Austenitic and Bi-Metallic Weld Inspection I Inspection of Dissimilar Metal Welds in Nozzles using Ultrasonic Phased Array and Eddy Current - Robinson Nuclear Power Plant

IHI Southwest Technologies (ISwT) provided Reactor Coolant System, Hot and Cold Leg Nozzle examinations in accordance with MRP-139, “Materials Reliability Program: Primary System Piping Butt Weld Inspection and Evaluation Guideline,” at the Robinson Nuclear Plant. During this outage volumetric inspections were performed using ultrasonic examination techniques qualified to meet the requirements of Appendix VIII to ASME Code, Section XI. ISwT performed these examinations using a Performance Demonstration Initiative (PDI)qualified phased array procedure. The phased array techniques allowed the use of multiple examination angles, generated by a single search unit to improve both detection capability and efficiency at the same time. Examinations were performed in four directions for detection of flaws both parallel and transverse to the weld using a beam angle range from 60-88 degrees. The 1.5MHz phased array probes and beam angle range were selected by ISwT specifically for this application to allow efficient detection in the inner 1/3T examination volume of the weld. Based on the number and orientation of detected indications, eddy current (ECT) examinations were also applied during this outage. To support these ECT examinations, ISwT teamed with Southwest Research Institute (SwRI ® ) to develop an ECT technique for surface exams of dissimilar metal welds in nozzles. The technique was demonstrated on stainless steel plate specimens with EDM notches and on a welded EPRI nozzle mockup with tight surface flaws. These results provided confidence that the technique was robust and could successfully detect surface flaws in welds with a good signal-to-noise ratio and with minimal response from the weld or clad material. Exams were performed on four nozzles at the Robinson Nuclear Plant using the ISwT Advanced Nozzle Tool; these exams covered areas shown to be of potential interest from ultrasonic inspections performed with the same tool. The purpose of this paper is to provide an overview of the use of both NDE methods and how they complimented one another during the Robinson Nuclear Plant outage during the fall of 2008.