Development of a Guided Wave Technique for the Inspection of a Feeder Pipe in a Pressurized Heavy Water Reactor
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Abstract
One of the recent safety issues in the pressurized heavy water reactor (PHWR) is the cracking of the feeder pipe. Because of the limited accessibility to the cracked region and a high dose of radiation exposure, it is difficult to inspect all the pipes with the conventional ultrasonic method. In order to solve this problem, a long-range guided wave technique has been developed. A computer program to calculate the dispersion curves in the pipe was developed and the dispersion curves for the feeder pipes in PHWR plants were determined. Several longitudinal and/or flexural modes were selected from the review of the dispersion curves and an actual experiment has been carried out with the specific alignment of the piezoelectric ultrasonic transducers. They were confirmed as L(0,1)) and/or flexural modes(F(m,2)) by the short time Fourier transformation(STFT) and were sensitive to the circumferential cracks, but not to the axial cracks in the pipe. An electromagnetic acoustic transducers(EMAT) was designed and fabricated for the generation and reception of the torsional guided wave. The axial cracks were detected by a torsional mode(T(0,1)) generated by the EMAT.
참고문헌 (4)
- "Ultrasonic Waves in Soild Media" (1999), Cambridge University Press
- "Review of Progress in Quantitative NDE", pp.157~ (2002), American Institute of Physics
- "Signal from a bent pipe with no defect Signal from a notch of 10% of the wall thickness of the bent pipe Signal from a notch of 20% of the wall thickness of the bent pipe Signal from a notch of 40% of the wall thickness of the bent pipe Torsional mode guided wave signals from the axial notches of the bent pipe" (2001)
- "Review of Progress in Quantitative NDE", 16 (1997)