Modelling of Phased Array Ultrasonic Inspection of a Steam Generator Dissimilar Metal Weld

Phased array ultrasonic techniques (PAUT) are more and more used for inspection of the primary circuit of nuclear power plants in order to detect defects such as stress corrosion cracking (SCC) at the dissimilar metal welds (DMWs) between the main pipe lines and large components such as the pressure vessel, steam generators and pressurizers. Nevertheless, disturbances such as beam splitting and skewing may occur due to the anisotropic and inhomogeneous properties of the welding material. These disturbances affect the detection, localization and sizing of possible weld discontinuities. Simulation tools can help to understand these physical phenomena, optimize ultrasonic testing. Since strict safety requirements are leading to increased demands for the inspection of such components, a research task called MAPAID has been dedicated under the umbrella of “NUGENIA+” FP7 project to model and validate PAUT techniques for inspection of DMWs of nuclear power plants. As a part of the task, this study presents the phased array ultrasonic inspections and ultrasonic simulations of steam generator DMW. The testing has been recently developed in the CIVA in order to determine the index distances regarding the given orientation artificial defect analysis and the incident angles for longitudinal and transversal tests. By comparing the experimental and simulation tests results, conclusions can be drawn to quantitatively assess the contribution of phased array techniques to improved NDE performances of such parts, as well as the ability of simulation to help for design, optimization and interpretation of such inspections.