Utilisation d'une technique multibond pour la detection de fissurations sur des tuyauteries de chaufferies nucleates embarquees

摘要

After the cracking by thermal fatigue problems met on nuclear civil reactor, the qualification of the non destructive examination of some parts of the defense nuclear reactor in submarine have been asked. The specificity of the nuclear navy reactor leads to examine small diameter pipes with limited accessibility: the pipes in austenitic steels have low diameters and thicknesses and have many curvatures. A specific multiskip ultrasonic technique have then been applied. The qualification have been made on samples with electro-eroded notches. The idea is to send the waves along the pipe or round the pipe. This wave can then be reflected by some defects. This technique allows to quickly scan a pipe, without having to scan all the surface of the pipe. It allows only detection : characterization still needs half skip examination. This methodology is then applied onboard.