| Reactor Pressure Vessel is considered irreplaceable,and runs under a harsh environment of high temperature,high pressure and neutron irradiation.So the service-induced defects are inevitable during the design life.So the study of regularity of three dimensional crack propagation of Reactor Pressure Vessel nozzle corner crack is necessary and significant,and can solve the problem of two dimensional model that can't represent the K variation regularities along the crack front.In this paper,the stress distribution of the reactor pressure vessel under design conditions is calculated,and the highest stress concentration area is found.The finite element model of the AP1000 reactor pressure vessel with inlet nozzle cracks is established,and the distribution of stress intensity factor along the crack front is calculated,and compared with the results obtained by the weight function method.Then three dimensional crack propagation of Reactor Pressure Vessel nozzle corner crack are performed: 1)the initial crack is in the longitudinal section of in-let nozzle;2)There is a 15° angle between crack face and the longitudinal section of in-let nozzle;3)There is a 30° angle between crack face and the longitudinal section o f in-let nozzle.The results indicate that the nozzle-cylinder intersection areas are high stress concentration area.The peak stress of the area exceeds the yield limit of the material,and it is easy to crack under the periodic load.The 1/4 wall thickness corner crack at the inlet nozzle corner will not affect the safe operation of the pressure vessel.Under the low load level condition,the K_I value obtained by the weight function method are more close to the average value of K_I obtained by finite element method.While under the high load level condition,the K_I value obtained by the weight function method is larger than that of the normal value.The slope initial crack is gradually inclined to the longitudinal section of the inlet nozzle,and the crack becomes I style. |
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