Steam-generator tube testing: Automated defect detection and documentation, analytical measurements

The steam generator tubes as parts of the reactor-coolant pressure boundary have to undergo in-service inspection at regular intervals, for which purpose the eddy-current inspection method is used. On account of the frequently large scope of inspection and the multitude of indications, a procedure has been developed for the automated detection and documentation of defects. Defect detection is performed on-line with the aid of an analog network. False indications are suppressed by multifrequency gating. The gated and frequency-filtered eddy-current signals are scanned by discriminators. Above-limit signals trigger the generation of computer plots, which are evaluated by eddy-current inspectors. (orig.)