Ultrasonic Testing in Nuclear Plants

Abstract

The approach for nondestructive testing inspections in nuclear power plants differs significantly from nonnuclear industries. In most industries, inspections are planned and specified by owners or insurance companies. Nuclear plant inspections are, however, regulated and must follow certain processes, regulatory requirements, and required codes. Codes classify components and specify inspection methods, coverage, and inspection intervals. With regard to ultrasonic testing (UT), there is a broad range of applications for nuclear plant components. Applications vary from simple corrosion/erosion scanning to more complex techniques that require UT of difficult-to-inspect materials. These include dissimilar metal welds of materials such as stainless steel, nickel alloy, and cast stainless steels. In addition, UT inspection can include tests of complex geometries such as nozzles and turbines. Furthermore, due to the nature of the nuclear plant operation, the inspection processes must be demonstrated to validate reliability and qualify equipment and personnel. Finally, this article highlights the importance of using notches as calibration reflectors when using refracted longitudinal waves and large aperture phased array probes to improve resolution.