Hostname: page-component-77c89778f8-rkxrd Total loading time: 0 Render date: 2024-07-23T03:39:34.707Z Has data issue: false hasContentIssue false

Cation Exchange and Mineral Reactions Observed in MX 80 Buffer Samples of the Prototype Repository In Situ Experiment in Äspö, Sweden

Published online by Cambridge University Press:  01 January 2024

Reiner Dohrmann*
Landesamt für Bergbau, Energie und Geologie (LBEG), Stilleweg 2, D-30655, Hannover, Germany
Stephan Kaufhold
Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, D-30655, Hannover, Germany
*E-mail address of corresponding author:


Bentonites are candidate materials for high-level radioactive waste (HLRW) repositories and, therefore, are investigated with respect to long-term stability. In order to identify possible bentonite alteration processes, long-term in situ tests are conducted in rock laboratories. The prototype repository in situ experiment (PR) is one of the best examples of this kind of test due to the size of the installation as well as the duration. In the present study, chemical and mineralogical alteration processes of the bentonite MX 80 after an 8 y heating period were investigated. The water content of all samples increased following inflowing Na-Ca-Cl-type granitic groundwater causing cation exchange in the bentonite buffer materials. Exchangeable magnesium was desorbed in the buffer and MgO concentration increased at the bentonite-Cu canister interface; the Mg sink could not be detected, however. CaO also accumulated at this interface mainly as Ca carbonate and Ca sulfate. Cu corrosion products were identified at the bentonite-canister interface by chemical analysis, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDX), and differential thermal analysis. Up to 0.5 mm into the bentonites Cu could be detected by SEM-EDX. No cristobalite dissolution was observed in contrast to other in situ tests in which iron heaters were used. The corrosion products and the lubricant which was added during manufacturing of the bentonite blocks were mixed with the bentonite at the bentonite-canister interface. A quantitative measure of that mixture was the decrease in the cation exchange capacity (CEC). The CEC also reduced in all other samples, however, compared to the CECs of the reference samples, particularly in the warmer deposition hole 5 compared to the colder deposition hole 6. Overall, the PR in situ experiment proved that cation exchange reactions occurred in full-scale bentonite buffer experiments in all bentonite blocks but structural degradation of smectite could not be identified.

