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Sample records for argillite

  1. Thermo-hydro-mechanical behavior of argillite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Argillite is a very low permeability geo-material widely encountered: that is the reason why it is an excellent candidate for the storage of long-term nuclear waste depositories. This study focuses on argillites from Meuse-Haute-Marne (East of France) which forms a geological layer located approximately 400 m and 500 m depth. We know that this material is made up of a mixture of shale, quartz and calcite phases. The multi-scale definition of this material suggests the derivation of micro-mechanics reasonings in order to better account for the mechanisms occurring at the local (nano and micro-) scale and controlling the macroscopic mechanical behavior. In this work, up-scaling techniques are used in the context of thermo-hydro-mechanical couplings. The first step consists in clarifying the morphology of the microstructure at the relevant scales (particles arrangement, pore size distribution) and identifying the mechanisms that take place at those scales. These local informations provide the input data of micro-mechanics based models. Schematic picture of the microstructure where the argillite material behaves as a dual-porosity, with liquid in both micro-pores and interlayer space in between clay solid platelets, seems a reasonable starting point for this micro-mechanical modelling of clay. This allows us to link the physical phenomena (swelling clays) and the mechanical properties (elastic moduli, Poisson's ratio). At the pressure applied by the fluid on the solid platelets appears as the sum of the uniform pressure in the micro-pores and of a swelling overpressure depending on the distance between platelets and on the ion concentration in the micro-pores. The latter is proved to be responsible for a local elastic modulus of physical origin. This additional elastic component may strongly be influenced by both relative humidity and temperature. A first contribution of this study is to analysing this local elastic

  2. Generic Argillite/Shale Disposal Reference Case

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Liange; Colon, Carlos Jové; Bianchi, Marco; Birkholzer, Jens

    2014-08-08

    Radioactive waste disposal in a deep subsurface repository hosted in clay/shale/argillite is a subject of widespread interest given the desirable isolation properties, geochemically reduced conditions, and widespread geologic occurrence of this rock type (Hansen 2010; Bianchi et al. 2013). Bianchi et al. (2013) provides a description of diffusion in a clay-hosted repository based on single-phase flow and full saturation using parametric data from documented studies in Europe (e.g., ANDRA 2005). The predominance of diffusive transport and sorption phenomena in this clay media are key attributes to impede radionuclide mobility making clay rock formations target sites for disposal of high-level radioactive waste. The reports by Hansen et al. (2010) and those from numerous studies in clay-hosted underground research laboratories (URLs) in Belgium, France and Switzerland outline the extensive scientific knowledge obtained to assess long-term clay/shale/argillite repository isolation performance of nuclear waste. In the past several years under the UFDC, various kinds of models have been developed for argillite repository to demonstrate the model capability, understand the spatial and temporal alteration of the repository, and evaluate different scenarios. These models include the coupled Thermal-Hydrological-Mechanical (THM) and Thermal-Hydrological-Mechanical-Chemical (THMC) models (e.g. Liu et al. 2013; Rutqvist et al. 2014a, Zheng et al. 2014a) that focus on THMC processes in the Engineered Barrier System (EBS) bentonite and argillite host hock, the large scale hydrogeologic model (Bianchi et al. 2014) that investigates the hydraulic connection between an emplacement drift and surrounding hydrogeological units, and Disposal Systems Evaluation Framework (DSEF) models (Greenberg et al. 2013) that evaluate thermal evolution in the host rock approximated as a thermal conduction process to facilitate the analysis of design options. However, the assumptions and the

  3. Ten years of Toarcian argillite - carbon steel in situ interaction

    Energy Technology Data Exchange (ETDEWEB)

    Dauzeres, Alexandre [IRSN, PRP-DGE/SRTG/LETIS, BP 17, 92262 Fontenay-aux-Roses cedex (France); Maillet, Anais [IRSN, PRP-DGE/SRTG/LETIS, BP 17, 92262 Fontenay-aux-Roses cedex (France); UMR CNRS 7285, IC2MP, Batiment B35 - 5, avenue Albert Turpain, 86022 Poitiers cedex (France); Gaudin, Anne [UMR CNRS 6112, LPGN, 2 rue de la Houssiniere, BP 92208, 44322 Nantes cedex 3 (France); El Albani, Abderrazak; Vieillard, Philippe [UMR CNRS 7285, IC2MP, Batiment B35 - 5, avenue Albert Turpain, 86022 Poitiers cedex (France)

    2013-07-01

    In situ interaction experiments over periods of 2, 6, and 10 years between Toarcian argillite and carbon steel discs were carried out in the Tournemire Underground Research Laboratory (URL), yielding a dataset of the materials' geochemical evolution under conditions representative of the future geological disposal of high-level long-lived radioactive wastes. The carbon steel discs were exposed to corrosion due to trapped oxygen. The corrosion rates indicate that the oxidizing transient lasted between 2 and 6 years. A systematic dissolution of calcium phases (Ca-smectite sheets in I/S and calcite) was observed in the iron diffusion halos. The iron release induced mineralogical dissolution and precipitation reactions, which partly clogged the argillite porosity. (authors)

  4. Bundled slaty cleavage in laminated argillite, north-central minnesota

    Science.gov (United States)

    Southwick, D.L.

    1987-01-01

    Exceptional bundled slaty cleavage (defined herein) has been found in drill cores of laminated, folded, weakly metamorphosed argillite at several localities in the early Proterozoic Animikie basin of north-central Minnesota. The cleavage domains are more closely spaced within the cleavage bundles than outside them, the mean tectosilicate grain size of siltstone layers, measured normal to cleavage, is less in the cleavage bundles than outside them, and the cleavage bundles are enriched in opaque phases and phyllosilicates relative to extra-bundle segments. These facts suggest that pressure solution was a major factor in bundle development. If it is assumed that opaque phases have been conserved during pressure solution, the modal differences in composition between intra-bundle and extra-bundle segments of beds provide a means for estimating bulk material shortening normal to cleavage. Argillite samples from the central part of the Animikie basin have been shortened a minimum of about 22%, as estimated by this method. These estimates are similar to the shortening values derived from other strain markers in other rock types interbedded with the argillite, and are also consistent with the regional pattern of deformation. ?? 1987.

  5. In situ Tournemire argillite / iron metal interactions: results after 10 years

    International Nuclear Information System (INIS)

    Within the framework of a long lived radioactive waste storage concept in deep geological layer developed by Andra, IRSN leads an in situ study on the Experimental Station of Tournemire, in association with EDF to determine the interactions steel/argillite in a natural context. After 10 years of interaction, two drillings overcoring performed to characterize the processing of the Tournemire argillite in contact with carbon and stainless steels and to compare reactive phenomena highlighted and those induced by simulations tools combining chemistry and transport. Argillite/carbon steel samples show a significant corrosion of steel disk. Iron released, in the form of rings and cracks in the rock, disrupts the argillite in contact resulting in mineralogical and structural changes. Iron oxides precipitation and a calcite and smectitic leaf of mixed-layers I/S dissolution are identified. A succession of areas: metal/metal corroded/argillite disturbed/argillite is highlighted and porosity variations are observed on the interfaces between two areas. Geochemical simulations show that major changes are initiated speedily during establishment of the system and the oxygen trapped in the closed system is consumed by the corrosion of steel but mostly it diffuses into the surrounding material through concentration gradient. Argillite/stainless steel samples have a very low pitting corrosion of steel disk. This does not seem to affect the mineralogy of the argillite in contact. (author)

  6. Influence of steel corrosion on Tournemire argillite after 10 years under natural underground context

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Carbon steels are possible materials for high-level radioactive waste canisters used in long term geological disposal in argillaceous environments. The French Institute of Radioprotection and Nuclear Safety (IRSN) conducts, in collaboration with EDF, an experimental program on steel/argillite interactions under natural conditions in its Underground Research Facility in Tournemire (Aveyron, France). Previous studies had investigated the corrosion rate of carbon steel (Foct et al., 2004; Foct, 2006) and modifications of the argillite (Gaudin et al., 2009) after 2 and 6 years of contact. The present study investigates re-compacted argillite/carbon steel interactions far from mechanical disturbances without water flow, after 10 years. A detailed study by X-ray microtomography (Stock, 2009) and autoradiography (Hellmuth et al., 1994) allowed us to characterize the spatial dispersion of Fe and its influence on the evolution of argillite porosity. A significant corrosion of the carbon steel sample and the development of a reddish Fe-rich front within the argillite resulting from an iron diffusion is observed. The formation of iron oxy-hydroxides (goethite, magnetite and hematite) is identified in the altered argillite. Other mineralogical changes are highlighted such as dissolution of calcite, gypsum precipitation and modification of I/S mixed-layers. The Fe distribution within the argillite at the contact appears heterogeneous. Reddish Fe-enriched haloes of maximum 4 mm within the argillite are observed macroscopically (Figure 1a) and by X-ray microtomography. Moreover, autoradiography measurements were performed and changes in porosity are observed from carbon steel to argillite (Figure 1c). The correlation with the microtomography image (Figure 1b) shows that these variations can be associated to iron diffusion areas. On the other hand, a porosity profile shows four distinct areas differing by their mean porosity: (1

  7. Evidence and identification of microorganisms in argillite from Tournemire (France)

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Generalised corrosion is one of the main processes taken into account in the dimensioning of non-alloy steel overpacks for high level nuclear waste packages. However, the presence of microorganisms such as sulfate-reducing bacteria in the host rock in contact with these non-alloy materials may also influence localised corrosion processes, leading to a premature loss of the overpack watertightness. Available void and presence of free water are key conditions for bacterial development, which are not often met in an argillaceous environment. Nevertheless, microbial activity has been proven to occur in argillaceous formations such as the Opalinus Clay in the Mont Terri Underground Research Laboratory. Indigenous sulfate-reducing bacteria have also been put into evidence in MX-80 bentonite, a clayey material likely to be used as engineered barrier in many countries for nuclear waste repositories. The French Institute of Radioprotection and Nuclear Safety (IRSN) has been conducting a research program at the Tournemire experimental platform on the biodiversity of Toarcian argillite, aiming at assessing the potential development of a microbial activity in deep clayey environments, disturbed or not by an excavation. The occurrence of microbial processes in this formation was first shown by the study of time evolution of the chemical and isotopic composition of fracture groundwaters collected in several boreholes. These investigations suggested that aqueous sulfates and their isotopic composition were controlled by bacterial sulfate reduction. The presence of living sulfate-reducing bacteria in water samples from an air-drilled borehole crossing a tectonic fracture (MB1) was later shown. Thus, a characterisation of the microbial biodiversity of the Toarcian argillite was launched. Samples have been collected in different locations of the Tournemire experimental platform: pieces of wall of the gallery, as well as cores from

  8. Low Temperature Pyrolysis of Graptolite Argillite (Dictyonema Shale in Autoclaves

    Directory of Open Access Journals (Sweden)

    Galina Sharayeva

    2015-11-01

    Full Text Available The results of the systematic experimental study obtained in this work on the effects of temperature (340–420 °C and exposure time (0–8h at nominal temperature on the yield of pyrolysis products from Estonian graptolite argillite (GA generated in autoclaves without any solvent are described. The yields of solid residue (SR, gas, pyrogenetic water (W and extractable with benzenemix ofthermobitumen and oil (TBO were estimated. The compound groups of TBO were assessed. The highest yield of TBO, 2.18% on dry GA basis and 13.2% of organic matter (OM was obtained at temperature of 420 °C and duration 0.5 h. The main compound groups in TBO obtained at 400 ᵒC are polar hetero-atomic compounds and polycyclic hydrocarbons surpassing 45% and 30% of TBO. The shares of aliphatic and monocyclic hydrocarbons are below 15% of TBO. The yield of W from GA is – about 10-15% of OM. The quantity of OM left in SR after pyrolysis is high, about 65% of OM. The yield of pyrolysis products from GA and the composition of its TBO are compared with those obtained under similar conditions from different oil shales: Estonian Kukersite, US Utah Green River, and Jordanian Attarat.

  9. Experimental evidence for self-sealing of fractures in argillites

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In argillaceous rocks, self-sealing of fractures generated by the excavation of underground repositories can be expected due to combined impact of rock compression, backfill resistance, and clay swelling during the post-closure phase. The sealing process is determined by the deformability and swelling capacity of the host rock and the backfill as well as by the boundary conditions. As a crucial factor for the long-term safety of repositories, the sealing behaviour of fractures in argillites has been experimentally investigated by GRS on the Callovo-Oxfordian argillite (COX) and the Opalinus clay (OPA) under relevant repository conditions. Comprehensive laboratory tests were carried out on artificially-fractured samples of different sizes (diameter/length = 50/50 - 280/600 mm) and shapes (cylinder and hollow cylinder) under various confining stresses, fluid pressures, and temperatures. The sealing of fractures was detected by measurement of deformation, permeability and wave velocity variations. Following previous studies in which the sealing of fractured samples was determined by gas flow at ambient temperature, additional tests were performed by flowing synthetic pore water through fractures under different confining stresses and at elevated temperatures. Typical results of the tests are presented in this paper. Current results of the ongoing long-term permeability measurements on fractured COX and OPA samples (D/L = 50/50 mm) are summarized, some of which were pre-heated up to high temperatures of 50, 100 and 150 deg. C. In those tests, synthetic pore water was flowed through at injection pressure of 1 MPa, confining stresses of 2 to 3 MPa, and elevated temperatures from 20 to 90 deg. C. All fractured samples showed the same high initial gas permeability of 3.10-12 m2. As the water was injected, the permeability dropped down by three to five orders of magnitude to 10-15 to 10-18 m2, depending on the intensity of

  10. Micro-mechanics based modeling of the Callovo-Oxfordian argillite mechanical behavior

    International Nuclear Information System (INIS)

    The present study is devoted to the development and validation of a non-linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as an heterogeneous one composed of an elastoplastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the Hill-type incremental method [1]. The approach consists in formulating the macroscopic tangent operator of the material from the non-linear local behavior of its phases. Due to the matrix/inclusion morphology of the microstructure of the argillites, a Mori-Tanaka scheme is considered for the localization step. The developed model is first compared to Finite-Elements calculations and then validated and applied for the prediction of the macroscopic stress-strain responses of argillites. (authors)

  11. Distribution regularities and prospecting of carbonate-siliceous-argillitic rock type uranium deposit in China

    International Nuclear Information System (INIS)

    The carbonate-siliceous-argillitic rock type uranium deposit is one of the important types of uranium deposits in China. Exogenic permeability type and hydrothermal type are dominated in genetic type. Four mineralization zones, two independent mineralization districts, two potential mineralization zones can be classified in China, uranium mineralization districts can be classified further. They are classified as four levels through the potential metallogenic evaluation on the mineralization districts, an important prospective area in the near future. In order to develop and make use of carbonate-siliceous-argillitic rock type uranium resources, exploration and study should be listed in the development planning on uranium geology. (authors)

  12. Complexation of europium(III) by organic extracts from Callovo-Oxfordian argillites

    Energy Technology Data Exchange (ETDEWEB)

    Brevet, L.; Grasset, L.; Ambles, A. [Univ. de Poitiers, Synthese et Reactivi te des Substances Naturelles, CNRS UMR 6514, 86022 Poitiers (France); Reiller, P.; Claret, F.; Amekraz, B.; Moulin, C. [CEA, CE Saclay, CEA/DEN/DANS/DPC/SECR, Labo ratoire de Speciation des Radionucleides et des Molecules, F-91191 Gif-sur-Yvette (France)

    2007-06-15

    The complexation behaviour of organic extracts obtained after acid alteration of Callovo-Oxfordian argillites toward europium (III) is studied in time resolved laser induced spectrofluorimetry. The presence of fluoride ions in one extract, originated from the dissolution of remaining silicates in HCl/HF, precludes the correct study. Nevertheless, the dialysis of the extract at 500 Da permits to obtain a clearer evolution of the complexation pattern. The fluorescence spectrum and decay are strikingly different the ones obtained on alkaline degradation products of the Callovo-Oxfordian argillite, and resemble more to a small organic molecule pattern.

