A major safety issue: ensure the integrity of steam generator pipes

The steam generator is a pressured vessel equipment that allow the thermal transfer between the main and the secondary's principals circuit of the nuclear plant. It has a safety issue too since it is a bypass between the second and the third barrier of confinement. The steam generator bundle tube is concerned by numerous active mechanisms of degradation, and is controlled regularly according to a specific program of maintenance. This paper describes the main mechanisms of degradation, and the techniques, probes and strategies to treat them. Due to the alloy used for the fabrication of the steam generators tubes, it is necessary to replace some of the older EDF's steam generators, and to take actions to preserve the integrity of those equipments in waiting steam generators with more stress corrosion cracking resistant components. (author)