Evaluation of the J-Integral of a Crack in a Pressure Vessel Under Thermal Transient Loadings

Abstract

To assure the safe design of reactor vessels, the parameters of the fracture mechanics are evaluated for an assumed crack subjected to internal pressure and thermal loading. Several kinds of cracks are assumed to exist in the pressure vessel and two and three-dimensional finite element analyses are carried out. As the parameters of fracture, the J -integral and extended ones for a thermal field and a multi-phase material are used. The effect of the cladding on the J values is evaluated and discussed. It is shown that the contraction of the vessel wall, due to the decrease of the temperature at the inner surface, strongly affects the J value. Though three-dimensional analyses, the shape of the growing surface crack is estimated from the distribution of the J values along the crack front.