  13. Preliminary inventory of pre-Cenozoic clay shales and argillites of the conterminous United States

    International Nuclear Information System (INIS)

    Cretaceous shales of the Western Interior of the United States occur in vast quantities and in thickness greater than 150 m (500 ft). Some older Mesozoic, Paleozoic, and Precambrian shale and argillites also appear to approach these thicknesses in deposits of considerable lateral extent. These older rocks commonly have a lower proportion of expandable clays and lower water contents

  14. Reactive transport modeling of geochemical interactions at a concrete/argillite interface, Tournemire site (France)

    Science.gov (United States)

    De Windt, L.; Marsal, F.; Tinseau, E.; Pellegrini, D.

    Mineralogical and petrographical investigations of a borehole sealed by concrete (“engineered analogue” of concrete/clay interactions) overcored at the Tournemire site offer the possibility to perform reactive transport modeling over a timescale of 15 years, which is significantly longer than standard durations of laboratory experiments. The HYTEC code was used to simulate mineralogical evolutions in the Tournemire argillite matrix and along small fractures, as well as in concrete, assuming either thermodynamic equilibrium approach or kinetic control coupled to diffusive transfer. The mineralogical profiles calculated in thermodynamic equilibrium and with kinetics are very similar in the concrete. In contrast, kinetics of dissolution and precipitation reactions is found to be necessary for a better reproduction of the experimental observations in the argillite samples compared to thermodynamic equilibrium calculations, in particular with respect to the extent of the alkaline perturbation. The major effects observed when considering kinetics in the calculations are to smooth the sharpness and intensity of the mineralogical transformation fronts, these fronts being predicted to occur deeper inside the argillite matrix (ettringite/carbonates at the concrete/argillite interface, followed by a zone of neoformation of clay-like phases and calcite, and a last zone with precipitation of calcite. Main discrepancies between the modeling results and the experimental observations are the precipitation of muscovite instead of K-feldspar and the neoformation of zeolites. Calculations also correctly predict that carbonates form at the concrete/argillite interface, which most probably result from concrete alteration and follow Ostwald’s step rule of mineral precipitation with a predominance of metastable vaterite over calcite.

  15. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite

    International Nuclear Information System (INIS)

    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)

  16. Contributions to micromechanical model of the non linear behavior of the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    This work is performed in the general context of the project of underground disposal of radioactive waste, undertaken by the French National Radioactive Waste Management Agency (ANDRA). Due to its strong density and weak permeability, the formation of Callovo-Oxfordian argillite is chosen as one of possible geological barriers to radionuclides. The objective of the study to develop and validate a non linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as a composite constituted of an elasto(visco)plastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the incremental method proposed by Hill. The derived model is first compared to Finite Element calculations on unit cell. It is then validated and applied for the prediction of the macroscopic stress-strain responses of the argillite at different geological depths. Finally, the micromechanical model is implemented in a commercial finite element code (Abaqus) for the simulation of a vertical shaft of the underground laboratory. This allows predicting the distribution of damage state and plastic strains and characterizing the excavation damage zone (EDZ). (author)

  17. Microbial corrosion of steel in Toarcian argillite: potential influence of bio-films

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the context of a geological disposal of radioactive waste in clayey formations, the consequences of microbial activity are of concern regarding the corrosion of metallic components, such as the overpack surrounding vitrified waste. Generalized corrosion is one of the main processes taken into account in the dimensioning of these overpacks. However, the presence of microorganisms such as sulfate- or thiosulfate-reducing bacteria in the host rock in contact with these non-alloy materials may enhance localized corrosion processes, leading to a premature and undesirable loss of watertightness. Moreover, the passive corrosion layer, which is formed progressively during the generalized corrosion process and induces a decrease of corrosion rates, may react with iron-reducing bacteria and thus reactivate corrosion. The formation of bio-films may also lead to significant modifications of environment at the biofilm/metal interface in terms of pH, dissolved oxygen, organic and inorganic species, that may lead to electrochemical reactions that could potentially increase corrosion rates. There is thus a need for further investigations of the potential consequences on the physico-chemical conditions within geological disposal facilities. The French Institute for Radiological Protection and Nuclear Safety (IRSN) has been conducting research programs since 1991 in the Tournemire Underground Research Laboratory (URL), a railway tunnel which crosses a Toarcian argillaceous formation. This geological layer is particularly interesting for its physical and chemical properties close to those of Callovo-Oxfordian argillite. The importance of microbial processes in this formation was first shown by the study of time evolution of the chemical and isotopic compositions of fracture groundwaters collected in several boreholes. These investigations suggested that aqueous sulphates and their isotopic composition were controlled by bacterial

  18. Microbial diversity of the 180 million-year-old Toarcian argillite from Tournemire, France

    International Nuclear Information System (INIS)

    Even though the microbiology of various subsurface environments has been investigated for more than 30 a, the microbial diversity of deep argillaceous media is still poorly known. In the context of radioactive waste disposal in clayey formations, the consequence of microbial activity is of concern regarding e.g. the corrosion of metallic components. The purpose of the present work was to characterise the cultivable microbial diversity of different zones of the Toarcian argillite of Tournemire (France) as a preliminary indication regarding the potential of development of microbes in such subterrestrial environments. Cores were drilled in the Excavation Damaged Zone (EDZ) and in the deeper undisturbed zone of the argillite layer, as well as in a zone intersected by a geological fault. Samples from the wall of the drift were also collected. Microorganisms were cultivated from all samples, but the biodiversity differed depending mainly on the O2 and moisture content. Aerobic bacteria were identified on the wall, in the EDZ and in the wet faulted area, whereas SO4-reducing bacteria were isolated from the wet faulted area only. Anaerobic heterotrophs were cultivated from all zones. One hundred and twelve isolates were identified. Small ribosomal subunit gene sequences showed that bacteria of the undisturbed zone were affiliated to three genera only, whereas the three other sampled zones harbour more diverse microflora, including isolates closely related to taxons characterized from subsurface, deep marine and polar environments.

  19. Test results and supporting analysis of a near-surface heater experiment in the Eleana argillite

    International Nuclear Information System (INIS)

    A preliminary evaluation of the in-situ thermomechanical response of argillite to heating was obtained from a near-surface heater test in the Eleana Formation, at the United States Department of Energy, Nevada Test Site. The experiment consisted of a 3.8 kW, 3-m long x 0.3-m diameter electrical heater in a central hole surrounded by peripheral holes containing instrumentation to measure temperature, gas pressures, and vertical displacement. A thermal model of the experiment agreed well with experimental results; a comparison of measured and predicted temperatures indicates that some nonmodeled vertical transport of water and water vapor occurred near the heater, especially at early times. A mechanical model indicated that contraction of expandable clays in the argillite produced a region 1.5 - 2.0 m in radius, in which opening of preexisting joints occurred as a result of volumetric contraction. Results of thermal and mechanical modeling, laboratory property measurements, experimental temperature measurements, and post-test observations are all self-consistent and provide preliminary information on the in-situ response of argillaceous rocks to the emplacement of heat-producing nuclear waste

  20. Hydro-mechanical coupling and transport in Meuse/Haute-Marne argillite: experimental and multi-scale approaches

    International Nuclear Information System (INIS)

    This thesis deals with the hydro-mechanical behaviour of argillite. Classical Biot theory is shown to be badly adapted to the case of argillite. An original state equation is then built by use of homogenization tools, and takes into account the microstructure of argillite as well as physical phenomena happening inside the material, like the swelling overpressure inside the clay particles or the capillary effects in the porous network. This state equation explains some experiments which were not by the classical Biot theory. It is then improved by integrating the experimental data that are the dependency of the elasticity tensor with the saturation degree and the existence of a porosity surrounding the inclusions. Combined with the monitoring of length variation under hydric loading, this relevant state equation permits one to determine the Biot tensor of argillite. Since this state equation is coupled with the hydric state of the material, one is interested in modelling the variation of the saturation degree during a drying process. Two transport models are studied and compared, then a model for the porous network is proposed in order to explain the unusual permeability measurements. (author)

  1. Predicting the diagenetic evolution of argillite repositories based on the study of natural and experimental systems

    International Nuclear Information System (INIS)

    Understanding the nature of diagenetic reactions involving clays and associated mineral phases is an important aspect in predicting the long-term chemical and physical properties of host-rock argillite in underground radioactive repositories. Much of our current knowledge is based on the study of mineral phases in natural rock sequences that have formed under a range of pressure (P), temperature (T), compositional (X) and time (t) conditions (Velde, 1992). Valuable information has also been obtained by reproducing reactions in the laboratory under constrained conditions using batch or flow-through reactors (e.g. Nagy, 1995; Wogelius and Vaughan, 2000). Based on our current knowledge, six primary controls can be recognised, which drive diagenetic reactions in the upper portion of the Earth's crust. i) Fluid chemistry, providing the essential ingredients for exchange of cations and anions. ii) Rock composition, laying down the basic building blocks and reaction sites. iii) Rock permeability, necessary for allowing material transport and fluid-rock interaction. iv) Temperature, as the principle energy source for enhancing reaction rates. v) Time, needed to allow reactions to get closer to their equilibrium conditions. vi) Stress and strain, for mechanical mixing of reactants and products. In order to predict the diagenetic evolution of argillite repositories, we need to know firstly, which reactions occur under a defined set of conditions, secondly, how these reactions modify the material properties of the argillite seal, and finally, how fast these chemical reactions take place. Based on the application of thermodynamics, and the construction of activity diagrams for low temperature mineral phases (e.g. Velde, 1992), fair predictions of mineral stability can be made under a given set of physical and chemical conditions. Such predictions are strengthened by examining mineral reactions that occur under natural conditions and also those that have been preserved in the

  2. Osmotic flow and over pressures within the Callovo-Oxfordian argillite in the eastern part of the Paris Basin

    International Nuclear Information System (INIS)

    A middle Jurassic shale, the Callovo-Oxfordian argillite (420-560 m b.g.), is currently being intensively investigated at the ANDRA site, about 300 km eastern from Paris, and particularly with respect to its hydrogeological and hydrochemical properties. The argillite rests between the Oxfordian Limestone above and the Dogger Limestone below. Observations from the different deep boreholes located at the site can be summarized as follows: the measured apparent hydraulic head across the Callovo-Oxfordian argillite show excess values of several tens of meters in comparison to the upper and lower aquifers, a fact which is referred to as anomalous overpressure in the shale literature; the salinity of the pore water in the Callovo-Oxfordian argillite and the Dogger is much larger than that of the Oxfordian. The salinity levels in the Callovo-Oxfordian and the Dogger are similar. Among all physical processes which can be proposed as explanation for the formation of overpressure in shales, osmosis driven by a chemical potential (total dissolved solids) gradient is a possible candidate. As a matter of fact, the presence of contrasts in water composition and clay minerals content, as observed here, lead to osmotic effects. This paper presents the results of simulations using steady-state approximations and transient simulations (software OSMO, a numerical simulator developed by the British Geological Survey). It is shown that based on the extensive database of argillite measurements applicable to the study (including porosity values, specific surface determinations, pore water compositions, and effective diffusion coefficients), the chemo-osmosis is a process which can at least explain partly the anomalous overpressures observed. (authors)

  3. Iron/argillite interactions in radioactive waste disposal context: Oxidising transient and bacterial activities influence

    International Nuclear Information System (INIS)

    The design of a high-level radioactive waste (HLW) disposal facility developed by Andra (2005) in France involves emplacing metallic materials (containers, overpacks, liner) into a geological argillaceous formation. During the operational phase, ventilation of handling drifts will keep oxidising conditions at the front of disposal tunnels. Therefore, an oxidising transient may take place in parts of these tunnels in the post-closure phase possibly over several years. During this transient period, the environment of the disposal cell will evolve towards reducing and saturated conditions close to the equilibrium state of the original underground argillaceous formation. Moreover, high temperature conditions above 50 deg. C may be encountered in this environment over a few hundred years. Uniform corrosion represents the main type of degradation of metallic materials for the long term. The oxidising transient will be characterised by high corrosion rates (e.g. localised corrosion) due to the presence of oxygen whereas during the following anoxic stage, the main alteration factor will originate from the pore water associated with lower corrosion rates. In any case, metallic materials corrosion will lead to the release of aqueous iron, which may induce alteration of the favourable confining properties of the clayey materials. In this context, reactive pathways related to the metal corrosion under oxidising conditions and then followed by reducing conditions remain to be further understood (evolution of pH, redox and influence of temperature). Furthermore, some other significant issues remain open, in particular the dissolution/precipitation processes, the argillite perturbation extent and the effects of these transformations on the confining properties of materials. The presence of micro-organisms in deep argillaceous environment and the introduction of new bacterial species in the repository during the operational phase raise the question of their survival under real

  4. Micro-macro modeling of time-dependent behavior of argillite with effects of clay matrix porosity

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. This work is devoted to a micro-macro modeling of time-dependent behavior of argillite considered as possible geological barrier. The Callovo-Oxfordian argillite (Cox argillite) is mainly composed of quartz, calcite and clay minerals and a small quantity of dolomite, feldspar and pyrite. The main grains (quartz and calcite) are in micron scale and the majority of porosity is due to inter-aggregates pores, from sub-micron to nanometer, which are preferentially associated with the arrangement of clay particles. According to this mineralogical analysis, a two-scale micro-macro modeling should be considered: at a mesoscopic scale, the argillite is composed of a continuous porous clay matrix which is embedded by mineral inclusions; at a smaller scale, the clay matrix is itself constituted of a solid phase which is an assembly of clay particles and pores between such particles. In the present paper, a two scale micro-macro model is proposed in the framework of nonlinear homogenization methods. The present work extends the two scale micro-macro modeling of instantaneous elastoplastic behavior of argillites, recently performed by Shen and al. (2012), to time dependent behavior. Therefore, the argillite is considered as a two phase composite with the porous clay matrix and mineral inclusions. The effective properties of the porous clay matrix are described by an elastic-viscoplastic model while the inclusions are considered as linear elastic media. The loading function of viscoplastic flow for the clay matrix is issued from a first homogenization step considering a plastically compressible solid phase described by a Drucker-Prager type criterion taking into account the influence of confining pressure. Further, the loading function depends explicitly on the porosity of clay matrix. For the determination of macroscopic time-dependent behavior of the argillite, a modified Hill's incremental method is used. In the context of

  5. Contribution to the study of mechanical and thermo-hydro-mechanical behaviour of Callovo-Oxfordian argillites. Application to radioactive waste storage

    International Nuclear Information System (INIS)

    This Habilitation thesis presents a synthesis of the different mechanical and thermo-hydro-mechanical coupled aspects of rocks and in particular it deals with a)the phenomena and processes coupled with mechanics in a storage (ch 1); b)the behavior of argillites under thermal, mechanical and coupled hydro-mechanical and thermo-hydro-mechanical solicitations (ch 2 to 4); c)the rheological models and the argillites behavior simulations (ch 5). (O.M.)

  6. Modelling the effective diffusion coefficient of anions in Callovo-Oxfordian argillite knowing the microstructure of the rock

    International Nuclear Information System (INIS)

    After having presented the issue of radioactive waste storage, the concept of geological storage and its application in the Meuse/Haute-Marne underground laboratory, and described the Callovo-Oxfordian geological formation and the argillite transport properties, this research thesis aims at developing a prediction of these properties at a macroscopic scale for water and anions. A first part presents the different experimental means implemented to acquire the diffusion coefficients for the studied materials (Callovo-Oxfordian argillite and purified Puy illite), and the spatial organisation of minerals by LIBS probe-based mapping to highlight a relationship between rock microstructure and its transport macroscopic properties. The next part presents the models which have been developed at the nanometer and micrometre scale to predict the diffusion coefficients. Experimental results are then compared with computed values

  7. Equilibrium partial pressure of CO2 in Callovian-Oxfordian argillite as a function of relative humidity: Experiments and modelling

    Science.gov (United States)

    Lassin, Arnault; Marty, Nicolas C. M.; Gailhanou, Hélène; Henry, Benoît; Trémosa, Joachim; Lerouge, Catherine; Madé, Benoît; Altmann, Scott; Gaucher, Eric C.

