Fatigue Crack Propagation Analysis of Nozzle Corner Using the Influence Function Method

A calculation system has been developed in order to evaluate the thermal fatigue crack propagation of a semi-elliptical crack on the corner of a nozzle. One fatigue crack was assumed on the inner surface of the nozzle corner of a representative PWR reactor vessel. The stress intensity factors K were calculated at the deepest and outermost surface points of the crack using the influence function method. A database was prepared for the cracks with a depth of 0.022 t − 0.5 t (t: pressure vessel thickness) and an aspect ratio of 0.1a/c – 1.0 a/c (a: crack depth and c: half surface width). Eight-noded solid elements and the finite element analysis code MARC were used. The calculation system enables the propagation of fatigue cracks at nozzle corners to be carried out in a very short time.