Research On The Failure Mechanism And Damage Of AP1000 Nuclear Island Structure Under The Impact Of Large Commercial Aircraft

With the progress of social economy and science and technology,the demand for nuclear power plant is increasing,which puts forward higher requirements for the safe operation of nuclear power plant.Especially after the 9 · 11 incident,the protection performance of nuclear power plant against the impact of large commercial aircraft has been a hot issue in the field of nuclear safety.The AP1000 nuclear island structure consists of an internal steel containment and an external reinforced concrete shield building.In this paper,the structure dynamic response,impact failure phenomena and general damage law of containment and shield building under aircraft impact are analyzed under five different initial impact velocities and five different impact heights respectively.The finite element model of the AP1000 nuclear island structure is further established,and six different initial impacts are analyzed under the action of velocity and five different impact heights,the impact damage phenomena of aircraft and nuclear island structure,the impact force time history,impulse time history,residual velocity time history and kinetic energy time history of aircraft are analyzed.The maximum value of aircraft impact force and the impulse,residual velocity and kinetic energy of aircraft at the end of impact are compared and analyzed.The following conclusions can be drawn from the above research:1.The accuracy and effectiveness of the built aircraft finite element model are verified by the finite element software ANSYS/LS-DYNA,and the accuracy of the AP1000 nuclear island structure shield building is verified by using numerical simulation results of aircraft impact rigid walls and the results of the Riera method theoretical calculation;2.The dynamic process and effect of aircraft impact can be effectively predicted by the method based on missile target contact coupling analysis.Compared with the theoretical calculation results of Riera method,the maximum error of aircraft impact force peak value and impulse is only 1.11% and 3.73%;3.The whole process of large commercial aircraft impacting only the containment and shield building of the AP1000 is calculated and analyzed.The impact damage phenomenon and penetration size of the containment and shielding building are analyzed.The dynamic response of the containment and shield building structure under the influence of different initial impact velocity and impact height is discussed.The results show that the aircraft impact effect at the equivalent steel beam of containment is greater than that at other parts,but it has good resistance to aircraft impact.The most dangerous location of the containment is at the junction between the containment and the dome,and the dome is the weakest(not penetrating)under the axial horizontal impact of the vertical nuclear island structure.The damage of the cylinder section of the shield building is similar,and the damage is more serious than that at the impact of the safety water tank.With the increase of the initial impact velocity,the damage of containment and shield building is more concentrated,but the distribution range of their cloud images is expanded;4.The dynamic response of the aircraft to only impact containment and shield building is studied and analyzed.The results show that the peak value of the impact force and the impulse at the last moment vary linearly with the initial impact velocity,and the residual velocity and kinetic energy of the aircraft at the final moment are nonlinear.The peak value of aircraft impact force is mainly contributed by engine impact,and the maximum is about 7 times of the front fuselage;5.The whole process of large commercial aircraft impacting on the AP1000 nuclear island structure is calculated and analyzed.The dynamic response of the aircraft impact force time history is analyzed.The dynamic response of containment,shield building and nuclear island structure is compared and analyzed.The results show that the shield building has a good resistance to aircraft impact.The kinetic energy of the aircraft at the end of the impact is less than the first two.The initial impact velocity of the containment penetration in the nuclear island structure is 1.75 times that of the impact containment only,and the penetration size is smaller.