Tome Architecture and management of a geological repository - Andra

6 – C waste repository zoneIn a two phase manufacturing, the first one would be factory manufacturing of over-pack components.The second phase includes installation of the primary package of vitrified waste in the over-pack andclosure of the disposal package by full thickness welding of its lid. This second phase must be carriedout in a series of shielded cells to protect the operators from exposure to the radiation emitted by thewaste.6.3.3.1 Factory manufacturing of the container and its lidA presentation of the components to be manufactured has already been made. There are a number ofpossible techniques. They have been proven industrially for the dimensions and steel thicknesses atleast equal to those of the over-pack [48]. Andra has conducted a comparative analysis of possiblemanufacturing techniques and two of them have emerged as particularly suitable:- the first consists of forging a shell then joining a base to it. To manufacture the shell, a first blank(rough form) is obtained from an ingot, then pierced and finally forged. This technique has beenused to produce a spent fuel container demonstrator studied for the clay medium. The base ismanufactured separately. The shell and the base are then assembled by welding through the fullthickness to form the container body;- The second technique consists of producing the body in a single part, by boring and drawing. Thistechnique has the advantage of avoiding welding the base. The internal cavity of the container isobtained by deformation of the metal. Boring – drawing consists of obtaining a tube from an ingot.The ingot which is removed from the oven is hot-drilled using a boring machine with a verticalpress to obtain the inner diameter, then drawn by rolling, using a horizontal press in an extrusiondie to obtain the required outer diameter and length (Figure 6.3.2 and Figure 6.3.3). The part thenundergoes heat treatment and is machined to achieve the final dimension.Figure 6.3.2Ingot – Piercing - DrawingFigure 6.3.3Drawing operation in a die using a mandrel and a horizontal pressDossier 2005 granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY173/228