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Sample records for opalinus clay host

  1. Clay shale as host rock. A geomechanical contribution about Opalinus clay

    Lempp, Christof; Menezes, Flora; Sachwitz, Simon

    2016-01-01

    The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

  2. Clay shale as host rock. A geomechanical contribution about Opalinus clay; Tonstein als Wirtsgestein. Ein geomechanischer Beitrag ueber Opalinuston

    Lempp, Christof; Menezes, Flora; Sachwitz, Simon [Halle-Wittenberg Univ., Halle (Saale) (Germany). Inst. fuer Geowissenschaften und Geographie

    2016-12-15

    The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

  3. Investigations for the influence of geochemical parameters on the sorption and desorption of lanthanides and uranium onto opalinus clay as potential host rock for a repository

    Moeser, Christina

    2010-01-01

    The development of a disposal in deep geological formations for radioactive waste is a very important task for the future. The safety assessment for more than a hundred thousand years needs a full understanding of all processes of interaction between the radioactive waste and the surrounded formations. This work contributes to this understanding. The interaction between lanthanides (homologues of the actinides americium, curium and berkelium) / uranium and the host rock opalinus clay under influence of organic substances (NOM) have been analyzed and discussed. The complex system was split into 3 binary basic systems with the following interactions - Interactions between lanthanides / uranium and NOM - Interactions between lanthanides / uranium and the opalinus clay - Interactions between NOM and opalinus clay All binary systems can be influenced by geological parameters like pH, ion strength and competing cations. The sorption / desorption of the lanthanides onto the opalinus clay is analyzed via inductively coupled plasma mass spectrometry. For the investigation of the complexation behavior of metals with NOM we used capillary electrophoresis coupled with inductively coupled plasma mass spectrometry. Under these conditions the chosen model organic humic acid affected the sorption of the lanthanides onto opalinus clay favorably. The smaller organic compounds, which dominate in the composition of the clay organics, remobilized the metals after sorption onto clay and the sorption can be inhibited by NOM. Due to the reduced metal sorption onto Opalinus clay by NOM, a migration through the clay may be possible.

  4. Characterisation of gas transport properties of the Opalinus clay, a potential host rock formation for radioactive waste disposal

    Marschall, P.; Horseman, S.; Gimmi, T.

    2005-01-01

    The Opalinus Clay in Northern Switzerland has been identified as a potential host rock formation for the disposal of radioactive waste. Comprehensive understanding of gas transport processes through this low-permeability formation forms a key issue in the assessment of repository performance. Field investigations and laboratory experiments suggest an intrinsic permeability of the Opalinus Clay in the order of 10 -20 to 10 -21 m 2 and a moderate anisotropy ratio ≤ 10. Porosity depends on clay content and burial depth; values of ∼ 0.12 are reported for the region of interest. Porosimetry indicates that about 10-30% of voids can be classed as macro-pores, corresponding to an equivalent pore radius > 25 nm. The determined entry pressures are in the range of 0.4-10 MPa and exhibit a marked dependence on intrinsic permeability. Both in situ gas tests and gas permeameter tests on drill-cores demonstrate that gas transport through the rock is accompanied by pore water displacement, suggesting that classical flow concepts of immiscible displacement in porous media can be applied when the gas entry pressure (i.e. capillary threshold pressure) is less than the minimum principal stress acting within the rock. Essentially, the pore space accessible to gas flow is restricted to the network of connected macro-pores, which implies a very low degree of desaturation of the rock during the gas imbibition process. At elevated gas pressures (i.e. when gas pressure approaches the level of total stress that acts on the rock body), evidence was seen for dilatancy controlled gas transport mechanisms. Further field experiments were aimed at creating extended tensile fractures with high fracture transmissivity (hydro- or gas-fractures). The test results lead to the conclusion that gas fracturing can be largely ruled out as a risk for post-closure repository performance. (authors)

  5. Far Field Sorption Data Bases for Performance Assessment of a High-Level Radioactive Waste Repository in an Undisturbed Opalinus Clay Host Rock

    Bradburry, M.; Baeyens, B.

    2003-08-01

    An Opalinus Clay formation in the Zuercher Weinland is under consideration by Nagra as a potential location for a high-level and long-Iived intermediate-level radioactive waste repository. Performance assessment studies will be performed for this site and the purpose of this report is to describe the procedures used to develop sorption data bases appropriate for an undisturbed Opalinus Clay host rock which are required for such safety analysis calculations. In tight, low water content argillaceous rock formations such as Opalinus Clay, there is uncertainty concerning the in situ pH/P CO 2 . In order to take this intrinsic uncertainty into account porewater chemistries were calculated for a reference case, pH = 7.24, and for two other pH values, 6.3 and 7.8. Sorption data bases are given for the three cases. The basis for the sorption data bases is 'in-house' sorption measurements for Cs(I), Sr(II), Ni(II), Eu(III), Sn(IV), Se(IV), Th(IV) and I(-I) carried out on Opalinus Clay samples from Mont Terri (Canton Jura) since at the time the experiments were performed no core samples from the Benken borehole (Zuercher Weinland) were available. The Opalinus Clay at Mont Terri and Benken are part of the same geological formation . Despite having directly measured data for the above key radionuclides, some of the required distribution ratios (Rd) used to generate the sorption data bases still came from the open literature. An important part of this report is concerned with describing the procedures whereby these selected literature Rd values were modified so as to apply to the Benken Opalinus Clay mineralogy and groundwater chemistries calculated at the three pH values given above. The resulting Rd values were then further modified using so-called Lab→Field transfer factors to produce sorption values which were appropriate to the in situ bulk rock for the selected range of water chemistry conditions. Finally, it is important to have some appreciation of the uncertainties

  6. Far Field Sorption Data Bases for Performance Assessment of a High-Level Radioactive Waste Repository in an Undisturbed Opalinus Clay Host Rock

    Bradburry, M.; Baeyens, B

    2003-08-01

    An Opalinus Clay formation in the Zuercher Weinland is under consideration by Nagra as a potential location for a high-level and long-Iived intermediate-level radioactive waste repository. Performance assessment studies will be performed for this site and the purpose of this report is to describe the procedures used to develop sorption data bases appropriate for an undisturbed Opalinus Clay host rock which are required for such safety analysis calculations. In tight, low water content argillaceous rock formations such as Opalinus Clay, there is uncertainty concerning the in situ pH/P{sub CO{sub 2}}. In order to take this intrinsic uncertainty into account porewater chemistries were calculated for a reference case, pH = 7.24, and for two other pH values, 6.3 and 7.8. Sorption data bases are given for the three cases. The basis for the sorption data bases is 'in-house' sorption measurements for Cs(I), Sr(II), Ni(II), Eu(III), Sn(IV), Se(IV), Th(IV) and I(-I) carried out on Opalinus Clay samples from Mont Terri (Canton Jura) since at the time the experiments were performed no core samples from the Benken borehole (Zuercher Weinland) were available. The Opalinus Clay at Mont Terri and Benken are part of the same geological formation . Despite having directly measured data for the above key radionuclides, some of the required distribution ratios (Rd) used to generate the sorption data bases still came from the open literature. An important part of this report is concerned with describing the procedures whereby these selected literature Rd values were modified so as to apply to the Benken Opalinus Clay mineralogy and groundwater chemistries calculated at the three pH values given above. The resulting Rd values were then further modified using so-called Lab{yields}Field transfer factors to produce sorption values which were appropriate to the in situ bulk rock for the selected range of water chemistry conditions. Finally, it is important to have some

  7. Concrete-Opalinus clay interaction

    Jenni, A.; Maeder, U.; Lerouge, C.; Gaboreau, S.; Schwyn, B.

    2012-01-01

    Document available in extended abstract form only. Designs for deep geologic disposal of radioactive waste foresee cementitious materials as structural elements, backfill or waste matrix. Therefore, studies of interactions between cement and all other materials involved are important. Interactions are mostly driven by chemical gradients in pore water and might lead to mineralogical alterations in the barrier system, which in turn influence properties like swelling pressure, permeability, or specific retention in case of clay materials. Existing laboratory and in-situ studies using clay-stone revealed significant alteration in both cement and clay-stone. Phase dissolution, precipitation, and carbonation, were found to cause an overall porosity increase in the cement with a possible decrease close to the interface, and clogging in the clay-stone [2]. Most of the work was done on cement pastes rather than concretes to avoid analytical complications caused by aggregates, and the scale of investigation was chosen in the range of centimetres rather than micrometers. The Cement-Clay Interaction (CI) experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) aims at replicating some of the processes at interfaces to be expected.For this purpose, two vertical cylindrical boreholes (384 mm diameter, up to 10 m length) in Opalinus Clay (OPA) were filled with layers of three different concretes and bentonite. The concrete formulations are based on common aggregate content and grain size distributions, combined with three different cements: Portland cement (OPC), ESDRED cement especially designed for repository applications (40% of cement substituted with silica fume), and low alkali cement (LAC, containing slag and nano-silica).In this study, we present a characterisation of the three concrete-OPA interfaces after two years of alteration and deduce possible mechanisms. Backscattered electron (BE) imaging and energy dispersive spectrum (EDX) element mapping

  8. Strengthening and stress relaxation of Opalinus Clay

    Schulze, Otto

    2010-01-01

    Document available in extended abstract form only. Full text follows: In the framework of the EU-project NF-PRO (e.g. RTDC-5, Synthesis Report, D-No 5.2.3), special emphasis was put on the investigation and modelling of near-field processes in a candidate host rock: http://project.nf-pro.org/workspaces/rtdc5/deliverables/d5_2_3_rtdc_5_synthesis_report_final_version. The coupled TMHC-processes under consideration mainly concern the interaction between the host rock in and near to the EDZ and the waste products in its immediate vicinity. With respect to long-term safety analyses, there is no doubt that a sound process understanding is required. However, safe disposal also requires a suitable multi-barrier-system. This has to consist of technical and geo-technical barriers (e.g. container and backfill) but also of a strong geological barrier. Comparing the self-sealing capacity of the candidate host rocks, i.e. salt, clay and crystalline rock formations, where underground rooms will be inevitably backfilled only in part for technical reasons, in a salt formation convergence by viscous deformation provokes the re-establishing of a tight system, whereas in a crystalline rock formation long-term isolation has to be guaranteed solely by the technical and geotechnical components. This work is concentrated on the question, whether convergence and reduction of open space by long-term creep will take place also in a clay-stone formation, where laboratory investigation on Opalinus Clay from the Mont Terri Rock Laboratory was performed for this purpose. Several results from the work on the long-term deformation behaviour of clay-stone exist already. Nevertheless, to the author's knowledge the sound proof of a time-dependent and non-dilatant viscous deformation in the undisturbed far-field of clay-stone is still missing. Results from the rock laboratory at the Mt. Terri site yield hints for an anisotropic state of in-situ stresses, which may continue to exist in the

  9. Water Retention Curves of Opalinus Clay

    Villar, M. V.; Romero, F. J.

    2012-11-01

    The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

  10. Water Retention Curves of Opalinus Clay

    Villar, M. V.; Romero, F. J.

    2012-01-01

    The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

  11. Assessment of geomechanical properties of intact Opalinus Clay - Expert report

    Amann, F.; Vogelhuber, M.

    2015-11-01

    This comprehensive report published by the Swiss Federal Nuclear Safety Inspectorate ENSI presents an expert report published on the assessment of the geomechanical properties of intact Opalinus Clay. This review report addresses the conceptual constitutive framework for repositories in Opalinus Clay. The author addresses the geomechanical fundamentals that are necessary in order to adequately judge experiments on intact Opalinus Clay and the interpretation of the results. The report assesses in detail the various test series on intact Opalinus Clay carried out along with the interpretations made by experts and NAGRA. Further assessments are quoted including those on sample geometries tested, effective strength properties, undrained shear strength properties and elastic properties. The results of work done by other experts are also presented and discussed. The report is completed with a list of relevant literature

  12. Assessment of geomechanical properties of intact Opalinus Clay - Expert report

    Amann, F. [Eidgenössische Technische Hochschule ETHZ, Zürich (Switzerland); Vogelhuber, M. [Dr. von Moos AG, Geotechnisches Büro, Zürich (Switzerland)

    2015-11-15

    This comprehensive report published by the Swiss Federal Nuclear Safety Inspectorate ENSI presents an expert report published on the assessment of the geomechanical properties of intact Opalinus Clay. This review report addresses the conceptual constitutive framework for repositories in Opalinus Clay. The author addresses the geomechanical fundamentals that are necessary in order to adequately judge experiments on intact Opalinus Clay and the interpretation of the results. The report assesses in detail the various test series on intact Opalinus Clay carried out along with the interpretations made by experts and NAGRA. Further assessments are quoted including those on sample geometries tested, effective strength properties, undrained shear strength properties and elastic properties. The results of work done by other experts are also presented and discussed. The report is completed with a list of relevant literature.

  13. Mineralogical and Micro-fabric investigation of the Sandy Facies of Opalinus Clay (Mont Terri)

    Kaufhold, Annette; Siegesmund, Siegfried; Dohrmann, Reiner; Graesle, Werner; Plischke, Ingo

    2013-01-01

    In the field of geological disposal of radioactive waste in many countries argillaceous formations are considered as potential host rock. For the understanding of the long-term behaviour of clay host rock, it is important to understand the interaction between mechanical behaviour, micro-fabric, and mineral composition. Previous publications showed that particularly the carbonate content and the arrangement of the carbonate grains (as cement in the matrix or as shells) determines the mechanical strength of Opalinus Clay and Callovo-Oxfordian Clay specimens, respectively. Klinkenberg et al. (2009) studied the shaly facies of Opalinus Clay, however, the actual deposit is planned to be built in the sandy facies of Opalinus Clay. The aim of the present study is to investigate the relation between micro-fabric, mineral composition, and mechanical properties of different samples derived from the sandy facies (BLT-A2). Image analysis showed that the carbonates in the sandy facies mainly occur as 1) matrix which in turn acts as cement. Carbonates also occur 2) in the fine sand fraction and 3) biogenic carbonates as traces. The carbonates of the sandy facies, therefore, appear to be similar to the carbonates of the Callovo-Oxfordian Clay with respect to their possible influence on failure strength. The mechanical testing showed that the shear strength increases with increasing carbonate content. This phenomenon was also observed for the samples of the Callovo-Oxfordian Clay, while the opposite relation was found for the shaly facies of the Opalinus Clay. Preliminary results presented here, indicate that the sandy facies (drilling BLT-A2) and Callovo-Oxfordian Clay show similar mechanical properties - in detail: 1) Micro-fabric: carbonates predominate in the matrix, 2) Mineralogy: high carbonate content and 3) Mechanical testing: shear strength increases with increasing carbonate content, where the type of carbonates which controls the increase of strength has to be

  14. Anisotropic Behaviour of Opalinus Clay Through Consolidated and Drained Triaxial Testing in Saturated Conditions

    Favero, Valentina; Ferrari, Alessio; Laloui, Lyesse

    2018-05-01

    This paper investigates the anisotropic hydro-mechanical behaviour of Opalinus Clay shale, the host material currently being considered for the construction of a nuclear waste repository in Switzerland. Consolidated and drained triaxial tests on Opalinus Clay from the Mont Terri URL have been conducted in order to derive information on its strength and stiffness properties. Opalinus Clay specimens were tested both parallel to bedding (P-specimens) and perpendicular to bedding (S-specimens). The considered effective confining stress range (from 2 to 12 MPa) has been selected in order to reproduce possible in situ stress conditions for the repository. In this work, particular attention has been paid to the experimental procedure in order to ensure consolidated conditions and avoid generation of unwanted excess pore water pressure during drained shearing. The Skempton B parameter has been determined for all the tested specimens in order to ensure saturation. Both single-stage and multistage triaxial testing procedures were adopted in the experimental campaign. The results of the triaxial tests highlight an anisotropic elastic response of Opalinus Clay: S-specimens present a more compliant behaviour than P-specimens. The values of the Young modulus are found to increase with the increase in mean effective stress. The analysis of the peak and ultimate shear strength results reveals that the material behaves in a similar manner regardless of the considered direction of loading (P and S directions) with respect to the bedding orientation. Peak and ultimate failure envelopes for Opalinus Clay were derived for the investigated stress range.

  15. Near Field sorption Data Bases for Compacted MX-80 Bentonite for Performance Assessment of a High-Level Radioactive Waste Repository in Opalinus Clay Host Rock

    Bradbury, M.; Baeyens, B

    2003-08-01

    Bentonites of various types and compacted forms are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Nagra is currently considering an Opalinus clay (OPA) formation in the Zuercher Weinland as a potential location for a high-level radioactive waste repository. A compacted MX-80 bentonite is foreseen as a potential backfill material. Performance assessment studies will be performed for this site and one of the requirements for such an assessment are sorption data bases (SDB) for the bentonite near-field. The purpose of this report is to describe the procedures used to develop the SDB. One of the pre-requisites for developing a SDB is a water chemistry for the compacted bentonite porewater. For a number of reasons mentioned in the report, and discussed in more detail elsewhere, this is not a straightforward task. There are considerable uncertainties associated with the major ion concentrations and in particular with the system pH and Eh. The MX-80 SDB was developed for a reference bentonite porewater (pH = 7.25) which was calculated using the reference OPA porewater. In addition, two further SDBs are presented for porewaters calculated at pH values of 6.9 and 7.9 corresponding to lower and upper bound values calculated for the range of groundwater compositions anticipated for the OPA host rock. 'In house' sorption isotherm data were measured for Cs(I), Ni(II), Eu(III), Th(IV), Se(IV) and 1(-1) on the 'as received' MX-80 material equilibrated with a simulated porewater composition. Complementary 'in house' sorption edge and isotherm measurements on conditioned Na/Ca montmorillonites were also available for many of these radionuclides. These data formed the core of the SDB. Nevertheless, some of the required sorption data still had to be obtained from the open literature. An important part of this report is concerned with describing selection procedures and the modifications

  16. Influence of carbonate micro-fabrics on the failure strength of Callovo-Oxfordian clay stones and Opalinus Clay

    Klinkenberg, M.; Dohrmann, R.; Kaufhold, S.; Siegesmund, S.

    2010-01-01

    Document available in extended abstract form only. The potential use of clay stones as host rock for radioactive waste disposal is currently investigated. For this application, hydraulic conductivity, swelling properties, water uptake, rheological and mechanical properties are of great importance. The Opalinus Clay (Mont-Terri, Switzerland) and the Callovo- Oxfordian clay stone (France) are the most frequently studied clay stones. One goal is to develop a numerical model being able to predict the mechanical behaviour of clay stones under repository-like conditions. Experimental investigations reveal that Opalinus Clay and Callovo-Oxfordian clay stone behave different with respect to the dependence of mechanical strength on the carbonate content. The failure strength of Opalinus Clay decreases with increasing carbonate content, whereas it increases with increasing carbonate content when Callovo-Oxfordian clay stone is considered. To supply proper data and enable reliable model assumptions, the use of suitable experimental techniques for the description of the microstructure is indispensable. After mechanical testing, samples were taken perpendicular to the bedding and polished sections were prepared. The micro-fabrics were investigated using scanning electron microscopy (SEM) and image analysis. Backscattered electron (BSE) images were used for the image analysis because carbonates can be extracted by grey level analysis. The image analysis of the extracted particles provides the following parameters: area, longest and shortest axis of an ellipse (surrounding the particle), perimeter, the angle to horizontal (longest axis), and the aspect ratio (longest axis/shortest axis). Callovo-Oxfordian clay stone shows a homogenous distribution of fine-grained carbonates and dovetail connection of calcium carbonate with the clayey matrix. In contrast Opalinus Clay shows large elongated carbonate grains (high aspect ratios) of shell fragments. Cracks are mostly related to these

  17. Speciation of neptunium after diffusion in Opalinus Clay

    Reich, Tobias; Amayri, Samer; Drebert, Jakob; Froehlich, Daniel R.; Grolimund, Daniel; Rosemann, Jonathan [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Kaplan, Ugras [Paul Scherrer Institut, Villigen (Switzerland). Swiss Light Source

    2015-07-01

    Argillaceous rock formations are under consideration as a potential host rock for the construction of high-level nuclear waste repositories. Under environmental conditions the most stable oxidation states of {sup 237}Np (t{sub 1/2}=2.1 x 10{sup 6} a) are Np(IV) and Np(V). We have investigated the sorption and diffusion of the more mobile Np(V) in Opalinus Clay (OPA, Mont Terri, Switzerland) (Wu et al. 2009, Froehlich et al. 2011 and 2012 a). OPA, which is present in Switzerland and southern Germany, possesses a micro-scale heterogeneity and is composed of several types of clay minerals, but also of calcite, quartz and iron(II)-bearing minerals. In our previous diffusion (Wu et al. 2009) and anaerobic sorption experiments (Froehlich et al. 2011), we observed higher distribution coefficients, K{sub d}, than expected from batch experiments performed in air, indicating that a partial reduction of Np(V) to Np(IV) had occurred. To test this hypothesis, different sorption and diffusion samples with Np(V) were prepared at pH 7.6 for spatially resolved molecular-level investigations at the microXAS beamline at the Swiss Light Source (PSI, Villigen, Switzerland) (Froehlich et al. 2012 b). Elemental distributions of Ca, Fe and Np have been determined by μ-XRF mapping. Regions of high Np concentration were subsequently investigated by Np L{sub III}-edge μ-XANES. In most samples Np spots with considerable amounts of tetravalent Np could be found, even when the experiments were performed under ambient-air conditions. In some cases, almost pure Np(IV) L{sub III}-edge XANES spectra were recorded. In case of the anaerobic sorption sample, a clear correlation between Np and Fe was observed by μ-XRF, indicating that iron(II)-bearing minerals could be responsible for the reduction of Np(V). μ-XRD measurements of this sample showed that pyrite is at least one of the redox-active phases determining the speciation of Np in OPA. In this case, Np was accumulated on pyrite, indicating

  18. Characterisation of gas transport properties of the Opalinus clay, a potential host rock formation for radioactive waste disposal; Caracterisation des proprietes des argiles d'Opalinus (roche d'accueil potentielle pour un stockage de dechets radioactifs) relatives au transport des gaz

    Marschall, P. [Nagra - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Horseman, S. [British Geological Survey, Kingsley Dunham Centre, Keyworth (United Kingdom); Gimmi, T. [Bern Univ. (Switzerland); Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    2005-07-01

    The Opalinus Clay in Northern Switzerland has been identified as a potential host rock formation for the disposal of radioactive waste. Comprehensive understanding of gas transport processes through this low-permeability formation forms a key issue in the assessment of repository performance. Field investigations and laboratory experiments suggest an intrinsic permeability of the Opalinus Clay in the order of 10{sup -20} to 10{sup -21} m{sup 2} and a moderate anisotropy ratio {<=} 10. Porosity depends on clay content and burial depth; values of {approx} 0.12 are reported for the region of interest. Porosimetry indicates that about 10-30% of voids can be classed as macro-pores, corresponding to an equivalent pore radius > 25 nm. The determined entry pressures are in the range of 0.4-10 MPa and exhibit a marked dependence on intrinsic permeability. Both in situ gas tests and gas permeameter tests on drill-cores demonstrate that gas transport through the rock is accompanied by pore water displacement, suggesting that classical flow concepts of immiscible displacement in porous media can be applied when the gas entry pressure (i.e. capillary threshold pressure) is less than the minimum principal stress acting within the rock. Essentially, the pore space accessible to gas flow is restricted to the network of connected macro-pores, which implies a very low degree of desaturation of the rock during the gas imbibition process. At elevated gas pressures (i.e. when gas pressure approaches the level of total stress that acts on the rock body), evidence was seen for dilatancy controlled gas transport mechanisms. Further field experiments were aimed at creating extended tensile fractures with high fracture transmissivity (hydro- or gas-fractures). The test results lead to the conclusion that gas fracturing can be largely ruled out as a risk for post-closure repository performance. (authors)

  19. Anisotropic modelling of Opalinus Clay behaviour: From triaxial tests to gallery excavation application

    François Bertrand

    2017-06-01

    Full Text Available Deep repository in geological formations is the preferential solution considered in many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in situ and laboratory tests are conducted on Opalinus Clay to demonstrate the feasibility of deep disposal in this argillaceous formation. This paper presents a constitutive model able to fit the experimental data obtained from some triaxial tests conducted by Jahns (2013 on cores from borehole Schlattingen SLA-1. The elasto-plastic behaviour of Opalinus Clay is reproduced thanks to a Drucker-Prager model, taking into account the anisotropy behaviour of this sedimentary rock. The objective is to employ a single set of parameters representative of the material. In a second version of the model, the stress-dependence of the elastic properties and damage are taken into account. Finally, the parameters calibrated with experimental tests are used to simulate the excavation of a gallery with a second gradient approach.

  20. Frictional Properties of Opalinus Clay: Implications for Nuclear Waste Storage

    Orellana, L. F.; Scuderi, M. M.; Collettini, C.; Violay, M.

    2018-01-01

    The kaolinite-bearing Opalinus Clay (OPA) is the host rock proposed in Switzerland for disposal of radioactive waste. However, the presence of tectonic faults intersecting the OPA formation put the long-term safety performance of the underground repository into question due to the possibility of earthquakes triggered by fault instability. In this paper, we study the frictional properties of the OPA shale. To do that, we have carried out biaxial direct shear experiments under conditions typical of nuclear waste storage. We have performed velocity steps (1-300 μm/s) and slide-hold-slide tests (1-3,000 s) on simulated fault gouge at different normal stresses (4-30 MPa). To establish the deformation mechanisms, we have analyzed the microstructures of the sheared samples through scanning electron microscopy. Our results show that peak (μpeak) and steady state friction (μss) range from 0.21 to 0.52 and 0.14 to 0.39, respectively, thus suggesting that OPA fault gouges are weak. The velocity dependence of friction indicates a velocity strengthening regime, with the friction rate parameter (a - b) that decreases with normal stress. Finally, the zero healing values imply a lack of restrengthening during interseismic periods. Taken together, if OPA fault reactivates, our experimental evidence favors an aseismic slip behavior, making the nucleation of earthquakes difficult, and long-term weakness, resulting in stable fault creeping over geological times. Based on the results, our study confirms the seismic safety of the OPA formation for a nuclear waste repository.

  1. Speciation of plutonium during sorption and diffusion in Opalinus clay

    Kaplan, Ugras

    2013-01-01

    The presented work was carried out in the framework of the BMWi-project ''Interaction and migration of actinides in natural clay rocks taking into account humic substances and clay organic matter - Interactions of neptunium and plutonium with natural clay rocks''. For the long-term safety assessments of nuclear repositories, the possible migration of the radiotoxic wastes into the environment must be considered. Due to its long half-life (T 1/2 = 24000 y) 239 Pu has a significant contribution to the radiotoxicity of spent nuclear fuel in a repository after long periods of storage. The redox-sensitive plutonium has a very complicated chemical behavior. In aqueous solution under environmental relevant conditions Pu can exist in oxidation states +III to +VI and it can exist in up to four oxidation states simultaneously in a solution. Clays are considered as a possible host rock formation for of high-level radioactive waste disposal. Therefore, detailed information on the mobilization and immobilization of plutonium through / into the groundwater from a repository are of special interest. In this work new insights into the interaction between Pu and natural Opalinus clay (OPA, Mont Terri, Switzerland) are obtained with regard to the disposal of heat-generating radioactive waste in a deep geological repository.rnThe focus of this work was on the determination of the speciation of Pu on the mineral surface after sorption and diffusion process by different synchrotron based techniques (μ-XRF, μ-XANES/-EXAFS, μ-XRD, and EXAFS/XANES). The interaction between Pu and OPA was studied in batch sorption and diffusion experiments in dependence of various experimental parameters (e.g. pH, Pu oxidation state). Sorption experiments showed that some experimental parameters (e.g. temperature, humic acid) have a significant impact on the sorption of Pu on OPA. Speciation studies were performed as a function of various chemical parameters on powder samples form batch experiments as

  2. Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

    Soler, J.M.

    1999-09-01

    Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

  3. Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

    Soler, J.M.

    1999-09-01

    Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

  4. The shale gas potential of the Opalinus Clay and Posidonia Shale in Switzerland - A first assessment

    Leu, W. [Geoform Ltd, Villeneuve (Switzerland); Gautschi, A. [NAGRA, Wettingen (Switzerland)

    2014-07-01

    There has been recent interest in the shale gas potential of the Opalinus Clay and Posidonia Shale (Middle and Lower Jurassic) below the Swiss Molasse Basin in the light of the future role of domestic gas production within the expected future energy shift of Switzerland and possible conflicts in underground use. The Opalinus Clay of northern Switzerland is a potential host rock for repositories of both high-level and low-to-intermediate level radioactive waste and the exploitation of shale gas resources within or below this formation would represent a serious conflict of use. Well data from northern Switzerland shows that these two formations are unsuitable for future shale gas recovery. They never reached the gas window during their burial history (maturity values are ≤ 0.6% R{sub o}) and as a consequence never generated significant quantities of thermogenic gas. Geochemical data further shows that the average TOC values are in the range of 0.7%, i.e. clearly below accepted values of more than 1.5% for prospective shales. A review of available exploration data for the Opalinus Clay and Posidonia Shale in the deeper and western part of the Swiss Molasse Basin indicate that their shale gas potential may be substantial. The gross Posidonia Shale thickness increases from central Switzerland from less than 10 m to over 100 m in the Yverdon-Geneva area and is characterised by numerous bituminous intervals. A simplified shale gas resource calculation results for a geologically likely scenario in a technically recoverable gas volume of ∼120 billions m{sup 3}. The current database for such estimates is small and as a consequence, the uncertainties are large. However, these first encouraging results support a more detailed exploration phase with specific geochemical and petrophysical analysis of existing rock and well log data. (authors)

  5. The shale gas potential of the Opalinus Clay and Posidonia Shale in Switzerland - A first assessment

    Leu, W.; Gautschi, A.

    2014-01-01

    There has been recent interest in the shale gas potential of the Opalinus Clay and Posidonia Shale (Middle and Lower Jurassic) below the Swiss Molasse Basin in the light of the future role of domestic gas production within the expected future energy shift of Switzerland and possible conflicts in underground use. The Opalinus Clay of northern Switzerland is a potential host rock for repositories of both high-level and low-to-intermediate level radioactive waste and the exploitation of shale gas resources within or below this formation would represent a serious conflict of use. Well data from northern Switzerland shows that these two formations are unsuitable for future shale gas recovery. They never reached the gas window during their burial history (maturity values are ≤ 0.6% R o ) and as a consequence never generated significant quantities of thermogenic gas. Geochemical data further shows that the average TOC values are in the range of 0.7%, i.e. clearly below accepted values of more than 1.5% for prospective shales. A review of available exploration data for the Opalinus Clay and Posidonia Shale in the deeper and western part of the Swiss Molasse Basin indicate that their shale gas potential may be substantial. The gross Posidonia Shale thickness increases from central Switzerland from less than 10 m to over 100 m in the Yverdon-Geneva area and is characterised by numerous bituminous intervals. A simplified shale gas resource calculation results for a geologically likely scenario in a technically recoverable gas volume of ∼120 billions m 3 . The current database for such estimates is small and as a consequence, the uncertainties are large. However, these first encouraging results support a more detailed exploration phase with specific geochemical and petrophysical analysis of existing rock and well log data. (authors)

  6. Project Opalinus Clay: Sorption Data Bases For Opalinus Clay Influenced By A High pH Plume

    Bradbury, M.H.; Baeyens, B

    2004-11-01

    The interaction of groundwater with the large quantities of cement/concrete used in the construction and backfilling of emplacement tunnels containing long-lived intermediate level radioactive waste may give rise to the release of a pulse of hyper alkaline fluid (pH plume) into the surrounding rock. Since the pH of this plume could remain in excess of 12.5 for tens of thousands of years, many minerals in a sedimentary host rock would be unstable leading to dissolution reactions, secondary mineral precipitation and changes in groundwater chemistry. An Opalinus day formation in the Zuercher Weinland, is under consideration by Nagra as a potential host rock for a repository of spent fuel (SF), vitrified high-level waste (HLW) from reprocessing of spent fuel and long-lived intermediate-Ievel radioactive waste (ILW). The purpose of this report is to assess the effects of the interactions between a pH plume and Opalinus day on the sorption properties of the formation and to provide appropriate sorption data bases. (author)

  7. Hydro-mechanical aspects: glacial loading/erosion - the opalinus clay study

    Marschall, P.; Kupfer, T.; Kuhlmann, U.

    2004-01-01

    In Nagra's high level waste programme the future geological evolution of the investigation area in the Zurcher Weinland (NE Switzerland) is considered over a time period of around 1 Ma. Uplift, erosion and climatic changes were identified as processes that may affect the long-term performance of a repository for spent fuel (SF), vitrified high-level waste (HLW) and long-lived intermediate-level waste (ILW). The possible impact of those long-term processes on the barrier function of the host rock formation (Opalinus Clay) comprises: (i) the change of the vertical hydraulic gradient caused by changing recharge/discharge conditions in the regional aquifer systems; (ii) permeability enhancement of the host rock formation due to the uplift process; and (iii) expulsion of contaminated pore water from the disposal area as a result of repeated glacial loading. Due to the fact that the discharge level of the regional aquifer systems is defined by the Rhine valley and the regional recharge areas are characterised by moderate elevations (typically 2 are not expected within the next several million years. Hence, the topography of NE Switzerland together with the favourable hydraulic properties of the host rock formation prevent efficiently the vertical exchange of groundwater between the regional aquifer systems. Even on geological time scales of millions of years the expected vertical pore water flow through the host rock formation is in the order of 10 -14 m/s and lower. At present, the Opalinus Clay forms a perfect hydraulic barrier. The process of ongoing uplift, however, may give rise to embrittlement of the rock, entailed by permeability enhancement. Evidence for permeability enhancement of Opalinus Clay in shallow depth was observed by Hekel (1994). On the other hand, regional studies confirmed the low permeability of the Opalinus Clay formation in greater depth even when fractured (Gautschi, 2001; Marschall et al., 2003). Such evidence, together with conceptual

  8. Fifteen years of microbiological investigation in Opalinus Clay at the Mont Terri rock laboratory (Switzerland)

    Leupin, O.X. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); Bernier-Latmani, R.; Bagnoud, A. [Swiss Federal Office of Technology EPFL, Lausanne (Switzerland); Moors, H.; Leys, N.; Wouters, K. [Belgian Nuclear Research Centre SCK-CEN, Mol (Belgium); Stroes-Gascoyne, S. [University of Saskatchewan, Saskatoon (Canada)

    2017-04-15

    Microbiological studies related to the geological disposal of radioactive waste have been conducted at the Mont Terri rock laboratory in Opalinus Clay, a potential host rock for a deep geologic repository, since 2002. The metabolic potential of microorganisms and their response to excavation-induced effects have been investigated in undisturbed and disturbed claystone cores and in pore- (borehole) water. Results from nearly 15 years of research at the Mont Terri rock laboratory have shown that microorganisms can potentially affect the environment of a repository by influencing redox conditions, metal corrosion and gas production and consumption under favourable conditions. However, the activity of microorganisms in undisturbed Opalinus Clay is limited by the very low porosity, the low water activity, and the largely recalcitrant nature of organic matter in the claystone formation. The presence of microorganisms in numerous experiments at the Mont Terri rock laboratory has suggested that excavation activities and perturbation of the host rock combined with additional contamination during the installation of experiments in boreholes create favourable conditions for microbial activity by providing increased space, water and substrates. Thus effects resulting from microbial activity might be expected in the proximity of a geological repository i.e., in the excavation damaged zone, the engineered barriers, and first containments (the containers). (authors)

  9. Fifteen years of microbiological investigation in Opalinus Clay at the Mont Terri rock laboratory (Switzerland)

    Leupin, O.X.; Bernier-Latmani, R.; Bagnoud, A.; Moors, H.; Leys, N.; Wouters, K.; Stroes-Gascoyne, S.

    2017-01-01

    Microbiological studies related to the geological disposal of radioactive waste have been conducted at the Mont Terri rock laboratory in Opalinus Clay, a potential host rock for a deep geologic repository, since 2002. The metabolic potential of microorganisms and their response to excavation-induced effects have been investigated in undisturbed and disturbed claystone cores and in pore- (borehole) water. Results from nearly 15 years of research at the Mont Terri rock laboratory have shown that microorganisms can potentially affect the environment of a repository by influencing redox conditions, metal corrosion and gas production and consumption under favourable conditions. However, the activity of microorganisms in undisturbed Opalinus Clay is limited by the very low porosity, the low water activity, and the largely recalcitrant nature of organic matter in the claystone formation. The presence of microorganisms in numerous experiments at the Mont Terri rock laboratory has suggested that excavation activities and perturbation of the host rock combined with additional contamination during the installation of experiments in boreholes create favourable conditions for microbial activity by providing increased space, water and substrates. Thus effects resulting from microbial activity might be expected in the proximity of a geological repository i.e., in the excavation damaged zone, the engineered barriers, and first containments (the containers). (authors)

  10. Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland

    Senger, R.; Marschall, P.; Finsterle, S.

    2008-01-01

    Gas generation from corrosion of the waste canisters and gas accumulation in the backfilled emplacement tunnels is a key issue in the assessment of long-term radiological safety of the proposed repository for spent fuel and high-level waste (SF/HLW) sited in the Opalinus Clay formation of Northern Switzerland. Previous modeling studies indicated a significant pressure buildup in the backfilled emplacement tunnels for those sensitivity runs, where corrosion rates were high and the permeability of the Opalinus Clay was very low. As an extension to those studies, a refined process model of the canister corrosion phenomena has been developed, which accounts not only for the gas generation but also for the water consumption associated with the chemical reaction of corrosion of steel under anaerobic conditions. The simulations with the new process model indicate, that with increasing corrosion rates and decreasing host-rock permeability, pressure buildup increased, as expected. However, the simulations taking into account water consumption show that the pressure buildup is reduced compared to the simulation considering only gas generation. The pressure reduction is enhanced for lower permeability of the Opalinus Clay and for higher corrosion rates, which correspond to higher gas generations rates and higher water consumption rates. Moreover, the simulated two-phase flow patterns in the engineered barrier system (EBS) and surrounding Opalinus Clay show important differences at late time of the gas production phase as the generated gas continues to migrate outward into the surrounding host rock. For the case without water consumption, the water flow indicates overall downward flow due to a change in the overall density of the gas-fluid mixture from that based on the initially prescribed hydrostatic pressure gradient. For the case with water consumption, water flow converges toward the waste canister at a rate corresponding to the water consumption rate associated with the

  11. In situ analysis of microbial reduction of a nitrate plume in Opalinus clay

    Bleyen, N.; Smets, S.; Valcke, E.; Albrecht, A.; De Canniere, P.; Schwyn, B.; Wittebroodt, C.

    2012-01-01

    Document available in extended abstract form only. In several countries, such as Belgium, France and Switzerland, clay formations are foreseen as the host rock for geological disposal of bituminized low-level and intermediate-level long-lived radioactive waste. Suitable clay formations exhibit favorable hydro-mechanical and geochemical characteristics, which are expected to retard the migration of leached radionuclides. Along with radionuclides, certain classes of bituminized radioactive waste may also contain high concentrations of NaNO 3 , dispersed into the hydrophobic bitumen matrix used to stabilize the waste. During and after saturation of the disposal gallery, this bituminized waste will start to take up water due to osmosis, resulting in the leaching of significant amounts of NaNO 3 and soluble organic bitumen degradation products (BDP) into the clay pore water. This nitrate plume could cause several geochemical and biochemical processes in the clay surrounding the waste disposal gallery, potentially affecting the barrier function of the host rock. To study these processes, an in situ experiment in the Opalinus Clay, named the Bitumen-Nitrate-Clay interaction (BN) experiment, is being performed at the Mont Terri Rock Laboratory (CH). The experiment consists of a vertical borehole rigged with a downhole equipment containing three packed-off intervals, each lined with a cylindrical sintered stainless steel filter screen to allow contact with the surrounding clay. Prior to the start of the tests, the intervals were injected with an artificial Opalinus Clay pore water, containing all major ions at pore water concentrations at Mont Terri, but no organic matter, and were equilibrated with the surrounding clay for ∼8 months. To ensure a continuous water flow during the tests, each interval is connected to a stainless steel water circulation unit, equipped with water sampling containers, circulation pumps and flow meters. In addition, to continuously monitor the

  12. Comparative study of methods to estimate hydraulic parameters in the hydraulically undisturbed Opalinus Clay (Switzerland)

    Yu, C.; Matray, J.-M. [Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, (France); Yu, C.; Gonçalvès, J. [Aix Marseille Université UMR 6635 CEREGE Technopôle Environnement Arbois-Méditerranée Aix-en-Provence, Cedex 4 (France); and others

    2017-04-15

    The deep borehole (DB) experiment gave the opportunity to acquire hydraulic parameters in a hydraulically undisturbed zone of the Opalinus Clay at the Mont Terri rock laboratory (Switzerland). Three methods were used to estimate hydraulic conductivity and specific storage values of the Opalinus Clay formation and its bounding formations through the 248 m deep borehole BDB-1: application of a Poiseuille-type law involving petrophysical measurements, spectral analysis of pressure time series and in situ hydraulic tests. The hydraulic conductivity range in the Opalinus Clay given by the first method is 2 × 10{sup -14}-6 × 10{sup -13} m s{sup -1} for a cementation factor ranging between 2 and 3. These results show low vertical variability whereas in situ hydraulic tests suggest higher values up to 7 × 10{sup -12} m s{sup -1}. Core analysis provides economical estimates of the homogeneous matrix hydraulic properties but do not account for heterogeneities at larger scale such as potential tectonic conductive features. Specific storage values obtained by spectral analysis are consistent and in the order of 10{sup -6} m{sup -1}, while formulations using phase shift and gain between pore pressure signals were found to be inappropriate to evaluate hydraulic conductivity in the Opalinus Clay. The values obtained are globally in good agreement with the ones obtained previously at the rock laboratory. (authors)

  13. Mont Terri project, cyclic deformations in the Opalinus Clay

    Moeri, A.; Bossart, P.; Matray, J.M.; Mueller, H.; Frank, E.

    2010-01-01

    Document available in extended abstract form only. Shrinkage structures in the Opalinus Clay, related to seasonal changes in temperature and humidity, are observed on the tunnel walls of the Mont Terri Rock Laboratory. The structures open in winter, when relative humidity in the tunnel decreases to 65%. In summer the cracks close again because of the increase in the clay volume when higher humidity causes rock swelling. Shrinkage structures are monitored in the Mont Terri Rock Laboratory at two different sites within the undisturbed rock matrix and a major fault zone. The relative movements of the rock on both sides of the cracks are monitored in three directions and compared to the fluctuations in ambient relative humidity and temperature. The cyclic deformations (CD) experiment aims to quantify the variations in crack opening in relation to the evolution of climatic conditions and to identify the processes underlying these swell and shrinkage cycles. It consists of the following tasks: - Measuring and quantifying the long-term (now up to three yearly cycles) opening and closing and, if present, the associated shear displacements of selected shrinkage cracks along an undisturbed bedding plane as well as within a major fault zone ('Main Fault'). The measurements are accompanied by temperature and humidity records as well as by a long-term monitoring of tunnel convergence. - Analysing at the micro-scale the surfaces of the crack planes to identify potential relative movements, changes in the rock fabric on the crack surfaces and the formation of fault gouge material as observed in closed cracks. - Processing and analysing measured fluctuations of crack apertures and rock deformation in the time series as well as in the hydro-meteorological variables, in particular relative humidity Hr(t) and air temperature. - Studying and reconstructing the opening cycles on a drill-core sample under well-known laboratory conditions and observing potential propagation of

  14. Biogeochemical processes in a clay formation in situ experiment: Part E - Equilibrium controls on chemistry of pore water from the Opalinus Clay, Mont Terri Underground Research Laboratory, Switzerland

    Pearson, F.J., E-mail: fjpearson@gmail.com [Ground-Water Geochemistry, 5108 Trent Woods Dr., New Bern, NC 28562 (United States); Tournassat, Christophe; Gaucher, Eric C. [BRGM, B.P. 36009, 45060 Orleans Cedex 2 (France)

    2011-06-15

    Highlights: > Equilibrium models of water-rock reactions in clay rocks are reviewed. > Analyses of pore waters of the Opalinus Clay from boreholes in the Mont Terri URL, Switzerland, are tabulated. > Results of modelling with various mineral controls are compared with the analyses. > Best agreement results with calcite, dolomite and siderite or daphnite saturation, Na-K-Ca-Mg exchange and/or kaolinite, illite, quartz and celestite saturation. > This approach allows calculation of the chemistry of pore water in clays too impermeable to yield water samples. - Abstract: The chemistry of pore water (particularly pH and ionic strength) is an important property of clay rocks being considered as host rocks for long-term storage of radioactive waste. Pore waters in clay-rich rocks generally cannot be sampled directly. Instead, their chemistry must be found using laboratory-measured properties of core samples and geochemical modelling. Many such measurements have been made on samples from the Opalinus Clay from the Mont Terri Underground Research Laboratory (URL). Several boreholes in that URL yielded water samples against which pore water models have been calibrated. Following a first synthesis report published in 2003, this paper presents the evolution of the modelling approaches developed within Mont Terri URL scientific programs through the last decade (1997-2009). Models are compared to the composition of waters sampled during dedicated borehole experiments. Reanalysis of the models, parameters and database enabled the principal shortcomings of the previous modelling efforts to be overcome. The inability to model the K concentrations correctly with the measured cation exchange properties was found to be due to the use of an inappropriate selectivity coefficient for Na-K exchange; the inability to reproduce the measured carbonate chemistry and pH of the pore waters using mineral-water reactions alone was corrected by considering clay mineral equilibria. Re

  15. Experiments on thermo-hydro-mechanical behaviour of Opalinus Clay at Mont Terri rock laboratory, Switzerland

    Paul Bossart

    2017-06-01

    Full Text Available Repositories for deep geological disposal of radioactive waste rely on multi-barrier systems to isolate waste from the biosphere. A multi-barrier system typically comprises the natural geological barrier provided by the repository host rock – in our case the Opalinus Clay – and an engineered barrier system (EBS. The Swiss repository concept for spent fuel and vitrified high-level waste (HLW consists of waste canisters, which are emplaced horizontally in the middle of an emplacement gallery and are separated from the gallery wall by granular backfill material (GBM. We describe here a selection of five in-situ experiments where characteristic hydro-mechanical (HM and thermo-hydro-mechanical (THM processes have been observed. The first example is a coupled HM and mine-by test where the evolution of the excavation damaged zone (EDZ was monitored around a gallery in the Opalinus Clay (ED-B experiment. Measurements of pore-water pressures and convergences due to stress redistribution during excavation highlighted the HM behaviour. The same measurements were subsequently carried out in a heater test (HE-D where we were able to characterise the Opalinus Clay in terms of its THM behaviour. These yielded detailed data to better understand the THM behaviours of the granular backfill and the natural host rock. For a presentation of the Swiss concept for HLW storage, we designed three demonstration experiments that were subsequently implemented in the Mont Terri rock laboratory: (1 the engineered barrier (EB experiment, (2 the in-situ heater test on key-THM processes and parameters (HE-E experiment, and (3 the full-scale emplacement (FE experiment. The first demonstration experiment has been dismantled, but the last two ones are on-going.

  16. Diffusion Experiments in Opalinus Clay: Laboratory, Large-Scale Diffusion Experiments and Microscale Analysis by RBS.

    Garcia-Gutierrez, M.; Alonso de los Rios, U.; Missana, T.; Cormenzana, J.L.; Mingarro, M.; Morejon, J.; Gil, P.

    2008-08-06

    The Opalinus Clay (OPA) formation in the Zurcher Weiland (Switzerland) is a potential host rock for a repository for high-level radioactive waste. Samples collected in the Mont Terri Underground Rock Laboratory (URL), where the OPA formation is located at a depth between -200 and -300 m below the surface, were used to study the radionuclide diffusion in clay materials. Classical laboratory essays and a novel experimental set-up for large-scale diffusion experiments were performed together to a novel application of the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS), to understand the transport properties of the OPA and to enhance the methodologies used for in situ diffusion experiments. Through-Diffusion and In-Diffusion conventional laboratory diffusion experiments were carried out with HTO, 36{sup C}l-, I-, 22{sup N}a, 75{sup S}e, 85{sup S}r, 233{sup U}, 137{sup C}s, 60{sup C}o and 152{sup E}u. Large-scale diffusion experiments were performed with HTO, 36{sup C}l, and 85{sup S}r, and new experiments with 60{sup C}o, 137{sup C}s and 152{sup E}u are ongoing. Diffusion experiments with RBS technique were done with Sr, Re, U and Eu. (Author) 38 refs.

  17. Physico-chemical characterisation and sorption measurements of Cs, Sr, Ni, Eu, Th, Sn and Se on Opalinus clay from Mont Terri

    Lauber, Matthias; Baeyens, Bart; Bradbury, Michael H.

    2000-12-01

    Opalinus Clay is currently under investigation as a potential host rock for the disposal of high level and long-lived intermediate radioactive waste. A throughout physico-chemical characterisation was carried out on a bore core sample from the underground rock laboratory Mont Terri (Canton Jura). The results of these investigations indicate that the major characteristics (mineralogy, cation exchange capacity, cation occupancies, selectivity coefficients, chloride and sulphate inventories) were very similar to a different core sample, previously used for pore water modelling studies. It was concluded that the pore water compositions derived in the earlier studies were reliable and could be used in this work. The organic matter which dissolved from the Opalinus Clay rock was not humic or fulvic acids and the concentration remaining in the liquid phase in the sorption experiments was < 0.5 ppm C. The organic matter is therefore considered to have little or no influence on the sorption behaviour of the studied radionuclides. Redox potential measurements of the Opalinus Clay/synthetic pore water system inside the glove boxes indicated anoxic conditions. The main focus of the experimental work presented here is on the sorption behaviour of Cs (I), Sr (II), Ni (II), Eu (III), Th (IV), Sn (IV) and Se (IV) on Opalinus Clay equilibrated with synthetic pore waters at pH 6.3 and 8. Sorption isotherms were measured for Cs, Ni, Eu, Th and Se. Single point data were measured for Sr and Sn. For all radionuclides studied the sorption kinetics were measured first. The times required to complete the sorption on the Opalinus Clay varied between one day for Th and one month for Ni and Se. Within the concentration ranges under study the uptake of Cs, Ni, Eu and Se on Opalinus Clay was non-linear, whereas for Th a linear sorption behaviour was observed. For Ni, Eu and Th the sorption increased with increasing pH. For Cs a pH independent sorption behaviour was observed. The concentration

  18. Hydrogeology of a fractured shale (Opalinus Clay): Implications for deep geological disposal of radioactive wastes

    Gautschi, Andreas

    2001-01-01

    As part of the Swiss programme for high-level radioactive-waste disposal, a Jurassic shale (Opalinus Clay) is being investigated as a potential host rock. Observations in clay pits and the results of a German research programme focusing on hazardous waste disposal have demonstrated that, at depths of 10-30 m, the permeability of the Opalinus Clay decreases by several orders of magnitude. Hydraulic tests in deeper boreholes (test intervals below 300 m) yielded hydraulic conductivities Las observaciones efectuadas en pozos en arcilla y los resultados de un programa de estudio alemán sobre eliminación de residuos peligrosos han demostrado que, a profundidades de entre 10 y 30 m, la permeabilidad de la Arcilla Opalina decrece en varios órdenes de magnitud. Los ensayos hidráulicos realizados en sondeos más profundos (en intervalos situados a más de 300 m) proporcionaron conductividades hidráulicas inferiores a 10-12 m/s, pese a que algunos de los intervalos interceptaban juntas y fallas. Estas medidas son coherentes con los datos hidrogeológicos de las secciones de Arcilla Opalina existentes en 10 túneles del Jurásico Plegado, al norte de Suiza. A pesar de las fallas extensivas, apenas se hallaron indicios de entrada de agua en los más de 6.600 m de túnel. Todos los flujos tenían lugar en secciones del túnel que soportan sobrecargas inferiores a 200 m. Los datos hidráulicos son coherentes con los datos hidroquímicos e isotópicos del agua intersticial de las arcillas. Los abundantes datos hidrogeológicos -parte de los cuales proceden de medios particularmente desfavorables desde el punto de vista geológico- proporcionan argumentos de que el transporte advectivo a través de fallas y juntas no es un aspecto crítico en lo que respecta a la idoneidad de la Arcilla Opalina como almacenamiento geológico profundo de residuos.

  19. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-01-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  20. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-07-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  1. Microbiological analysis of the in situ bitumen-nitrate-Opalinus clay interaction

    Moors, Hugo; Boven, Patrick; Leys, Natalie; Geissler, Andrea; Selenska-Pobell, Sonja

    2012-01-01

    Document available in extended abstract form only. Clay formations like the Opalinus Clay are foreseen to serve as the host rock for geological disposal of high and intermediate-level long-lived radioactive waste in several countries, because of their favourable properties to delay the migration of radionuclides over time. However, bituminized intermediate-level long-lived radioactive waste may physico-chemically perturb the clay barrier properties because in time it will leach substantial amounts of nitrate and organic bitumen degradation products (BDP). To study the physico-chemical impact of intermediate-level radioactive waste containing bitumen and nitrate, an in situ experiment in the Opalinus Clay (Saint Ursanne, Switzerland) named the Bitumen-Nitrate- Clay interaction (BN) experiment, is being performed at the Mont Terri Rock Laboratory. The in situ equipment of the BN-experiment consists of three separate packed-off intervals, supplied with a filter screen. Each interval is equipped with its own stainless steel water circulation unit. Such water circulation unit contains water sampling containers, circulation pumps and flow meters. One of the circulation units is equipped with an on-line UV spectrophotometer and pH electrode intervals, allowing a continuous monitoring of nitrate, nitrite concentrations, organic carbon level and pH. In a first series of tests, the microbial and biogeochemical effect of a nitrate and/or acetate perturbation is studied. Acetate is used as it a good representation of BDP. Hereto, nitrate was injected in interval 1 while a mixture of nitrate and acetate is injected in interval 2. As an active microbial community can have a significant impact on the physical and (geo)chemical conditions of the clay surrounding the disposal gallery, microbial analyses were performed on samples taken from the interval solutions before, during and after this first series of tests. Our microbial investigations which included Scanning Electron

  2. Microbiological analysis of the in situ bitumen-nitrate-Opalinus clay interaction

    Moors, Hugo; Boven, Patrick; Leys, Natalie [SCK.CEN, Institute for Environment, Health and Safety, Laboratory for Molecular and Cellular Biology, Boeretang 200, B-2400 MOL (Belgium); Geissler, Andrea; Selenska-Pobell, Sonja [Helmholtz Zentrum Dresden Rossendorf, Institute of Radiochemistry, Biogeochemistry, Bautzner Landstr. 400, D-01328 Dresden (Germany)

    2012-10-15

    Document available in extended abstract form only. Clay formations like the Opalinus Clay are foreseen to serve as the host rock for geological disposal of high and intermediate-level long-lived radioactive waste in several countries, because of their favourable properties to delay the migration of radionuclides over time. However, bituminized intermediate-level long-lived radioactive waste may physico-chemically perturb the clay barrier properties because in time it will leach substantial amounts of nitrate and organic bitumen degradation products (BDP). To study the physico-chemical impact of intermediate-level radioactive waste containing bitumen and nitrate, an in situ experiment in the Opalinus Clay (Saint Ursanne, Switzerland) named the Bitumen-Nitrate- Clay interaction (BN) experiment, is being performed at the Mont Terri Rock Laboratory. The in situ equipment of the BN-experiment consists of three separate packed-off intervals, supplied with a filter screen. Each interval is equipped with its own stainless steel water circulation unit. Such water circulation unit contains water sampling containers, circulation pumps and flow meters. One of the circulation units is equipped with an on-line UV spectrophotometer and pH electrode intervals, allowing a continuous monitoring of nitrate, nitrite concentrations, organic carbon level and pH. In a first series of tests, the microbial and biogeochemical effect of a nitrate and/or acetate perturbation is studied. Acetate is used as it a good representation of BDP. Hereto, nitrate was injected in interval 1 while a mixture of nitrate and acetate is injected in interval 2. As an active microbial community can have a significant impact on the physical and (geo)chemical conditions of the clay surrounding the disposal gallery, microbial analyses were performed on samples taken from the interval solutions before, during and after this first series of tests. Our microbial investigations which included Scanning Electron

  3. The Mont Terri rock laboratory: International research in the Opalinus Clay

    Bossart, P.