    2016-08-01

    Having previously demonstrated that the mineral assemblage of claystone can impose its pCO2 under saturated conditions, we here study the effect of rock desaturation, i.e. the evaporation of pore water, on the partial pressure of CO2 (pCO2) in Callovian-Oxfordian argillite from the Paris Basin (France). In this new study, which combines experiments at room temperature and geochemical modelling, we examine the primary role of capillary forces on chemical equilibria for relative humidity values ranging between 50% and 100%. In particular we are able, without any fitting parameters, to model the experimental decrease of pCO2 as a function of decreasing water content in the argillite. This application to a complex natural system not only confirms the theoretical concepts of geochemistry in capillary contexts, but is promising with respect to other systems, both natural (soil, rock) and industrial (ceramics, granular material).

  8. Sorption--desorption studies on argillite. I. Initial studies of strontium, technetium, cesium, barium, cerium, and europium

    International Nuclear Information System (INIS)

    Distribution ratios were determined for sorption--desorption of radioactive tracers between Eleana argillite available from the Nevada Test Site and a water prepared to be representative of the natural groundwater composition. The measurements were preformed at 220C and 700C under atmospheric oxygen conditions. The order of increasing distribution coefficient by element at both temperatures is Tc(VII), Sr, Cs, Ba, Eu, and Ce. The effects of surface area and mineralogy were also investigated. 34 figures, 26 tables

  9. Detrital zircon geochronology of the Adams Argillite and Nation River Formation, east-central Alaska, U.S.A

    Science.gov (United States)

    Gehrels, G.E.; Johnsson, M.J.; Howell, D.G.

    1999-01-01

    The Cambrian Adams Argillite and the Devonian Nation River Formation are two sandstone-bearing units within a remarkably complete Paleozoic stratigraphic section in east-central Alaska. These strata, now foreshortened and fault-bounded, were originally contiguous with miogeoclinal strata to the east that formed as a passive-margin sequence along the northwestern margin of the North American continent. Seventy-five detrital zircon grains from the Adams Argillite and the Nation River Formation were analyzed in an effort to provide constraints on the original sources of the grains, and to generate a detrital zircon reference for miogeoclinal strata in the northern Cordillera. Thirty-five single zircon grains from a quartzite in the Adams Argillite yield dominant age clusters of 1047-1094 (n = 6), 1801-1868 (n = 10), and 2564-2687 (n = 5) Ma. Forty zircons extracted from a sandstone in the Nation River Formation yield clusters primarily of 424-434 (n = 6), 1815-1838 (n = 6), 1874-1921 (n = 7), and 2653-2771 (n = 4) Ma. The Early Proterozoic and Archean grains in both units probably originated in basement rocks in a broad region of the Canadian Shield. In contrast, the original igneous sources for mid-Protcrozoic grains in the Adams Argillite and ??? 430 Ma grains in the Nation River Formation are more difficult to identify. Possible original sources for the mid-Proterozoic grains include: (1) the Grenville Province of eastern Laurentia, (2) the Pearya terrane along the Arctic margin, and (3) mid-Proterozoic igneous rocks that may have been widespread along or outboard of the Cordilleran margin. The ??? 430 Ma grains may have originated in: (1) arc-type sources along the Cordilleran margin, (2) the Caledonian orogen, or (3) a landmass, such as Pearya, Siberia, or crustal fragments now in northern Asia, that resided outboard of the Innuitian orogen during mid-Paleozoic time. Copyright ?? 1999, SEPM (Society for Sedimentary Geology).

  10. Radiation sensitivity of natural organic matter: Clay mineral association effects in the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    Clay-rich low-organic carbon formations (e.g., Callovo-Oxfordian argillite in France and Opalinus Clay in Switzerland) are considered as host rocks for radioactive waste disposal. The clay-organic carbon has a strong impact on the chemical stability of the clays. For this reason, the nature of the clay-organic carbon, the release of hydrophilic organic compounds, namely, humic (HA) and fulvic acids (FA) and the radiation sensitivity of the undisturbed host rock organics was investigated. The clay sample originates from Oxfordian argillite (447 m depth, borehole EST 104). HA and FA were extracted following the standard International Humic Substance Society (IHSS) isolation procedure. Synchrotron based (C-, K-, Ca-, O- and Fe-edge XANES) scanning transmission X-ray microscopy (STXM) and FT-IR microspectroscopy was used to identify under high spatial resolution the distribution of clay-organic matter with different functionality using principal component and cluster analysis. The results show that in this old (Jurassic) geological formation, small parts of the organic inventory (1-5%) keeps the structure/functionality and can be mobilized as hydrophilic humic substance type material (HA and FA). Target spectra analysis shows best correlation for isolated humic acids with organics found in smectite-rich regions, whereas the extractable FA has better spectral similarities with the illite mixed layer minerals (MLM) regions. After radiation of 1.7 GGy under helium atmosphere the same rock sample area was investigated for radiation damage. Radiation damage in the smectite and illite-MLM associated organic matter is comparably low with 20-30% total oxygen mass loss and 13-18% total carbon mass loss. A critical dose dc of 2.5 GGy and a optical density after infinite radiation (OD∝) of 54% was calculated under room temperature conditions. C(1s) XANES show a clear increase in C=C bonds especially in the illite-MLM associated organics. This results suggests a combination of

  11. Experimental investigation of the interaction of Tournemire argillite with simplified concrete fluids

    International Nuclear Information System (INIS)

    Full text of publication follows: Argillaceous rocks and concrete matrix are considered as potential host rocks and barrier respectively for radioactive waste repositories. The concrete matrix could react with the groundwater of the geological site, inducing a drastic change in its chemical composition and its pH. Consequently, the physico-chemical properties of the rock in contact with this hyper alkaline fluid may be modified [1] which in turn may induce modification of the radioelements behaviour. Therefore, an experimental program has been developed in order to point out the modifications of a clay-stone in contact with alkaline fluids: batch experiments as a preliminary step then diffusion and percolation experiments in order to observe phenomena in repository conditions. Argillite used for these experiments comes from Tournemire and is composed of about 40% of clay minerals (chlorite, illite-smectite mixed layers, illite and kaolinite), quartz (∼25%), feldspars (∼5%), micas (∼5%), calcite (∼10%), dolomite, pyrite (∼3%), and siderite. Series of batch experiments are performed to study the influence of alkaline fluids composition on the argillite degradation. Three different alkaline solutions are used: fluids resulting from contact with fresh concrete (N1), with a moderately degraded concrete (N2) or with a strongly degraded concrete (N3) [2]. Experiments are carried out on powdered and compact solids. The influence of contact time (3 or 6 months) is also tested. Solids are characterized, before and after contact with simplified concrete fluids, by XRD, chemical analysis and SEM whereas pH, cations, anions and carbon contents are measured in each recovered solutions. Interpretations are resulting of both solid and solution analyses. An effect of the concrete degradation level and the contact time is observed on the silicates, sulfurs, carbonates and organic phase for all powdered samples. The microscopic observations of compact samples reveal the

  12. Middle Jurassic Radiolaria from a siliceous argillite block in a structural melange zone near Viqueque, Timor Leste: Paleogeographic implications

    Science.gov (United States)

    Haig, David W.; Bandini, Alexandre Nicolas

    2013-10-01

    Thin-bedded siliceous argillite forming a large block within a structural melange zone at Viqueque, Timor Leste, has yielded a Middle Jurassic (late Bathonian-early Callovian) radiolarian assemblage belonging to Unitary Association Zone 7. Fifty-five species are recognized and illustrated, forming the most diverse radiolarian fauna yet documented from the Jurassic of Timor. The fauna shows little similarity in species content to the few other assemblages previously listed from the Middle or Late Jurassic of Timor, and also has few species in common with faunas known elsewhere in the region from Rotti, Sumatra, South Kalimantan, and Sula. Based on lithofacies similarities and age, the siliceous argillite succession in the melange block at Viqueque is included in the Noni Group originally described as the lower part of the Palelo Series in West Timor. In terms of lithofacies, the Noni Group is distinct from other stratigraphic units known in Timor. It may be associated with volcanic rocks but age relationships are uncertain, although some of the radiolarian cherts in the Noni Group in West Timor have been reported to include tuffaceous sediment. The deep-water character of the siliceous hemipelagite-pelagite facies, the probable volcanic association, and an age close to that of continental breakup in the region suggest deposition in a newly rifted Indian Ocean. In Timor's tectonostratigraphic classification scheme, the Noni Group is here placed in the "Indian Ocean Megasequence".

  13. Definition of an equilibration protocol for batch experiments on Callovo-Oxfordian argillite

    Science.gov (United States)

    Descostes, M.; Tevissen, E.

    In order to elude difficulties concerning reproducing controlled conditions and avoiding chemical perturbation from sampling to laboratory experiments, an equilibration protocol of crushed Callovo-Oxfordian argillite in contact with synthetic pore water is proposed. It consists of a rinse-cycle with chosen synthetic waters. Hence, artifacts such as porosity variability, secondary paragenesis of evaporitic feature and a consecutive changing of water chemistry may be corrected. Equilibrium conditions are defined when both rinsing and leaching solutions are identical. In the first phase of this work, an input grid concerning reaction duration, number of rinsing and water/rock ratio associated to a specify methodology (anoxic and P CO 2 controlled atmosphere glove box) are given. We propose a water/rock ratio equal to 5, a first 72 h rinse followed by three others of 24 h. The protocol was tested among nine synthetic waters and validated regarding major aqueous elements. A geochemical modelling allowed us to identify the reactional mechanisms occurring during the whole procedure in terms of (1) modelling reactions taking place during the various rinses; (2) quantification of the dissolution/precipitation reactions and (3) modelling the condition of the sample. According to the rinsing water composition and P CO 2, dissolution of carbonate minerals may occur and is accompanied by a redistribution of sorbed species at argillaceous mineral surface. Solution analysis coupled with geochemical modelling show an increasing of aqueous K +, consequent upon cationic exchange reactions K +/Na +. Besides, the dissolution of carbonate minerals produced Ca 2+ and Mg 2+ which in turn are exchanged with K + and H +. Silica is controlled by the solubility of chalcedony. However, pH seems to be hardly imposed from the rinsing solution, since it is principally buffered by calco-magnesio-carbonate system. Moreover, anoxic conditions are not sufficient to restore natural reducing

  14. ARGAZ: a new device for experimental study of the coupling between hydrogen production and hydrogen transfer through saturated Callovian-Oxfordian argillite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. A specific experimental device has been designed to produce hydrogen at the metal-argillite interface by electrochemistry. The target is for one hand to reproduce the production of hydrogen occurring when a metal is corroded by the water contained in the porosity of the mud-stone. On the other hand, the transfer of the hydrogen through the mud-stone can be studied. The specific features of the experiment are the following: - Hydrogen is generated inside a cell by electrochemistry, at the interface between the argillite and a metallic surface; no gas injection is required; - Electrochemistry gives the possibility to control the hydrogen production rate; - Hydrogen generation implies water consumption: the water comes from the porosity of the bulk argillite, near the interface; - That one-dimensional experiment has been built around a cylindrical sample of bulk and undamaged argillite coming from the Callovian-Oxfordian formation. Inside the device a cylindrical sample of argillite is placed above a nickel plate. Around the argillite, a ring of compacted bentonite ensures a mechanical confinement. When saturated, the bentonite will apply a swelling pressure close to the total pressure encountered by the sample in the geological formation. The hydrogen is generated at the interface nickel-argillite. The nickel plate is one of the two electrodes required for electrochemistry. At the top face of bentonite, iron electrode is used to close the electrical circuit. The hydrogen produced at the bottom face of the mud-stone is expected to go across the argillite towards the top face. A porous plate connected with a sampling bottle allows the capture of hydrogen. The argillite sample has a diameter of 50 mm, and a height of 50 mm. It is obtained by over-coring a core sample, and by a careful machining leading to a perfect geometry and surface quality. The production rate of hydrogen can be calculated from the current intensity

  15. Sealing efficiency of an argillite-bentonite plug subjected to gas pressure, in the context of deep underground nuclear waste storage

    International Nuclear Information System (INIS)

    In France, the deep underground nuclear waste repository consists of a natural barrier (in an argillaceous rock named argillite), associated to artificial barriers, including plugs of swelling clay (bentonite)-sand for tunnel sealing purposes. The main objective of this thesis is to assess the sealing efficiency of the bentonite-sand plug in contact with argillite, in presence of both water and gas pressures. To assess the sealing ability of partially water-saturated bentonite/sand plugs, their gas permeability is measured under varying confining pressure (up to 12 MPa). It is observed that tightness to gas is achieved under confinement greater than 9 MPa for saturation levels of at least 86-91%. We than assess the sealing efficiency of the bentonite-sand plug placed in a tube of argillite or of Plexiglas-aluminium (with a smooth or a rough interface). The presence of pressurized gas affects the effective swelling pressure at values Pgas from 4 MPa. Continuous gas breakthrough of fully water-saturated bentonite-sand plugs is obtained for gas pressures on the order of full swelling pressure (7-8 MPa), whenever the plug is applied along a smooth interface. Whenever a rough interface is used in contact with the bentonite-sand plug, a gas pressure significantly greater than its swelling pressure is needed for gas to pass continuously. Gas breakthrough tests show that the interface between plug/argillite or the argillite itself are two preferential pathways for gas migration, when the assembly is fully saturated. (author)

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

    International Nuclear Information System (INIS)

    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)

  17. Experimental study on poro-mechanical behavior of saturated Meuse-Haute/Marne argillite subjected to triaxial compression

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Due to its low permeability (10-18 to 10-20 m2), the Meuse-Haute/Marne argillite is chosen as the candidate host rock for the geological disposal of high-level radioactive waste by 'Agence Nationale de gestion des Dechets Radioactifs' (ANDRA). During the excavation of the underground tunnel in argillite formation, the Excavation Damaged Zone (EDZ) is expected to develop due to the stress redistribution during excavation and subsequent rock convergence. The nucleation and propagation of microcracks in EDZ can consequently affect the poro-mechanical behavior of the host rock. Therefore, it is of crucial importance to study the poro-mechanical behavior of Meuse-Haute/Marne argillite under the influence of stress induced microcracks. For this purpose, this paper presents the original experimental results of drained and undrained triaxial compression tests as well as evolution of Biot's coefficient during hydrostatic and deviatoric loading of saturated Meuse-Haute/Marne argillite. The size of samples used in the present work is 20x20 mm in order to reduce the saturating time. The axis of the cylindrical sample is perpendicular to the bedding planes. The test system is placed in an insulated room and a temperature control system is used to maintain a constant temperature of 20 ±0.2 C. The saturation condition is an important factor for the determination of the mechanical and poro-elastic properties of saturated argillite. Thus, for each sample, after putting into the triaxial cell, the confining pressure is loaded to 2 MPa and we inject distilled water both at the injection and outlet faces in order to insure the pore pressure at the two faces hold at 1 MPa. This procedure will be keep to 72 hours. Then, the pore pressure at the injection face is increased to 1.5 MPa, and we record the pore pressure at the outlet face. Once the pore pressure at the outlet face reaches the same value at injection face, the sample is

  18. Sr, C and O isotopes as markers of alkaline disturbances in the Toarcian argillites of the Tournemire experimental platform (France). Case of a 15-years old engineered analogue.

    Science.gov (United States)

    Techer, I.; Boulvais, P.; Bartier, D.; Tinseau, E.

