Prediction of Bobbin Probe Eddy Current Signals for Tubular Components with the Conductivity and Permeability Variation

Abstract

Steam generator (SG) tubes are pressure boundaries which separate the secondary unit from the primary one in nuclear power plants, so that they play a critical role in safe operation of nuclear power plants. Eddy current testing (ECT) is widely used in in-service inspection as well as pre-service inspection of the SG tubes. The interpretation of ECT signals, however, is truly a difficult task since ECT signals is changed not only by the flaws in SG tube but also by the variation in material properties such as conductivity and permeability. In the present work, the changes in ECT signals induced by the variation of the conductivity and the permeability of SG tube were simulated by using two dimensional electromagnetic finite element modeling. The results can be used for the discrimination of non-relevant ECT signals.

Detection of Magnetic Phase in the Steam Generator Tubes of NPP

“…Furthermore, PVC such as the build-up of magnetite (Fe 3 O 4 ) and MP on the secondary side of the SG tubing has no direct effect on the tube integrity but it causes spurious EC test results (Kim et al, 2004). The relative permeability of the PVC is greater than 1, and with a number of ferromagnetic metals, a value of several thousand can be reached.…”