    2015-01-01

    This article reports on a visit made to the rock laboratory in Mont Terri, Switzerland, where research is being done concerning rock materials that can possibly be used for the implementation of repositories for nuclear wastes. Emphasis is placed on the project’s organisation, rock geology and on-going experiments. International organisations also involved in research on nuclear waste repositories are listed. The research facilities in tunnels built in Opalinus Clay at the Mont Terri site are described. The geology of Opalinus Clay and the structures found in the research tunnels are discussed, as is the hydro-geological setting. The research programme and various institutions involved are listed and experiments carried out are noted. The facilities are now also being used for research on topics related to carbon sequestration

  4. Self-sealing Faults in the Opalinus Clay - Evidence from Field Observations, Hydraulic Testing and Pore water Chemistry

    Gautschi, Andreas

    2001-01-01

    As part of the Swiss programme for high-level radioactive-waste, the National Cooperative for the Disposal of Radioactive Waste (Nagra) is currently investigating the Jurassic (Aalenian) Opalinus Clay as a potential host formation (Nagra 1988, 1994). The Opalinus Clay consists of indurated dark grey micaceous Clay-stones (shales) that are subdivided into several litho-stratigraphic units. Some of them contain thin sandy lenses, limestone concretions or siderite nodules. The clay mineral content ranges from 40-80 weight per cent (9-29% illite, 3-10% chlorite, 6-20% kaolinite and 4-22% illite/smectite mixed layers in the ratio 70/30). Other minerals are quartz (15-30%), calcite (6-40%), siderite (2-3%), ankerite (0-3%), feldspars (1-7%), pyrite (1-3%) and organic carbon (<1%). The total water content ranges from 4-19% (Mazurek 1999, Nagra 2001). Faults are mainly represented by fault gouge and fault breccias, partly associated with minor veins of calcite. A key question in safety assessment is, whether these faults may represent preferential pathways for radionuclide transport. An extensive hydrogeological data base - part of which derives from strongly tectonized geological environments - suggests that advective transport through faults in the Opalinus Clay at depth > 200 m is insignificant. This conclusion is also supported by independent evidence from clay pore water hydrochemical and isotopic data. The lack of hydrochemical anomalies and the lack of extensive mineral veining suggest that there was also no significant paleo-flow through such faults. These observations can only be reconciled with a strong self-sealing capacity of the faults. Therefore it is concluded, that reactivated existing faults or newly induced fractures will not act as pathways for significant fluid flow at anytime due to self-healing processes. These conclusions are supported by results from laboratory hydro-frac and flow-through tests, and from field-tests in the Mont Terri underground

  5. Diffusion Experiments with Opalinus and Callovo-Oxfordian Clays: Laboratory, Large-Scale Experiments and Microscale Analysis by RBS

    Garcia-Gutierrez, M.; Alonso, U.; Missana, T.; Cormenzana, J.L.; Mingarro, M.; Morejon, J.; Gil, P.

    2009-01-01

    Consolidated clays are potential host rocks for deep geological repositories for high-level radioactive waste. Diffusion is the main transport process for radionuclides (RN) in these clays. Radionuclide (RN) diffusion coefficients are the most important parameters for Performance Assessment (PA) calculations of clay barriers. Different diffusion methodologies were applied at a laboratory scale to analyse the diffusion behaviour of a wide range of RN. Main aims were to understand the transport properties of different RNs in two different clays and to contribute with feasible methodologies to improve in-situ diffusion experiments, using samples of larger scale. Classical laboratory essays and a novel experimental set-up for large-scale diffusion experiments were performed, together to a novel application of the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS), for diffusion analyses at the micrometer scale. The main experimental and theoretical characteristics of the different methodologies, and their advantages and limitations are here discussed. Experiments were performed with the Opalinus and the Callovo-Oxfordian clays. Both clays are studied as potential host rock for a repository. Effective diffusion coefficients ranged between 1.10 - 10 to 1.10 - 12 m 2 /s for neutral, low sorbing cations (as Na and Sr) and anions. Apparent diffusion coefficients for strongly sorbing elements, as Cs and Co, are in the order of 1.10-13 m 2 /s; europium present the lowest diffusion coefficient (5.10 - 15 m 2 /s). The results obtained by the different approaches gave a comprehensive database of diffusion coefficients for RN with different transport behaviour within both clays. (Author) 42 refs

  6. Diffusion Experiments with Opalinus and Callovo-Oxfordian Clays: Laboratory, Large-Scale Experiments and Microscale Analysis by RBS

    Garcia-Gutierrez, M.; Alonso, U.; Missana, T.; Cormenzana, J.L.; Mingarro, M.; Morejon, J.; Gil, P.

    2009-09-25

    Consolidated clays are potential host rocks for deep geological repositories for high-level radioactive waste. Diffusion is the main transport process for radionuclides (RN) in these clays. Radionuclide (RN) diffusion coefficients are the most important parameters for Performance Assessment (PA) calculations of clay barriers. Different diffusion methodologies were applied at a laboratory scale to analyse the diffusion behaviour of a wide range of RN. Main aims were to understand the transport properties of different RNs in two different clays and to contribute with feasible methodologies to improve in-situ diffusion experiments, using samples of larger scale. Classical laboratory essays and a novel experimental set-up for large-scale diffusion experiments were performed, together to a novel application of the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS), for diffusion analyses at the micrometer scale. The main experimental and theoretical characteristics of the different methodologies, and their advantages and limitations are here discussed. Experiments were performed with the Opalinus and the Callovo-Oxfordian clays. Both clays are studied as potential host rock for a repository. Effective diffusion coefficients ranged between 1.10{sup -}10 to 1.10{sup -}12 m{sup 2}/s for neutral, low sorbing cations (as Na and Sr) and anions. Apparent diffusion coefficients for strongly sorbing elements, as Cs and Co, are in the order of 1.10-13 m{sup 2}/s; europium present the lowest diffusion coefficient (5.10{sup -}15 m{sup 2}/s). The results obtained by the different approaches gave a comprehensive database of diffusion coefficients for RN with different transport behaviour within both clays. (Author) 42 refs.

  7. Ventilation test at Mont Terri. Geoelectric monitoring of the opalinus clay desaturation. Phase 2

    Wieczorek, Klaus; Zhang, Chun-Liang; Rothfuchs, Tilmann

    2008-04-01

    Between December 2001 and May 2004, a ventilation experiment (VE) was performed in the Mont Terri Underground Research Laboratory (URL) and co-financed by the Commission of the European Communities. The objective was to investigate the desaturation of consolidated clay formations in consequence of the ventilation of underground openings of a repository in such a formation. The results of the geoelectric measurements performed in the second phase of the Mont Terri ventilation test can be summarized as follows: Geoelectric tomography has been found suitable for monitoring ventilation-induced saturation changes in the Opalinus clay. During ventilation with dry air a desaturation down to below 50% could be detected in both desaturation cycles. The desaturated zone extends less than 0.5 m into the rock around the microtunnel. During the second resaturation phase, ventilation with humid air led to quick resaturation at the tunnel surface, while resaturation of the rock mass took months. The still ongoing third resaturation phase seems to imply that resaturation of the rock mass may take years with no air circulation in the tunnel. The laboratory investigations on the Opalinus clay included the determination of water retention capacity, swelling pressure, free swelling/shrinking strains induced by moisture changes, and response of normal and large hollow clay samples to the ventilation of the central boreholes at different air humidity values. The Opalinus clay has a high water absorption capacity. The amount of water uptake in unconstraint conditions is much higher than the water content in the naturally confined state, indicating that the pore water in the natural clay rock is predominantly bound on clay minerals. The swelling pressure induced by wetting with vapour is very close to the major lithostatic stress at the sampling location. Water uptake from vapour causes a large free expansion of up to 12% over 8 months and even a breakdown along bedding planes. Release of

  8. Anisotropic Diffusion In Layered Argillaceous Rocks: A Case Study With Opalinus Clay

    Van Loon, L.R.; Soler, J.; Mueller, W.; Bradbury, M.H.

    2003-01-01

    Anisotropic diffusion was studied in Opalinus Clay, a potential host rock for the disposal of spent fuel, vitrified high-level waste and intermediate-level waste. Diffusion parallel to the bedding was measured using a radial through-diffusion technique, while diffusion perpendicular to the bedding was measured using the classical (planar) through-diffusion method. The materials used were samples from Mont Terri (MT) and Benken (BE), respectively. Diffusion of Tritiated Water (HTO), parallel and perpendicular to the bedding, was studied under confining pressures of 7 MPa (MT) and 14 MPa (BE), respectively. The effective diffusion coefficient for diffusion parallel to the bedding, D e , was found to be 3.20(±0.26)x10 11 m 2 s -1 and for the Benken 5.39(±0.43)x10 -11 m 2 s-1 for the Mont Terri samples. The diffusion accessible porosity was ∼ 0.15(±0.02) in both cases. For diffusion perpendicular to the bedding, the effective diffusion coefficient was 5.44(±0.35)x10 -12 m 2 s-1 and 1.37(±0.08)x10 -11 m 2 s -1 for the Benken and Mont Terri samples, respectively. The diffusion accessible porosity was also ∼0.15(±0.02) in both cases. These first results indicate that diffusion parallel to bedding is larger than that perpendicular to the bedding by a factor of 4 to 6. This might be explained in terms of smaller path lengths (tortuosity) for species diffusing parallel to the fabric. (author)

  9. Anisotropic Diffusion In Layered Argillaceous Rocks: A Case Study With Opalinus Clay

    Van Loon, L.R.; Soler, J.; Mueller, W.; Bradbury, M.H

    2003-03-01

    Anisotropic diffusion was studied in Opalinus Clay, a potential host rock for the disposal of spent fuel, vitrified high-level waste and intermediate-level waste. Diffusion parallel to the bedding was measured using a radial through-diffusion technique, while diffusion perpendicular to the bedding was measured using the classical (planar) through-diffusion method. The materials used were samples from Mont Terri (MT) and Benken (BE), respectively. Diffusion of Tritiated Water (HTO), parallel and perpendicular to the bedding, was studied under confining pressures of 7 MPa (MT) and 14 MPa (BE), respectively. The effective diffusion coefficient for diffusion parallel to the bedding, D{sub e}, was found to be 3.20({+-}0.26)x10{sup 11} m{sup 2}s{sup -1} and for the Benken 5.39({+-}0.43)x10{sup -11} m{sup 2}s-1 for the Mont Terri samples. The diffusion accessible porosity was {approx} 0.15({+-}0.02) in both cases. For diffusion perpendicular to the bedding, the effective diffusion coefficient was 5.44({+-}0.35)x10{sup -12} m{sup 2}s-1 and 1.37({+-}0.08)x10{sup -11} m{sup 2}s{sup -1} for the Benken and Mont Terri samples, respectively. The diffusion accessible porosity was also {approx}0.15({+-}0.02) in both cases. These first results indicate that diffusion parallel to bedding is larger than that perpendicular to the bedding by a factor of 4 to 6. This might be explained in terms of smaller path lengths (tortuosity) for species diffusing parallel to the fabric. (author)

  10. Geomechanical behaviour of Opalinus Clay at multiple scales: results from Mont Terri rock laboratory (Switzerland)

    Amann, F.; Wild, K.M.; Loew, S. [Institute of Geology, Engineering Geology, Swiss Federal Institute of Technology, Zurich (Switzerland); Yong, S. [Knight Piesold Ltd, Vancouver (Canada); Thoeny, R. [Grundwasserschutz und Entsorgung, AF-Consult Switzerland AG, Baden (Switzerland); Frank, E. [Sektion Geologie (GEOL), Eidgenössisches Nuklear-Sicherheitsinspektorat (ENSI), Brugg (Switzerland)

    2017-04-15

    The paper represents a summary about our research projects conducted between 2003 and 2015 related to the mechanical behaviour of Opalinus Clay at Mont Terri. The research summarized covers a series of laboratory and field tests that address the brittle failure behaviour of Opalinus Clay, its undrained and effective strength, the dependency of petro-physical and mechanical properties on total suction, hydro-mechanically coupled phenomena and the development of a damage zone around excavations. On the laboratory scale, even simple laboratory tests are difficult to interpret and uncertainties remain regarding the representativeness of the results. We show that suction may develop rapidly after core extraction and substantially modifies the strength, stiffness, and petro-physical properties of Opalinus Clay. Consolidated undrained tests performed on fully saturated specimens revealed a relatively small true cohesion and confirmed the strong hydro-mechanically coupled behaviour of this material. Strong hydro-mechanically coupled processes may explain the stability of cores and tunnel excavations in the short term. Pore-pressure effects may cause effective stress states that favour stability in the short term but may cause longer-term deformations and damage as the pore-pressure dissipates. In-situ observations show that macroscopic fracturing is strongly influenced by bedding planes and faults planes. In tunnel sections where opening or shearing along bedding planes or faults planes is kinematically free, the induced fracture type is strongly dependent on the fault plane frequency and orientation. A transition from extensional macroscopic failure to shearing can be observed with increasing fault plane frequency. In zones around the excavation where bedding plane shearing/shearing along tectonic fault planes is kinematically restrained, primary extensional type fractures develop. In addition, heterogeneities such as single tectonic fault planes or fault zones

  11. Excavation induced damage evolution during a mine-by experiment in Opalinus Clay

    Vietor, T.; Armand, G.; Nyonoya, S.; Schuster, K.; Wieczorek, K.

    2010-01-01

    Document available in extended abstract form only. In Switzerland Opalinus Clay, a potential host rock formation for a nuclear waste repository, is intensively studied in the Mont Terri Underground Rock Laboratory (URL) in North-Western Switzerland. During the 2008 extension of the URL, the construction works were repeatedly interrupted to implement monitoring systems for a mine-by experiment. The future position of a 24 m long tunnel was instrumented with 36 different monitoring systems comprising approximately 200 sensors. Key features of this tunnel were chosen similar to the current Swiss concept for emplacement tunnels for High Level Radioactive Waste: circular section, full-face excavation following the geological bedding, support by a thin layer of shotcrete and 6 anchors every 1.3 m. For a mine-by experiment 26 boreholes were equipped with 7 multipoint extensometers, two multi segment inclinometer chains and 26 pore pressure chambers. The data acquisition system recorded 12 data sets per hour. For seismic transmission and acoustic emission monitoring, 8 piezo-electric emitters and 15 piezo-electric receivers were installed in 5 boreholes. The excavation of the instrumented tunnel took place in October/November 2008. The activities on the site were monitored with a web cam to separate spontaneous and excavation induced rock mass reactions. Daily mappings of the tunnel face and the sidewalls revealed the fracture pattern that was generated ahead of the advancing excavation. Three sets of excavation activated discontinuities could be clearly identified. These three sets develop within the framework of the pre-existing tectonic micro-faults that generally have a half-meter spacing. Where their density is high the intensity of excavation induced new slip planes apparently drops. Despite the presence of micro-faults the deformation monitoring around the advancing tunnel face showed a remarkably homogenous response to the excavation. Inclinometer chain segments

  12. Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland)

    Bleyen, N.; Smets, S. [Belgian Nuclear Research Centre SCK-CEN, Mol (Belgium); Small, J. [National Nuclear Laboratory NLL, Warrington (United Kingdom); and others

    2017-04-15

    At the Mont Terri rock laboratory (Switzerland), an in situ experiment is being carried out to examine the fate of nitrate leaching from nitrate-containing bituminized radioactive waste, in a clay host rock for geological disposal. Such a release of nitrate may cause a geochemical perturbation of the clay, possibly affecting some of the favorable characteristics of the host rock. In this in situ experiment, combined transport and reactivity of nitrate is studied inside anoxic and water-saturated chambers in a borehole in the Opalinus Clay. Continuous circulation of the solution from the borehole to the surface equipment allows a regular sampling and online monitoring of its chemical composition. In this paper, in situ microbial nitrate reduction in the Opalinus Clay is discussed, in the presence or absence of additional electron donors relevant for the disposal concept and likely to be released from nitrate-containing bituminized radioactive waste: acetate (simulating bitumen degradation products) and H{sub 2} (originating from radiolysis and corrosion in the repository). The results of these tests indicate that - in case microorganisms would be active in the repository or the surrounding clay - microbial nitrate reduction can occur using electron donors naturally present in the clay (e.g. pyrite, dissolved organic matter). Nevertheless, non-reactive transport of nitrate in the clay is expected to be the main process. In contrast, when easily oxidizable electron donors would be available (e.g. acetate and H{sub 2}), the microbial activity will be strongly stimulated. Both in the presence of H{sub 2} and acetate, nitrite and nitrogenous gases are predominantly produced, although some ammonium can also be formed when H{sub 2} is present. The reduction of nitrate in the clay could have an impact on the redox conditions in the pore-water and might also lead to a gas-related perturbation of the host rock, depending on the electron donor used during denitrification

  13. Time-dependent Flow and Transport Calculations for Project Opalinus Clay (Entsorgungsnachweis)

    Kosakowski, G.

    2004-07-01

    This report describes two specific assessment cases used in the safety assessment for a proposed deep geological repository for spent fuel, high level waste and long-lived intermediate-level waste, sited in the Opalinus Clay of the Zuercher Weinland in northern Switzerland (Project Entsorgungsnachweis, NAG RA, 2002d). In this study the influence of time dependent flow processes on the radionuclide transport in the geosphere is investigated. In the Opalinus Clay diffusion dominates the transport of radionuclides, but processes exist that can locally increase the importance of the advective transport for some time. Two important cases were investigated: (1) glaciation-induced flow due to an additional overburden in the form of an ice shield of up to 400 m thickness and (2) fluid flow driven by tunnel convergence. For the calculations the code FRAC3DVS (Therrien and Sudicky, 1996) was used. FRAC3DVS solves the three-dimensional flow and transport equation in porous and fractured media. For the case of glaciation-induced flow (1) a two-dimensional reference model without glaciations was calculated. During the glaciations the geosphere release-rates are up to a factor of about 1.7 higher compared to the reference model. The influence of glaciations on the transport of cations or neutral species is less than for anions, since the importance of the advective transport for anions is higher due to the lower accessible porosity for anions. The increase in the release rates during glaciations is lower for sorbing compared to non-sorbing radionuclides. The influence of the tunnel convergence (2) on the transport of radionuclides in the geosphere is very small. Due to the higher source term the geosphere release rates are slightly higher if tunnel convergence is considered. In addition to the two assessment cases this report investigates the applicability of the one-dimensional approximation for modelling transport through the Opalinus Clay. For the reference case of the safety

  14. Three-dimensional FDEM numerical simulation of failure processes observed in Opalinus Clay laboratory samples

    Omid Mahabadi

    2014-12-01

    Full Text Available This study presents the first step of a research project that aims at using a three-dimensional (3D hybrid finite-discrete element method (FDEM to investigate the development of an excavation damaged zone (EDZ around tunnels in a clay shale formation known as Opalinus Clay. The 3D FDEM was first calibrated against standard laboratory experiments, including Brazilian disc test and uniaxial compression test. The effect of increasing confining pressure on the mechanical response and fracture propagation of the rock was quantified under triaxial compression tests. Polyaxial (or true triaxial simulations highlighted the effect of the intermediate principal stress (σ2 on fracture directions in the model: as the intermediate principal stress increased, fractures tended to align in the direction parallel to the plane defined by the major and intermediate principal stresses. The peak strength was also shown to vary with changing σ2.

  15. Mechanical properties, mineralogical composition, and micro fabric of Opalinus Clay. Sandy and shaly facies (Mont Terri, Switzerland)

    Kaufhold, Annette; Graesle, Werner; Plischke, Ingo

    2015-01-01

    For the safe disposal of high-level radioactive waste, different host rocks are currently considered. The favorable properties of claystone are low permeability, retention capacity for some radionuclides, and the ability to self-seal cracks, e.g. by swelling or time-dependent compaction creep. For the understanding of the long-term behavior of clay host rocks, the interaction between mechanical behavior, micro fabric, and mineral composition has to be understood (Bock et al., 2010). In the international research project Mont Terri (Switzerland) the Opalinus Clay (Jurassic Formation) is investigated in an underground rock laboratory (URL). In the present study the relationship between mechanical, mineralogical and micro fabric properties were studied on representative samples of the sandy and shaly facies of the Opalinus Clay (OPA) from Mont Terri. The mineral composition of all samples was analysed by using a complex mineral phase analysis. Therefore, the results of the X-ray diffraction, X-ray fluoreszence, organic and inorganic carbonate analysis (LECO) were adjusted with each other. In the case of the sandy facies (OPA) the mechanical strength inrcreases with increasing carbonate content. Here small carbonate particles form the matrix and act as stabilisator. The carbonates of the shaly facies (OPA), on the other hand, are mainly fossil fragments (e.g. shells) aligned parallel to bedding. These large carbonate particles are acting as predetermined breaking surfaces. Hence, in the case of shaly facies (OPA) the mechanical strength decreases with increasing carbonate content. Image Analyses (Fiji registered ) of scattering electron microscope images of polished sections proved the determined microstructural differences. Besides, carbonate particles in the sandy facies are mostly isometric, in contrast carbonates of the shaly facies show different shapes. This is explained further in terms of the aspect ratio. The mechanical tests were carried out as triaxial

  16. Mechanical properties, mineralogical composition, and micro fabric of Opalinus Clay. Sandy and shaly facies (Mont Terri, Switzerland)

    Kaufhold, Annette; Graesle, Werner [BGR Hannover (Germany); Plischke, Ingo

    2015-07-01

    For the safe disposal of high-level radioactive waste, different host rocks are currently considered. The favorable properties of claystone are low permeability, retention capacity for some radionuclides, and the ability to self-seal cracks, e.g. by swelling or time-dependent compaction creep. For the understanding of the long-term behavior of clay host rocks, the interaction between mechanical behavior, micro fabric, and mineral composition has to be understood (Bock et al., 2010). In the international research project Mont Terri (Switzerland) the Opalinus Clay (Jurassic Formation) is investigated in an underground rock laboratory (URL). In the present study the relationship between mechanical, mineralogical and micro fabric properties were studied on representative samples of the sandy and shaly facies of the Opalinus Clay (OPA) from Mont Terri. The mineral composition of all samples was analysed by using a complex mineral phase analysis. Therefore, the results of the X-ray diffraction, X-ray fluoreszence, organic and inorganic carbonate analysis (LECO) were adjusted with each other. In the case of the sandy facies (OPA) the mechanical strength inrcreases with increasing carbonate content. Here small carbonate particles form the matrix and act as stabilisator. The carbonates of the shaly facies (OPA), on the other hand, are mainly fossil fragments (e.g. shells) aligned parallel to bedding. These large carbonate particles are acting as predetermined breaking surfaces. Hence, in the case of shaly facies (OPA) the mechanical strength decreases with increasing carbonate content. Image Analyses (Fiji {sup registered}) of scattering electron microscope images of polished sections proved the determined microstructural differences. Besides, carbonate particles in the sandy facies are mostly isometric, in contrast carbonates of the shaly facies show different shapes. This is explained further in terms of the aspect ratio. The mechanical tests were carried out as triaxial

  17. The safety case for a HLW repository in Opalinus clay: aims, methodology, first results

    Zuidema, Piet

    2002-01-01

    Piet Zuidema (Nagra, Switzerland) described the development of the safety case for a high level waste repository in Opalinus clay in which canisters would be placed in large vaults. The current phase of work was concerned with demonstrating the feasibility of the disposal concept. The Safety Case is taken to mean a set of arguments to support a statement that the proposed facility will meet relevant safety criteria and will include arguments giving the basis for confidence that those arguments are correct and properly taking account of uncertainties. The safety strategy was concerned both with the inherent robustness of the disposal concept and the adequacy of the assessment capability. As regards the former, the arguments being advanced were primarily qualitative. Key issues in terms of the documentation of the Safety Case were traceability and transparency of information, including how to ensure that key arguments did not become obscured because of the need to make available very large quantities of information

  18. Performance of the Opalinus Clay under thermal loading: experimental results from Mont Terri rock laboratory (Switzerland)

    Gens, A. [Universitat Politència de Catalunya, Barcelona (Spain); Wieczorek, K. [Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) GmbH, Braunschweig (Germany); Gaus, I. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); and others

    2017-04-15

    The paper presents an overview of the behaviour of Opalinus Clay under thermal loading as observed in three in situ heating tests performed in the Mont Terri rock laboratory: HE-B, HE-D and HE-E. The three tests are summarily described; they encompass a broad range of test layouts and experimental conditions. Afterwards, the following topics are examined: determination of thermal conductivity, thermally-induced pore pressure generation and thermally-induced mechanical effects. The mechanisms underlying pore pressure generation and dissipation are discussed in detail and the relationship between rock damage and thermal loading is examined using an additional in situ test: SE-H. The paper concludes with an evaluation of the various thermo-hydro-mechanical (THM) interactions identified in the heating tests. (authors)

  19. The opalinus clay project - disposal of medium and highly-active nuclear wastes

    Mueller, U.

    2003-01-01

    This article describes the project to demonstrate the feasibility of disposing of long-living medium-active and highly-radioactive nuclear wastes in sedimentary rock in Switzerland. The disposal tasks to be carried out are reviewed and the solutions proposed are described, including short-term handling, intermediate storage and final disposal of low, medium and highly-active wastes. The present state of affairs is described and, in particular, the feasibility of implementing a final storage facility in the opalinus clay beds to be found in northern Switzerland. The project for such a facility in the wine-growing area of the canton of Zurich is described in detail, including the storage concept, the technology to be used and operational aspects as well as questions of safety

  20. Excavation Induced Hydraulic Response of Opalinus Clay - Investigations of the FE-Experiment at the Mont Terri URL in Switzerland

    Vogt, T.; Müller, H. R.; Garitte, B.; Sakaki, T.; Vietor, T.

    2013-12-01

    The Full-Scale Emplacement (FE) Experiment at the Mont Terri underground research laboratory in Switzerland is a full-scale heater test in a clay-rich formation (Opalinus Clay). Based on the Swiss disposal concept it simulates the construction, emplacement, backfilling, and post-closure thermo-hydro-mechanical (THM) evolution of a spent fuel / vitrified high-level waste (SF / HLW) repository tunnel in a realistic manner. The main aim of this experiment is to investigate SF / HLW repository-induced THM coupled effects mainly in the host rock but also in the engineered barrier system (EBS), which consists of bentonite pellets and blocks. A further aim is to gather experience with full-scale tunnel construction and associated hydro-mechanical (HM) processes in the host rock. The entire experiment implementation (in a 50 m long gallery with approx. 3 m diameter) as well as the post-closure THM evolution will be monitored using a network of several hundred sensors (state-of-the-art sensors and measurement systems as well as fiber-optic sensors). The sensors are distributed in the host rock's near- and far-field, the tunnel lining, the EBS, and on the heaters. The heater emplacement and backfilling has not started yet, therefore only the host rock instrumentation is installed at the moment and is currently generating data. We will present the instrumentation concept and rationale as well as the first monitoring results of the excavation and ventilation phase. In particular, we investigated the excavation induced hydraulic response of the host rock. Therefore, the spatiotemporal evolution of porewater-pressure time series was analyzed to get a better understanding of HM coupled processes during and after the excavation phase as well as the impact of anisotropic geomechanic and hydraulic properties of the clay-rich formation on its hydraulic behavior. Excavation related investigations were completed by means of inclinometer data to characterize the non-elastic and time

  1. Litho- and biostratigraphy of the Opalinus Clay and bounding formations in the Mont Terri rock laboratory (Switzerland)

    Hostettler, B.; Reisdorf, A. G.; Jaeggi, D.

    2017-01-01

    A 250 m-deep inclined well, the Mont Terri BDB-1, was drilled through the Jurassic Opalinus Clay and its bounding formations at the Mont Terri rock laboratory (NW Switzerland). For the first time, a continuous section from (oldest to youngest) the topmost members of the Staffelegg Formation to the basal layers of the Hauptrogenstein Formation is now available in the Mont Terri area. We extensively studied the drill core for lithostratigraphy and biostratigraphy, drawing upon three sections from the Mont Terri area. The macropaleontological, micropaleontological, and palynostratigraphical data are complementary, not only spatially but they also cover almost all biozones from the Late Toarcian to the Early Bajocian. We ran a suite of geophysical logs to determine formational and intraformational boundaries based on clay content in the BDB-1 well. In the framework of an interdisciplinary study, analysis of the above-mentioned formations permitted us to process and derive new and substantial data for the Mont Terri area in a straightforward way. Some parts of the lithologic inventory, stratigraphic architecture, thickness variations, and biostratigraphic classification of the studied formations deviate considerably from occurrences in northern Switzerland that crop out further to the east. For instance, with the exception of the Sissach Member, no further lithostratigraphic subdivision in members is proposed for the Passwang Formation. Also noteworthy is that the ca. 130 m-thick Opalinus Clay in the BDB-1 core is 20 m thinner than that equivalent section found in the Mont Terri tunnel. The lowermost 38 m of the Opalinus Clay can be attributed chronostratigraphically solely to the Aalensis Zone (Late Toarcian). Deposition of the Opalinus Clay began at the same time farther east in northern Switzerland (Aalensis Subzone, Aalensis Zone), but in the Mont Terri area the sedimentation rate was two or three orders of magnitude higher. (authors)

  2. Litho- and biostratigraphy of the Opalinus Clay and bounding formations in the Mont Terri rock laboratory (Switzerland)

    Hostettler, B. [Naturhistorisches Museum der Burgergemeinde Berne, Berne (Switzerland); Reisdorf, A. G. [Geologisch-Paläontologisches InstitutUniversität Basle, Basle (Switzerland); Jaeggi, D. [Swisstopo, Federal Office of Topography, Wabern (Switzerland); and others

    2017-04-15

    A 250 m-deep inclined well, the Mont Terri BDB-1, was drilled through the Jurassic Opalinus Clay and its bounding formations at the Mont Terri rock laboratory (NW Switzerland). For the first time, a continuous section from (oldest to youngest) the topmost members of the Staffelegg Formation to the basal layers of the Hauptrogenstein Formation is now available in the Mont Terri area. We extensively studied the drill core for lithostratigraphy and biostratigraphy, drawing upon three sections from the Mont Terri area. The macropaleontological, micropaleontological, and palynostratigraphical data are complementary, not only spatially but they also cover almost all biozones from the Late Toarcian to the Early Bajocian. We ran a suite of geophysical logs to determine formational and intraformational boundaries based on clay content in the BDB-1 well. In the framework of an interdisciplinary study, analysis of the above-mentioned formations permitted us to process and derive new and substantial data for the Mont Terri area in a straightforward way. Some parts of the lithologic inventory, stratigraphic architecture, thickness variations, and biostratigraphic classification of the studied formations deviate considerably from occurrences in northern Switzerland that crop out further to the east. For instance, with the exception of the Sissach Member, no further lithostratigraphic subdivision in members is proposed for the Passwang Formation. Also noteworthy is that the ca. 130 m-thick Opalinus Clay in the BDB-1 core is 20 m thinner than that equivalent section found in the Mont Terri tunnel. The lowermost 38 m of the Opalinus Clay can be attributed chronostratigraphically solely to the Aalensis Zone (Late Toarcian). Deposition of the Opalinus Clay began at the same time farther east in northern Switzerland (Aalensis Subzone, Aalensis Zone), but in the Mont Terri area the sedimentation rate was two or three orders of magnitude higher. (authors)

  3. Geochemical signature of paleofluids in microstructures from Main Fault in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

    Clauer, N. [Laboratoire d’Hydrologie et de Géochimie de Strasbourg (CNRS-UdS), Strasbourg (France); Techer, I. [Equipe Associée, Chrome, Université de Nîmes, Nîmes (France); Nussbaum, Ch. [Swiss Geological Survey, Federal Office of Topography Swisstopo, Wabern (Switzerland); Laurich, B. [Structural Geology, Tectonics and Geomechanics, RWTH Aachen University, Aachen (Germany); Laurich, B. [Federal Institute for Geosciences and Natural Resources BGR, Hannover (Germany)

    2017-04-15

    The present study reports on elemental and Sr isotopic analyses of calcite and associated celestite infillings of various microtectonic features collected mostly in the Main Fault of the Opalinus Clay from Mont Terri rock laboratory. Based on a detailed microstructural description of veins, slickensides, scaly clay aggregates and gouges, the geochemical signatures of the infillings were compared to those of the leachates from undeformed Opalinus Clay, and to the calcite from veins crosscutting Hauptrogenstein, Passwang and Staffelegg Formations above and below the Opalinus Clay. Vein calcite and celestite from Main Fault yield identical {sup 87}Sr/{sup 86}Sr ratios that are also close to those recorded in the Opalinus Clay matrix inside the Main Fault, but different from those of the diffuse Opalinus Clay calcite outside the fault. These varied {sup 87}Sr/{sup 86}Sr ratios of the diffuse calcite evidence a lack of interaction among the associated connate waters and the flowing fluids characterized by a homogeneous Sr signature. The {sup 87}Sr/{sup 86}Sr homogeneity at 0.70774 ± 0.00001 (2σ) for the infillings of most microstructures in the Main Fault, as well as of veins from nearby limestone layer and sediments around the Opalinus Clay, claims for an 'infinite' homogeneous marine supply, whereas the gouge infillings apparently interacted with a fluid chemically more complex. According to the known regional paleogeographic evolution, two seawater supplies were inferred and documented in the Delémont Basin: either during the Priabonian (38-34 Ma ago) from western Bresse graben, and/or during the Rupelian (34-28 Ma ago) from northern Rhine Graben. The Rupelian seawater that yields a mean {sup 87}Sr/{sup 86}Sr signature significantly higher than those of the microstructural infillings seems not to be the appropriate source. Alternatively, Priabonian seawater yields a mean {sup 87}Sr/{sup 86}Sr ratio precisely matching that of the leachates from diffuse

  4. Monitoring water content in Opalinus Clay within the FE-Experiment: Test application of dielectric water content sensors

    Sakaki, T.; Vogt, T.; Komatsu, M.; Müller, H. R.

    2013-12-01

    The spatiotemporal variation of water content in the near field rock around repository tunnels for radioactive waste in clay formations is one of the essential quantities to be monitored for safety assessment in many waste disposal programs. Reliable measurements of water content are important not only for the understanding and prediction of coupled hydraulic-mechanic processes that occur during tunnel construction and ventilation phase, but also for the understanding of coupled thermal-hydraulic-mechanical (THM) processes that take place in the host rock during the post closure phase of a repository tunnel for spent fuel and high level radioactive waste (SF/HLW). The host rock of the Swiss disposal concept for SF/HLW is the Opalinus Clay formation (age of approx. 175 Million years). To better understand the THM effects in a full-scale heater-engineered barrier-rock system in Opalinus Clay, a full-scale heater test, namely the Full-Scale Emplacement (FE) experiment, was initiated in 2010 at the Mont Terri underground rock laboratory in north-western Switzerland. The experiment is designed to simulate the THM evolution of a SF/HLW repository tunnel based on the Swiss disposal concept in a realistic manner during the construction, emplacement, backfilling, and post-closure phases. The entire experiment implementation (in a 50 m long gallery with approx. 3 m diameter) as well as the post-closure THM evolution will be monitored using a network of several hundred sensors. The sensors will be distributed in the host rock, the tunnel lining, the engineered barrier, which consists of bentonite pellets and blocks, and on the heaters. The excavation is completed and the tunnel is currently being ventilated. Measuring water content in partially saturated clay-rich high-salinity rock with a deformable grain skeleton is challenging. Therefore, we use the ventilation phase (before backfilling and heating) to examine the applicability of commercial water content sensors and to

  5. Effects of post-disposal gas generation in a repository for spent fuel, high-level waste and long-lived intermediate level waste sited in opalinus clay

    Johnson, L.; Marschall, P.; Zuidema, P.; Gribi, P.

    2004-07-01

    This comprehensive report issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at post-disposal gas generation in a repository for spent fuel and highly radioactive wastes in Opalinus clay strata. This study provides a comprehensive treatment of the issue of gas generation in a repository for spent fuel (SF), vitrified high-level waste (HLW) and long-lived intermediate-level waste (ILW), sited in the Opalinus clay of the Zuercher Weinland in northern Switzerland. The issue of how gas generation in and transport from waste repositories may influence disposal system performance has been under study for many years, both at Nagra and internationally. The report consists of three main parts: (i) A synthesis of basic information on the host rock and on details of repository construction; (ii) A discussion on gas transport characteristics of the engineered barrier system and the geosphere; (iii) A discussion on the effects of gas on system performance, based on the available information on gas generation, gas transport properties and gas pathways provided in the previous parts of the report. Simplified model calculations based on a mass balance approach for the gas generated within the repository are presented and discussed

  6. Multistep triaxial strength tests: investigating strength parameters and pore pressure effects on Opalinus Clay

    Graesle, W.

    2010-01-01

    Document available in extended abstract form only. The impact of natural variability between rock samples from a single formation is a common problem for the characterisation of THM properties of rocks. Data variation arising from heterogeneity between samples often obscures details of material behaviour. Besides efforts to reduce this statistical noise by careful selection of samples, there are essentially two approaches to overcome this problem: - To generate very large data sets for better statistics. - To avoid the impact of natural variability by yielding an extensive data set from a single sample. The multistep strength test follows the latter approach to characterise the mechanical behaviour of Opalinus Clay from Mont Terri and the possible impact of pore pressure effects. The concept of the multistep strength test comprises three test sections, each focused on the investigation of one mechanical characteristic of Opalinus Clay. Any section is composed of a series of strain controlled load cycles at various levels of confining pressure. 1) The linear elastic limit, i.e. the onset of nonlinearity in the stress-strain-relationship σ dev (ε 1 ) during strain-controlled triaxial loading, is determined in section 1. It defines a lower limit for the onset of damage. Avoiding sample damage is essential during this test section to ensure that all measurements reflect the behaviour of undisturbed material. Therefore, a rather strict and well detectable criterion for the onset of nonlinearity is required to enable a timely termination of any load phase. 2) Section 2 is focused on shear strength. Any load cycle is stopped as soon as peak stress is detected. As progressive damage of the sample is unavoidable during this process, it must be expected that only very few measured peak stresses approximately represent properties of the undamaged material. 3) Test section 3 is a conventional test of residual strength. Tests are carried out on cylindrical samples (100 mm

  7. Natural gas extraction and artificial gas injection experiments in Opalinus Clay, Mont Terri rock laboratory (Switzerland)

    Vinsot, A.; Lundy, M. [Agence Nationale pour la Gestion des Déchets Radioactifs ANDRA, Meuse Haute-Marne Center, Bure (France); Appelo, C.A.J. [Dr C.A.J. Appelo, Hydrochemical Consultant, Amsterdam (Netherlands); and others

    2017-04-15

    Two experiments have been installed at Mont Terri in 2004 and 2009 that allowed gas circulation within a borehole at a pressure between 1 and 2 bar. These experiments made it possible to observe the natural gases that were initially dissolved in pore-water degassing into the borehole and to monitor their content evolution in the borehole over several years. They also allowed for inert (He, Ne) and reactive (H{sub 2}) gases to be injected into the borehole with the aim either to determine their diffusion properties into the rock pore-water or to evaluate their removal reaction kinetics. The natural gases identified were CO{sub 2}, light alkanes, He, and more importantly N{sub 2}. The natural concentration of four gases in Opalinus Clay pore-water was evaluated at the experiment location: N{sub 2} 2.2 mmol/L ± 25%, CH{sub 4} 0.30 mmol/L ± 25%, C{sub 2}H{sub 6} 0.023 mmol/L ± 25%, C{sub 3}H{sub 8} 0.012 mmol/L ± 25%. Retention properties of methane, ethane, and propane were estimated. Ne injection tests helped to characterize rock diffusion properties regarding the dissolved inert gases. These experimental results are highly relevant towards evaluating how the fluid composition could possibly evolve in the drifts of a radioactive waste disposal facility. (authors)

  8. Sorption of neptunium(V) on opalinus clay under aerobic/anaerobic conditions

    Froehlich, D.R.; Amayri, S.; Drebert, J.; Reich, T.

    2011-01-01

    The interaction between neptunium(V) and a natural argillaceous rock (Opalinus Clay (OPA), Mont Terri, Switzerland) has been investigated in batch sorption experiments by varying pH (6-10), Np(V) concentration (10 -12 -10 -4 M), solid-to-liquid ratio (2-20 g/L), and partial pressure of CO 2 (10 -3.5 and 10 -2.3 atm) under aerobic/anaerobic conditions in saturated calcite solution. All batch experiments were carried out using well characterized aerobic and anaerobic dry powders of OPA. The results show a great influence of pH on Np(V) sorption. Under aerobic conditions sorption increases with increasing pH until maximum sorption is reached between pH 8-9. At pH > 9 sorption decreases due to the formation of negatively charged Np(V)-carbonate complexes. By increasing p CO 2 from 10 -3.5 to 10 -2.3 atm, the sorption edge is shifted ∼ 0.5 units to lower pH values. Under anaerobic conditions stronger sorption of 8 x 10 -6 M Np(V) was found, possibly due to partial reduction of Np(V) to Np(IV). The sorption of 8 x 10 -6 M Np(V) under aerobic conditions at pH 8.2 in saturated calcite solution increases continuously with increasing solid-to-liquid ratio of OPA in the range of 2-20 g/L with a constant K d value of 126 ± 13 L/kg. The sorption isotherm was measured over seven orders of magnitude in Np(V) concentration using 239 Np as tracer. The sorption isotherm could be divided in a part of linear sorption behaviour between 10 -13 -10 -9 M Np(V) and non-linear behaviour in the range of 10 -9 -10 -4 M Np(V). (orig.)

  9. Concrete - Opalinus clay interaction: in-situ experiment and technique for coring undisturbed interfaces

    Maeder, U.; Dolder, F.; Jenni, A.; Schwyn, B.; Frieg, B.; Eul, A.

    2012-01-01

    Document available in extended abstract form only. Designs for deep geologic disposal of radioactive waste foresee cementitious materials as structural elements, backfill or waste matrix. Interactions near interfaces are driven by chemical gradients in pore water and resultant diffusive transport, and are predicted to lead to mineralogical alterations in the barrier system, which in turn influences properties like swelling pressure, permeability, or specific retention in case of clay materials. Reactive transport modelling predictions and laboratory and in situ studies revealed significant alteration in both cement and clay-stone. An increase in porosity in the cement close to the interface, and clogging in the clay-stone adjacent to the interface is commonly predicted and observed. The Cement-Clay Interaction (CI) Experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) aims at demonstrating some of the processes at interfaces to be expected at a realistic spatial scale and under saturated conditions. A duration of 20 years is foreseen during which reaction progress should become measurable and thus comparable to laboratory experiments and modelling predictions. Companion studies address cement hydration, and develop new high-resolution techniques for phase identification using μ-X-ray diffraction at the Paul Scherrer Institut. The field experiment at Mont Terri comprises two vertical boreholes (384 mm diameter, up to 9 m length) in Opalinus Clay (OPA) filled with layers of three different concretes and bentonite. The concrete formulations are based on three different binders: Portland cement (OPC), ESDRED cement designed for repository applications (40% of cement substituted by silica fume), and low alkali cement (LAC, containing slag and nano-silica). The characterisation of the three concrete-OPA interfaces after 2 years of alteration are presented in a companion contribution (Jenni et al.). A key issue is the repeat recovery of

  10. Mont Terri Project - Engineered barrier emplacement experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C.; Garcia-Sineriz, J.; Alonso, E.; Alheid, H.-J.; Bluemling, P.

    2007-01-01

    The Engineered Barrier (EB) experiment was a full-scale test for the demonstration, in a horizontal drift, of an emplacement technics of the clay barrier, using a granular bentonite material in the upper part of this barrier and bentonite blocks at the bottom. The test has been carried out in a 6 m long section of a niche excavated in Opalinus Clay of the Mont Terri underground laboratory. A steel dummy canister, with the same dimensions and weight as the real reference canisters, was placed on top of a bed of highly compacted bentonite blocks (in turn lying on a concrete bed), and the rest of the clay barrier volume was backfilled with a Granular Bentonite Material (GBM), made of very highly compacted pellets of different sizes. Hydro-mechanical instrumentation and an artificial hydration system (to accelerate the saturation of the clay barrier) were installed, and the test section sealed with a concrete plug. The evolution of the hydro-mechanical parameters along the hydration, both in the barrier and in the clayey rock formation, has been monitored during about 1.5 years, and modelled using the CODE-BRIGHT code. The EB experiment has proved that fully automated production of a Granular Bentonite Material (GBM) is possible and large quantities can be produced in due time in the required quality. Only minor modifications of existing production lines in industry for other applications were necessary to achieve this result. In the EB test section, a dry density of 1.36 g/cm 3 of the emplaced GBM has been obtained. With this value it is estimated that the hydraulic conductivity of this material is lower than 5 x 10 -12 m/s and the swelling pressure is about 1.3 MPa. Even though the EB test section conditions are now not considered as representative of a true demonstration, it is deemed that the model emplacement testing results (dry density of about 1.40 g/cm 3 ) serve well to demonstrate the achievable densities expected in the real world setting. The artificial

  11. Mont Terri Project - Engineered barrier emplacement experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C. [Empresa Nacional de Residuos Radioactivos SA (ENRESA), Madrid (Spain); Garcia-Sineriz, J. [Asociacion para la Investigacion y Desarollo Industrial de los Recursos Naturales (AITEMIN), Madrid (Spain); Alonso, E. [Centre Internacional de Metodos Numerics en Ingenyeria (CIMNE), Barcelona (Spain); Alheid, H.-J. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Bluemling, P. [National Cooperative for the Disposal of Radioactive Waste (Nagra), Wettingen (Switzerland)

    2007-07-01

    The Engineered Barrier (EB) experiment was a full-scale test for the demonstration, in a horizontal drift, of an emplacement technics of the clay barrier, using a granular bentonite material in the upper part of this barrier and bentonite blocks at the bottom. The test has been carried out in a 6 m long section of a niche excavated in Opalinus Clay of the Mont Terri underground laboratory. A steel dummy canister, with the same dimensions and weight as the real reference canisters, was placed on top of a bed of highly compacted bentonite blocks (in turn lying on a concrete bed), and the rest of the clay barrier volume was backfilled with a Granular Bentonite Material (GBM), made of very highly compacted pellets of different sizes. Hydro-mechanical instrumentation and an artificial hydration system (to accelerate the saturation of the clay barrier) were installed, and the test section sealed with a concrete plug. The evolution of the hydro-mechanical parameters along the hydration, both in the barrier and in the clayey rock formation, has been monitored during about 1.5 years, and modelled using the CODE-BRIGHT code. The EB experiment has proved that fully automated production of a Granular Bentonite Material (GBM) is possible and large quantities can be produced in due time in the required quality. Only minor modifications of existing production lines in industry for other applications were necessary to achieve this result. In the EB test section, a dry density of 1.36 g/cm{sup 3} of the emplaced GBM has been obtained. With this value it is estimated that the hydraulic conductivity of this material is lower than 5 x 10{sup -12} m/s and the swelling pressure is about 1.3 MPa. Even though the EB test section conditions are now not considered as representative of a true demonstration, it is deemed that the model emplacement testing results (dry density of about 1.40 g/cm{sup 3}) serve well to demonstrate the achievable densities expected in the real world setting. The

  12. Heater test in the Opalinus Clay of the Mont Terri URL. Gas release and water redistribution - Contribution to heater experiment (HE); Rock and bentonite thermo-hydro-mechanical (THM) processes in the nearfield

    Jockwer, N.; Wieczorek, K.

    2006-06-01

    Beside salt and granite, clay formations are investigated as potential host rocks for disposing radioactive waste. In Switzerland in the canton Jura close to the city of St. Ursanne, an underground laboratory was built in the vicinity of the reconnaissance gallery of a motorway tunnel. Since 1995, a consortium of 12 international organisations is running this laboratory for investigating the suitability of the Opalinus clay formation with regard to disposal of radioactive waste. In 1999, the Heater Experiment B (HE-B) was started for investigating the coupled thermo-hydro-mechanical (THM) processes of the Opalinus clay in interaction with the bentonite buffer. The principal contractors of this project were the Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), the Empresa Nacional de Residuos Radiactivos S. A. (ENRESA), the Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, and the National Cooperative for the Disposal of Radioactive Waste (NAGRA). GRS participated in that experiment for determining the subjects of gas generation, gas release, water content, and water redistribution in the Opalinus clay during heating. This was achieved by analysing gas and water samples from the test field before, during, and after the heating period and by performing geoelectric tomography measurements in the heated region. The in-situ measurements were supported by an additional laboratory programme. This report deals with the work of GRS performed in this project during the years 1999 to 2005. All the results obtained in the frame of the project are presented. Additional laboratory measurements conducted by the Pore Water Laboratory at CIEMAT in Madrid are also presented. The participation of GRS was funded by German Ministry of Economics and Labour (BMWA) under the contract No. 02 E 9602 and by the Commission of the European Communities under the contract No. FIKW.CT-2001-00132. (orig.)

  13. Ageing effect on deep-buried argillites stored after coring: study cases of Opalinus Clays and Callovo-Oxfordian argillites

    Techer, I.; Clauer, N.; Liewig, N.

    2010-01-01

    Document available in extended abstract form only. A petrophysical and geochemical study of deep-seated sediments requires either shaft excavation for in situ investigations or core drilling and storage for laboratory measurements and observations. In both cases, measured and observed data should be as representative as possible of the intrinsic characteristics of the rocks before human interference, which is especially critical for potential host-rocks of deep nuclear-waste storage. Almost instantaneous alteration processes were described due to interactions with the atmosphere by supply of O 2 , CO 2 , and water in some cases. Chemical exchanges and reactions were reported in conditioned and stored samples, despite all the care taken for treatment. The imprint of such processes remains to be very limited and therefore difficult to identify, especially by routine analyses. To provide further information about these limited modifications and to discuss the evolution of the geochemical records in deep clayed rocks when exposed to atmosphere, a coupled mineralogical and geochemical study was performed on two argillaceous rocks: the Opalinus Clays collected in the Mont-Terri URL (Switzerland) and the Callovo-Oxfordian Clays sampled in the Bure URL (France). A ∼8-m long core was drilled perpendicular to an experimental niche or gallery in each underground laboratory. Several core sections were selected as a function of distance to the wall of the niche/gallery and were analyzed repetitively relative to storage time. The samples were stored in Al-bags under vacuum, or not, and at ambient temperature or subjected to temperatures of 95 deg. C and 150 deg. C over varied periods of time, in order to enhance the reactions. The objective was the evaluation of the storage effect on the chemical and Sr isotopic compositions by leaching the rock powders with dilute acetic acid and analyzing the leachates for elemental and 87 Sr/ 86 Sr compositions. The study was complemented

  14. Coupled thermo-hydro-mechanical processes around a bentonite buffer embedded in Opalinus Clay - Comparison between measurements and calculations

    Goebel, Ingeborg; Alheid, Hans-Joachim [BGR Hannover, Stilleweg 2, D-30655 Hannover (Germany); Jockwer, Norbert [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Theodor-Heuss-Str. 4, 38122 Braunschweig (Germany); Mayor, Juan Carlos [ENRESA, Emilio Vargas 7, E-Madrid (Spain); Garcia-Sineriz, Jose Luis [AITEMIN, c/ Alenza, 1 - 28003 Madrid (Spain); Alonso, Eduardo; Munoz, Juan Jorge [International Center for Numerical Methods in Engineering, CIMNE, Edificio C-1, Campus Norte UPC, C/Gran Capitan, s/n, 08034 Barcelona (Spain); Weber, Hans Peter [NAGRA, Hardstrasse 73, CH-5430 Wettingen (Switzerland); Ploetze, Michael [ETHZ, Eidgenoessische Technische Hochschule Zuerich, ETH Zentrum, HG Raemistrasse 101, CH-8092 Zuerich (Switzerland); Klubertanz, Georg [COLENCO Power Engineering Ltd, CPE, Taefern Str. 26, 5405 Baden-Daettwil (Switzerland); Ammon, Christian [Rothpletz, Lienhard, Cie AG, Schifflaendestrasse 35, 5001 Aarau (Switzerland)

    2004-07-01

    The Heater Experiment at the Mont Terri Underground Laboratory consists of an engineered barrier system composed of compacted bentonite blocks around a heater. The bentonite barrier is embedded in Opalinus Clay. The aim of the project is improved understanding of thermo-hydro mechanically (THM) coupled processes. Calculations are performed by 2 Finite-Element programs, CODE-BRIGHT and MHERLIN, the former for the near-field modeling and the latter for the rock modeling. Numerical modeling is carried out during all phases of the project to give input for design tasks such as cooling and dismantling, and to finally produce verified models of the THM coupled engineered barrier system. Results of both programs are discussed in the light of the experimental findings. (authors)

  15. Microbial investigations in Opalinus clay from Mont Terri and in Callovo-Oxfordian argillite from Meuse/Haute-Marne

    Poulain, S.

    2006-12-01

    The subject of this Ph.D. thesis deals with research achieved in the context of the Axis 2 of the law Bataille voted on December 30, 1991 about the possibility of building a deep geological repository for medium or high activity and long living nuclear waste. Nearby such a site, some microorganisms may influence the mobility of radionuclides coming from the waste canisters. This work consisted in looking for autochthonous microorganisms in the Opalinus clay formation from Mont Terri (Switzerland) and in the Callovo-Oxfordian argillite from Meuse/Haute-Marne (France). Microbial Investigations in these unknown unperturbed environments suggested very low microbial densities in the clayey sediments. However, new bacterial species could be isolated from those samples. In addition, a part of the allochthonous population, which has been introduced by air and human activity, could be identified in the Meuse/Haute-Marne underground research laboratory. (author)

  16. Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

    Laurich, Ben; Urai, Janos L.; Vollmer, Christian; Nussbaum, Christophe

    2018-01-01

    We studied gouge from an upper-crustal, low-offset reverse fault in slightly overconsolidated claystone in the Mont Terri rock laboratory (Switzerland). The laboratory is designed to evaluate the suitability of the Opalinus Clay formation (OPA) to host a repository for radioactive waste. The gouge occurs in thin bands and lenses in the fault zone; it is darker in color and less fissile than the surrounding rock. It shows a matrix-based, P-foliated microfabric bordered and truncated by micrometer-thin shear zones consisting of aligned clay grains, as shown with broad-ion-beam scanning electron microscopy (BIB-SEM) and optical microscopy. Selected area electron diffraction based on transmission electron microscopy (TEM) shows evidence for randomly oriented nanometer-sized clay particles in the gouge matrix, surrounding larger elongated phyllosilicates with a strict P foliation. For the first time for the OPA, we report the occurrence of amorphous SiO2 grains within the gouge. Gouge has lower SEM-visible porosity and almost no calcite grains compared to the undeformed OPA. We present two hypotheses to explain the origin of gouge in the Main Fault: (i) authigenic generation consisting of fluid-mediated removal of calcite from the deforming OPA during shearing and (ii) clay smear consisting of mechanical smearing of calcite-poor (yet to be identified) source layers into the fault zone. Based on our data we prefer the first or a combination of both, but more work is needed to resolve this. Microstructures indicate a range of deformation mechanisms including solution-precipitation processes and a gouge that is weaker than the OPA because of the lower fraction of hard grains. For gouge, we infer a more rate-dependent frictional rheology than suggested from laboratory experiments on the undeformed OPA.

