An ECT probe with widely spaced coils for local wall thinning in nuclear power plants

Toshihiro Yamamoto, Tetsuya Uchimoto, Toshiyuki Takagi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Currently, local wall thinning on the inner surface of a pipe is evaluated mostly by ultrasonic thickness measurement from the outer surface of the pipe in nuclear power plants in Japan. However, it has been pointed out that there are two major issues of this evaluation method. Firstly, this method is not able to evaluate local wall thinning from the top of a reinforcing plate that covers the outer surface of a pipe because this two-layer structure hinders the propagation of ultrasound. Secondly, because ultrasonic thickness measurement of a pipe wall is conducted at certain intervals on the outer surface of the pipe, it may overlook a hole-like defect if the defect size is small compared to this interval. We propose an eddy current testing (ECT) method using widely spaced excitation and pick-up coils to alleviate these problems. Our experimental results show this method can be applied to inspection of a double plate that consists of two 8 mm-thick austenitic stainless steel plates, and a defect indication is observed in a much larger area than the defect.

Original languageEnglish
Title of host publicationElectromagnetic Nondestructive Evaluation (XIV)
EditorsTomasz Chady, Stanislaw Gratkowski, Toshiyuki Takagi, Satish S. Udpa
Number of pages8
Publication statusPublished - 2011

Publication series

NameStudies in Applied Electromagnetics and Mechanics
ISSN (Print)1383-7281
ISSN (Electronic)1879-8322


  • Eddy current testing
  • Local wall thinning
  • Pancake coil


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