    2009-04-01

    In France, the concept of a geological disposal of high-activity and long-period nuclear wastes requires the use of concrete and cement-bearing materials as building structures or as waste containment packages, in conjunction with clayey barriers (e.g., compacted bentonite as an engineered barrier and/or argillite-type rocks as a geological barrier). Hydrolysis of cementitious phases is however known to produce hyper-alkaline pore fluids with pH ranging from 10 to 13.5 that will be in disequilibrium with the geological setting environment (argillite pore-water pH around 8). The disturbance of clayey rocks in contact with such materials is thus an important task in safety assessment studies of deep geological storage. This concerns the knowledge of mineral / solution paths but also the spatial extent of the alkaline plume into the clayey material. Experimental and modelling approaches were performed this last decade to answer these questions. In addition to these approaches, natural or engineered contexts in which a clayey formation has been in contact with cementitious materials can be considered as analogues of a deep geological storage for the study of argillite /cement interaction. Such contexts can be found in the IRSN Tournemire experimental platform in Aveyron (France). This platform is based on a tunnel, excavated between 1882 and 1886 through Domerian marls and Toarcian argillites, which is dedicated since 1990 to multidisciplinary research programs. In the frameworks of these programs, exploration boreholes were realized from the basement of the tunnel in the 1990 years. The boreholes were then filled with concrete and cement that are presently in contact with the Toarcian argillites for 15-20 years. One of this borehole - DM borehole - was overcored in 2005 in order to collect the Toarcian argillites in contact with the cement and the concrete. Mineralogical, petrographic and microstructural analyses have argued for a clear disturbance of the Toarcian

  19. Impact of iron-reducing bacteria on the properties of argillites in the context of radioactive waste geological disposal

    International Nuclear Information System (INIS)

    The presence of indigenous microorganisms in deep clayey geological formations raises the issue, regarding radioactive waste geological disposal, of the influence of bacterial activity on the confinement properties of materials, including the clayey host rock. Iron-reducing bacteria (IRB) activity is assessed in batch experiments in the presence of argillite samples from an in situ experimental laboratory at Tournemire (Aveyron, France). The results show the availability of structural Fe(III) from the clay minerals for biochemical reactions (bioreduction). In laboratory conditions, a significant impact of IRB on the alteration of clay minerals, mainly the illite-smectite mixed layer (I-Sm), is indeed observed. Such reactions may locally modify the physicochemical conditions and the stability of clay minerals (essentially smectites) prevailing in such deep facilities. More generally, bacterial activity could play an important role on clay mineral alteration and in situ experiments need to be performed in order to quantify the reaction rates and show the representative of these phenomena in the framework of the safety assessment of waste disposal. (authors)

  20. Determination of hydraulic properties of the Callovo-Oxfordian argillite at the bure site: Synthesis of the results obtained in deep boreholes using several in situ investigation techniques

    Science.gov (United States)

    Distinguin, Marc; Lavanchy, Jean-Marc

    Since 1991, ANDRA ( Agence Nationale pour la gestion des Déchets Radioactifs - National Radioactive Waste Management Agency) has been performing research on the possibility of geologic disposal of high level radioactive waste. In 1999, Andra began constructing an Underground Research Laboratory at Bure, a site located on the border of the Meuse-Haute-Marne departments, 300 km East of Paris. The laboratory is investigating the Callovo-Oxfordian argillite, a 130 m thick middle Jurassic stratum, at a depth of about 420 m. Argillite is a clay-rich sedimentary rock with low-permeability. Between 1994 and 2004, Andra collected from deep boreholes an impressive wealth of data covering a wide range of geosciences. This paper focuses on the hydraulic data related to argillite, including the results from short-term hydraulic packer tests and long-term monitoring of the formation pressures. Three types of tools are used on the site for investigations in deep boreholes. The first one is a conventional packer test tool used in the petroleum industry and adapted for hydrogeological purposes. The main objective is to determinate the permeability of the formation through short-term tests (24-72 h) at about 10 regular intervals. The two other types of tool are permanent monitoring devices. The electromagnetic pressure gauge (EPG) is totally isolated from the surface perturbations. There are no electric or hydraulic lines to the surface and the borehole is cemented. The advantage of this tool is that the formation almost recovers its initial pressure, avoiding disturbances from surface. Although the multi-packer equipment, installed in an open borehole can be affected by surface perturbations, it is used to measure pressure at different isolated levels in the same borehole ( i. e., 11 chambers in one borehole). Evaluations of the formation pressure (freshwater head) and hydraulic conductivity have been performed for all intervals investigated (19 short-term packer tests and 15 long

  1. Confinement properties evolution of the cap-rocks argillite-type under CO2 enriched-fluids: impact of the natural and artificial discontinuities

    International Nuclear Information System (INIS)

    This research is part of the studies of feasibility of CO2 storage in deep geological strata, focusing more particularly on the evolution of the confinement properties of cap-rocks type argillite subjected to CO2 enriched fluids. The argillite of Tournemire (Aveyron, France) were used as analog rocks, having identified what their weak points could be face to storage, namely their mineralogy, natural fractures filled with calcite and the presence of interfaces cement/argillite expected in filled injection wells. The 'through diffusion' experimental setup has been adapted to estimate (i) the possible modification of diffusive transport parameters recorded before and after acid attack for different radioactive tracers (tritium and chlorine-36) and non-radioactive tracers (deuterium and bromide) used to characterize samples of argillite of Tournemire and cement paste and (ii) the evolution of the chemical compositions of the solutions in the upstream and downstream reservoirs of diffusion cells during acid attacks. Finally, the analysis of solids was carried out in part by SEM-EDS, XRD and X-μTomography. Firstly, for all the samples studied, the values of the transport parameters determined before acid attack (effective diffusion coefficient and porosity) are consistent with those of the literature. In addition, it appears that all materials have reacted strongly to acid attacks. Thus, argillites saw their diffusion parameters increase up to a factor of two, especially for anionic tracers, and, whatever the proportion of carbonate minerals initially present in samples of argillite. The post-mortem observations have led to the identification of a zone of dissolution of carbonate minerals in them, but whose extension (400 microns or less) can not alone explain the significant degradation of the containment properties. Only unobservable phenomena during investigation scale, such as wormhole effects in porous network could be the cause. In addition, the samples of

  2. What can we learn from existing in situ cement based materials/Callovo-Oxfordian argillite interface sampled in the ANDRA underground research laboratory?

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Within the French concepts, concrete will be used to build access structures, galleries as well as vaults and waste packages for Intermediate Level Wastes (ILW). The assemblage of natural (host rock) and engineered barriers (bentonite and cement materials) used in storage cells (eg. plugs for sealing, support materials for the access gallery), provides numerous interfaces with contrasting geochemical conditions. The main goals of this study are linked to the knowledge of the chemical and physical evolution with time at the clay/cement based materials interface, in order to assess: (1) the kinetic and the extension of the degradation of the Callovo-Oxfordian argillite under the influence of alkaline plume. These interactions could modify the mineralogy and the transport properties of the rock (eg. porosity clogging induced by secondary minerals formation); (2) the concrete chemical degradation under the influence of the clay pore water. (concrete carbonation, hydrolysis with physical consequences especially with regards to transfer properties). To tackle this issue, two existing contacts between Callovo-Oxfordian argillite and cement based materials were sampled in the ANDRA (French Radioactive Waste Management Agency) Underground Research Laboratory (Meuse/Haute Marne, France) in order to describe in situ alkaline degradations in terms of mineralogy, chemistry, physical and textural parameters. (1) The first contact (A) concerns short-crested concrete in the access gallery. These samples which experienced 4 to 5 years of contact were drilled from the wall of the gallery. They offer the opportunity to describe on both sides (i) the alteration of the concrete link to the ventilation of the access gallery (atmosphere/concrete interface) and (ii) the concrete/clay interfaces. (2) The second one (B) deals with a bore hole fulfilled with a cement which also experienced 4 to 5 years of contact with the argillaceous media

  3. Micro-mechanics based modeling of the Callovo-Oxfordian argillite mechanical behavior; Modelisation micro-macro du comportement elastoplastique endommageable de l'argilite du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Chakra Guery, A.; Cormery, F.; Shao, J.F.; Kondo, D. [Laboratory of Mechanics of Lille, UMR 8107, 59 - Villeneuve d' Ascq (France); Abou-Chakra Guery, A. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2007-05-15

    The present study is devoted to the development and validation of a non-linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as an heterogeneous one composed of an elastoplastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the Hill-type incremental method [1]. The approach consists in formulating the macroscopic tangent operator of the material from the non-linear local behavior of its phases. Due to the matrix/inclusion morphology of the microstructure of the argillites, a Mori-Tanaka scheme is considered for the localization step. The developed model is first compared to Finite-Elements calculations and then validated and applied for the prediction of the macroscopic stress-strain responses of argillites. (authors)

  4. Temporal and spatial variability of Fe and Mn in perched groundwater flowing through weathered argillite underlying a steep forested hillslope

    Science.gov (United States)

    Kim, H.; Bishop, J. K.

    2013-12-01

    Groundwater flowing through weathered bedrock dictates the runoff chemistry to streams in many catchments yet; its chemical evolution has been rarely documented. In particular, observations of Fe and Mn dynamics in groundwater are extremely challenging due to their high reactivity. To preserve the sample integrity for these elements we have developed a new sampling scheme that is applicable to autosamplers; a gravitational filtration system (GFS). GFS is capable of filtering samples by gravity within 30 minutes after the sampling. The GFS samples showed a good agreement with reference samples, which were collected following the standard sampling method for trace metals (i.e. immediate filtration and acidification). Since October 2011, GFS has been employed to monitor Fe and Mn in perched groundwater that moves through weathered argillite in an intensively instrumented hillslope (Rivendell), in the Angelo Coast Range Reserve. The study site is located at the headwaters of the Eel River, northern California, characterized by a typical coastal Californian Mediterranean climate. We collected groundwater samples at 3 wells along the hillslope (upslope (W10), mid-slope (W3) and near the creek (W1)) with 1-3 day intervals. Additionally, rainwater and throughfall samples were collected at a meadow near the hillslope and at the middle of the hillslope, respectively. The results from our observations indicate that Fe and Mn exhibit distinct spatial and temporal behavior under variable hydrologic conditions. The concentrations of Fe in throughfall vs. rainwater were similar (0.45μM vs. 0.49μM), but Mn in throughfall was 10-fold higher than that in rainwater (1.2 μM vs. 0.1 μM). In the early rainy season, W10's water table was deep (-18m) and Fe and Mn in W10 were 30-150 nM and 1-2 μM, respectively. As the rainy season proceeds, W10's water table rose by 4-6m, indicating the arrival of new water. At this time, Mn in W10 decreased to ~0.1 μM, synchronizing with the water

  5. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    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)

  6. Contributions to micromechanical model of the non linear behavior of the Callovo-Oxfordian argillite; Contributions a la modelisation micromecanique du comportement non lineaire de l'argilite du callovo-oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Chakra Guery, A

    2007-12-15

    This work is performed in the general context of the project of underground disposal of radioactive waste, undertaken by the French National Radioactive Waste Management Agency (ANDRA). Due to its strong density and weak permeability, the formation of Callovo-Oxfordian argillite is chosen as one of possible geological barriers to radionuclides. The objective of the study to develop and validate a non linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as a composite constituted of an elasto(visco)plastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the incremental method proposed by Hill. The derived model is first compared to Finite Element calculations on unit cell. It is then validated and applied for the prediction of the macroscopic stress-strain responses of the argillite at different geological depths. Finally, the micromechanical model is implemented in a commercial finite element code (Abaqus) for the simulation of a vertical shaft of the underground laboratory. This allows predicting the distribution of damage state and plastic strains and characterizing the excavation damage zone (EDZ). (author)

  7. Microbial activity in argillite waste storage cells for the deep geological disposal of French bituminous medium activity long lived nuclear waste: Impact on redox reaction kinetics and potential

    Science.gov (United States)

    Albrecht, A.; Leone, L.; Charlet, L.

    2009-04-01

    Micro-organisms are ubiquitous and display remarkable capabilities to adapt and survive in the most extreme environmental conditions. It has been recognized that microorganisms can survive in nuclear waste disposal facilities if the required major (P, N, K) and trace elements, a carbon and energy source as well as water are present. The space constraint is of particular interest as it has been shown that bacteria do not prosper in compacted clay. An evaluation of the different types of French medium and high level waste, in a clay-rich host rock storage environment at a depth between 500 and 600 m, has shown that the bituminous waste is the most likely candidate to accommodate significant microbial activity. The waste consists of a mixture of bitumen (source of bio-available organic matter and H2 as a consequence of its degradation and radiolysis) and nitrates and sulphates kept in a stainless steel container. The assumption, that microbes only have an impact on reaction kinetics needs to be reassessed in the case where nitrates and sulphates are present since both are known not to react at low temperatures without bacterial catalysis. The additional impact of both oxy-anions and their reduced species on redox conditions, radionuclide speciation and mobility gives this evaluation their particular relevance. Storage architecture proposes four primary waste containers positioned into armoured cement over packs and placed with others into the waste storage cell itself composed of a cement mantle enforcing the argillite host rock, the latter being characterized by an excavation damaged zone constricted both in space and in time and a pristine part of 60 m thickness. Bacterial activity within the waste and within the pristine argillite is disregarded because of the low water activity (low mobility of critical RN, • increased retardation of mobile RN in biofilms (i.e. adsorption on microbial cell surfaces and products of possible biomineralization); complexation by

  8. Tracing interactions between natural argillites and hyper-alkaline fluids from engineered cement paste and concrete: Chemical and isotopic monitoring of a 15-years old deep-disposal analogue

    International Nuclear Information System (INIS)

    Samples of Toarcian argillite were collected both next to and far from a CEM II cement paste and a CEM II concrete, within the specific context of a 15-a old borehole located in the Tournemire Experimental Platform (Aveyron, France). The objectives were evaluation of the mineralogical and geochemical changes of the claystone at the contact with the cementitious materials and determination of the spatial extent of the interactions. The approach includes the examination of the mineralogical (XRD, SEM, TEM), chemical (major, trace, rare earth elements) and isotopic (Sr, C, O) compositions of argillite whole-rocks and of various soluble phases, at two scales: in the rock matrix (P1 scale) and along micro-cracks (P2 scale). The two study scales outline nearly similar mineralogical modifications, shown by the presence of Ca silicate hydrates (C–S–H) and newly-formed CaCO3 within 10–15 mm of the cement paste and concrete. Chemical data from whole-rock argillites indicate few changes in a slightly thicker zone (18–20 mm), mainly consisting of an increase in the CaO wt.%, and a decrease in Sr contents. The other elementary contents remained quite constant except for MgO, which suggests redistribution with precipitation of a Mg-rich mineral phase at 20 mm from cement paste/concrete interface. Acetic acid leachates had more pronounced variations, including a decrease of the total elementary content in the same ‘geochemical disturbed zone’ (GDZ), together with a significant increase of the Sr isotopic ratios. A combination of Sr and C/O isotopic patterns was used to distinguish the behavior of secondary cementitious phases in the clay-rich rock: (i) calcite dissolution and re-precipitation is supported by C/O isotopic data and (ii) C–S–H neoformation is evidenced by the 87Sr/86Sr ratios; this tool also contributes to determine the origin of the fluids. The proportion of newly-formed C–S–H in the matrix and in the micro-cracks of the argillite is modeled.

