Failure Assessment of Nuclear Piping Components Due to Combined Degradation Mechanisms by an Advanced Probabilistic Fracture Mechanics Code

Abstract

Probabilistic failure analysis of nuclear piping components due to a combined degradation mechanisms is a challenging issue. At present the majority of analyses were done by assuming a single failure mechanism for a specific location of a piping system. But in reality, this might not be an accurate approach. A tiny crack might be present in a weld location due to fabrication defect or initiated due to fatigue after a short incubation time of plant’s start up. This pre-existing or initiated crack then may be further matured by the synergistic effect of different probable degradation mechanisms e.g. fatigue, stress corrosion cracking, etc. In this study the development process of an advanced probabilistic fracture mechanics code has been described which can handle this combined failure mechanisms. Numerical examples are also presented to rationalize the use of such methodology.