Eddy-current inspection for steam generator tubing program. Annual progress report for period ending December 31, 1981

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 specimens that are necessary to calibrate the instrumentation for all the possible combinations of positions of flaws, tube supports, and probe coils, a computer-controlled automatic positioner has been constructed and used. An advanced microcomputer has been designed, constructed, and installed in the instrumentation to control the examination and provide real-time calculations of the desired properties for display and recording during the scanning of the tube