Architecture and management of a geological repository - Andra

4 – Waste disposal Packages4.2.4 Manufacturing techniquesThis section details the envisageable techniques used to manufacture the disposal packages based onexisting industrial analogues.Manufacture will take place in two phases. The first phase concerns the factory production of overpackcomponents; a particular aspect is the installation of sliding runners on the body of the object.The second phase includes installation of the primary package of vitrified waste in the over-pack andclosure of the disposal package by full penetration welding of its lid. This second phase is performedin a succession of shielded cells.4.2.4.1 Manufacture of the container and its lid in the factoryThe components to be manufactured are a body made of non-alloy steel (P235) equipped with ceramicsliding runners, and a lid. Various techniques can be envisaged and they have been tried and testedindustrially, for dimensions and thicknesses at least equal to those of the over-pack [50]. At the end ofa comparative analysis, two of them appeared to be particularly suitable.The first consists of forging a shell, then attaching a base. To produce the shell, an initial roughmachined blank is obtained from an ingot and then drilled. This blank is rotated on a calibratedmandrel inside the blank. It is then stamped from the outside to increase its external diameter. Forgingseals any faults in compactness of the initial ingot and produces parts with a fine structure free ofcompactness faults. This technique was used to produce a demonstration model of a spent fueldisposal container (See § 4.3.4.1). The base is produced separately, using methods such as staticmoulding, stamping, forging or cut and welded laminated sheets. The shell and base are thenassembled by full penetrations welding to form the body of the container.The second technique consists of producing the body in a single part, by drilling and drawing. Thistechnique has the advantage of avoiding welding the base. The internal cavity of the container isobtained by deformation of the metal. Drilling – drawing consists of obtaining a tube from an ingot.The ingot which is removed from the oven is hot-drilled using a drill with a vertical press to obtain theinner diameter, then drawn by rolling, using a horizontal press in an extrusion die to obtain therequired outer diameter and length (see Figure 4.2.6 and Figure 4.2.7). The part then undergoes heattreatment and is machined to achieve the final dimensions.Figure 4.2.6Ingot – Drilling - DrawingDOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM140/495