Results of a round robin test on NDT methods for austenitic pipe welds in nuclear power plants

A research programme sponsored by the German utilities (VGB - Technical Association of Large Power Plant Operators) was performed at MPA Stuttgart between 1993 and 1999. Objectives of the programme were to gain information on the feasibility of evaluation methods and on influencial parameters on the results of the non-destructive testing. Circumferential welds of typical austenitic pipes or pipe-elbow connections in nuclear power plants were investigated in a round robin test. Teams of different NDT vendors and research institutes performed blind tests using ultrasonic testing, radiographic testing, and digital radiographic testing. The test pieces consisted of cut-out austenitic weld specimens containing service induced cracks. After the non-destructive testing metallographic analysis was performed in order to verify the NDT results. With these data the performance of the NDT could be assessed using POD and ROC curves.