  17. Mont Terri Project - Ventilation experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C. [Empresa Nacional de Residuos Radioactivos SA (ENRESA), Madrid (Spain); Garcia-Sineriz, J. [Asociacion para la Investigacion y Desarollo Industrial de los Recursos Naturales (AITEMIN), Madrid (Spain); Velasco, M. [DM Iberia SA, Madrid (Spain); Gomez-Hernandez, J. [Ingenieria Hidraulica y Medio Ambiente, Escuela de Ingenieros de Caminos (UPV), Valencia (Spain); Lloret, A.; Matray, J.-M. [IRSN/DEI/SARG/LETS, Fontenay-aux-Roses (France); Coste, F. [Aradis ESG, Sevres Cedex (France); Giraud, A. [LAEGO-ENSG, Vandoeuvre les Nancy (France); Rothfuchs, T. [Gesellschaft fuer Anlagen und Reaktorsicherheit mbH (GRS), Braunschweig (Germany); Marschall, P. [National Cooperative for the Disposal of Radioactive Waste (Nagra), Wettingen (Switzerland); Roesli, U. [Solexperts AG, Moenchaltorf (Switzerland); Mayer, G. [Colenco Power Engineering Ltd, Baden (Switzerland)

    2007-07-01

    The ventilation of the underground drifts during the construction and operation of a radioactive waste repository could produce the partial desaturation of the rock around the drifts, modifying its thermo-hydro-mechanical properties, especially in clayey rocks. This change of rock properties may have an impact on the design of the repositories (drifts spacing and repository size), which depends on the thermal load that the clay barrier and the rock can accept. To evaluate 'in situ' and better understand the desaturation process of a hard clay formation, the Ventilation Experiment (VE) has been carried out at the Mont Terri underground laboratory (Switzerland), generating a flow of dry air during several months along a section of a microtunnel. Specifically, the VE test has been performed, under practically isothermal conditions (T {approx_equal} 15-16 {sup o}C), in a 10 m long section of a non-lined horizontal microtunnel (diameter = 1.3 m), excavated in 1999 in the shaly facies of the Opalinus Clay of Mont Terri. The microtunnel is oriented perpendicular to the bedding strike direction of the rock (mean value of the bedding dip {approx_equal} 25{sup o}). The VE experiment real data and its modelling have shown that the desaturation of clayey rocks of low hydraulic conductivity (K < 10{sup -12} m/s) due to ventilation is very small. Under real repository conditions, the thermal and hydro-mechanical rock characteristics will not be practically affected by the ventilation. Specifically, the monitoring of the VE test (mainly the hygrometer data, confirmed also by the geoelectrical measurements) indicates that, after about 5 months of ventilation with almost dry air, the rock relative humidity (and then the degree of saturation) was less than 95% only in a ring of thickness less than 40 cm. Nevertheless, a suction state (subatmospheric liquid pressures) developed up to a distance of about 2 m, but it should be kept in mind that a clayey rock such as the

  18. Mont Terri Project - Ventilation experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C.; Garcia-Sineriz, J.; Velasco, M.; Gomez-Hernandez, J.; Lloret, A.; Matray, J.-M.; Coste, F.; Giraud, A.; Rothfuchs, T.; Marschall, P.; Roesli, U.; Mayer, G.

    2007-01-01

    The ventilation of the underground drifts during the construction and operation of a radioactive waste repository could produce the partial desaturation of the rock around the drifts, modifying its thermo-hydro-mechanical properties, especially in clayey rocks. This change of rock properties may have an impact on the design of the repositories (drifts spacing and repository size), which depends on the thermal load that the clay barrier and the rock can accept. To evaluate 'in situ' and better understand the desaturation process of a hard clay formation, the Ventilation Experiment (VE) has been carried out at the Mont Terri underground laboratory (Switzerland), generating a flow of dry air during several months along a section of a microtunnel. Specifically, the VE test has been performed, under practically isothermal conditions (T ≅ 15-16 o C), in a 10 m long section of a non-lined horizontal microtunnel (diameter = 1.3 m), excavated in 1999 in the shaly facies of the Opalinus Clay of Mont Terri. The microtunnel is oriented perpendicular to the bedding strike direction of the rock (mean value of the bedding dip ≅ 25 o ). The VE experiment real data and its modelling have shown that the desaturation of clayey rocks of low hydraulic conductivity (K -12 m/s) due to ventilation is very small. Under real repository conditions, the thermal and hydro-mechanical rock characteristics will not be practically affected by the ventilation. Specifically, the monitoring of the VE test (mainly the hygrometer data, confirmed also by the geoelectrical measurements) indicates that, after about 5 months of ventilation with almost dry air, the rock relative humidity (and then the degree of saturation) was less than 95% only in a ring of thickness less than 40 cm. Nevertheless, a suction state (subatmospheric liquid pressures) developed up to a distance of about 2 m, but it should be kept in mind that a clayey rock such as the Opalinus Clay is quasi-saturated for suction values up

  19. Project Opalinus clay Zuercher Weinland of Nagra. Evaluation of the geo-scientific data base and of the construction engineering aspects

    2005-02-01

    In this report the Commission for Nuclear Waste Management (KNE) assesses the geological and engineering aspects of the project Opalinus Clay, in which Nagra demonstrates the postclosure safety of geological disposal of spent fuel (SF), vitrified high-level wastes (HLW) and intermediate-level wastes (ILW) in a repository in the Opalinus Clay of the Zuercher Weinland in northern Switzerland. After in-depth examination of the geological database, KNE concludes that the demonstration of a suitable geological site for final disposal of SF, HLW and ILW in the Opalinus Clay of the Zuercher Weinland has been achieved. The geological assumptions Nagra uses for the assessment of long-term safety are based on data that have been carefully collected and interpreted. KNE acknowledges that Nagra interpreted the geological data correctly and adequately using state-of-the-art techniques. In case of lacking information, Nagra has used conservative or worst-case assumptions. The information documented by Nagra represents a good synthesis of field, laboratory and literature data. The tectonic situation of the Zuercher Weinland was examined in great details by Nagra. In the centre of the investigated region, where the Opalinus Clay occurs at 600 to 750 meters depth, the 3D-seismic data confirm its undisturbed stratification in an area of about 15 km 2 . Analysis and interpretation of the available information on the geological evolution provides no indication that erosion would expose the confining units above the Opalinus Clay within the next million years. The Opalinus Clay in the Zuercher Weinland is quite homogeneous and about 110 m thick. The properties of this rock are examined and found to be favourable for a repository. The dominance of the fine grain size and the high clay content indicate a very low hydraulic conductivity suitable for the isolation of radioactive wastes. Pore water extracted from drill-core samples is saline and has remained trapped for millions of years

  20. Fracture transmissivity as a function of normal and shear stress: first results in Opalinus Clay

    Cuss, R.J.; Milodowski, A.; Noy, D.J.; Harrington, J.F.

    2010-01-01

    Document available in extended abstract form only. Rock-mass failure around openings is usually observed in the form of a highly complex fracture network (EDZ), which is heterogeneous in distribution around a circular tunnel opening because of the heterogeneous stress distribution. The orientation of stress with respect to the fracture network is known to be important. The complex heterogeneous stress trajectory and heterogeneous fracture network results in a broad range of stresses and stress directions acting on the open fracture network. During the open stage of a repository, stress will slowly alter as shear movements occur along the fractures, as well as other time-dependent phenomena. As the repository is back filled, the stress field is further altered as the backfill settles and changes volume because of re-saturation. Therefore, a complex and wide ranging stress regime and stress history will result. In a purely mechanical sense, fracture transmissivity is a function of normal stress, shear stress, and fracture aperture. The Selfrac test from Mont Terri showed the change in transmissivity with effective normal stress. This work showed that fracture transmissivity decreased with increasing normal load and that an effective normal stress of 2.5 MPa is sufficient to yield a transmissivity similar to that seen in intact Opalinus clay (OPA). Therefore fracture closure because of normal stresses has been proven to be a quite efficient mechanism in OPA. A new shear rig was designed to investigate the detail of fracture transmissivity in OPA. The experimental configuration uses two prepared blocks that are 60 x 60 mm in size and approximately 20 mm thick. The first test sample had machine ground surfaces in contact with each other, with pore fluid being delivered through the centre of the top block directly to the fracture surface. The experimental programme included two distinct stages. In the first normal load was altered to investigate fracture transmissivity

  1. Geomechanical analysis of excavation-induced rock mass behavior of faulted Opalinus clay at the Mont Terri underground rock laboratory (Switzerland)

    Thoeny, R.

    2014-01-01

    Clay rock formations are potential host rocks for deep geological disposal of nuclear waste. However, they exhibit relatively low strength and brittle failure behaviour. Construction of underground openings in clay rocks may lead to the formation of an excavation damage zone (EDZ) in the near-field area of the tunnel. This has to be taken into account during risk assessment for waste-disposal facilities. To investigate the geomechanical processes associated with the rock mass response of faulted Opalinus Clay during tunnelling, a full-scale ‘mine-by’ experiment was carried out at the Mont Terri Underground Rock Laboratory (URL) in Switzerland. In the ‘mine-by’ experiment, fracture network characteristics within the experimental section were characterized prior to and after excavation by integrating structural data from geological mapping of the excavation surfaces and from four pre- and post-excavation boreholes.The displacements and deformations in the surrounding rock mass were measured using geo-technical instrumentation including borehole inclinometers, extensometers and deflectometers, together with high-resolution geodetic displacement measurements and laser scanning measurements on the excavation surfaces. Complementary data was gathered from structural and geophysical characterization of the surrounding rock mass. Geological and geophysical techniques were used to analyse the structural and kinematic relationships between the natural and excavation-induced fracture network surrounding the ‘mine-by’ experiment. Integrating the results from seismic refraction tomography, borehole logging, and tunnel surface mapping revealed that spatial variations in fault frequency along the tunnel axis alter the rock mass deformability and strength. Failure mechanisms, orientation and frequency of excavation-induced fractures are significantly influenced by tectonic faults. On the side walls, extensional fracturing tangential to the tunnel circumference was the

  2. Geomechanical analysis of excavation-induced rock mass behavior of faulted Opalinus clay at the Mont Terri underground rock laboratory (Switzerland)

    Thoeny, R.

    2014-07-01

    Clay rock formations are potential host rocks for deep geological disposal of nuclear waste. However, they exhibit relatively low strength and brittle failure behaviour. Construction of underground openings in clay rocks may lead to the formation of an excavation damage zone (EDZ) in the near-field area of the tunnel. This has to be taken into account during risk assessment for waste-disposal facilities. To investigate the geomechanical processes associated with the rock mass response of faulted Opalinus Clay during tunnelling, a full-scale ‘mine-by’ experiment was carried out at the Mont Terri Underground Rock Laboratory (URL) in Switzerland. In the ‘mine-by’ experiment, fracture network characteristics within the experimental section were characterized prior to and after excavation by integrating structural data from geological mapping of the excavation surfaces and from four pre- and post-excavation boreholes.The displacements and deformations in the surrounding rock mass were measured using geo-technical instrumentation including borehole inclinometers, extensometers and deflectometers, together with high-resolution geodetic displacement measurements and laser scanning measurements on the excavation surfaces. Complementary data was gathered from structural and geophysical characterization of the surrounding rock mass. Geological and geophysical techniques were used to analyse the structural and kinematic relationships between the natural and excavation-induced fracture network surrounding the ‘mine-by’ experiment. Integrating the results from seismic refraction tomography, borehole logging, and tunnel surface mapping revealed that spatial variations in fault frequency along the tunnel axis alter the rock mass deformability and strength. Failure mechanisms, orientation and frequency of excavation-induced fractures are significantly influenced by tectonic faults. On the side walls, extensional fracturing tangential to the tunnel circumference was the

  3. Environmental degradation of Opalinus Clay with cyclic variations in relative humidity

    Wild, Katrin; Walter, Patric; Madonna, Claudio; Amann, Florian

    2016-04-01

    Clay shales are considered as favorable host rocks for nuclear waste repositories due to their low permeability, high sorption capacity and the potential for self-sealing. However, the favorable characteristics of the rock mass may change during tunnel excavation. Excavation is accompanied by stress redistribution and the development of an excavation damage zone. Furthermore, unloading and exposure to atmospheric conditions with a lower relative humidity (RH) causes desaturation of the rock mass close to the tunnel. This leads to shrinkage and the formation of desiccation cracks. During the open drift stage, seasonal atmospheric changes, especially RH variations, may alter the rock mass and influence the long-term crack evolution. This contribution discusses the influence of RH variation on the mechanical behavior of OPA. A series of specimens were exposed to short-term and long-term, stepwise cyclic RH variations between about 60 and 95% at constant temperature. Strains were measured using strain gauges to monitor the volumetric response during RH cycles. After each applied RH cycle, Brazilian tensile strength (BTS) tests were performed to identify whether there is a change in tensile strength due to environmental damage caused by the change in RH. Swelling and shrinkage of the specimens accompanied by irreversible volumetric expansion was observed as a consequence of the exposure to RH cycles. However, the irreversible strain was limited to the direction normal to bedding suggesting that internal damage is restricted along the bedding planes. No significant effect of cyclic RH variations on the BTS of the specimens was observed. The strength parallel to bedding remained constant over several cycles while the strength normal to bedding shows a slightly decreasing trend after 2 cycles. Furthermore, the water retention characteristics of the specimens were not altered significantly during stepwise RH cycling as the evolution of the water content was reversible

  4. Hydro-mechanical analysis of results acquired by video-observations and deformation measurements performed in boreholes in the Opalinus clay of the URL Mont Terri supported by laboratory investigations on the hydro-mechanical behaviour of Opalinus clay

    Seeska, R.; Rutenberg, M.; Lux, K.H.

    2012-01-01

    Document available in extended abstract form only. Seven different boreholes in the Opalinus Clay formation of the Mont Terri Underground Rock Laboratory (URL Mont Terri) have been investigated by the Clausthal University of Technology (TUC) in cooperation with different partners with time, namely the National Cooperative for the Disposal of Radioactive Waste (NAGRA), the Federal Institute for Geosciences and Natural Resources (BGR) as well as the Swiss Federal Institute of Technology Zurich (ETHZ) and the Swiss Federal Nuclear Safety Inspectorate (ENSI). Aim of the investigations was to gain a large amount of high-quality and significant information on rock mass behaviour that can be used to increase knowledge about and improve understanding of time-dependent load-bearing and deformation behaviour of Opalinus Clay including pore water influences. For this purpose, an axial borehole camera and a three-arm calliper have been used. High-quality information on the load-bearing and deformation behaviour of the investigated boreholes was generated by the measurement and monitoring techniques used in the research project. The recordings reveal great as well as occasionally unexpected differences regarding the load-bearing behaviour as well as differences regarding the hydro-mechanical behaviour of the observed boreholes. While most of the boreholes have proved to be rather stable with only partial failure of the borehole wall in some areas, a complete borehole wall collapse occurred in two of the observed boreholes. The differences regarding the borehole wall stability and also the differences between the appearances of the occurring failure mechanisms are very likely due to the different orientation, the different locations within the URL Mont Terri, and the different facies the boreholes are located in. Figure 1 shows the time-dependent development of a borehole wall instability in one of the observed boreholes in a borehole section where an increase of moisture could

  5. Monitoring the Excavation Damaged Zone in Opalinus clay by three dimensional reconstruction of the electrical resistivity in the Mont Terri gallery G-04

    Lesparre, N.; Adler, A.; Nicollin, F.; Gibert, D.; Nussbaum, C.

    2012-04-01

    The characteristics of opalinus clay have been studied in the last years for its capacity to retain radionuclide transport as a low permeable rock. This formation presents thereby suitable properties for hosting repository sites of radioactive waste. The Mont Terri underground rock laboratory (Switzerland) has been excavated in opalinus clay layer in order to develop experiences improving the knowledge on the physico-chemical properties of the rock. The study of electrical properties furnishes information on the rock structure, its anisotropy and the changes of these properties with time (Nicollin et al., 2010 ; Thovert et al., 2011). Here the three dimensional reconstruction of the electrical resistivity aims at monitoring the temporal evolution of the excavation damaged zone. Three rings of electrodes have been set-up around the gallery and voltage is measured between two electrodes while a current is injected between two others (Gibert et al., 2006). Measurements have been achieved from July 2004 until April 2008 before, during and after the excavation of the gallery 04. In this study we develop a computational approach to reconstruct three dimensional images of the resistivity in the vicinity of the electrodes. A finite element model is used to represent the complex geometry of the gallery. The measurements inferred from a given resistivity distribution are estimated using the software EIDORS (Adler and Lionheart, 2006), this constitutes the forward problem. The reconstruction of the media resistivity is then implemented by fitting the estimated to the measured data, via the resolution of an inverse problem. The parameters of this inverse problem are defined by mapping the forward problem elements into a coarser mesh. This allows to reduce drastically the number of unknowns and so increases the robustness of the inversion. The inversion is executed with the conjugate gradient method regularised by an analysis of the Jacobian singular values. The results show an

  6. Expertise on the provision of evidence with respect to Nagra's disposal concept for spent fuel assemblies, vitrified high-level radioactive waste as well as for long-living intermediate-level wastes (Opalinus clay project)

    2005-08-01

    Mankind has been living in a field of natural radiation; in Switzerland, the natural dose is around 3 mSv per year. It can be assumed that an artificial dose smaller than the natural one is harmless and can therefore be tolerated. However, nuclear power plants, medicine, industry and research produce radioactive wastes whose radioactivity is mostly higher than the natural level. These wastes must therefore be concentrated and enclosed until the decay reduces the dose rate to a harmless level. For this, it is foreseen that the radioactive wastes will be disposed of in deep-lying geological strata. The enclosure must be guarantied in such a way that, at any time, the radiation suffered by mankind and environment due to the radioactive wastes stays under the statutory limit of 1 mSv/a. The judgement of the quality of the deep underground repository is divided into 3 chapters: a) based on the geological and hydro-geological properties of the host rock, the proof of safety shows that the chosen repository site is safe for the long term; b) the proof of site guaranties that the repository needed can be built in the chosen host rock; c) the proof of implementation demonstrates that the repository can be built with the actual technical means proposed. The forecast for the development of the safety of the repository in the long term is fairly inaccurate, the most difficult factor being the developments in mankind's way of life. Therefore, conservative assumptions must be taken into account to cover even the most unlikely cases. The former project 'Gewaehr' presented by the National Co-operative for the Disposal of Nuclear Wastes (NAGRA) in 1978 was based on crystalline rock; it was rejected because it was not possible to find a sufficiently large area without geologic faults for the repository. In new investigations, NAGRA found a suitable layer of Opalinus clay in Zurich's Weinland. In the neighbourhood of the layer discovered, there are neither noticeable beds of other

  7. Project Entsorgungsnachweis, 'Demonstration of disposal feasibility for SF/HLW/ILW in the Opalinus Clay of the Zuercher Weinland', Background, Objectives and Overview

    Schneider, Juerg; Zuidema, P.

    2004-01-01

    Juerg Schneider (Nagra, Switzerland) described the project on the Opalinus Clay (Project Entsorgungsnachweis, demonstration of disposal feasibility for SF/HLW/ILW in the Opalinus Clay of the Zuercher Weinland) for which the main objective is to demonstrate disposal feasibility and to provide input to the decision how to proceed. The report structure was described, the focus of the presentation being the report that aimed to provide a comprehensive assessment of long-term safety. The current situation was described in the presentation as follows: - The key need is to provide arguments for having proposed a good system for which there is sufficient understanding to allow a credible safety evaluation. - Alternative options exist, on which attention is maintained by a task-force. However, Nagra is confident in its results on Project Entsorgungsnachweis, given the knowledge base that currently exists, and has put forward a proposal, for consideration by the Swiss Government, to focus future work on the Opalinus Clay (OPA) of the Zuercher Weinland. - Making the safety case requires a proper integration of science, engineering and safety assessment. - Three key issues were identified in making a safety case: completeness, sufficient safety, and robustness to diminish the importance of uncertainties. - A safety case needs to be adequate to support a decision to proceed to the next stage in the programme, with multiple arguments including the existence of reserve FEP's. - The interacting functions of the relevant teams were viewed as a key component of the process of preparing a safety case: management; science; safety assessment; bias audit. During the discussion, the role of the bias team was recognised as being helpful to ensure completeness, as well as using the NEA FEP database as a check list. When speaking about sufficient safety, it should not imply predictive capability but rather that there is enough confidence in the current level of understanding to

  8. Engineered barrier emplacement experiment in Opalinus clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C.; Garcia-Sineriz, J. L.; Alonso, E.; Alheid, H. J.; Blumbling, P.

    2005-01-01

    The EB project aims at demonstrating the technical feasibility and studying the behaviour of near field components of a high level radioactive waste repository in clay rock. The project consists of an in situ test, a series of complementary laboratory tests as well as modelling work. The project is coordinated by ENRESA (Spain) and the work is being executed by the following organizations: AITEMIN and UPC-DIT (Spain) NAGRA (Switzerland) BGR (Germany) The project is co-funded by the European Commission (contract FIKW-CT-2000-00017) and by the Swiss Federal Office for Education and Science. This report includes a synthesized description of the project from its conception until approximately one and a half years after completion of the installation of the large-scale test (October 2000 to November 30, 2003). The project is described in detail in a series of specific reports. Chapter 9, References, includes the titles of these reports. Although each participating group wrote the sections on their particular work, this report is the result of the technical review, and editing carried out by M. Velasco and J. Farias (Technical Secretariat, ST) under the direction of J.C. Mayor (Project Director, ENRESA). In addition to this preface, and the following executive summary, the report is structured on the basis of nine chapters, the general contents of which are indicated below. Chapter 1 describes, in general terms, the different parts of the project, as well as the justification, objectives, expected results, and anticipated uncertainties. This chapter has been written by the ST, but the ideas are those of all the participating groups. Chapter 2 refers to the in situ test, describing the different test components and systems. Exception is made of the Granular Bentonite Material (GBM), which is described in Chapter 3, and of the geophysical systems for the seismic and electric characterization of near field of the clay rock, which are described in Chapter 4. Chapter 3 is

  9. Engineered barrier emplacement experiment in opalinus clay for the disposal of radioactive waste in underground repositories

    Mayor, J. C.; Garcia-Sineriz, J. L.; Alonso, E.; Alheid, H. J.; Blumbling, P.

    2005-01-01

    The EB project aims at demonstrating the technical feasibility and studying the behaviour of near field components of a high level radioactive waste repository in clay rock. The project consists of an in situ test, a series of complementary laboratory tests as well as modelling work. The project is coordinated by ENRESA (Spain) and the work is being executed by the following organizations:AITEMIN and UPC-DIT (Spain) NAGRA (Switzerland) BGR (Germany) The project is co-funded by the European Commission (contract FIKW-CT-2000-00017) and by the Swiss Federal Office for Education and Science. This report includes a synthesized description of the project from its conception until approximately one and a half years after completion of the installation of the large-scale test (October 2000 to November 30, 2003). The project is described in detail in a series of specific reports. Chapter 9, References, includes the titles of these reports. Although each participating group wrote the sections on their particular work, this report is the result of the technical review, and editing carried out by M. Velasco and J. Farias (Technical Secretariat, ST) under the direction of J.C. Mayor (Project Director, ENRESA). In addition to this preface, and the following executive summary, the report is structured on the basis of nine chapters, the general contents of which are indicated below. Chapter 1 describes, in general terms, the different parts of the project, as well as the justification, objectives, expected results, and anticipated uncertainties. This chapter has been written by the ST, but the ideas are those of all the participating groups. Chapter 2 refers to the in situ test, describing the different test components and systems. Exception is made of the Granular Bentonite Material (GBM), which is described in Chapter 3, and of the geophysical systems for the seismic and electric characterization of near field of the clay rock, which are described in Chapter 4. Chapter 3 is

  10. Pore-water evolution and solute-transport mechanisms in Opalinus Clay at Mont Terri and Mont Russelin (Canton Jura, Switzerland)

    Mazurek, M. [Institute of Geological Sciences, University of Berne, Berne (Switzerland); Haller de, A. [Earth and Environmental Sciences, University of Geneva, Geneva (Switzerland)

    2017-04-15

    Data pertinent to pore-water composition in Opalinus Clay in the Mont Terri and Mont Russelin anticlines have been collected over the last 20 years from long-term in situ pore-water sampling in dedicated boreholes, from laboratory analyses on drill cores and from the geochemical characteristics of vein infills. Together with independent knowledge on regional geology, an attempt is made here to constrain the geochemical evolution of the pore-waters. Following basin inversion and the establishment of continental conditions in the late Cretaceous, the Malm limestones acted as a fresh-water upper boundary leading to progressive out-diffusion of salinity from the originally marine pore-waters of the Jurassic low-permeability sequence. Model calculations suggest that at the end of the Palaeogene, pore-water salinity in Opalinus Clay was about half the original value. In the Chattian/Aquitanian, partial evaporation of sea-water occurred. It is postulated that brines diffused into the underlying sequence over a period of several Myr, resulting in an increase of salinity in Opalinus Clay to levels observed today. This hypothesis is further supported by the isotopic signatures of SO{sub 4}{sup 2-} and {sup 87}Sr/{sup 86}Sr in current pore-waters. These are not simple binary mixtures of sea and meteoric water, but their Cl{sup -} and stable water-isotope signatures can be potentially explained by a component of partially evaporated sea-water. After the re-establishment of fresh-water conditions on the surface and the formation of the Jura Fold and Thrust Belt, erosion caused the activation of aquifers embedding the low-permeability sequence, leading to the curved profiles of various pore-water tracers that are observed today. Fluid flow triggered by deformation events during thrusting and folding of the anticlines occurred and is documented by infrequent vein infills in major fault structures. However, this flow was spatially focussed and of limited duration and so did not

  11. Effects of post-disposal gas generation in a repository for low- and intermediate-level waste sited in the Opalinus Clay of Northern Switzerland. Technical report--08-07

    2008-10-01

    In Switzerland, Opalinus Clay was proposed as a possible host rock for a repository for low- and intermediate level radioactive waste (L/ILW). This rock is characterised by a low permeability and is therefore an excellent barrier against radionuclide transport. Because significant amounts of gas are generated in the repository, a demonstration is required that despite the low gas permeability of the Opalinus Clay the gas can escape without compromising long-term safety. The present study provides a comprehensive assessment of the question how gas generation and transport in an L/ILW repository affects the system behaviour. A geological repository for L/ILW in the Opalinus Clay of Northern Switzerland with a depth of about 300-400 m below the surface was assumed. The results of model calculations were used to optimise the layout of the repository with respect to the effects of gas generation and transport. Specifically a design option was studied in which, by an appropriate choice of backfill and sealing materials, the gas can escape along the access ramp into the overlying rock formations without creating undue gas overpressures. The estimates of the gas generation rates are based on a waste inventory accounting for the existing nuclear power plants, with an assumed operation period of 50 years, and for wastes from medicine, industry and research with a collection period up to the year 2050. This inventory includes a total mass of approximately 40,000 tons of steel and other metals and about 2,200 tons of organic matter. Complete corrosion/degradation of all gas-generating materials yields a gas volume of approximately 20 to 30 million cubic meters (STP). The highest gas generation rates are expected in the early post-closure period up to several hundreds of years, followed by a steady decline. The expected total duration of the gas generation phase is in the order of 200,000 years. The total pore volume in the backfilled repository is in the order of 58,000 m 3

  12. Project Opalinus clay Zuercher Weinland of Nagra. Evaluation of the geo-scientific data base and of the construction engineering aspects; Projekt Opalinuston Zuercher Weinland der Nagra. Beurteilung der erdwissenschaftlichen Datengrundlagen und der bautechnischen Machbarkeit

    NONE

    2005-02-15

    In this report the Commission for Nuclear Waste Management (KNE) assesses the geological and engineering aspects of the project Opalinus Clay, in which Nagra demonstrates the postclosure safety of geological disposal of spent fuel (SF), vitrified high-level wastes (HLW) and intermediate-level wastes (ILW) in a repository in the Opalinus Clay of the Zuercher Weinland in northern Switzerland. After in-depth examination of the geological database, KNE concludes that the demonstration of a suitable geological site for final disposal of SF, HLW and ILW in the Opalinus Clay of the Zuercher Weinland has been achieved. The geological assumptions Nagra uses for the assessment of long-term safety are based on data that have been carefully collected and interpreted. KNE acknowledges that Nagra interpreted the geological data correctly and adequately using state-of-the-art techniques. In case of lacking information, Nagra has used conservative or worst-case assumptions. The information documented by Nagra represents a good synthesis of field, laboratory and literature data. The tectonic situation of the Zuercher Weinland was examined in great details by Nagra. In the centre of the investigated region, where the Opalinus Clay occurs at 600 to 750 meters depth, the 3D-seismic data confirm its undisturbed stratification in an area of about 15 km{sup 2}. Analysis and interpretation of the available information on the geological evolution provides no indication that erosion would expose the confining units above the Opalinus Clay within the next million years. The Opalinus Clay in the Zuercher Weinland is quite homogeneous and about 110 m thick. The properties of this rock are examined and found to be favourable for a repository. The dominance of the fine grain size and the high clay content indicate a very low hydraulic conductivity suitable for the isolation of radioactive wastes. Pore water extracted from drill-core samples is saline and has remained trapped for millions of

  13. A review of materials and corrosion issues regarding canisters for disposal of spent fuel and high-level waste in Opalinus clay

    Landolt, D.; Davenport, A.; Payer, J.; Shoesmith, D.

    2009-01-01

    The project 'Entsorgungsnachweis' presented by NAGRA to the Swiss Federal Government in December 2002 assessed the feasibility of disposal of spent fuel (SF), vitrified high level waste (HLW) from reprocessing and long-lived intermediate level waste in an Opalinus Clay repository site in Northern Switzerland. NAGRA proposed the use of carbon steel canisters for disposal of SF/HLW and it also put forward an alternative concept of copper canisters with cast iron insert. In its reply the Federal Government acknowledged that NAGRA had successfully demonstrated the technical feasibility of disposal of SF/HLW. However, some of its experts raised a number of questions related to the choice of steel as canister material. Among others, it was questioned whether hydrogen formed by corrosion of steel in contact with saturated bentonite might adversely affect the barrier function of the Opalinus clay. It was also recommended that alternative canister materials and/or design concepts should be evaluated. To deal with these concerns NAGRA convened an international group of experts, the Canister Materials Review Board (CMRB), who were to review the existing information on canister materials that could be suitable for the proposed repository environment. Based on present knowledge of materials science, the CMRB was to recommend to NAGRA the most suitable material(s) for meeting the performance requirements for SF/HLW canisters. Specifically, the CMRB was to consider corrosion, including hydrogen generation, and stress-assisted failure processes that could affect the integrity and projected life time of SF/HLW canisters or impede the functioning of geological barriers while keeping in mind the overall feasibility of manufacturing, sealing and inspecting the canisters. The CMRB was further asked to identify the needs and provide advice for further studies by NAGRA on the long term performance and safety of SF/HLW canisters in the Swiss repository concept. For the assessment of the

  14. The geological evolution of opalinus clay in the Zurcher Weinland Area (ne Switzerland): learning from the past to predict future evolution and stability

    Gautschi, A.; Mazurek, M.

    2004-01-01

    A number of safety-relevant issues need to be addressed when considering long-term evolution of a radioactive waste repository, out of which uplift/erosion, fault activity, and changes in the geochemical and hydrogeological environment are particularly important. Among the strongest arguments in the prediction of future evolution is the extrapolation of events and processes that occurred over a long period of time in the geological past (e.g. 10 Ma) to a shorter period in the future. The future long-term evolution of Opalinus Clay in a potential siting area for a high-level waste repository in the Zurcher Weinland (NE Switzerland) is considered over a time period of around l Ma. The geological evolution or geological stability, respectively, can be predicted plausibly within reasonable limits over such a time period based on a detailed analysis of geological history. Predictions extending beyond this time period are feasible but contain an increasing element of uncertainty. This paper summarises the project-related conclusions, which are presented in greater detail in Nagra (2002a). (author)

  15. Microbiologically mediated processes in a repository sited in a clay host rock

    Schwyn, B.; Leupin, O. X.; Bagnoud, A.; Bernier-Latmani, R.

    2012-01-01

    Document available in extended abstract form only. Because of their favourable retention properties for radionuclides, clay-rich sediments are being considered in Switzerland as host rocks for the geological disposal of high, intermediate- and low-level radioactive waste. Compacted bentonite is foreseen as backfill material in the high level waste repository whereas for intermediate- and low-level waste the near field will mainly consist of cementitious material. The evolution of both types of repositories, which includes re-saturation, heat generation (only high level waste), near field degradation, gas production and radionuclide release may be impacted by microbial activity and vice versa. In this respect questions arise such as: - Are microorganisms present in a repository and its host rock? - Under which condition are microorganisms active in and around a repository? - In which processes are microorganisms involved? Various in situ experiments in a wide range of geological environments have evidenced the presence of microorganisms. Whether the microorganisms found in these in situ experiments are indigenous or introduced by drilling or/and excavation activities is still controversial. However, recent findings suggest the presence of indigenous microorganisms in Opalinus Clay. To conclusively answer the question about the origin of microorganisms, an international investigation programme has been launched to probe rock samples from the Underground Rock Laboratory at Mont Terri. So far, no metabolic activity has been observed in undisturbed clay rocks. Such activity may have ceased during diagenetic compaction of the sediment as suggested by the pore water composition measured in the Callovian-Oxfordian clayey formation of Bure (France). For the safety case of a repository the origin of microorganisms is of minor importance compared to the understanding of the conditions under which they might be metabolically active. Pore size distribution and connectivity can

  16. Expertise on the provision of evidence with respect to Nagra's disposal concept for spent fuel assemblies, vitrified high-level radioactive waste as well as for long-living intermediate-level wastes (Opalinus clay project); Gutachten zum Entsorgungsnachweis der Nagra fuer abgebrannte Brennelemente, verglaste hochaktive sowie langlebige mittelaktive Abfaelle (Projekt Opalinuston)

    NONE

    2005-08-15

    Mankind has been living in a field of natural radiation; in Switzerland, the natural dose is around 3 mSv per year. It can be assumed that an artificial dose smaller than the natural one is harmless and can therefore be tolerated. However, nuclear power plants, medicine, industry and research produce radioactive wastes whose radioactivity is mostly higher than the natural level. These wastes must therefore be concentrated and enclosed until the decay reduces the dose rate to a harmless level. For this, it is foreseen that the radioactive wastes will be disposed of in deep-lying geological strata. The enclosure must be guarantied in such a way that, at any time, the radiation suffered by mankind and environment due to the radioactive wastes stays under the statutory limit of 1 mSv/a. The judgement of the quality of the deep underground repository is divided into 3 chapters: a) based on the geological and hydro-geological properties of the host rock, the proof of safety shows that the chosen repository site is safe for the long term; b) the proof of site guaranties that the repository needed can be built in the chosen host rock; c) the proof of implementation demonstrates that the repository can be built with the actual technical means proposed. The forecast for the development of the safety of the repository in the long term is fairly inaccurate, the most difficult factor being the developments in mankind's way of life. Therefore, conservative assumptions must be taken into account to cover even the most unlikely cases. The former project 'Gewaehr' presented by the National Co-operative for the Disposal of Nuclear Wastes (NAGRA) in 1978 was based on crystalline rock; it was rejected because it was not possible to find a sufficiently large area without geologic faults for the repository. In new investigations, NAGRA found a suitable layer of Opalinus clay in Zurich's Weinland. In the neighbourhood of the layer discovered, there are neither

  17. Corrosion of carbon steel under anaerobic conditions in a repository for SF and HLW in Opalinus Clay. Technical report 08-12

    King, F.

    2008-10-01

    Nagra is considering carbon steel as one of the canister material options for the disposal of high level waste and spent fuel in a deep geological repository in Opalinus Clay. Following a brief period of aerobic conditions, the canister will be exposed to an anaerobic environment for much of its service life. Knowledge of the rate of anaerobic corrosion is important not only for estimating the canister lifetime but also for determining the rate of hydrogen generation. This report describes a critical review of the anaerobic corrosion behaviour of carbon steel under environmental conditions similar to those expected in the repository. The aims of the report are: 1. to recommend a (range of) long-term anaerobic corrosion rate(s) for carbon steel canisters, and 2. to justify the use of this rate in safety assessments based on a mechanistic understanding of the structure and properties of the protective corrosion product films. The review is based on selected studies from various national nuclear waste management programs, supplemented where appropriate with studies from other applications and with evidence from archaeological analogues. The corrosion rate of carbon steel decreases with time because of the formation of a protective surface film. There are differences in behaviour in bulk solution and in the presence of compacted bentonite. In bulk solution, the corrosion rate decreases to an apparent steady-state rate after a period of approximately six months, with a long-term rate of the order of 0.1 μm·.yr -1 . The surface film comprises a duplex structure, with a magnetite outer layer and a spinel-type inner layer. In compacted clay systems the rate of decrease in corrosion rate is slower, with steady state not being reached after several years of exposure. There is a significant body of evidence from apparently well-conducted experiments that indicate an anaerobic corrosion rate of the order of 1-2 μm·yr -1 in systems containing compacted clay and the

  18. Monte Carlo simulations of GeoPET experiments: 3D images of tracer distributions (18F, 124I and 58Co) in Opalinus clay, anhydrite and quartz

    Zakhnini, Abdelhamid; Kulenkampff, Johannes; Sauerzapf, Sophie; Pietrzyk, Uwe; Lippmann-Pipke, Johanna

    2013-08-01

    Understanding conservative fluid flow and reactive tracer transport in soils and rock formations requires quantitative transport visualization methods in 3D+t. After a decade of research and development we established the GeoPET as a non-destructive method with unrivalled sensitivity and selectivity, with due spatial and temporal resolution by applying Positron Emission Tomography (PET), a nuclear medicine imaging method, to dense rock material. Requirements for reaching the physical limit of image resolution of nearly 1 mm are (a) a high-resolution PET-camera, like our ClearPET scanner (Raytest), and (b) appropriate correction methods for scatter and attenuation of 511 keV—photons in the dense geological material. The latter are by far more significant in dense geological material than in human and small animal body tissue (water). Here we present data from Monte Carlo simulations (MCS) reflecting selected GeoPET experiments. The MCS consider all involved nuclear physical processes of the measurement with the ClearPET-system and allow us to quantify the sensitivity of the method and the scatter fractions in geological media as function of material (quartz, Opalinus clay and anhydrite compared to water), PET isotope (18F, 58Co and 124I), and geometric system parameters. The synthetic data sets obtained by MCS are the basis for detailed performance assessment studies allowing for image quality improvements. A scatter correction method is applied exemplarily by subtracting projections of simulated scattered coincidences from experimental data sets prior to image reconstruction with an iterative reconstruction process.

  19. Activation energies of the self-diffusion of HTO, 22Na+ and 36Cl- in a highly compacted argillaceous rock (Opalinus Clay)

    Loon, L.R. van; Mueller, W.; Iijima, K.

    2005-01-01

    The temperature dependence of the self-diffusion of HTO, 22 Na + and 36 Cl - in Opalinus Clay (OPA) was studied using a through-diffusion technique, in which the temperature was gradually increased in the steady state phase of the diffusion. The measurements were done on samples from two different geological locations. The dependence of the effective diffusion coefficient on temperature was found to be of an Arrhenius type in the temperature range between 0 and 70 deg. C. A slight difference between the two locations could be observed. The average value of the activation energy of the self-diffusion of HTO in OPA was 21.1 ± 1.6 kJ mol -1 , and 21.0 ± 3.5 and 19.4 ± 1.5 kJ mol -1 for 22 Na + and 36 Cl - , respectively. The measured values for HTO are slightly higher than the values found for the bulk liquid water (HTO: 18.8 ± 0.4 kJ mol -1 ). This indicates that the structure of the confined water in OPA might be slightly different from that of bulk liquid water. Also for Na + and Cl - , slightly higher values than in bulk liquid water (Na + : 18.4 kJ mol -1 ; Cl - : 17.4 kJ mol -1 ) were observed. The Stokes-Einstein relationship, based on the temperature dependency of the viscosity of bulk water, could not be used to describe the temperature dependence of the diffusion of HTO in OPA. This additionally indicates the slightly different structure of the pore water in OPA

  20. Hydrochemical characterisation of the opalinus clay in the test interval of the BDI-B1 borehole and on site pH, Eh, Fe(II) and alkalinity measurements

    Fernandez, A.M.; Turrero, M.J.; Yllera, A.; Melon, A.M.; Sanchez, M.D.; Pena, J.; Garralon, A.; Rivas, P. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Dpt. of Energy Environmental Impact, Madrid (Spain); Hernan, P. [ENRESA, Madrid (Spain)

    2005-07-01

    Clay formations are considered as a feasible option for the disposal of high-level radioactive wastes. In order to determine their suitability for this purpose, the evaluation of the hydro-geochemistry and transport mechanisms must be undertaken. In this sense, a general understanding of the basic physical and chemical processes that govern the solute transport together with a detailed site-characterization programme is required. To reach this goal, a number of activities have been developed in the Opalinus Clay formation at the Mont Terri Underground Research Laboratory (URL) at Switzerland. In the context of some experiments (WS-C, WS-D, WS-E, GM Task, DI, etc.), the Opalinus Clay formation has been comprehensively characterized to develop a conceptual, thermodynamic and transport model of solutes. The framework of these works is the need to know the mechanism of the possible migration of radionuclides and the pore water chemistry, as essential data for the performance assessment of such argillaceous systems. (authors)

  1. Characterization of the porosity in Boom (Mol site, Belgium) and Opalinus (Mont Terri, Switzerland) clays - about the benefit of using ion beam milling tools and CRYO-SEM

    Desbois, G.; Houben, M.E.; Sholokhova, Y.; Urai, J.L.; Kukla, P.A.

    2010-01-01

    imaging of pore space at high resolution. The first of them is to use ion beam milling tools able to prepare smooth, damage free cross-sectioned surfaces. Two main ion source are available: (1) a broad ion beam (BIB, up to 3.5 mA) is suitable to produce large polished cross-sections area of few mm 2 , while the focused ion beam (FIB, 1 pA - 45 nA) is better used for fine and precise polished cross-sections area of about few μm 2 . The second alternative is to preserve the in-situ nanostructures of wet clay-stones by using cryogenic techniques in order to stabilize in-situ fluids at temperature of liquid nitrogen. A FIB/BIB-cryo- SEM instrument combines cryo-techniques to preserve wet samples, in-situ sample preparation by ion beam cross-sectioning (BIB or FIB) and observations of the stabilized microstructure at high resolution (SEM). Since the ion beam is directly embedded into the SEM, this instrument offers a unique way to get a direct access of the pore space in 3D by using a 'slice and view' procedure equivalent to nano-serial sectioning. This procedure allows us investigating the natural in-situ pore space as a 3D matrix. This contribution reports on a study of Boom and Opalinus clays from reference sites for research (respectively at Mol site, Belgium and Mont Terri, Switzerland) using cryo-SEM at cryogenic temperature, with ion beam cross-sectioning to prepare smooth, damage free surfaces. Pores commonly have crack-like tips, preferred orientation parallel to bedding and power law size distribution. We define a number of pore types depending on shape and location in the microstructure. 3-D reconstruction by serial cross-sectioning shows 3-D connectivity of the pore space and provide natural pore matrix for simulation of permeability using Lattice Boltzmann method. These findings offer a new insight into the morphology of pores and quantification of porosity down to nano-scale and provide the basis for microstructure-based models of transport in clays

  2. Project Opalinus Clay: Radionuclide Concentration Limits in the Near-Field of a Repository for Spent Fuel and Vitrified High-Level Waste

    Berner, U

    2002-10-01

    The disposal feasibility study currently performed by Nagra includes a succession of quantitative models, aiming at describing the fate of radionuclides potentially escaping from the repository system. In this chain of models the present report provides the so called 'solubility limits' (maximum expected concentrations) for safety relevant radionuclides from SF/HLW wastes, disposed of in a reducing clay (Opalinus Clay, bentonite) environment. Solubility and speciation calculations in bentonite pore waters were performed using the very recently updated Nagra/PSI Chemical Thermodynamic Data Base (TDB) for the majority of the 37 elements addressed as potentially relevant. Particularly for the most relevant actinides, the straightforward applications with this updated TDB yielded results in contradiction to chemical analogy considerations. This was a consequence of incomplete data and called for problem specific TDB extensions, which were evaluated in a separate study. However, a summary of these problem specific extensions is provided in section 4.1. The results presented in this report solely depend on geochemical model calculations. Thus, it is of utmost importance that the underlying data and assumptions are made clear to the reader. In order to ensure traceability, all thermodynamic data not included in the Nagra/PSI TDB are explicitly specified in the report, in order to provide complete documentation for quality assurance and for comprehensibility. In order to clearly distinguish between results derived from data carefully reviewed in the Nagra/PSI TDB and those calculated from 'other' data, the summary of expected maximum concentrations provided in Table 1 includes two columns. The heading CALCULATED provides maximum concentrations based on data fully documented in the updated TDB, whereas maximum concentrations, which include additional problem specific data and/or data from other sources, are given under the heading RECOMMENDED. The

  3. Project Opalinus Clay: Radionuclide Concentration Limits in the Near-Field of a Repository for Spent Fuel and Vitrified High-Level Waste

    Berner, U.

    2002-10-01

    The disposal feasibility study currently performed by Nagra includes a succession of quantitative models, aiming at describing the fate of radionuclides potentially escaping from the repository system. In this chain of models the present report provides the so called 'solubility limits' (maximum expected concentrations) for safety relevant radionuclides from SF/HLW wastes, disposed of in a reducing clay (Opalinus Clay, bentonite) environment. Solubility and speciation calculations in bentonite pore waters were performed using the very recently updated Nagra/PSI Chemical Thermodynamic Data Base (TDB) for the majority of the 37 elements addressed as potentially relevant. Particularly for the most relevant actinides, the straightforward applications with this updated TDB yielded results in contradiction to chemical analogy considerations. This was a consequence of incomplete data and called for problem specific TDB extensions, which were evaluated in a separate study. However, a summary of these problem specific extensions is provided in section 4.1. The results presented in this report solely depend on geochemical model calculations. Thus, it is of utmost importance that the underlying data and assumptions are made clear to the reader. In order to ensure traceability, all thermodynamic data not included in the Nagra/PSI TDB are explicitly specified in the report, in order to provide complete documentation for quality assurance and for comprehensibility. In order to clearly distinguish between results derived from data carefully reviewed in the Nagra/PSI TDB and those calculated from 'other' data, the summary of expected maximum concentrations provided in Table 1 includes two columns. The heading CALCULATED provides maximum concentrations based on data fully documented in the updated TDB, whereas maximum concentrations, which include additional problem specific data and/or data from other sources, are given under the heading RECOMMENDED. The present study also pays

  4. Microbial investigations in Opalinus clay from Mont Terri and in Callovo-Oxfordian argillite from Meuse/Haute-Marne; Caracterisation microbiologique de l'argile a opalinus du Mont Terri et de l'argilite du callovo-oxfordien de Meuse/Haute-Marne

    Poulain, S

    2006-12-15

    The subject of this Ph.D. thesis deals with research achieved in the context of the Axis 2 of the law Bataille voted on December 30, 1991 about the possibility of building a deep geological repository for medium or high activity and long living nuclear waste. Nearby such a site, some microorganisms may influence the mobility of radionuclides coming from the waste canisters. This work consisted in looking for autochthonous microorganisms in the Opalinus clay formation from Mont Terri (Switzerland) and in the Callovo-Oxfordian argillite from Meuse/Haute-Marne (France). Microbial Investigations in these unknown unperturbed environments suggested very low microbial densities in the clayey sediments. However, new bacterial species could be isolated from those samples. In addition, a part of the allochthonous population, which has been introduced by air and human activity, could be identified in the Meuse/Haute-Marne underground research laboratory. (author)

  5. Microbial investigations in Opalinus clay from Mont Terri and in Callovo-Oxfordian argillite from Meuse/Haute-Marne; Caracterisation microbiologique de l'argile a opalinus du Mont Terri et de l'argilite du callovo-oxfordien de Meuse/Haute-Marne

    Poulain, S

    2006-12-15

    The subject of this Ph.D. thesis deals with research achieved in the context of the Axis 2 of the law Bataille voted on December 30, 1991 about the possibility of building a deep geological repository for medium or high activity and long living nuclear waste. Nearby such a site, some microorganisms may influence the mobility of radionuclides coming from the waste canisters. This work consisted in looking for autochthonous microorganisms in the Opalinus clay formation from Mont Terri (Switzerland) and in the Callovo-Oxfordian argillite from Meuse/Haute-Marne (France). Microbial Investigations in these unknown unperturbed environments suggested very low microbial densities in the clayey sediments. However, new bacterial species could be isolated from those samples. In addition, a part of the allochthonous population, which has been introduced by air and human activity, could be identified in the Meuse/Haute-Marne underground research laboratory. (author)

  6. Burial history of two potential clay host formations in Belgium

    Mertens, J.; Wouters, L.; Van Marcke, Ph.

    2004-01-01

    When dealing with long term stability of repository host rocks, it is important to consider and learn from all past geological events since the deposition of the formations. The burial history of the Boom Clay and Ypresian Clays, both considered as potential host rocks in Belgium, illustrates that the North Belgian region was tectonically relatively stable since deposition. In Northern Belgium, where both formations are located at a few hundreds meters of depth, tectonic movements were relatively small and no significant uplifts took place. The burial history of the Boom Clay in Mol, where the HADES underground research facility is located illustrates this. On the poster, the burial history for both formations is presented at two locations each: one location in the outcrop region and one research site location, where the formation is currently buried under a few 100 metres of sediment. (authors)

  7. Diffusion of HTO, {sup 36}Cl{sup -}, {sup 125}I{sup -} and {sup 22}Na{sup +} in Opalinus Clay: Effect of Confining Pressure, Sample Orientation, Sample Depth and Temperature

    Van Loon, L.R.; Soler, J.M

    2004-02-01

    Effective diffusion coefficients (D{sub e}), rock capacity factors ({alpha}) and diffusion-accessible porosities ({epsilon}) were measured using the through-diffusion technique. Transport (diffusion) was measured both perpendicular and parallel to the bedding. Special cells that allowed the application of an axial confining pressure were designed. The pressures applied ranged from 1 to 5 MPa for Mont Terri samples and between 4 and 15 MPa for Benken samples, the upper values representing the in-situ confining pressure at both locations. The test solutions used in the experiments were synthetic Opalinus Clay pore water, which has Na and Cl as main components (Mont Terri: I = 0.39 M; Benken: I = 0.20 M). Pressure only had a small effect on the value of the effective diffusion coefficients. In the case of Mont Terri samples, increasing the pressure from 1 to 5 MPa resulted in a decrease of the effective diffusion coefficient of 20% for HTO, 27% for {sup 36}Cl{sup -}, 29% for {sup 125}I{sup -} and 17 % for {sup 22}Na{sup +}. In the case of Benken samples, increasing the pressure from 4 to 15 MPa resulted in a decrease of D{sub e} of 17% for HTO, 22% for {sup 36}Cl{sup -}, 32% for {sup 125}I{sup -} and 17 % for {sup 22}Na{sup +}. Moreover, the effective diffusion coefficients for for {sup 36}Cl{sup -}are smaller than for HTO, which is consistent with an effect arising from anion exclusion. This ion exclusion effect is smaller in samples from Mont Terri than in samples from Benken, which can be explained by the higher ionic strength of the Mont Terri water used in the experiments. The diffusion of {sup 22}Na{sup +} is similar to that of HTO in the case of Mont Terri OPA. For Benken OPA, the D{sub e} value of {sup 22}Na{sup +} is a factor of 2 higher than that of HTO. This last observation cannot be explained so far but is comparable to experimental data from ANDRA (1999) on Callovo-Oxfordian claystones from the Meuse/Haute Same site. {sup 125}I{sup -} is retarded with

  8. Biogeochemical processes in a clay formation in situ experiment: Part A - Overview, experimental design and water data of an experiment in the Opalinus Clay at the Mont Terri Underground Research Laboratory, Switzerland

    Wersin, P., E-mail: paul.wersin@gruner.ch [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)] [Gruner Ltd., Gellertstrasse 55, 4020 Basel (Switzerland); Leupin, O.X. [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland); Mettler, S. [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)] [Solexperts Ltd., Mettlenbachstrasse 25, 8617 Moenchaltorf (Switzerland); Gaucher, E.C. [BRGM, 3 avenue Claude Guillemin, B.P. 36009, 45060 Orleans Cedex 2 (France); Maeder, U. [University of Bern, Institute of Geological Sciences, Baltzerstrasse 3, CH-3012 Bern (Switzerland); De Canniere, P. [SCK.CEN, Waste and Disposal Project, Boeretang 200, 2400 Mol (Belgium); Vinsot, A. [ANDRA, Laboratoire de Recherche Souterrain de Meuse/Haute-Marne, RD960 BP9, 55290 Bure (France); Gaebler, H.E. [BGR, Stilleweg 2, 30655 Hannover (Germany); Kunimaro, T. [JAEA, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kiho, K. [CRIEPI, 1646 Abiko, Abiko-city Chiba 270-1194 (Japan); Eichinger, L. [Hydroisotop, 85301 Schweitenkirchen (Germany)

    2011-06-15

    Highlights: > The composition was affected by the complex interplay of diffusion, mineral and surface reactions. > The {sup 13}C signals for carbon species showed significant variations which could only be partly explained. > The main cations remained remarkably constant during the experiment. > This underlines the strong buffering via cation exchange and carbonate dissolution/precipitation. - Abstract: An in situ test in the Opalinus Clay formation, termed porewater chemistry (PC) experiment, was carried out for a period of 5 years. It was based on the concept of diffusive equilibration whereby a traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed-off borehole. The main original focus was to obtain reliable data on the pH/pCO{sub 2} conditions of the porewater, but because of unexpected microbiologically-induced redox reactions, the objective was extended to elucidate the biogeochemical processes occurring in the borehole and to understand their impact on pH/pCO{sub 2} and porewater chemistry in the low permeability clay formation. The behaviour of the conservative tracers {sup 2}H and Br{sup -} could be explained by diffusive dilution in the clay and moreover the results showed that diffusive equilibration between the borehole water and the formation occurred within about 3 year's time. However, the composition and pH/pCO{sub 2} conditions differed considerably from those of the in situ porewater. Thus, pH was lower and pCO{sub 2} was higher than indicated by complementary laboratory investigations. The noted differences are explained by microbiologically-induced redox reactions occurring in the borehole and in the interfacial wall area which were caused by an organic source released from the equipment material. The degradation of this source was accompanied by sulfate reduction and - to a lesser extent - by methane generation, which induced a high rate of acetogenic reactions

  9. Biogeochemical processes in a clay formation in situ experiment: Part A - Overview, experimental design and water data of an experiment in the Opalinus Clay at the Mont Terri Underground Research Laboratory, Switzerland

    Wersin, P.; Leupin, O.X.; Mettler, S.; Gaucher, E.C.; Maeder, U.; De Canniere, P.; Vinsot, A.; Gaebler, H.E.; Kunimaro, T.; Kiho, K.; Eichinger, L.

    2011-01-01

    Highlights: → The composition was affected by the complex interplay of diffusion, mineral and surface reactions. → The 13 C signals for carbon species showed significant variations which could only be partly explained. → The main cations remained remarkably constant during the experiment. → This underlines the strong buffering via cation exchange and carbonate dissolution/precipitation. - Abstract: An in situ test in the Opalinus Clay formation, termed porewater chemistry (PC) experiment, was carried out for a period of 5 years. It was based on the concept of diffusive equilibration whereby a traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed-off borehole. The main original focus was to obtain reliable data on the pH/pCO 2 conditions of the porewater, but because of unexpected microbiologically-induced redox reactions, the objective was extended to elucidate the biogeochemical processes occurring in the borehole and to understand their impact on pH/pCO 2 and porewater chemistry in the low permeability clay formation. The behaviour of the conservative tracers 2 H and Br - could be explained by diffusive dilution in the clay and moreover the results showed that diffusive equilibration between the borehole water and the formation occurred within about 3 year's time. However, the composition and pH/pCO 2 conditions differed considerably from those of the in situ porewater. Thus, pH was lower and pCO 2 was higher than indicated by complementary laboratory investigations. The noted differences are explained by microbiologically-induced redox reactions occurring in the borehole and in the interfacial wall area which were caused by an organic source released from the equipment material. The degradation of this source was accompanied by sulfate reduction and - to a lesser extent - by methane generation, which induced a high rate of acetogenic reactions corresponding to very high acetate

  10. Support to other nuclear waste disposal programmes considering clay as a potential host rock

    Volckaert, G.

