Defect detection and sizing: USA perspective

Nondestructive testing methods are widely used for the detection, location, characterisation and sizing of defects in a multitude of components and structures. The success of these efforts is attested to by the satisfactory service of the tested articles. The growth of the technology of fracture mechanics analysis, and the need to evaluate the effect of the defect on the serviceability of the component has placed increased emphasis on reliability of nondestructive testing. There is very little factual data on the reliability of defect detection, accuracy of sizing, characterisation, and sizing of defect. This paper will discuss the aspects of ultrasonic methods as related to the inspection of a nuclear component. Data will be presented for both piping systems and nuclear reactor pressure vessels. The principal problem appears to be accuracy of defect sizing and this paper will discuss research underway such as holography, adaptive learning network, the synthetic aperture focusing technique, phased arrays, and acoustic imaging; it appears that certain of these research efforts have a potential for sizing accuracy equal to the needs of current fracture mechanics technology. (author)