APPLICATION OF EDDY-CURRENT TESTING INSPECTION TO THE FIRST WALL OF FUSION-REACTOR WITH WAVELET ANALYSIS

The eddy current testing (ECT) technique is introduced for the non-des tructive evaluation of the first wall of a fusion reactor. With the ai m of in-service inspection of the frrst wall, a method to evaluate cra cks in the first wall is studied theoretically utilizing impedance sig nals and magnetic field data obtained from ECT. From the impedance sig nals, the depth of the cracks is determined using an impedance-depth c alibrating curve. Since an impedance signal may be caused by some unde sired factors as well as by a crack, an approach to extracting crack i nformation from such a composite signal is developed using wavelet ana lysis. For reconstruction of the surface shape of the cracks, the magn etic field data are inverted into the distribution of the current vect or potential T by solving an inverse problem and the wavelet coefficie nts of T are calculated to characterize the shape of the cracks. It is shown that the combination of ECT and wavelet analysis provides an ef ficient method of non-destructive evaluation of cracks in the first wa ll.