    2009-01-01

    SCK-CEN started to study the Boom Clay as potential host rock for nuclear waste disposal in 1974. Since then, SCK-CEN has been involved in other international projects studying clay as potential host rock in order to get a broader support for disposal in clay and to acquire broader insight in clay behaviour. Besides Belgium, France and Switzerland are currently investigating clay formations as potential host rock for the disposal of radioactive waste. In the Netherlands, clay formations have always been considered as an alternative to disposal in salt. The general interest in clays is increasing: in Germany and The United Kingdom, it was decided a few years ago that besides respectively salt and crystalline rock also clays need to be evaluated. In Eastern and Central Europe, the Slovak republic and Lithuania consider both clay and granite as possible host rocks for spent fuel while in Russia recently a project was started to study the possible disposal of low and medium level waste in a clay formation in the Leningrad area. Within the EC research and development framework programs and the OECD/NEA Clay Club, collaborations were developed between countries studying clay and with a strong involvement of SCK-CEN. The collaboration with the Eastern and Central European countries is supported through the support programme of the Belgian Ministry of Economic affairs. The objectives of these co-operations are to deliver expert services to other nuclear waste disposal programs considering clay as host rock; to to acquire broader international recognition of our expertise and support for the development of nuclear waste disposal in clay; to get a broader insight in the properties and behaviour of clays

  11. Self-sealing of excavation induced fractures in clay host rock

    Zhang, Chun-Liang [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Braunschweig (Germany)

    2015-07-01

    Excavation of an underground repository for disposal of radioactive waste in clay formations generates fractures around the openings, which may act as pathways for water transport and radionuclides migration. Because of the favorable properties of the clay rocks such as the rheological deformability and swelling capability, a recovery process of the excavation damaged zone (EDZ) can be expected due to the combined impact of rock compression, backfill resistance, and clay swelling during the post-closure phase. Another important issue is the impact of gases produced from anoxic corrosion of waste containers and other metallic components within the repository. The EDZ may act as a conduit for preferential gas flow, depending on the extent of the recovery process. For the safety assessment of a repository, the self-sealing behaviour and impact on water and gas transport through the EDZ have to be characterized, understood, and predicted. Recently, GRS has extensively investigated these important issues with various kinds of laboratory and in- situ experiments under relevant repository conditions. Test samples were taken from the Callovo-Oxfordian argillite at Bure in France and the Opalinus clay (shaly facies) at Mont Terri in Switzerland. Major findings are summarized as follows. As observed in laboratory and in-situ, the gas permeabilities of the claystones increase with stress-induced damage by several orders of magnitude from the impermeable state up to high levels of 10{sup -12}-10{sup -13} m{sup 2}. When hydrostatic confining stress is applied and increased, the fractures in the claystones tend to close up, leading to a decrease in gas permeability down to different levels of 10{sup -16}-10{sup -21} m{sup 2} at stresses in a range of 10 to 20 MPa. As water enters and flows through fractures, the clay matrix can take up a great amount of the water and expand into the interstices. Consequently, the hydraulic conductivity decreases dramatically by several orders of

  12. Thermal volume changes in clays and clay-stones

    Delage, P.; Sulem, J.; Mohajerani, M.; Tang, A.M.; Monfared, M.

    2012-01-01

    Document available in extended abstract form only. The disposal of high activity exothermic radioactive waste at great depth in clay host rocks will induce a temperature elevation that has been investigated in various underground research laboratories in Belgium, France and Switzerland through in-situ tests. Thermal effects are better known in clays (in particular Boom clay) than in clay-stone (e.g. Opalinus clay and Callovo-Oxfordian clay-stone). In terms of volume changes, Figure 1 confirms the findings of Hueckel and Baldi (1990) that volume changes depend on the over-consolidation ratio (OCR) of the clay. In drained conditions, normally consolidated clays exhibit plastic contraction when heated, whereas over-consolidated clay exhibit elastic dilation. The nature of thermal volume changes in heated clays obviously has a significant effect on thermally induced pore pressures, when drainage is not instantaneous like what occurs in-situ. Compared to clays, the thermal volume change behaviour of clay-stones is less well known than that of clays. clay-stone are a priori suspected to behave like over-consolidated clays. In this paper, a comparison of recent results obtained in the laboratory on the drained thermal volume changes of clay-stones is presented and discussed. It is difficult to run drained mechanical tests in clay-stones like the Opalinus clay and the Callovo-Oxfordian clay-stone because of their quite low permeability (10 -12 - 10 -13 m/s). This also holds true for thermal tests. Due to the significant difference in thermal expansion coefficient between minerals and water, it is necessary to adopt very slow heating rate (0.5 - 1 C/h) to avoid any thermal pressurization. To do so, a new hollow cylinder apparatus (100 mm external diameter, 60 mm internal diameter) with lateral drainages reducing the drainage length to half the sample thickness (10 mm) has been developed (Monfared et al. 2011). The results of a drained cyclic thermal test carried out on

  13. Geophysical monitoring of the EDZ during a gallery excavation in the Opalinus clay of the Mont Terri URL: anomalies of noble gases and self-potential associated with fractures and fluid dynamics in a horizontal borehole

    Maineult, A.; Mahiouz, K.; Lesparre, N.; Thomas, B.; Lavielle, B.; Nussbaum, C.; Wieczorek, K.; Gibert, D.; Kergosien, B.; Nicollin, F.

    2012-01-01

    Document available in extended abstract form only. The research underground rock laboratory (URL) of Mont Terri (Switzerland) was established in 1996 in a Mesozoic clay-stone formation (Opalinus Clay). It is aimed at studying the hydro-mechanical, thermal, geochemical and geophysical behaviour of argillaceous formations in the context of radioactive waste disposal. The EZ-G experiments were designed to monitor the EDZ evolution. The EZ-G08 experiment started in September 2007 to study the EDZ changes at different time scales during the tunnelling of gallery Ga08 starting from the northern part of the URL toward the end-face of the gallery Ga04. Before the excavation process started, we characterized the petrology and the structural properties of the core of the horizontal, 12-m long borehole BEZ-G5 drilled in the end-face of gallery Ga04 (first 2 meters in the shaly facies, the rest in the sandy facies). We quantified its noble gas content for studying gas transport processes in rocks and connected fracture networks. Depletion in He can be observed in the EDZ and other noble gases can also increase as desaturation processes occur. Inflows of water occurred in the borehole few weeks after its drilling until the junction of galleries Ga08 and Ga04. Water amounts of few litres were commonly released in other boreholes in the URL. We recorded the natural electrical potentials (self-potentials - SP), in BEZ-G5. SP originate from the movement of fluid, the diffusion of concentration or temperature gradients, and are sensitive to any change occurring in them. Borehole BEZ-G5 was equipped with a specific device, on which custom-made electrodes were fixed every 15 cm. The signals showed coherent perturbations during the drilling operations in the boreholes BEZ-G12 and in the end-face of the gallery Ga04. Afterwards, an early, strong but rather smooth increase of a few tens of mV, followed by a very slow decrease of much smallest amplitude, can be observed in some signals

  14. The Ypresian clays as alternative host rock for radioactive waste disposal in Belgium. A transferability study

    Van Baelen, Herve; Wouters, Laurent; Brassinnes, Stephane; Van Geet, Maarten; Vandenberghe, Noel

    2012-01-01

    Document available in extended abstract form only. For the long-term management of high-level and/or long-lived radioactive waste, ONDRAF/NIRAS advises deep geological repository in a plastic clay host rock. Since the seventies, Oligocene Boom Clay has been extensively studied for this purpose and is, in the Belgian context, considered as the reference host rock with Mol as the reference site for the RD and D. The alternative host rock, the Ypresian clays, has been studied for their basic properties, from the late nineties onwards, with Doel as reference site. This study aims at determining to which extent methodologies, knowledge and know-how can be transferred from Boom Clay to the Ypresian clays, in order to enhance the knowledge of this alternative without excessive research efforts. It evaluates the present knowledge of the Ypresian clays and figures out which elements are sufficiently known and understood, which elements of the Boom Clay can be reused and which need additional research. The Ypresian clays refer to a nearly continuous sequence of non-indurated, clayey layers, deposited early in the Eocene, in an open marine basin. It has a total thickness of 100 m or more and, in the area of interest, it occurs at a few hundreds of meters depth. Apart from a very slight tilt to the north, no major structures are known to affect the Ypresian clays in the investigated area. The lateral continuity inside the Ypresian clays might, however, be compromised by the potential occurrence of small-scale intra-formational faults. Two drilling campaigns, carried out in the framework of potential radioactive waste disposal, allowed to collect new data and describe and compare the Ypresian clays relative to Boom Clay. The grain size distribution of both clays is comparable. Although the minerals they are composed of are the same, the relative proportions within the clay fraction are significantly different, the Ypresian clays containing more smectite and swelling mixed

  15. Clay club initiative: self-healing of fractures in clay-rich host rocks

    Horseman, S.T.; Cuss, R.J.; Reeves, H.J.

    2004-01-01

    The capacity of fractures in argillaceous rocks to self-heal (or become, with the passage of time, less conductive to groundwater) is often cited as a primary factor favouring the choice of such materials as host rocks for deep disposal. The underlying processes which contribute to self-healing can be broadly subdivided into: (a) mechanical and hydro-mechanical processes linked to the change in the stress field, movement of pore water, swelling, softening, plastic deformation and creep, and (b) geochemical processes linked to chemical alterations, transport in aqueous solution and the precipitation of minerals. Since chemical alteration can cause profound changes to the mechanical properties of argillaceous rocks, it is often difficult to draw a firm line between these two subdivisions. Based on the deliberations of the recent Cluster Conference in Luxembourg, there would appear to be some support for the use of the term 'self-sealing' for processes affecting fracture conductivity in argillaceous rock that are largely mechanical or hydro-mechanical in their origin. There are four main areas in which the self-healing capacity of the host rock becomes relevant to repository design and performance assessment: - potential for radionuclide transport within the excavation damage zone (EDZ); - design and performance of repository sealing systems; - potential impact of gas migration; - long-term performance considering erosional unloading, seismicity and fault reactivation. The presence of an EDZ is acknowledged to be a particularly important issue in performance assessment. Interconnection of fractures in the EDZ could lead to the development of a preferential flow path extending along the emplacement holes, access tunnels and shafts of a repository towards overlying aquifers and the biosphere. In the preliminary French Safety Analyses, for example, the treatment of scenarios relating to early seal failure have highlighted the hydraulic role of the damaged zone as a

  16. Focusing on clay formation as host media of HLW geological disposal in China

    Zheng Hualing; Chen Shi; Sun Donghui

    2007-01-01

    Host medium is vitally important for safety for HLW geological disposal. Chinese HLW disposal effort in the past decades were mainly focused on granite formation. However, the granite formation has fatal disadvantage for HLW geological disposal. This paper reviews experiences gained and lessons learned in the international community and analyzes key factors affecting the site selection. It is recommended that clay formation should be taken into consideration and additional effort should be made before decision making of host media of HLW disposal in China. (authors)

  17. Do scaly clays control seismicity on faulted shale rocks?

    Orellana, Luis Felipe; Scuderi, Marco M.; Collettini, Cristiano; Violay, Marie

    2018-04-01

    One of the major challenges regarding the disposal of radioactive waste in geological formations is to ensure isolation of radioactive contamination from the environment and the population. Shales are suitable candidates as geological barriers. However, the presence of tectonic faults within clay formations put the long-term safety of geological repositories into question. In this study, we carry out frictional experiments on intact samples of Opalinus Clay, i.e. the host rock for nuclear waste storage in Switzerland. We report experimental evidence suggesting that scaly clays form at low normal stress (≤20 MPa), at sub-seismic velocities (≤300 μm/s) and is related to pre-existing bedding planes with an ongoing process where frictional sliding is the controlling deformation mechanism. We have found that scaly clays show a velocity-weakening and -strengthening behaviour, low frictional strength, and poor re-strengthening over time, conditions required to allow the potential nucleation and propagation of earthquakes within the scaly clays portion of the formation. The strong similarities between the microstructures of natural and experimental scaly clays suggest important implications for the slip behaviour of shallow faults in shales. If natural and anthropogenic perturbations modify the stress conditions of the fault zone, earthquakes might have the potential to nucleate within zones of scaly clays controlling the seismicity of the clay-rich tectonic system, thus, potentially compromising the long-term safeness of geological repositories situated in shales.

  18. Reactive transport simulations of the evolution of a cementitious repository in clay-rich host rocks

    Kosakowski, Georg; Berner, Urs; Kulik, Dmitrii A.

    2010-05-01

    that the clay mineral is represented by a X- '(solute) ligand' initially occupied with e.g. Na+. Our representation of cation exchange is based on a multi end-member ideal solid solution model for the clay which at the same time considers the chemical reactivity of the clay phase in the high pH cement environment. As a first application, we will present the results of calculations of the interaction between a cement compartment in contact with a clay-rich host rock. References: Bradbury, M. & Baeyens, B. (2002). Porewater chemistry in compacted re-saturated MX-80 bentonite: Physico-chemical characterisation and geochemical modelling. PSI-Report 02-10, Paul Scherrer Institut, Villigen, Switzerland. Lothenbach, B. & Wieland, E. (2006). A thermodynamic approach to the hydration of sulphate-resisting Portland cement. Waste Management, 26, 706-719. Shao, H., Dmytrieva, S.V., Kolditz, O., Kulik, D.A., Pfingsten, W. & Kosakowski, G. (2009). Modeling reactive transport in non-ideal aqueous-solid solution system. Applied Geochemistry, 24(7), 1287-1300.

  19. Multi-technical approach to characterize the dissolved organic matter from clay-stone

    Blanchart, Pascale; Michels, Raymond; Faure, Pierre; Parant, Stephane; Bruggeman, Christophe; De Craen, Mieke

    2012-01-01

    Document available in extended abstract form only. Currently, different clay formations (Boom Clay, Callovo-Oxfordian argilites, Opalinus Clay, Toarcian shales...) are studied as reference host rocks for methodological studies on the geological disposal of high-level and long-lived radioactive waste. While a significant effort is being done on the characterization of the mineral composition and the reactivity of the clays as barriers, the occurrence of organic matter, even in low proportion cannot be neglected. The organic matter appears as gas (C 1 -C 4 as identified in the Bure underground facilities), as solid (kerogen), as hydrocarbon liquids (free hydrocarbons within the kerogen or adsorbed on minerals) as well as in the aqueous phase (Dissolved Organic Matter - DOM). DOM raises specific interest, as it may have complexation properties towards metals and rare earth elements and is potentially mobile. Therefore, it is important to characterize the DOM as part of a study of feasibility of geological disposal. In this study, four host rocks were studied: - The Callovo-Oxfordian shales of Bure Underground Research Laboratory (Meuse, France); - The Opalinus Clay of Mont Terri Underground Research Laboratory (Switzerland); - The Toarcian shales of Tournemire (Aveyron, France); - The Boom Clay formation studied in The HADES Underground Research Laboratory (Mol, Belgium). Organic matter characteristics vary upon formation in terms of (i) origin (mainly marine type II; mixtures of marine type II and higher plants type III organic matter often poorly preserved), (ii) TOC contents, (iii) thermal maturity (for instance, Opalinus Clay and Toarcian shales are more mature and have poor oxygen content compare to Callovo-Oxfordian shales and Boom Clay). These differences in organic matter quality may have an influence on the quantity and the quality of DOM. The DOM of the rocks was isolated by Soxhlet extraction using pure water. A quantitative and qualitative multi

  20. Interaction between clay-based shaft seal components and crystalline host rock

    Priyanto, D.; Dixon, D.; Man, A.

    2010-01-01

    Document available in extended abstract form only. The Government of Canada has accepted the Nuclear Waste Management Organization's (NWMO) recommendation of Adaptive Phased Management (APM) as the long-term management approach for Canada's used nuclear fuel. APM ultimately involves the isolation and containment of used nuclear fuel deep in a Deep Geological Repository (DGR). On completion of waste emplacement operation and during repository closure, shaft seals, comprising clay-based shaft seal components, will be installed at strategic locations, such as where significant fracture zones (FZs) are located. The primary function of a shaft seal is to limit and prevent short-circuiting of the groundwater flow regime via the shaft. Currently, at Atomic Energy of Canada Limited's Underground Research Laboratory (URL) a full-scale shaft seal is being constructed at the intersection of a low dipping thrust fault called FZ 2 as part of the overall URL decommissioning activities. Both crystalline rock and sedimentary rock are considered potentially suitable host rocks formations for a DGR. This paper presents the results of numerical simulation of a shaft seal installed in moderately to sparsely fractured crystalline rock (MFR). The shape and thickness of the shaft seal modelled for a DGR in this exercise are similar to the shaft seal at the URL, but in the modelling exercise it is given a larger diameter (i.e. 7.30 m) equal to the assumed diameter of a production shaft of a repository. The seal consists of a blended bentonite-sand (BS) component that is constrained between two massive concrete seals. Dense backfill (DBF) materials are installed above and below the concrete seals (CS). The concrete seals are keyed into the access shaft to better anchor the concrete units in place and in order to restrain the swelling of the bentonite-sand component of the seal as it hydrates. The reference geosphere in the proposed work is MFR similar to the rock conditions

  1. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-01-01

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  2. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-06-20

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  3. Results of laboratory and in-situ measurements for the description of coupled thermo-hydro-mechanical processes in clays

    Goebel, Ingeborg; Alheid, Hans-Joachim [BGR Hannover, Stilleweg 2, D-30655 Hannover (Germany); Jockwer, Norbert [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Theodor-Heuss-Str. 4, 38122 Braunschweig (Germany); Mayor, Juan Carlos [ENRESA, Emilio Vargas 7, E-Madrid (Spain); Garcia-Sineriz, Jose Luis [AITEMIN, c/ Alenza, 1 - 28003 Madrid (Spain); Alonso, Eduardo [International Center for Numerical Methods in Engineering, CIMNE, Edificio C-1, Campus Norte UPC, C/Gran Capitan, s/n, 08034 Barcelona (Spain); Weber, Hans Peter [NAGRA, Hardstrasse 73, CH-5430 Wettingen (Switzerland); Ploetze, Michael [ETHZ, Eidgenoessische Technische Hochschule Zuerich, ETH Zentrum, HG Raemistrasse 101, CH-8092 Zuerich (Switzerland); Klubertanz, Georg [COLENCO Power Engineering Ltd, CPE, Taefern Str. 26, 5405 Baden-Daettwil (Switzerland); Ammon, Christian [Rothpletz, Lienhard, Cie AG, Schifflaendestrasse 35, 5001 Aarau (Switzerland)

    2004-07-01

    The Heater Experiment at the Mont Terri Underground Laboratory aims at producing a validated model of thermo-hydro-mechanically (THM) coupled processes. The experiment consists of an engineered barrier system where in a vertical borehole, a heater is embedded in bentonite blocks, surrounded by the host rock, Opalinus Clay. The experimental programme comprises permanent monitoring before, during, and after the heating phase, complemented by geotechnical, hydraulic, and seismic in-situ measurements as well as laboratory analyses of mineralogical and rock mechanics properties. After the heating, the experiment was dismantled for further investigations. Major results of the experimental findings are outlined. (authors)

  4. Interaction between clay-based sealing components and crystalline host rock

    Priyanto, D. G.; Dixon, D. A.; Man, A. G.

    The results of hydraulic-mechanical (H-M) numerical simulation of a shaft seal installed at a fracture zone (FZ) in a crystalline host rock using the finite element method are presented. The primary function of a shaft seal is to limit short-circuiting of the groundwater flow regime via the shaft in a deep geological repository. Two different stages of system evolution were considered in this numerical modelling. Stage 1 simulates the groundwater flow into an open shaft, prior to seal installation. Stage 2 simulates the groundwater flow into the shaft seal after seal installation. Four different cases were completed to: (i) evaluate H-M response due to the interaction between clay-based sealing material and crystalline host rock in the shaft seal structure; (ii) quantify the effect of the different times between the completion of the shaft excavation and the completion of shaft seal installation on the H-M response; and (iii) define the potential effects of different sealing material configurations. Shaft sealing materials include the bentonite-sand mixture (BSM), dense backfill (DBF), and concrete plug (CP). The BSM has greater swelling capacity and lower hydraulic conductivity ( K) than the DBF. The results of these analyses show that the decrease of the pore water pressure is concentrated along the fracture zone (FZ), which has the greatest K. As the time increases, the greatest decrease in pore water pressure is found around the FZ. Following FZ isolation and the subsequent filling of the shaft with water as it floods, the pore water pressure profile tends to recover back to the initial conditions prior to shaft excavation. The majority of the fluids that ultimately saturate the centre of the shaft seal flow radially inwards from the FZ. The time between the completion of the shaft excavation and the completion of shaft seal installation has a significant effect on the saturation time. A shorter time can reduce the saturation time. Since most of the inflow

  5. Geology of Northwestern Switzerland - with special emphasis on Opalinus Clay

    Burkhard, M.

    2007-01-01

    This report describes the variations of the geological structures of Northwestern Switzerland during about the last 200 million years. This gives an explanation for the present partition of the different rock layers in the studied domain. The geology of Switzerland is dominated by the formation of the Alps. The Mont Terri geology is best explained within the framework of the tectonic Wilson cycle: assembly of Pangea in Late Paleozoic times culminating in the Variscan orogeny, collapse and decay of this earlier mountain chain, peneplanation and new rifting leading to the opening of the alpine Tethys Ocean during the Mesozoic, followed by plate convergence, subduction, collision and new mountain-building in the Neogene. The Mont Terri geology bears witness to the same suite of events as the Alps; tectonically speaking, Mont Terri is part of the Alps. Africa continues to push Apulia against the larger European plate and the question arises as to what the geological future has in store for our hills and mountains. Recent GPS (Global Positioning System) data Iead to believe that it will be just erosion and decay

  6. Microbial analyses of clay and water from different samples from the Mont Terri Rock Laboratory (RL), Switzerland

    Sergeant, C.; Vesvres, M.H.; Barsotti, V.; Stroes-Gascoyne, S.; Hamon, C.J.; Neble, S.; Shippers, A.; Le Marrec, C.; Vinsot, A.; Schwyn, B.

    2010-01-01

    Document available in extended abstract form only. Exploration of deep subsurface microbial life has increased for very diverse motives. One of them is that these environments are potential host rocks for radioactive waste repositories and that microorganisms may influence geochemical conditions around such sites and migration properties of radionuclides. The pore water Chemistry experiment (PC) was conducted at the Mont Terri-RL to measure in situ the pH, Eh, and other geochemical parameters within the pore water of the Opalinus Clay formation. The borehole for PC was drilled with N 2 under clean but not aseptic conditions, filled immediately with synthetic pore water, which was circulated and monitored for five years. Soon after initiation of PC it was evident that microbial activity affected the borehole water geochemistry. Microbial analyses, including molecular biology and culturing methods, were performed repeatedly during PC (2003-2006), with detailed analysis of water and over-core clay upon termination in 2007. Results indicated the presence of heterotrophic aerobes and anaerobes, nitrate-reducers, iron-reducers, sulphate-reducers and Archaea, which together with geochemical data suggested a reducing environment with sulphate reduction in the water and adjacent clay. A black precipitate containing pyrite and a strong H 2 S smell confirmed the occurrence of sulphate reduction. Specific species identified (> 98% similarity) in PC water included Pseudomonas stutzeri, Bacillus licheniformis, and Desulfosporosinus sp., with similar and additional species (e.g., Trichococcus sp.; Koccuria sp.) in the clay. The origin of these (mostly anaerobic) species cannot be determined with certainty. Some species likely resulted from contamination, but others could be revived species indigenous in the Opalinus Clay. The microbial processes that occurred in PC are not representative of the processes in the undisturbed formation but illustrate the potential for microbial

  7. In situ determination of anisotropic permeability of clay

    Shao, H.; Soennke, J.; Morel, J.; Krug, S.

    2011-01-01

    Argillaceous formations are being considered as potential host rocks for repositories of radioactive waste in many countries. For this purpose, the thermal, hydraulic, mechanical, and chemical properties of the clay stone are being widely investigated in the laboratories and in situ. However, clay stone behaves, due to its tectonic evolution of the formation, hydraulically and mechanically transversal isotropic. Argillite bedding or layering structure has been observed in the underground laboratories Mont Terri in the Switzerland and Meuse/Haute-Marne at Bure site in France. Conventional packer systems used for the borehole hydraulic characterisation cannot distinguish the difference between the properties parallel and perpendicular to the bedding. For this purpose, a new 'slot packer' system has been developed by the BGR. This type of new packer system is intensively tested in the BGR laboratory and the Mont Terri Rock Laboratory to judge the feasibility. The anisotropic ratio of the Opalinus clay defined by permeability value parallel to the bedding/permeability value perpendicular to the bedding is evaluated up to eight times to one order of magnitude within the HG-B experiment in the Mont Terri Rock Laboratory. Within the cooperation between BGR and ANDRA, the 'slot packer' will be used for the measurement of anisotropic permeability of the Callovo-Oxfordian formation at the Bure site. (authors)

  8. Applying squeezing technique to clay-rocks: lessons learned from ten years experiments at Mont Terri

    Fernandez, A. M.; Melon, A.; Sanchez-Ledesma, D.M.; Tournassat, C.; Gaucher, E.; Astudillo, J.; Vinsot, A.

    2012-01-01

    Document available in extended abstract form only. Argillaceous formations of low permeability are considered in several countries as potential host rocks for the disposal of high level radioactive wastes (HLRW). In order to determine their suitability for waste disposal, evaluations of the hydro-geochemistry and transport mechanisms from such geologic formations to the biosphere must be undertaken. The migration of radionuclides through the geosphere will occur predominantly in the aqueous phase, and hence the pore water chemistry plays an important role in determining ion diffusion characteristics in argillaceous formations. Consequently, a great effort has been made to characterise the pore water chemistry in clay-rocks formations. In the last 10 years various techniques were developed for determining pore water composition of clay-rocks including both direct and indirect methods: 1) In situ pore water sampling (water and gas) from sealed boreholes (Pearson et al., 2003; Vinsot et al. 2008); 2) Laboratory pore water sampling from unaltered core samples by the squeezing technique at high pressures (Fernandez et al., 2009); and 3) Characterization of the water chemistry by geochemical modelling (Gaucher et al. 2009). Pore water chemistry in clay-rocks and extraction techniques were documented and reviewed in different studies (Sacchi et al., 2001). Recovering pristine pore water from low permeable and low water content systems is very difficult and sometimes impossible. Besides, uncertainties are associated to each method used for the pore water characterization. In this paper, a review about the high pressure squeezing technique applied to indurate clay-rocks was performed. For this purpose, the experimental work on Opalinus Clay at the Mont Terri Research Laboratory during the last ten years was evaluated. A complete discussion was made about different issues such as: a) why is necessary to obtain the pore water by squeezing in the context of radioactive waste

  9. The TIMODAZ project: Thermal impact on the damaged zone around a radioactive waste disposal in clay host rocks

    XiangLing, L.

    2009-01-01

    The management of spent nuclear fuel and other long-lived radio active waste is an important environmental issue today. Disposal in deep clay geological formations is one of the promising options to dispose of these wastes. In this context, the related research activities in the Euratom Framework Programme of European Commission are continually taking on an enhanced significance. The TIMODAZ is one of the STREP projects (Specific Targeted Research Project) in the Sixth EURATOM Framework Programme and contributes to the research related to the geological disposal of radioactive waste. The consortium is composed of a strong multidisciplinary team involving both European radioactive waste management organizations and nuclear research institutes, universities, industrial partners as well as consultancy companies (SME's). Totally, 15 partners coming from 8 countries are involved with a total budget of about 4000k EURO. Being the coordinator (through the EURIDICE expertise group), SCK-CEN plays the leading role in the project. Meanwhile, SCK-CEN participates the research in different work packages covering the laboratory tests, in-situ tests as well as the integration of TIMODAZ results within the safety case. An important item for the long-term safety of underground disposal is the proper evaluation of the DZ (damaged zone) in the clay host rock. The DZ is defined here as the zone of host rock that experiences THMC (Thermo-Hydro-Mechanical-Chemical) modifications induced by the repository, with potential major changes in the transport properties for radionuclides. The DZ is first initiated during the repository construction. Its behaviour is dynamic, dependent on changing conditions that vary from the open-drift period, to initial closure period and to the entire heating-cooling cycle of the decaying waste. The early THMC disturbances created by the excavation, the operational phase and the thermal load might be the most severe transient that the repository will undergo

  10. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  11. Biogeochemical processes in a clay formation in situ experiment: Part G - Key interpretations and conclusions. Implications for repository safety

    Wersin, P., E-mail: paul.wersin@gruner.ch [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)] [Gruner Ltd., Gellertstrasse 55, 4020 Basel (Switzerland); Stroes-Gascoyne, S. [Atomic Energy of Canada Limited (AECL), Whiteshell Laboratories, Pinawa, Manitoba, Canada R0E 1L0 (Canada); Pearson, F.J. [Ground-Water Geochemistry, 5108 Trent Woods Drive, New Bern, NC 28562 (United States); Tournassat, C. [BRGM, French Geological Survey, 3 Avenue Claude Guillemin, B.P. 36009, 45060 Orleans Cedex 2 (France); Leupin, O.X.; Schwyn, B. [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)

    2011-06-15

    . Nevertheless, the simulations provided additional evidence of the high pH buffer capacity of the Opalinus Clay. The results from the microbiological investigations do not allow unambiguous identification of the origin of the microbial population in the borehole. Possible sources were the drilling procedure, the artificial porewater, and perhaps some revival of indigenous dormant strains. Regardless of the origin of the microbes, the results from the PC experiment underlined the importance of anaerobic microbial activity in the 'disturbed' Opalinus Clay, facilitated by the introduction of space, water and organic material, in rapidly establishing very reducing conditions. The PC experiment also yielded valuable insight with regard to the safety of a high-level radioactive waste repository emplaced in Opalinus Clay. Anaerobic microbial perturbations in the clay host rock may occur from the construction and excavation procedures and emplaced organic by-products. The resulting effects on porewater chemistry, i.e., especially on pH and Eh, may affect the mobility of radionuclides eventually released from the waste. However, the overall results of the PC experiment suggest that such effects are temporary and spatially limited because of the large buffering capacity and diffusive properties of the clay formation. Nevertheless, the results also indicate that the amounts of organic materials in a high-level waste repository should be kept small in order to achieve background conditions within a short time period after repository closure. A further conclusion from the PC experiment is that commonly used equipment materials may not display commonly assumed inert behaviour. This particularly holds for the gel-type 'robust' reference electrodes, which may release substantial amounts of glycerol.

  12. From clay bricks to deep underground storage

    2012-05-01

    This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the use of clay strata for the storage of radioactive wastes in deep-lying repositories. First of all, a geological foray is made concerning the history of the use of clay and its multifarious uses. The characteristics of clay and its composition are examined and its formation in the geological past is explained. In particular Opalinus clay is looked at and the structures to be found are discussed. The clay's various properties and industrial uses are examined and its sealing properties are examined. Also, Bentonite clay is mentioned and work done by Nagra and co-researchers is noted

  13. Technetium migration in natural clays

    Luebke, Maria

    2015-01-01

    The present work was performed within the joint research project ''Retention of repository relevant radionuclides in argillaceous rocks and saline systems'' (contract no.: 02E10981), funded by the Federal Ministry for Economic Affairs and Energy (BMWi). The aim was to obtain first insights into the interaction of the long-lived fission product technetium and natural clay with regard to a repository for high-level nuclear waste. For this purpose Opalinus Clay from Mont Terri (northern Switzerland) was used as a reference material. The nuclide technetium-99 will contribute to the radiotoxicity of spent nuclear fuel for more than thousand years due to its long half-live. In case of a leakage of the storage vessels, the geochemistry of technetium is determined by its oxidation state, at which only the oxidation states +IV and +VII are relevant. Because of the high solubility and low affinity to sorption on surfaces of minerals, Tc(VII) is considered to be very mobile and thus the most hazardous species. The focuses of this study therefore are diffusion experiments with this mobile species and investigations of the effect of ferrous iron on the mobility and speciation of technetium.rnThe interaction of technetium and Opalinus Clay was studied in sorption and diffusion experiments varying several parameters (pH value, addition of reducing agents, effect of oxygen, diffusion pathways). In the course of this study spatially resolved investigations of the speciation have been performed on Opalinus Clay thin sections and bore cores for the first time. In addition to the speciation, further information regarding elemental distributions and crystalline phases near technetium enrichments were obtained. Supplementary investigations of powder samples allowed determining the molecular structure of technetium on the clay surface.rnBoth the combination of sorption experiments with spectroscopic investigations and the diffusion experiment exhibit a reduction of Tc

  14. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-01-01

    As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

  15. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

  16. Large scale laboratory diffusion experiments in clay rocks

    Garcia-Gutierrez, M.; Missana, T.; Mingarro, M.; Martin, P.L.; Cormenzana, J.L.

    2005-01-01

    Full text of publication follows: Clay formations are potential host rocks for high-level radioactive waste repositories. In clay materials the radionuclide diffusion is the main transport mechanism. Thus, the understanding of the diffusion processes and the determination of diffusion parameters in conditions as similar as possible to the real ones, are critical for the performance assessment of deep geological repository. Diffusion coefficients are mainly measured in the laboratory using small samples, after a preparation to fit into the diffusion cell. In addition, a few field tests are usually performed for confirming laboratory results, and analyse scale effects. In field or 'in situ' tests the experimental set-up usually includes the injection of a tracer diluted in reconstituted formation water into a packed off section of a borehole. Both experimental systems may produce artefacts in the determination of diffusion coefficients. In laboratory the preparation of the sample can generate structural change mainly if the consolidated clay have a layered fabric, and in field test the introduction of water could modify the properties of the saturated clay in the first few centimeters, just where radionuclide diffusion is expected to take place. In this work, a large scale laboratory diffusion experiment is proposed, using a large cylindrical sample of consolidated clay that can overcome the above mentioned problems. The tracers used were mixed with clay obtained by drilling a central hole, re-compacted into the hole at approximately the same density as the consolidated block and finally sealed. Neither additional treatment of the sample nor external monitoring are needed. After the experimental time needed for diffusion to take place (estimated by scoping calculations) the block was sampled to obtain a 3D distribution of the tracer concentration and the results were modelled. An additional advantage of the proposed configuration is that it could be used in 'in situ

  17. Geochemical porosity values obtained in core samples from different clay-rocks

    Fernandez, A.M.

    2010-01-01

    Document available in extended abstract form only. Argillaceous formations of low permeability are considered in many countries as potential host rocks for the disposal of high level radioactive wastes (HLRW). In order to determine their suitability for waste disposal, evaluations of the hydro-geochemistry and transport mechanisms from such geologic formations to the biosphere must be undertaken. One of the key questions about radionuclide diffusion and retention is to know the chemistry and chemical reactions and sorption processes that will occur in the rock and their effects on radionuclide mobility. In this context, the knowledge of the pore water chemistry is essential for performance assessment purposes. This information allows to establish a reliable model for the main water-rock interactions, which control the physico-chemical parameters and the chemistry of the major elements of the system. An important issue in order to model the pore water chemistry in clayey media is to determine the respective volume accessible to cations and anions, i.e, the amount of water actually available for chemical reactions/solute transport. This amount is usually referred as accessible porosity or geochemical porosity. By using the anion inventories, i.e. the anion content obtained from aqueous leaching, and assuming that all Cl - , Br - and SO4 2- leached in the aqueous extracts originates from pore water, the concentration of a conservative ion can be converted into the real pore water concentration if the accessible porosity is known. In this work, the accessible porosity or geochemical porosity has been determined in core samples belonging to four different formations: Boom Clay from Hades URL (Belgium, BE), Opalinus Clay from Mont Terri (Switzerland, CH), and Callovo-Oxfordian argillite from Bure URL (France, FR). The geochemical or chloride porosity was defined as the ratio between the pore water volume containing Cl-bearing pore water and the total volume of a sample

  18. Review of Studies of Clay Minerals as Significant Component of Potential Host Rocks or Engineering Barriers for Radioactive Waste Disposals Performed at Comenius University in Bratislava

    Peter, Uhlik; Vladimir, Sucha; Maria, Caplovicova; Igor, Stricek

    2013-01-01

    About 50 % of electric power is produced by nuclear power plants in Slovakia. In spite of the significant production of nuclear waste, Slovakia has not defined basic strategy of radioactive-waste isolation. However, some pilot projects and studies have been carried out. Five areas were determined as prospective sites for construction of deep geological repository (DGR). Two of them are situated in the south of Slovakia. Szecseny schlier (mixture of siltstones and Clay-stones) of Lucenec Formation (Egerian) is one of the most prospective host rocks from lithological, structural and spatial perspective. Besides the investigation of potential host rock for DGR the studies of bentonite properties as important part of engineering barriers for radioactive waste disposals were performed. Detailed mineral and structural analyses of smectites from the bentonitic material exposed to laboratory Mock-Up test were realised. Particular interest has been focused on interaction between Fe and smectites. Other field of interest is investigation of sorption of Cs and Sr on natural and modified bentonites, including irradiation. Purpose of this work is to present a short review of other studies done by our group with partial focusing to interaction of organic dye (Rhoda-mine 6G) with smectite that is connected with changes of layer charge after treatment; possibilities to measure preferential orientation of clays after compaction by TEM and to effort to use X-ray micro-tomography for inner structure of sediments. (authors)

  19. Geochemical of clay formations : study of Spanish clay REFERENCE

    Turrero, M. J.; Pena, J.

    2003-01-01

    Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

  20. Clay Play

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  1. Ball clay

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  2. From clay bricks to deep underground storage; vom lehmziegel bis zum tiefenlager -- anwendung von ton

    NONE

    2012-05-15

    This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the use of clay strata for the storage of radioactive wastes in deep-lying repositories. First of all, a geological foray is made concerning the history of the use of clay and its multifarious uses. The characteristics of clay and its composition are examined and its formation in the geological past is explained. In particular Opalinus clay is looked at and the structures to be found are discussed. The clay's various properties and industrial uses are examined and its sealing properties are examined. Also, Bentonite clay is mentioned and work done by Nagra and co-researchers is noted.

  3. Thermal effects on clay rocks for deep disposal of high-level radioactive waste

    Chun-Liang Zhang

    2017-06-01

    Full Text Available Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions: (1 stresses covering the range from the initial lithostatic state to redistributed levels after excavation, (2 hydraulic drained and undrained boundaries, and (3 heating from ambient temperature up to 90 °C–120 °C and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.

  4. Clay Houses

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  5. pH-dependent Pu interaction of one bacterial isolate from Mont Terri Opalinus Clay

    Moll, Henry; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Biogeochemistry

    2016-07-01

    Sporomusa sp. MT-2.99 cells displayed a strong pH dependent affinity for Pu. Relatively high maximal Pu loadings as for instance 230 mgPu/g{sub dry} {sub biomass} for Sporomusa sp. at pH 6.1 were achieved. A much slower abiotic reduction of Pu(VI) was observed at pH 4 compared to pH 6.1. Independent on pH an enrichment of Pu(V) in the supernatant and of Pu(IV)- polymers on the biomass was discovered.

  6. Addendum to: Derivation of in situ opalinus clay porewater compositions from experimental and geochemical modelling studies

    Bradbury, M.H.; Baeyens; Pearson, F.J.; Berner, U.

    1998-01-01

    As part of the synthesis of water chemistry studies within the hydrochemical program at Mont Terri (Switzerland), a reexamination of the modelling method showed that it should lead to a range of water compositions rather than to a single composition. The single composition resulted from two compensating oversights, a theoretical one and a modelling one. These are discussed in this Addendum. (author)

  7. Project Opalinus Clay: Radionuclide Concentration Limits in the Cementitious Near-Field of an ILW Repository

    Berner, U.

    2003-05-01

    The disposal feasibility study currently performed by Nagra includes a succession of quantitative models, aiming at describing the fate of radionuclides potentially escaping from the repository system. In this chain of models the present report provides the so called 'solubility limits' (maximum expected concentrations) for safety relevant radionuclides from ILW wastes, disposed of in a chemically reducing, cementitious environment. From a chemical point of view, the pore waters of hydrated cement matrices provide an exceptional environment. Compared with usual ground waters exhibiting pH-values of around 8, cement pore waters are strongly alkaline with pH-values from 12.5 to 13.5 and contain nearly no carbonate and only little sulfate. Oxides and hydroxides mainly determine solubility and speciation of the elements. Solubility and speciation calculations in cementitious pore waters were performed using the very recently updated Nagra/PSI Chemical Thermodynamic Data Base (TDB) for the majority of the 36 elements addressed as potentially relevant. Wherever possible, maximum concentrations compiled in this report were based on geochemical calculations. In order to ensure full traceability, all thermodynamic data not included in the TDB are explicitly specified in the document. For similar reasons the compilation of results (Table 1) clearly distinguishes between calculated and recommended items. The heading 'CALCULATED' lists maximum concentrations based on data fully documented in the TDB; results under the heading 'RECOMMENDED' include data from other sources. The pH sensitivity of the results was examined by performing calculations at pH 13.4, in accordance with the pH of non-altered cement pore water. Solubility increases predominantly for elements that tend to form anionic hydroxide complexes (Sn, Pd, Zr, Ni, Eu, Cd, Mo, Co). Oxidizing conditions around +350 mV might be expected in the environment of nitrate-containing wastes. In this case, significant solubility increases were calculated for U, Np, Pu, Se and Ag. Special attention is allocated to the uncertainties of the evaluated maximum concentrations, expressed as upper- and lower limits. The conceptual steps to determine these uncertainties are explained in the section 3. Due to lack of data, it was not always possible to assess uncertainties in a manner consistent with that used to assess the solubility limits. For some elements, uncertainties had to be derived from less sharply defined data or even with the help of estimates. Such less rigorous approaches are justified by the fact that in performance assessments particularly the upper limits are as important as are the maximum concentrations themselves. However, appropriate information was available to define an upper limit for nearly all of the relevant nuclides. (author)

  8. Project Opalinus Clay: Radionuclide Concentration Limits in the Cementitious Near-Field of an ILW Repository

    Berner, U

    2003-05-01

    The disposal feasibility study currently performed by Nagra includes a succession of quantitative models, aiming at describing the fate of radionuclides potentially escaping from the repository system. In this chain of models the present report provides the so called 'solubility limits' (maximum expected concentrations) for safety relevant radionuclides from ILW wastes, disposed of in a chemically reducing, cementitious environment. From a chemical point of view, the pore waters of hydrated cement matrices provide an exceptional environment. Compared with usual ground waters exhibiting pH-values of around 8, cement pore waters are strongly alkaline with pH-values from 12.5 to 13.5 and contain nearly no carbonate and only little sulfate. Oxides and hydroxides mainly determine solubility and speciation of the elements. Solubility and speciation calculations in cementitious pore waters were performed using the very recently updated Nagra/PSI Chemical Thermodynamic Data Base (TDB) for the majority of the 36 elements addressed as potentially relevant. Wherever possible, maximum concentrations compiled in this report were based on geochemical calculations. In order to ensure full traceability, all thermodynamic data not included in the TDB are explicitly specified in the document. For similar reasons the compilation of results (Table 1) clearly distinguishes between calculated and recommended items. The heading 'CALCULATED' lists maximum concentrations based on data fully documented in the TDB; results under the heading 'RECOMMENDED' include data from other sources. The pH sensitivity of the results was examined by performing calculations at pH 13.4, in accordance with the pH of non-altered cement pore water. Solubility increases predominantly for elements that tend to form anionic hydroxide complexes (Sn, Pd, Zr, Ni, Eu, Cd, Mo, Co). Oxidizing conditions around +350 mV might be expected in the environment of nitrate-containing wastes. In this case, significant solubility increases were calculated for U, Np, Pu, Se and Ag. Special attention is allocated to the uncertainties of the evaluated maximum concentrations, expressed as upper- and lower limits. The conceptual steps to determine these uncertainties are explained in the section 3. Due to lack of data, it was not always possible to assess uncertainties in a manner consistent with that used to assess the solubility limits. For some elements, uncertainties had to be derived from less sharply defined data or even with the help of estimates. Such less rigorous approaches are justified by the fact that in performance assessments particularly the upper limits are as important as are the maximum concentrations themselves. However, appropriate information was available to define an upper limit for nearly all of the relevant nuclides. (author)

  9. A minimalistic microbial food web in an excavated deep subsurface clay rock.

    Bagnoud, Alexandre; de Bruijn, Ino; Andersson, Anders F; Diomidis, Nikitas; Leupin, Olivier X; Schwyn, Bernhard; Bernier-Latmani, Rizlan

    2016-01-01

    Clay rocks are being considered for radioactive waste disposal, but relatively little is known about the impact of microbes on the long-term safety of geological repositories. Thus, a more complete understanding of microbial community structure and function in these environments would provide further detail for the evaluation of the safety of geological disposal of radioactive waste in clay rocks. It would also provide a unique glimpse into a poorly studied deep subsurface microbial ecosystem. Previous studies concluded that microorganisms were present in pristine Opalinus Clay, but inactive. In this work, we describe the microbial community and assess the metabolic activities taking place within borehole water. Metagenomic sequencing and genome-binning of a porewater sample containing suspended clay particles revealed a remarkably simple heterotrophic microbial community, fueled by sedimentary organic carbon, mainly composed of two organisms: a Pseudomonas sp. fermenting bacterium growing on organic macromolecules and releasing organic acids and H2, and a sulfate-reducing Peptococcaceae able to oxidize organic molecules to CO(2). In Opalinus Clay, this microbial system likely thrives where pore space allows it. In a repository, this may occur where the clay rock has been locally damaged by excavation or in engineered backfills. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Microorganisms in potential host rocks for geological disposal of nuclear waste and their interactions with radionuclides

    Cherkouk, A.; Liebe, M.; Luetke, L.; Moll, H.; Stumpf, T. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2015-07-01

    The long-term safety of nuclear waste in a deep geological repository is an important issue in our society. Microorganisms indigenous to potential host rocks are able to influence the oxidation state, speciation and therefore the mobility of radionuclides as well as gas generation or canister corrosion. Therefore, for the safety assessment of such a repository it is necessary to know which microorganisms are present in the potential host rocks (e.g. clay, salt) and if these microorganisms can influence the performance of a repository. Microbial diversity in potential host rocks for geological disposal of nuclear waste was analyzed by culture-independent molecular biological methods (e.g. 16S rRNA gene retrieval) as well as enrichment and isolation of indigenous microbes. Among other isolates, a Paenibacillus strain, as a representative of Firmicutes, was recovered in R2A media under anaerobic conditions from Opalinus clay from the Mont Terri in Switzerland. Accumulation experiments and potentiometric titrations showed a strong interaction of Paenibacillus sp. cells with U(VI) within a broad pH range (3-7). Additionally, the interactions of the halophilic archaeal strain Halobacterium noricense DSM 15987, a salt rock representative reference strain, with U(VI) at high ionic strength was investigated. After 48 h the cells were still alive at uranium concentrations up to 60 μM, which demonstrates that Halobacterium noricense can tolerate uranium concentrations up to this level. The formed uranium sorption species were examined with time-resolved laser-induced fluorescence spectroscopy (TRLFS). The results about the microbial communities present in potential host rocks for nuclear waste repositories and their interactions with radionuclides contribute to the safety assessment of a prospective nuclear waste repository.

  11. Microorganisms in potential host rocks for geological disposal of nuclear waste and their interactions with radionuclides

    Cherkouk, A.; Liebe, M.; Luetke, L.; Moll, H.; Stumpf, T.

    2015-01-01

    The long-term safety of nuclear waste in a deep geological repository is an important issue in our society. Microorganisms indigenous to potential host rocks are able to influence the oxidation state, speciation and therefore the mobility of radionuclides as well as gas generation or canister corrosion. Therefore, for the safety assessment of such a repository it is necessary to know which microorganisms are present in the potential host rocks (e.g. clay, salt) and if these microorganisms can influence the performance of a repository. Microbial diversity in potential host rocks for geological disposal of nuclear waste was analyzed by culture-independent molecular biological methods (e.g. 16S rRNA gene retrieval) as well as enrichment and isolation of indigenous microbes. Among other isolates, a Paenibacillus strain, as a representative of Firmicutes, was recovered in R2A media under anaerobic conditions from Opalinus clay from the Mont Terri in Switzerland. Accumulation experiments and potentiometric titrations showed a strong interaction of Paenibacillus sp. cells with U(VI) within a broad pH range (3-7). Additionally, the interactions of the halophilic archaeal strain Halobacterium noricense DSM 15987, a salt rock representative reference strain, with U(VI) at high ionic strength was investigated. After 48 h the cells were still alive at uranium concentrations up to 60 μM, which demonstrates that Halobacterium noricense can tolerate uranium concentrations up to this level. The formed uranium sorption species were examined with time-resolved laser-induced fluorescence spectroscopy (TRLFS). The results about the microbial communities present in potential host rocks for nuclear waste repositories and their interactions with radionuclides contribute to the safety assessment of a prospective nuclear waste repository.

  12. Interaction and transport of actinides in natural clay rock with consideration of humic substances and clay organics. Characterization and quantification of the influence of clay organics on the interaction and diffusion of uranium and americium in the clay. Joint project

    Bernhard, Gert [Helmholtz-Zentrum Dresden-Rossendorf e.V. (Germany). Inst. of Radiochemistry; Schmeide, Katja; Joseph, Claudia; Sachs, Susanne; Steudtner, Robin; Raditzky, Bianca; Guenther, Alix

    2011-07-01

    , was found to be endothermic and entropy-driven. In contrast, the complex stability constants determined for U(VI) humate complexation at 20 and 40 C are comparable, however, decrease at 60 C. For aqueous U(IV) citrate, succinate, mandelate and glycolate species stability constants were determined. These ligands, especially citrate, increase solubility and mobility of U(IV) in solution due to complexation. The U(VI) sorption onto crushed Opalinus Clay (OPA, Mont Terri, Switzerland) was studied in the absence and presence of HA or low molecular weight organic acids, in dependence on temperature and CO2 presence using OPA pore water as background electrolyte. Distribution coefficients (K{sub d}) were determined for the sorption of U(VI) and HA onto OPA with (0.0222 {+-} 0.0004) m{sup 3}/kg and (0.129 {+-} 0.006) m{sup 3}/kg, respectively. The U(VI) sorption is not influenced by HA ({<=}50 mg/L), however, decreased by low molecular weight organic acids ({>=} 1 x 10{sup -5} M), especially by citrate and tartrate. With increasing temperature, the U(VI) sorption increases both in the absence and in the presence of clay organics. The U(VI) diffusion in compacted OPA is not influenced by HA at 25 and 60 C. Predictions of the U(VI) diffusion show that an increase of the temperature to 60 C does not accelerate the migration of U(VI). With regard to uranium-containing waste, it is concluded that OPA is suitable as host rock for a future nuclear waste repository since OPA has a good retardation potential for U(VI). (orig.)

  13. Interaction and transport of actinides in natural clay rock with consideration of humic substances and clay organics. Characterization and quantification of the influence of clay organics on the interaction and diffusion of uranium and americium in the clay. Joint project

    Bernhard, Gert; Schmeide, Katja; Joseph, Claudia; Sachs, Susanne; Steudtner, Robin; Raditzky, Bianca; Guenther, Alix

    2011-01-01

    and entropy-driven. In contrast, the complex stability constants determined for U(VI) humate complexation at 20 and 40 C are comparable, however, decrease at 60 C. For aqueous U(IV) citrate, succinate, mandelate and glycolate species stability constants were determined. These ligands, especially citrate, increase solubility and mobility of U(IV) in solution due to complexation. The U(VI) sorption onto crushed Opalinus Clay (OPA, Mont Terri, Switzerland) was studied in the absence and presence of HA or low molecular weight organic acids, in dependence on temperature and CO2 presence using OPA pore water as background electrolyte. Distribution coefficients (K d ) were determined for the sorption of U(VI) and HA onto OPA with (0.0222 ± 0.0004) m 3 /kg and (0.129 ± 0.006) m 3 /kg, respectively. The U(VI) sorption is not influenced by HA (≤50 mg/L), however, decreased by low molecular weight organic acids (≥ 1 x 10 -5 M), especially by citrate and tartrate. With increasing temperature, the U(VI) sorption increases both in the absence and in the presence of clay organics. The U(VI) diffusion in compacted OPA is not influenced by HA at 25 and 60 C. Predictions of the U(VI) diffusion show that an increase of the temperature to 60 C does not accelerate the migration of U(VI). With regard to uranium-containing waste, it is concluded that OPA is suitable as host rock for a future nuclear waste repository since OPA has a good retardation potential for U(VI). (orig.)

  14. Basal Ottawa Limestone, Chattanooga Shale, Floyd Shale, Porters Creek Clay, and Yazoo Clay in parts of Alabama, Mississippi and Tennessee as potential host rocks for underground emplacement of waste

    Mellen, F.F.

    1976-01-01

    Impermeable rock units, preferably at least 500 feet thick and lying 1000 to 3000 feet below land surface, were sought in the region consisting roughly of the western 3 / 5 ths of Tennessee and the northern 3 / 5 ths of Alabama and Mississippi. All rock sequences, Cambrian through Eocene, were examined in varying detail, except the Cretaceous Selma Chalk and except the diapiric salt. These rocks were studied for their relative impermeable homogeneity, their continuity, their background of structural and seismic stability and their hydrologic associations. The Central Mississippi Ridge of north-central Mississippi is overlain by a long-stable mass of Porters Creek Clay 500-700 feet thick, in an area roughly 50-60 miles wide and about 150 miles long. The Yazoo Clay, where best developed in the west-central and southwest part of Mississippi, is in the 400-500 foot thickness range, but locally exceeds 500 feet. The entire area mapped is underlain by the Louann Salt which has produced many deep-seated salt domes and numerous piercement salt domes. Salt flow has complicated shallow structural geology throughout that area. The Chattanooga Shale rarely exceeds 60 feet in thickness in the region studied and is generally much thinner and is absent in many places. In the lower part of the Middle Ordovician (Ottawa Megagroup), the Murphreesboro and associated dense limestones appear to offer a potential disposal unit 250-400 feet thick, having the advantages of rock competency and freedom from association with prolific aquifers in the overburden or beneath. Other less conspicuous stratigraphic units are reviewed

  15. Numerical analysis of thermo-hydro-mechanical (THM) processes in the clay based material

    Wang, Xuerui

    2016-10-06

    conductivity on the degree of water saturation, the dependency of the thermal effects on the water retention behaviour, and the dependency of the effects of the pore pressure variation on the permeability and the anisotropic swelling/shrinkage behaviour have been intensively analysed and the corresponding numerical models to consider those coupling effects have been developed. The developed numerical model has been applied to simulate the laboratory and in situ heating experiments on the bentonite and clay rock at different scales. Firstly the laboratory heating experiment on Callovo-Oxfordian Clay (COX) and the laboratory long-term heating and hydration experiment on MX80 pellets were simulated. Based on the knowledge from the numerical analysis of the laboratory experiments, a 1:2 scale in situ heating experiment of an integrated system of the bentonite engineered barrier system (EBS) in the Opalinus Clay host rock was simulated. All the relevant operation phases were considered in the modelling. Besides, the modelling was extended to 50 years after the heat shut-down with the aim of predicting the long-term behaviours. Additionally, variation calculations were carried out to investigate the effects of the storage capacity of the Opalinus Clay on the thermally induced hydraulic response. In the long-term modelling, the effects of different saturated water permeabilities of buffer material on the resaturation process were analysed. Based on the current researches and model developments, the observed THM behaviours of the bentonite buffer and the clay rock, that is, the measured evolution of temperature, pore pressure, humidity, swelling pressure, and so on in the laboratory and in situ experiments can be reproduced and interpreted well. It is proved that by using both a non-isothermal multiphase flow model and a non-isothermal Richards flow model combined with the corresponding thermal and mechanical models, the major THM behaviours can be captured. It is validated that the

  16. Numerical analysis of thermo-hydro-mechanical (THM) processes in the clay based material

    Wang, Xuerui

    2016-01-01

    conductivity on the degree of water saturation, the dependency of the thermal effects on the water retention behaviour, and the dependency of the effects of the pore pressure variation on the permeability and the anisotropic swelling/shrinkage behaviour have been intensively analysed and the corresponding numerical models to consider those coupling effects have been developed. The developed numerical model has been applied to simulate the laboratory and in situ heating experiments on the bentonite and clay rock at different scales. Firstly the laboratory heating experiment on Callovo-Oxfordian Clay (COX) and the laboratory long-term heating and hydration experiment on MX80 pellets were simulated. Based on the knowledge from the numerical analysis of the laboratory experiments, a 1:2 scale in situ heating experiment of an integrated system of the bentonite engineered barrier system (EBS) in the Opalinus Clay host rock was simulated. All the relevant operation phases were considered in the modelling. Besides, the modelling was extended to 50 years after the heat shut-down with the aim of predicting the long-term behaviours. Additionally, variation calculations were carried out to investigate the effects of the storage capacity of the Opalinus Clay on the thermally induced hydraulic response. In the long-term modelling, the effects of different saturated water permeabilities of buffer material on the resaturation process were analysed. Based on the current researches and model developments, the observed THM behaviours of the bentonite buffer and the clay rock, that is, the measured evolution of temperature, pore pressure, humidity, swelling pressure, and so on in the laboratory and in situ experiments can be reproduced and interpreted well. It is proved that by using both a non-isothermal multiphase flow model and a non-isothermal Richards flow model combined with the corresponding thermal and mechanical models, the major THM behaviours can be captured. It is validated that the

  17. clay nanocomposites

    The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

  18. Constitutive relationships for elastic deformation of clay rock: Data Analysis

    Liu, H.H.; Rutqvist, J.; Birkholzer, J.T.

