FEM comparisons between RF-ECT signals in quasi-static or transient and linear or nonlinear regimes: ECT probe speed effect for in-service inspection of magnetic SG tubes in FBR

Abstract

Two-dimensional axis-symmetric finite element method (FEM) simulations are conducted to study remote field eddy current testing (RF-ECT) in ferromagnetic steam generator (SG) tubes for fast breeder reactors (FBR). The present work investigates a combination of quasi-static and transient analysis with both linear and non-linear material properties. Two FEM codes are employed: a commercial one based on COMSOL and a 2D-FEM code developed in-house. Both codes are used to evaluate the influence of the speed of the ECT probe during in-service inspection of SG tubes at a low excitation frequency. As a result, the maximum error in SG tube defect detection when using the classical linear and quasi-static approximations is obtained.