After recent events in NPP, EDF/DTG re-examined its existing inspection strategy of Flow Accelerated Corrosion (FAC) for the secondary loop of its NPPs.
Welds, which are not yet taken into account by the predictive software BRT-CICEROTM, have been identified as a weak point. An inventory of the welds inpections and a program of metallurgical examinations on field components have been established. (seperate presentation)

The use of classical Non Destructive Examination techniques like ultrasonics or radiography is not efficient enough for the detection and dimensioning of weld root degradation. This is the reason why EDF/DTG qualified two specific inspection methods. These NDE techniques are the ultrasonic technique TOFD (Time of Flight of Diffraction) and digital radiography. The test program permitted to establish the accuracy and limits of both methods that now will be applied in the field.

Thomas KNOOK works at EDF/DTG since 1999, where he is in charge for testing and qualification of new NDE techniques related to FAC. Before he came to EDF/DTG he worked from 86 to 99 for the German utility RWE in the fast breeder nuclear power plant called Superphenix. At the SPX powerplant he was in charge for the in-service inspection of the reactor vessel and the secondary sodium loops.