TRANSPORT OF TWO STEAM GENERATORS BETWEEN CHOOZ A NPP AND ANDRA’S VLLW DISPOSAL SITE

Nuclear Power Plant of Chooz A was the first Pressurized Water Reactor in France, operated from 1967 to 1991. The NPP is now being decommissioned. Two on the four Steam Generators of the reactor were transported in November 2012 to ANDRA’s Very Low Level Waste disposal site. These large objects (120 metric tons each) were decontaminated prior to being transported by road as unpackaged objects. Steam Generator n° 2 was shipped under a special arrangement, as a “hot spot” was remaining within the object. Steam Generator n° 1 has undergone an additional process of decontamination and was fully in compliance with the SCO-1 criteria. This paper presents EDF’s experience with these two shipments, including: - an overview of the strong and complex process of decontamination which was necessary to reach both the Very Low Level Waste French criteria and the SCO-I criteria, as several of the 1662 tubes of these Steam Generators were plugged during the operation of the NPP ; - the determination of the nuclide vector by the means of samplings on the tubes bundle ; - the description of the measurement phase, and how it was possible to determine the values of the contamination on the inner surfaces of the Steam Generators by gamma detection and numerical methods ; - the design of the tie-down of these large objects onto the vehicles ; - the overall transport safety analysis, and the technical and operational measures taken for the safe shipment of Steam Generator n° 2 under a special arrangement, as it was not possible to perform drop tests, nor to put the object into a package. It was proved that such large objects can be transported as unpackaged SCO-I, providing that they undergo a long and complex process of decontamination and characterization.