    2011-01-01

    Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate our theoretical development, we analyze uniaxial test data for core samples of Opalinus clay and laboratory measurements of single fractures within macro-cracked Callovo-Oxfordian argillite samples subject to both confinement and water reduced swelling. The results from this evaluation indicate that our constitutive relationships can adequately represent the data and explain the related observations.

  19. Constitutive relationships for elastic deformation of clay rock: Data Analysis

    Liu, H.H.; Rutqvist, J.; Birkholzer, J.T.

    2011-04-15

    Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate our theoretical development, we analyze uniaxial test data for core samples of Opalinus clay and laboratory measurements of single fractures within macro-cracked Callovo-Oxfordian argillite samples subject to both confinement and water reduced swelling. The results from this evaluation indicate that our constitutive relationships can adequately represent the data and explain the related observations.

  20. JOINTS AND SYN-SEDIMENTARY FAULTS NETWORKS IN MARINE CLAYS AND MUDSTONES. Importance for Radwaste storage

    Arnould, M.

    2009-12-01

    There is a number of marine clays, mudstones, marls, 100 to 200 m thick, showing smectites, mixed layers illite/smectite, with a small percentage of organic matter and sulphides with a variable clay, silt, and carbonate content. I published (Arnould , 2006) examples from Lower Cambrian to Miocene in age and from the Baltic shore to Spain in Europe. Observations were made mostly in quarries and pits down to more than 40 m and in underground research laboratories (URL). Only visible on fresh cuts amongst a variety of fissures there is always a network of joints. Schematically one family is the bedding (horizontal) the two others are normal to the bedding and orthogonal between them. The orientations of vertical joints are different from the orientations of pits and quarries’s walls. The networks are intrinsic. It was first well described by Skempton & al (1969) in Eocene London Clay. Joints are matt in texture, clean, without filling or cement. The order of magnitude of their linear dimensions is decimeter to meter. It is necessary to start from the original sediment: mud. Deposited in flakes mud has a bee’s nest microscopic structure. Each nest is full of water. Hence mud may have a water content up to 300%, reported to its dry weight. Paradoxically mud is impervious. As proposed by Cosgrove (2001) progressive but discontinuous hydraulic fracturing could be the origin of vertical joints, with drainage upwards and compaction of the sediment. Geological observations show that ioints are formed during the sedimentation process. There is also a world literature concluding at the necessary early fracturing of mudstones and marls hosts of sand dykes. Very few faults are identified in field observations and on exploration logs. But it is obvious that drainage and compaction of mud over thousands square kilometers induced differential settlements with many syn-sedimentary non tectonic faults constituting another discontinuity network. These faults inside the same

  1. Technetium migration in natural clays; Migration von Technetium in natuerlichem Tongestein

    Luebke, Maria

    2015-10-01

    The present work was performed within the joint research project ''Retention of repository relevant radionuclides in argillaceous rocks and saline systems'' (contract no.: 02E10981), funded by the Federal Ministry for Economic Affairs and Energy (BMWi). The aim was to obtain first insights into the interaction of the long-lived fission product technetium and natural clay with regard to a repository for high-level nuclear waste. For this purpose Opalinus Clay from Mont Terri (northern Switzerland) was used as a reference material. The nuclide technetium-99 will contribute to the radiotoxicity of spent nuclear fuel for more than thousand years due to its long half-live. In case of a leakage of the storage vessels, the geochemistry of technetium is determined by its oxidation state, at which only the oxidation states +IV and +VII are relevant. Because of the high solubility and low affinity to sorption on surfaces of minerals, Tc(VII) is considered to be very mobile and thus the most hazardous species. The focuses of this study therefore are diffusion experiments with this mobile species and investigations of the effect of ferrous iron on the mobility and speciation of technetium.rnThe interaction of technetium and Opalinus Clay was studied in sorption and diffusion experiments varying several parameters (pH value, addition of reducing agents, effect of oxygen, diffusion pathways). In the course of this study spatially resolved investigations of the speciation have been performed on Opalinus Clay thin sections and bore cores for the first time. In addition to the speciation, further information regarding elemental distributions and crystalline phases near technetium enrichments were obtained. Supplementary investigations of powder samples allowed determining the molecular structure of technetium on the clay surface.rnBoth the combination of sorption experiments with spectroscopic investigations and the diffusion experiment exhibit a reduction of Tc

  2. Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

    Tournassat, Christophe, E-mail: c.tournassat@brgm.fr [BRGM, French Geological Survey, Orleans (France); Alt-Epping, Peter [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland); Gaucher, Eric C. [BRGM, French Geological Survey, Orleans (France); Gimmi, Thomas [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland)] [Laboratory for Waste Management, Paul Scherrer Institut, Villigen (Switzerland); Leupin, Olivier X. [NAGRA, CH-5430 Wettingen (Switzerland); Wersin, Paul [Gruner Ltd., CH-4020 Basel (Switzerland)

    2011-06-15

    Highlights: > Reactive transport modelling was used to simulate simultaneously solute transport, thermodynamic reactions, ion exchange and biodegradation during an in-situ experiment in a clay-rock formation. > Opalinus clay formation has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. > Buffering capacity is mainly attributed to the carbonate system and to the reactivity of clay surfaces (cation exchange, pH buffering). - Abstract: Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C, dissolved inorganic C and SO{sub 4} concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of

  3. Self-sealing of fractures in argillaceous formations - Evidence, mechanisms and implications for performance assesment (an NEA Clay Club project)

    Bock, H.; Dehandschutter, B.; Martin, C.D.; Mazurek, M.; Haller, A. de; Skoczylas, F.; Davy, C.

    2010-01-01

    Document available in extended abstract form only. After some earlier attempts dating back to the year 1999, the Self-Sealing Project of the Clay Club of the NEA/OECD was re-launched in 2007 and recently completed with the publication of NEA monograph No. 6184 (Bock et al., 2010). The project aimed at providing an overview and synthesis of the current understanding of, and conceptual approaches to, the processes that lead to self-sealing of natural and man-induced fractures in argillaceous formations at typical repository depths. The term 'self-sealing' relates to a phenomenon that fractured argillaceous formations tend to become, with the passage of time, less conductive to groundwater and finally hydraulically insignificant. It directly addresses the long-term functionality of the host rock as a migration barrier to radio-nuclides and it is often considered as one of the decisive factors favouring the choice of argillaceous formations as host rocks for deep disposals. In its outcome the project has significantly consolidated the evidence on self-sealing in argillaceous formations. It reconfirmed that self-sealing is a common phenomenon in a wide variety of argillaceous formations which are currently considered in context with deep geological repositories; from plastic clays (Boom Clay in the HADES URF) to moderately indurated clays (Opalinus Clay at Mont Terri and Callovo- Oxfordian argillites at the Meuse-Haute Marne URL). One of the most compelling evidence stems from the fact that self-sealing is observed over a large spread of scales in terms of length and time: At the millimetre to metre scale in laboratory testing, at the repository scale (10 m to 100 m range) in URL field tests and at the kilometre scale in geologic and geotechnical analogues such as traffic tunnels and hydrocarbon reservoirs. Over geological time scales, it is, for example, evidenced in the existence of hydraulically and geochemically inactive geological faults, in the existence

  4. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    Moll, Henry [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biogeochemistry; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). HZDR Young Investigator Group; Bok, Frank [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    The time-dependent {sup 242}Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  5. Cementitious Near-Field Sorption Data Base for Performance Assessment of an ILW Repository in Opalinus Clay

    Wieland, E.; Van Loon, L. R

    2003-08-01

    The present report describes a cement sorption database (SDB) for the safety-relevant radionuclides to be disposed of in the planned Swiss repository for long-lived intermediate-level radioactive wastes (ILW). This report is an update on earlier SDBs, which were compiled for the cementitious near field of a repository for low- and intermediate-level radioactive wastes (L/ILW) by BRADBURY + SAROTT (1995) and BRADBURY + VAN LOON (1998). The radionuclide inventories are determined by the waste streams to be disposed of in the ILW repository. A list of the safety-relevant radionuclides was provided based on the currently available information on ILW inventories. The compositions of the cement porewaters in the near fields of the L/ILW and ILW repositories, which had been calculated using well-established codes for modelling cement degradation, were compared to identify any differences in the near-field conditions and to assess their influence on radionuclide sorption. Sorption values were selected based on the previously reported SDBs for the near field of the L/ILW repository. Sorption values were revised if new information and/or data were available which allowed changes to or re-appraisals of the data to be made. The sorption values recommended in this report were either selected on the basis of data from in-house experimental studies or from literature data. For some key radioelements, i.e., Cs(l), Sr(II), Ni(II), Eu(lll), Th(IV) and Sn(IV), new data were available from in-house measurements. These elements had been selected for experimental studies due to their relevance to safety assessment and/or their importance as appropriate chemical analogues. Degradation products of bitumen and cellulose, concrete admixtures and cement-derived near-field colloids were taken into account as the main potential perturbations, which could reduce radionuclide sorption in the near field. Possible impacts of the perturbing factors on radionuclide mobility were considered and quantified in terms of sorption reduction factors. (author)

  6. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    Moll, Henry; Cherkouk, Andrea; Bok, Frank

    2017-01-01

    The time-dependent "2"4"2Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  7. Chemical buffering capacity of clay rock

    Beaucaire, C.; Pearson, F.J.; Gautschi, A.

    2004-01-01

    The long-term performance of a nuclear waste repository is strongly dependent on the chemical properties of the host rock. The host rock establishes the chemical environment that determines such important performance attributes as radionuclide solubilities from the waste and the transport rates from the repository to the accessible environment. Clay-rich rocks are especially favourable host rocks because they provide a strong buffering capacity to resist chemical changes prompted either internally, by reactions of the waste itself and emplacement materials, or externally, by changes in the hydrologic systems surrounding the host rock. This paper will focus on three aspects of the stability of clay-rich host rocks: their ability to provide pCO 2 and redox buffering, and to resist chemical changes imposed by changes in regional hydrology and hydro-chemistry. (authors)

  8. Biogeochemical processes in a clay formation in situ experiment: Part B - Results from overcoring and evidence of strong buffering by the rock formation

    Koroleva, M. [Institute of Geological Sciences, University of Bern, Baltzerstrasse 3, CH-3012 Bern (Switzerland); Lerouge, C. [BRGM, French Geological Survey, 3 Avenue Claude Guillemin, B.P. 36009, 45060 Orleans Cedex 2 (France); Maeder, U., E-mail: urs.maeder@geo.unibe.ch [Institute of Geological Sciences, University of Bern, Baltzerstrasse 3, CH-3012 Bern (Switzerland); Claret, F.; Gaucher, E. [BRGM, French Geological Survey, 3 Avenue Claude Guillemin, B.P. 36009, 45060 Orleans Cedex 2 (France)

    2011-06-15

    Highlights: > A 5-year in situ porewater chemistry experiment in Opalinus Clay was overcored and examined. > A microbial perturbation induced sulfate reduction, pH decrease and alkalinity / P{sub CO2} increase. > Changes to mineralogy, isotopic composition and bulk properties could not be detected. > Precipitation of Fe-sulfides and carbonate occurred at the interface of the test interval. > The chemical perturbation was effectively buffered by the claystone's large capacity. - Abstract: An in situ Porewater Chemistry (PC) experiment in the Opalinus Clay formation was carried out at the Mont Terri underground rock laboratory (Jura Mountains, Switzerland) for a period of 5 a. A traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed-off borehole to achieve diffusive equilibration. An unwanted microbial perturbation changed the water composition, characterized by reduction of SO{sub 4} combined with increasing sulfide, increasing alkalinity, decreasing pH and increasing P(CO{sub 2}). In contrast, the main cations (Na, Ca, Mg) remained remarkably constant during the experiment, thus indicating the strong buffering of the formation via cation and proton exchange as well as carbonate dissolution/precipitation reactions. After 5 a, the 4.5 m long vertical test interval was overcored and Opalinus Clay samples were analyzed along ca. 15 cm long radial profiles. The analytical investigations included mineralogy (XRD, SEM-EDX), bulk parameters (water content, density, C, S), cation exchange capacity and occupancy, aqueous leachates for Cl{sup -}, Br{sup -}, SO{sub 4}{sup 2-} and water and carbonate stable isotopes. Emphasis was put on best sample preparation and conservation techniques. Results show that the distribution of non-reactive tracers (Br{sup -} and {sup 2}H) follows the expected out/in-diffusion profiles compatible with the time-dependent boundary conditions in the test interval of the

  9. A preliminary study on titanium-clay interactions

    Wersin, P.; Grolimund, D.; Kumpulainen, S.; Brendle, J.; Snellman, M.

    2010-01-01

    bentonite, Opalinus Clay, Illite du Puy) were characterized by XAS. Preliminary results can be summarized as: (1) Natural clay materials contain significant but variable amounts of Ti. The standard purification procedure for bentonites to remove accessories does not or only barely removes Ti. (2) The Ti in the natural clays materials Rokle bentonite, Opalinus Clay, Illite du Puy occurs as microcrystalline TiO 2 (presumably as anatase). On the other hand, the Ti spectra in MX-80 suggest the presence of structural Ti in the smectite, but the evidence is not conclusive so far. (3) The exposure of purified MX-80 to titanium powder at room temperature within a period of five months did not lead to measurable additional Ti in the clay. This was even true for samples exposed to acidic or alkaline conditions where corrosion rates and solubility of Ti are known to be higher. Thereof, the following preliminary conclusions can be drawn: - The Ti content in natural bentonites is concentrated mainly in the so-called clay fraction. Ti occurs therein either as separate small TiO 2 particles (Rokle, Opalinus Clay, Illite du Puy) or as structural Ti. As indicated by the study of Karnland et al. (2006), the properties of natural bentonites are not affected by the presence of Ti. In that study, the bulk properties (swelling pressure, hydraulic conductivity) were very similar for the different bentonites containing variable Ti content, ranging from 0.1 to 4.8 weight % TiO 2 in the purified clay fractions. The transfer rates of Ti from the metallic source, even in reactive powder form, to the clay are very low and no enrichment above background concentrations after several months could be observed. In order to obtain measurable effects, both the corrosion process must be increased and the background concentration must be reduced. Tests with Ti-free clay material at increased temperature are still ongoing and will hopefully enable identification of reacted Ti species. (authors)

  10. Clay Mineralogy of Coal-Hosted Nb-Zr-REE-Ga Mineralized Beds from Late Permian Strata, Eastern Yunnan, SW China: Implications for Paleotemperature and Origin of the Micro-Quartz

    Lixin Zhao

    2016-05-01

    Full Text Available The clay mineralogy of pyroclastic Nb(Ta-Zr(Hf-REE-Ga mineralization in Late Permian coal-bearing strata from eastern Yunnan Province; southwest China was investigated in this study. Samples from XW and LK drill holes in this area were analyzed using XRD (X-ray diffraction and SEM (scanning electronic microscope. Results show that clay minerals in the Nb-Zr-REE-Ga mineralized samples are composed of mixed layer illite/smectite (I/S; kaolinite and berthierine. I/S is the major component among the clay assemblages. The source volcanic ashes controlled the modes of occurrence of the clay minerals. Volcanic ash-originated kaolinite and berthierine occur as vermicular and angular particles, respectively. I/S is confined to the matrix and is derived from illitization of smectite which was derived from the original volcanic ashes. Other types of clay minerals including I/S and berthierine precipitated from hydrothermal solutions were found within plant cells; and coexisting with angular berthierine and vermicular kaolinite. Inferred from the fact that most of the I/S is R1 ordered with one case of the R3 I/S; the paleo-diagenetic temperature could be up to 180 °C but mostly 100–160 °C. The micro-crystalline quartz grains (<10 µm closely associated with I/S were observed under SEM and were most likely the product of desiliconization during illitization of smectite.

  11. Common clay and shale

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

  12. Clay Portrait Boxes

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  13. Columns in Clay

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  14. Proceedings of the NEA Clay Club Workshop on Clay characterisation from nanoscopic to microscopic resolution

    2013-01-01

    A wide spectrum of argillaceous media are being considered in Nuclear Energy Agency (NEA) member countries as potential host rocks for the final, safe disposal of radioactive waste, and/or as major constituent of repository systems in which wastes will be emplaced. In this context, the NEA established the Working Group on the 'Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations' in 1990, informally known as the 'Clay Club'. The Clay Club examines various argillaceous rocks that are being considered for the underground disposal of radioactive waste, ranging from soft clays to indurated shales. Very generally speaking, these clay rocks are composed of fine-grained minerals showing pore sizes from < 2 nm (micropores) up to > 50 nm (macro-pores). The water flow, solute transport and mechanical properties are largely determined by this microstructure, the spatial arrangement of the minerals and the chemical pore water composition. Examples include anion accessible ('geochemical') porosity and macroscopic membrane effects (chemical osmosis, hyper-filtration), geomechanical properties and the characteristics of two-phase flow properties (relevant for gas transport). At the current level of knowledge, there is a strong need to improve the nanoscale description of the phenomena observed at a more macroscopic scale. However, based on the scale of individual clay-minerals and pore sizes, for most of the imaging techniques this resolution is a clear challenge. The workshop, hosted by the Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT) in the Akademiehotel Karlsruhe (Germany) from 6 to 8 September 2011, was intended to give, inter alia, a discussion platform on: - The current state-of-the-art of different spectro-microscopic methods - New developments addressing the above mentioned knowledge gaps in clays. - The perception of the interplay between geometry

  15. Characterization of clay minerals

    Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

    2002-01-01

    The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

  16. Thixotropic Properties of Latvian Clays

    Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

    2015-01-01

    This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

  17. First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

    Behrends, T.; Veen, I. van der; Hoving, A.; Griffioen, J.

    2016-01-01

    The Rupel Clay member in the Netherlands largely corresponds to the Boom Formation in Belgium, and this marine, clay-rich deposit is a potential candidate to host radioactive waste disposal facilities. Prediction of the speciation of radionuclides in Rupel Clay pore water and their retardation by

  18. Hydroxyapatite clay for gap filling and adequate bone ingrowth.

    Maruyama, M; Terayama, K; Ito, M; Takei, T; Kitagawa, E

    1995-03-01

    In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

  19. On the thermal behaviour of Boom clay

    Delage, P.; Cui Yu Jun; Sultan, N.

    2004-01-01

    When temperature is increased, the various phenomena that occur in a saturated natural potential host clay for nuclear waste disposal (Boom clay from SCK-CEN in Mol, Belgium) were experimentally investigated in a temperature controlled high stress triaxial cell. Firstly, the pore pressure build-up due to the difference in thermal dilation of both water and minerals was investigated through thermal consolidation tests. Interesting information was obtained about the dissipation of thermally induced pore pressure in Boom clay, based on the standard Terzaghi consolidation theory. Secondly, the volume change behaviour in drained conditions (i.e. under a very slow temperature increase) confirmed that the clay overconsolidation ratio (OCR) controlled the nature of the volume changes. Whereas overconsolidated soils use to dilate as any material when temperature is elevated, normally consolidated soils present a decrease in volume, which is less common. The principles of a coupled thermo-elasto-plastic model that was specifically developed to model this particular behaviour are finally presented. Obviously, it appears necessary to account in detail for these thermal phenomena in order to properly understand the response of the geological barrier in the near field once nuclear waste has been stored. (orig.)

  20. In situ determination of anisotropic permeability of clay

    Shao, H.; Soennke, J.; Morel, J.; Krug, S.

    2010-01-01

    in clay stone is generally considered to have a depth of approximately 2 metres. Therefore, a 3-m borehole can also be used for both objects. Ail boreholes are drilled by using dry air technique and oriented parallel to the bedding plane, so that the permeability parallel and perpendicular to the bedding plane can be tested only by turning the 'slot'. Hydraulic tests using gas as test medium are carried out immediately after the drilling of the holes. For evaluation of the measured data, the finite element program RockFlow has been used. The packer 'slot' with a width of 1 cm can also be simulated in the numerical model. Most of the measurements show a clear hydraulic anisotropy due to the bedding structure. As summary, following statements can be made: - Hydraulic anisotropy of clay medium can be determined using the developed 'slot packer' system with orientated applications. - The anisotropic ratio of the Opalinus Clay at Mont Terri (permeability parallel to the bedding/permeability perpendicular to the bedding) may be evaluated up to eight times to one order of magnitude. - Fractures in the excavation damaged zone around the underground opening in clay formations can be identified and especially the orientations of the fractures can be determined using the 'slot packer'. - The fracture permeability has a significant importance for the hydraulic characterisation of the near field. A double packer is sufficient to determine the permeability for this purpose. This tool can also be applied in fractured rock (e.g. granite) to determine the fracture orientation. (authors)

  1. Clay and concrete brick

    Dlamini, MN

    2014-03-01

    Full Text Available Brick is one of the most used and versatile building materials in use today. Bricks can be defined as modular units connected by mortar in the formation of a building system or product. Commonly the word brick is used to refer to clay bricks, which...

  2. Clay matrix voltammetry

    Perdicakis, Michel

    2012-01-01

    Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

  3. Physical Properties of Latvian Clays

    Jurgelāne, I; Stepanova, V; Ločs, J; Mālers, J; Bērziņa-Cimdiņa, L

    2012-01-01

    Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

  4. Gonadossomatic relation and reproductive strategy of Brycon opalinus (Cuvier, 1819 in the Serra do Mar State Park - Núcleo Santa Virgínia, Atlantic Forest, Brazil

    LM Gomiero

    Full Text Available The objective of this study was to analyze the gonadossomatic relation of males and females of Brycon opalinus (the Pirapitinga do Sul in the Serra do Mar State Park-Núcleo Santa Virgínia. The study area included three rivers: Paraibuna, Ipiranga, and Grande. From the gonadossomatic relation, it was possible to determine the reproductive season and strategy of this species. The gonadossomatic relation was high throughout the year for both males and females. Sperm competition and dilution of the ejaculate in the spawning locations favored substantial development of the testicles. The sex ratio of Brycon opalinus was always in favor of females. The existence of sexual dimorphism in this species was confirmed from the larger size of the females.

  5. Clay Animals and Their Habitats

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  6. Clay membrane made of natural high plasticity clay

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...

  7. Clay membrane made of natural high plasticity clay:

    Foged, Niels; Baumann, Jens

    1999-01-01

    Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

  8. Clay club catalogue of characteristics of argillaceous rocks

    2005-01-01

    The OECD/NEA Working Group on the Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations, namely the Clay Club, examines the various argillaceous rocks that are being considered for the deep geological disposal of radioactive waste, i.e. from plastic, soft, poorly indurated clays to brittle, hard mud-stones or shales. The Clay Club considered it necessary and timely to provide a catalogue to gather in a structured way the key geo-scientific characteristics of the various argillaceous formations that are - or were - studied in NEA member countries with regard to radioactive waste disposal. The present catalogue represents the outcomes of this Clay Club initiative. (author)

  9. Geophysical monitoring of the EDZ during a gallery excavation in the Opalinus clay of the Mont Terri URL: design and principles of specific in situ experimental setups

    Gibert, D.; Maineult, A.; Kergosien, B.; Le Gonidec, Y.; Nicollin, F.; Sarout, J.; Wassermann, J.

    2012-01-01

    Document available in extended abstract form only. At the Mont Terri Underground Rock Laboratory, the gallery Ga08 was excavated in August 2008 to join the end-face of the pre-existing gallery Ga04. The Excavation Damaged Zone (EDZ) induced during the gallery construction was monitored from the instrumented face of Ga04. The EZ-G08 experiments required original acquisition setups, specifically designed to be installed in small boreholes and to ensure long term measurements. Different geophysical methods have been experimented for the EZ-G08 project and specific design of the experiments were required in order to coordinate multiple and simultaneous acquisitions, including acoustic emission (AE) acquisition setup (16 acoustic receivers), manufacturing of a combined electrical (256 electrodes) and acoustic tomography setup (64 receivers) to be introduced in horizontal boreholes with small diameters (56 mm), design of an acoustic source, design and manufacturing of a combined electrical tomography (64 lead electrodes) and self-potential measurements (64 un-polarizable electrodes). Other arrays of electrodes have also been placed at the end-face of Ga04 (715 inox electrodes and an array of 16 un-polarizable electrodes). The self-potential (SP) monitoring took place in the borehole BEZ-G5 equipped in mid- February 2008 with a specific device on which custom-made electrodes were fixed. To avoid polarisation effect and guaranty a satisfactorily signal-to-noise ratio, SP was measured with 64 un-polarizable electrodes, with an offset of 15 cm made of a metallic wire in chemical equilibrium with a surrounding solution containing a salt of the same metal. The electrical contact between the solution and the natural medium is ensured by a porous material. The electrodes were mounted upward on a half-cylinder fixed onto an inflatable pipe and introduced in BEZ-G5. The internal pipe was inflated to ensure a good electrical contact between the electrodes and the borehole wall. The combined electrical and seismic tomography setup consists in four arrays inserted into each small-diameter boreholes BEZ-G12:15. Specifically designed holding poles were made of two half cylinders with an inflatable membrane located between them: one half cylinder to hold the electrodes, while the other half was designed to hold the acoustic receivers. No interactions were observed between these two types of equipment during the experiment. The purpose of the inflatable membrane, pressurized with air at 1.4 bar, was to push the sensors against the borehole wall and to ensure a good coupling between each set of sensors and the borehole wall. On each holding pole, of 3.2 m in length, 16 piezo-ceramics with an offset of 20 cm were fixed on one side and on the other side, 64 lead electrodes were fixed with an offset of 5 cm. In order to measure acoustic surveys inside the rock mass, an active source was designed to be introduced in BEZ-G5: the omnidirectional source allowed to sound the medium with different travel paths to study the anisotropic structure of the rock. More than one month of measurements took place in boreholes BEZ-G12:15, both for the electrical and the acoustic acquisition, which produced a very large data base. (authors)

  10. A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

    Graham Edward

    2006-04-01

    Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

  11. Shaft sealing concepts for high-level radioactive waste repositories based on the host-rock options rock salt and clay stone; Schachtverschlusskonzepte fuer zukuenftige Endlager fuer hochradioaktive Abfaelle fuer die Wirtsgesteinsoptionen Steinsalz und Ton

    Kudla, Wolfram; Gruner, Matthias [TU Bergakademie Freiberg (Germany). Inst. fuer Erdbau und Spezialtiefbau; Herold, Philipp; Jobmann, Michael [DBE Technology GmbH, Peine (Germany)

    2015-07-01

    Unlike the shaft barriers used for the dry preservation of former mine workings and underground storage sites, shaft seals designed for radioactive-waste repositories must also fulfil additional requirements associated with the design diversity of the sealing system. This diversity makes use of the simple redundancy principle in order to prevent the proliferation of defects. In practice this means combining several sealing elements made from different materials or from materials with different properties. The R and D project, Shaft sealing systems for final repositories for high-level radioactive waste (ELSA) - phase 2: concept design for shaft seals and testing of the functional elements of shaft seals', which was funded by the Federal Ministry for Economic Affairs and Energy (BMWi), set out to investigate potential sealing elements for the two host-rock options rock salt and mudstone. This paper combines the text that the authors presented at the First International Freiberg Shaft Colloquium held at the Freiberg University of Mining and Technology on 01.10.2014 with a presentation on the sealing elements that were investigated as part of the R and D project.

  12. The general situation of clay site for high-level waste geological disposal repository

    Wang Changxuan; Liu Xiaodong; Liu Pinghui

    2008-01-01

    Host medium is vitally important for safety of high-level radiaoactive waste (HLW) geological disposal. Clay, as host media of geological repository of HLW, has received greater attention for its inherent advantages. This paper summarizes IAEA and OECD/NEA's some safety guides on site selection and briefly introduces the process of the site selection, their studies and the characteristics of the clay formations in Switz-erland, France and Belgian. Based on these analyses, some suggestions are made to China's HLW repository clay site selection. (authors)

  13. Research of Deformation of Clay Soil Mixtures Mixtures

    Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

    2014-01-01

    The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

  14. Retention of contaminants Cd and Hg adsorbed and intercalated in aluminosilicate clays: A first principles study

    Crasto de Lima, F. D.; Miwa, R. H.; Miranda, Caetano R.

    2017-11-01

    Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ˜20 and ˜130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays.

  15. Creep in buffer clay

    Pusch, R.; Adey, R.

    1999-12-01

    The study involved characterization of the microstructural arrangement and molecular forcefields in the buffer clay for getting a basis for selecting suitable creep models. It is concluded that the number of particles and wide range of the particle bond spectrum require that stochastical mechanics and thermodynamics will be considered and they are basic to the creep model proposed for predicting creep settlement of the canisters. The influence of the stress level on creep strain of MX-80 clay is not well known but for the buffer creep is approximately proportional to stress. Theoretical considerations suggest a moderate impact for temperatures up to 90 deg C and this is supported by model experiments. It is believed that the assumption of strain being proportional to temperature is conservative. The general performance of the stochastic model can be illustrated in principle by use of visco-elastic rheological models implying a time-related increase in viscosity. The shear-induced creep settlement under constant volume conditions calculated by using the proposed creep model is on the order of 1 mm in ten thousand years and up to a couple of millimeters in one million years. It is much smaller than the consolidation settlement, which is believed to be on the order of 10 mm. The general conclusion is that creep settlement of the canisters is very small and of no significance to the integrity of the buffer itself or of the canisters

  16. Euroclay 95. Clays and clay materials sciences. Book of abstracts

    Elsen, A.; Grobet, P.; Keung, M.; Leeman, H.; Schoonheydt, R.; Toufar, H.

    1995-01-01

    The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

  17. Euroclay 95. Clays and clay materials sciences. Book of abstracts

    Elsen, A; Grobet, P; Keung, M; Leeman, H; Schoonheydt, R; Toufar, H [eds.

    1995-08-20

    The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY `95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately.

  18. Enzymes activities involving bacterial cytochromes incorporated in clays

    Lojou, E.; Giudici-Orticoni, M.Th.; Bianco, P.

    2005-01-01

    With the development of bio electrochemistry, researches appeared on the enzymes immobilization at the surface of electrodes for the realization of bioreactors and bio sensors. One of the main challenges is the development of host matrix able to immobilize the protein material preserving its integrity. In this framework the authors developed graphite electrodes modified by clay films. These electrodes are examined for two enzyme reactions involving proteins of sulfate-reduction bacteria. Then in the framework of the hydrogen biological production and bioreactors for the environmental pollution de-pollution, the electrochemical behavior of the cytochrome c3 in two different clays deposed at the electrode is examined

  19. Influence of clay mineralogy on clay based ceramic products

    Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

    1996-01-01

    Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

  20. Heat production / host rock compatibility; Waermeentwicklung / Gesteinsvertraeglichkeit

    Meleshyn, A.; Weyand, T.; Bracke, G.; Kull, H.; Wieczorek, K.

    2016-05-15

    For the final high-level radioactive waste repository potential host rock formations are either rock salt or clays (Kristallin). Heat generating waste (decay heat of the radioactive materials) can be absorbed by the host rock. The effect of temperature increase on the thermal conductivity, the thermal expansion and the mechanical properties of salt, Kristallin, clays and argilliferous geotechnical barriers are described. Further issues of the report are the mineralogical behavior, phase transformations, hydrochemistry, microbial processes, gas formation, thermochemical processes and gas ingress. Recommendations for further research are summarized.

  1. Encapsulation of Clay Platelets inside Latex Particles

    Voorn, D.J.; Ming, W.; Herk, van A.M.; Fernando, R.H.; Sung, Li-Piin

    2009-01-01

    We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of

  2. Thixotropic Properties of Latvian Illite Containing Clays

    Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

    2015-01-01

    Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

  3. Viscosity and Plasticity of Latvian Illite Clays

    Jurgelāne, I; Vecstaudža, J; Stepanova, V; Mālers, J; Bērziņa-Cimdiņa, L

    2012-01-01

    Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

  4. Evaluation of Used Fuel Disposition in Clay-Bearing Rock

    Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weck, Philippe F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hammond, Glenn Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kuhlman, Kristopher L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, James [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cruse, Terry [Argonne National Lab. (ANL), Argonne, IL (United States); Ebert, William L. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-04

    Deep geological disposal of nuclear waste in clay/shale/argillaceous rock formations has received much consideration given its desirable attributes such as isolation properties (low permeability), geochemically reduced conditions, slow diffusion, sorbtive mineralogy, and geologically widespread (Jové Colón et al., 2014). There is a wealth of gained scientific expertise on the behavior of clay/shale/ argillaceous rock given its focus in international nuclear waste repository programs that includes underground research laboratories (URLs) in Switzerland, France, Belgium, and Japan. Jové Colón et al. (2014) have described some of these investigative efforts in clay rock ranging from site characterization to research on the engineered barrier system (EBS). Evaluations of disposal options that include nuclear waste disposition in clay/shale/argillaceous rock have determined that this host media can accommodate a wide range of waste types. R&D work within the Used Fuel Disposition Campaign (UFDC) assessing thermal effects and fluid-mineral interactions for the disposition of heat-generating waste have so far demonstrated the feasibility for the EBS and clay host rock to withstand high thermal loads. This report represents the continuation of disposal R&D efforts on the advancement and refinement of coupled Thermal-Hydrological-Mechanical-Chemical (THMC), hydrothermal experiments on clay interactions, used fuel degradation (source term), and thermodynamic modeling and database development. The development and implementation of a clay/shale/argillite reference case described in Jové Colón et al. (2014) for FY15 will be documented in another report (Mariner et al. 2015) – only a brief description will be given here. This clay reference case implementation is the result of integration efforts between the GDSA PA and disposal in argillite work packages. The assessment of sacrificial zones in the EBS is being addressed through experimental work along with 1D reactive

  5. Strength Properties of Aalborg Clay

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    glacial time are characterised by the absence of this mussel. These deposits are named Aalborg Clay and Aalborg Sand. In the city of Aalborg, a fill layer superposes Aalborg Clay. This layer is at some places found to be 6m thick. This fill layer does not provide sufficient bearing capacity, which has...... resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...

  6. Use of swelling clays to reduce permeability and its potential application to nuclear waste repository sealing

    Moore, D.E.; Morrow, C.A.; Byerlee, J.D.

    1982-01-01

    The injection of swelling-clay slurries into joints or faults at a deep-burial nuclear waste disposal site may result in signficant permeability reductions for the effective containment of radioactive wastes. In an experiment conducted to illustrate the permeability change accompanying clay swelling, a coarse stone with interconnected pore spaces was injected with a clay-electrolyte slurry, modelling the pressure-grouting of a fractured repository rock. Subsequently, solutions with lower electroylte concentrations were driven through the clay-filled stone, corresponding to migration of lower salinity ground-waters through the clay-grouted fracture. The initial injection procedure reduced the permeability of the stone from 1--10 darcies to 700 nanodarcies; the changes in solution composition decreased permeability by more than 2 additional orders of magnitude to 3 nanodarcies. For application at a nuclear waste repository, the electrolyte concentration of the injected clay slurry should be made higher than that of the ground-water in the host rock. Subesquent interaction of the ground-water with the clays would initiate swelling and create the additional, post-injection permeability reductions that may be important in preventing the escape of buried radioactive wastes. The measured permeability of the clay filling is considerably lower than that of cement tested for borehole plugging. Clays also have the advantage over cement and chemical grouts in that they are geologically stable at relatively low temperatures and have a high capacity for radionuclide adsorption

  7. Comprehensive review of geosynthetic clay liner and compacted clay liner

    Shankar, M. Uma; Muthukumar, M.

    2017-11-01

    Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

  8. Wave liquefaction in soils with clay content

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

  9. What makes a natural clay antibacterial?

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

  10. CATSIUS CLAY PROJECT: Calculation and testing of behaviour of unsaturated clay as barrier in radioactive waste repositories: stage 3: validation exercises at a large in situ scale

    Alonso, E E; Alcoverro, J

    1999-07-01

    Stage 3 of CATSIUS CLAY Project: Validation Exercises at a Large in situ Scale includes two Benchmarks: Benchmark 3.1: In situ Hydration of Boom Clay Pellets (BACCHUS 2) and Benchmark 3.2: FEBEX Mock-up Test. The BACCHUS 2 in situ test was performed in the HADES underground laboratory (Mol, Belgium) to demonstrate and optimize an installation procedure for a clay based material and to study its hydration process. After drilling a vertical shaft (540 mm in diameter, 3.0 m in length) in the host Boom clay, a central filter (90 mm in diameter) was placed, the remaining space was filled with a mixture of clay pellets and clay powder and the assembly was sealed at the upper end by a resin plug (0.20 m in thickness) over which concrete was poured. The test was instrumented so that it could be used as a validation experiment. Total stress, pore water pressure and water content measurements were performed both in the backfill material and in the surrounding clay massif. Once the installation was complete, the natural hydration of the backfill material began (day 0). To accelerate the hydration process, on day 516 water was injected through the central filter. On day 624, after the saturation of the backfill was reached, the hydraulic circuit was closed and the undrained response of the system backfill-host clay was monitored until an overall steady state was reached. Partners were asked to provide predictions for the evolution of the pore water pressure and total pressure of various points where appropriate sensors are installed. This benchmark addresses the Hydro-Mechanical response of an unsaturated low density clay barrier under natural and artificial hydration. (Author)

  11. CATSIUS CLAY PROJECT: Calculation and testing of behaviour of unsaturated clay as barrier in radioactive waste repositories: stage 3: validation exercises at a large in situ scale

    Alonso, E. E.; Alcoverro, J.

    1999-01-01

    Stage 3 of CATSIUS CLAY Project: Validation Exercises at a Large in situ Scale includes two Benchmarks: Benchmark 3.1: In situ Hydration of Boom Clay Pellets (BACCHUS 2) and Benchmark 3.2: FEBEX Mock-up Test. The BACCHUS 2 in situ test was performed in the HADES underground laboratory (Mol, Belgium) to demonstrate and optimize an installation procedure for a clay based material and to study its hydration process. After drilling a vertical shaft (540 mm in diameter, 3.0 m in length) in the host Boom clay, a central filter (90 mm in diameter) was placed, the remaining space was filled with a mixture of clay pellets and clay powder and the assembly was sealed at the upper end by a resin plug (0.20 m in thickness) over which concrete was poured. The test was instrumented so that it could be used as a validation experiment. Total stress, pore water pressure and water content measurements were performed both in the backfill material and in the surrounding clay massif. Once the installation was complete, the natural hydration of the backfill material began (day 0). To accelerate the hydration process, on day 516 water was injected through the central filter. On day 624, after the saturation of the backfill was reached, the hydraulic circuit was closed and the undrained response of the system backfill-host clay was monitored until an overall steady state was reached. Partners were asked to provide predictions for the evolution of the pore water pressure and total pressure of various points where appropriate sensors are installed. This benchmark addresses the Hydro-Mechanical response of an unsaturated low density clay barrier under natural and artificial hydration. (Author)

  12. Predictive modelling of an excavation test in indurated clay

    Garitte, B.; Vaunat, J.; Gens, A.; Vietor, T.

    2010-01-01

    Document available in extended abstract form only. This Abstract presents the predictive hydro-mechanical (HM) modelling of an excavation performed in Opalinus clay in the Mont Terri underground laboratory. Niche 2 was excavated in the shaly facies of Opalinus clay from gallery 08. The area surrounding the gallery was intensively instrumented. The geology of Mont Terri is described in Thury and Bosssart (1999) and the parameters used in the analysis were taken from Bock (2009). The stress state is derived from Martin and Lanyion (2003). Gallery 08 is horseshoe shaped and has a mean radius of 2.25 m. It was excavated with a road header at a mean velocity of 1 m/day starting on January 30, 2008 (Gallery chainage 43.8) and ending on June 30, 2008 (Gallery chainage 123.8) with a stop from March 18, to April 24, to instrument the area of niche 2. Niche 2 was excavated by successive blastings 1.3 m deep until reaching a distance of 24 m from the gallery 08 wall. Advance was continuous from October 13, to November 7 with the exception of three stops of 3, 5 and 4 days. The niche has an average diameter of 4.5 m and has a slight upward slope of 0.98%. The excavation of gallery 08 from chainage 43.8 to chainage 123.8 and of the niche was simulated by relaxing the normal total stress and water pressure from the value before excavation to 0. The gallery advance rate was simulated in an approximate manner by applying successively the excavation procedure to 9 m long gallery sections. In the case of the niche, the blasting scheme and the application of the shotcrete was closely reproduced. The three dimensional geometry used in the simulation is shown. The coupled hydro-mechanical formulation used for the analysis is based on the simultaneous solution of the balance equation for solid mass, water mass and momentum (equilibrium). In accordance with field observations, it has been assumed that the medium remains saturated throughout. The formulation was completed with a number of

  13. SBR Brazilian organophilic/clay nanocomposites

    Guimaraes, Thiago R.; Valenzuela-Diaz, Francisco R.; Morales, Ana Rita; Paiva, Lucilene B.

    2009-01-01

    The aim of this work is the obtaining of SBR composites using a Brazilian raw bentonite and the same bentonite treated with an organic salt. The clays were characterized by XRD. The clay addition in the composites was 10 pcr. The composites were characterized by XRD and had measured theirs tension strength (TS). The composite with Brazilian treated clay showed TS 233% higher than a composite with no clay, 133% higher than a composite with Cloisite 30B organophilic clay and 17% lower than a composite with Cloisite 20 A organophilic clay. XRD and TS data evidence that the composite with Brazilian treated clay is an intercalated nanocomposite. (author)

  14. Thermal Behaviour of clay formations

    Tassoni, E.

    1985-01-01

    The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm -1 . 0 C -1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

  15. Investigations on self-sealing of indurated clay - Part of the NF-PRO project. Final report

    Zhang, Chun-Liang; Rothfuchs, T.; Dittrich, J.; Mueller, J.

    2008-03-01

    The self-sealing potential of the Callovo-Oxfordian argillite and the Opalinus clay was investigated on strongly damaged samples. Gas permeability as a function of the confining stress before and after water resaturation was measured. Not only normally-sized but also large-scale and cylindrical ring-shaped samples were tested. Each test lasted over a time period of 5 to 16 months. The experimental findings are: 1. The permeability of the pre-damaged samples decreased significantly with a concurrent increase of the confining stress due to fracture closure. The permeability measured in radial direction on a hollow sample decreased from 10 -15 m 2 at a low confining stress of 1 MPa to 10 -21 m 2 at 28 MPa. The compression of the sample led to plastic closure of pre-existing fractures, leading to a significantly lower permeability after unloading. A similar permeability reduction with increasing confining stress was also observed in axial direction, parallel to the bedding plane. But, at low confining stresses below 10 MPa, the axial permeability parallel to the bedding was about one to two orders of magnitude higher than the radial one perpendicular to the bedding. The hydraulic anisotropy vanishes off with increasing the confining stress. 2. The permeability of fractured clay rocks was dominated by the confining stress normal to the fracture plane. This was validated by gas permeability measurements on a large sample (D=260 mm/L=616 mm) with fractures oriented parallel to the sample axis. The increase of the lateral stress from 3 to 18 MPa at 19 MPa axial stress led to a decrease of axial permeability from 10 -13 to 10 -19 m 2 . 3. The permeability od damaged clay rocks decreased also with time due to the time-dependent compaction of pores and fractures. On the pre-damaged samples, a permeability reduction by a factor of 4 to 8 was observed over two months at a low confining stress of 1.5 MPa. 4. The high swelling potential of the studied clay rocks led to the

  16. Effect of carbonate content on the mechanical behaviour of clay fault-gouges

    Bakker, Elisenda; Niemeijer, André; Hangx, Suzanne; Spiers, Chris

    2015-04-01

    -rich caprock material we used Opalinus Claystone (Mont Terri, Switserland), which is considered to be an analogue for many shaly caprocks in Europe. We performed rotary shear experiments at in-situ reservoir conditions (T = 20-150˚C, σneff = 50 MPa, Pp = 25 MPa) at shear velocities of 0.22 -100 μm/s. Preliminary results show that the frictional strength of the carbonate-free, natural clay-rich caprock samples is 40-50% lower than for the pure calcite samples. Typical steady-state friction coefficient values obtained for the carbonate-free clay samples are ~0.3-0.4. These values are significantly smaller than the values of ~0.6-0.7 obtained for pure calcite. The friction coefficient values obtained for the mixture plot between the carbonate-free and pure calcite values. The samples show predominantly velocity-strengthening behaviour. However, the 90% pure calcite (and 10% clay-rich caprock) and 100% pure calcite samples show velocity-weakening behaviour at 100-150°C. This suggests that large amounts of carbonates, and thus significant carbonate precipitation as a result of CO2-exposure, are required to cause a transition from aseismic to seismic behaviour, at least under the experimental conditions investigated here.

  17. Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

    Schjønning, P.; de Jonge, L.W.; Munkholm, L.J.; Moldrup, P.; Christensen, B.T.; Olesen, J.E.

    2011-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

  18. Disposal of radioactive waste into clay layers the most natural option

    Baetsle, L.H.; Bonne, A.

    1990-01-01

    Among the geological formations suitable for the disposal of radioactive waste, the clay formations provide outstanding opportunities : impermeable for water, self-healing, strongly absorbing for ions, widespread in nature. The self-healing properties of large clay deposits have been demonstrated by their auto-sealing and plastic response to tectonic stress and magmatic intrusion. The discovery of fossil trees preserved after geologic periods of burial in clay is one of the most dramatic illustrations of their entombment ability. The physicochemical and hydrologic characteristics of the Boom clay are very favorable for the confinement of migrating radionuclides within the layer. Except for the extremely long half-lives ( 237 Np, 129 I,...) no radionuclide can escape from the clay body. The effects of heat, metal corrosion, material interaction and biochemical degradation on the natural properties of the clay layer are discussed in some detail and related to the natural properties of the clay formation which have to stay unaltered for geologic periods. The first Safety Assessment Report, established by NIRAS-ONDRAF in close collaboration with SCK-CEN, has been submitted to a multi-disciplinary task force which is to advise the Belgian Government on the suitability of the Boom clay layer below the Nuclear Research site of Mol as a potential host formation for nuclear waste coming from the electronuclear program. 13 refs., 2 figs., 1 tab

  19. Fluoride retention by kaolin clay

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...... capacity was found to be 18.3 meq/100 g at pH 6 and 8.6 meq/100 g at pH 7. A competitive Langmuir sorption isotherm where sorption is dependant on both pH and fluoride concentration is employed to characterise the experimental sorption and desorption data. The sorption and desorption isotherms revealed...

  20. Boron enrichment in martian clay.

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  1. In situ geochemical properties of clays subject to thermal loading

    Chapman, N.A.

    1980-01-01

    Compositional variation and geochemical environment in an argillaceous unit are a function of age, depth of burial and mode of origin. This paper considers the variation limits likely to be encountered in potential repository host rocks and examines the significance of factors such as porosity, pore-fluid pressure, total fluid content, and major and accessory mineral component behaviors in controlling the geochemical environment in the neighbourhood of a thermally active waste canister. Particular attention is paid to the use of Eh-pH diagrams in assessing corrosion environments and nuclide speciation. The paper outlines the variables which must be considered when endeavouring to interpret such plots (e.g. temperature, concentration, concurrent reactions and probabilities) and uses the behavior of various iron minerals found in clay deposits under specific conditions to illustrate the complexities. The overall thermal stability of various clay and accessory minerals is discussed and extended to attempt to predict behavior under deep repository conditions, using available data on the diagenetic characteristics of clay-rich sediments. The physical behavior of fluids in plastic clays is considered and methods evaluated for deriving induced geochemical conditions in a thermally active repository. The latter section is particularly related to canister corrosion studies, in situ experiments, and waste dissolution parameters

  2. Hydro-mechanical properties of the red salt clay (T4) - Natural analogue of a clay barrier

    Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Boettge, V.

    2010-01-01

    Document available in extended abstract form only. Long-term storage of high-level radioactive waste in deep geologic formations is worldwide the only accepted solution to warranty long term safety. Besides clay and crystalline rocks, salt is one of the potential host-rock candidates, mainly favored in Germany. As salts rocks are highly soluble their barrier integrity against water inflow from the cap rock is questionable. Argillaceous cap rocks or intercalated clay layers may act as protective shield in the hanging wall above a repository, thus providing a multi-barrier system. The aims of our study are twofold: 1) to characterize the mineralogical, hydraulic and rock-mechanical properties of the so-called Red Salt Clay (T4) as natural analogue of a clay barriers represented by different states of induration corresponding to various depth of burial diagenesis; 2) to demonstrate the favoured barrier properties of an argillaceous layer in the top of a salt formation undergoing dynamic processes such as rock bursts. The so-called Red Salt Clay (T4) is deposited as clay rich clastic sediment at the base of the Aller-series forming a persistent lateral layer above the lower Zechstein-series. The thickness of the clay-formation becomes smaller with decreasing distance from the border of the basin, i.e. from ∼15 m at Rossleben, over 7 m at Bernburg to 3.5 m at Zielitz, all in Saxony-Anhalt, D). The mineralogical composition of the Red Salt Clay varies, e.g. average composition for the Teutschenthal area: clay minerals 54% (Chlorite: 8%; Illite/Muscovite: 46%); quartz: 22%; anhydrite: 15%; accessory gypsum; Halite: 6%, Hematite: ∼ 2%). The geochemical and mineralogical composition of the Red Salt Clay represents a final state of natural salt-clay-systems, thus standing as a natural analogue for bentonite-based sealing systems in contact with high-saline solutions (e.g. saturated NaCl-solution, solutions with various Mg 2+ -, K + -, SO 4 2- - concentrations). The

  3. Stools - pale or clay-colored

    ... gov/ency/article/003129.htm Stools - pale or clay-colored To use the sharing features on this page, please enable JavaScript. Stools that are pale, clay, or putty-colored may be due to problems ...

  4. Phosphonium modified clay/polyimide nanocomposites

    Ceylan, Hatice; Çakmakçi, Emrah; Beyler-Çiǧil, Asli; Kahraman, Memet Vezir

    2014-01-01

    In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA)

  5. Geotechnical properties of Karwar marine clay

    Bhat, S.T.; Nayak, B.U.; Naik, R.L.

    Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

  6. Additive to clay drilling muds

    Voytenko, V.S.; Nekrasova, V.B.; Nikitinskiy, E.L.; Ponomarev, V.N.

    1984-01-01

    The purpose of the invention is to improve the lubricating and strengthening properties of clay drilling muds. This goal is achieved because the lubricating and strengthening additive used is waste from the pulp and paper industry at the stage of reprocessing crude sulfate soap into phytosterol.

  7. Picasso Masks: Cubism in Clay

    Daddino, Michelle

    2010-01-01

    This article describes an art project developed by the author which provides a way to further the children's understanding of Picasso's Cubism style in 3-D. Through this project, upper-elementary students learn a bit about the life and art of Picasso as they gain a firm understanding of the style of art known as Cubism, and apply clay techniques…

  8. ADSORPTION OF SURFACTANT ON CLAYS

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  9. Organic Synthesis using Clay Catalysts

    cept, though not new, has received enormous attention in recent times. The desire to make ... which they are divided into four main groups such as, illite, smectite .... acid or driving out NH3 by heating the NH4 + ion treated clay. It is clear from ...

  10. 21 CFR 186.1256 - Clay (kaolin).

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain...

  11. generalized constitutive model for stabilized quick clay

    QUICK CLAY. PANCRAS MUGISHAGWE BUJULU AND GUSTAV GRIMSTAD. ABSTRACT. An experimentally-based two yield surface constitutive model for cemented quick clay has been ... Clay Model, the Koiter Rule and two Mapping Rules. .... models, where a mobilization formulation is used, this is independent of q.

  12. Clay Cuffman: A Cool, Calm, Relaxed Guy

    Booth, Gina

    2010-01-01

    This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

  13. The systems containing clays and clay minerals from modified drug release: a review.

    Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

    2013-03-01

    Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. The effect of clay on the dissolution of nuclear waste glass

    Lemmens, K.

    2001-09-01

    In a nuclear waste repository, the waste glass can interact with metals, backfill materials (if present) and natural host rock. Of the various host rocks considered, clays are often reported to delay the onset of the apparent glass saturation, where the glass dissolution rate becomes very small. This effect is ascribed to the sorption of silica or other glass components on the clay. This can have two consequences: (1) the decrease of the silica concentration in solution increases the driving force for further dissolution of glass silica, and (2) the transfer of relatively insoluble glass components (mainly silica) from the glass surface to the clay makes the alteration layer less protective. In recent literature, the latter explanation has gained credibility. The impact of the environmental materials on the glass surface layers is however not well understood. Although the glass dissolution can initially be enhanced by clay, there are arguments to assume that it will decrease to very low values after a long time. Whether this will indeed be the case, depends on the fate of the released glass components in the clay. If they are sorbed on specific sites, it is likely that saturation of the clay will occur. If however the released glass components are removed by precipitation (growth of pre-existing or new secondary phases), saturation of the clay is less likely, and the process can continue until exhaustion of one of the system components. There are indications that the latter mechanism can occur for varying glass compositions in Boom Clay and FoCa clay. If sorption or precipitation prevents the formation of protective surface layers, the glass dissolution can in principle proceed at a high rate. High silica concentrations are assumed to decrease the dissolution rate (by a solution saturation effect or by the impact on the properties of the glass alteration layer). In glass corrosion tests at high clay concentrations, silica concentrations are, however, often higher

  15. The effect of clay on the dissolution of nuclear waste glass

    Lemmens, K.

    2001-01-01

    In a nuclear waste repository, the waste glass can interact with metals, backfill materials (if present) and natural host rock. Of the various host rocks considered, clays are often reported to delay the onset of the apparent glass saturation, where the glass dissolution rate becomes very small. This effect is ascribed to the sorption of silica or other glass components on the clay. This can have two consequences: (1) the decrease of the silica concentration in solution increases the driving force for further dissolution of glass silica, and (2) the transfer of relatively insoluble glass components (mainly silica) from the glass surface to the clay makes the alteration layer less protective. In recent literature, the latter explanation has gained credibility. The impact of the environmental materials on the glass surface layers is however not well understood. Although the glass dissolution can initially be enhanced by clay, there are arguments to assume that it will decrease to very low values after a long time. Whether this will indeed be the case, depends on the fate of the released glass components in the clay. If they are sorbed on specific sites, it is likely that saturation of the clay will occur. If however the released glass components are removed by precipitation (growth of pre-existing or new secondary phases), saturation of the clay is less likely, and the process can continue until exhaustion of one of the system components. There are indications that the latter mechanism can occur for varying glass compositions in Boom Clay and FoCa clay. If sorption or precipitation prevents the formation of protective surface layers, the glass dissolution can in principle proceed at a high rate. High silica concentrations are assumed to decrease the dissolution rate (by a solution saturation effect or by the impact on the properties of the glass alteration layer). In glass corrosion tests at high clay concentrations, silica concentrations are, however, often higher

  16. Mineral acquisition from clay by budongo forest chimpanzees

    Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay

  17. Preparation and characterization of bentonite organo clay

    Bertagnolli, C.; Almeida Neto, A.F.; Silva, M.G.C.

