Architecture and management of a geological repository - Andra

9 – Nuclear operating resources in the repository9.2.3.2 Principle of the surface/bottom transferThe shaft equipment operates entirelyautomatically. When a transfer cask descends noone is present in the cage, nor in the surface andbottom airlocks.The introduction of a transfer cask in the shaftcage at the surface and its extraction at theunderground installations level is conducted bysimilar vehicles. These vehicles, running ontyres, are like a fork-lift truck (Figure 9.2.6)The vehicle lifts up the transfer cask, thentransfers it from the storage building towards theshaft through an airlock, and places it in the cageon the lateral supports.The transfer cask is then sent down in the cage ata nominal speed of 1m/s. The time taken todescend to the bottom is about 10 minutes taking Figure 9.2.6 Principal of loading andinto account the acceleration, deceleration and unloading the casks in the cagestopping times.The transfer cask is removed at the bottom using the reverse procedure to its introduction at thesurface by means of a self elevating vehicle on tyres of the same type. This vehicle picks up thetransfer cask and transfers it in the drifts to the vicinity of the disposal cells.9.2.4 The transfer of the transfer casks in the underground installationsThis section describes the procedure for transferring the protective transfer casks in the undergroundinstallations. The process described here is based mainly on a transposition of the industrial practicesused in the mining industry. It aims at minimising the dimensions of the drifts and crossing structuresand separating the process of long-distance transport from that of docking the transfer cask at the headof the cell (which requires more specific equipment).9.2.4.1 Principle of the cask transfer operationsThe operations of transferring a transfer cask from the bottom station of the packages descent shaftuntil it is docked at the head of the cell is the most specific part of the transfer cycle of the disposalpackages between the surface and the underground installations. At this stage of the studies, we favoura cycle consisting of two stages.The first stage involves transferring the transfer cask from the cage in the descent shaft to theimmediate proximity of the disposal cells through a network of drifts. This transfer is conducted usinga machine called the "transfer vehicle" that is capable of transporting heavy loads over long distances.This vehicle is similar to that used at the surface for putting the transfer cask into the cage.The second stage is the docking of the transfer cask at the head of the cell. This operation is conductedusing specific equipment working over short distances. This is called the "docking shuttle".The transition from the first stage to the second therefore requires the load to be transferred from the"transfer vehicle" to the "docking shuttle". The separation of the two processes described above andthe use of two different vehicles has several advantages: the specialisation of each vehicle means thatthe cross sectional area of the docking shuttle and the length of the transfer vehicle can be reduced andalso the mechanical systems needed for docking are not unnecessarily included in the transfer vehicleand transported over long distances. Finally, the transfer vehicle does not stand idle during the stage ofdocking and unloading the transfer cask.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM342/495