Ultrasonic inspection of the spherically shaped perforated areas of light water reactor pressure vessels

The development is described of an ultrasonic system which will test the areas close to the cladded inner surface between the nozzles in the bottom of boiling water reactor pressure vessels and at the top of pressurized water reactor pressure vessels. The technique uses the angle or corner effect in a single probe operation from the outside. A main problem found with this method was the strong backscattering of ultrasonic energy from the austenitic cladding. By varying the frequency, crystal area and angle of incidence used, optimum values for these parameters have been determined for this application. (author)