Architecture and management of a geological repository - Andra

Figure 10.4.10C Cell at end of operation• Prior serviceability inspection process of the cell head sectionThermal modelling demonstrated that the temperature of the drift walls does not exceed the 60°Cregulatory threshold, even when taking into account ventilation shutdown immediately after loadingall of C or spent fuel repository zone. Where ventilation in the module or disposal area concerned hasbeen shut down, it is necessary to restart it prior to performing any work for the purpose of reachingregulatory ambient air temperature values. These values are between 26 and 32°C depending on thetype of the work station and air relative humidity conditions. The duration of such a ventilationnotification is roughly estimated at several hours.For safety purposes, it is then possible to check that the atmosphere in the cell is in compliance withthe expected state. This check may be performed via inlets provided in the shielded trap door orleaktight cover.If the shielded trap door is no longer inplace, the leaktight cover replacing it is removed to perform avisual and dimensional inspection of the cell head section. To do this, the operators are protected fromradiations by the metal radiological protection plug. The purpose of the inspection is to check thecondition of the temporary sleeve and the handling mark of the metal plug. The functional clearancebetween this plug and the sleeve is also checked.These visual, dimensional and temperature inspections may be conducted using standard equipment. Itmainly includes cameras, laser optical appliances and thermometers.After these inspections, the cell is re-equipped with a shielded trap door for fitting the transfer caskand handling equipment.Now the transfer cask is ready to permit the package retrieval process. The time for reconditioning thecell is estimated at a few days.• Package retrieval processThe required retrieval equipment is similar to the equipment used to install the packages. It consists ofa transfer cask fitted with fixed equipments and a moving robot. The fixed equipments include a winchand a hydraulic power unit.The specific components of this equipment with respect to the disposal equipment are mainly the robotand associated winch. Even though the robot pushing C waste packages or the overhead lifter for spentfuel packages can be used to withdraw packages, use of more suitable equipment may be consideredfor this particular purpose.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM427/495