Copyright © Clay Minerals Society 2014

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Aertens, M. Maes, N. Ravestyn, L. V. and Brassinnes, S., 2013 Overview of radionuclide migration experiments in the HADES Underground Research Facility at Mol (Belgium) Clay Minerals 48 153166.CrossRefGoogle Scholar
Alexander, W.R. Milodowski, A.E. Pitty, A.F. Hardie, S.M.L. Kemp, S.J. Rushton, J.C. Siathas, A. Siathas, A. MacKenzie, A.B. Korkeakoski, P. Norris, S. Sellin, P. and Rigas, M., 2013 Bentonite reactivity in alkaline solutions: interim results of the Cyprus Natural Analogue Project (CNAP) Clay Minerals 48 235249.CrossRefGoogle Scholar
Balko, B.A. Bosse, S.A. Cade, A.E. Jones-Landry, E.F. Amonette, J.E. and Daschbach, J.L., 2012 The effect of smectite on the corrosion of iron metal Clays and Clay Minerals 60 136152.CrossRefGoogle Scholar
Bauer, A. Schäfer, T. Dohrmann, R. Hofmann, H. and Kim, J.I., 2001 Smectite stability in slightly acid salt solutions and the fate of Eu, Th and U in solution Clay Minerals 36 93103.CrossRefGoogle Scholar
Bourdelle, F. Truche, L. Mosser-Ruck, R. Lorgeoux, C. Roszypal, C. and Michau, N., 2014 Iron-clay interactions under hydrothermal conditions: impact of iron specific surface area on reaction pathway revealed Chemical Geology 381 194205.CrossRefGoogle Scholar
Dohrmann, R. and Kaufhold, S., 2009 Three new, quick CEC methods for determining the amounts of exchangeable calcium cations in calcareous clays Clays and Clay Minerals 57 338352.CrossRefGoogle Scholar
Dohrmann, R. and Kaufhold, S., 2010 Determination of exchangeable calcium of calcareous and gypsiferous bentonites Clays and Clay Minerals 58 7988.CrossRefGoogle Scholar
Dohrmann, R. Genske, D. Karnland, O. Kaufhold, S. Kiviranta, L. Olsson, S. Plötze, M. Sandén, T. Sellin, P. Svensson, D. and Valter, M., 2012 Interlaboratory exchange of CEC and exchangeable cation results of bentonite buffer material. II. Alternative methods Clays and Clay Minerals 60 176185.CrossRefGoogle Scholar
Dohrmann, R. Kaufhold, S. and Lundqvist, B., 2013 The role of clays for safe storage of nuclear waste Handbook of Clay Science, Techniques and Applications 5B 677710.CrossRefGoogle Scholar
Dohrmann, R. Olsson, S. Kaufhold, S. and Sellin, P., 2013 Mineralogical investigations of the first package of the alternative buffer material test — II. Exchangeable cation population rearrangement Clay Minerals 48 215233.CrossRefGoogle Scholar
Fernández, A.M. and Villar, M.V., 2010 Geochemical behaviour of a bentonite barrier: results up to 8 years of thermo-hydraulic treatment in the laboratory Applied Geochemistry 25 809824.CrossRefGoogle Scholar
Friedrich, A. Grunewald, K. Klinnert, S. and Bechmann, W., 1996 Thermogravimetric and differential thermal analytical investigations on sewage farm soils Journal of Thermal Analysis and Calorimetry 46 15891597.CrossRefGoogle Scholar
García-Siñeriz, J.-L. Rey, M. and Mayor, J.-C., 2008 The engineered barrier experiment at Mont Terri Rock Laboratory Science and Technology Series n° 334 6575.Google Scholar
Huertas, F. Fariña, P. Farias, J. García-Siñeriz, J.L. Villar, M.V. Fernández, A.M. Martín, P.L. Elorza, F.J. Gens, A. Sánchez, M. Lloret, A. Samper, J. and Martínez, M.A., 2006 Full-scale Engineered Barriers experiment. Updated Final Report 1994–2004 Publicación Técnica ENRESA 05-0/2006 590 pp..Google Scholar
Jodin-Caumon, M.-C. Mosser-Ruck, R. Randi, A. Pierron, O. Cathelineau, M. and Michau, N., 2012 Mineralogical evolution of a claystone after reaction with iron under thermal gradient Clays and Clay Minerals 60 443455.CrossRefGoogle Scholar
Johannesson, L.-E. Börgesson, L. Goudarzi, R. Sandén, T. Gunnarsson, D. and Svemar, C., 2007 Prototype repository: A full-scale experiment at Äspö HRL Physics and Chemistry of the Earth 32 5876.CrossRefGoogle Scholar
Kaufhold, S. and Dohrmann, R., 2007 Implications from the LOT experiment regarding the selection of an optimum HLRW bentonite Clays in Natural & Engineered Barriers for Radioactive Waste Confinement 8586.Google Scholar
Kaufhold, S. Dohrmann, R., Karnland, O. Olsson, S. Dueck, A. Birgersson, M. Nilsson, U. Hernan-Håkansson, T. Pedersen, K. Nilsson, S. Eriksen, T.E. and Rosborg, B., 2009 Mineralogical and geochemical alteration of the MX80 bentonite from the LOT experiment Characterization of the A2 parcel Long-term Test of Buffer Material at the Äspö Hard Rock Laboratory 225250.Google Scholar
Kaufhold, S. and Dohrmann, R., 2009 Stability of bentonites in salt solutions I. Sodium chloride Applied Clay Science 45 171177.CrossRefGoogle Scholar
Kaufhold, S. and Dohrmann, R., 2010 Stability of bentonites in salt solutions II. Potassium chloride solution — Initial step of illitization? Applied Clay Science 49 98107.CrossRefGoogle Scholar
Kaufhold, S. Dohrmann, R. Sandén, T. Sellin, P. and Svensson, D., 2013 Mineralogical investigations of the first package of the alternative buffer material test — I. Alteration of bentonites Clay Minerals 48 199213.CrossRefGoogle Scholar
