Failure of components with surface cracks of the containment steel 15MnNi63

In this paper, the burst pressure of the containment of a pressurized water reactor after a loss-of-coolant accident is calculated on the basis of fracture mechanics principles. The failure criteria applied include linear-elastic fracture mechanics, plastic instability and the two-criteria method. Experiments with plates containing semi-elliptical surface cracks have been performed to assess these methods for 15 MnNi63 containment steel. A leak-before-break evaluation showed that cracks with depths of less than a quarter of the thickness can be expected to exhibit unstable fracture of the spherical part of the containment. (author)