Steam Tube Defect Characterization Using Eddy Current Z -Parameters

Steam generator tubing inspections use the impedance of a differential eddy current probe inside a tube as an indication of incipient failure. An axisymmetric finite-element computer code has been developed and utilized to calculate the impedances of the differential probe. The calculated values have been validated by comparison with experimental results. A Z -parameter model for a probe inside a steam tube utilizing differential coils is described, and the response of Z -parameters for the differential probe under various changes in the steam tube configuration is investigated.