Impedance Analysis of ECT Bobbin Probe for Steam Generator Tube Inspection

Eddy Current Testing (ECT) for steam generator (SG) tube inspection in nuclear power plants (NPP) is the most important non-destructive test during the plant outage. Bobbin probe is the most commonly used for the SG tubing inspection. The impedance, important parameter related to the signal of ECT, depends on the characteristics of bobbin probe to be used for the inspection. In this study, a system for acquiring the impedance data was made up and impedance analysis program was designed for effective data acquisition. Employing the system and program, the resonance frequencies were obtained and the impedance data were acquired for the bobbin probes for SG tube inspection. Experimental results are compared with the theoretical results and normalized impedance diagrams for the probes are offered in this paper. These experimental results gives not only a better understanding of impedance properties of the bobbin probes for SG tube inspection but also the information about the design and fabrication of the bobbin probe