Mercury modeling for improved crack sizing in tubing

Date
1993
Authors
Shannon, Robert
Junker, Warren
Nakagawa, Norio
Behravesh, Mohamod
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Altmetrics
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Research Projects
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Abstract

The Westinghouse Science and Technology Center has successfully demonstrated that its patented mercury modeling technique provides a unique experimental bridge between tubing eddy current inspection conditions and analytical modeling efforts [1,2,3]. This approach is particularly useful for developing field inspection applications in nuclear steam generator tubing where the characterization of primary water stress corrosion cracking (PWSCC) has presented a challenge for eddy current inspection technology. Significant progress has been reported recently toward developing analytical models of the eddy current signal structure [4,5] and toward new techniques for inverting crack size from the eddy current signal structure. These models are presently limited in ability to represent real-life complexities, and they also must be experimentally validated. The mercury modeling approach permits the controlled study of an unlimited range of discontinuity morphologies and sizes, as well as steam generator structural and geometric factors. The mercury model is used in this study to investigate the effects of crack morphology on newly proposed eddy current length sizing techniques compared with current industry practices. The primary emphasis is to model cracks that more closely represent the morphology of PWSCC compared with ideal notch-like shapes. Effects of crack shape, crack face connectivity, and the presence of multiple initiation-sites are demonstrated.

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