grimsel test site research on safe geological disposal of radioactive waste The Grimsel Test Site 450 metres beneath the Juchlistock performance of geological and engi- The Grimsel Test Site is located at an alti- neered safety barriers of deep geological tude of 1730 metres above sea-level in the repositories. In addition, experiments are granitic formations of the Aar Massif. It is being conducted on a 1:1 scale and under reached via the access tunnel of the Ober- natural conditions. For example, very hasli AG hydropower plant (KWO). The small amounts of radioactive substances total length of the laboratory tunnels is are used in a radiation controlled zone to around one kilometre; the tunnel network examine the migration behaviour of these was excavated in 1983/84 using a full-face substances directly in the rock. boring machine and blasting techniques and has since been extended three times. Geology Some 300 million years ago, magmas Internationally recognised research solidified to form granitic rocks in the centre Grimsel area. New molten masses pene- More than 20 partner organisations from trated into fissures of the cooling rock various countries as well as the EU are and solidified as dyke rocks. The Alpine participating in the research projects being orogeny shaped the Grimsel area around conducted at the Grimsel Test Site. The 40 million years ago when Alpine nappes Innertkirchen underground rock laboratory makes a sig- were thrust northwards over the rocks of nificant contribution to the long-term the Aar Massif, which sank to a depth of preservation and transfer of accumulated approx. twelve kilometres. The rocks Guttannen know-how to future generations. were then overprinted under high tem- perature and pressure conditions, result- Not a laboratory in the conventional ing in the formation of shear zones and sense fracture systems. Uplift (0.5 to 0.8 mm/a) 2 km Deep inside the mountain, geological and erosion processes, which are still Grimsel conditions range from fractured sections continuing today, brought the rocks of the Test Site Gletsch of rock to others that are intact. Water Aar Massif to the surface once more. The Grimsel- flow occurs in the former but not in the mineral fractures – for which the Grimsel pass latter. The Test Site thus provides ideal area is famous – formed around 16 mil- Oberwald boundary conditions for examining the lion years ago. Visit us! From June to October, Nagra offers groups the opportunity to experience free guided tours of the Grimsel Test Site. Join the thousands of people who have already visited us and witness first-hand how internationally renowned research is conducted in the laboratory. You can also combine a visit to the Test Site with a hike in the beautiful Grimsel region. More informa- tion on the Test Site is available at: fuehrungen.nagra.ch. Registration for a guided tour Renate Spitznagel: Phone +41 (0)56 437 12 82 [email protected] Grimsel Test Site Participating countries With a view to deep geological disposal Building blocks of a waste Taking responsibility Contribution of the rock laboratories management programme Our generation is producing radioactive Rock laboratories contribute significantly waste and it is our duty to dispose of this to answering questions concerning long- Laboratory studies waste in a responsible and sustainable term safety and also to verifying the tech- way. The waste producers have entrusted nical feasibility of constructing deep geo- Research projects in Nagra with developing and implementing logical repositories for radioactive waste. rock laboratories a waste management solution. The focus of research activities includes: System understanding • Geological and hydrogeological charac- The road to deep disposal terisation of rock formations that are Conceptual models Experts worldwide agree that deep geo- suitable for deep geological disposal Natural analogue logical disposal is a safe, long-term solu- • Properties and long-term behaviour of studies tion for radioactive waste. In Switzerland, the components of the engineered Site-specic eld it is required by law. Nagra outlines the safety barriers investigations steps to be taken on the road to deep • Migration behaviour and retention geological disposal in its Waste Man- properties of radioactive substances in a gement Programmes. the engineered safety barriers and in The Grimsel Test Site (Canton Bern) and the surrounding rock Safety Engineering the Mont Terri Rock Laboratory (Canton • Verification of the data and calculation analysis feasibility Jura) are important research centres models used in safety analyses both for the Swiss waste disposal pro- • Technologies for tunnel construction Deep geological repository gramme and for international collabora- and