Architecture and management of a geological repository - Andra

11 – Operational SafetyTable 11.5.1Main characteristics of the packages and transfer transfer casksPrimary package(internal temperature)Specific data related to thetemperature conditionsDisposal packageTransfer transfer caskMaterialsThickness(mm)B2.1 173bituminised sludge(ambient temperature)softening at 40°Cflash point at 230°Cspontaneous combustion at350°CConcrete package(with 4 primary packagesin vertical position)Steel180 to 220Thermalshield 174 20CSD-Vvitrified wastes(64°C at waste core)Crystallisation of the glass :450°CMetallic overpack(with a CSD-V packagein horizontal position)Internal steelNeutrophageExternal steel200 to 230140 to 15020CU1spent fuels UOx(87°C at centre ofassembly)Embrittlement of the fuel cladabove 500°CMetallic container(with 4 spent fuels inhorizontal position)Internal steelNeutrophageExternal steel701202011.5.1.1 Definition of a fire scenarioThe vehicle used to transfer the transfer casks is a self-propelled electric transport vehicle on tyres.The reference fire studied is located in the underground installations. It was defined from the specificcharacteristics of the vehicle and the recommendations of the Road Tunnel Study Centre (CETu) ; itcorresponds to a fire with a heat rating of 15 MW for a duration of one hour (cf. section 11.4).The fire breaks out and spreads in a connecting drift with a ventilation rate under normal operation ofapproximately 30 m 3 /s, which increases to 50 m 3 /s after the smoke removal system is started.11.5.1.2 Data related to the simulation studiesThe simulation uses a finite elements method for an elaborated description of the temperaturedistribution taking into account the non linearity of heat exchanges.The heat produced by the fire is transmitted from the source of the fire to all the components of thetransport vehicle and the transfer cask by a convective flow and a radiant flow representing 2/3 and1/3, respectively, of the total heat rating of the fire 175 :- The convective rating appears in the fumes emitted by the fire source. They are mixed with the aircirculating in the drift, they envelop the transfer cask and exchange heat with it,- The radiant rating is related to the radiation generated by the fire source. It is applied differentlydepending on the transfer cask’s geometric form. In the case of cylindrical transfer casks (C wasteand SF packages), it is uniformly applied to the vehicle’s flat bed, the transfer casks’ frame andtheir lower half cylinder. For parallelopiped transfer casks containing B waste packages, half ofthe rating is applied to the lower surface in contact with the vehicle’s flat bed and half to the sidesurfaces.173 The bituminised sludge package was retained among the various B waste packages because it is the most risky in terms of ignition.174 For some B waste packages (B4, B5), a neutrophage material whose characteristics would allow it to play the role of a thermal shield isto be used like for the C and CU waste packages.175 This breakdown corresponds to the recommendations of the CETu (Road Tunnel Study Centre) for a fire in this type of vehicle.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM465/495