Consideration of inspection uncertainties in the probabilistic assessment of steam generator tubing

Steam generators (SG) are periodically inspected to maintain high safety and integrity of the heat transport system in the nuclear plant. The integrity of SG tubing is affected by various degradation mechanisms, such as wear and stress corrosion cracking (SCC). SG tubing integrity assessment is periodically performed to ensure the tubing degradation does not exceed the structural limit in the upcoming operation cycles. This paper presents a probabilistic approach for integrity assessment of SG tubing with fretting wear degradation and highlights the importance of correct modeling inspection uncertainties, such as flaw sizing error, in the prediction. A case study is presented using actual data from a nuclear station, which illustrates the effectiveness of the proposed method.