Effect of through-wall stress gradients on piping failure probabilities

An approach has been developed that predicts leak and rupture probabilities of reactor piping in a structured parametric format. This approach applies the probabilistic fracture mechanics code pc-PRAISE (Piping Reliability Analysis Including Seismic Events) to address the mechanical and thermal fatigue life of piping. The probabilistic fracture mechanics model is applied to predict the relative effects of uniform stresses and through-thickness stress gradients on the reliability of stainless steel piping welds. Results generated using the numerical technique revealed that the calculated leak probabilities can be sensitive to the different types of stress gradients and to local stress concentrations.