PWR steam generator tube integrity program. FY81 progress: leak rate studies on laboratory SCC steam generator tubes

The Steam Generator Tube Integrity Program is part of NRC research efforts concerning primary system integrity. Past programmatic activity has involved fabrication of machined or chemicaly induced defects in Inconel 600 steam generator tubing simulating service defects. These specimens were subsequently burst or collapse tested at steam generator operating temperatures and a determination made of remaining mechanical strength. Data evaluation allowed development of mathematical formulae relating defect type and size to remaining tube integrity. Eddy current data taken on the laboratory produced defect specimens then allowed development of certainty bands about plots of defect size versus remaining tube integrity. These certain bands reflect the ability to accurately size a particular defect using single or multifrequency eddy current techniques in the laboratory