Architecture and management of a geological repository - Andra

5 – Repository ModulesFigure 5.3.9Yucca Mountain project disposal concept (USA)• Comparison of spent fuel disposal conceptsThe ANDRA concept chosen for this feasibility study has a point in common with all the foreignprojects, at least in a saturated medium: the presence of a swelling clay engineered barrier. The onlyproject which does not use an engineered barrier of this type, the Yucca Mountain project, is in a desaturatedformation.Under the Belgian (SAFIR 2) and Swedish and Finish (KB3-V) concepts, the swelling clay buffer ispositioned at the time that the cell is constructed. The package is only placed in the repository oncompletion of this operation, similarly to the ANDRA concept described.However, the Swiss concept is based on the principle of a construction operation combined with theplacing of the package in the repository: the swelling clay buffer is positioned after each package hasbeen placed in the repository; when the packages are completely surrounded by bentonite, a newpackage is put in place. This concept has the advantage, compared with the ANDRA concept, ofavoiding the use of a metal sleeve. However, it has the disadvantage of requiring simultaneous “civilengineering” type operations and radioactive nuclear material handling operations At this stage of thestudies, ANDRA preferred to dissociate the construction operations from those involving the handlingof radioactive materials.The new Swedish/Finnish concept currently under study (KBS3-H) is an supercontainer type concept.It has the advantage of being able to prefabricate in surface facilities an engineered barrier continuumaround each package but makes retrieving the packages more complex. In fact, unlike the ANDRAconcept in which, during the first stage (before sealing of the cell), the packages can be retrieved in thesame way that they were positioned, the “supercontainer” concept involves the development of specialprocedures for retrieving packages.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM238/495