Bayesian analysis of flaw sizing data of the NESC III exercise

Non-destructive inspections are performed to give confidence of the non-existence of flaws exceeding a certain safe limit in the inspected structural component. The principal uncertainties related to these inspections are the probability of not detecting an existing flaw larger than a given size, the probability of a false call, and the uncertainty related to the sizing of a flaw. Inspection reliability models aim to account for these uncertainties. This paper presents the analysis of sizing uncertainty of flaws for the results of the NESC III Round Robin Trials on defect-containing dissimilar metal welds. Model parameters are first estimated to characterize the sizing capabilities of various teams. A Bayesian updating of the flaw depth distribution is then demonstrated by combining information from measurement results and sizing performance.