Probabilistic burst pressure estimation for steam generator tubes with fretting wear

Considering steam generator (SG) tubes form the boundaries between the primary and secondary sides of nuclear power plants, maintaining their structural integrity, even in the presence of defects in tubes, is crucial. In this study, six burst pressure models were compared using available burst pressure test data for SG tubes with wear defects. The model that accounted for both the maximum and minimum depths of wear defects exhibited the best performance in predicting the burst pressure of flat and tapered wear defects. With the most suitable burst pressure model selected, probabilistic methods were applied to evaluate the structural integrity of SG tubes with wear defects. The proposed defect repair criteria, which consider inspection intervals of 1.5 or 3.0 effective full power years and a 5% burst probability, resulted in a less conservative evaluation compared to the existing repair criteria (40% through-wall).