Research On Calculation Model And Dynamic Response Performance Of Nuclear Power Plant Against Large Commercial Aircraft Impact

Nuclear power is a kind of clean energy,which plays an important role in solving the power crisis,alleviating air pollution,adjusting energy structure and stimulating economic growth.Safety first has always been an important cornerstone of the sustainable development of nuclear power.After the "9·11" incident and Fukushima nuclear accident,the safety requirements of nuclear power engineering structures have been improved day by day,and the ultimate bearing capacity has been paid more and more attention.As a kind of super design basis event,large commercial aircraft impact has been included in the newly released GB/51390"Technical Standard for Concrete Structures of Nuclear Power Plants" in 2020.The reliability of evaluation methods and technical means of nuclear power structure against large commercial aircraft impact is closely related to the safety of advanced third and fourth generation nuclear power technology.There is a lack of systematic technical data for reference at home and abroad.Research in related fields has been highly valued by nuclear power authorities and large nuclear power engineering enterprises.According to the actual needs of the third and fourth generation nuclear power projects,this dissertation mainly focuses on the improvement of Riera model of aircraft impact load curve in the field of engineering design;the influence of seismic isolation measures in strong earthquake area on the dynamic response of nuclear power structure against aircraft impact;considering the factor of structure-soil-interaction(SSI),the analysis method and influence law of aircraft impact of nuclear power buildings under inland non rock foundation conditions are mainly discussed;the in-depth systematic research on the anti-aircraft impact dynamic performance of the specific building structure of the fourth generation nuclear power plant was carried out.These research results can enrich and improve the technical means and basis of aircraft impact resistance of nuclear power plant.The specific research contents and achievements are as follows:1.A modified Riera model is proposed to calculate the impact forces on the fuselage,wing and engine by considering the influence of aircraft type,containment radius and aircraft impact angle.As an important method to calculate aircraft impact load,Riera method can only deal with the problem of impacting the rigid plate at the beginning,and now it can deal with the problem of impacting the circular containment.However,it cannot consider the contribution of different parts of aircraft such as fuselage,wing and engine to the total impact force.The impact angle of aircraft also faces the same problem.Aiming at the problem of aircraft impacting cylindrical containment and inclined impacting plane rigid target,based on the refined finite element models of Airbus A340-300 and Boeing 767-200ER,the influence of containment radius and impact angle on the impact force and impulse of fuselage,wing and engine is analyzed.Based on the aircraft impact force,the concept of total impulse reduction rate of impact force is introduced to summarize the change rule of total impulse reduction rate of impact force with radius and impact angle in different parts of aircraft.And then,the Riera model is modified based on the summarized rules.2.Based on the refined CPR1000 containment and a third generation nuclear power plant model,the coupling dynamic response of the seismic isolation and aircraft impact is simulated and analyzed.The nuclear power plant adopting isolation technology is equivalent to placing weak isolation layer at the bottom of the base-mat.The analysis of the influence of the isolation bearing on the dynamic response of the superstructure can provide a reliable reference for the application of the isolation technology.There are two aspects in the coupling dynamic response analysis of the nuclear power building with seismic isolation.The one is using three different types of aircraft impact loads to study the influence of horizontal stiffness of seismic isolation on the dynamic response of CPR1000 containment.Then another is simulating the process of Airbus A340-300 aircraft impacting a third generation nuclear power plant with seismic isolation at different heights.The results show that the weak isolation layer beside the base-mat weakens the restraint effect of the fixed foundation on the superstructure,which will significantly change the dynamic response of nuclear power buildings under aircraft impact.The damage and failure state of nuclear power buildings under aircraft impact will not be affected by the arrangement of isolation bearings.The influence of isolation bearings should be analyzed from displacement response and acceleration response.In addition,in some extreme cases,if the aircraft impact load exceeds the bearing capacity of the isolated nuclear power building,the safety of the nuclear power building will be seriously threatened.Therefore,the influence of seismic load and aircraft impact load should be considered in the design of isolation bearing.3.Considering the influence of SSI effect,the influence factors of dynamic response of a third generation nuclear power plant under aircraft impact and the propagation and dissipation law of aircraft impact vibration in the foundation area are studied.In the future development of inland nuclear power,nuclear power plants will inevitably be built on the soil foundation with poor site conditions.Considering the impact of SSI in aircraft impact analysis is a necessary condition to obtain reliable analysis results.The strong vibration caused by aircraft impact can even affect the safe operation of adjacent buildings through the soil foundation.For the non-rock foundation,foundation excavation and foundation embedment are important factors,which greatly increase the contact between base-mat and foundation of nuclear power plant.In view of the above situation,combined with five kinds of standard sites of AP1000,the influence of site conditions on the dynamic response of a third generation nuclear power plant under the impact of Airbus A340-300 aircraft and the influencing factors of impact vibration propagation in the soil foundation are studied and analyzed.The influence of embedded depth,aircraft impact height and impact direction on the vibration response of nuclear power plant is analyzed.The results show that the vibration response of structures and equipment located on the base-mat will be significantly affected with the change of site conditions from hard to soft.It will weaken the high frequency component energy and acceleration peak value of the vibration response propagating outward along the foundation.Different impact positions,including different impact direction and impact height,will affect the path of impact vibration propagation,and the impact on vibration response cannot be ignored.The increase of embedded depth increases the restraint effect of the foundation on the superstructure,which will reduce the vibration response of the equipment and structure on the base-mat to a certain extent.4.Based on the refined model of a fourth generation nuclear power plant,the dissertation studies the ability of cylindrical,spherical and plane external walls to resist aircraft impact,and analyzes the influence of different reinforcement schemes on the damage and deformation of nuclear power plant.The dynamic response of the reactor building and spent fuel building under the impact of Airbus A340-300 aircraft is studied based on the refined model of a fourth generation nuclear power plant.It can be seen from the research results that the spherical dome external wall can significantly improve the structure's ability to resist aircraft impact.For the plane exterior wall,it is necessary to avoid the long span between the internal connected walls and the large height between the floors.In addition,the design of protective structure outside the important building,the reinforcement scheme with good impact resistance like tie bars and the increase of reinforcement ratio can significantly improve the anti-aircraft impact capacity of the structure.