In-service inspection of the primary circuit in PWRs

The Commissariat a l'energie atomique, at the request of Electricite de France and Framatome, has developed original techniques for testing critical components of the primary circuit in PWRs. These techniques involve a very wide range of non-destructive testing methods, namely: eddy currents, in particular, with a multiple frequency device for testing steam generator pipes, studs and nuts; focused ultrasonic beams for testing all the welds of the reactor vessel and of its lid, the mixed welds of vessels and of steam generators, pressurizer lower head welds and studs from the inside; gamma radiography of the mixed welds of the vessel; televisual examination and examination by sweating of the rust-proof lining of the vessel and of its lid together. To these tests should be added acoustic emission studies which have been carried out during the hydraulic trial of the primary circuit and which are continuing at present during operation. These techniques are already in use both on reactors which have been in operation and on those which have not yet gone critical. So far, the two 900-MW Fessenheim reactor units and the Chooz reactor have been inspected successfully. (author)