Keller, L.M. Seiphoori, A. Gasser, P. Lucas, F. Holzer, L. and Ferrari, A., 2014 The pore structure of compacted and partly saturated MX-80 bentonite at different dry densities Clays and Clay Minerals 62 174187.CrossRefGoogle Scholar
Landais, P. Kaufhold, S. and Dohrmann, R., 2013 Overview of the clay mineralogy studies presented at the ‘Clays in natural and engineered barriers for radioactive waste confinement’ meeting, Montpellier, October 2012 Clay Minerals 48 149152.CrossRefGoogle Scholar
Lloret, A. and Villar, M.V., 2007 Advances on the knowledge of the thermo-hydro-mechanical behaviour of heavily compacted “FEBEX” bentonite Physics and Chemistry of the Earth 32 701715.CrossRefGoogle Scholar
Li, X.-L. Bastiaens, W. van Marcke, P. Verstricht, J. Chen, G.J. Weetjens, E. and Sillen, X., 2010 Design and development of large-scale in situ PRACLAY heater test and horizontal high level radioactive waste disposal gallery seal test in Belgian HADES Journal of Rock Mechanics and Geotechnical Engineering 2 103110.CrossRefGoogle Scholar
Martín, P.L. Barcala, J.M. and Huertas, F., 2006 Large-scale and long-term coupled thermo-hydro-mechanic experiments with bentonite: the FEBEX mock-up test Journal of Iberian Geology 32 259282.Google Scholar
Muurinen, A., Karnland, O. Olsson, S. Dueck, A. Birgersson, M. Nilsson, U. Hernan-Håkansson, T. Pedersen, K. Nilsson, S. Eriksen, T.E. and Rosborg, B., 2009 Chemical Conditions in the A2 Parcel of the Long-Term Test of Buffer Material in Äspö (LOT) Long-term Test of Buffer Material at the Äspö Hard Rock Laboratory 167190.Google Scholar
Olsson, S. and Karnland, O., 2011 Mineralogical and chemical characteristics of the bentonite in the A2 test parcel of the LOT field experiments at Äspö HRL, Sweden Physics and Chemistry of the Earth 36 15451553.CrossRefGoogle Scholar
Osacký, M. Šucha, V. Miglierini, M. and Madejovaá, J., 2012 Reaction of bentonites with pyrite concentrate after wetting and drying cycles at 80°C: relevance to radioactive waste (Radwaste) storage Clay Minerals 47 465479.CrossRefGoogle Scholar
Perronnet, M. Villiéras, F. Jullien, M. Razafitianamaharavo, A. Raynal, J. and Bonnin, D., 2007 Towards a link between the energetic heterogeneities of the edge faces of smectites and their stability in the context of metallic corrosion Geochimica et Cosmochimica Acta 71 14631479.CrossRefGoogle Scholar
Pignatelli, I. Mugnaioli, E. Hybler, J. Mosser-Ruck, R. Cathelineau, M. and Michau, N., 2013 A multi-technique characterization of cronstedtite synthetized by iron-clay interaction in a step-by-step cooling procedure Clays and Clay Minerals 61 277289.CrossRefGoogle Scholar
Pignatelli, I. Bourdelle, F. Bartier, D. Mosser-Ruck, R. Truche, L. Mugnaioli, E. and Michau, N., 2014 Iron-clay interactions: a detailed study of claystone mineralogical transformation with emphasis on the formation of iron-rich T-O phyllosilicates in a step-by step cooling experiment from 90°C to 40°C Chemical Geology 387 111.CrossRefGoogle Scholar
Plötze, M. Kahr, G. Dohrmann, R. and Weber, H., 2007 Hydro-mechanical, geochemical and mineralogical characteristics of the bentonite buffer in a heater experiment. The HE-B project at the Mont Terri rock laboratory Physics and Chemistry of the Earth 32 730740.CrossRefGoogle Scholar
Romero, E. and Li, X.L., 2006 Thermo-hydro-mechanical characterization of OPHELIE backfill mixture Chinese Journal of Rock Mechanics and Engineering 25 733740.Google Scholar
Sellin, P. and Leupin, O.X., 2014 The use of clay as an engineered barrier in radioactive waste management Clays and Clay Minerals 61 477498.CrossRefGoogle Scholar
Svensson, D. Dueck, A. Nilsson, U. Olsson, S. Sandén, T. Lydmark, S. Jägerwall, S. Pedersen, K. and Hansen, S., 2011.Alternative Buffer Material — Status of the ongoing laboratory investigation of reference materials and test package 1Google Scholar
Svensson, P.D. and Hansen, S., 2013 Combined salt and temperature impact on montmorillonite hydration Clays and Clay Minerals 61 328341.CrossRefGoogle Scholar
Svensson, P.D. and Hansen, S., 2013 Redox chemistry in two iron-bentonite field experiments at Äspö Hard Rock Laboratory, Sweden: An XRD and Fe-K edge XANES study Clays and Clay Minerals 61 566579.CrossRefGoogle Scholar
Villar, M.V. and Lloret, A., 2007 Dismantling of the first section of the FEBEX in situ test: THM laboratory tests on the bentonite blocks retrieved Physics and Chemistry of the Earth 32 716729.CrossRefGoogle Scholar
Villar, M.V. Fernández, A.M. Rivas, P. Lloret, A. Daucausse, D. Montarges-Pelletier, E. Devineau, K. Villieras, F. Hynkovaá, E. Cechova, Z. Montenegro, L. Samper, J. Zheng, L. Robinet, J.C. Muurinen, A. Weber, H.P. Börgesson, L. and Sandén, T., 2006 FEBEX Post-Mortem Bentonite Analysis Publicación Técnica ENRESA, Spain 05-1/2006 183 pp..Google Scholar
Watson, C. Savage, D. Wilson, J. Benbow, S. Walker, C. and Norris, S., 2013 The Tournemire industrial analogue: reactive-transport modelling of a cement-clay interface Clay Minerals 48 167184.CrossRefGoogle Scholar