Detection of Multiple Flaws in Steam Generator Tubes of PFBR Using Ultrasonic Guided Waves

摘要

An ultrasonic guided wave-based methodology is developed for the detection of multiple flaws in steam generator tubes of the prototype fast breeder reactor. To this end, axisymmetric longitudinal mode (L(0,2)) at the frequency of 250 kHz is selected using dispersion curves based on its modal nature. It is observed that L(0,2) at 250 kHz detects multiple defects such as circumferential, axial, and partial pinholes and combination of them lying in the same line of sight with good sensitivity. Then, 3D-finite element (FE) simulations with circumferential defects are performed to understand the shadowing effect of one circumferential defect by another in its vicinity. FE results show that detection sensitivity of one circumferential defect behind another circumferential defect is affected and the amplitude reduction turns out to be around 4.7 dB.