Finite Element Modelling of a Pulsed Eddy Current Probe for Steam Generator Tube Inspection

Steam generator (SG) tubes in CANDU ® nuclear reactors can lose efficiency in the presence of corrosion and its by-products. Current inspection methods used in SG tubes have limited capabilities to determine the condition of surrounding support structures. Condition monitoring of support structures could help direct maintenance activities and thereby increase SG tube lifetime. Pulsed eddy current (PEC) has been proposed as a method to non-destructively determine the presence of defects in support structures. COMSOL Multiphysics was used to study a PEC probe configuration for measurement of SG tube-to-support structure gap, offset and relative tilt. Basic analytical models and experimental results were compared with COMSOL finite element (FE) modeling results. Analytical and FE models were in excellent agreement. FE, which is capable of modeling the more complex electromagnetic interactions between probe, SG tube and support structure, provided an excellent qualitative description of experimental results.