  9. Biogeochemical reactive-transport modelling of the interactions of medium activity long-lived nuclear waste in fractured argillite and the effect on redox conditions

    International Nuclear Information System (INIS)

    model also examines the reaction of nitrate with Fe(II) minerals present in the COx, which have the potential to reduce nitrate. This results in the oxidation of Fe(II) and the intermediate formation of Fe(III) minerals, which provide electron acceptors which are subsequently reduced by organics. The model has examined the case where the nitrate affected system returns to a reduced state resulting from continued input of acetate. In this scenario sulphate reduction develops in the COx, By considering the concentration of electron donors and acceptors for the major redox couples the GRM calculates a redox potential. Further results will be presented, of the spatial and temporal distributions in reactive species, minerals and microbial biomass related to the coupling of microbial kinetics, under the influence of advective and diffusive transport. The results will be discussed and interpreted to assess the potential significance of environmental factors that may control microbial growth and the mediation of redox conditions in argillite host rocks. (authors)

  10. Determination of hydraulic properties of the Callovo-Oxfordian argillite at the Bure site: synthesis of the results obtained in deep boreholes using several in-situ investigation techniques

    International Nuclear Information System (INIS)

    Over the last years, Andra has collected an impressive amount of hydraulic data on the middle Jurassic, Callovo-Oxfordian argillite at a site located 300 km eastern from Paris. Preliminary analyses of the formation pressure (freshwater potential) and the hydraulic conductivity have been performed based on the hydraulic data of both the short term packer tests and the long term monitoring (EPG and Westbay). This was performed using numerical borehole simulators which enable taking into account the complete pressure history of the borehole, defining a suitable flow model and deriving best guess estimates and uncertainty ranges of the hydraulic parameters. For all measurement intervals investigated In-Situ, it was shown that the hydraulic conductivity was less than 2,10-12 m/s. A comparison of the preliminary results of the packer tests and those of the long term pressure monitoring shows that the short term packer tests tend to highly over-estimate the formation pressure. The hydraulic conductivities obtained from the analysis of the packer tests are mostly higher than those obtained from the analysis of the EPG long term recovery. Further analyses are planned to check these preliminary analyses as well as the consistency between short term and long term measurements providing information on rock properties at different scales (different radius of visibility). (authors)

  11. Multi-phenomena couplings in argillites

    International Nuclear Information System (INIS)

    (author) The objective of this research thesis is to be a contribution to electro-kinetic phenomena at the continuum scale (about the nanometer) in a complex porous structure. After a general overview of equations and problems raised by electro-kinetic phenomena (geological barriers for radioactive wastes, local electrokinetic equations, porous media, parallel computing and numerical simulation), the author addresses the electro-osmosis in porous solids for high zeta potentials (electrokinetic equations and their resolution) and generalizes his approach to universal electro-osmosis formulae for porous media. He reports the study of ionic transports in porous media for high zeta potentials (electrokinetic equations and numerical simulation) and of the influence of the Stern layer on electrokinetic phenomena

  12. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  13. Clay content of argillites: Influence on cement based mortars

    OpenAIRE

    Habert, Guillaume; CHOUPAY, Nathalie; Escadeillas, Gilles; MONTEL, Jean Marc; Guillaume, D

    2009-01-01

    The pozzolanic activity of four heated powders containing different clays has been tested. Mineral transformations during calcination from 20 to 900 °C have been followed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Compressive strength tests were performed at 1, 7 and 28 days on cement-clay mortars using 30% of pozzolanic material as a replacement by mass for cement. Calcination temperatures corresponded to the stages of potentially high reactivity identified by XR...

  14. Diagenesis and transfers in fractured argillaceous environment: the Tournemire argillite (Aveyron, France)

    International Nuclear Information System (INIS)

    The Tournemire experimental site (Aveyron, France) is located on the Western margin of the Causses basin, South of Massif Central, and is studied as natural analogue of a nuclear wastes disposal site by the French Institute for Nuclear Safety and Radioprotection (IRSN). It is situated inside a former railway tunnel passing through a lithified and fractured Toarcian shale formation, 200 m thick, covered by a 300 m thick limestone and dolomite aquifer. This work aims at characterizing the evolution of confinement capacities in the shale during its geological history. In the Causses basin, sedimentary dynamics are uncertain during Lower Cretaceous due to an important Cretaceous erosion event. The thermal history of the region was reconstructed to solve this problem, using geo-thermometers and geo-chrono-thermometers. Organic mater Tmax determined by Rock-Eval pyrolysis range from 433 to 440 deg C and indicate diagenetic condition consistent with oil window upper limit. Homogenization temperatures in two-phase aqueous inclusions measured between 80 and 120 deg. C, the occurrence of ordered mixed layer with illite content higher than 70%, and thermal resetting of apatite fission tracks agree with these conditions. Fission tracks data reveal the occurrence of an important and quick denudation beginning at about 120-110 Main the Causses area, consistent with the Durancian Isthmus formation in the SE basin. Tmax modelling supports the sedimentation of 800 to 1600 m thick deposits during Lower Cretaceous. Those sediments were removed during the erosion period that occurred between 110 and 90 Main the Causses basin. During Jurassic, a global extension phase induces subsidence in the Causses basin, and cause the shale burial. Another deformation phase, a compression phase, occurred during Eocene, owing to the Pyrenean orogeny. During extension, calcite veins crystallized at temperatures between 80 and 120 deg C from fluids evolved from marine water, whereas they crystallized at temperatures between 30 and 40 deg C from a fluid with a strong meteoric component during the compression. Affinities between shale cement and calcite veins in shale suggest carbon in calcite veins is buffered by the shale. In a N130 sinistral fault, the overlying Aaleman limestone contributes to some extent to the carbonate in calcite veins. This suggests the N130 sinistral fault could connect with the upper aquifer during compression. In the Toarcian shale, Fe content in calcite veins suggests calcite crystallized in reduced environment during both extension and compression. In Shale, mineral species do not vary near the N130 sinistral fault, though a slight decrease in Ca, Sr and carbonate concentrations in a metric zone on either side of the main fault plane suggests these elements are mobilized. A δ18O variation in the same zone confirms that the shale cement is partially recrystallized. Barium and zinc are accumulated in baryte and pyrite near the main fault plane. Slight variations in U and Th concentrations were observed but it is difficult to discriminate a sedimentary variation from a diagenetic remobilization. Very low U content in calcite veins indicate U is retained in shale, since shale constitutes a reduced and alkaline environment. A slight enrichment in heavy rare earth elements relatively to light rare earth elements, and the occurrence of a authigenic florencite suggest rare earth elements were mobilized in the metric zone on either side of the main fault plane. Confinement capacities are estimated in the Toarcian shale during the Eocene compression, tacking into account the connection of the N130 sinistral fault and the occurrence of a perturbed metric zone on either sides of this fault. (author)

  15. Pore network connectivity anisotropy in Jurassic argillite specimens from Eastern Paris Basin (France)

    International Nuclear Information System (INIS)

    In order to scientifically test the feasibility of storage of high activity nuclear wastes, ANDRA, the French radioactive waste management agency, gave us the opportunity to study entirely preserved specimens of Jurassic clay-rich rocks from eastern Paris Basin. The collection was realised in the frame of a reconnaissance study that now leads to the building, under progress, of a -400 m-deep Laboratory, close to the village of Bure. The rocks under study consist in dark- to light-grey silty marls, or clay-stones, that were deposited during the Callovian and the beginning of the Oxfordian, called Cox (Callovo-Oxfordian) argilites. According to pyrolysis data of the organic fraction and to fluid inclusion studies, these argilites never reached 50 C in temperature nor have been buried deeper than 800 m, hence retain most of their original physical and chemical properties that were examined through microstructural and SEM observations. (authors)

  16. Analysis of water/gas flows in argillites from Callovo-Oxfordian using gradient percolation

    International Nuclear Information System (INIS)

    The work presented in this manuscript is motivated by the study of nuclear waste underground repository. In this context, we study the hyper slow drainage problem, which is related to the gas production, mainly hydrogen, taking place within the repository. Although the gas production rate is quite small, and thus the drainage hyper slow, the amount of produced gas is quite significant because the production takes place over thousands years. The study is performed within the framework of the theory of invasion percolation in a gradient. We first show that the hyper slow drainage process can be modelled using the traditional two-phase flow model based on the generalized Darcy's law. A crucial step is then to specify properly the parameters of the model. We show how they must be specified from the asymptotic behaviours of the parameters for an infinite medium as predicted by percolation theory. The obtained solution indicates that the hyper slow drainage operates in the vicinity of breakthrough pressure, which is the subject of a specific study. Furthermore, the hyper slow drainage is characterized by a weak desaturation of the medium and a great sensitivity to the model parameters in the range of high wetting fluid saturation. We also study the impact of coupling between the flow and the local deformation of porous matrix at the pore network scale from numerical simulations using a model coupling a pore network model and a deformation model based on a system of interconnected springs. The simulations indicate a major change of the invasion pattern compared to the rigid matrix with the self-generation of invasion preferential paths when the coupling is sufficiently strong. (author)

  17. Field examination of shale and argillite in northern Nye County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, J. R.; Woodward, L. A.; Emanuel, K. M.; Keil, K.

    1981-12-01

    Thirty-two locales underlain by clay-rich strata ranging from Cambrian Pioche Shale to Mississippian Chainman Shale and equivalents were examined in northern Nye County, Nevada. The text of the report summarizes data for each stratigraphic unit examined. Checklists for tabulating field data at each locale are included in an appendix. Working guidelines used to evaluate the locales include a minimum thickness of 150 m (500 ft) of relatively pure clay-rich bedrock, subsurface depth between 150 m (500 ft) and 900 m (3000 ft), low topographic relief, low seismic and tectonic activity, and avoidance of areas with mineral resource production or potential. Field studies indicate that only the Chainman Shale, specifically in the central and northern parts of the Pancake Range, appears to contain sites that meet these guidelines.

  18. Field examination of shale and argillite in northern Nye County, Nevada

    International Nuclear Information System (INIS)

    Thirty-two locales underlain by clay-rich strata ranging from Cambrian Pioche Shale to Mississippian Chainman Shale and equivalents were examined in northern Nye County, Nevada. The text of the report summarizes data for each stratigraphic unit examined. Checklists for tabulating field data at each locale are included in an appendix. Working guidelines used to evaluate the locales include a minimum thickness of 150 m (500 ft) of relatively pure clay-rich bedrock, subsurface depth between 150 m (500 ft) and 900 m (3000 ft), low topographic relief, low seismic and tectonic activity, and avoidance of areas with mineral resource production or potential. Field studies indicate that only the Chainman Shale, specifically in the central and northern parts of the Pancake Range, appears to contain sites that meet these guidelines

  19. Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

    International Nuclear Information System (INIS)

    The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

  20. Characterization and modeling of natural tracers' transfers through the argillites of Tournemire (France)

    International Nuclear Information System (INIS)

    The French Institute for Protection and Nuclear Safety (IPSN) is investigating the argillaceous formation of Tournemire (France) as a methodological underground laboratory for conducting research on the feasibility of deep geological repositories for radioactive waste in argilites. Because of the very low water content and hydraulic conductivity of the argilites, the migration through this media should be very low. The fluid flow regime and transport have been studied using natural tracers from the interstitial water. The deuterium and chloride of interstitial water have been chosen for their conservative behavior. After the development of a protocol for the chloride extraction from the water, and tests on the vacuum distillation method for the water extraction from the rock, systematic data acquisition has been performed on the argillaceous sequence of the massif and near the fracture areas. Both chloride and deuterium profiles suggest that transfers are mainly diffusive at the massif scale. But the profiles show an enrichment in delta D and delta 18O of the interstitial solution in the area of one meter adjacent to a fracture compared to pore water of samples located at further distance. Therefore, these observations are suggesting that a second process could generate specific transfers, at the vicinity of faults. The hypothesis of the molecular diffusion as a dominant process for transport was successfully tested using a transport model, over periods of several tenth of millions years, taking into account geodynamical features of the region (such as tectonic and induced faults), and assuming that some variations of the tracer concentrations at the system boundaries occurred during the major climate-change periods. Even if tracers' transfers are mainly diffusive at the massif scale, they are or should have been affected by a second process causing heterogeneity of concentrations at the vicinity of faults. This process involves either, intrusion of salted solutions or internal transfers due to overpressures. (author)

  1. Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

    Energy Technology Data Exchange (ETDEWEB)

    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, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-07-01

    The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

  2. A heating experiment in the argillites in the Meuse/Haute-Marne underground research laboratory

    International Nuclear Information System (INIS)

    A heating experiment named TER is being conducted with the objectives to identify the thermal properties, as well as to enhance the knowledge on THM processes in the Callovo-Oxfordian clay at the Meuse/Haute Marne Underground Research Laboratory (France). The in situ experiment has being switched on from early 2006. The heater, 3 m length, is designed to inject the power in the undisturbed zone at 6 m from the gallery wall. A heater packer is inflated in a metallic tubing. During the experiment, numerous sensors are emplaced in the surrounding rock and are experienced to monitor the evolution in temperature, pore-water pressure and deformation. The models and numerical codes applied should be validated by comparing the modeling results with the measurements. In parallel, some lab testing have been achieved in order to compare the results given with two different scales (cm up to meter scale). In this paper, we present a general description of the TER experiment with installation of the heater equipment and the surrounding instrumentation. Details of the in situ measurements of temperature, pore-pressure and strain evolutions are given for the several heating and cooling phases. The thermal conductivity and some predominant parameters in THM processes (as linear thermal expansion coefficient and permeability) will be discussed. (authors)

  3. Water Retention Capacity of Argillite from the VE Test - Phase II at Mont Terri: Effect of Ventilation

    International Nuclear Information System (INIS)

    The VE (ventilation) test carried out at the Mont Terri underground laboratory in Switzerland intended to evaluate in situ the behaviour of a consolidated clay formation when subjected to alternate periods of flow of wet and dry air during several months. For that, a 10-m gallery was excavated in the Opalinus Clay formation and carefully instrumented. Before and after a second ventilation phase boreholes were drilled. Samples were taken from the drill cores and were analysed from mineralogical and geochemical points of view. Also, the retention curves of these samples were determined in the laboratory following drying paths performed under free volume conditions at 20 degree centigrade, what is the content of this report. Although there are not large differences in the WRC of samples taken from different boreholes, at different distances from the gallery wall or before or after ventilation, those samples taken near the gallery wall and after ventilation tend to show a higher water retention capacity. This has been correlated to the higher salinity of the pore water of these samples, what increases their osmotic suction. This effect is attenuated towards high suctions. (Author) 10 refs

  4. Magnetic mineralogy of Jurassic argillite specimens from Eastern Paris Basin (France): coexisting iron-sulphides and iron-oxides

    Energy Technology Data Exchange (ETDEWEB)

    Esteban, L.; Bouchez, J.L.; Siqueira, R. [Universite Paul-Sabatier, Lab. des Mecanismes et Transferts en Geologie (LMTG - UMR 5563 CNRS), 31 - Toulouse (France); Esteban, L. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France); Geraud, Y. [Ecole et Observatoire des Sciences de la Terre de Strasbourg (EOST), 67 - Strasbourg (France)

    2005-07-01

    Core-specimens belonging to the top and basal parts of the Callovo-Oxfordian dark-grey clay-rich sediment (Cox) of Eastern Paris Basin that were drilled by Andra (the French radioactive waste management agency), were subjected to a thorough magnetic mineralogy study and SEM observations, in order to characterize the nature and origin of the ferromagnetic fraction. Specimens from the top part of the Cox, best represented by T1-337, have large magnetic variabilities while those from the base, typified by T1-455, have very constant properties. Susceptibility magnitudes that vary from 12 to 94 {mu}SI (T1-337) and from 116 to 133 {mu}SI (T1-455), call for a dominant paramagnetic fraction mainly due to the iron-bearing clay fraction (smectite, illite) that make up to 45% of the rock-volume. The ferromagnetic contributions to susceptibility range from {approx}25% in T1-337 to {approx}12% in T1-455 and result from the addition of two main ferromagnetic fractions, or phases, as evidenced from coercivity spectra obtained after progressive AF-demagnetization of both the natural and the induced remanence. A soft fraction systematically appears in-between 4 and 8 mT, and a hard one in-between 10 and 22 mT. Interestingly, the natural remanence of the soft fraction keeps the memory of the (sub) present magnetic north, allowing core-reorientation, while the hard fraction has a random NRM vector. The soft magnetic fraction is argued to equate with the ubiquitous early diagenetic iron-sulphides, as observed in SEM, and that form various arrangements of framboidal aggregates of micron-size pyrite grains to which greigite is likely associated. Likewise, the hard fraction is equated with the less abundant Ti-Fe-oxide clastic grains, consistent with the random nature of the NRM. Hence, the coexistence in the same sediment of iron-sulphides and iron-oxides, classical environmental markers of redox conditions, is here related to distinct origins rather than to changing conditions during sedimentation or diagenesis. Preservation of these species is attributed to the very low permeability that the sediment reached after its compaction. (authors)

  5. A cross method of a nano-scale modeling and macroscopic data to estimate anion effective diffusion coefficient in argillite

    International Nuclear Information System (INIS)

    Based on a mechanistic understanding of solute migration in pure clay at nano-metric scale, a model has been developed to evaluate the effective diffusion coefficient De in clay-rocks at the centimeter scale from the description of the mineralogy (and its heterogeneity) of the rock at the micrometer scale. Given a DeCHTO in the clay matrix an effective diffusion coefficient can be calculated for the rock taking into account the mineralogical microstructure of the sample. The diffusion properties of the clay matrix govern the diffusion behaviour of chloride. (authors)

