The mock-up Ophelie: A Demonstration for HLW disposal

The waste management agency NIRAS/ONDRAF detailed the first design for the disposal of vitrified HLW (high level radioactive waste) in the early 1990s. It consisted of a network of disposal galleries in the Boom Clay formation, the reference host formation in Belgium. In such gallery the waste packages were positioned in a central liner. Bentonite based blocks backfilled the space between the central liner and the gallery lining. A large scale in situ test called PRACLAY will simulate a section of such a gallery in the HADES (High Activity Disposal Experimental Site) underground research facility. During the preparation of this test, the principal investigators realised that several aspects needed to be worked out in detail further through a large scale mock-up at the surface. EIG EURIDICE (an economical interest grouping between SCK-CEN and NIRAS/ONDRAF)managed this mock-up test, called OPHELIE; it consisted in the design, operation and analysis of the mock-up. Other partners in this research project were CEA, UPC, EDF, and ANDRA. Realising the mock-up test has enabled us to study the feasibility of the different technical aspects of the repository design, such as manufacturing and installation of the backfill material in preparation of the PRACLAY In Situ Test. Running the OPHELIE mock-up test then has revealed the performance and the thermo-hydro-mechanical behaviour of the different components, as well as the robustness and reliability of the monitoring equipment. An extensive analysis of the components (backfill, instrumentation, metals) during and after dismantling has completed the information obtained during the previous stages