TITLE

A novel crack reconstruction method for steam generator tube ECT with noise sources outside

AUTHOR(S)
Huang, Haoyu; Takagi, Toshiyuki; Fukutomi, Hiroyuki
PUB. DATE
May 2000
SOURCE
AIP Conference Proceedings;2000, Vol. 509 Issue 1, p513
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In eddy current testing of steam generator tubes, the signals obtained are always noised by many factors because of the complex environment. Some of these noise factors are caused by the support plates, the expansion part of the tube and the tube sheets outside. Previous works show that the noises of support plates can be reduced by a multi-frequency method. However, the elimination of noises from the expansion part of the tube is proved impossible using the multi-frequency method only. A new signal processing method is introduced in this paper by applying a differential filter using the two dimensions scan data. Signal noise ratio (SNR) is increased significantly, even a small signal from outer defects can be recognized. Furthermore, a new method for the crack reconstruction from these noised signals has been developed with a fast signal prediction and the conjugate gradient algorithm considering the outside ferromagnetic structures such as support plates and tube sheets. The electromotive force signals used here for the crack reconstruction are laboratory data obtained by a newly developed four-sensor probe with mutual induction and differential outputs. Shapes of artificial cracks are reconstructed satisfactorily in short CPU time. © 2000 American Institute of Physics.
ACCESSION #
6029088

 

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