Reactance Change at Defect in Inconel Tube With Nickel Sleeving

The metal-loss defects are partly produced in steam generator tubes by stress and heat, because steam generator tubes are used under high temperature, high pressure and radioactivity. Tube wall defects such as corrosion pits acts as stress raisers, which leads ultimately to rupture. A nickel sleeving is used for protecting the progress of metal-loss defect, but it is difficult to detect it by conventional eddy current method in steam generator tubes with nickel sleeving. So a new method is needed for detecting the metal-loss defects on the nickel sleeving steam generator tubes. In the new method, the reactance change was calculated by finite element method to detect the defects in nickel sleeving tube. The reactance amplitude calculated for the defect present in the Inconel 600 tube with nickel sleeving is well agreeable with the results measured by the fabricated probe.