waste emplacement tion. Research in these laboratories fo- • International collaboration and ex- cuses on gaining and expanding expertise change of know-how Surface infrastructure concerning the safety of deep geological • Providing information to the public, repositories, the characterisation of rocks politicians and the authorities. Access structures and the functioning of the engineered Underground waste safety barriers. These research activities emplacement zone are complemented by external labora- tory studies and observations of similar processes found in nature (so-called nat- ural analogues). Safety barriers of a deep Reprocessing waste geological repository Several successive barriers confine the radioactive waste. Spent fuel assemblies The waste is shielded from impacts that could compromise safety and the radioactive substances are retained until they have decayed to natural levels. The engineered barriers of a deep geological repository for high-level waste consist of a low-solubility waste matrix (1a glass or 1b nuclear fuel) containing the radioactive 2 3 4 substances, a thick-walled 1a 1b steel canister (2; one-metre diameter) and a drift backfill of bentonite (3; mixture of clay minerals). The geological barrier is formed by the host rock (4) that surrounds the emplacement drifts. More than 30 years of research at the Grimsel Test Site Focus of research to date Present and future Current experiments Research activities have focused mainly Many deep repository projects will be at the Grimsel Test Site st CFM (Colloid Formation and on the following: refined and implemented in the 21 cen- Migration) Formation and • Developing techniques for site investi- tury. The research conducted at the migration of colloids and gations. One example is the remote Grimsel Test Site provides important their influence on radionu- clide mobility imaging of rocks using seismic groundwork for these developments. CIM (C-14/I-129 Migration tomography. When planning experiments, the main through aged cement) Testing the transport • Testing technologies for repository focus is on the feasibility and operational properties of C-14 and I-129 construction and evaluating their safety of the repositories. These experi- through cement barriers impact on the functioning of the ments aim to determine the behaviour of EBS Lab (Engineered Barrier System Laboratory) Experi- geological barrier. Examples include disposal systems over decades under re- ments with components of investigating the sealing of boreholes pository-relevant conditions, to optimise the engineered barriers and measurement of parameters or small changes to the rock caused technical procedures and to document FEBEX (Full-Scale Engi- by tunnel excavation. their safety. The following objectives have neered Barriers Experiment) 1:1-scale demonstration • Developing and testing the engineered been set for the coming years: experiment of the emplace- barrier system. These experiments • Performing experiments that demon- ment concept for high-level waste also provide important data for strate and verify the functioning of the GAST (Gas Permeable Seal predicting the long-term evolution of engineered and geological barrier Test) Gas sealing experiment: a deep geological repository. system of a deep geological repository. gas- permeable tunnel seals for the L/ILW repository • Verifying models and databases used To better quantify slowly occurring under realistic conditions and in safety analyses. This includes coupled processes, the conditions on a realistic scale HotBENT (High-Temperature experiments on the transport and prevailing in the repositories must be Bentonite Project) Investiga- retention of radioactive substances simulated over many years. tions of the safety function of bentonite barriers exposed to (radionuclides) in the rock or the • Development of new technologies for elevated temperatures effect of colloids and highly alkaline the emplacement of radioactive waste ISC (In-Situ Stimulation and solutions on the migration behaviour (e.g. remote handling and monitoring Circulation Test) Controlled hydraulic stimulation of of radionuclides. technologies). existing fault zones • Education and training of technical (Experiment of the Swiss Competence Center for experts and students. Energy Research – Supply of Electricity) LASMO (Large Scale Monitoring) Monitoring and characterisation of the geosphere LCS (Long-term Cement Studies) Cement injection FEBEX/ Tunnel system at the Grimsel Test Site experiment: long-term HotBENT • Approx. 1100 m of tunnels and caverns N interactions between cement • Approx. 6000 m of cored boreholes solutions, porewaters and BK • Year-round temperature approx. 13 °C cavern rock Central Yellow lines: boreholes (selection) LTD (Long-Term