Artificial flaw detection with ultrasound in austenitic stainless steels

Ultrasonic testing is the main tool to inspect the structural integrity of primary circuit components in nuclear power plants (NPPs) during in-service inspection (ISI). In order to validate an inspection method and to train inspectors, reference flaws are needed. However, there are not enough real flaws available to be used for these purposes so artificial flaws must be used. Ultrasonic response from an artificial flaw must be representative enough so that it can be used as a reference flaw. Otherwise this could lead to a false result during an ISI. Unfortunately ultrasonic testing is highly dependent on the geometry of the component, the flaw type and the material in which ultrasound propagates. Therefore numerous flaws are needed to cover the probable flaw types, sizes and locations. The aim is to study artificial flaws and acquire wider knowledge on ultrasonic indications from artificial flaws in austenitic stainless steel weld and to compare them to the results from CIVA simulation. The study focuses on notches made by electrical discharge machining (EDM). EDM notches were chosen, since they represent a rough estimate of a crack type flaw and they are fairly quick and easy to manufacture.