  6. A cross method of a nano-scale modeling and macroscopic data to estimate anion effective diffusion coefficient in argillite

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, N.; Goutelard, F. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR/L3MR), 91 - Gif sur Yvette (France); Turq, P. [Universite Pierre et Marie Curie, LI2C, 75 - Paris (France)

    2007-07-01

    Based on a mechanistic understanding of solute migration in pure clay at nano-metric scale, a model has been developed to evaluate the effective diffusion coefficient De in clay-rocks at the centimeter scale from the description of the mineralogy (and its heterogeneity) of the rock at the micrometer scale. Given a De{sub C}{sup HTO} in the clay matrix an effective diffusion coefficient can be calculated for the rock taking into account the mineralogical microstructure of the sample. The diffusion properties of the clay matrix govern the diffusion behaviour of chloride. (authors)

  7. Hydrogen solubility in pore water of partially saturated argillites: Application to Callovo-Oxfordian clay-rock in the context of a nuclear waste geological disposal

    International Nuclear Information System (INIS)

    In nuclear waste geological disposals, large amounts of hydrogen (H2) are expected to be produced by different (bio-)geochemical processes. Depending on the pressure generated by such a process, H2 could be produced as a gas phase and displace the neighbouring pore water. As a consequence, a water-unsaturated zone could be created around the waste and possibly affect the physical and physic-chemical properties of the disposal and the excavation disturbed zone around it. The present study is the first part of an ongoing research program aimed at evaluating the possible chemical evolution of the pore water-minerals-gas system in such a context. The goal of this study was to evaluate, in terms of thermodynamic equilibrium conditions, the geochemical disturbance of the pore water due to variations in hydrogen pressure, temperature and relative humidity. No heterogeneous reactions involving mineral phases of the clay-rock or reactive surface sites were taken into account in the thermodynamic analysis. In the case sulphate reduction reaction is allowed, geochemical modelling results indicate that the main disturbance is the increase in pH (from around 7 up to more than 10) and an important decrease in the redox potential (Eh) related to hydrogen dissolution. This occurs from relatively low H2 partial pressures (∼1 bar and above). Then, temperature and relative humidity (expressed in terms of capillary pressure) further displace the thermodynamic equilibrium conditions, namely the pH and the aqueous speciation as well as saturation indices of mineral phases. Finally, the results suggest that the generation of hydrogen, combined with an increase in temperature (between 30 deg. C and 80 deg. C) and a decrease in relative humidity (from 100% to 30%), should increase the chemical reactivity of the pore water-rock-gas system. (authors)

  8. IONIC TRANSPORT THROUGH SHALES. INFLUENCE OF THE MICROSTRUCTURE AND OF THE MINERAL/WATER INTERFACE. APPLICATION TO THE ARGILLITES OF THE BURE'S SITE (MEUSE/HAUTE MARNE)

    OpenAIRE

    Leroy, Philippe

    2005-01-01

    Negative charge excess at the surface of clay minerals coupled with their high specific surface area implies that clay-rich media have transport properties very favourable to radioactive waste storage. Given their low hydraulic conductivity, diffusion is the main transport mechanism in these media. The goal of this research was to experimentally realize and validate a mechanistic model of transport in compact clay-rich media including a triple layer model. We have developed a transport model ...

  9. 15 years of in situ cement–argillite interaction from Tournemire URL: Characterisation of the multi-scale spatial heterogeneities of pore space evolution

    International Nuclear Information System (INIS)

    The solution selected by some countries to isolate radioactive wastes from the biosphere for up to one million years in deep geological repositories includes a multi-barrier disposal design, with steel canister, bentonite and cement materials. The geochemical contrast between such materials and the host rock formation creates perturbations potentially altering the confinement properties of the formation. In this context, the French Institute for the Radiological protection and Nuclear Safety (IRSN) have developed an in situ experimental programme based on the study of cement/argillaceous formation interfaces in their Underground Research Laboratory at Tournemire (Aveyron, France). An in situ engineered analogue of a cement/clay-rock interface which has undergone 15 years of interaction has been characterised. Such important interaction time for an in situ engineered analogue provides a bridge between laboratory-derived data and the long time scale of safety assessment modelling. As the mineralogical and petrological investigations have already been published, this work presents for the first time a quantitative characterisation of the spatial distribution of the porosity in the cement and the clay-rock in terms of time scale and design. Interfaces have been characterised using an autoradiography technique in addition to petrophysical measurements. This technique enables visualisation and quantification of the spatial distribution of the porosity using 2D mapping of decimetric-scale specimens. Thus autoradiographs allow highlighting the relationship between the field heterogeneities and the pore space evolution in each material in contact. Moreover, the porosity measurements show a clogging of the porosity in the clay-rock while the porosity increases in the cement. The extension of the porosity evolution extends to a centimetre on both sides of the interface but is heterogeneously distributed in space as a function of the fissure network and interface geometries. The connected fissure network visualised using autoradiography in the clogged area could permit solute (e.g. radionuclide) transport and may also be interpreted as an evolution of the mechanical properties of the clay-rock formation upon alkaline perturbation. This set of data, with the spatial quantification of the porosity in both cement and clay materials will be useful to constrain reactive transport modelling and thus to predict long term evolution of an engineered barrier.

  10. Reconstitution of fluid paleo-circulations and element migrations in the environments of Oklo's natural nuclear reactors (Gabon) and of Tournemire's argillites (France)

    International Nuclear Information System (INIS)

    To better characterize the mobilization and migration process in rocks, a petrological and geochemical study of fluid paleo-circulation through fractures has been made in two different sites: (1) The environment of natural nuclear reactors from Proterozoic Oklo uranium ores (Gabon). The Archean basement typical of TTG series and the sandstones-pelites series of the Franceville basin are affected by a fracturing mainly filled by quartz-daphnite-calcite-sulfides and barren ou mineralized bitumens. Three paragenetic stages has been correlated to three regional structural phases. During the first extensional phase, a low saline (1.7-6.5 wt% NaCl), heated in the basement (190-210 deg. C) and impoverished in 18O meteoric recharge is injected into the basin, along major N-S faults. It was responsible of silicification. The circulation of diagenetic brines is able to leach U, Pb, Zr, REEs and P resulting from accessory minerals alteration, at the basin-scale between 2104 Ma and 1719 Ma (Pb/Pb isochrone obtained on galena incorporated in zircons). These brines are responsible of anomalous Th/La ratios (1.8) of FA silicified sandstones higher than those (0.25) of most of Archean and Proterozoic metasediments. They are highly chlorine, calco-sodic ([Cl] > 6 m, from 28 wt% NaCl to 30 wt% CaCl2), equilibrated with carbonate and evaporitic layers of FA sandstones, with low temperatures (130 deg. C) and rich in Ca, Li and Br. They are expulsed laterally due to the compaction of FA sandstones, and upwards along sub-vertical fractures. During the second extensional phase, the mineralization stage, mainly controlled by N-S faults corresponds to a mixing (155-220 deg. C) between the brines, the meteoric recharge and hydrocarbons C9 and C10-rich fluids derived from organic matter maturation in the FB pelites. The interaction of the three fluids is responsible of the mineralization in sandstones and in calcites displaying an organic carbon origin (δ13C=-10 to -15 0/00 vs. PDB). The low to moderately saline (3-18 wt% NaCl) fluids with higher temperatures (200-550 deg. C), containing traces of O2, CH4 and CO2 are related to the reactors functioning and cooling with local silicification events. During the last compressional phase, the fluid paleo-circulations are mainly responsible of barren calcite crystallization (δ13C= 0 to -5 0/00 vs. PDB). (2) The Toarcian shales from experimental IPSN site in the Tournemire tunnel (Aveyron, France). Four mineral parageneses (calcite, calcite and framboidal pyrite, calcite and cubic pyrite, and calcite and barite) have been distinguished in fractures induced by compressional Pyrenean tectonic activities. The major- and trace-element contents, and the 87Sr/86Sr isotopic ratios (0.70847-0.70852) of the vein calcite are buffered by the surrounding shales, strongly suggesting short-distance migrations of the elements considered. Low uranium and high iron contents of the vein calcite suggest circulation of reducing fluids. However, an external origin for the carbonate fillings of the main fault, obtained with 87Sr/86Sr isotopic ratios (0.70841 and 0.70858), and of positive Eu anomalies in the REE patterns, cannot be excluded. This study shows that the competition between chemical aggressiveness of diagenetic fluids and buffering from surrounding rocks, with P-T conditions control determine or regulate the scale of element migration which has been important at Oklo and moderate at Tournemire. (author)

  11. Evolution history and U-metallogenic geological conditions of Songliao basin

    International Nuclear Information System (INIS)

    Songliao basin is located in the eastern part of in-situ leachable sandstone-type uranium metallogenetic belt of Middle Asia, where oil-gas-bearing and coal-bearing and red continental clastic rock formations are developed. Interlayer oxidized zone and argillite-sandstone-argillite sequence occur in red clastic rock formation with ideal artesian and circulating system of ground water. The basin must be the favourable area for prospecting in-situ leachable sandstone-type uranium deposit

  12. Can clays ensure nuclear waste repositories?

    OpenAIRE

    Zaoui, A.; Sekkal, W.

    2015-01-01

    Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmori...

  13. Impact de la fissuration sur les propriétés de rétention d'eau et de transport de gaz des géomatériaux : Application au stockage géologique des déchets radioactifs

    OpenAIRE

    M'Jahad, Sofia

    2012-01-01

    In the context of geological disposal of radioactive waste, this work contributes to the characterization of the effect of diffuse damage on the water retention and gas transfer properties of concrete (CEM I and CEM V) selected by Andra, Callovo-Oxfordian argillite (host rock) and argillite / concrete interfaces. This study provides information on the concrete microstructure from Mercury porosimetry intrusion and water retention curves: each concrete has a distinct microstructure, CEM I concr...

  14. Effect of damage on water retention and gas transport properties geo-materials: Application to geological storage of radioactive waste

    International Nuclear Information System (INIS)

    In the context of geological disposal of radioactive waste, this work contributes to the characterization of the effect of diffuse damage on the water retention and gas transfer properties of concrete (CEM I and CEM V) selected by Andra, Callovo-Oxfordian argillite (host rock) and argillite / concrete interfaces. This study provides information on the concrete microstructure from Mercury porosimetry intrusion and water retention curves: each concrete has a distinct microstructure, CEM I concrete is characterized by a significant proportion of capillary pores while CEM V concrete has a large proportion of C-S-H pores. Several protocols have been developed in order to damage concrete. The damage reduces water retention capacity of CEM I concrete and increases its gas permeability. Indeed, gas breakthrough pressure decreases significantly for damaged concrete, and this regardless of the type of concrete. For argillite, the sample mass increases gradually at RH = 100%, which creates and increases damage in the material. This reduces its ability to retain water. Otherwise, water retention and gas transport properties of argillite are highly dependent of its initial water saturation, which is linked to its damage. Finally, we observed a clogging phenomenon at the argillite/concrete interfaces, which is first mechanical and then hydraulic (and probably chemical) after water injection. This reduces the gas breakthrough pressure interfaces. (author)

  15. The contribution of tracers in understanding transportation processes in indurated argillaceous formations

    International Nuclear Information System (INIS)

    In a first part, the author recalls briefly the properties of the two argillaceous formations studied in this HDR report: the Toarcian/Domerian argillite and the Opalinus clay of Mont Terri. At first, have been described the two undamaged argillite materials and then the damaged Tournemire argillite. The second part gives the results obtained from the researches on the undamaged rock with natural tracers and with approaches using artificial tracers. The third part deals with the study of the damaged rock in separating natural perturbations of those of anthropogenic origin. At last, the conclusion gives the guiding thema of this research work and the main long-term future prospects that may result. (O.M.)

  16. Experimental study and modelling of physico-chemical mechanisms of clay-concrete interactions in the radioactive waste geological disposal context

    International Nuclear Information System (INIS)

    These research works are carried out as part of the radioactive wastes geological disposal feasibility study. The current option developed by Andra, includes several cementitious materials in contact with the surrounding Callovo-Oxfordian (COX) (an argillite). Concretes and argillite present very different pore solutions (ionic concentrations and pH). Controlled by the concentrations differences, the aqueous species diffusion in the solids generates chemical and physical disturbances. This study is based on experimental, analytical and numerical works, in order to identify the mechanisms controlling the clayey environment influence on cementitious materials. (author)

  17. Iron-clay reactivity in radioactive waste disposal - Impacts of bacterial activities and heterogeneities

    International Nuclear Information System (INIS)

    This study focuses on the interactions between two materials that may be introduced in a geological disposal of radioactive waste: metallic materials such as the high-level waste overpack, and clay materials such as the clay host rock. Indeed, the interactions between these two materials in such conditions could induce a change of their initial confinement properties. This work aimed at determining the influence of heterogeneities (technological gaps and fractures) and bacterial activities on these interactions, in terms of evolution of chemical and hydraulic properties of clayey materials. To this end, two percolation cells have been conducted during 13 months: the first one with two bacteria (SRB, IRB), the second one without bacteria. These experiments, carried out at 60 C, involved circulating synthetic water representative of the Tournemire pore water through iron powder and through Toarcian artificially cracked argillite from Tournemire. An iron rod was also placed into the argillite. Thus, solid characterizations (SEM, SEM/EDS, Raman, XRD, X-ray tomography) allowed the study of both interfaces: the iron powder/argillite interface and the iron rod/argillite interface. The water probably circulated into the crack during the entire test, which was confirmed by reactive transport modeling with the HYTEC reactive transport code. However, no secondary phase was identified in the crack. In addition, bacteria survival in the biotic cell was confirmed during the experiment by monitoring their population and by analyzing their genetic diversity at the end of the experiment. A strong decrease in sulfate concentration was measured in the output, which confirms the SRB activity. Solid characterization conducted at the end of the experiments have highlighted, with and without bacteria, the occurrence of magnetite and chukanovite in the iron powder, the latter being mainly located close to the argillite interface. In the argillite, a Fe-enriched zone (10 μm) was

  18. Mineralogical evolution of argilites in dehydrated-oxidised zones: the example of the argilitic walls from Tournemire tunnel

    International Nuclear Information System (INIS)

    Digging of underground work such as that of the Tournemire tunnel in a Toarcian argillite formation, has an impact on the surface mineralogy of the rock blocks. In spite of its very low water content, the argillite is reactive as a consequence of the modification of the redox conditions. Thus, atmospheric oxygen in presence of adsorbed water induces pyrite corrosion and formation of secondary mineral phases such as gypsum, celestite, jarosite and Fe-hydroxides, which play a significant role on the water-rock equilibria of the mechanically disturbed zone. (authors)

  19. Iron/clay interaction in presence of bacteria

    International Nuclear Information System (INIS)

    A water percolation cell has been designed to assess the impact of bacteria on the interaction between clay and iron. It has been shown that at the interface between argillite and bulk iron, the presence of bacteria has led to local corrosion made of iron sulphide and pitting. (A.C.)

