Performance comparison of phased array transducers for inspection of dissimilar welds on nuclear reactor components

Abstract

Abstract Trimetallic weld joint of steam generator is crucial and most critical component of Prototype Fast Breeder Reactor (PFBR). Ultrasonic examination of trimetallic welds are more challenging due to the coarse anisotropic grain structure of the weld metal and the mismatch of the acoustic impedance at the weld metal interface, which contributes to increase scattering, sound beam deviation and distortion, reflection and refraction of the incident sound field. This paper presents a comparative study on phased array ultrasonic examination of dissimilar weld joints (P91 – Alloy 800) using linear array (LA) and dual matrix array (DMA) transducer. Prior to the experimental investigations, wave propagation through the dissimilar weld joint and the defect sensitivity is understood by carrying out simulation based on ray-tracing and semi-analytical methods. Weld joint sample with artificial defect such as lack of side wall fusion was fabricated and studied using both transducer of Phased Array Ultrasonic Testing (PAUT).