Research On Seismic Mitigation Technology Of Nuclear Polar Crane

Ring crane of nuclear power station(referred to as nuclear polar crane)is a special bridge crane located on the circular track inside the nuclear island reactor plant.It is mainly used to lift the core electrical equipment of the reactor and serve the entire cycle of construction,operation and decommissioning of the nuclear power station.The safety of the nuclear polar crane is related to the safety and production efficiency of the entire nuclear power station.And the frequent occurrence of earthquakes is one of the important factors that limit the safety of the nuclear polar crane.Therefore,the seismic performance of the nuclear polar crane needs to meet the requirements of the seismic design specifications of the nuclear polar crane.However,with the continuous breakthroughs and innovations in nuclear power technology,it brings serious challenges to traditional nuclear polar crane design,using seismic mitigation device to reduce the seismic load on the nuclear polar crane structure is one of the practical ways to deal with this problem.At present,there are relatively few studies on the use of seismic mitigation device to improve the seismic performance of nuclear polar cranes,especially there are few vertical seismic mitigation device.Therefore,according to the design characteristics of the nuclear polar crane structure,without affecting the normal operation of the nuclear polar crane,the design of seismic mitigation device to improve seismic performance of nuclear polar crane has important reference significance for design of the nuclear polar crane.In this article,taking a 200 t third-generation nuclear polar crane as the research object,mainly using the method of finite element simulation analysis for research.Firstly,the finite element model of the nuclear polar crane is established and seismic resistance analysis is carried out to obtain the structural response of the nuclear polar crane under the action of earthquake.Then,according to the results of seismic calculation,combined with the structural characteristics of the nuclear polar crane,design two types of seismic mitigation device for vertical seismic waves.Finally,the seismic mitigation device is added to the original design model of the nuclear polar crane for seismic calculation.By comparing the calculation results before and after,the damping effect of the seismic mitigation device is analyzed,and the value range of the stiffness in the design process of the seismic mitigation device is calculated.The main content of this article includes:(1)Simplify the original design model of the nuclear polar crane,complete the establishment of the finite element model and the setting of the boundary conditions;(2)According to the requirements of seismic standards,select the most unfavorable combination of working condition to complete the static analysis,modal analysis and spectral analysis of the nuclear polar crane model;(3)Select nuclear polar crane structure to respond to dangerous points,and compare the calculation results of different working conditions to find the most unfavorable working condition to the seismic performance of the nuclear polar crane;(4)Design seismic mitigation device to ensure that the effect of seismic waves on the nuclear polar crane is alleviated without affecting the normal performance of the nuclear polar crane(5)Establish finite element model of nuclear polar crane with seismic mitigation device and conduct seismic analysis,compare with the seismic calculation results of the prototype,and analyze the damping effect;(6)The impact of the two seismic mitigation devices on the overall seismic performance of the nuclear polar crane are comprehensived analysis,and summarize the range of values stiffness suitable for each type of seismic mitigation devices design.The research content of this article provides reference for the design of nuclear polar crane structure based on seismic mitigation technology.