    2009-01-01

    Bentonite clays organically modified have great potential use for environmental remediation, especially in the separation of organic compounds from the water. The aim of this work was the preparation of organophilic clays from 'Verde-Lodo' bentonite clay with the quaternary ammonium salts cetyl-pyridinium chloride and benzalkonium chloride. The materials obtained were characterized by XRD, thermogravimetric analyses, Helium picnometry, SEM and energy dispersive X-ray techniques. The results show consistently successful synthesis of the organoclay through the increase in the basal spacing, as well as salt elimination picks and presence of carbon and chlorine in the modified clays; they are inexistent elements in the natural clay. (author)

  18. Thermomechanical behaviour of boom clay

    Sultan, N.; Delage, P.; Cui, Y.J.

    2000-01-01

    Special attention has been recently paid on temperature effects on the behaviour of deep saturated clays, in relation with nuclear deep waste storage. However, few experimental data are presently available, and existing constitutive models need to be completed. This note is aimed at completing, both experimentally and theoretically, the understanding of the effects of the over-consolidation ration on the thermal volume changes of Boom clay (Belgium). The experimental data obtained here are in a good agreement with existing data. As a complement to existing data, they are used to develop a new elastoplastic model. The adoption of a second coupled plastic mechanism provides good simulations on a complex thermo-mechanical path. (authors)

  19. Hyperspectral analysis of clay minerals

    Janaki Rama Suresh, G.; Sreenivas, K.; Sivasamy, R.

    2014-11-01

    A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 μm spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

  20. Processes of cation migration in clay-rocks: Final Scientific Report of the CatClay European Project

    Altmann, S.; Aertsens, M.; Appelo, T.; Bruggeman, C.; Gaboreau, S.; Glaus, M.; Jacquier, P.; Kupcik, T.; Maes, N.; Montoya, V.; Rabung, T.; Robinet, J.-C.; Savoye, S.; Schaefer, T.; Tournassat, C.; Van Laer, L.; Van Loon, L.

    2015-07-01

    In the framework of the feasibility studies on the radioactive waste disposal in deep argillaceous formations, it is now well established that the transport properties of solutes in clay rocks, i.e. parameter values for Fick's law, are mainly governed by the negatively charged clay mineral surface. While a good understanding of the diffusive behaviour of non-reactive anionic and neutral species is now achieved, much effort has to be placed on improving understanding of coupled sorption/diffusion phenomena for sorbing cations. Indeed, several cations known to form highly stable surface complexes with sites on mineral surfaces migrate more deeply into clay rock than expected. Therefore, the overall objective of the EC CatClay project is to address this issue, using a 'bottom-up' approach, in which simpler, analogous systems (here a compacted clay, 'pure' illite) are experimentally studied and modelled, and then the transferability of these results to more complex materials, i.e. the clay rocks under consideration in France, Switzerland and Belgium for hosting radioactive waste disposal facilities, is verified. The cations of interest were chosen for covering a representative range of cations families: from a moderately sorbing cation, the strontium, to three strongly sorbing cations, Co(II), Zn(II) and Eu(III). For the 4 years of this project, much effort was devoted to developing and applying specific experimental methods needed for acquiring the high precision, reliable data needed to test the alternative hypotheses represented by different conceptual-numerical models. The enhanced diffusion of the sorbing cations of interest was confirmed both in the simpler analogous illite system for Sr 2+ , Co(II) and Zn(II), but also in the natural clay rocks, except for Eu(III). First modelling approach including diffusion in the diffuse double layer (DDL) promisingly succeeded in reproducing the experimental data under the various conditions both in

  1. Clays in natural and engineered barriers for radioactive waste confinement - 4. International meeting. Book of abstracts

    2010-01-01

    The 4. edition of the International Meeting 'Clays in Natural and Engineered Barriers for Radioactive Waste Confinement' took place at the 'Cite Internationale des Congres' of Nantes (France). Approximately 500 participants (from about 20 different countries) attended the meeting. All the abstracts (oral and poster sessions) are included in these proceedings. The purpose of this 4. international conference is to gather specialists in the different disciplines related to clays and clay minerals, with scientists from organisations engaged in radioactive waste disposal, in order to evaluate the progress of the research conducted in that field. Multidisciplinary approaches including geology, mineralogy, geochemistry, rheology, geomechanics of clays are required in order to provide a detailed characterisation of the geological host formations considered for the disposal of radioactive waste and to assess the behaviour of engineered and natural barriers when submitted to various types of perturbations induced by disposal facilities. The major objectives for the experimental programs are constituted by the performance evaluation for the natural barrier as well as the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations. This is being or will be conducted in underground research laboratories, for interpreting the subsequent scientific results, for modelling the long-term behaviour of radioactive waste repositories and for carrying out safety assessment exercises. This conference covers all the aspects of clay characterisation and behaviour relevant to the confinement of radionuclides in clay, considered at various time scales and locations, from the descriptions of basic phenomenological processes to the global understanding of the performance and safety at repository and geological scales. Most of the topics covered by the programme of the conference are in line with the general objectives

  2. Titanium alloys as alternative material for the supercontainer shell in the KBS-3H concept. A preliminary Ti-clay interaction study

    Wersin, Paul [Gruner Ltd (Switzerland); Grolimund, Daniel [Paul Scherrer Institute (Switzerland); Kumpulainen, Sirpa; Kiviranta, Leena [BandTech Oy (Finland); Brendle, Jocelyne [University of Mulhouse (France); Snellman, Margit [Saanio and Riekkola Oy (Finland)

    2010-12-15

    more light on Ti-clay interaction processes and on the Ti species resulting from these interactions. Purified MX-80 bentonite was mixed with metallic Ti nano powder and foil at different pH and temperature conditions. After several months, solid and solute samples from the first set of tests were analyzed by wet chemistry and quantitative X-ray fluorescence analysis. The chemical speciation of Ti was analyzed with XAS. In addition to reacted samples, a number of reference and starting materials (e.g. MX-80, Rokle bentonite, Opalinus Clay, Illite du Puy) were characterized by XRF and XAS. Preliminary results can be summarized as: - Natural clay materials contain significant but variable amounts of Ti. The standard purification procedure for bentonites to remove accessories does not or only barely remove Ti. - The Ti in the natural clay materials Rokle bentonite, Opalinus Clay and Illite du Puy occurs as microcrystalline TiO{sub 2} (presumably as anatase). On the other hand, the Ti spectra in MX-80 suggest the presence of structural Ti in the smectite, but the evidence is not conclusive so far. - The exposure of purified MX-80 to titanium powder at room temperature within a period of five months did not lead to measurable additional Ti in the clay. A second series of experiments with synthetic 'Ti-free' montmorillonite at higher temperatures (80 deg C) was conducted for a period of 4.5 months in order to increase Ti transfer rates from the metal surfaces to the clay. As revealed from spectroscopic analysis (micro-XRF and XANES) on the reacted materials, the use of synthetic montmorillonite combined with the increase of temperature allowed to partly overcome the experimental problems noted in the first series. Thus, Ti background concentrations were effectively very low and Ti transfer to the clay could be identified with spectroscopic analysis. On the other hand, the spectroscopic data highlighted further weaknesses in the setup. Thus the use of Ti nano powder is not

  3. Titanium alloys as alternative material for the supercontainer shell in the KBS-3H concept. A preliminary Ti-clay interaction study

    Wersin, Paul (Gruner Ltd (Switzerland)); Grolimund, Daniel (Paul Scherrer Institute (Switzerland)); Kumpulainen, Sirpa; Kiviranta, Leena (BandTech Oy (Finland)); Brendle, Jocelyne (University of Mulhouse (France)); Snellman, Margit (Saanio and Riekkola Oy (Finland))

    2010-12-15

    to shed more light on Ti-clay interaction processes and on the Ti species resulting from these interactions. Purified MX-80 bentonite was mixed with metallic Ti nano powder and foil at different pH and temperature conditions. After several months, solid and solute samples from the first set of tests were analyzed by wet chemistry and quantitative X-ray fluorescence analysis. The chemical speciation of Ti was analyzed with XAS. In addition to reacted samples, a number of reference and starting materials (e.g. MX-80, Rokle bentonite, Opalinus Clay, Illite du Puy) were characterized by XRF and XAS. Preliminary results can be summarized as: - Natural clay materials contain significant but variable amounts of Ti. The standard purification procedure for bentonites to remove accessories does not or only barely remove Ti. - The Ti in the natural clay materials Rokle bentonite, Opalinus Clay and Illite du Puy occurs as microcrystalline TiO{sub 2} (presumably as anatase). On the other hand, the Ti spectra in MX-80 suggest the presence of structural Ti in the smectite, but the evidence is not conclusive so far. - The exposure of purified MX-80 to titanium powder at room temperature within a period of five months did not lead to measurable additional Ti in the clay. A second series of experiments with synthetic 'Ti-free' montmorillonite at higher temperatures (80 deg C) was conducted for a period of 4.5 months in order to increase Ti transfer rates from the metal surfaces to the clay. As revealed from spectroscopic analysis (micro-XRF and XANES) on the reacted materials, the use of synthetic montmorillonite combined with the increase of temperature allowed to partly overcome the experimental problems noted in the first series. Thus, Ti background concentrations were effectively very low and Ti transfer to the clay could be identified with spectroscopic analysis. On the other hand, the spectroscopic data highlighted further weaknesses in the setup. Thus the use of Ti

  4. Geological evolution of clay sediments: the petroleum exploration vision

    Schneider, F.

    2004-01-01

    The radioactive waste isolation capacity assessment for a clay sediment host rock is link: (1) to the understanding of their present state properties and 3-D repartition (from basin evolution, including sedimentary and diagenetic process); and (2) to the prediction of their future evolution during the next million years. For petroleum exploration, basin modelling aims at reconstructing the accumulation of hydrocarbons at basin scale, and at geological timescale, taking into account the effects of kinematics displacements, sedimentation, erosion, compaction, temperatures history, overpressures and fluids flows (water and hydrocarbons). Furthermore, explorationists wish to address overpressure reconstruction in order to estimate the risks of drilling. Clay sediments are of interest for petroleum exploration because source rocks and seal are generally composed of them. Nevertheless, in spite of their occurrence in nature their evolution at geological timescale is not well understood. And, most of the knowledge has been achieved by those working in the realms of soils mechanics and civil engineering until the present geological investigations for long term radioactive waste repositories. Application of this knowledge to clay sediment is considered to be valid within the first hundreds of meters at the top of the sedimentary pile, according to a repository depth. This paper is dedicated to the sedimentary rocks behaviour at geological timescale. This behaviour is characterised by: (1) the deposition of the sediment; (2) the loading path at geological timescale; (3) the constitutive law which includes the consolidation process and the rupture criteria; and (4) the parameters evolution related to consolidation. (author)

  5. Safety-relevant hydrogeological properties of the claystone barrier of a Swiss radioactive waste repository: An evaluation using multiple lines of evidence

    Gautschi, Andreas

    2017-09-01

    In Switzerland, the Opalinus Clay - a Jurassic (Aalenian) claystone formation - has been proposed as the first-priority host rock for a deep geological repository for both low- and intermediate-level and high-level radioactive wastes. An extensive site and host rock investigation programme has been carried out during the past 30 years in Northern Switzerland, comprising extensive 2D and 3D seismic surveys, a series of deep boreholes within and around potential geological siting regions, experiments in the international Mont Terri Rock Laboratory, compilations of data from Opalinus Clay in railway and motorway tunnels and comparisons with similar rocks. The hydrogeological properties of the Opalinus Clay that are relevant from the viewpoint of long-term safety are described and illustrated. The main conclusions are supported by multiple lines of evidence, demonstrating consistency of conclusions based on hydraulic properties, porewater chemistry, distribution of natural tracers across the Opalinus Clay as well as small- and large-scale diffusion models and the derived conceptual understanding of solute transport.

  6. Speciation of neptunium during migration in clay rock; Speziation von Neptunium bei der Migration in Tongestein

    Froehlich, Daniel

    2011-12-15

    The present work was performed within a fellowship of the interdisciplinary research training group 826 ''trace analysis of elemental species: method development and application'' funded by the German Research Foundation (DFG) and the federal state Rheinland-Pfalz. Aim of this work was to gain new knowledge of the interaction between neptunium and natural clay rock with respect to the disposal of high-level nuclear waste in deep geological formations. The isotope {sup 237}Np with its long half-life of more than two million years will be one of main contributors to the radiotoxicity of the radioactive waste material after storage times of more than 1000 years. In aqueous solution under environmental relevant conditions Np can exist in the oxidation states +IV and +V. Due to its high solubility and higher mobility Np(V) is the much more hazardous species compared to Np(IV). Opalinus Clay (OPA) from Mont Terri, Switzerland, was used as a natural reference material in the migration studies. The focus of this work was on speciation of Np on the mineral surface by synchrotron based X-ray absorption spectroscopy (EXAFS/XANES). The interaction between Np(V) and OPA was studied in batch sorption and diffusion experiments in dependence of various experimental parameters (e.g. pH, temperature, background electrolyte, effect of humic acid, concurrence with U(VI), aerobic/anaerobic conditions). The investigation of Np speciation was performed on two types of samples. Powder samples from batch experiments were prepared under aerobic and anaerobic conditions and measured by EXAFS spectroscopy. Diffusion samples and OPA thin sections contacted with Np(V) were analyzed by locally resolved μ-XANES measurements on enrichments of Np. A combination with μ-XRF (X-ray fluorescence) mapping and μ-XRD (X-ray diffraction) measurements provided further information about the spatial distribution of Np and other elements contained in OPA as well as crystalline mineral

  7. Titanium alloys as alternative material for the supercontainer shell in the KBS-3H concept: A preliminary Ti-clay interaction study

    Wersin, P. [Gruner Ltd, Basel (Switzerland); Grolimund, D. [Paul Scherrer Inst., Villigen (Switzerland); Kumpulainen, S.; Kiviranta, L. [B and Tech Oy, Helsinki (Finland); Brendle, J. [Mulhouse Univ. (France); Snellman, M. [Saanio and Riekkola Oy, Helsinki (Finland)

    2011-12-15

    to shed more light on Ticlay interaction processes and on the Ti species resulting from these interactions. Purified MX-80 bentonite was mixed with metallic Ti nanopowder and foil at different pH and temperature conditions. After several months, solid and solute samples from the first set of tests were analyzed by wet chemistry and quantitative X-ray fluorescence analysis. The chemical speciation of Ti was analyzed with XAS. In addition to reacted samples, a number of reference and starting materials (e.g. MX-80, Rokle bentonite, Opalinus Clay, Illite du Puy) were characterized by XRF and XAS. Preliminary results can be summarized as: Natural clay materials contain significant but variable amounts of Ti. The standard purification procedure for bentonites to remove accessories does not or only barely remove Ti. The Ti in the natural clay materials Rokle bentonite, Opalinus Clay and Illite du Puy occurs as microcrystalline TiO{sub 2} (presumably as anatase). On the other hand, the Ti spectra in MX-80 suggest the presence of structural Ti in the smectite, but the evidence is not conclusive so far. The exposure of purified MX-80 to titanium powder at room temperature within a period of five months did not lead to measurable additional Ti in the clay. A second series of experiments with synthetic 'Ti-free' montmorillonite at higher temperatures (80 deg C) was conducted for a period of 4.5 months in order to increase Ti transfer rates from the metal surfaces to the clay. As revealed from spectroscopic analysis (micro-XRF and XANES) on the reacted materials, the use of synthetic montmorillonite combined with the increase of temperature allowed to partly overcome the experimental problems noted in the first series. Thus, Ti background concentrations were effectively very low and Ti transfer to the clay could be identified with spectroscopic analysis. On the other hand, the spectroscopic data highlighted further weaknesses in the setup. Thus the use of Ti nanopowder

  8. Organophilization and characterization of commercial bentonite clays

    Cunha, B.B. da; Lima, J.C.C.; Alves, A.M.; Araujo, E.M.; Melo, T.J.A. de

    2012-01-01

    Bentonite clay is a plastic changes resulting from volcanic ash, consisting mostly of montmorillonite. The state of Paraiba is a major source of bentonite clay from Brazil, where the main oil fields are located in Boa Vista and represents the largest national production of raw and beneficiated bentonite. Aimed at the commercial value of this type of clay and its high applicability in the polls, this article aims to make a comparison between two kinds of clay, a national (Brasgel) and other imported (Cloisite) from organophilization of two commercial bentonite, ionic surfactant with Praepagem WB, and characterize them by XRD, FTIR and TG / DTG. We observe that despite getting inferior properties, the clay presents national values very similar to those presented by imported clay. (author)

  9. Geomechanical behaviour of boom clay under ambient and elevated temperature conditions

    Neerdael, B.; Beaufays, R.; Buyens, M.; Bruyn, D. de; Voet, M.

    1992-01-01

    This research is focused upon in-situ investigations related to the (thermo-) mechanical behaviour of clay. Three main items are covered in this research area: Stress measurements around the underground research facility for radioactive waste disposal using hydraulical stress monitoring stations; detection of micro-fractures in the clay host, mainly using geophysical seismic techniques; long term mechanical behaviour of clay (this last item, studied by ANDRA at Mol, is not described in this paper). The stress monitoring stations appear to be more reliable in getting relative pressure variations with time rather than absolute values of stress, even after studying and improving the characteristics of the surrounding grout. The seismic techniques used to appear to be sensitive and accurate enough for detecting induced fracturation in the clay host, even for the low temperature. This is also in agreement with bench-scale experiments on clay samples intended to quantify the influence of both temperature and consolidation on the velocity. 10 refs., 80 figs., 3 tabs

  10. Mars, clays and the origins of life

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  11. Fracture behavior of polypropylene/clay nanocomposites.

    Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

    2006-12-01

    Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

  12. Multifaceted role of clay minerals in pharmaceuticals

    Khurana, Inderpreet Singh; Kaur, Satvinder; Kaur, Harpreet; Khurana, Rajneet Kaur

    2015-01-01

    The desirable physical and physiochemical properties of clay minerals have led them to play a substantial role in pharmaceutical formulations. Clay minerals like kaolin, smectite and palygorskite-sepiolite are among the world's most valuable industrial minerals and of considerable importance. The elemental features of clay minerals which caused them to be used in pharmaceutical formulations are high specific area, sorption capacity, favorable rheological properties, chemical inertness, swelli...

  13. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  14. Iodide uptake by negatively charged clay interlayers?

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Organic waste treatment with organically modified clays

    Evans, J.C.; Pancoski, S.E.; Alther, G.

    1989-01-01

    The use of organically modified clays in hazardous waste management applications offers a significant new and untapped potential. These clays may be used in the stabilization of organic wastes and organically contaminated soils, for waste water treatment, for oil spill control, for liner systems beneath fuel oil storage tanks, and as a component within liner systems of hazardous waste storage treatment and disposal facilities. Organically modified clays (organophilic clays) may be employed in each of these systems to adsorb organic waste constituents, enhancing the performance of the applications

  16. SPRAYED CLAY TECHNOLOGY FOR THE DEEP REPOSITORY OF HIGH-LEVEL RADIOACTIVE WASTE

    Lucie Hausmannová

    2012-07-01

    Full Text Available The sealing barrier will play very important role in the Czech disposal concept of high level radioactive waste. It follows Swedish SKB3 design where granitic rock environment will host the repository. Swelling clay based materials as the most favorable for sealing purposes were selected. Such clays must fulfill certain requirements (e.g. on swelling properties, hydraulic conductivity or plasticity and must be stable for thousands of years. Better sealing behavior is obtained when the clay is compacted. Technology of the seal construction can vary according to its target dry density. Very high dry density is needed for buffer (sealing around entire canister with radioactive waste. Less strict requirements are on material backfilling the access galleries. It allows compaction to lower dry density than in case of buffer. One of potential technology for backfilling is to compact clay layers in most of the gallery profile by common compaction machines (rollers etc. and to spray clay into the uppermost part afterwards. The paper introduces the research works on sprayed clay technology performed at the Centre of Experimental Geotechnics of the Czech Technical University in Prague. Large scale in situ demonstration of filling of short drift in the Josef Gallery is also mentioned.

  17. Study of the chemo-hydro-mechanical behavior of stiff clays in the context of radioactive waste disposal

    Nguyen, Xuan Phu

    2013-01-01

    The present research aims to understand the chemo-hydro-mechanical behavior of stiff clays through two geological formations, the Boom Clay and the Ypresian clays which are considered as possible host formations for the radioactive wastes disposal in Belgium. The volume change behavior was studied in both intact and reconstituted states, and under different conditions: under K0 and isotropic loading, under loading/unloading loops. The results show that the volume change behavior is governed by the competition between the physico-chemical effect and the mechanical effect, characterized by a threshold stress which corresponds to the swelling stress in terms of structure changes. A constitutive law was developed to capture this aspect. The permeability was determined, compared with the results in literature and correlated with the parameters as void ratio. The permeability variation with depth shows the important role of macro-pores in fluids' transfer. The volume change behavior and permeability of intact Boom Clay and Ypresian clays are also influenced by pore water chemical composition changes which modify the diffuse double layer and give rise to the aggregation of clay particles. The elastic parameters, yield curve and failure envelope of Boom Clay and Ypresian clays were identified. A conceptual elasto-plastic model was developed, accounting for the swelling effects and the competition between the physico-chemical effect and the mechanical effect. (author)

  18. A new and improved methodology for qualitative and quantitative mineralogical analysis of Boom Clay

    Zeelmaekers, E.; Vandenberghe, N.; Honty, M.; De Craen, M.; Derkowski, A.; Van Geet, M.

    2010-01-01

    Document available in extended abstract form only. A good knowledge of the mineralogy of any host formation studied for geological disposal of high-level radioactive waste, is a prerequisite for understanding the geochemical environment which will determine the migration and retention behaviour of radionuclides. In this respect, the Boom Clay mineralogical composition has been extensively studied last decades as reference host formation (e.g. ARCHIMEDEARGILE project, OECD-NEA clay catalogue report) with the aim to provide reliable data for a safety assessment. However, a comparison of the available literature data clearly showed a serious discrepancy among studies, not only in the quantitative, but also in the qualitative mineralogical composition of the Boom Clay (SAFIR II). The reason for such a huge disagreement could be related, among others, to variable grain size distributions of the studied samples (sample heterogeneity) and differences in the methodological approaches. In particular, the unambiguous characterisation of clay minerals and the quantification of mixed-layer phases appeared as an everlasting problem. This study is aimed at achieving a consensus on the qualitative and quantitative mineralogical data of the Boom Clay using the most advanced techniques currently available in the clay science. A new sampling campaign was performed in such a way that samples are (20 in total) more or less regularly distributed over Boom Clay Formation, ensuring that variations in the grain size distributions due to silty clay-clayey silt layers alternations are accounted for. The novel concept based on an analysis at two levels was applied: (1) bulk rock and (2) clay fraction analysis. (1) A bulk rock analysis consists of conventional XRD analysis with the identification of the principal mineral phases. As a next step, the bulk rock was mixed with a ZnO internal standard and experimental diffraction patterns of randomly oriented powders were analyzed using &apos

  19. Long term effects on potential repository sites: the alteration of the Lower Oxford Clay during weathering

    Milowdowski, A.E.; Bloodworth, A.J.; Wilmot, R.D.

    1985-09-01

    The report is one of a short series describing work carried out to investigate the long-term effects of various geological processes on the performance of both shallow and deep repositories for low and intermediate-level radioactive wastes. This paper deals with the alteration as a result of weathering of the Lower Oxford Clay, a potential host rock for shallow disposal of wastes. A description of the Lower Oxford Clay is given, along with the weathering of argillaceous rocks. Investigations of the weathering at the Elstow Storage Depot are described, as well as the implications for radioactive waste disposal. (U.K.)

  20. The geochemical behaviour of selenium in the Boom Clay system - a XANES and EXAFS study

    2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Breynaert, Eric; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Dom, Dirk; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Vancluysen, Jacqueline; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Kirschhock, Christine E.A.; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Maes, Andre; Scheinost, Andreas C.

    2010-01-01

    Document available in extended abstract form only. In Belgium, the Boom Clay formation is studied as a reference host formation for the geological disposal of high-level and long-lived radioactive waste for more than 30 years. This formation mainly consists of mixed clay minerals (illite, inter-stratified illite-smectite), pyrite and immobile and dissolved natural organic matter. Since it provides good sorption capacities, very low permeability, and chemically reducing conditions due to the presence of pyrite (FeS 2 ), the Boom clay formation itself is considered to be the main barrier preventing radionuclide migration from the geological repository. Within this concept for geological storage Se 79 has been identified as one of the critical elements contributing to the final dose to man. Although the sorption and migration behaviour of Se in the Boom Clay system has been thoroughly studied, the speciation of Se in the Boom Clay system has never been identified spectroscopically. In all previous studies, the interpretation of the behaviour of Se in Boom Clay conditions has always been based on circumstantial evidence such as solubility measurements or comparison with the spectroscopically identified speciation of Se in model systems. Based on the XANES analysis, selenite is transformed into Se 0 confirming the previously proposed reduction of selenite in the Boom Clay system. Combination of the mass-balance for Se with the results from linear combination analysis of the XANES spectra provided new evidence for the sorption-reduction mechanism proposed to explain the interaction between Se(IV) and the BC solid phase. In addition, evidence was found that that the fate of Se(IV) in the BC system is completely dominated by its interaction with pyrite present in the Boom Clay. The combined EXAFS analysis of Se in Se 0 reference phases (hexagonal, monoclinic, Se-loaded pyrite) allowed to elucidate further details on the short-range structure of the reaction products formed

  1. Iodide uptake by negatively charged clay interlayers?

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-01-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI (aq) ) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. - Highlights: • Iodide sorption experiments were completed with a diverse array of clay minerals. • Iodide uptake trended with CEC and swamping electrolyte identity and concentration. • Results can be explained by considering the formation of ion pairs in clay interlayers

  2. Sectioning Clay Models Makes Anatomy & Development Tangible

    Howell, Carina Endres; Howell, James Endres

    2010-01-01

    Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

  3. Clay as Thermoluminescence Dosemeter in diagnostic Radiology ...

    This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range, including dose monitoring in abdominal radiography. Clay sourced from Calabar, Nigeria, was tested for thermoluminescence response after irradiation at diagnostic radiology doses, including ...

  4. Climatic control on clay mineral formation

    Many physico-chemical variables like rock-type,climate,topography and exposure age affect weathering environments.In the present study,an attempt is made to understand how the nature of clay minerals formed due to weathering differs in tropical regions receiving high and low rainfall. Clay mineralogy of weathering pro ...

  5. clay nanocomposite by solution intercalation technique

    Polymer–clay nanocomposites of commercial polystyrene (PS) and clay laponite were prepared via solution intercalation technique. Laponite was modified suitably with the well known cationic surfactant cetyltrimethyl ammonium bromide by ion-exchange reaction to render laponite miscible with hydrophobic PS.

  6. The many ways of making anionic clays

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  7. Investigations of salt mortar containing saliferous clay

    Walter, F.

    1992-01-01

    Saliferous clay mortar might be considered for combining individual salt bricks into a dense and tight long-term seal. A specific laboratory program was started to test mortars consisting of halite powder and grey saliferous clay of the Stassfurt from the Bleicherode salt mine. Clay fractions between 0 and 45% were used. The interest focused upon obtaining good workabilities of the mixtures as well as upon the permeability and compression strength of the dried mortar samples. Test results: 1) Without loss of quality the mortar can be mixed using fresh water. Apprx. 18 to 20 weight-% of the solids must be added as mixing water. 2) The porosity and the permeability of the mortar samples increases distinctly when equally coarse-grained salt power is used for mixing. 3) The mean grain size and the grain size distribution of the saliferous clay and the salt powder should be very similar to form a useful mortar. 4) The permeability of the mortar samples decreases with increasing clay fraction from 2 10 -12 m 2 to 2 10 -14 m 2 . The investigated samples, however, were large and dried at 100degC. 5) The uniaxial compressive strength of the clay mortar equals, at an average, only 4 MPa and decreases clearly with increasing clay fraction. Moist mortar samples did not show any measurable compressive strength. 6) Moistened saliferous clay mortar may show little temporary swelling. (orig./HP)

  8. Hygrothermal behavior for a clay brick wall

    Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

    2018-06-01

    In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

  9. Hygrothermal behavior for a clay brick wall

    Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

    2018-01-01

    In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

  10. Geomechanics of clays for radioactive waste disposal

    Come, B.

    1989-01-01

    Clay formations have been studied for many years in the European Community as potential disposal media for radioactive waste. This document brings together results of on-going research about the geomechanical behaviour of natural clay bodies, at normal and elevated temperatures. The work is carried out within the third Community R and D programme on Management and storage of radioactive waste

  11. Quick clay and landslides of clayey soils

    Khaldoun, A.; Moller, P.; Fall, A.; Wegdam, G.; de Leeuw, B.; Méheust, Y.; Fossum, J.O.; Bonn, D.

    2009-01-01

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay

  12. Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications

    Musyoka, Nicholas M

    2014-10-01

    Full Text Available 57 58 59 60 For Peer Review 1 Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications N. M. Musyoka1*, J. Ren1, H. W. Langmi1, D. E. C. Rogers1, B. C. North1, M. Mathe1 and D. Bessarabov2... clear (filtered) extract of cloisite clay, SNC for zeolite from unfiltered cloisite clay extract and SBC for zeolite from unfiltered South African bentonite clay extract. Furfuryl alcohol (Sigma Aldrich, C5H6O2, 98%) and Ethylene gas were used...

  13. 1st International Conference on Calcined Clays for Sustainable Concrete

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  14. Single clay sheets inside electrospun polymer nanofibers

    Sun, Zhaohui

    2005-03-01

    Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

  15. Treatment for cracked and permeable Houston clay

    Vipulanandan, C.; Leung, M.

    1991-01-01

    In this study, the treatability of a field clay (obtained from Houston, Texas) and a clay-sand mixture to reduce their hydraulic conductivity was evaluated. Remolded field clay and clay-sand mixture with and without methanol contamination were treated to reduce their hydraulic conductivity by permeating very dilute grout solutions. The concentration of sodium silicate in the grout solution was 8%, while the solid content in the cement grout was 0.3%. The hydraulic conductivity of permeable Houston clay (hydraulic conductivity >10 -5 cm/sec) could be reduced to less than 10 -7 cm/sec (U.S. EPA limit for soil barriers) by permeating with a selected combination of grout solutions

  16. Some Tests on Heather Field Moraine Clay

    Jørgensen, Mogens B.; Jacobsen, Moust

    This report deals with oedometer tests on three samples of moraine clay from the Heather Field in the English part of the North Sea. The tests have been carried out in the very unelastic apparatus used in Denmark and with special test procedures differing from the ones used elsewhere. In Denmark...... Moraine Clay covers a large part of the surface, and it has therefore been investigated extensively in the field and in the laboratories during the last 25 years. It is to day - from a geotechnical point of view - the best known clay in Denmark. It could therefore be of some interest to compare...... the English North Sea moraine clays with the corresponding Danish Moraine Clays. The Danish test procedures are explained in details and some comments are given in the hope that they may not be banalities all of them....

  17. Active containment systems incorporating modified pillared clays

    Lundie, P.; McLeod, N.

    1997-01-01

    The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation

  18. Clay Dispersibility and Soil Friability-Testing the Soil Clay-to-Carbon Saturation Concept

    Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl

    2012-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

  19. Clay modified crushed salt for shaft sealing elements. Material optimization and evaluation in field tests

    Glaubach, Uwe; Hofmann, Martin; Gruner, Matthias; Kudla, Wolfram [TU Bergakademie Freiberg (Germany). Inst. of Mining and Special Civil Engineering

    2015-07-01

    Salt-based materials are intended to use for backfill and sealing systems in geotechnical barriers in underground HLW-repositories. Due to the creep of the saliniferous host rock, the salt backfill will be compacted during several hundreds or thousands years of operation to a minimum of porosity resp. permeability. To raise the sealing potential of a salt-based backfill, the porosity after construction should be minimized by optimal material performance and compaction performance. A procedure to optimize the grain size distribution of crushed salt and its water and clay content is described. The optimized salt fraction gets a better compaction behavior than straight mine-run salt. The addition of a filler-like material (e.g. Friedland Clay Powder) reduces the total porosity and permeability. Backfill columns made from crushed salt and clay probably include an instant sealing function.

  20. Report on Modeling Coupled Processes in the Near Field of a Clay Repository

    Liu, Hui -Hai [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Li, Lianchong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Asahina, Daisuke [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Fei [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world. Coupled thermal, hydrological, mechanical, and chemical (THMC) processes have a significant impact on the long-term safety of a clay repository. For example, the excavation damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability. This report documents results from three R&D activities: (1) implementation and validation of constitutive relationships, (2) development of a discrete fracture network (DFN) model for investigating coupled processes in the EDZ, and (3) development of a THM model for the FE tests at Mont Terri, Switzerland, for the purpose of model validation. The overall objective of these activities is to provide an improved understanding of EDZ evolution in clay repositories and the associated coupled processes, and to develop advanced relevant modeling capabilities.

  1. ATLAS IV in situ heating test in Boom Clay

    Chen, Guangjing; Li, Xiangling; Verstricht, Jan; Sillen, Xavier

    2012-01-01

    Document available in extended abstract form only. The small scale in-situ ATLAS (Admissible Thermal Loading for Argillaceous Storage) tests are performed to assess the hydro-mechanical effects of a thermal transient on the host Boom clay at the HADES underground research facility in Mol, Belgium. The initial test set-up, consisting of a heater borehole and two observation boreholes, was installed in 1991-1992. The first test (later named 'ATLAS I') was then performed from July 1993 to June 1996; during this time, the heater dissipated a constant power of 900 W. During the second phase ('ATLAS II'), the heating power was doubled (1800 W) and maintained constant from June 1996 to May 1997. This was followed by shutdown and natural cooling starting from June 1997 on. To broaden the THM characterization of the Boom clay at a larger scale and at different temperature levels, the test set-up was extended in 2006 by drilling two additional instrumented boreholes (AT97E and AT98E). The heater was switched on again from April 2007 to April 2008 with a stepwise power increase, followed by an instantaneous shutdown. This phase is called 'ATLAS III'. The above tests have provided a large set of good quality and well documented data on temperature, pore water pressure and total stress; these data allowed to make several interesting observations regarding the thermal anisotropy and THM coupling in the Boom clay. The straightforward geometry and well defined boundary conditions of the tests facilitate the comparison between measurement and numerical modeling studies. Based on the three dimensional coupled THM modeling of the ATLAS III test, the good agreement between measurement and numerical modeling of temperature and pore water pressure yields a set of THM parameters and confirms the thermo-mechanical anisotropy of the Boom clay. To get a better insight in the anisotropic THM behavior of the Boom clay, a new upward instrumented borehole was drilled above the ATLAS heater at

  2. Interpretation of reflection seismics in the area North of Laegeren - Zurich Weinland

    Naef, H.; Birkhaeuser, P.; Roth, P.

    1995-05-01

    The investigations of potential siting areas for a repository for high-level radioactive waste which are concentrated in the crystalline basement of Northern Switzerland have been expanded since the late 1980s to include suitable sedimentary units. After extensive desk study evaluation, the approximately 100 m thick Opalinus Clay of the Tabular Jura east of the Aare river was chosen as the most promising sedimentary option. In this area not only the Opalinus Clay but also the over- and underlying units are clay-rich, in contrast to the tabular Jura west of the Aare river. In the area North of Laegeren - Zurich Weinland, where the Opalinus Clay is situated in the optimum depth range of 400 to 1000 m below surface, approximately 220 km of new high-resolution seismic profiles were recorded and interpreted together with existing seismic lines. Due to thorough field work and data processing, a very good quality of seismic lines was obtained. This allowed precise mapping of the marker horizons in general and the Opalinus Clay in detail. The goal of this study was to determine and delineate the most important tectonic units as well as to describe the potential host rocks in these units. By way of interactive interpretation of all available seismic lines, borehole data and surface data from the investigation area, depth maps of the most prominent marker horizons have been calculated and geological cross-sections constructed along the new seismic lines. The regional seismic character of the Middle Mesozoic units was modelled using borehole data from Weiach and Herdern. From this model the thickness of the Opalinus Clay along the new seismic lines was determined. The results indicate a relatively constant thickness of 95 to 120 m in the investigation area. (author) figs., tabs., refs

  3. Compressibility characteristics of Sabak Bernam Marine Clay

    Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

    2018-04-01

    This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

  4. Sorption of radionuclides by tertiary clays

    Wagner, J.F.; Czurda, K.A.

    1990-01-01

    The sorption capacity of different clay types for some metals (Co, Cs, Sr and Zn), occurring as common radionuclides in radioactive waste deposits, had been analysed by a static (batch technique) and a dynamic method (percolation tests, in which the driving force is a hydraulic gradient). Sorption capacity generally increased with an increasing pH of solution. A decrease of sorption capacity had been observed in the order Zn > Cs ≥ Co > Sr for the batch and Cs > Zn > Sr > Co for the percolation tests. Clay marls showed a distinctly higher sorption respectively retention capacity as pure clays. Sorption capacity depends on solution parameters like type and concentration of radionuclide, pH, salt concentration, etc., and on rock parameters like mineral content (e.g. swelling clay minerals and carbonates), organic material, rock pH, micro fabric, etc. A third parameter of great influence is the contact time between clay and solution. The adsorption isotherms reflect two different adsorption mechanisms: a very rapid adsorption (a few minutes) on the external surfaces of clay minerals and a slow adsorption process (weeks and longer), due to the diffusion of metal ions into the interlayer space of clay minerals. 12 refs., 9 figs., 1 tab

  5. Iron-clay interactions under a thermal gradient

    Jodin-Caumon, Marie-Camille; Mosser-Ruck, Regine; Randi, Aurelien; Cathelineau, Michel; Michau, Nicolas

    2010-01-01

    Document available in extended abstract form only. Repository in deep geological formations is considered as a possible solution for long-term high-level nuclear waste (HLW) management. The concept generally consists in a multiple barriers system including steel canister in a clay host rock. Heat and radiation emissions by HLW, corrosion of the canister and desaturation/re-saturation of the clay may affect the properties of the geological formation. In this context, the possible mineralogical evolutions of clays in contact with metal iron were studied in various conditions simulating those of HLW repository. Most of these studies were carried out at a constant temperature whereas the system will undergo a thermal gradient in time (progressive decrease of the temperature of the HLW with the decrease of its activity) and space (from the waste to the host rock). A thermal gradient may imply mass transport phenomena by convection and diffusion processes as a function of temperature, gradient intensity and the nature of the chemical elements. Here we show the effect of a thermal gradient in space on the interaction between the argillite from the ANDRA underground laboratory at Bure (Meuse/Haute-Marne) and metal iron. Tube-in-tube experiments were carried out. Argillite was put in two previously drilled platinum capsules (Diam. holes: 200 μm). Metal iron (powder and plate) was added in one of the Pt capsule. The Pt capsules were then loaded at the two ends of a gold tube. A fluid (H 2 O or a saline solution) was added and the gold tube was sealed and regularly pinched to form 5 precipitation niches. The iron/argillite mass ratio ranged between 0.3 and 0.5 and the fluid/argillite mass ratio was around 10. A thermal gradient 80 deg. C-150 deg. C or 150 deg. C-300 deg. C was applied to the tube during 3 and 6 months. The end of the gold tube with the Pt capsule containing iron was placed at the hot point (max. temperature 150 deg. C or 300 deg. C) or at the cold point (min

  6. Corrosion of carbon steel in clay environments relevant to radioactive waste geological disposals, Mont Terri rock laboratory (Switzerland)

    Necib, S. [Agence Nationale pour la Gestion des Déchets Radioactifs ANDRA, Meuse Haute-Marne, Center RD 960, Bure (France); Diomidis, N. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); Keech, P. [Nuclear Waste Management Organisation NWMO, Toronto (Canada); Nakayama, M. [Japan Atomic Energy Agency JAEA, Horonobe-Cho (Japan)

    2017-04-15

    Carbon steel is widely considered as a candidate material for the construction of spent fuel and high-level waste disposal canisters. In order to investigate corrosion processes representative of the long term evolution of deep geological repositories, two in situ experiments are being conducted in the Mont Terri rock laboratory. The iron corrosion (IC) experiment, aims to measure the evolution of the instantaneous corrosion rate of carbon steel in contact with Opalinus Clay as a function of time, by using electrochemical impedance spectroscopy measurements. The Iron Corrosion in Bentonite (IC-A) experiment intends to determine the evolution of the average corrosion rate of carbon steel in contact with bentonite of different densities, by using gravimetric and surface analysis measurements, post exposure. Both experiments investigate the effect of microbial activity on corrosion. In the IC experiment, carbon steel showed a gradual decrease of the corrosion rate over a period of 7 years, which is consistent with the ongoing formation of protective corrosion products. Corrosion product layers composed of magnetite, mackinawite, hydroxychloride and siderite with some traces of oxidising species such as goethite were identified on the steel surface. Microbial investigations revealed thermophilic bacteria (sulphate and thiosulphate reducing bacteria) at the metal surface in low concentrations. In the IC-A experiment, carbon steel samples in direct contact with bentonite exhibited corrosion rates in the range of 2 µm/year after 20 months of exposure, in agreement with measurements in absence of microbes. Microstructural and chemical characterisation of the samples identified a complex corrosion product consisting mainly of magnetite. Microbial investigations confirmed the limited viability of microbes in highly compacted bentonite. (authors)

  7. Deformation and Fabric in Compacted Clay Soils

    Wensrich, C. M.; Pineda, J.; Luzin, V.; Suwal, L.; Kisi, E. H.; Allameh-Haery, H.

    2018-05-01

    Hydromechanical anisotropy of clay soils in response to deformation or deposition history is related to the micromechanics of platelike clay particles and their orientations. In this article, we examine the relationship between microstructure, deformation, and moisture content in kaolin clay using a technique based on neutron scattering. This technique allows for the direct characterization of microstructure within representative samples using traditional measures such as orientation density and soil fabric tensor. From this information, evidence for a simple relationship between components of the deviatoric strain tensor and the deviatoric fabric tensor emerge. This relationship may provide a physical basis for future anisotropic constitutive models based on the micromechanics of these materials.

  8. Synthetic mullite fabrication from smectite clays

    Lima, L.N. de; Kiminami, R.H.G.A.

    1988-01-01

    The technological importance of mullite is mostly due to its refractory properties. Mullite in native form is very rare, and therefore it may be necessary to produced it by synthetic means. Brazil has a large reserve of smectite clays. In this work the process to produce synthetic mullite from these clays by treatment with aluminum sulphate was studied. X-ray analyses has shown the presence of mullite crystals in treated smectite clays of several colours, sinterized at 1100 0 C. By sintering at 1300 0 C, pure mullite was obtained in some colours. (author) [pt

  9. Discrete analysis of clay layer tensile strength

    Le, T.N.H.; Ple, O.; Villard, P.; Gourc, J.P.

    2010-01-01

    The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover and comparing to experimental large scale field bending tests achieved in a real site of storage. (authors)

  10. Influence of natural mobile organic matter on europium retention on Bure clay rock

    Vu-Do, Laurence

    2013-01-01

    Bure clay rock (CR) was chosen as host rock for the French high and intermediate level long lived radioactive waste repository. This choice is mostly explained by the retention ability of the Callovo-Oxfordian rock (COx). Bure clay rock contains natural organic matter (OM) that could have an influence on radionuclide retention. The aim of this work is to assess the influence of natural mobile OM on the retention of Eu on clay rock. Eu was chosen as a chemical model for trivalent actinides contained in vitrified waste. Three organic molecules were studied: suberic, sorbic and tiglic acids, small organic acids identified in COx pore water. All the experiments were carried out in an environment recreating COx water (pH=7.5; I=0.1 mol/L; PCO 2 =10 -2 bar).Clay rock sample characterization showed that the sample used in this work was similar to those previously extracted from the area of interest and that it was necessary to maintain pH at 7.5 to avoid altering the clay rock. The Eu-OM system study indicated that organic acids had no influence on Eu speciation in COx water. The Eu-CR system experimental study confirmed that retention implied sorption on CR (C(Eu)≤6.10 -6 mol/L) and precipitation in COx water (C(Eu)≥6.10 -6 mol/L). Distribution coefficient Rd (quantifying sorption) was estimated at 170 ± 30 L/g. This high value is consistent with literature values obtained on clay rocks. The ternary Eu-OM-CR system study showed a slight increase of sorption in the presence of organic matter. This synergistic effect is very satisfactory in terms of storage security: the presence of small organic acids in clay rock does not question retention properties with respect to europium and trivalent actinides. (author)

  11. Hollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone

    François, Bertrand; Labiouse, Vincent; Dizier, Arnaud; Marinelli, Ferdinando; Charlier, Robert; Collin, Frédéric

    2014-01-01

    Boom Clay is extensively studied as a potential candidate to host underground nuclear waste disposal in Belgium. To guarantee the safety of such a disposal, the mechanical behaviour of the clay during gallery excavation must be properly predicted. In that purpose, a hollow cylinder experiment on Boom Clay has been designed to reproduce, in a small-scale test, the Excavation Damaged Zone (EDZ) as experienced during the excavation of a disposal gallery in the underground. In this article, the focus is made on the hydro-mechanical constitutive interpretation of the displacement (experimentally obtained by medium resolution X-ray tomography scanning). The coupled hydro-mechanical response of Boom Clay in this experiment is addressed through finite element computations with a constitutive model including strain hardening/softening, elastic and plastic cross-anisotropy and a regularization method for the modelling of strain localization processes. The obtained results evidence the directional dependency of the mechanical response of the clay. The softening behaviour induces transient strain localization processes, addressed through a hydro-mechanical second grade model. The shape of the obtained damaged zone is clearly affected by the anisotropy of the materials, evidencing an eye-shaped EDZ. The modelling results agree with experiments not only qualitatively (in terms of the shape of the induced damaged zone), but also quantitatively (for the obtained displacement in three particular radial directions).

  12. R and D programme on radioactive waste disposal into geological formations (study of a clay formation)

    Centre d'Etude de l'Energie Nucleaire, Mol

    1987-01-01

    This report deals with the R and D activities performed by the Belgian Nuclear Research Establishment (SCK/CEN) and its subcontractors concerning the disposal of high-level and long-life conditioned wastes in a deep clay formation, the Boom clay. The studies reported concern equally experimental as theoretical work spread over the following research issues: geochemical characterization of the Boom clay, modelling of radionuclide migration in the clay environment, irradiation effects and corrosion behaviour of candidate canister materials in the Boom clay, geomechanical, construction, backfilling and sealing studies related to underground facilities, regional hydrological investigations of the Mol site and safety and risk analysis. The geomechanical and construction-related studies are to a large extent focused on in situ research, performed along the construction of the underground Hades laboratory. The corrosion studies are also dealing with the preparation of in situ experiments in the same underground laboratory. These various research issues are meant to contribute to the assessment of the technical feasibility and safety of the geological disposal in an argillaceous host formation

  13. Geochemical study of evaporite and clay mineral-oxyhydroxide samples from the Waste Isolation Pilot Plant site

    Brookins, D.G.

    1993-06-01

    Samples of clay minerals, insoluble oxyhydroxides, and their host evaporites from the WIPP site have been studied for their major and minor elements abundances, x-ray diffraction characteristics, K-Ar ages, and Rb-Sr ages. This study was undertaken to determine their overall geochemical characteristics and to investigate possible interactions between evaporates and insoluble constituents. The evaporite host material is water-soluble, having Cl/Br ratios typical of marine evaporites, although the Br content is low. Insoluble material (usually a mixture of clay minerals and oxyhydroxide phases) yields very high Cl/Br ratios, possibly because of Cl from admixed halide minerals. This same material yields K/Rb and Th/U ratios in the normal range for shales; suggesting little, if any, effect of evaporite-induced remobilization of U, K, or Rb in the insoluble material. The rare-earth element (REE) data also show normal REE/chondrite (REE/CHON) distribution patterns, supporting the K/Rb and Th/U data. Clay minerals yield K-Ar dates in the range 365 to 390 Ma and a Rb-Sr isochron age of 428 ± 7 Ma. These ages are well in excess of the 220- to 230-Ma formational age of the evaporites, and confirm the detrital origin of the clays. The ages also show that any evaporite or clay mineral reactions that might have occurred at or near the time of sedimentation and diagenesis were not sufficient to reset the K-Ar and Rb-Sr systematics of the clay minerals. Further, x-ray data indicate a normal evaporitic assemblage of clay minerals and Fe-rich oxyhydroxide phases. The clay minerals and other insoluble material appear to be resistant to the destructive effects of their entrapment in the evaporites, which suggests that these insoluble materials would be good getters for any radionuclides (hypothetically) released from the storage of radioactive wastes in the area

  14. Evaluation of Used Fuel Disposition in Clay-Bearing Rock

    Jove-Colon, Carlos F.; Weck, Philippe F.; Sassani, David Carl; Zheng, Liange; Rutqvist, Jonny; Steefel, Carl I.; Kim, Kuhhwi; Nakagawa, Seiji; Houseworth, James; Birkholzer, Jens T.; Caporuscio, Florie Andre; Cheshire, Michael; Rearick, Michael; McCarney, Mary K.; Zavarin, Mavrik; Benedicto, Ana; Kersting, Annie B.; Sutton, Mark.; Jerden, James L.; Frey, Kurt E.; Copple, Jacqueline M.; Ebert, William L.

    2014-08-01

    Radioactive waste disposal in shale/argillite rock formations has been widely considered given its desirable isolation properties (low permeability), geochemically reduced conditions, anomalous groundwater pressures, and widespread geologic occurrence. Clay/shale rock formations are characterized by their high content of clay minerals such as smectites and illites where diffusive transport and chemisorption phenomena predominate. These, in addition to low permeability, are key attributes of shale to impede radionuclide mobility. Shale host-media has been comprehensively studied in international nuclear waste repository programs as part of underground research laboratories (URLs) programs in Switzerland, France, Belgium, and Japan. These investigations, in some cases a decade or more long, have produced a large but fundamental body of information spanning from site characterization data (geological, hydrogeological, geochemical, geomechanical) to controlled experiments on the engineered barrier system (EBS) (barrier clay and seals materials). Evaluation of nuclear waste disposal in shale formations in the USA was conducted in the late 70’s and mid 80’s. Most of these studies evaluated the potential for shale to host a nuclear waste repository but not at the programmatic level of URLs in international repository programs. This report covers various R&D work and capabilities relevant to disposal of heat-generating nuclear waste in shale/argillite media. Integration and cross-fertilization of these capabilities will be utilized in the development and implementation of the shale/argillite reference case planned for FY15. Disposal R&D activities under the UFDC in the past few years have produced state-of-the-art modeling capabilities for coupled Thermal-Hydrological-Mechanical-Chemical (THMC), used fuel degradation (source term), and thermodynamic modeling and database development to evaluate generic disposal concepts. The THMC models have been developed for shale

  15. Geo scientific basis for making the safety case for a SF/HL W/IL W repository in Opalinus clay in ne Switzerland (project Entsorgungsnachweis) 1: overview and main conclusions

    Gautschi, A.; Lambert, A.; Zuidema, P.

    2004-01-01

    This paper provides an overview of the geo-scientific basis and the main conclusions concerning the safety case for Project Entsorgungsnachweis (Nagra, 2002a, see first paper). The key geo-scientific input for the safety case is summarised in the following three papers. The data and arguments are discussed in great detail in Nagra (2002b) and in numerous reference reports cited therein. (author)

  16. Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

    Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

    2018-03-01

    Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Diffusion through statically compacted clay

    Ho, C.L.; Shebl, M.A.A.

    1994-01-01

    This paper presents experimental work on the effect of compaction on contaminant flow through clay liners. The experimental program included evaluation of soil properties, compaction, permeability and solute diffusion. A permeameter was built of non reactive materials to test samples compacted at different water contents and compactive efforts. The flow of a permeating solute, LiCl, was monitored. Effluent samples were collected for solute concentration measurements. The concentrations were measured by performing atomic adsorption tests. The analyzed results showed different diffusion characteristics when compaction conditions changed. At each compactive effort, permeability decreased as molding water content increased. Consequently, transit time (measured at relative concentration 50%) increased and diffusivity decreased. As compactive effort increased for soils compacted dry of optimum, permeability and diffusion decreased. On the other hand, as compactive effort increased for soils compacted wet of optimum, permeability and diffusivity increased. Tortuosity factor was indirectly measured from the diffusion and retardation rate. Tortuosity factor also decreased as placement water content was increased from dry of optimum to wet of optimum. Then decreases were more pronounced for low compactive effort tests. 27 refs., 7 figs., 5 tabs

  18. Fracture in Kaolinite clay suspensions

    Kosgodagan Acharige, Sebastien; Jerolmack, Douglas J.; Arratia, Paulo E.

    2017-11-01

    Clay minerals are involved in many natural (landslides, river channels) and industrial processes (ceramics, cosmetics, oil recovery). They are plate shaped charged colloids and exhibit different flow properties than simpler colloids when suspended in a liquid such as thixotropy and shear-banding. kaolinite platelets are non-swelling, meaning that the stacks formed by the platelets do not have water layers, and thus the suspension does not have a sol-gel transition. However, it has been shown that kaolinite suspensions possesses a non-zero yield stress even at low concentrations, indicating that the particles arrange themselves in a structure through attractive interactions. Here, we experimentally investigate the sedimentation of kaolinite suspensions in a Hele-Shaw cell. The sedimentation of these dilute suspensions can display solid behavior like fracture, revealed in cross-polarized light, which is linked to the failure of the weakly-bonded structure (typical yield stress 10-2 Pa). By changing the interaction potential of the particles (by sonication or introducing salts), we show through these sedimentation experiments, how the fracture pattern can be avoided. Research was sponsored by the Army Research Laboratory and was accomplished under Grant Number 569074.

  19. Clay-free drilling mud

    Akhmadeyev, R G; Panov, V B; Simonenkov, O I

    1982-01-01

    A clay-free drilling mud is proposed which contains humate-containing substance, alkali electrolyte, gel-former, inhibitor and water. In order to reduce viscosity of the static shear stress and water output under conditions of polyvalent aggression, it additionally contains organic stabilizer with the following ratio of components, % by mass: humate-containing substance 4.0-8.0; alkali electrolyte 0.2-1.5; gel-former 1.0-3.0; organic stabilizer 0.1-1.0; inhibitor 1.0-40.0; water--the rest. The solution is also distinguished by the fact that the gel-former used is magnesium chloride or magnesium sulfate, or calcium chloride or aluminum sulfate, or iron chloride (III) or iron sulfate (II) or waste of chlorides of titanium production with average chemical composition, % by mass: Ti 1.5-7.0; Fe 5.0-15.0; Al 1.5-10.0; Na 5.0-16.0; Mg 0.5-3.0; Cl 30.0-60.0; Ca 0.2-2.0; Cr 0.2-2.0; Cu 0.2-1.5.

  20. Radionuclides sorption in clay soils

    Siraky, G.; Lewis, C.; Hamlat, S.; Nollmann, C.E.

    1987-01-01

    The sorption behaviour of clay soils is examined through a parametric study of the distribution coefficient (Kd) for the radionuclides of interest, Cs and Sr. This work is a preliminary stage of the migration studies of these nuclides in a porous medium (ground of Ezeiza, Argentina) and the evaluation of radiologic impact of the removal of low and intermediate activity wastes in shallow trenches. The determination of Kd is performed by a static technique or batch. The phases are separated by centrifugation at 20000 g during 1 hour. The activity of supernatant solution of Cs-137 and Sr-85 is measured in a detecting system of I Na(Tl) well-type. Two types of parameters were changed: a) those related to the determination method: phase separation (centrifugation vs. centrifugation plus filtration); equilibrium period, ratio solid/liquid; b) those related to the geochemical system: pH of contact solution, carrier concentration, competitive ions, ionic strength, desorption. It was observed that the modification of parameters in the Kd-measurement does not change the order of magnitude of results. (Author)

  1. Thermally modified bentonite clay for copper removal

    Bertagnolli, C.; Kleinübing, S.J.; Silva, M.G.C.