  20. Rock property analysis of core samples from the Calico Hills UE25a-3 borehole, Nevada Test Site, Nevada

    International Nuclear Information System (INIS)

    Core samples from the Calico Hills UE25a-3 borehole were measured for density, porosity, resistivity, induced polarization, compressional sonic velocity, and magnetic properties as part of the radioactive waste disposal site identification studies currently in progress at the Nevada Test Site. The samples were representative of three distinct subunits of argillite underlain by a marble section, all believed to be in the Mississippian part of the Eleana Formation. Because of a history of regional structural deformation, subsequent fracturing, and various degrees of fracture rehealing, the rock properties measured are highly variable within each principal rock section. Porosity changes affect virtually all rock properties measured except for magnetic intensity, and grain-density evidence shows that compositional differences are also a factor in producing the observed variability in rock properties. The induced polarization response is high in the argillite section owing to the concentration of pyrite, magnetite, and possible clay minerals within the fracture-filling material. The relatively high remanent and induced magnetization of the altered argillite subunit is a distinguishing feature of that section of argillite

  1. Bedrock Geology of the Thiel Mountains, Antarctica.

    Science.gov (United States)

    Ford, A B; Aaron, J M

    1962-09-01

    Cordierite-bearing, hyper-sthene-quartz monzonite porphyry, the most widespread rock unit, is intruded by biotite granite and porphyritic biotite granite. Sedimentary and metasedimentary rocks, mainly quartzites and argillites, have been metamorphosed locally to hornfels and have been involved in high-angle faulting. Shear zones are common in the plutonic rocks. PMID:17732193

  2. Laboratory studies of radionuclide distributions between selected groundwaters and geologic media

    International Nuclear Information System (INIS)

    Extensive studies of the behavior of plutonium and americium in pH 8 groundwaters were made, particularly with respect to container sorption, filtering, and centrifugation. Significant improvements in the method used for measuring sorption ratios for these elements were developed, and their sorption-desorption ratios on argillite and tuff were measured. Effects of particle size, temperature, sampling location, mineralogy, and time were investigated for these elements. The chemical composition of the water was found to be a major factor that governs sorption behavior for some elements. Studies of the sorption of strontium, cesium, barium, cerium, europium, uranium, and americium on Hainesville salt dome materials were made under aerobic and anoxic (< 0.2 ppm oxygen) conditions using two synthetic groundwaters: one represented the Wilcox aquifer in the Hainesville region and the second was a dilute brine. Studies of the sorption of strontium, cesium, barium, cerium, europium, and uranium(VI) on granite and argillite were made under anoxic (< 0.2 ppm oxygen) conditions and the results were compared to earlier measurements made under aerobic conditions. The sorption of uranium(VI) on argillite under atmospheric conditions was investigated. Measurements of migration rates in crushed granite, argillite, and tuff were made and compared with batch results. Infiltration experiments involving the forced injection of activity into intact and fractured cores were also performed. Microautoradiographic techniques were used to detect specific sorption sites. This latter technique was also used to characterize the sorption of plutonium and neptunium on polished thin-sections of alluvium, granite, tuff, and argillite and to assess the amount of aggregation that occurred. Additional physical and chemical characterizations of the materials used in these studies were made, and new analytical techniques were developed

  3. Scientific investigation in deep boreholes at the Meuse/Haute Marne underground research laboratory, northeastern France

    International Nuclear Information System (INIS)

    From 1994 to 1996, the preliminary investigation carried out by Andra, identified a sector favourable for hosting a laboratory in argillaceous Callovo-Oxfordian formation which has a thickness of 130 m and lies more than 400 m below ground level. In November 1999 Andra began building an Underground Research Laboratory (URL) with a 3D seismic survey over 4 km2. From 2000 to 2004, large programs of boreholes were carried out on site and on the sector in order to define the characteristics of formations, to improve the regional geological and hydrogeological knowledge and to provide an accurate definition of structural features in Callovo-Oxfordian argillites and Dogger limestones. These drilling programs have provided a fine characterization of the argillites on the laboratory area and a good correlation of geological properties at a sector scale. (author)

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

    International Nuclear Information System (INIS)

    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.

  5. Clay minerals reactivity under thermal gradient

    International Nuclear Information System (INIS)

    The argillaceous materials properties could be favourable to the radioelements confinement in high activity and thermogenic nuclear waste disposal. This study relates to the transformations induced on these materials under thermal stress and the impact on their properties. The samples were collected in the vicinity of a natural analogue: a basaltic intrusion in an argillaceous formation (argillites of Laumiere, Aveyron, France). This volcanic event has functioned for an unreachable time in a laboratory. The study of the mixed-layered illite-smectite minerals (I-S), major minerals of these argillites, shows an illitisation at the basaltic intrusion contact. The thin and disturbed variation of an index of crystallinity of the I-S corresponds to the influence of the geological context. Laumiere highlighted determining parameters (smectite formation during hydrothermal alteration) which has influenced the evolution of argillaceous materials in thermal context. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Hydrogen transfer experiments and modelization in clay rocks for radioactive waste deep geological repository

    International Nuclear Information System (INIS)

    Gases will be generated by corrosion of high radioactive waste containers in deep geological repositories. A gas phase will be generated. Gas pressure will build up and penetrated the geological formation. If gases do not penetrate the geological barrier efficiently, the pressure build up may create a risk of fracturing and of creation of preferential pathways for radionuclide migration. The present work focuses on Callovo-Oxfordian argillites characterisation. An experiment, designed to measure very low permeabilities, was used with hydrogen/helium and analysed using the Dusty Gas Model. Argillites close to saturation have an accessible porosity to gas transfer that is lower than 0,1% to 1% of the porosity. Analysis of the Knudsen effect suggests that this accessible network should be made of 50 nm to 200 nm diameter pores. The permeabilities values were integrated to an ANDRA operating model. The model showed that the maximum pressure expected near the repository would be 83 bar. (author)

  8. Analysis of the phenomenon of material expansiveness in tunnels built in anhydrite. Outcomes and experiences

    OpenAIRE

    Del Campo, J. M.; J. C. Guerra; Fernández-Ordóñez, D.

    2012-01-01

    The serious geotechnical problems arising in many tunnels bored in material giving rise to stability problems as a result of being expansive, makes the water channelizers. These are materials which are easily washed with sulphates dissolving with water causing the massif to become decompressed and to remould, aggravating and transferring the problem beyond the tunnel’s immediate environment. In the particular case of layers of anhydrite between argillite, it also happens that the primary supp...

  9. Palaeogeography and palaeoecology of early Floian (Early Ordovician) cephalopods from the Upper Fezouata Formation, Anti-Atlas, Morocco

    OpenAIRE

    Kröger, B; Lefebvre, B.

    2012-01-01

    In the central Anti-Atlas (Morocco), the Early Ordovician succession consists of about 1000 m of fossiliferous argillites and siltstones. The Upper Fezouata Formation (Floian) contains a comparatively rich and abundant cephalopod association. A small collection of these cephalopods is described herein for the first time. The cephalopods are interpreted as autochthonous or parautochthonous, representing a fauna, which originally lived nektobenthically in the open water above the sediments or r...

  10. Clays in radioactive waste disposal

    OpenAIRE

    Delage, Pierre; CUI, Yu-Jun; Tang, Anh-Minh

    2010-01-01

    Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, Fran...

  11. Impact of chemical oxidation and water acidification on the mineralogical and physico-chemical properties of the Tournemire argillaceous formation

    International Nuclear Information System (INIS)

    The French Institute for Protection and Nuclear Safety (IPSN) has selected a site near Tournemire (France) for research programmes on deep geological waste disposal in clay-rich rock formation. A railway tunnel was built about 100 years ago through the thick indurated Toarcian argillite of the Tournemire Massif and two galleries were constructed five years ago. They are used to study the evolution of rock mineralogical composition, texture, water content and water-rock interactions in the excavated disturbed zone. Multi-scale and multi-technique investigations were carried out on the evolution of physical and mineralogical rock properties. Experiments and numerical modelling were used to predict changes due to water-rock interactions and subsequent rock mineralogy and water chemistry modifications. The argillite consists of detrital clay-rich layers and carbonate layers. Pyrites are always present in significant amounts (2 to 2.5 %). The rock presents very low porosity and very low water content (around 3 %). Leaching experiments show that the interstitial water is Na and SO4-rich and Cl-poor. The tunnel and galleries digging induces fracture formation. In the altered samples, the clay particles show a better orientation in the stratification plan, which increases the porosity. The oxidation effect yields to mineralogical transformation on the surfaces of the argillite: oxidation of pyrite, dissolution of calcite, dissolution of illite layers in interstratified I/S and formation of gypsum, Fe-oxi/hydroxides, celestite and jarosite. During cycles of hydration/dehydration, condensation water interacts with the argillite and quickly becomes Ca and SO4-rich. The local dissolution of clay particles leads to an increase of the chloride and potassium water content. These phenomena are important for the consideration of the underground work stability, especially the evolution of the water-rock equilibria during the re-hydration of the excavated disturbed zones. (author)

  12. Interpretations of magnetic anomalies at a potential repository site located in the Yucca Mountain area, Nevada Test Site

    International Nuclear Information System (INIS)

    In the Yucca Mountain area near the southwestern border of the Nevada Test Site, studies of the relation of magnetic properties to geologic features have provided structural information at and near a potential site for storage or radioactive waste. Interpreted features include a tabular mass of magnetized sedimentary rock beneath thick deposits of volcanic rock, and 11 major faults that strike generally northward and displace magnetized volcanic rock. A positive anomaly in a high-altitude aeromagnetic survey over exposures of strongly magnetized argillite of the Eleana Formation extends westward 20 km into the site area where interpretations indicate an argillite thickness of 800 m at a depth of 2.25 km. The high magnetite content of the argillite is not typical of the region, and was probably introduced by the heating effects of an underlying pluton. The basis for mapping traces of faults, and identifying their upthrown sides, was developed elsewhere at Yucca fault in the relatively simple volcanic terrains of Yucca Flat. In the site area, analyses of aeromagnetic anomalies from a low-altitude east-west aeromagnetic survey show the Topopah Spring Member of the Paintbrush Tuff as the primary source of anomalies from faulted sequences of volcanic rock. Faults related to belts of positive and negative anomalies surrounding the site have been identified. The possibility that an east-west pattern of anomalies is related to structure crossing the site was investigated by a recent aeromagnetic survey flown at low altitude in north-south directions. A significant reduction in amplitude of these anomalies resulted when effects of the deeply buried argillite were removed. The remaining anomalies over the site can be explained by a change in lateral extent, or magnetic properties, of volcanic units beneath the Topopah Spring Member. 37 references, 22 figures, 1 table

  13. Post-middle Miocene accretion of Franciscan rocks, northwestern California.

    Science.gov (United States)

    McLaughlin, R.J.; Kling, S.A.; Poore, R.Z.; McDougall, K.; Beutner, E.C.

    1982-01-01

    Deformed sedimentary rocks assigned to the Franciscan assemblage in the King Range S of Cape Mendocino, N California, are dominantly deep-water argillite and sandstone occurring as thick- to thin-bedded, locally channelized marine turbidities of arkosic to andesitic volcaniclastic composition. The King Range appears to be a displaced terrane of oceanic basement overlain by Palaeogene(?) and Neogene sedimentary and igneous rocks of continental and oceanic derivation.-Authors

  14. Petrology, Magnetic susceptibility, Tectonic setting and mineralization associated with Plutonic and Volcanic Rocks, Eastern Bajestan and Taherabad, Iran

    OpenAIRE

    Malihe Ghoorchi; Sayide Saadat; Alireza Ashouri

    2009-01-01

    Study area is located in district of Bajestan and Ferdows cities, NE of Iran. Structurally, this area is part of Lut block. The oldest exposed rocks, to the north of intrusive rocks and in Eastern Bajestan, are meta-chert, slate, quartzite, thin-bedded crystalline limestone and meta-argillite. The sedimentary units are: Sardar Formation (Carboniferous), Jamal Formation (Permian), Sorkh Shale and Shotori Formations (Triassic), carbonateous rocks (Cretaceous) and lithostratigraphically equivale...

  15. Fracture Mechanics Characterization of an AnisotropicGeomaterial

    OpenAIRE

    Cravero, Masantonio; Iabichino, Giorgio; Valente, Silvio; Fidelibus, Corrado; Barpi, Fabrizio

    2012-01-01

    Argillites are considered worldwide as potential host rock for high level radioactive waste given the low permeability and strong adsorption potential. However, the excavation of the galleries of a repository would produce a disturbed zone around the boundaries rich of new fractures which may enhance the conductivity of the rock along the gallery axis. Several mine-by experiments have been performed in underground rock labs to investi- gate the features of the disturbed zone. In Mont Terri UR...

  16. A non-tectonic origin for the present day stress field in the sedimentary Paris Basin

    Science.gov (United States)

    Cornet, Francois; Magnenet, Vincent

    2016-04-01

    The large scale stress patterns observed in intraplate area is generally considered to result from far-field boundary forces that drive plate tectonics. However, no present day deformation has been detected in the Paris Basin, yet significant deviatoric stresses are measured in limestone formations observed above soft argillite layers encountered in this region at depths close to 500m. Further, the pore pressure measured in the argillite is larger than that measured in the surrounding permeable zones. These observations suggest a presently active source of stress in this sedimentary system. We propose that this stress is not related to tectonics but to pressure solution effects activated by pore pressure transients. These transients develop in the natural fracture system that affects the limestone formations. They are linked to climatic variations and involve periods that range from thousands to hundreds of thousands years. This mechanism generates time-dependent shear stresses in soft formations and explains overpressures observed in the very low permeability argillite. This mechanism may be modeled by different visco-elastic behaviors for the various formations. It outlines the influence of time dependent material properties on the present day stress field. These results imply that the viscoelastic properties of sedimentary formations raise a strong difficulty for extrapolating measured surface deformations to basement rocks in domains of very slow tectonics.

  17. Microbial activity in a deep underground HLW disposal cell

    International Nuclear Information System (INIS)

    The research program conducted by IRSN on microbial activity in the context of deep underground radioactive waste disposal is focused on the potential impact of bacteria on the corrosion of carbon steel materials involved in the design of high level waste (HLW) disposal cells developed in France by Andra. This program combines two different approaches: firstly, the evaluation of biodiversity of argillite, from undisturbed and disturbed (gallery wall, excavation damaged zone, presence of metallic platelets..) samples and secondly, the development of a conceptual model for development of microbial activity in a HLW disposal cell based on mass and energy balances. At this stage, it is worth noting that the effects of high radiation have not been taken into account. The characterization of biodiversity of the Toarcian argillite of Tournemire (experimental tunnel operated to develop IRSN skills in earth sciences) has shown that even if the argillite probably acts as a natural selective substratum for bacterial colonization, exogenous microorganisms may develop within disturbed areas. Indeed, the observed bacterial diversity tends to depend on the different oxygen and humidity conditions, and also probably on space availability. This characterization also highlighted the presence of a sulphate-reducing and iron-reducing bacterium capable to resist to high temperatures in a sample collected by scratching a steel platelet. Besides, the preliminary conceptual model of bacterial development has shown that iron-reducing and sulphate-reducing bacteria may be able to grow in the environment of HLW disposal cell. (orig.)

  18. Influence of reaction kinetics and mesh refinement on the numerical modelling of concrete/clay interactions

    Science.gov (United States)

    Marty, Nicolas C. M.; Tournassat, Christophe; Burnol, André; Giffaut, Eric; Gaucher, Eric C.

