Eddy-current inspection for steam generator tubing program. Annual progress report, December 31, 1980

Eddy-current methods provide the best in-service inspection of steam generator tubing, but present techniques can produce ambiguity because of the many independent variables that affect the signals. The current development program has used mathematical models and developed or modified computer programs to design optimum probes, instrumentation, and techniques for multifrequency, multiproperty examinations. To facilitate the extensive laboratory scanning of the matrix of specimens that are necessary to develop algorithms for detection and analysis for all the possible combinations of positions of flaws, tube supports, and probe coils, we have designed, constructed, and used a computer-controlled automatic positioner. We have calibrated the instrumentation on an array of standard samples and used these measurements to formulate the algorithms for determining the desired properties. We have outfitted a mobile laboratory, mounted in a pickup truck, and we have successfully inspected steam generator tubes at the Robert E. Ginna and Point Beach reactors.