The effect of an austenitic weld to probability of detection of ultrasonic inspection

Ultrasonic testing is an important tool to inspect the structural integrity of pressurized components in nuclear power plants during in-service inspection and more importantly, which size is the largest flaw that will probably get missed in the inspection. This in turn gives valuable in-formation to determine the most effective method for different situations. Probability of detection (POD) curves are used to determine these probabilities. However, these POD curves require a lot of data points in order to be reliable, thus producing these curves has been relatively expensive. This is why simulation tools have been used to reduce costs and reduce the amount of physical test pieces. The aim is to study how much a simulated POD curve will change according to the flaw loca-tion in austenitic stainless steel weld when inspecting with a linear phased array probe and com-pare these probabilities with each other. The results are verified by using measured results from 316L austenitic stainless steel specimen with four EDM notches machined near and in the weld. The decibel drop between the flaw in front of the weld and behind the weld was measured around 16dB. This probability change is useful to take into account in situations where the weld can only be scanned from one side and the flaw resides behind or within the weld.