Objectif For the long term performance of an HLW repository, lt lS essential to backflll and/or seal the shafts and galleries so that they cannot act as preferential pathways for the m1gratlon of water, gas or radionuclides. Therefore, we will demonstrate the feasibility of an in situ seallng on a representative scale. Since about 10 years the use of highly compacted bentonite and hydraulic cements for sealing and backfill has been studled on laboratory and ln sltu scale. In granite (STRIPA project), large scale sealing tests have been performed successfully. In clay, only relatlvely small scale experiments have been performed (BACCHUS experlments) in the framework of the development of thermo-hydro-mechanical models. They were essentially related to the study of the near field and its associated temperature effects. The objectlves of the proposed project are: - to demonstrate the feasibility of the backfilling and sealing of a shaft on a large scale (1.4 m diameter shaft) in the HADES underground research facility - to demonstrate the effectiveness of the sealing of a borehole - to demonstrate the resistance of the seal against gas and water pressure - to demonstrate that a low permeability shaft seal can avoid preferential migration of water and gas even through the excavation damaged zone of the host clay formation - to validate models for the calculation of gas and water transfer through the sealing system, takink into account geomechanical effects. The project simulates the sealing of a shaft that will be situated outside the radiatlon and heat field of an HLW or spent fuel repository. The functioning of a sealing material will be demonstrated. The main sealing material option is a mixture of high density bentonite pellets with bentonite powder. This sealing material will be optimized to obtain the best balance between saturation time, swelling pressure and hydraulic conductivity. The possibility of the use of precompacted clay blocks is also considered as a reserve option. The transfer of water and gas will be studied. Geomechanical effects will be included for the understanding of the fluid transfer and the design of the experiment. To study the influence of the in situ stress conditions around a gallery on the transfer of water and gas, a preliminary small scale in situ test will be done. In this project a procedure for the production and installation of a shaft seal will be developed. The transport and geomechanical parameters of the candidate sealing materials in saturated and unsaturated conditions will be measured. These parameters with the results of the small scale borehole sealing experiment, will allow for the calibration and further development of hydro-mechanical codes. The sealing system for the 1.4 m diameter shaft ln the HADES underground research facility will be designed to allow the validation of the hydro-mechanical codes. Water and gas injection experiments will be done on this sealing system to prove its performance. Programme(s) EAEC-NFS 2 - Specific research and training programme in the field of nuclear safety and safeguards, 1994-1998 Thème(s) 030202 - Backfilling and sealing of repositories Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur BELGIAN NUCLEAR RESEARCH CENTRE Contribution de l’UE Aucune donnée Adresse 200,Boeretang 200 2400 MOL Belgique Voir sur la carte Coût total Aucune donnée Participants (5) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Agence Nationale pour la Gestion des Déchets Radioactifs France Contribution de l’UE Aucune donnée Adresse 1-7,Rue Jean Monnet 92298 Chantenay-Malabry Voir sur la carte Coût total Aucune donnée Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas Espagne Contribution de l’UE Aucune donnée Adresse 22,Avenida Complutense 22 28040 Madrid Voir sur la carte Coût total Aucune donnée Commissariat à l'Energie Atomique France Contribution de l’UE Aucune donnée Adresse Ctr Etudes de Saclay 91191 Gif-sur-Yvette Voir sur la carte Coût total Aucune donnée EMPRESA NACIONAL DE RESIDUOS RADIOACTIVOS S.A. Espagne Contribution de l’UE Aucune donnée Adresse 7,Emilio Vargas 7 28043 MADRID Voir sur la carte Coût total Aucune donnée INTERNATIONAL CENTRE FOR NUMERICAL METHODS IN ENGINEERING Espagne Contribution de l’UE Aucune donnée Adresse S/N,Gran Capitan s/n, Campus Norte UPC, Edificio C1 08034 BARCELONA Voir sur la carte Coût total Aucune donnée