CMS method is more suitable to select input ground motions.And based on the model in this paper,the procedure of calculating the target spectrum of the input ground motions of nuclear power plant containment is stated.At the same time,the target spectrum of the input ground motions of nuclear power plant containment in different sites and under different design earthquakes is provided.