Tome Architecture and management of a geological repository - Andra

1 – Study approachSome studies were common to both projects, primarily the waste package aspects, whose results havebeen used by both projects.The "Dossier 2002 Granite" presented a preliminary overview of the designs and research about thepossibility of a repository in granite medium.The Dossier 2005 Granite draws on the conclusions of many studies carried out since 1991.Accordingly it aims to assess the assets of granite medium for the disposal of High-Level Long-Livedwaste.1.2 Andra’s research programme on disposal in a granite formation1.2.1 A generic study approachAndra’s study approach consists of identifying the major issues relating to disposal in a granitemedium in order to assess the assets of granite medium for a repository and to check that granitemedium is not ruled out. It also aims to study the technical options that would ease repositoryadaptation to a specific French site.Accordingly, understanding of the long-term behaviour of a repository and safety assessments aredecisive in defining the generic characteristics of a repository adapted to the variability of Frenchgranites.The research programme comprises four complementary areas of study, incorporated in an iterativeapproach:- the granite medium studies involve both improving understanding and modelling of the mediumand analysing the variability of the properties of French granites;- the design studies for a generic reversible disposal system are based on granite-specific elements,primarily safety considerations, the design of underground structures and the repository operatingand closure mode. Furthermore they are based on data common to the clay repository designproject, primarily those relating to disposal packages and materials;- the purpose of the long-term repository behaviour studies is to understand and model the thermal,mechanical, chemical and hydraulic phenomena that come into play in a granite mediumrepository, on the basis of the proposed options;- lastly, safety analyses aim to identify the major factors of repository performance in granite mediumwith respect to the objective of human and environmental protection. They also assess the robustnessof the proposed design options.1.2.2 The support of international co-operation and mobilisation of the national scientificcommunityAndra’s programme has extensively relied on foreign studies. Indeed, Andra has taken an active partin experimentation programmes carried out in Swedish, Swiss and Canadian underground laboratories.The main themes of co-operation involved issues concerning the structuring of a granite massif and itsfracturing, survey methods, underground natural water flow and radionuclides retention capacity of therock (Figure 1.2.1).Dossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY15/228