Aspects regarding the steam generator tube plugging at the support plate entrance using a high speed mechanical deformation procedure

摘要

The CANDU 6 NPP was designed to allow the post-decontamination evaluation of the steam generator tube wall thickness. It is conducted using Eddy currents while providing data regarding the defects' depth evolution, length and degradation volume, and also identifies new surface defects, while comparing them to the specified values. This article presents two tube plugging techniques using the same technique: plastic deformation by electrohydraulic shock based on the action of the pressure wave peak generated by a plasma stream created by the instant vaporization of a fuse and its surrounding water volume inside an enclosed chamber bounded by the expansion chamber walls. The process can be controlled by choosing the fuse and its discharge energy. Their implementation increases the life span of the connection; the first applied technique shortens the time of intervention by eliminating the lengthening of the tube mandrel inside the support plate.