    2009-01-01

    SummaryLarge quantities of cements and concretes need to be incorporated in geological disposal facilities for long-lived radwaste. An alkaline plume diffusing from an aged concrete (pH ˜ 12.5) through argillite-type rocks has been modelled considering feedback of porosity value variations on transport properties using the reactive transport code TOUGHREACT. The mineralogical composition of the argillite is modified at the interface with the concrete. Diffusion of cementitious elements leads to rapid and strong porosity occlusion in the argillite. Numerical results show that both reaction rates and spatial refinement affect mineralogical transformation pathways. The variations in porosity and the extension of the zone affected by the alkaline perturbation are compared at different times. The major effects of mineral precipitation under kinetic constraints, rather than local equilibrium, are a delay in the porosity clogging and an increase in the extension of the alkaline perturbation in the clay formation. The same time-delay rise for the porosity occlusion also appears for the roughest spatial resolutions. A simulation as representative as possible of temporal and spatial scales of cementation processes must then be supported by more comparative data such as long term experimental investigations or natural analogues.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  20. Mass Transfer and Porous Media (MTPM)

    Energy Technology Data Exchange (ETDEWEB)

    Rotenberg, B.; Marry, V.; Malikova, N.; Vuilleumier, R.; Giffaut, E.; Turq, P.; Robinet, J.C.; Diaz, N.; Sardini, P.; Goutelard, F.; Menut, D.; Parneix, J.C.; Sammartino, S.; Pret, D.; Coelho, D.; Jougnot, D.; Revil, A.; Boulin, P.F.; Angulo-Jaramillo, R.; Daian, J.F.; Talandier, J.; Berne, P.; Cochepin, B.; Trotignon, L.; Bildstein, O.; Steefel, C.; Lagneau, V.; Van der Lee, J.; Birchall, D.J.; Harrington, J.F.; Noy, D.J.; Sellin, P.; Bildstein, O.; Piault, E.; Trotignon, L.; Montarnal, P.; Deville, E.; Genty, A.; Le Potier, C.; Imbert, C.; Semete, P.; Desgree, P.; Fevrier, B.; Courtois, A.; Touze, G.; Sboui, A.; Roberts, J.E.; Jaffre, J.; Glaus, M.A.; Rosse, R.; Van Loon, L.R.; Matray, J.M.; Parneix, J.C.; Tinseau, E.; Pret, D.; Mayor, J.C.; Ohkubo, T.; Kikuchi, H.; Yamaguchi, M.; Alonso, U.; Missana, T.; Garcia-Gutierrez, M.; Patelli, A.; Siitari-Kauppi, M.; Leskinen, A.; Rigato, V.; Samper, J.; Dewonck, S.; Zheng, L.; Yang, Q.; Naves, A.; Dai, Z.; Samper, J.; Wolfsberg, A.; Levitt, D.; Cormenzana, J.L.; Missana, T.; Mingarro, M.; Schampera, B.; Dultz, S.; Riebe, B.; Samper, J.; Yang, Q.; Genty, A.; Perraud, D.; Poller, A.; Mayer, G.; Croise, J.; Marschall, P.; Krooss, B.; Matray, J.M.; Tanaka, T.; Vogel, P.; Lavanchy, J.M.; Enssle, C.P.; Cruchaudet, M.; Dewonck, S.; Descostes, M.; Blin, V.; Radwan, J.; Poinssot, C.; Mibus, J.; Sachs, S.; Devol-Brown, I.; Motellier, S.; Tinseau, E.; Thoby, D.; Marsal, F.; DeWindt, L.; Tinseau, E.; Pellegrini, D.; Bauer, A.; Fiehn, B.; Marquardt, Ch.; Romer, J.; Gortzen, A.; Kienzler, B

    2007-07-01

    This session gathers 48 articles (posters) dealing with: interlayer / micro-pore exchange of water and ions in clays: a molecular dynamics study; the multi-scale characterisation of mineral and textural spatial heterogeneities in Callovo-Oxfordian argilite and its consequence on solute species diffusion modelling; the diffusion of ions in unsaturated clay rocks: Theory and application to the Callovo- Oxfordian argillite; the porous media characterization with respect to gas transfer in Callovo Oxfordian argillite; the predictions on a 2-D cementation experiment in porous medium: intercomparison on the Comedie project; the large-scale gas injection test (LASGIT) at the Aespoe hard rock laboratory in Sweden; simulating the geochemical coupling between vitrified waste, canister and near-field on the alliances platform; toward radionuclide transport calculations on whole radioactive waste disposal with CAST3M platform; the experimental study of the water permeability of a partially saturated argillite; a mixed hexahedral finite elements for Darcy flow calculation in clay porous media; the diffusive properties of stainless steel filter discs before and after use in diffusion experiments with compacted clays; the structural organization of porosity in the Opalinus clay at the Mont Terri Rock Laboratory under saturated and unsaturated conditions; the evaluation of pore structure in compacted saturated Bentonite using NMR relaxometry; diffusion coefficients measurement in consolidated clays: a combination of micro-scale profiling and solid pore structure analyses; the numerical interpretation of in-situ DIR diffusion experiments on the Callovo- Oxfordian clay at the Meuse/Haute-Marne URL the identification of relative conductivity models for water flow and solute transport in unsaturated compacted Bentonite; diffusion experiments in Callovo- Oxfordian clay from the Meuse/Haute-Marne URL, France: experimental setup and data analyses; the transport in organo

  1. Mass Transfer and Porous Media (MTPM)

    International Nuclear Information System (INIS)

    This session gathers 48 articles (posters) dealing with: interlayer / micro-pore exchange of water and ions in clays: a molecular dynamics study; the multi-scale characterisation of mineral and textural spatial heterogeneities in Callovo-Oxfordian argilite and its consequence on solute species diffusion modelling; the diffusion of ions in unsaturated clay rocks: Theory and application to the Callovo- Oxfordian argillite; the porous media characterization with respect to gas transfer in Callovo Oxfordian argillite; the predictions on a 2-D cementation experiment in porous medium: intercomparison on the Comedie project; the large-scale gas injection test (LASGIT) at the Aespoe hard rock laboratory in Sweden; simulating the geochemical coupling between vitrified waste, canister and near-field on the alliances platform; toward radionuclide transport calculations on whole radioactive waste disposal with CAST3M platform; the experimental study of the water permeability of a partially saturated argillite; a mixed hexahedral finite elements for Darcy flow calculation in clay porous media; the diffusive properties of stainless steel filter discs before and after use in diffusion experiments with compacted clays; the structural organization of porosity in the Opalinus clay at the Mont Terri Rock Laboratory under saturated and unsaturated conditions; the evaluation of pore structure in compacted saturated Bentonite using NMR relaxometry; diffusion coefficients measurement in consolidated clays: a combination of micro-scale profiling and solid pore structure analyses; the numerical interpretation of in-situ DIR diffusion experiments on the Callovo- Oxfordian clay at the Meuse/Haute-Marne URL the identification of relative conductivity models for water flow and solute transport in unsaturated compacted Bentonite; diffusion experiments in Callovo- Oxfordian clay from the Meuse/Haute-Marne URL, France: experimental setup and data analyses; the transport in organo

  2. Experimental study and modeling of the propagation of an alkaline concentration wave coming from a cement matrix an passing through the argilite of the Meuse / Haute-Marne laboratory; Etude experimentale et modelisation de la propagation d'une onde de concentration alcaline issue d'une matrice cimentiere a travers l'argilite du site du laboratoire Meuse / Haute-Marne

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, Th

    2001-12-01

    The propagation of an alkaline wave through a clay rock has been investigated- The wave is generated by a cementitious matrix through the Callovo-Oxfordian argillite of the Meuse Haute-Marne Laboratory (-480 m depth). The argillite itself is composed of quartz, micas, calcite and an interstratified l/S. In order to characterise the interactions between the alkaline fluid and the argillaceous medium, dynamic column experiments have been carried out. The originality of the investigation methodology consists in exploiting the data generated from the breakthrough curves as well as from the characterisation of the solids extracted from the columns. Two types of processes having totally different reaction times have hence been thoroughly studied: - Fast surface adsorption and condensation reactions: On the one hand cation adsorption reactions by site ionisation have been characterised. They are responsible of the buffering effect of the clays. On the other hand an original reaction of calcium compound condensation in the interlayer space of the swelling clays has been revealed. These processes have been modelled and their simulations with the IMPACT calculation code showed that the models elaborated were very satisfying. - Strongly kinetically limited dissolution/precipitation reactions: The main primary phases dissolved are quartz and interstratified l/S. The precipitation of secondary phases are mainly C(A)SH and zeolites. After the injection of an alkaline fluid for 6 months at 60 deg C, the argillite is strongly amorphized but only 20 to 30% of the quartz and the interstratified I/S are dissolved. Therefore, dissolution kinetics of the primary phases and the solubility products of the main secondary phases have been determined. (author)

  3. Experimental study and modeling of the propagation of an alkaline concentration wave coming from a cement matrix an passing through the argilite of the Meuse / Haute-Marne laboratory

    International Nuclear Information System (INIS)

    The propagation of an alkaline wave through a clay rock has been investigated- The wave is generated by a cementitious matrix through the Callovo-Oxfordian argillite of the Meuse Haute-Marne Laboratory (-480 m depth). The argillite itself is composed of quartz, micas, calcite and an interstratified l/S. In order to characterise the interactions between the alkaline fluid and the argillaceous medium, dynamic column experiments have been carried out. The originality of the investigation methodology consists in exploiting the data generated from the breakthrough curves as well as from the characterisation of the solids extracted from the columns. Two types of processes having totally different reaction times have hence been thoroughly studied: - Fast surface adsorption and condensation reactions: On the one hand cation adsorption reactions by site ionisation have been characterised. They are responsible of the buffering effect of the clays. On the other hand an original reaction of calcium compound condensation in the interlayer space of the swelling clays has been revealed. These processes have been modelled and their simulations with the IMPACT calculation code showed that the models elaborated were very satisfying. - Strongly kinetically limited dissolution/precipitation reactions: The main primary phases dissolved are quartz and interstratified l/S. The precipitation of secondary phases are mainly C(A)SH and zeolites. After the injection of an alkaline fluid for 6 months at 60 deg C, the argillite is strongly amorphized but only 20 to 30% of the quartz and the interstratified I/S are dissolved. Therefore, dissolution kinetics of the primary phases and the solubility products of the main secondary phases have been determined. (author)

  4. Creep and damage in argillaceous rocks: microstructural change and phenomenological modeling

    International Nuclear Information System (INIS)

    The underground radioactive waste disposal far exceeds the period of exploitation of common civil engineering works. These specific projects require to predict the irreversible deformations over a large time scale (several centuries) in order to assess the extension and to forecast the evolution of the EDZ (Excavation Damage Zone) around the cavity. In this study, the viscosity of three sedimentary argillaceous rocks has been studied under different conditions of uniaxial compression: static or cyclic creep tests, monotonic and quasistatic tests, performed across various strata orientations. Argillaceous rocks are studied as a possible host layer for radioactive waste disposals. Indeed, they present some of the physical characteristics and mechanical properties, which are essential for being a natural barrier: low permeability, high creep potential and important holding capacity of radioactive elements. The purpose of the experimental study was to shed some light over the mechanisms governing the development of delayed deformations and damage of argillaceous rocks. It relates three rocks: an argillite from East of France, a Tournemire argillite and a marl from Jurassic Mountains. On atomic scale, viscoplastic deformations are due to irreversible displacements of crystalline defects, called dislocations. The experimental study was also supplemented with observations on thin sections extracted from the argillite and marl samples using a SEM. The aim was to identify the mechanisms responsible for the time-dependent behaviour on a microstructural scale. Analytical simulations of the mechanical behaviour of the three rocks gave parameters used in different viscoplastic models. The best modeling was obtained with the viscoplastic model which takes account of the development of volumetric strains and of the damage anisotropy. (author)

  5. Creep and damage in argillaceous rocks: microstructural change and phenomenological modeling; Fluage et endommagement des roches argileuses: evolution de la microstructure et modelisation phenomenologique

    Energy Technology Data Exchange (ETDEWEB)

    Fabre, G

    2005-06-15

    The underground radioactive waste disposal far exceeds the period of exploitation of common civil engineering works. These specific projects require to predict the irreversible deformations over a large time scale (several centuries) in order to assess the extension and to forecast the evolution of the EDZ (Excavation Damage Zone) around the cavity. In this study, the viscosity of three sedimentary argillaceous rocks has been studied under different conditions of uniaxial compression: static or cyclic creep tests, monotonic and quasistatic tests, performed across various strata orientations. Argillaceous rocks are studied as a possible host layer for radioactive waste disposals. Indeed, they present some of the physical characteristics and mechanical properties, which are essential for being a natural barrier: low permeability, high creep potential and important holding capacity of radioactive elements. The purpose of the experimental study was to shed some light over the mechanisms governing the development of delayed deformations and damage of argillaceous rocks. It relates three rocks: an argillite from East of France, a Tournemire argillite and a marl from Jurassic Mountains. On atomic scale, viscoplastic deformations are due to irreversible displacements of crystalline defects, called dislocations. The experimental study was also supplemented with observations on thin sections extracted from the argillite and marl samples using a SEM. The aim was to identify the mechanisms responsible for the time-dependent behaviour on a microstructural scale. Analytical simulations of the mechanical behaviour of the three rocks gave parameters used in different viscoplastic models. The best modeling was obtained with the viscoplastic model which takes account of the development of volumetric strains and of the damage anisotropy. (author)

  6. Cs sorption to potential host rock of low-level radioactive waste repository in Taiwan: Experiments and numerical fitting study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tsing-Hai, E-mail: txw20@psu.edu [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chen, Chin-Lung [Division of Chemical Engineering, Institute of Nuclear Energy Research, Longtan, 325, Taiwan (China); Institute of Nuclear Engineering and Science, National TsingHua University, Hsinchu 300, Taiwan (China); Ou, Lu-Yen; Wei, Yuan-Yaw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chang, Fu-Lin [Division of Chemical Engineering, Institute of Nuclear Energy Research, Longtan, 325, Taiwan (China); Teng, Shi-Ping [Institute of Nuclear Engineering and Science, National TsingHua University, Hsinchu 300, Taiwan (China)

    2011-09-15

    Highlights: {yields} We demonstrated experiments and numerical fittings of Cs sorption to argillite step-by-step in this study. {yields} Both clay model and iron oxide model were used and their influences on the goodness of fitting results were reported. {yields} The number of sorption sites dominated the goodness of fitting results. {yields} Tracer experiments could be replaced in light of reducing the amount of radioactive waste produced. - Abstract: A reliable performance assessment of radioactive waste repository depends on better knowledge of interactions between nuclides and geological substances. Numerical fitting of acquired experimental results by the surface complexation model enables us to interpret sorption behavior at molecular scale and thus to build a solid basis for simulation study. A lack of consensus on a standard set of assessment criteria (such as determination of sorption site concentration, reaction formula) during numerical fitting, on the other hand, makes lower case comparison between various studies difficult. In this study we explored the sorption of cesium to argillite by conducting experiments under different pH and solid/liquid ratio (s/l) with two specific initial Cs concentrations (100 mg/L, 7.5 x 10{sup -4} mol/L and 0.01 mg/L, 7.5 x 10{sup -8} mol/L). After this, numerical fitting was performed, focusing on assessment criteria and their consequences. It was found that both ion exchange and electrostatic interactions governed Cs sorption on argillite. At higher initial Cs concentration the Cs sorption showed an increasing dependence on pH as the solid/liquid ratio was lowered. In contrast at trace Cs levels, the Cs sorption was neither s/l dependent nor pH sensitive. It is therefore proposed that ion exchange mechanism dominates Cs sorption when the concentration of surface sorption site exceeds that of Cs, whereas surface complexation is attributed to Cs uptake under alkaline environments. Numerical fitting was conducted using two

  7. Introduction

    International Nuclear Information System (INIS)

    Introduction presents the description of book. The present book is devoted to rational processing of boron- and aluminosilicate ores, including danburite, argillite, kaolin clays , zeolites and bentonite by means of acid and chloric methods. Conducted researches on chloric and acid decomposition of boron- and aluminosilicate ores with chlorine, sulfuric and hydrochloric acids allowed to find the optimal conditions of decomposition of raw materials with high output. Physicochemical properties of initial boron- and aluminosilicate ores were studied by means of X-ray, differential thermal analysis, and silicate analysis methods.

  8. Specific features of Bazhenov suite sediments in south-eastern Nurolsk sedimentary basin (Tomsk Oblast)

    Science.gov (United States)

    Nedolivko, N.; Perevertailo, T.; Cunyi, Li; Abramova, R.

    2015-11-01

    The specific sediment features in Georgiev (J3kmgr), Bazhenov (J3vbg) and Kulomzin (K1bkl) suites, exposed by drilling in the S-E Nurolsk depression (Tomsk Oblast), were defined and described via petrographic, X-ray diffraction and fluorescence-microscopy analysis methods. The classification of agrillites was identified, the structure-texture features, composition, voids and bitumen types and their distribution were determined. It was defined that Bazhenov suite argillites are characteristic of fine-dispersion, high biogenic silica content and scattered organic matter, enriched multi-composite syngenetic bitumen (from light to resin- asphaltine), as well as fractured surface where the migration of light bitumen occurs.

  9. Laboratory studies of radionuclide distributions between selected ground waters and geologic media. Progress report, October 1--December 31, 1978

    International Nuclear Information System (INIS)

    The Los Alamos Scientific Laboratory contribution to the Waste Isolation Safety Assessment Program, