Development of probability of detection functions for evaluating integrity of axial outside diameter stress corrosion cracks in steam generator

Abstract

The reliability of an eddy current testing (ECT) inspection system depends upon the inspection technique and quality of analyst. In evaluating the integrity of a steam generator (SG) tube, degradation detection and sizing accuracy are considered performance measures of the nondestructive evaluation (NDE) system. A probability of detection (POD) model serves as a functional measure of the ability of an NDE system to detect degradation. It is one of the inputs in the operational assessment, and it is used to estimate the degradation during service via ECT of the SG tube. In this study, the POD functions of the inspection technique and analyst were obtained to quantitatively analyze the ECT bobbin probe for axial outside diameter stress corrosion cracks in SG tubes. This should serve to evaluate the integrity of the SG tubes. The depth and amplitude of defects were used as parameters of the POD model. Hit (detection) and miss (no detection) binary data obtained from destructive and nondestructive inspection of cracked tubes were also used.

Probability of detection model for the non-destructive inspection of steam generator tubes of PWRs

“…Finite element simulations were conducted to evaluate signals due to cracks; accounting for both the depth and length of a crack explicitly to evaluate POD quantitatively. Furthermore, combinational use of numerical simulations to evaluate the general dependency of signals on flaw parameters enables the construction of a reliable POD using fewer samples compared with a conventional POD analysis using only experimental data [13,14]. Whereas this study considered the eddy current inspection of steam generator tubes of PWR, the twodimensional POD model used in this study should be applicable to discuss POD of any nondestructive testing inspections, regardless of the target is either PWR or BWR, so long as signals obtained by the inspections are given as a quantitative one and numerical simulations can calculate signals due to a flaw with a known profile.…”

Evaluation of probability of detection (POD) studies with multiple explanatory variables

“…One of the major reasons for this is the discrepancy between aviation industries where POD has been proposed and developed and nuclear industries in the inspection reliability issues as pointed out in a recent literature [8]. Whereas several recent studies have reported success in applying POD that is essentially the same as those used in aerospace applications [9][10][11], a modified form of POD specifically for nuclear application is desirable.…”