A remark on data for defects used in probabilistic analyses of failure of nuclear pressure vessels

Abstract

In a fracture mechanical probabilistic analysis of the failure of nuclear pressure vessels, data are needed for the presence of defects that may have escaped detection during non-destructive examination. At present such statistical data can be obtained only by subjective estimates. A review has been made of the data on the effectiveness of defect detection on which the most widely cited probabilistic analysis of the safety of nuclear pressure vessels has been based. It seems justified to use considerably lower values for effectiveness. Correspondingly, the calculated probabilities for failure of nuclear pressure vessels should be raised. Consequently, this type of failure would become of greater concern than presently assumed considering the risks associated with nuclear power plants.