Investigation of Frequency Mixing Techniques for Eddy Current Testing of Steam Generator Tubes in Nuclear Power Plants

Abstract

In eddy current testing (ECT) of steam generator tubes in nuclear power plants, it is very important to extract flaw signals from the signals compound by flaws and supporting structures. To perform such an important task, the multifrequency ECT methods are widely adopted since they have a well‐known capability of extracting the flaw signal from the compound signals. Therefore, various frequency mixing algorithms have been proposed up to now. In the present work, two different frequency mixing algorithms, a time‐domain optimization method and a discrete cosine transform (DCT) based optimization method, are investigated using experimental signals captured from a ASME standard tube. In this paper, we discuss the basic principles and the performances of these two frequency mixing techniques.