On the reliability of ultrasonic testing of welded joints in NPP components

Programs and techniques of investigating the reliability of methods of ultrasonic testing (UT) of welding joints for NPP equipment are briefly described. The investigations are performed both in the USA and the NEA member-countries. Dependences of the defect detection confidence probability on the size of defects, and the probability of accurate localization of defects on the spread of the defect sizes are presented. The preliminary analysis of results obtained after statistic processing has shown a high efficiency and reliability of non-destructive UT thick-walled steel elements for determining the position and geometric parameters of defects