Wavelet analysis of poorly-focused ultrasonic signal of pressure tube inspection in nuclear industry

Huan Zhao, Anthony Gachagan, Gordon Dobie, Timothy Lardner

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

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Pressure tube fabrication and installment challenges combined with natural sagging over time can produce issues with probe alignment for pressure tube inspection of the primary circuit of CANDU reactors. The ability to extract accurate defect depth information from poorly-focused ultrasonic signals would reduce additional inspection procedures, which leads to a significant time and cost saving. Currently, the defect depth measurement protocol is to simply calculate the time difference between the peaks of the echo signals from the tube surface and the defect from a single element probe focused at the back-wall depth. When alignment issues are present, incorrect focusing results in interference within the returning echo signal. This paper proposes a novel wavelet analysis method that employs the Haar wavelet to decompose the original poorly focused A-scan signal and reconstruct detailed information based on a selected high frequency component range within the bandwidth of the transducer. Compared to the original signal, the wavelet analysis method provides additional characteristic defect information and an improved estimate of defect depth with errors less than 5%.
Original languageEnglish
Title of host publication44th Annual Rview of Progress in Quantitative Nondestructive Evaluation
EditorsDale E. Chimenti, Leonard J. Bond
Place of PublicationMelville, New York
Number of pages9
Publication statusPublished - 20 Apr 2018
Event44th Annual Review of Progress in Quantitative Nondestructive Evaluation - Provo, UT, USA, Provo, United States
Duration: 16 Jul 201721 Jul 2017


Conference44th Annual Review of Progress in Quantitative Nondestructive Evaluation
Country/TerritoryUnited States
Internet address


  • pressure tube fabrication
  • wavelet analysis
  • focused ultrasonic signals

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