    2011-01-01

    Bentonite clay coming from Pernambuco was thermally modified in order to increase its affinity and capacity in the copper removal in porous bed. The application of this procedure is justified by the low cost of clay, their abundance and affinity for various metal ions. Thermally treatment modifies the clay adsorption properties enables its use in porous bed system, with the increase in surface area and mechanical strength. The material was characterized by x-ray diffraction, thermogravimetric analysis and N_2 physisorption. Then tests were carried out for adsorption of copper in various experimental conditions and evaluated the mass transfer zone, useful and total adsorbed removal amounts and total copper removal percentage. The results showed that the clay treated at higher temperature showed higher copper removal. (author)

  2. Geochemical and mineralogical characteristics of Lithomargic clay

    Administrator

    Geochemical and mineralogical characteristics of Lithomargic clay. GEOCHEMICAL AND .... tries, as filling material in the pulp and paper, toothpaste and paint industries as well ..... tions very vital to human health and other ac- tivities of man.

  3. Study of radionuclide migration in clay formations

    Antonioli, F.; Bocola, W.

    1985-01-01

    This paper reports the studies on the migration of Cs, Sr and I in clay formations, which are presently considered for the geological disposal of radioactive wastes. The distribution and diffusion coefficients were evaluated by means of experimental techniques and computer procedures, which are presented in this report. The natural clays tested in the laboratory experiments were sampled from the most representative italian basins and from the zone of Mol (Belgium). In addition tests were performed on monomineral clays artificially remade in edometer. The experimental results are in accordance with data found in the literature and show the existence of a good correlation between the observed migration properties and the granulometric and mineralogic characteristics of the natural clays

  4. pillared and un-pillared bentonite clays

    BARTH EKWUEME

    2011-07-29

    Jul 29, 2011 ... A pseudo-second order kinetic model was used to characterize the metal ion transport ... may endanger human health through consumption of sea food and ... widely reported. The pillared clays are two – dimensional zeolite.

  5. experimental characterization of clay soils behavior stabilized

    S. Rehab Bekkouche, G. Boukhatem

    2016-09-01

    Sep 1, 2016 ... California Bearing Ratio (CBR) ... the globe. Clay soils have the curious property of seeing their consistency changes according ... The use of building materials had been popularly applied to soil stabilization, such as cement.

  6. Aspects of clay/concrete interactions

    Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

    1997-01-01

    In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

  7. Possibility of disposing of conditioned nuclear waste in deep-lying clay formations

    Bonne, A.; Heremans, R.; Vandenberghe, N.

    1980-01-01

    Among the host rock types suitable for final disposal of nuclear waste, argillaceous formations display distinct advantages and disadvantages. In the present paper some of them will be examined. In order to render conceivable the possibilities for disposing of radwastes into a plastic clay formation, some main items of the Belgian R and D-programme in that matter will be discussed (site and rock investigation, conceptual design and feasibility, and risk analysis). (Auth.)

  8. Backfilling and sealing of repositories and access shafts and galleries in clay, granite and salt formations

    Lake, L.M.; Davies, I.L.; Gera, F.; Jorda, M.; McEwen, T.; Neerdael, B.; Schmidt, M.W.

    1985-01-01

    The paper summarizes the work carried out under ten Commission contracts in the field of backfilling and sealing radioactive waste repositories. It covers theoretical, laboratory and field trials and experiments involving three potential host types, namely clay, salt and hard rock. It concludes that maximum opportunity should be taken over the next 15 to 25 years with a view to obtaining first hand experience in real ground with real wastes

  9. Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    2013-01-01

    Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...... sandstones....

  10. Pedological ~cterization, Clay Mine:at~ and .~cation of,

    namely, very deep, well drained, dark reddish brown to dark brown, sandy clay loams and sandy clays on the steep convex slopes; very deep, well drained, dark brown to dark red, sandy clay loams and; sandy clays on the linear slopes; and very ...

  11. Utilization of Nkpuma-Akpatakpa clay in ceramics: characterization ...

    Nkpuma – Akpatakpa clay was analysed for its ceramics suitability. Chemical, mechanical and spectral characterization of the clay was carried out to obtain more information from this clay found in commercial quantity at Ebonyi State Nigeria. The XRD analysis showed that the principal minerals in the clay are quartz, ...

  12. Preparation and properties of recycled HDPE/clay hybrids

    Yong Lei; Qinglin Wu; Craig M. Clemons

    2007-01-01

    Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

  13. The Composition and Physical Properties of Some Clays of Cross ...

    ... and quartz as the main subsidiary non-clay mineral. The high plasticity index of the clays corresponds to the more transported clays of the tertiary- to –recent environment. The percentage of linear shrinkage varied from 11-16% with the lowest shrinkage (11%), having the coarsest features. Silica (SiO2) content of the clays ...

  14. Preparation and characterization of nano gold supported over montmorillonite clays

    Suraja, P.V.; Binitha, N.N.; Yaakob, Z.; Silija, P.P.

    2009-01-01

    Full text: The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl 4 ·3H 2 O by deposition-precipitation (DP) methods. However, it is difficult to prepare nano scale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. Here there is no need of increasing the pH of the solution to reduce the Au 3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-Vis Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method. (author)

  15. Preparation and Characterization of Nano Gold Supported over Montmorillonite Clays

    Suraja, P V; Binitha, N N; Yaakob, Z; Silija, P P, E-mail: binithann@yahoo.co.in [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2011-02-15

    The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl4{center_dot}3H2O by deposition-precipitation (DP) methods. However, it is difficult to prepare nanoscale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. There is no need of increasing the pH of the solution to reduce the Au3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-VIS Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method.

  16. What Makes a Natural Clay Antibacterial?

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

  17. Quality evaluation of processed clay soil samples.

    Steiner-Asiedu, Matilda; Harrison, Obed Akwaa; Vuvor, Frederick; Tano-Debrah, Kwaku

    2016-01-01

    This study assessed the microbial quality of clay samples sold on two of the major Ghanaian markets. The study was a cross-sectional assessing the evaluation of processed clay and effects it has on the nutrition of the consumers in the political capital town of Ghana. The items for the examination was processed clay soil samples. Staphylococcus spp and fecal coliforms including Klebsiella, Escherichia, and Shigella and Enterobacterspp were isolated from the clay samples. Samples from the Kaneshie market in Accra recorded the highest total viable counts 6.5 Log cfu/g and Staphylococcal count 5.8 Log cfu/g. For fecal coliforms, Madina market samples had the highest count 6.5 Log cfu/g and also recorded the highest levels of yeast and mould. For Koforidua, total viable count was highest in the samples from the Zongo market 6.3 Log cfu/g. Central market samples had the highest count of fecal coliforms 4.6 Log cfu/g and yeasts and moulds 6.5 Log cfu/g. "Small" market recorded the highest staphylococcal count 6.2 Log cfu/g. The water activity of the clay samples were low, and ranged between 0.65±0.01 and 0.66±0.00 for samples collected from Koforidua and Accra respectively. The clay samples were found to contain Klebsiella spp. Escherichia, Enterobacter, Shigella spp. staphylococcus spp., yeast and mould. These have health implications when consumed.

  18. Soil clay content underlies prion infection odds

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  19. Characterization of clay used for red ceramic fabrication

    Pereira, P.S.; Morais, A.S.C.; Caldas, T.C.C.; Monteiro, S.N.; Vieira, C.M.F.

    2011-01-01

    The objective of this work is to characterize a clay used in the red ceramics fabrication, from Campos dos Goytacazes north of the State of Rio de Janeiro. The clay was submitted for physical, chemical and mineralogical tests. The results showed that the clay has a high content of clay minerals with kaolinitic predominance, high loss on ignition and low flux oxides. It is recommended that this clay is mixed with non-plastic materials. (author)

  20. Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

    Tsai, Tsung-Yen; Lin, Mei-Ju; Chuang, Yi-Chen; Chou, Po-Chiang

    2013-01-01

    The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O 2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites. - Highlights: ► We control the dispersion morphology by protonation of K2 into the clay. ► The CL120 and CL88, with the higher CEC, are more random intercalated by K2. ► We report these materials have good optical clarity, and UV resistance

  1. Water retention properties of Callovo-Oxfordian clay-stone

    Wan, Min; Delage, Pierre; Tang, Anh Minh; GATMIRI, Behrouz

    2012-01-01

    Document available in extended abstract form only. Many investigations were carried out on the Callovo-Oxfordian (COx) clay-stone that has been selected by the French radioactive waste management agency (ANDRA) as a potential host rock for high level radioactive waste disposal at great depth. Various authors demonstrated the significant water sensitivity of clay-stones. Some cracks generated by desaturation have been observed in the Tournemire URL (France) excavated in clay-stone. By carrying out some ESEM (environmental scanning electron microscope) observations on COx clay-stone samples submitted to cyclic changes in relative humidity, Montes et al. (2004) evidenced the water sensitivity of the clay fraction, with significant successive openings and closures of cracks and pores. Hysteresis effects have been observed in the water retention curve, in the ultrasonic velocity evolution and in the strain changes induced by hydration cycles on COx samples submitted to controlled relative humidities by Pham et al., (2007). Better knowledge of the mechanism of desaturation of the clay-stone is necessary to further understand the changes in hydro-mechanical properties of the excavation damaged zone (EDZ) that becomes significantly de-saturated all around the galleries because of ventilation. In this framework, a detailed study of the water retention properties of the COx clay-stone was carried out i) to complete existing observations with respect to volume changes under suction cycles and ii) to determine the main drying and wetting curves so as to better investigate hysteresis effects in the water retention curve.. Particular attention was paid to the characterization of the initial state in the laboratory (where samples are provided unsaturated due to the combined effect of coring, storage and transportation) and to the volume changes and changes in degree of saturation along the main wetting and drying paths. The determination of the water retention properties was

  2. Silt-clay aggregates on Mars

    Greeley, R.

    1979-01-01

    Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition, and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles. Electrification is proposed to occur within Martian dust clouds, generating silt-clay aggregates which would settle to the surface where they may be deposited in the form of sandlike structures. By analog, silt-clay dunes are known in many parts of the earth where silt-clay aggregated were transported by saltation and deposited as 'sand.' In these structures the binding forces were later destroyed, and the particles reassumed the physical properties of silt and clay, but the sandlike bedding structure within the 'dunes' was preserved. The bedding observed in drifts at the Viking landing site is suggested to result from a similar process involving silt-clay aggregates on Mars

  3. Laboratory hydro-mechanical characterisation of Boom Clay at Essen and Mol

    Deng, Y. F.; Tang, A. M.; Cui, Y. J.; Nguyen, X. P.; Li, X. L.; Wouters, L.

    2011-01-01

    Boom Clay has been selected as a potential host rock formation for the geological disposal of radioactive waste in Belgium. In the present work, the hydro-mechanical behaviour of Boom Clay samples from the borehole Essen-1 at a depth of 220-260 m and from HADES that is the underground rock laboratory at Mol in Belgium, at 223-m depth was investigated in the laboratory by performing low pressure odometer tests (vertical effective stress ranging from 0.05 to 3.2 MPa), high pressure odometer tests (vertical effective stress ranging from 0.125 to 32 MPa), isotropic consolidation tests (confining effective stress ranging from the in situ stress to 20 MPa) and triaxial shear tests. It has been observed that the mineralogy, geotechnical properties and hydro-mechanical behaviour of Boom Clay from Essen at 227-m, 240-m and 248-m depths are similar to that of Boom Clay from Mol. As in the case of Boom Clay at Mol, the failure envelope of Boom Clay at Essen in the p'- q plane is not linear. The slope of the portion beyond the pre-consolidation stress of Boom Clay from Essen is almost the same as that from Mol, suggesting a similar internal friction angle of about 13 deg. The compression curves (void index I v versus logarithm of vertical stress) beyond the pre-consolidation stress are the same for both samples from Mol and Essen, and situated between the intrinsic compression line (ICL) and the sedimentation compression line (SCL). The yield stress determined from odometer tests seems to be stress-path dependent and lower than the pre-consolidation stress. Thus determining the over-consolidation ratio (OCR) using the yield stress value would lead to an incorrect estimate. From a practical point view, the laboratory test results from Essen and their comparison with those from Mol provide important information regarding the transferability of knowledge on Boom Clay at different sites, taking into account the fact that most investigations have been carried out on Boom Clay at

  4. Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

    Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

    2017-08-11

    Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

  5. Mechanical interaction between swelling compacted clay and fractured rock, and the leaching of clay colloids

    Grindrod, P.; Peletier, M.A.; Takase, H.

    1999-01-01

    We consider the interaction between a saturated clay buffer layer and a fractured crystalline rock engineered disturbed zone. Once saturated, the clay extrudes into the available rock fractures, behaving as a compressible non-Newtonian fluid. We discuss the modelling implications of published

  6. Experimental study of thermo-hydro-mechanical behaviour of Callovo-Oxfordian Clay-stone

    Mohajerani, M.

    2011-01-01

    During the different phases of the exothermic radioactive waste deep disposal (excavation, operation) and after permanent closure, the host rock is submitted to various coupled mechanical, hydraulic and thermal phenomena. Hence, a thorough investigation of the thermo-hydro-mechanical behaviour of the rock is necessary to complete existing data and to better understand and model the short and long term behaviour of the Callovo-Oxfordian (COx) clay formation in Bure (Meuse/Haute-Marne - M/HM), considered by ANDRA as a potential host rock in France.In this work, the compression - swelling behaviour of the COx Clay-stone was first investigated by carrying out a series of high-pressure oedometric tests. The results, interpreted in terms of coupling between damage and swelling, showed that the magnitude of swelling was linked to the density of the fissures created during compression. In a second step, the hydro-mechanical and thermo-hydro-mechanical behaviour of the saturated Clay-stone under a mean stress close to the in situ one were investigated by using two devices with short drainage path (10 mm), namely a isotropic cell and a newly designed hollow cylinder triaxial cell with local displacement measurements. These devices helped to solve two majors problems related to testing very low permeability materials: i) a satisfactory previous sample saturation (indicated by good Skempton values) and ii) satisfactory drainage conditions. Some typical constitutive parameters (Skempton and Biot's coefficients, drained and undrained compressibility coefficients) have been determined at ambient temperature through isotropic compression tests that also confirmed the transverse isotropy of the Clay-stone. The consistency of the obtained parameters has been checked in a saturated poro-elastic framework. Two aspects of the thermo-hydro-mechanical behaviour of the COx Clay-stone have then been investigated through different heating tests and through drained and undrained isotropic

  7. Clay Mineralogy of AN Alluvial Aquifer in a Mountainous, Semiarid Terrain, AN Example from Rifle, Colorado

    Elliott, W. C.; Lim, D.; Zaunbrecher, L. K.; Pickering, R. A.; Williams, K. H.; Navarre-Sitchler, A.; Long, P. E.; Noel, V.; Bargar, J.; Qafoku, N. P.

    2015-12-01

    Alluvial sediments deposited along the Colorado River corridor in the semi-arid regions of central to western Colorado can be important hosts for legacy contamination including U, V, As and Se. These alluvial sediments host aquifers which are thought to provide important "hot spots" and "hot moments" for microbiological activity controlling organic carbon processing and fluxes in the subsurface. Relatively little is known about the clay mineralogy of these alluvial aquifers and the parent alluvial sediments in spite of the fact that they commonly include lenses of silt-clay materials. These lenses are typically more reduced than coarser grained materials, but zones of reduced and more oxidized materials are present in these alluvial aquifer sediments. The clay mineralogy of the non-reduced parent alluvial sediments of the alluvial aquifer located in Rifle, CO (USA) is composed of chlorite, smectite, illite, kaolinite and quartz. The clay mineralogy of non-reduced fine-grained materials at Rifle are composed of the same suite of minerals found in the sediments plus a vermiculite-smectite intergrade that occurs near the bottom of the aquifer near the top of the Wasatch Formation. The clay mineral assemblages of the system reflect the mineralogically immature character of the source sediments. These assemblages are consistent with sediments and soils that formed in a moderately low rainfall climate and suggestive of minimal transport of the alluvial sediments from their source areas. Chlorite, smectite, smectite-vermiculite intergrade, and illite are the likely phases involved in the sorption of organic carbon and related microbial redox transformations of metals in these sediments. Both the occurrence and abundance of chlorite, smectite-vermiculite, illite and smectite can therefore exert an important control on the contaminant fluxes and are important determinants of biogeofacies in mountainous, semiarid terrains.

  8. Hydrogen isotope ratios of clay minerals constituting clay veins found in granitic rocks in Hiroshima Prefecture

    Kitagawa, Ryuji; Kakitani, Satoru; Kuroda, Yoshimatsu; Matsuo, Sadao; Suzuoki, Tetsuro.

    1980-01-01

    The deuterium content of the constitutional and interlayer water extracted from the clay minerals (illite, montmorillonite, interstratified illite-montmorillonite mineral, kaolinite, halloysite) constituting the clay veins found in the granitic rocks in Hiroshima Prefecture was measured. The clay minerals were heated at 270 deg C to extract the interlayer water, then heated to 1,400 or 1,500 deg C to extract the constitutional water. The deuterium content of the local surface water collected from sampling points was measured. In the clay veins formed along perpendicular joints, the constituent clay minerals change from lower to upper part: illite → montmorillonite → kaolinite → halloysite. The deuterium content values of the constitutional water for illite and montmorillonite were estimated to be -67 to -69% and -86 to -89%, respectively. The deuterium content values of the constitutional water for halloysite range from -68 to -80% and for kaolinite from -63 to -67%. (J.P.N.)

  9. Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

    Randall T. Cygan

    2007-06-01

    “Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

  10. Selection of the host rock for high level radioactive waste repository in China

    Jin Yuanxin; Wang Wenguang; Chen Zhangru

    2001-01-01

    The authors has briefly introduced the experiences of the host rock selection and the host rock types in other countries for high level radioactive waste repository. The potential host rocks in China are investigated. They include granite, tuff, clay, basalt, salt, and loess. The report has expounded the distributions, scale, thickness, mineral and chemical composition, construction, petrogenesis and the ages of the rock. The possibility of these rocks as the host rock has been studied. The six pieces of distribution map of potential rocks have been made up. Through the synthetical study, it is considered that granite as the host rock of high level radioactive waste repository is possible

  11. Monitoring and modelling of thermo-hydro-mechanical processes - main results of a heater experiment at the Mont Terri underground rock laboratory

    Ingeborg, G.; Alheid, H.J. [BGR - Federal Institute for Geosciences and Natural Resources, Hannover (Germany); Jockwerz, N. [Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS) - Final Repository Research Division, Braunschweig (Germany); Mayor, J.C. [ENRESA - Empresa Nacional des Residuos Radioactivos, Madrid (Spain); Garcia-Siner, J.L. [AITEMIN -Asociacion para la Investigacion y Desarrollo Industrial de los Recursos Naturales, Madrid, (Spain); Alonso, E. [CIMNE - Centre Internacional de Metodos Numerics en Ingenyeria, UPC, Barcelona (Spain); Weber, H.P. [NAGRA - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Plotze, M. [ETHZ - Swiss Federal Institute of Technology Zurich, IGT, Zurich, (Switzerland); Klubertanz, G. [COLENCO Power Engineering Ltd., Baden (Switzerland)

    2005-07-01

    The long-term safety of permanent underground repositories relies on a combination of engineered and geological barriers, so that the interactions between the barriers in response to conditions expected in a high-level waste repository need to be identified and fully understood. Co-financed by the European Community, a heater experiment was realized on a pilot plant scale at the underground laboratory in Mont Terri, Switzerland. The experiment was accompanied by an extensive programme of continuous monitoring, experimental investigations on-site as well as in laboratories, and numerical modelling of the coupled thermo-hydro-mechanical processes. Heat-producing waste was simulated by a heater element of 10 cm diameter, held at a constant surface temperature of 100 C. The heater element (length 2 m) operated in a vertical borehole of 7 m depth at 4 to 6 m depth. It was embedded in a geotechnical barrier of pre-compacted bentonite blocks (outer diameter 30 cm) that were irrigated for 35 months before the heating phase (duration 18 months) began. The host rock is a highly consolidated stiff Jurassic clay stone (Opalinus Clay). After the heating phase, the vicinity of the heater element was explored by seismic, hydraulic, and geotechnical tests to investigate if the heating had induced changes in the Opalinus Clay. Additionally, rock mechanic specimens were tested in the laboratory. Finally, the experiment was dismantled to provide laboratory specimens of post - heating buffer and host rock material. The bentonite blocks were thoroughly wetted at the time of the dismantling. The volume increase amounted to 5 to 9% and was thus below the bentonite potential. Geo-electrical measurements showed no decrease of the water content in the vicinity of the heater during the heating phase. Decreasing energy input to the heater element over time suggests hence, that the bentonite dried leading to a decrease of its thermal conductivity. Gas release during the heating period occurred

  12. Organic or organometallic template mediated clay synthesis

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  13. Accurate control testing for clay liner permeability

    Mitchell, R J

    1991-08-01

    Two series of centrifuge tests were carried out to evaluate the use of centrifuge modelling as a method of accurate control testing of clay liner permeability. The first series used a large 3 m radius geotechnical centrifuge and the second series a small 0.5 m radius machine built specifically for research on clay liners. Two permeability cells were fabricated in order to provide direct data comparisons between the two methods of permeability testing. In both cases, the centrifuge method proved to be effective and efficient, and was found to be free of both the technical difficulties and leakage risks normally associated with laboratory permeability testing of fine grained soils. Two materials were tested, a consolidated kaolin clay having an average permeability coefficient of 1.2{times}10{sup -9} m/s and a compacted illite clay having a permeability coefficient of 2.0{times}10{sup -11} m/s. Four additional tests were carried out to demonstrate that the 0.5 m radius centrifuge could be used for linear performance modelling to evaluate factors such as volumetric water content, compaction method and density, leachate compatibility and other construction effects on liner leakage. The main advantages of centrifuge testing of clay liners are rapid and accurate evaluation of hydraulic properties and realistic stress modelling for performance evaluations. 8 refs., 12 figs., 7 tabs.

  14. Radionuclide sorption studies on abyssal red clays

    Erickson, K.L.

    1979-01-01

    The radionuclide sorption properties of a widely distributed abyssal red clay are being experimentally investigated using batch equilibration techniques. This paper summarizes sorption equilibrium data obtained when 0.68 N NaCl solutions containing either Tc, U, Pu, Am or Cm were contacted with samples of the red clay and also summarizes some initial results from experiments designed to determine the relative selectivity of the clay for various nuclides. Under mildly oxidizing conditions, the sorption equilibrium distribution coefficients for technetium were essentially zero. At solution-phase nuclide concentrations on the order of 10 -6 M and less and at solution pH values of about 6.9, the distribution coefficients for plutonium were about 3 x 10 3 m1/gm and for uranium, americium, and curium were about 10 5 ml/gm or greater. However, at solution pH values of about 2.7, the distribution coefficients for each of the nuclides were greatly diminished. Initial experiments conducted in order to determine the relative selectivity of the clay for cesium, barium, and cerium, indicated that the silicate phases in the clay were selective for cesium over barium and cerium. These experiments also indicated that the hydrous oxide phases were selective for cerium over barium and for barium over cesium

  15. Se of polymers to control clay swelling

    Slobod, R L; Beiswanger, J P.G.

    1968-01-01

    The injection of water to displace oil is one of the main methods used to increase oil recovery. High injection rates are generally desired, and in some cases the flood will not be economic unless high rates are maintained. The presence of clays which swell in the presence of water offers a complication to the problem of maintaining adequate injectivity. In the course of this study it was observed that certain polymers, when present in dilute concentrations in the water, had the ability to reduce the response of these clays to fresh water. Two polymers, one an anionic and the other nonionic, were found to be very effective in controlling the clays present in Berea cores. Successful control of clay swelling was obtained by use of solutions containing as little as 1.0 ppM of polymer, but at this low concentration appreciable volumes of treating solution were required. These results suggest that some minimum amount of polymer must be adsorbed to prevent clay swelling. In Berea sandstone this minimum amount appeared to be of the order of 0.03 mg per cc of pore space. A series of tests made using 10.0 ppM polymer showed that the polymer could be made through the porous system in which 0.066 per mg of polymer was adsorbed per cc of pore space.

  16. The effect of high pH alkaline solutions on the mineral stability of the Boom Clay - Batch experiments at 60 deg. C

    Honty, M.; De Craen, M.; Wang, L.; Madejova, J.; Czimerova, A.; Pentrak, M.; Stricek, I.; Van Geet, M.

    2010-01-01

    Boom Clay is currently viewed as a reference host formation for studies on deep geological disposal of radioactive waste in Belgium. The interactions between bulk rock Boom Clay and 0.1 M KOH, 0.1 M NaOH, 0.1 M Ca(OH) 2 , young cement water and evolved cement water solutions, ranging in pH from 12.5 to 13.2, were examined as static batch experiments at 60 deg. C to simulate alkaline plume perturbations, which are expected to occur in the repository due to the presence of concrete. Both liquids and solids were investigated at specific times between 90 and 510 days in order to control the elemental budget and to search for potential mineralogical alterations. Also, the clay fraction was separated from the whole-rock Boom Clay at the end of each run and characterized for its mineralogical composition. Thereby, the importance of the mineral matrix to buffer the alkaline attack and the role of organic matter to protect clay minerals were also addressed. The results indicate that the degree of geochemical perturbation in Boom Clay is dependent on the initial pH of the applied solution together with the nature of the major cation in the reactant fluids. The higher the initial pH of the media, the stronger its interaction with Boom Clay. No major non-clay mineralogical alteration of the Boom Clay was detected, but dissolution of kaolinite, smectite and illite occurred within the studied experimental conditions. The dissolution of clays is accompanied by the decrease in the layer charge, followed by a decrease in the cation-exchange capacity. The highest TOC values coincide with the highest total elemental concentrations in the leachates, and correspondingly, the highest dissolution degree. However, no quantitative link could be established between the degree of organic matter decomposition and clay dissolution.

  17. Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

    Vernon Reynolds

    Full Text Available Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

  18. Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

    Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

  19. Behavior of clay exposed to heating

    Heremans, R.; Buyens, M.; Manfroy, P.

    1978-01-01

    In the frame of his R and D programme on geological burial of solidified radioactive waste, the C.E.N./S.C.K. undertook experimental and theoretical work on the behavior of the Boom clay against heat. The work is performed under contract with the Commission of European Communities. In a first phase a series of chemical and physical properties were determined on clay samples taken at various depths during the core boring performed on the C.E.N./S.C.K. site in 1975. In a second phase, a simulated high level waste heat source was developed and tested in view of representative heat transfer experiments into the geological formation. In parallel to the experimental work, computarized theoretical studies were undertaken aiming an evaluation of heat effect of a vitrified high level waste repository on an underground structure in clay

  20. Interaction of polymer with discotic clay particles

    Auvray, L.; Lal, J.

    1999-01-01

    Normally synthetic well defined monodisperse discotic laponite clays are known to form a gel phase at mass concentrations as low as a few percent in distilled water. Hydrosoluble polymer polyethylene oxide was added to this intriguing clay system, it was observed that it either prevents gelation or slows it down extremely depending on the polymer weight, concentration or the laponite concentration. Small Angle Neutron scattering (SANS) was used to study these systems because only by isotopic labeling can the structure of the adsorbed polymer layers be determined. The contrast variation technique is specifically used to determine separately the different partial structure factors of the clay and polymer. In this way the signal of the adsorbed chains is separated from the signal of the free chains in the dilute regime. Attempts have also been made to characterize the structure in the concentrated regime of laponite with polymer

  1. Luminescent Oxygen Gas Sensors Based on Nanometer-Thick Hybrid Films of Iridium Complexes and Clay Minerals

    Hisako Sato

    2014-01-01

    Full Text Available The use of Ir(III complexes in photo-responsive molecular devices for oxygen gas sensing is reviewed. Attention is focused on the immobilization of Ir(III complexes in organic or inorganic host materials such as polymers, silica and clays in order to enhance robustness and reliability. Our recent works on constructing nanometer-thick films comprised of cyclometalated cationic Ir(III complexes and clay minerals are described. The achievement of multi-emitting properties in response to oxygen pressure is demonstrated.

  2. Preparation of organophilic clays and polypropylene nano composites

    Lima, Martha Fogliato S.; Nascimento, Vinicius G. do; Lenz, Denise M.; Schenato, Flavia

    2011-01-01

    Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

  3. Removal of Phenol in Aqueous Solution Using Kaolin Mineral Clay

    Sayed, M.S.

    2008-01-01

    Kaolin clay were tested for phenol removal as toxic liquid waste from aqueous waste water. Several experimental conditions such as weight and particle size of clay were investigated to study batch kinetic techniques, also the ph and concentration of the phenol solution were carried out. The stability of the Langmuir adsorption model of the equilibrium data were studied for phenol sorbent clay system. Infrared spectra, thermogravimetric and differential thermal analysis techniques were used to characterize the behavior of kaolin clay and kaolin clay saturated with phenol. The results obtained showed that kaolin clay could be used successfully as an efficient sorbent material to remove phenol from aqueous solution

  4. Moessbauer firing study of Peruvian clays

    Salazar, R.; Wagner, U.; Wagner, F.E.

    1983-01-01

    In connection with work on ancient ceramics Moessbauer studies of the firing behaviour of six Peruvian clays have been performed in oxidizing and reducing atmospheres. For two clays, one of them is poor, the other one is rich in oxides, the change of the Moessbauer parameters on firing between 100 and 1350 0 C was measured in detail, both with and without preceding reduction. The minerals present at characteristic temperatures are determined by X-ray diffraction and an attempt is made to discuss the physical and chemical processes occurring in the different temperature ranges. (author)

  5. Synthetic clay excels in 90Sr removal

    Komarneni, Sridhar; Kodama, Tatsuya; Paulus, William J.; Carlson, C.

    2000-01-01

    Tests with actual ground water from Hanford site, and fundamental studies of 2Na + →Sr 2+ exchange equilibria revealed that a synthetic clay is extremely selective for 90 Sr with a high capacity for uptake. Comparative studies with existing Sr selective ion exchangers clearly revealed that the present synthetic clay exhibited the best performance for 90 Sr removal from actual ground water collected from three different locations at Hanford. This novel Sr ion sieve is expected to be useful for the decontamination of the environment after accidental release and contamination with 90 Sr. (c) 2000 Materials Research Society

  6. Quick clay and landslides of clayey soils.

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology.

  7. Effects of Different Types of Clays and Maleic Anhydride Modified Polystyrene on Polystyrene/Clay Nanocomposites

    M. Mehrabzadeh

    2013-01-01

    Full Text Available Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt% can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM and X-ray diffraction (XRD techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30% and elongation-at-break (~40% of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

  8. Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

    Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

    2005-01-01

    Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

  9. Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

    Moran, Anthony R; Hettiarachchi, Hiroshan

    2011-07-01

    Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

  10. Fracturing and Self-Healing in the Boom Clay: Evidences and Further Studies

    Bernier, Frederic

    2001-01-01

    The Boom Clay is considered as a potential host-rock for the disposal of Belgian radioactive waste. During the sinking of a new shaft to extend the underground facility HADES, an important fracturing has been evidenced around the excavation. Fracturing was already observed previously but to a lesser extent. The low support pressure imposed by the primary shaft lining, combined with the large time over which this support condition held, has favoured the decompression of the clay massif through delayed effects, and therefore the development of fracturing. In the frame of the overall performance of a radioactive waste repository, it is of prime importance to understand the fracturing process induced by excavation in Boom Clay, as well as the self-healing process. Some self-healing evidences have been observed around the HADES underground laboratory but need further investigation to be confirmed. This will be done in the SELFRAC EC project (Fractures and Self-healing within the Excavation Disturbed Zone in clays)

  11. Status of LANL investigations of temperature constraints on clay in repository environments

    Caporuscio, Florie A.; Cheshire, Michael C.; Newell, Dennis L.; McCarney, Mary Kate

    2012-01-01

    The Used Fuel Disposition (UFD) Campaign is presently evaluating various generic options for disposal of used fuel. The focus of this experimental work is to characterize and bound Engineered Barrier Systems (EBS) conditions in high heat load repositories. The UFD now has the ability to evaluate multiple EBS materials, waste containers, and rock types at higher heat loads and pressures (including deep boreholes). The geologic conditions now available to the U.S.A. and the international community for repositories include saturated and reduced water conditions, along with higher pressure and temperature (P, T) regimes. Chemical and structural changes to the clays, in either backfill/buffer or clay-rich host rock, may have significant effects on repository evolution. Reduction of smectite expansion capacity and rehydration potential due to heating could affect the isolation provided by EBS. Processes such as cementation by silica precipitation and authigenic illite could change the hydraulic and mechanical properties of clay-rich materials. Experimental studies of these repository conditions at high P,T have not been performed in the U.S. for decades and little has been done by the international community at high P,T. The experiments to be performed by LANL will focus on the importance of repository chemical and mineralogical conditions at elevated P,T conditions. This will provide input to the assessment of scientific basis for elevating the temperature limits in clay barriers.

  12. Presence and evolution of natural organic matter in the boom clay

    Van Geet, M.; Deniau, I.; Largeau, C.; Bruggeman, C.; Maes, A.; Dierckx, A.

    2004-01-01

    Because of its very low hydraulic conductivity, reducing conditions, slightly alkaline pH, high specific surface, high cation exchange capacity and high plasticity, the Boom Clay is studied as a reference host formation for the deep disposal of high-level long-lived radioactive waste (NIRAS/ONDRAF, 1989). However, Boom Clay also contains up to 5% wt. of organic matter (OM). As radionuclides can form complexes with this organic matter, a detailed characterisation and knowledge of the evolution of the organic matter is necessary. An overview of the characteristics of the organic matter present in Boom Clay is given by Van Geet et al., (2003). The solid phase OM can be up to 5%. The dissolved OM fraction is around 200 mg C per liter of Boom Clay pore water. Both kinds of OM will be discussed. Concerning the solid phase OM the focus will be on the past evolution and its possible future evolution due to a thermal stress. For the dissolved OM, the focus will be on its origin. (author)

  13. Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

    Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

    2003-03-01

    Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

  14. Mineralogy and geotechnical characteristics of some pottery clay

    Mujib Olamide ADEAGBO

    2016-12-01

    Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

  15. Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

    Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

    2009-01-01

    Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

  16. Crystallite size distribution of clay minerals from selected Serbian clay deposits

    Simić Vladimir

    2006-01-01

    Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

  17. Feasibility of using overburden clays for sealing purposes and laboratory testing of the clays

    Mann, J. (Vyzkumny Ustav pro Hnede Uhli, Most (Czechoslovakia))

    1992-03-01

    Studies properties of overburden clay from North Bohemian surface coal mines for use as sealants of industrial and household waste that will be dumped at Czechoslovak surface mine sites. Basic requirements of sealing layers are optimum compressibility and impermeability by suitable compacting. Laboratory soil mechanical tests of different clay samples were carried out using the Proctor standard tests (PCS) and the Norwegian Geonor A/S - m 45 instrument. Laboratory tests were used to select the best available clay types with optimum density and moisture content. Experimental results of laboratory tests are provided.

  18. Xenon-129 NMR study of the microporous structure of clays and pillared clays

    Tsiao, C.; Carrado, K.A.

    1990-01-01

    129 Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diameter of montmorillonite increases, for example, from 5.4 Angstrom to 8.0 Angstrom after pillaring cheto-montmorillonite with aluminum polyoxohydroxy Keggin cations. The data are consistent with X-ray powder diffraction results, which show a corresponding increase in the interlamellar gallery height from 5.6 Angstrom to 8.4 Angstrom

  19. Clays in natural and engineered barriers for radioactive waste confinement - 5. International meeting. Book of abstracts

    2012-10-01

    The purpose of this fifth international meeting is to bring again together specialists in the different disciplines related to clays and clay minerals, with scientists from organizations engaged in disposal of radioactive waste in order to evaluate the progress of the research conducted in that field. Multidisciplinary approaches including geology, mineralogy, geochemistry, rheology, physics and chemistry of clay minerals and assemblages are required in order to provide a detailed characterization of the geological host formations considered for the disposal of radioactive waste and to assess the behaviour of engineered and natural barriers when submitted to various types of perturbations induced by such facilities. The evaluation of the performances of the natural barrier as well as of the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations constitute major objectives for the experimental programs being and/or to be conducted in underground research laboratories, for interpreting the subsequent scientific results, for modelling the long-term behaviour of radioactive waste repositories and carrying out safety assessment exercises. The meeting covers all the aspects of clay characterization and behaviour considered at various times and space scales relevant to confinement of radionuclides in clay from basic phenomenological processes description, to the global understanding of the performance and safety at repository and geological scales. Special emphasis will be put on the modelling of processes occurring at the mineralogical level within the clay barriers. The topics covered by the program of the meeting are also supposed to be coherent with the general objectives proposed within the Strategic Research Agenda elaborated through the Implementing Geological Disposal of Radioactive Waste Technology Platform (IGD-TP). In this context, the meeting will also offer a particular opportunity to present the more

  20. In situ chemical osmosis experiment in the Boom Clay at the Mol underground research laboratory

    Garavito, A. M.; De Cannière, P.; Kooi, H.

    -permeability plastic formation such as the Boom Clay. The osmotic efficiency of Boom Clay is high under undisturbed chemical conditions ( σ = 0.41 at 0.014 M NaHCO 3), but rapidly decreases when the dissolved salts concentration increases ( σ = 0.07 at 0.14 M NaHCO 3). A semi-permeable membrane behaviour of the Boom Clay (high efficiencies) may be expected for the disposal of nitrate-bearing radioactive waste. However, the presently observed osmotically induced pressure is too low to have a significant mechanical impact on the host rock. Finally, the short duration of the osmosis test performed suggests that the shut-in test method used is effective for osmosis testing.

  1. Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay

    W.Z. Chen

    2017-06-01

    Full Text Available Boom Clay is one of the potential host rocks for deep geological disposal of high-level radioactive nuclear waste in Belgium. In order to investigate the mechanism of hydraulic conductivity variation under complex thermo-mechanical coupling conditions and to better understand the thermo-hydro-mechanical (THM coupling behaviour of Boom Clay, a series of permeability tests using temperature-controlled triaxial cell has been carried out on the Boom Clay samples taken from Belgian underground research laboratory (URL HADES. Due to its sedimentary nature, Boom Clay presents across-anisotropy with respect to its sub-horizontal bedding plane. Direct measurements of the vertical (Kv and horizontal (Kh hydraulic conductivities show that the hydraulic conductivity at 80 °C is about 2.4 times larger than that at room temperature (23 °C, and the hydraulic conductivity variation with temperature is basically reversible during heating–cooling cycle. The anisotropic property of Boom Clay is studied by scanning electron microscope (SEM tests, which highlight the transversely isotropic characteristics of intact Boom Clay. It is shown that the sub-horizontal bedding feature accounts for the horizontal permeability higher than the vertical one. The measured increment in hydraulic conductivity with temperature is lower than the calculated one when merely considering the changes in water kinematic viscosity and density with temperature. The nuclear magnetic resonance (NMR tests have also been carried out to investigate the impact of microstructure variation on the THM properties of clay. The results show that heating under unconstrained boundary condition will produce larger size of pores and weaken the microstructure. The discrepancy between the hydraulic conductivity experimentally measured and predicted (considering water viscosity and density changes with temperature can be attributed to the microstructural weakening effect on the thermal volume change

  2. Determination of gas diffusion coefficients in undisturbed Boom clay

    Jacops, E.; Volckaert, G.; Maes, N.; Govaerts, J.; Weetjens, E.

    2012-01-01

    Document available in extended abstract form only. The Belgian agency for radioactive waste and enriched fissile materials Ondraf/Niras presently considers Boom Clay as a potential host formation for the disposal of high-level and long-lived radioactive waste. The production of gas is unavoidable within a geological repository. Gas is produced by different mechanisms: anaerobic corrosion of metals in waste and packaging, radiolysis of water and organic materials in the waste and engineered barriers and microbial degradation of various organic wastes. Corrosion and radiolysis yield mainly hydrogen while microbial degradation leads to methane and carbon dioxide. The gas generated in the near field of a geological repository will dissolve in the pore water and is transported away from the repository by diffusion as dissolved species. If the gas generation rate is larger than the diffusive flux, the pore water will become over-saturated and a free gas phase will form. Initially, isolated gas bubbles will accumulate until a continuous gas phase is formed. As gas pressure continues to increase, discrete gas pathways may be formed by tensile fractures within the rock fabric. Consequently, this entire process may locally and at least temporarily alter the hydraulic and mechanical properties of the engineered barriers and the clay and, perhaps, their performance. Therefore it is important to assess whether or not gas production rates might exceed the diffusive gas flux. The currently available gas diffusion parameters (D eff : effective diffusion coefficient) for hydrogen in Boom Clay, obtained from the MEGAS project, and re-evaluated after lead to an estimated D eff between 1.9 10 -12 and 1.5 10 -10 m 2 /s. Sensitivity calculations showed that this uncertainty on the diffusion coefficient, combined with that on the gas source term, made it impossible to exclude the formation of a free gas phase. To reduce the uncertainty, an experimental method was developed to determine

  3. Quantitative approach on SEM images of microstructure of clay soils

    施斌; 李生林; M.Tolkachev

    1995-01-01

    The working principles of Videolab Image Processing System (VIPS), the examining methods of orientation of microstructural units of clay soils and analysing results on SEM images of some typical microstructures of clay soils using the VIPS are introduced.

  4. Hydration Phase Diagram of Clay Particles from Molecular Simulations.

    Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

    2017-11-07

    Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

  5. Radionuclide transport in clay during climate change

    Wildenborg, A.F.B.; Orlic, B.; Thimus, J.F.; De Lange, G.; De Cock, S.; De Leeuwe, C.S.; Veling, E.J.M.

    2002-01-01

    The Dutch national research programme into the feasibility of retrievable storage of radioactive waste (CORA Programme Phase I; CORA: Comité Opslag Radioactief Afval = Committee on Radioactive Waste Disposal) examined the suitability of Tertiary clay deposits for such storage. Long-term isolation –

  6. Radionuclide transport in clay during climate change

    Wildenborg, A.F.B.; Orlic, B.; Thimus, J.F.; Lange, G.de; Cock, S. de; Leeuw, C.S. de; Veling, E.J.M.

    2003-01-01

    The Dutch national research programme into the feasibility of retrievable storage of radioactive waste (CORA Programme Phase I; CORA: Comité Opslag Radioactief Afval = Committee on Radioactive Waste Disposal) examined the suitability of Tertiary clay deposts for such storage. Long-term isolation -

  7. Heap leaching of clay ish uranium ores

    Gonzalez, E.; Sedano, A.

    1973-01-01

    This paper describes an experimental facility, built near El Lobo mine. In it we study the beneficiation of low-grade uranium ore. The mineral has a great amount of clay and fines. The flow-sheet used has four steps: head leaching, ph-ajustement, ion-exchange and participation. We show, also, the most interesting results. (Author)

  8. Calm, Cool, and Comfortable in Clay

    Stylianou, Xanthippi Cynthia

    2010-01-01

    The author's fourth-grade students had just finished a drawing unit that focused on the human figure. Projects included charcoal gesture drawings and chalk manikin drawings in chiaroscuro. She wanted to integrate a new medium for students to continue their study of the human figure. Since students are always excited to work with clay, making clay…

  9. Classroom Instruction: The Influences of Marie Clay

    McNaughton, Stuart

    2014-01-01

    Marie Clay's body of work has influenced classroom instruction in direct and indirect ways, through large overarching themes in our pedagogical content knowledge as well as specific smart practices. This paper focuses on her the contributions to our thinking about instruction which come from two broad theoretical concepts; emergent literacy…

  10. Diffusion in Clay Layers and Groundwater Remediation

    In a collaborative SERDP-funded study, researchers from the Air Force Institute of Technology, the U.S. Environmental Protection Agency, and the University of Michigan developed a numerical model that simulates the enhanced transport of CAHs into and out of low permeability clay ...

  11. Clay Shirky, Internet e il collegio invisibile

    Maria Chiara Pievatolo

    2011-10-01

    Full Text Available Come Internet sta cambiando il nostro modo di pensare? Fra le 172 risposte presentate da Edge, Clay Shirky ne propone una particolarmente interessante per i ricercatori di professione. Internet, scrive Shirky, ha aumentato straordinariamente la capacità espressiva dell’umanità. Ma che una risorsa divenga abbondante, da scarsa che era, è una sfortuna, almeno per chi su [...

  12. Mineralogical and Geochemical Characterization of Clay and ...

    Bheema

    which include soil horizons, continental and marine sediments, geothermal fields, volcanic ... water, air, or steam and the type of clay however is controlled by the composition of pre-existing ... the lake basin is characterized by biannual nature of precipitation with a mean annual ...... isotope record from LakeAshenge.

  13. Clay Corner: Recreating Chinese Bronze Vessels.

    Gamble, Harriet

    1998-01-01

    Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

  14. Transport of Organic Solutes in Clay Formations

    The research is a pilot investigation for the SERDP (Strategic Environmental Research and Development Program, DoD) founded project, Impact of Clay-DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones, from 2010-2012. The report tries to s...

  15. Thermal stability of PMMA–clay hybrids

    Administrator

    Thermal stability of PMMA–clay hybrids. TANUSHREE CHOUDHURY* and NIRENDRA M MISRA. Department of Applied Chemistry, Indian School of Mines University, Dhanbad 826 004, India. MS received 9 December 2008. Abstract. Materials with small particle size are being extensively used in composites and hybrid ...

  16. Laboratory study of the Flandres clay swelling

    Khaddaj, Said

    1992-01-01

    The first chapter contains a survey about the swelling of soils, and about the experimental methods used to characterize this phenomenon. A classification of soils in function of their swelling potential is proposed. The second chapter deals with the properties of Flandres clay. Chemical and mineralogical compositions, mechanical properties and free swell index are given. The third chapter contains a presentation of the study of the swelling potential of Flandres clay using the oedometer. Four methods are described and used (free-swell, different pressures, pre-swell and direct-swell). A numerical simulation of free-swell tests is also given. The fourth chapter includes a presentation of the study of the swelling behaviour of Flandres clay using a triaxial cell. Three methods are used: free-swell, pre-swell and different-pressures. The last chapter contains a parametric study of the swelling behaviour of Flandres clay. The influence of some parameters such as sample thickness, initial water content, vertical load and load history is presented. (author) [fr

  17. Geotechnical studies of Jaitapur marine clay

    Bhat, S.T.; Nayak, B.U.

    characterisEd. by high water content and high Atterberg limits. Undrained shear strength varied from 1.8 to 6 KPa. These were moderately sensitive clays. Carbonate content which varied from 3 to 27%, was found to influence engineering properties of the soil...

  18. Production of smectite organophylic clays from three commercial sodium bentonite

    Valenzuela Diaz, Francisco R.; Souza Santos, Persio de

    1995-01-01

    Laboratory cationic exchange procedures using Brazilian's commercial quaternary ammonium salt and three samples of commercial sodium bentonites (two Brazilian's and one from Wyoming (US) are described. Swelling values in some liquid organic media are shown for the organophilic clays and for a Brazilian's commercial organophilic clay. Organophilic clays with larger swelling values than the commercial organophilic clay in kerosene, Varsol, toluene and soya bean oil were obtained. (author)

  19. Repository tunnel construction in deep clay formations

    Clarke, B.G.; Mair, R.J.; Taylor, R.N.

    1992-01-01

    One of the objects of the Hades project at Mol, Belgium has been to evaluate the feasibility of construction of a deep repository in the Boom clay formation at depth of approximately 225 metres. The main objective of the present project was to analyse and interpret the detailed geotechnical measurements made around the Hades trial shaft and tunnel excavations and evaluate the safety of radioactive waste disposal in a repository facility in deep clay formations. Plasticity calculations and finite element analyses were used which gave results consistent with the in-situ measurements. It was shown that effective stress analysis could successfully predict the observed field behaviour. Correct modelling of the small-strain stiffness of the Boom clay was essential if reasonable predictions of the pore pressure response due to construction are to be made. The calculations undertaken indicated that, even in the long term, the pressures on the test drift tunnel lining are likely to be significantly lower than the overburden pressure. Larger long-term tunnel lining pressures are predicted for impermeable linings. A series of laboratory stress path tests was undertaken to determine the strength and stiffness characteristics of the Boom clay. The tests were conducted at appropriate effective stress levels on high-quality samples retrieved during construction of the test drift. The apparatus developed for the testing is described and the results discussed. The development of a self boring retracting pressure-meter is described. This novel in-situ testing device was specifically designed to determine from direct measurements the convergence/confinement curve relevant to tunnelling in clay formations. 44 refs., 60 figs., 3 tabs

  20. Faults in clays their detection and properties

    Baldi, G.; Carabelli, E.; Chiantore, V.; Colombo, P.F.; Gruszka, A.; Pensieri, R.; Superbo, S.; Gera, F.

    1991-01-01

    The 'Faults in clays project', a cooperative research effort between Ismes and Enea of Italy and BGS and Exeter University of the UK, has been aimed at assessing and improving the resolution capability of some high resolution geophysical techniques for the detection of discontinuities in clay formations. All Ismes activities have been carried out in Italy: they consisted in the search of one or more sites - faulted clay formations - suitable for the execution of geophysical and geotechnical investigations, in the execution of such tests and in additional geological surveys and laboratory (geotechnical and geochemical) testing. The selected sites were two quarries in plio-pleistocenic clay formations in central Italy where faults had been observed. The greatest part of the research work has been carried out in the Orte site where also two 90 m boreholes have been drilled and cored. Geophysical work at Orte consisted of vertical electrical soundings (VESs) and horizontal electrical lines (HELs), four high resolution seismic reflection lines, and in-hole and cross-hole logs. Laboratory activities were geotechnical characterization and permeability tests, and measurements of disequilibrium in the uranium decay series. At Narni, where Exeter University sampled soil gases for geochemical analyses, the geophysical work consisted in a geo-electrical survey (five VESs and two HELs), and in two high resolution reflection seismic lines. Additional investigations included a structural geology survey. The main conclusion of the research is that current geophysical techniques do not have a resolution capacity sufficient to detect the existence and determine the characteristics of faults in deep homogeneous clay formations

  1. Water-clay interactions. Experimental study

    Gaucher, Eric

    1998-01-01

    Clay minerals contribute to the chemical composition of soil and sediment groundwaters via surface and dissolution/precipitation reactions. The understanding of those processes is still today fragmentary. In this context, our experimental purpose is to identify the contribution of each reaction in the chemical composition of water in a water/clay System. Kaolinite, illite, montmorillonite are the reference clays. After a fine mineralogical study, the exchange equilibria between K + and H + are characterised. Different exchange sites are identified and the exchange capacities and selectivity coefficients are quantified. Then, mixtures of the three clays are equilibrated with acidic and basic (I≤10 -2 M) solutions at 25 deg. C, 60 deg. C, 80 deg. C, during 320 days. The System evolution is observed by chemical analysis of the solutions and mineralogical analysis by TEM. We show that montmorillonite is unstable compared to the kaolinite/amorphous silica assemblage for solutions of pH<7. Aqueous silica is probably controlled by the kinetics of dissolution of the montmorillonite in moderate pH media. In more acidic solutions, amorphous silica precipitates. Al is under control of 'kaolinite' neo-formations. The use of the selectivity coefficients in a numerical simulation shows that K + concentration depends on exchange reactions. The pH has a more complicated evolution, which is not completely understood. This evolution depends on both exchange equilibria and organic acid occurrence. In this type of experiments, we have demonstrated that the equilibrium equations between smectite and kaolinite are inexact. The problem of the thermodynamic nature of clays remains and is not resolved by these solubility experiments. (author) [fr

  2. Migration of leachate solution through clay soil

    Abdel Warith, M M

    1987-01-01

    The problem of domestic solid wastes buried in landfill sites is viewed from the aspect of leachate contamination and migration in the substrate, and the efficiency of natural clay barriers as an expedient economic lining material is assessed. Various chemical constituents of the landfill leachate of an actual waste containment site at Lachenaie (35 km east of Montreal) were determined from samples collected from specially designed basins. Data for companion tests on laboratory columns are also presented. Chemical analysis on samples from the basins and leachates from the columns measured changes in the concentration of: (a) cations (Na, K, Ca, and Mg), (b) anions (Cl, HCO/sub 3/, and CO/sub 3/) (c) total organic carbon (TOC), and (d) heavy metals (Fe, Zn, Pb, and Cu). The physical parameters measured included: (a) pH, and (b) specific conductivity. Predictions, using a dispersion-convection model for concentration profile development for either adsorbed or retained contaminants, were compared with the experimentally determined profiles (both in leaching columns and landfill laboratory model). Another set of experiments was also conducted to evaluate the effect of some organic fluids on the geotechnical properties of different clay soils (natural clay and two reference clay soils: illite and kaolinite). The results from this study have demonstrated that the natural clay soil can be used to adequately contain the different contaminant species usually present in the leachate solutions. Furthermore, the data suggested that under favorable soil conditions, landfill leachates containing low levels of trace metals will not pose a substantial contamination threat to the subsurface environment, provided that a proper thickness of barrier is used.

  3. Change effects in the land use about the mineral clay

    Cespedes Payret, C.; Gutierrez, O; Panario, D.; Pineiro, G

    2012-01-01

    The Pampas land changes during the Quaternary, left their mark on the mineralogy of soil clays. This work is oriented to compare the mineralogical composition of the clays and the value of potassium in an eucalyptus forestation. These results show that the mineralogical illite alteration is the cause of its destruction. This clay is the main reservoir of potassium for the agricultural soils

  4. Geological Investigations on Boulder-Clay of E. Groningen

    Gijzel, van P.; Overweel, C.J.; Veenstra, H.J.

    1959-01-01

    In this article the results of a study on boulder-clay in the neighbourhood of Winschoten (N.E. Netherlands) are communicated (Chapter I). The underlying sediments of the boulder-clay in this area consist of fine preglacial sands and black clay. In the nuclei of the many drumlins a strongly

  5. Traditional mining and mineralogy of geophagic clays from Limpopo ...

    Geophagic clays consumed were whitish, yellowish, khaki and black; mined from hills and mountains, river beds, valleys, excavation sites and termitaria. Geophagic individuals from Free State preferred whitish geophagic clays; and sometimes khaki. Yellowish clays were preferred mostly by geophagic individuals from ...

  6. Polymer-clay nanocomposites obtained by solution polymerization ...

    Clay minerals can be found all over the world.1 Clay minerals have ... salts or covalent bonding with silanes at the OH edges of the clay. ..... Marras S I, Tsimpliaraki A, Zuburtikudis I and ... Mansoori Y, Roojaei K, Zamanloo M R and Imanzadeh.

  7. Use of clay from kangerlussuaq in the Greenlandic construction industry

    Belmonte, Louise Josefine; Villumsen, Arne; Ottosen, Lisbeth M.

    2010-01-01

    Clay material from Kangerlussuaq in West Greenland was characterised and its possible use for the production of bricks, expanded clay products and inert filler material was investigated. It was generally found that it was possible to use the clay in all of the above mentioned materials, although,...

  8. Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take...

  9. Characterization of groundwater dynamics in landslides in varved clays

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  10. Characterization of groundwater dynamics in landslides in varved clays

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trieves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  11. Enrichment and activation of smectite-poor clay

    Sarcevica, Inese; Kostjukovs, Juris; Actint, Andris, E-mail: inese.sarcevicha@gmail.com [Department of Chemistry, University of Latvia, Kr. Valdemara street 48, Riga (Latvia)

    2011-06-23

    A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

  12. Experimental study of mechanical behaviour of a clay-stone: application to nuclear waste disposals

    Chiarelli, A.S.; Shao, J.F.; Ledesert, B.; Hoteit, N.

    2001-01-01

    A study of mechanical behaviour of deep argillaceous rocks from East of France, the 'argilites de l'Est' as a potential host rock for radioactive waste disposal studied by ANDRA, (french national radioactive waste management agency) is presented. Some uniaxial and triaxial compression tests with unloading-reloading cycles were realised on samples from three different depths. Important plastic strains associated to directional degradation of elastic properties show that the two principles strain mechanisms are plasticity and induced anisotropic damage. At microscopic scale, it is related to sliding of clay sheets and oriented microcracks. The influence of mineralogy is that brittle behaviour is more important with calcite while it decreases with clay. (authors)

  13. Performance assessment of the disposal of vitrified high-level waste in a clay layer

    Mallants, Dirk; Marivoet, Jan; Sillen, Xavier

    2001-01-01

    Deep disposal is considered a safe solution to the management of high-level radioactive waste. The safety is usually demonstrated by means of a performance assessment. This paper discusses the methodological aspects and some of the results obtained for the performance assessment of the disposal of vitrified high-level waste in a clay layer in Belgium. The calculations consider radionuclide migration through the following multi-barrier components, all of which contribute to the overall safety: (1) engineered barriers and the host clay layer, (2) overlying aquifer, and (3) biosphere. The interfaces between aquifers and biosphere are limited to the well and river pathway. Results of the performance assessment calculations are given in terms of the time evolution of the dose rates of the most important fission and activation products and actinides. The role of the glass matrix in the overall performance of the repository is also discussed

  14. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite

    Aublive-Conil, N.

