Architecture and management of a geological repository - Andra

9 – Nuclear operating resources in the repositoryAndra has conducted another test using a full-scale prototype in terms of the diameter as part of theESDRED European project.On the other hand, in the case of the CU2 package, the weight is compatible with the technique ofpushing by sliding. The diameter of the CU2 package is at the lower limit for using air cushion cells.Finally, as in the case of the CU1 packages, the incorporation of wheels would complicate themanufacturing process and increase the length of the package.Consequently, the comparison of the three options presented above led to us favouring the air cushiontechnique for type CU1 packages and the technique of pushing by a robot with jacks for type CU2packages. This latter principle being similar to that adopted for C packages, it will not be described inthe sections below.9.3.4.2 Description of the equipment for installing type CU1 packagesThe equipment studied using the chosen air cushion technique consists of three parts: a mobile robotcalled "air cushion transporter", fixed equipment mounted on the chassis of the transfer transfer caskand fixed equipment installed at the head of the cell. The air cushion transporter is connected to thefixed equipment on the transfer cask by means of an umbilical cable. The fixed equipment at the headof the cell contributes with the transfer cask to the radiological protection of personnel.• The air cushion transporterThe air cush ion transporter illustrated by Figure9.3.18 consists of two components connected toone another by a coupling system: an electrictrolley and a cradle bearing the air cushionmodules.The air cushion transporter fulfils three functions:keeping the package floating, pushing the floatingpackage and moving the empty air cushiontransporter.The first function (keeping the package floating onan air cushion) is ensured by a structure bearingFigure 9.3.18 Air cushion transporterthe air cushions called the "cradle". This cradle ispositioned under the disposal package in the spacebounded by rails of 50 mm thick fixed to the cell sleeve. It comprises a dozen standard air cushionmodules operating at a pressure of about 4 bars. These air cushions create an air layer that keeps thepackage floating.Each air cushion module consists of a ring-shaped, inflatable rubber apron curved to the diameter ofthe disposal package. The air blown in first inflates the rubber apron that expands to a height of about20 mm then lifts the load of its supports 133 . The air then escapes to form a very thin air mattress thatraises the load by a few tenths of a millimetre. The package is then in a state of suspension and can bemoved with very little effort. This principle is illustrated by Figure 9.3.19.133 An intermediate sliding plate is placed between the packages and the air cushion. This stainless steel “plate” has a very smooth surfaceto obtain maximum effectiveness from the air cushion..DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM360/495