The Effect of Equipment Bandwidth and Center Frequency Changes on Ultrasonic Inspection Reliability: Modeling and Experimentation Results
The purpose of ultrasonic inservice inspection (UT/ISI) of nuclear reactor piping and pressure vessels is the reliable detection and sizing of material defects. Before defects can be sized, they must first be detected. This is typically done by analyzing ultrasonic echo waveforms with an amplitude greater than a certain percentage of that of a calibration reflector such as a 10% notch . Studies performed at Pacific Northwest Laboratory (PNL)  and elsewhere [3–5] have shown that changing the components of an ultrasonic inspection system can greatly affect echo amplitude from a defect even when conventional calibration procedures are used, thus reducing the reliability of defect detection. To address this problem, ASME code  has provided tolerance levels for equipment parameters (e.g., center frequency and bandwidth) when inspection components are changed. However, some of the code requirements are based on engineering judgement and lack a strong analytical foundation. In this paper, the results of sensitivity studies performed to determine the effects of equipment parameter changes to provide an analytical basis for ASME code are presented.
KeywordsCenter Frequency Inspection System System Bandwidth Pacific Northwest Laboratory ASME Code
Unable to display preview. Download preview PDF.
- 1.ASME Section XI, Appendix III.Google Scholar
- 2.S. R. Doctor, et al., Integration of Nondestructive Examination (NDE) Reliability and Fracture Mechanics, NUREG/CR-4469, Vol. 1, pp. 6–17 (1986), avaitabte from GPO Sales Program Division of Technical Information and Document ontrol, U.S. Nuclear Regulatory Commission, Washington, D.C. 20 5.Google Scholar
- 3.E. Borloo, F. Lakestani, and F. Merli, PISC II - Parametric Study on the Effect of UT Equipment Characteristics (EEC) on Detection Loca-tion and Sizing, PISC III Report No. 10 - Final Report ( 1988j, available from Commission of the European Communities, Joint Research Center, Ispra, Italy.Google Scholar
- 4.D. E. MacDonald and S. M. Walker, Effects of Ultrasonic Equipment Variations on Crack Length Measurements, EPRI NP-5485 (1987), available from Research Reports Center, P.O. Box 50490, Palo Alto, CA 94305.Google Scholar
- 5.G. J. Posakony, Material Evaluation, 44, pp. 1567–1572 (1986).Google Scholar
- 6.ASME Code Case N-409, Revision 1.Google Scholar
- 7.E. R. Green and G. A. Mart, in Review of Progress in Quantitative Nondestructive Evaluation ( Plenum Press, New York, 1989 ), Vol. 8B, pp. 2259–2266.Google Scholar
- 8.C. B. Scruby, K. R. Jones, and L. Antoniazzi, Journal of Nondestructive Evaluation, Vol. 5, Nos. 3 /4, pp. 145–156 (1986).Google Scholar
- 9.G. F. Miller and H. Pursey. in Proceedings of the Royal Society, pp. 521–541 (1953).Google Scholar
- 12.K. F. Graff, Wave Motions in Elastic Solids (Ohio State University Press), pp. 311–343 (1975).Google Scholar
- 13.R. K. Chapman, Ultrasonic Scattering from Smooth Flat Cracks: An Elastodynamic Kirchhoff Diffraction Theory (Main Report), CEGB Report NWR/SSD/84/0059/R PWR/RCC/MWG/P(84)378 (1984).Google Scholar