Probabilistic structural integrity assessment for Inconel690 alloy steam generator tube with volume defect

Highlights: • Non-destructive examination and 350℃ bursting pressure tests of defected tube. • Probabilistic bursting pressure model of Inconel690 tube with volume defect. • Fit for service criterion for Inconel690 tube with less conservatism. Fit for service(FFS) assessment of Steam Generator Tube(SGT) plays a key role in safety operating of Pressurized Water Reactors. Engineering practices have emerged probabilistic method is a powerful tool in reducing redundant safety margin of FFS assessment strategy. The aim of this work is to develop a probabilistic structural integrity assessment method for typical Inconel690 alloy SGT with volume defect. The study consists of four parts: Firstly, an experiment program including tensile test, eddy current examination and SGT bursting test were introduced. Then, potential bursting pressure models were analyzed based on test dataset. Proper bursting pressure model was suggested. Thirdly, probabilistic bursting pressure prediction model was developed based on Monte Carlo Simulation. At last, parametric study was performed and an application instance on anti-vibration bar fretting wear was presented. The results indicated the proposed SGT structural integrity assessment method is less conservative than current repair criterions. This study represents a further step towards developing of smart FFS assessment of Nuclear Power Plant.