Seismic Analysis Research Of Nuclear Power Plant Polar Crane

Polar crane in nuclear station is one kind of special equipment.It is installed right above the core equipment including RPV(Reactor Pressure Vessel)and vapor generator etc.,and run on the circular track with dozens of meters high over the containment in the nuclear reactor plant.It is mainly used to hoist and transport the heavy and key equipment in the nuclear reactor plant such as RPV,vapor generator cover,voltage stabilizer and core barrel etc.,during the period of construction and cold-refueling.So it is the most important hoisting equipment in the in nuclear station for the above reasons.Polar crane lies in the classification of I class anti-seismic equipment related to the nuclear safety and the safety and reliability of the polar crane directly affects the security of the nuclear island.According to the related regulations,in order to avoid severe nuclear safety accident due to the falling of crane parts or equipment's being hoisting,the anti-seismic requirements of polar crane must be satisfied.Conclusively,seismic analysis is one of the important aspects in polar crane design and development.With technique upgrades of nuclear power and warning from Fukushima accident,successive upgrades and progresses of new generation nuclear station in terms of technique,structure and function are emerged,and more and more anti-seismic requirements are raised.As a result,it raises more new technical requirements and deeper research contents for the design and development of the large-scale polar crane as ancillary facilities for nuclear station.Meanwhile,due to the successive increases of design parameters in terms of elevating capacity,span and self-weight of polar crane and the successive increase of the seismic acceleration,both the load acted on the self-parts and that transferred to and acted on the plant structure increase successively,which will more and more affect the structural safety of the nuclear reactor plant.Conclusively,it is vital and impendency to conduct the deep seismic analysis research and optimal design on polar crane in nuclear station.The research object of this article is the large-tonnage polar crane from Taiyuan Heavy Industry Co.,Ltd.developed for the Chinese-designed 3rd generation large-scale advanced PWR(Pressurized Water Reactor)nuclear power station which is demonstration project.Aimed at initially used characteristics of the new generation technique including using flexible steel containment and using rim of polar crane to resist the seismic horizontal force,the research about the key techniques and analysis methods in terms of coupling dynamic response of polar crane and steel containment under seismic action and using various anti-seismic analysis method to assess the interaction between polar crane,support beam and steel containment was conducted to ensure the safety and reliability.The traditional response spectrum analysis and the response spectrum analysis considering residual stiffness response with missing mass mode were carried out via finite element analysis software ANSYS and the results were compared and contrasted.The impact and essentiality of improved seismic analysis to structure of polar care were specified.The seismic time-history analysis considering manufacturing tolerance was carried out due to the deficiency of response spectrum analysis.The wheel of polar crane and the track were verified according to the analysis results,and the structure of main girder was modified with the total mass decreased.As a result,the safety and reliability of polar crane under SSE seismic load were verified forwardly.Conclusively,loads of both self-departments and the one transferred to the structure of nuclear island containment plant were decreased forwardly.It can provide theoretical evidence and reference for the independent design and development of large scale polar crane used for nuclear station.