Architecture and management of a geological repository - Andra

6 – Overall underground architecture6.3.2 Thermal behaviour of the repositoryLimiting the temperature in the repository is dependent on the dimensioning of the repository modulespresented in Chapter 5. The interaction between repository modules, however, leads to diffusion ofheat into the geological formations. This section evaluates the impact of this interaction and confirmsthat it is compatible with the above-mentioned objective of keeping different categories of wasteindependent.6.3.2.1 Evolution of Temperatures in and around high level waste repository modulesFor an initial period of some decades after emplacement in the repository, the temperature of a wastepackage solely results from the heat it releases and that released by packages in immediate proximityto it; this is due to the slow diffusion of heat into the geological formation. In the longer term, the areaof thermal influence of each package gradually increases. The evolution of the temperature in therepository modules therefore becomes sensitive to the relative layout of the modules.Thus, the further a module is extended and the closer it is to neighbouring modules, the longerpackages situated at the centre take to cool. Similarly, the temperature of modules situated at the coreof the repository zone will take longer to drop than that of the modules situated around the perimeter.The following figures show the evolution of the temperatures on the scale of the C waste repositoryzone. This evolution has been calculated by projecting in time the thermal simulations produced bythree-dimensional finite elements presented in Chapter 5.Figure 6.3.2Horizontal evolution of the temperatures in the c waste repository zone,(scenario s1a, disposal of the waste after 60 to 70 years of temporary storage)Figure 6.3.3Vertical evolution of temperatures around the c waste repository modulesDOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM265/495