In-situ eddy current monitoring under high temperature environment

Abstract

The feasibility of in-situ Eddy Current Monitoring (ECM) under high temperature environment is discussed. For the purpose, an ECM experiment was conducted at a System Safety Benchmark Facility (SSBF), which was designed and constructed for assessing the crack growth behavior of welded pipes in a Boiling Water Reactor (BWR) environment. The target for the monitoring was a large-scale pipe specimen made of austenitic stainless steels 304, 304L and 316L, connected by weld joints of nickel based alloy 182 within the SSBF. Slits were prepared at the Heat Affected Zones (HAZs) and weld lines from the inner surface of the pipe specimen. Eddy Current Testing (ECT) probes were arranged on the outer surface of the pipe specimen at the positions where the slits had been introduced. After exerting the load, it was observed that the ECM experimental signals changed. Subsequently, the numerical simulation of eddy current signals based on the experimental conditions was carried out. As a result of comparison between experimental and numerical eddy current signals, it is shown that the in-situ ECM system makes it possible to observe crack propagation in a BWR environment.