    2003-03-01

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  15. Evaluation of kaolinite clays of Moa for the production of cement based clinker-calcined clay-limestone (LC3

    Roger S. Almenares-Reyes

    2016-12-01

    Full Text Available Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (ATG. These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1, although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C.

  16. Boom clay pore water, home of a diverse microbial community

    Wouters, Katinka; Moors, Hugo; Leys, Natalie

    2012-01-01

    Document available in extended abstract form only. Boom Clay pore water (BCPW) has been studied in the framework of geological disposal of nuclear waste for over two decades, thereby mainly addressing its geochemical properties. A reference composition for synthetic clay water has been derived earlier by modelling and spatial calibration efforts, mainly based on interstitial water sampled from different layers within the Boom clay. However, since microbial activity is found in a range of extreme circumstances, the possibility of microbes interacting with future radioactive waste in a host formation like Boom Clay, cannot be ignored. In this respect, BCPW was sampled from different Boom Clay layers using the Morpheus piezometer and subsequently analysed by a complementary set of microbiological and molecular techniques, in search for overall shared and abundant microorganisms. Similar to the previous characterization of the 'average' BCPW chemical composition, the primary aim of this microbiological study is to determine a representative BCPW microbial community which can be used in laboratory studies. Secondly, the in situ activity and the metabolic properties of members of this community were addressed, aiming to assess their survival and proliferation chances in repository conditions. In a first approach, total microbial DNA of the community was extracted from the BCPW samples. This molecular approach allows a broad insight in the total microbial ecology of the BCPW samples. By polymerase chain reaction (PCR) on the highly conserved 16S rRNA genes in this DNA pool and subsequent sequencing and bio-informatics analysis, operational taxonomic units (OTUs) could be assigned to the microbial community. The bacterial community was found to be quite diverse, with OTUs belonging to 8 different phyla (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chlorobi, Spirochetes, Chloroflexi and Deinococcus-Thermus). These results provide an overall view of the

  17. Boom clay pore water, home of a diverse microbial community

    Wouters, Katinka; Moors, Hugo; Leys, Natalie [SCK.CEN, Environment, Health and Safety Institute, B-2400 Mol (Belgium)

    2012-10-15

    Document available in extended abstract form only. Boom Clay pore water (BCPW) has been studied in the framework of geological disposal of nuclear waste for over two decades, thereby mainly addressing its geochemical properties. A reference composition for synthetic clay water has been derived earlier by modelling and spatial calibration efforts, mainly based on interstitial water sampled from different layers within the Boom clay. However, since microbial activity is found in a range of extreme circumstances, the possibility of microbes interacting with future radioactive waste in a host formation like Boom Clay, cannot be ignored. In this respect, BCPW was sampled from different Boom Clay layers using the Morpheus piezometer and subsequently analysed by a complementary set of microbiological and molecular techniques, in search for overall shared and abundant microorganisms. Similar to the previous characterization of the 'average' BCPW chemical composition, the primary aim of this microbiological study is to determine a representative BCPW microbial community which can be used in laboratory studies. Secondly, the in situ activity and the metabolic properties of members of this community were addressed, aiming to assess their survival and proliferation chances in repository conditions. In a first approach, total microbial DNA of the community was extracted from the BCPW samples. This molecular approach allows a broad insight in the total microbial ecology of the BCPW samples. By polymerase chain reaction (PCR) on the highly conserved 16S rRNA genes in this DNA pool and subsequent sequencing and bio-informatics analysis, operational taxonomic units (OTUs) could be assigned to the microbial community. The bacterial community was found to be quite diverse, with OTUs belonging to 8 different phyla (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chlorobi, Spirochetes, Chloroflexi and Deinococcus-Thermus). These results provide an overall view of the

  18. Clays causing adhesion with tool surfaces during mechanical tunnel driving

    Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

    2009-04-01

    During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

  19. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Landrou Gnanli

    2017-01-01

    Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  20. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

    2017-06-01

    In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  1. Pure and impure clays and their firing products

    Murad, E.; Wagner, U.

    1989-01-01

    Moessbauer spectroscopy is highly suited for the study of clays whose industrial uses depend on the iron content. Reactions that take place during clay firing can be readily monitored by Moessbauer spectroscopy. Following dehydroxylation of clay minerals, the quadrupole splitting of octahedrally coordinated iron (III) increases abruptly, but reverts to lower values upon the formation of new, better ordered phases at higher temperatures. It is also shown that iron oxides may account for a considerably higher proportion of the total iron content of many clays than is commonly recognized, and their existence must be taken into consideration for a correct interpretation of the Moessbauer spectra of clays. (orig.)

  2. Performance Study of the Natural Rubber Composite with Clay Minerals

    Nyo Nyo Myint; Tin Tin Aye; Kyaw Myo Naing; Nyunt Wynn

    2008-03-01

    The preparation, characterization and some applications of natural rubber clay composite have been studied. This study investigated the possibility of natural rubber latex to replace some part of natural clays. In formulation of rubber clay composite from natural rubber latex and various clay minerals, three main steps were involved (i) preparation of latex cream (ii) prevulcanization of latex cream (iii) mixing vulcanized latex compound, with other ingredients. In each step, several parameters have been carefully investigated to optimize the performance of natural rubber clay composite production. The composite products were of better quality and can be considered to be more cost effective.

  3. Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

    El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

    2017-04-01

    Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite

  4. Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

    Moran, Anthony R.; Hettiarachchi, Hiroshan

    2011-01-01

    Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

  5. Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

    Anthony R. Moran

    2011-06-01

    Full Text Available Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

  6. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Mercante, Luiza A. [Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação, São Carlos, SP 13560 970 (Brazil); Soriano, Stéphane [Instituto de Física, Universidade Federal Fluminense, Niterói, RJ 24.210 346 (Brazil); Andruh, Marius [Inorganic Chemistry Laboratory, Faculty of Chemistry, University of Bucharest, Str. Dumbrava Rosie nr. 23, Bucharest (Romania); Vieira, Méri D., E-mail: gqimeri@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Vaz, Maria G.F., E-mail: mariavaz@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil)

    2015-08-15

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.

  7. Clay mineral type effect on bacterial enteropathogen survival in soil.

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. © 2013.

  8. Sorption of Pu onto some kinds of clay

    Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

    2010-01-01

    There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

  9. Feasibility of classification of clay minerals by using PAS

    Honda, Y; Yoshida, Y; Akiyama, Y; Nishijima, S

    2015-01-01

    After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found. (paper)

  10. Rheological characterization of nanocomposites Nylon 6/bentonite clay

    Silva, T.R.G.; Fernandes, P.C.; Oliveira, S.V.; Araujo, E.M.; Melo, T.J.A.

    2010-01-01

    Polymer nanocomposites are a class of materials that have been widely used in various applications. Among them, has been emphasizing the preparation of polymer films with barrier properties for applications in polymer membranes. In this work, nanocomposites of nylon 6/bentonite clay were obtained from a Homogenizer, in the ratios of 1, 3 and 5 wt% clay. The Brasgel PA bentonite clay was treated organically with Praepagen HY salt, to make it organophilic. By X-ray diffraction (XRD), it was showed that the efficiency of the incorporation of salt in the clay. The rheological curves showed that for the AST clay the torque did not change when compared with the pure nylon 6, while for the clay ACT, the torque increased gradually with the percentage of clay. (author)

  11. Organically modified clay removes oil from water

    Alther, G.R.

    1995-01-01

    When bentonite or other clays and zeolites are modified with quaternary amines, they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease, and other sparingly soluble organics. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOG's and chlorinated hydrocarbons. In this application the clay is mixed with anthrazite to prevent early plugging of the filter by oil or grease droplets. In batch systems a powered organoclay is employed. Types of oil found in water can include fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, diesel oils; and light hydrocarbons such as kerosene, jet fuel, and gasoline

  12. Clay-based geothermal drilling fluids

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  13. Organoclays obtaining starting up of clays sodium

    Silva, M.M. da; Mota, M.F.; Oliveira, G.C. de; Rodrigues, M.G.F.

    2012-01-01

    Clays have several applications in many areas of fields of technology, however, modification of these materials using organic compounds can be performed to obtain further hydrophobic materials, for applications in the adsorption of organic pollutants. This study aimed to analyze the effects of modifying two clays using sodium quaternary ammonium surfactants through ion exchange reaction process, in obtaining organoclays. The samples with sodium and organoclays were characterized by the techniques of X-ray diffraction (XRD), Infrared Spectroscopy in the region (IV), Gravimetric and Differential Thermal Analysis (DTA / TG) and organic adsorption tests. The results show that the process of obtaining organoclay is efficient, and materials have the potential for future applications in removing organic contaminants. (author)

  14. Rheological properties of sodium smectite clay

    Boergesson, L.; Hoekmark, H.; Karnland, O.

    1988-12-01

    The rheological properties of Na-smectite Mx-80 have been investigated by various laboratory tests. The investigations include determination of the hydraulic conductivity, the undrained stress-strain-strength properties, the creep properties, the compression and swelling properties in drained and undrained conditions and the undrained thermomechanical properties. Measurements have been made at different densities, clay/sand mixtures and pore water compositions. The influence of temperature, rate of strain and testing technique has also been considered. The investigation has led to a supply of basic data for the material models which will be used at performance calculations. The results have also increased the general understanding of the function of smectitic clay as buffer material. The microstructural behaviour has been considered at the validation of the different test results and the validity of the effective stress theory has been discussed. Comparisons with the properties of Ca-smectite have also been made. (orig.)

  15. Moessbauer spectroscopy of iron in clay minerals

    Raclavsky, K.; Sitek, J.; Lipka, J.

    1975-01-01

    Selected pure clay minerals predominantly of Czechoslovak origin were studied, such as montmorillonite, nontronite, beidellite, glauconite, seladonite, illite, vermiculite, saponite, palygorskite, goethite. Moessbauer measurements were performed at room temperature with a 57 Co in Pd source. The spectra were fitted by the least square method. The parameters of the measured Moessbauer spectra are given. The values of isomer shifts, quadrupole splittings and line widths were obtained with an error of +- 0.03 mm/sec. (Z.S.)

  16. Octyl Phenol Synthesis Using Natural Clays

    S. Casuscelli

    2000-03-01

    Full Text Available A series of clay minerals, HB, NB and Al-PILC have been studied in the alkylation reactions of 2-octanol with phenol at 180°C, under conditions of alcohol/phenol = 1 (mole ratio and W/FAo °= 64,27 ghmol-1. The selectivity of Al-PILC was 77,12% for octyl phenol and 16,5% for dioctyl phenol.

  17. Determining redox properties of clay-rich sedimentary deposits in the context of performance assessment of radioactive waste repositories : Conceptual and practical aspects

    Behrends, T.; Bruggeman, Christophe

    Redox reactions play a key factor controlling the mobility of redox sensitive radionuclides in clay-rich sediments which might serve as host formations for radioactive waste repositories. Assessing the redox speciation of radionuclides requires information about the redox conditions in the formation

  18. Spectromicroscopy of Fe distributions in clay microcrystals

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  19. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  20. Influence of clay organic modifier on morphology and performance of poly(ε-caprolactone/clay nanocomposites

    Nikolić Marija S.

    2015-01-01

    Full Text Available Two series of poly(e-caprolactone nanocomposites with different organo-modified clays (1 to 8 wt% were prepared by the solution casting method. Organoclays with polar (Cloisite®C30B and nonpolar (Cloisite®C15A organic modifier and with different miscibility with poly(e-caprolactone matrix, were chosen. Exfoliated and/or intercalated nanocomposite’s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite®C30B, which had better miscibility with poly(e-caprolactone matrix. Differences in spherulites’ sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young’s modulus with experimentally obtained ones in tensile tests.[Projekat Ministarstva nauke Republike Srbije, br. 172062

  1. Atrazine biodegradation modulated by clays and clay/humic acid complexes

    Besse-Hoggan, Pascale; Alekseeva, Tatiana; Sancelme, Martine; Delort, Anne-Marie; Forano, Claude

    2009-01-01

    The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

  2. Evaluation of the bleaching flux in clays containing hematite and different clay minerals

    Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos; Morelli, M.R.

    2016-01-01

    Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

  3. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

    2009-07-01

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  4. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

    2009-01-01

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  5. The elastoplastic response of and moisture diffusion through a vinyl ester resin-clay nanocomposite

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2002-01-01

    Experimental data are reported on the elastoplastic response of and moisture diffusion through a vinyl ester resin–montmorillonite clay nanocomposite with various amounts of filler. Two simple models are developed for the elastoplastic behavior of a nanocomposite and for the anomalous diffusion...... of penetrant molecules. Adjustable parameters in the constitutive equations are found by fitting the observations. It is revealed that some critical concentration of filler exists (about 1 wt.-%): in the sub-critical region of concentrations, molecular mobility of the host polymer strongly decreases...

  6. Microbial processes relevant for the long-term performance of radioactive waste repositories in clays

    Meleshyn, Artur

    2012-01-01

    Document available in extended abstract form only. A number of investigations on occurrence and viability of microbes in compacted clays have been aimed at studying possible microbial effects on long-term performance of a deep geological repository (DGR) for high-level radioactive waste (HLW) and spent nuclear fuel (SF). Compacted clays are considered in current DGR designs either as a buffer material or as a host rock. The primary purpose of the present work was to qualitatively evaluate the relevance of microbial activity for the long-term performance of a DGR and to identify which safety-relevant processes and properties can be potentially influenced by this activity. The present analysis identified eight clay properties essential for maintaining safety functions of containment and retardation of the disposal system - swelling pressure, specific surface area, cation exchange capacity, anion sorption capacity, porosity, permeability, fluid pressure, plasticity - which can potentially be influenced by microbial processes in clay buffer and Clay-stone within a DGR for HLW/SF. Iron(III)- and sulphate-reducing, fermentative, methane-producing and oxidizing microbes can be considered to be present in any clay formation. Each habitat includes a massive number of microbial niches with perhaps only a small proportion of the species being metabolically active at the habitat's conditions, the remainder becoming not extinct. Moreover, clays contain electron donors and electron acceptors in amounts sufficient for these microbes to remain active during very long periods of time. Additional sources of electron donors or electron acceptors will inevitably be added to the repository system as a result of DGR excavation, placement of radioactive waste as well as backfilling and sealing of the DGR. In no case should the potential impact of microbes be underestimated based on a possible argument of comparably low biomass of the microbes in contact with metal surfaces or dissolved

  7. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

  8. Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

    Ruplis, A.; Mezinskis, G.; Chaghuri, M.

    1998-01-01

    Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

  9. Comparing uranyl sorption complexes on soil and reference clays

    Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

    1993-01-01

    Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

  10. A new coupled elastoplastic damage model for clay-stone and its parameter identification

    Jia, S.P.; Chen, W.Z.; Yu, H.D.; Li, X.L.; Sillen, X.

    2010-01-01

    Document available in extended abstract form only. In Belgium, the Boom Clay is considered as a potential host rock for the geological disposal of the high level nuclear waste and is intensively studied from hydro-mechanical point of view. Laboratory tests on Boom clay shown that the Boom clay presents very complex stress strain behaviour. Undrained triaxial tests indicated often a hardening behaviour at small deformation and softening at larger deformation. It is not easy to give an explicit function to describe the stress-strain behaviour under triaxial stress state. The mechanical characteristics are obviously affected by the porosity, fractures growth, water content, and stress, etc., four stages can be usually distinguished from the stress-strain curve of Boom Clay, named as OA, AB, BC and CD. 1) Stage OA, the relation between stress and strain is linear. This stage is elastic state, and point A is called as yield strength σ c0 . 2) Stage AB, the weak fractures in the rock appear, develop and cumulate gradually. Point B is called peak strength σ cu . 3) Stage BC, peak strength is reached and stress reduces with the increasing of strain, up to the residual strength. This stage is called strain softening and point C is the residual strength σ cr . The axial pressure causes the fracture developing and strength reducing. 4) Stage CD, the final strength doesn't reduce obviously with the development of plastic deformation. This stage is called plastic flow. Obviously, The conventional elasto-plastic constitutive model can not describe the mechanical behaviours of Boom Clay. Based on damage mechanics theory, an new elasto-plastic damage constitutive model is put forward and applied to Boom Clay, which can describe the complex stress-strain behaviour of clay. It is described as follows: stage OA with an elastic model, stage AB with elastic damage model, stage BC and stage CD with plastic damage model. The complete process curve of stress-strain can be divided

  11. The HADES demonstration and pilot project on radioactive waste disposal in a clay formation

    Bonne, A.; Beckers, H.; Beaufays, R.; Buyens, M.; Coursier, J.; Bruyn, D. de; Fonteyne, A.; Genicot, J.; Lamy, D.; Meynendonckx, P.; Monsecour, M.; Neerdael, B.; Noynaert, L.; Voet, M.; Volekaert, G.

    1992-01-01

    The overall objective of the HADES programme is the evaluation of the technical feasibility and safety of the disposal of radwaste in a deep clay formation. The pilot phase is aimed at demonstrating the system behaviour for those components of the system and those operations and issues which can be demonstrated directly. The time period considered covers a first phase of the development programme of the pilot project which includes: -The construction of a concrete lined tests drift of about 30 m length with a useful inner diameter of 3.5 m. In the lining, a number of openings or ports are foreseen for emplacing the various tests and sensors for the general auscultation in the host rock; - Mine-by test for the investigation of the response of the surrounding clay on the excavating; - CERBERUS test, a combined heating-irradiation test aiming at evaluating by simulation (electrical heaters and Co-60 radiation source) the impact of a HLW canister on its immediate near field; - Design of a gallery heating test for the demonstration by simulation of the behaviour of a concrete lined gallery structure and of the surrounding clay mass in a temperature field (TEMPPRES code for temperature and pressure evolution simulation). 21 refs

  12. Ultra-thin clay layers facilitate seismic slip in carbonate faults.

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

    2017-04-06

    Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

  13. Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

    Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

    2010-01-01

    Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were

  14. Studies on Tagged Clay Migration Due to Water Movement

    Scharpenseel, H. W. [Institut fuer Bodenkunde der Universitaet Bonn, Federal Republic of Germany (Germany); Kerpen, W. [Arbeitsgruppe, Institut fuer Landwirtschaft der KFA Juelich, Bonn, Federal Republic of Germany (Germany)

    1967-11-15

    {sup 55}Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B{sub t}-development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of {sup 55}Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for {sup 55}Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

  15. Studies on Tagged Clay Migration Due to Water Movement

    Scharpenseel, H.W.; Kerpen, W.

    1967-01-01

    55 Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B t -development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of 55 Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for 55 Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

  16. Clay facial masks: physicochemical stability at different storage temperatures.

    Zague, Vivian; de Almeida Silva, Diego; Baby, André Rolim; Kaneko, Telma Mary; Velasco, Maria Valéria Robles

    2007-01-01

    Clay facial masks--formulations that contain a high percentage of solids dispersed in a liquid vehicle--have become of special interest due to specific properties presented by clays, such as particle size, cooling index, high adsorption capacity, and plasticity. Although most of the physicochemical properties of clay dispersions have been studied, specific aspects concerning the physicochemical stability of clay mask products remain unclear. This work aimed at investigating the accelerated physicochemical stability of clay mask formulations stored at different temperatures. Formulations were subjected to centrifuge testing and to thermal treatment for 15 days, during which temperature was varied from -5.0 degrees to 45.0 degrees C. The apparent viscosity and visual aspect (homogeneity) of all formulations were affected by temperature variation, whereas color, odor, and pH value remained unaltered. These results, besides the estimation of physicochemical stability under aging, can be useful in determining the best storage conditions for clay-based formulations.

  17. Tensile mechanical response of polyethylene – clay nanocomposites.

    2007-03-01

    Full Text Available In this work we report on the microstructural and the mechanical characteristics of high density polyethylene (HDPE-clay nanocomposites, with particular attention to the creep behaviour. The samples were prepared through melt compounding, using two high-density polyethylenes with different melt flow rate (MFR, two different organo-modified clays, and changing the relative amount of a polyethylene grafted with maleic anhydride (PEgMA compatibilizer. The intercalation process is more effective as the matrix melt viscosity decreases (higher MFR, while the clay interlamellar spacing increases as the compatibilizer amount increases. The relative stiffness of the nanocomposites increases with the addition of clay, with a limited enhancement of the relative yield stress. The better intercalation obtained by the addition of the compatibilizer is not accompanied by a concurrent improvement of the tensile mechanical properties. The creep resistance is enhanced by the introduction of clay, with an appreciable dependence on both the polyethylene and the clay type.

  18. Characterization of organophilic attapulgite clay from state of Piaui

    Silva, L.C. dos Santos; Alves, T.S.; Barbosa, R.

    2011-01-01

    The attapulgite is mineral clay typically fibrous. It owns a superficial area around 125 to 210 m²/g, cationics transfer capacity from 20 to 30 mill equivalents per 100g of clay, high capacity of sorption, considerable decolourizer capacity, chemical inertia and maintenance of thixotropics properties in the presence of electrolytes. The objective of this work was to perform the chemical modification of attapulgite original from state of Piaui - Brazil, for applications in polymeric nanocomposites. The chemical composition of clay without modification was determined by X-Ray Diffraction. The natural clay and organophilizated one were characterized by X-Ray Diffraction (XRD), by Fourier Transform Infra-Red spectroscopy (FTIR), and Foster's swelling. The obtained results indicated the presence of characteristics groups of the salt in the clay, alteration in its chemical composition, evidencing that the chemical modification in the clay was efficient, could the same be applied in preparation of polymeric nanocomposites. (author)

  19. Nearfield behaviour of clay barriers and their interaction with concrete Task 3 characterization of radioactive waste forms a series of final reports (1985-89) No 26

    Atabek, R.; Beziat, A.; Coulon, H.; Dardaine, M.; Eglem, A.; Farcy, C.; Fontan, N.; Gatabin, C.; Gegout, P.; Lajudie, A.; Landoas, O.; Lechelle, J.; Plas, F.; Raynal, J.; Revertegat, E.; Debrabant, P.; Proust, D.

    1991-01-01

    In order to guarantee the safety of waste underground disposal, engineered barriers will be implemented as backfill materials in galleries and access shafts and as buffer materials between the host medium and the waste packages. One of the first requirements for engineered barriers is to minimize water and chemical species transfer. The materials being considered are essentially swelling clays, in particular calcium smectite clays coming from french deposits and hydraulic binders, more specially a ternary cement (named C.L.C.). A vitrified waste disposal in granite is taken as the most constraining scenario as far as engineered barrier is concerned. The clay buffer material is placed between the packages and the host rock. The main properties which are determined are directly related to the engineered barrier requirements: thermal conductivity, hydraulic conductivity, swelling pressure and swelling capacity. Moreover results are obtained on temperature effect on clay microstructure and properties in both cases: without and with water intake. The concrete durability with regard to clay pore water attack is evaluated taking into account previous results obtained to ensure low-level radioactive waste disposal safety. 23 refs., 29 figs., 10 tabs

  20. Joint project. Retention of radionuclides relevant for final disposal in natural clay rock and saline systems. Subproject 2. Geochemical behavior and transport of radionuclides in saline systems in the presence of repository-relevant organics. Final report

    Schmeide, Katja; Fritsch, Katharina; Lippold, Holger

    2016-01-01

    The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide - organics - clay - aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol kg -1 ) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol kg -1 NaClO 4 ) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc retention at

  1. Joint project. Retention of radionuclides relevant for final disposal in natural clay rock and saline systems. Subproject 2. Geochemical behavior and transport of radionuclides in saline systems in the presence of repository-relevant organics. Final report

    Schmeide, Katja; Fritsch, Katharina; Lippold, Holger [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Ressource Ecology; and others

    2016-08-01

    The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide - organics - clay - aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol kg{sup -1}) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol kg{sup -1} NaClO{sub 4}) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc

  2. Catalytic Wastewater Treatment Using Pillared Clays

    Perathoner, Siglinda; Centi, Gabriele

    After introduction on the use of solid catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), this review discussed the use of pillared clay (PILC) materials in three applications: (i) wet air catalytic oxidation (WACO), (ii) wet hydrogen peroxide catalytic oxidation (WHPCO) on Cu-PILC and Fe-PILC, and (iii) behavior of Ti-PILC and Fe-PILC in the photocatalytic or photo-Fenton conversion of pollutants. Literature data are critically analyzed to evidence the main direction to further investigate, in particularly with reference to the possible practical application of these technologies to treat industrial, municipal, or agro-food production wastewater.

  3. Uranyl adsorption at clay mineral surfaces

    Roesch, N. [Technische Univ. Muenchen (Germany). Fachgebiet Theoretische Chemie

    2016-11-01

    This first systematic survey of actinide adsorption at complex clay mineral surfaces, which provided new insights at the atomic level, is currently being extended to neptunyl NpO{sub 2}{sup +} and more complex minerals, like iron-substituted phyllosilicates. In this way we examine if the concepts developed so far can be applied more generally to support the interpretation of pertinent experiments. A further facet of these studies is to account also for the dynamic nature of the mineral/water interface by means of exemplary dynamic simulations.

  4. Electrochemical remediation of copper contaminated clay soils

    Korolev, V.A.; Babakina, O.A.; Mitojan, R.A. [Moscow State Univ. (Russian Federation)

    2001-07-01

    The study objective focused on electrochemical remediation copper polluted soils in the presence of adjuvant substances and conditions that are more effective for the treatment. Some of these substances were studied in different researches. Moreover, authors obtained a result of extraction copper rate higher than 90%. In this connection the following problems were set: - Influence organic and inorganic substances on copper mobility in soil under the DC current. - Moisture effect on copper migration in clay. - Electrochemical remediation soils different mineralogical composition. - A washing conditions contribution to electrochemical remediation of soil from copper. - Accuracy rating experimental dates. (orig.)

  5. Clay Ceramic Filter for Water Treatment

    Zereffa Enyew Amare

    2017-05-01

    Full Text Available Ceramic water filters were prepared from different proportions of kaolin and soft wood and sintered at 900 °C, 950 °C, and 1000 °C. The flow rate, conductivity, pH of filtered water and removal efficiency (microbial, water hardness agent’s, nitrite and turbidity were analysed. The ceramic filter with 15 % saw dust, 80 % clay and 5 % grog that was fired at temperature of 950 °C or 1000 °C showed the best removal efficiency. Statistical ANOVA tests showed a significant difference between ceramic filters with various compositions in their removal efficiencies.

  6. Reagent for treating clay drilling muds

    Tkachenko, P V; Leshchinskiy, P A; Shnaper, B I; Zinchuk, I F; Zlobin, V P

    1982-01-01

    A reagent is proposed for treating clay drilling muds. It contains lignite, caustic soda and modifying agent. It is distinguished by the fact that in order to reduce the cost of the reagent with simultaneous decrease in the viscosity and static shear stress of the drilling mud, it additionally contains iron sulfate, and the modifying agent contained is wastes of carbonic acid production with the following ratio of components (parts by weight): lignite 10.0-15.0, caustic soda 2.0-3.0, wastes of carbonic acid production 0.5-0.75; iron sulfate 1.0-2.0.

  7. Analysis of cement-treated clay behavior by micromechanical approach

    Zhang , Dong-Mei; Yin , Zhenyu; Hicher , Pierre Yves; Huang , Hong-Wei

    2013-01-01

    International audience; Experimental results show the significant influence of cement content on the mechanical properties of cement-treated clays. Cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debo...

  8. Production of polyol carbonates and their intercalation into Smectite clays

    Shaheen, Uzma

    2017-01-01

    In hyper-saline conditions, clays in geosynthetic clay liners contract and fail to form a hydraulic barrier due to removal of water from the interlayer spaces of smectite, which is the swelling mineral component of bentonites used in geosynthetic clay liners. Five-membered cyclic carbonates such as propylene carbonate have been reported to form stable intercalated complexes with hydrated Na-smectite, which maintain swollen states at 1M). Glycerol carbonate was selected as an alternative c...

  9. GRS' research on clay rock in the Mont Terri underground laboratory

    Wieczorek, Klaus; Czaikowski, Oliver [Gesellschaft fuer Anlagen- und Reaktorsicherheit gGmbH, Braunschweig (Germany)

    2016-07-15

    For constructing a nuclear waste repository and for ensuring the safety requirements are met over very long time periods, thorough knowledge about the safety-relevant processes occurring in the coupled system of waste containers, engineered barriers, and the host rock is indispensable. For respectively targeted research work, the Mont Terri rock laboratory is a unique facility where repository research is performed in a clay rock environment. It is run by 16 international partners, and a great variety of questions are investigated. Some of the work which GRS as one of the Mont Terri partners is involved in is presented in this article. The focus is on thermal, hydraulic and mechanical behaviour of host rock and/or engineered barriers.

  10. Microstructures and physical properties of "backfill" clays: comparison of residua and sedimentary montmorillonite clays

    Přikryl, R.; Ryndová, T.; Boháč, J.; Weishauptová, Zuzana

    2003-01-01

    Roč. 23, 1-4 (2003), s. 149-156 ISSN 0169-1317 R&D Projects: GA AV ČR IAA2046101 Institutional research plan: CEZ:AV0Z3046908 Keywords : bentonite * montmorillonite-rich clay * hydrophysical properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.287, year: 2003

  11. Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

    Simona eLongo

    2013-11-01

    Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

  12. Diffusion, sorption and stability of radionuclide-organic complexes in clays and clay-organic complexes

    Staunton, S.; Rees, L.V.C.

    1991-01-01

    The dependence on various parameters of the diffusion coefficient of neptunium (V) in clay systems has been studied. The effect of the clay mineralogy, the charge compensating cation in the clay, the ionic strength of a background perchlorate solution and the presence of three organic ligands have been investigated. The diffusion coefficients were compared to those predicted if diffusion occurred only in the liquid phase and adsorption was reversible; agreement was fairly good. An approximation to the diffusion coefficient can thus be obtained from readily measured experimental parameters. There is no evidence of surface phase diffusion. The most significant factor in determining the diffusion coefficient is the magnitude of the distribution ratio, itself highly dependent on the nature of the clay. Neither EDTA nor citrate modified the diffusion coefficient. Although the presence of 1 or 100 mg dm -3 of Aldrich humic acid had little effect on the distribution ratio of neptunium, it caused a lowering of the measured diffusion coefficient. This is interpreted in terms of the limiting liquid phase diffusion coefficient and the true liquid phase impedance factor of neptunium-humic acid complexes. 21 figs; 3 tabs; 20 refs

  13. Recent advances in clay mineral-containing nanocomposite hydrogels.

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

  14. Quorum Sensing Disruption in Vibrio harveyi Bacteria by Clay Materials.

    Naik, Sajo P; Scholin, Jonathon; Ching, San; Chi, Fang; Herpfer, Marc

    2018-01-10

    This work describes the use of clay minerals as catalysts for the degradation of quorum sensing molecule N-(3-oxooctanoyl)-dl-homoserine lactone. Certain clay minerals as a result of their surface properties and porosity can catalytically degrade the quorum sensing molecule into smaller fragments. The disruption of quorum sensing by clay in a growing Gram-negative Vibrio harveyi bacteria culture was also studied by monitoring luminescence and population density of the bacteria, wherein quenching of bacterial quorum sensing activity was observed by means of luminescence reduction. The results of this study show that food-grade clays can be used as biocatalysts in disrupting bacterial activity in various media.

  15. Water diffusion in clays with added organic surfactants

    Pineda-Pinon, J; Mendoza-Lopez, M L; Manzano-RamIrez, A; Perez-Robles, J F; Vega-Duran, J T

    2007-01-01

    Tensoactive agents may decrease water absorption in clay products like adobes. They modify the characteristics of the surface of clay particles. Characterization of water diffusion through the pores of modified clays is important to apply appropriate surface modifiers and to improve their performance. We established a simple model for water diffusion in test samples of defined dimensions to estimate real physical parameters and their effect on water absorption. Adsorption mechanisms are examined based on experimental results. The fitting of the experimental data to the model provides a deep understanding of water adsorption in chemically modified clays. A better agreement between the model and the experimental data is achieved for complex molecules

  16. Development of polymer nanocomposites with regional bentonite clay

    Araujo, Edcleide M.; Leite, Amanda M.D.; Paz, Rene A. da; Medeiros, Keila M. de; Melo, Tomas J.A.; Barbosa, Josiane D.V.; Barbosa, Renata

    2011-01-01

    nanocomposites with regional bentonite clay were prepared by melt intercalation technique. The clays were studied without modification and modified with four quaternary ammonium salts. It was evidenced by X-ray diffraction that salts were incorporated into the clay structure thus confirming its organophilization. The nanocomposites were evaluated by means of thermal mechanic and flammability tests where presented properties significantly improved their pure polymers. The process of biodegradation of obtained bio nanocomposites was accelerated by the presence of clay. The produced membranes from nanocomposites have potential in the oil-water separation. (author)

  17. The use of clays as sorbents and catalysts

    McCabe, R.W.

    1998-01-01

    The paper attempts to show the structural, physical and chemical properties of clay minerals relate to their laboratory, industrial and environmental uses as sorbents and catalysts. A brief review of the formulae and structures of clays and their relationship to their chemical and physical properties follows. Clay minerals are also useful in environmental protection as they can adsorb crude oils from spills and they are used, sometimes mixed into concrete, as containment barriers for radionuclides caesium 137 and strontium 90. Clay soils can also act as natural barriers to the migration of radionuclides in the environment

  18. Rheology of Poly(N-isopropylacrylamide)-Clay Nanocomposite Hydrogels

    Lombardi, Jack; Xu, Di; Bhatnagar, Divya; Gersappe, Dilip; Sokolov, Jonathan; Rafailovich, Miriam

    2015-03-01

    The stiffness of PNIPA Gels has been reported could be significant improved by gelation with clay fillers. Here we conducted systematic rheology study of synthesized PNIPA-Clay Composites at different clay concentration, in a range from fluid to strong gel, where G'' dominant changed to G' dominant. Molecular dynamics simulation was employed to analyze the structure of composites and corresponding mechanical changes with increased clays. Where we found viscoelastic behavior become significant only 1.5 times above percolation threshold. The yield stress extrapolated from our rheology results shows good fitting to modified Mooney's theory of suspension viscosity.

  19. Influence of chemical treatment of clay to obtain polypropylene nanocomposites

    Rosa, Jeferson L.S.; Marques, Maria F.V.

    2009-01-01

    Commercial clay was chemically treated to prepare a Ziegler-Natta catalyst containing MgCl 2 and clay for the synthesis of polypropylene nanocomposites by in situ polymerization. The performance of this catalyst and materials obtained in propylene polymerization was compared with a reference catalyst (without clay) and with another, whose composition presents the same clay but without prior chemical treatment. Techniques like differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and melt flow index (MFI) measurements were performed. There was a marked reduction in catalytic activity of clay catalysts in comparison with the reference one, and a slight reduction in melting temperature of the polymers produced from first ones. The melt flow index of polymers obtained with treated clay were notably higher than those synthesized with the untreated clay, so the treated clay caused treated the production of PP's with lower molar mass. The clays showed an increase of spacing and irregular stacking of the lamellas, especially if chemically treated. (author)

  20. Clays and Clay Minerals and their environmental application in Food Technology

    del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

    2013-04-01

    The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

  1. Consequences of the Thermal Transient on the Evolution of the Damaged Zone Around a Repository for Heat-Emitting High-Level Radioactive Waste in a Clay Formation: a Performance Assessment Perspective

    Yu, Li; Weetjens, Eef; Sillen, Xavier; Vietor, Tim; Li, Xiangling; Delage, Pierre; Labiouse, Vincent; Charlier, Robert

    2014-01-01

    A proper evaluation of the perturbations of the host rock induced by the excavation and the emplacement of exothermic wastes is essential for the assessment of the long-term safety of high-level radioactive waste disposals in clay formations. The impact of the thermal transient on the evolution of the damaged zone (DZ) has been explored in the European Commission project TIMODAZ (thermal impact on the damaged zone around a radioactive waste disposal in clay host rocks, 2006-2010). This paper integrates the scientific results of the TIMODAZ project from a performance assessment (PA) point of view, showing how these results support and justify key PA assumptions and the values of PA model parameters. This paper also contextualises the significance of the thermal impact on the DZ from a safety case perspective, highlighting how the project outcomes result into an improved understanding of the thermo-hydro-mechanical behaviour of the clay host rocks. The results obtained in the TIMODAZ project strengthen the assessment basis of the safety evaluation of the current repository designs. There was no evidence throughout the TIMODAZ experimental observations of a temperature-induced additional opening of fractures nor of a significant permeability increase of the DZ. Instead, thermally induced plasticity, swelling and creep seem to be beneficial to the sealing of fractures and to the recovery of a very low permeability in the DZ, close to that of an undisturbed clay host rock. Results from the TIMODAZ project indicate that the favourable properties of the clay host rock, which guarantee the effectiveness of the safety functions of the repository system, are expected to be maintained after the heating-cooling cycle. Hence, the basic assumptions usually made in PA calculations so far are expected to remain valid, and the performance of the system should not be affected in a negative way by the thermal evolution of the DZ around a radioactive waste repository in clay host rock.

  2. Impact of Air Oxidation on Dissolved Organic Matter from Boom Clay: Comparison Between Natural and Artificial Oxidation Series and In Situ Piezometers Water From Hades Galleries

    Blanchart, Pascale; Faure, Pierre; Michels, Raymond; Bruggeman, Christophe; De Craen, Mieke; Parant, Stephane

    2012-01-01

    Document available in extended abstract form only. The Boom Clay is considered by the Belgian radioactive waste management agency Ondraf/Niras as a possible host rock for the geological disposal of high-level and long-lived radioactive waste. The drilling of galleries and corings in the Boom Clay (Mol, Belgium) leads to perturbations of the initial physical and chemical conditions. In piezometers, the DOC may show considerable and irregular variations through time, with values ranging from 80 to 425 mg/L. The origin and bio-physico-chemical controls of such variations are yet unknown but oxidation and biodegradation were considered as most likely. Three categories of samples were collected with the aim of determining and quantifying different molecular markers representative for the oxidation process: - Fresh as well as air-oxidized Boom Clay samples were collected in the Underground Research Facility HADES of EURIDICE (Mol, Belgium): they represent a natural series of oxidation; - A fresh Boom Clay sample was submitted to laboratory air oxidation (artificial series). In these experiments, powdered clay was heated at 80 deg. C under air flow during 1, 3, 6, 9, 12, 18 months; - Four water samples were collected during January 2010 from different horizons in the Boom Clay by means of piezometers located in the Underground Research Facility. The DOM (dissolved organic matter) of Boom Clay samples (artificial and natural series) was isolated by Soxhlet using pure water as well as by leaching experiments. The quantitative analysis shows an increasing in DOC (Dissolved Organic Carbon) content with oxidation. Qualitative characterizations including spectroscopic (3D-fluorescence) as well as molecular analyses (flash pyrolysis - gas chromatography - mass spectrometry (PyGC-MS) and size exclusion chromatography (SEC-HPLC)) show an evolution of the DOM chemistry with oxidation: - An enrichment in oxygen bearing molecules (acidic poly functional groups); - A decrease in

  3. Behavior of clay materials under ionizing radiation

    Laine, Maxime

    2017-01-01

    The aim of this PhD thesis is to study and understand, by proposing reaction mechanisms, the behavior under irradiation of various clay materials. The systems of interest were first synthetic talc, which is the prototype of a non-swelling material. Under irradiation by accelerated electrons, the production of dihydrogen in this system, due solely to surface hydroxyl groups, is of the same order of magnitude as the one obtained in liquid water. This yield is divided by 30 in the case of natural talc from Luzenac, thus highlighting the importance of the impurities as scavengers of the precursors of dihydrogen. Synthetic smectites, which are swelling materials, were then studied. The results evidence the radiolysis of water confined in the interlayer space, leading to H 2 yields which may be two to three times higher than those measured in water. Moreover, they are similar for montmorillonite and saponite, evidencing that the charge location plays only a minor role. Finally, the study of double layered hydroxides or anionic clays shows that, in this case, the nature of the anion in the inter lamellar space controls the reactivity. Parallel to these measurements, electron paramagnetic spectroscopy experiments have enabled proposing reaction mechanisms. Finally, all these results are of interest in the context of the disposal of radioactive waste. (author) [fr

  4. Halloysite Clay Nanotubes for Enzyme Immobilization.

    Tully, Joshua; Yendluri, Raghuvara; Lvov, Yuri

    2016-02-08

    Halloysite clay is an aluminosilicate nanotube formed by rolling flat sheets of kaolinite clay. They have a 15 nm lumen, 50-70 nm external diameter, length of 0.5-1 μm, and different inside/outside chemistry. Due to these nanoscale properties, they are used for loading, storage, and controlled release of active chemical agents, including anticorrosions, biocides, and drugs. We studied the immobilization in halloysite of laccase, glucose oxidase, and lipase. Overall, negatively charged proteins taken above their isoelectric points were mostly loaded into the positively charged tube's lumen. Typical tube loading with proteins was 6-7 wt % from which one-third was released in 5-10 h and the other two-thirds remained, providing enhanced biocatalysis in nanoconfined conditions. Immobilized lipase showed enhanced stability at acidic pH, and the optimum pH shifted to more alkaline pH. Immobilized laccase was more stable with respect to time, and immobilized glucose oxidase showed retention of enzymatic activity up to 70 °C, whereas the native sample was inactive.

  5. Halloysite nanotubule clay for efficient water purification.

    Zhao, Yafei; Abdullayev, Elshad; Vasiliev, Alexandre; Lvov, Yuri

    2013-09-15

    Halloysite clay has chemical structure similar to kaolinite but it is rolled in tubes with diameter of 50 nm and length of ca. 1000 nm. Halloysite exhibits higher adsorption capacity for both cationic and anionic dyes because it has negative SiO2 outermost and positive Al2O3 inner lumen surface; therefore, these clay nanotubes have efficient bivalent adsorbancy. An adsorption study using cationic Rhodamine 6G and anionic Chrome azurol S has shown approximately two times better dye removal for halloysite as compared to kaolin. Halloysite filters have been effectively regenerated up to 50 times by burning the adsorbed dyes. Overall removal efficiency of anionic Chrome azurol S exceeded 99.9% for 5th regeneration cycle of halloysite. Chrome azurol S adsorption capacity decreases with the increase of ionic strength, temperature and pH. For cationic Rhodamine 6G, higher ionic strength, temperature and initial solution concentration were favorable to enhanced adsorption with optimal pH 8. The equilibrium adsorption data were described by Langmuir and Freundlich isotherms. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Geotechnical and mineralological Konyaalti (Antalya, Turkey) clays

    Acar, Mustafa Hilami; Uzer, A.U.; Altunsoy, M.

    2008-01-01

    Geotechnical and mineralogical characteristics of blue-green clays of the Harbour District existing inside the boundaries of Antalya Konyaalti Municipality were investigated with comprehensive field and laboratory tests. Today, building construction in this district is carried out without any prior qualified geotechnical investigations taking place. Undisturbed and disturbed soil specimens were taken from 12 drilled boreholes at 1.5 m intervals and down 30 m deep. Shelby tubes samples were retrieved and SPT were carried out in order to determine soil profile and geotechnical properties. After comparing the laboratory and field test results, it was observed that they were in agreement. Strength and compressibility characteristics of the soil were defined with the correlations using laboratory and field test results. Since the region has been formed of lagoon-sedimented clays, rock analysis was done on two specimens achieved from various depths along the soil profile. XRD analyses on eleven specimens were also conducted. Unconfined compressive strength (qu), undrained cohesion (Cu) and compression index (Cc) varies between 40 kN/m2, 7.0 kN/m2 and 90 kN/m2, 0.095 and 0.38, respectively. (author)

  7. Kaolinitic clay-based grouting demonstration

    McCloskey, A.L.; Barry, C.J.; Wilmoth, R.

    1997-01-01

    An innovative Kaolinitic Clay-Based Grouting Demonstration was performed under the Mine Waste Technology Program (MWTP), funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by the EPA and the U.S. Department of Energy (DOE). The objective of the technology was to demonstrate the effectiveness of kaolinitic clay-based grouting in reducing/eliminating infiltration of surface and shallow groundwater through fractured bedrock into underground mine workings. In 1993, the Mike Horse Mine was selected as a demonstration site for the field implementation and evaluation of the grouting technology. The mine portal discharge ranged between 114 to 454 liters per minute (30 to 120 gpm) of water containing iron, zinc, manganese, and cadmium at levels exceeding the National Drinking Water Maximum Contaminant Levels. The grout formulation was designed by the developer Morrison Knudsen Corporation/Spetstamponazhgeologia (MK/STG), in May 1994. Grout injection was performed by Hayward Baker, Inc. under the directive of MSE Technology Applications, Inc. (MSE-TA) during fall of 1994. The grout was injected into directionally-drilled grout holes to form a grout curtain at the project site. Post grout observations suggest the grout was successful in reducing the infiltration of the surface and shallow groundwater from entering the underground mine workings. The proceeding paper describes the demonstration and technology used to form the subsurface barrier in the fracture system

  8. Quantum-chemical modeling of smectite clays

    Aronowitz, S.; Coyne, L.; Lawless, J.; Rishpon, J.

    1982-01-01

    A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors.

  9. Organically modified clay removes oil from water

    Alther, G.R.

    1995-01-01

    When bentonite or other clays and zeolite are modified with quaternary amines, they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease, and other sparingly soluble organics. Types of oil found in water can include fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, diesel oils; and light hydrocarbons such as kerosene, jet fuel, and gasoline. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOGs (Free Oil and Grease) and chlorinated hydrocarbons. In this application the clay is mixed with anthrazite to prevent early plugging of the filter by oil or grease droplets. In batch systems a powdered organoclay is employed. Organoclay removes mechanically emulsified oil and grease at 5--7 times the rate of activated carbon, or 50% of its dry weight. Oil and grease and other large sparingly soluble chlorinated hydrocarbons and NOMs (Natural Organic Matter) blind the pores of activated carbon (and ion-exchange resins), reducing its effectiveness significantly. It is therefore economically advantageous for the end user to prepolish the water before it enters carbon vessels. Operating costs can often be reduced by 50% or more

  10. CLAY SOIL STABILISATION USING POWDERED GLASS

    J. OLUFOWOBI

    2014-10-01

    Full Text Available This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the results, the soil sample obtained corresponded to Group A-6 soils identified as ‘fair to poor’ soil type in terms of use as drainage and subgrade material. This justified stabilisation of the soil. Thereafter, compaction, California bearing ratio (CBR and direct shear tests were carried out on the soil with and without the addition of the powdered glass. The results showed improvement in the maximum dry density values on addition of the powdered glass and with corresponding gradual increase up to 5% glass powder content after which it started to decrease at 10% and 15% powdered glass content. The highest CBR values of 14.90% and 112.91% were obtained at 5% glass powder content and 5mm penetration for both the unsoaked and soaked treated samples respectively. The maximum cohesion and angle of internal friction values of 17.0 and 15.0 respectively were obtained at 10% glass powder content.

  11. Geosynthetic clay liners - slope stability field study

    Carson, D.A.; Daniel, D.E.; Koerner, R.M.; Bonaparte, R.

    1997-01-01

    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project

  12. Obtention of chemically modified clays: organovermiculites

    Santana, Lisiane N.L.; Silva, Andrea L.; Barbosa, Estefane; Neves, Gelmires A.; Menezes, Romualdo Rodrigues

    2012-01-01

    The organovermiculite is obtained by incorporating the quaternary ammonium salt in the clay mineral vermiculite interlayer space. The objective of this work was to prepare organovermiculites for applications in organic contaminants adsorption. The variation of interlayer space was determined when the vermiculite was treated with an ionic salt (Praepagem WB) and a non-ionic salt (Amina Etoxilada TA50) in different concentrations. Before interacting with quaternary ammonium salt, the clay mineral was subjected to cationic change process with Na 2 CO 3 to substitute Mg 2+ by Na + . The results showed enlargement of interlayer space, reaching values up to 60.0 Å. The vermiculite pre-activated with Na 2 CO 3 during 5 days and modified with the Praepagem WB showed the best performance. Amina Etoxilada TA50 salt was not observed significant changes with increasing concentration. The affinity of organovermiculite for organic solvents was confirmed by Foster swelling test and the best results were observed with diesel and petrol as solvents. (author)

  13. Thermal conductivity of unsaturated clay-rocks

    D. Jougnot

    2010-01-01

    Full Text Available The parameters used to describe the electrical conductivity of a porous material can be used to describe also its thermal conductivity. A new relationship is developed to connect the thermal conductivity of an unsaturated porous material to the thermal conductivity of the different phases of the composite, and two electrical parameters called the first and second Archie's exponents. A good agreement is obtained between the new model and thermal conductivity measurements performed using packs of glass beads and core samples of the Callovo-Oxfordian clay-rocks at different saturations of the water phase. We showed that the three model parameters optimised to fit the new model against experimental data (namely the thermal conductivity of the solid phase and the two Archie's exponents are consistent with independent estimates. We also observed that the anisotropy of the effective thermal conductivity of the Callovo-Oxfordian clay-rock was mainly due to the anisotropy of the thermal conductivity of the solid phase.

  14. Optimization of lining design in deep clays

    Rousset, G.; Bublitz, D.

    1989-01-01

    The main features of the mechanical behaviour of deep clay are time dependent effects and also the existence of a long term cohesion which may be taken into account for dimensioning galleries. In this text, a lining optimization test is presented. It concerns a gallery driven in deep clay, 230 m. deep, at Mol (Belgium). We show that sliding rib lining gives both: - an optimal tunnel face advance speed, a minimal closure of the gallery wall before setting the lining and therefore less likelihood of failure developing inside the rock mass. - limitation of the length of the non-lined part of the gallery. The chosen process allows on one hand the preservation of the rock mass integrity, and, on the other, use of the confinement effect to allow closure under high average stress conditions; this process can be considered as an optimal application of the convergence-confinement method. An important set of measurement devices is then presented along with results obtained for one year's operation. We show in particular that stress distribution in the lining is homogeneous and that the sliding limit can be measured with high precision

  15. Safety- and performance indicators for a generic deep geological repository in clay

    Resele, G.; Niemeyer, M.; Wilhelm, St.; Heimer, St.; Mohlfeld, M.; Eilers, G.; Preuss, J.; Wollrath, J.

    2010-01-01

    Document available in extended abstract form only. As a first step of an impartial survey for an optimal site selection for a deep geological repository in Germany, potentially suitable regions shall be identified and localised according to their suitability. During the early phases of such a site selection procedure the information about the properties of the host rock and the geological situation at the potential sites is not very precise. As site investigation procedures are both expensive and time-consuming, it is essential to identify those properties of the geological barrier system that are most relevant for long-term safety. Furthermore, adequate indicators have to be chosen that allow a simple but efficient assessment of the suitability of the potential regions. Definition and application of 'exclusion criteria' based on single parameter values, e.g. the hydraulic conductivity of the host rock, is inadequate because the long-term safety depends on the interaction of many features and properties of the barrier system. In a research project, indicators have been developed which depend on the most relevant properties of the geological barriers and estimate the overall performance of a repository system. The application of these indicators on the barrier properties which have been found during the investigations of potential repository sites in clay located in Germany, Switzerland and France demonstrates how, for instance, an unfavourably high hydraulic permeability of the clay can be compensated by a large vertical extension of the clay layer and small hydraulic gradients. Other indicators evaluate the importance of hydraulic discontinuities and define the minimal requirements on technical barriers like seals and backfill of emplacement tunnels. When the information of the radionuclide inventory and the biosphere, especially the diluting aquifer is included, the indicators allow the estimation of the resulting dose which matches the result of a

  16. Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

    Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

    2002-07-01

    In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

  17. Toxicological evaluation of clay minerals and derived nanocomposites: a review.

    Maisanaba, Sara; Pichardo, Silvia; Puerto, María; Gutiérrez-Praena, Daniel; Cameán, Ana M; Jos, Angeles

    2015-04-01

    Clays and clay minerals are widely used in many facets of our society. This review addresses the main clays of each phyllosilicate groups, namely, kaolinite, montmorillonite (Mt) and sepiolite, placing special emphasis on Mt and kaolinite, which are the clays that are more frequently used in food packaging, one of the applications that are currently exhibiting higher development. The improvements in the composite materials obtained from clays and polymeric matrices are remarkable and well known, but the potential toxicological effects of unmodified or modified clay minerals and derived nanocomposites are currently being investigated with increased interest. In this sense, this work focused on a review of the published reports related to the analysis of the toxicological profile of commercial and novel modified clays and derived nanocomposites. An exhaustive review of the main in vitro and in vivo toxicological studies, antimicrobial activity assessments, and the human and environmental impacts of clays and derived nanocomposites was performed. From the analysis of the scientific literature different conclusions can be derived. Thus, in vitro studies suggest that clays in general induce cytotoxicity (with dependence on the clay, concentration, experimental system, etc.) with different underlying mechanisms such as necrosis/apoptosis, oxidative stress or genotoxicity. However, most of in vivo experiments performed in rodents showed no clear evidences of systemic toxicity even at doses of 5000mg/kg. Regarding to humans, pulmonary exposure is the most frequent, and although clays are usually mixed with other minerals, they have been reported to induce pneumoconiosis per se. Oral exposure is also common both intentionally and unintentionally. Although they do not show a high toxicity through this pathway, toxic effects could be induced due to the increased or reduced exposure to mineral elements. Finally, there are few studies about the effects of clay minerals on

  18. Corrosion behaviour of carbon steel in the Tournemire clay

    Foct, F.; Dridi, W.; Cabrera, J.; Savoye, S.

    2004-01-01

    Carbon steels are possible materials for the fabrication of nuclear waste containers for long term geological disposal in argillaceous environments. Experimental studies of the corrosion behaviour of such materials has been conducted in various conditions. Concerning the numerous laboratory experiments, these conditions (water and clay mixture or compacted clay) mainly concern the bentonite clay that would be used for the engineered barrier. On the opposite, only few in-situ experiments has been conducted directly in the local clay of the repository site (such as Boom clay, etc.). In order to better estimate the corrosion behaviour of carbon steels in natural clay site conditions, an experimental study has been conducted jointly by EDF and IRSN in the argillaceous French site of Tournemire. In this study, A42 carbon steel specimens have been exposed in 3 different zones of the Tournemire clay formation. The first type of environmental conditions concerns a zone where the clay has not been affected by the excavation (EDZ) of the main tunnel neither by the main fracture zone of the clay formation. The second and third ones are located in the EDZ of the tunnel. In the second zone, an additional aerated water flows from the tunnel, whereas it does not in the third place. Some carbon steel specimens have been extracted after several years of exposure to these conditions. The average corrosion rate has been measured by the weight loss technique and the pitting corrosion depth has been evaluated under an optical microscope. Corrosion products have also been characterised by scanning electron microscopy and X-ray diffraction technique. Results are then discussed regarding the surrounding environmental conditions. Calculations of the oxygen transport from the tunnel through the clay and of the clay re-saturation can explain, in a first approach, the corrosion behaviour of the carbon steel in the different tested zones. (authors)

  19. Impact-Induced Clay Mineral Formation and Distribution on Mars

    Rivera-Valentin, E. G.; Craig, P. I.

    2015-01-01

    Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

  20. Effects of biochar on hydraulic conductivity of compacted kaolin clay.

    Wong, James Tsz Fung; Chen, Zhongkui; Wong, Annie Yan Yan; Ng, Charles Wang Wai; Wong, Ming Hung

    2018-03-01

    Compacted clay is widely used as capillary barriers in landfill final cover system. Recently, biochar amended clay (BAC) has been proposed as a sustainable alternative cover material. However, the effects of biochar on saturated hydraulic conductivity (k sat ) of clay with high degree of compaction is not yet understood. The present study aims to investigate the effects of biochar on k sat of compacted kaolin clay. Soil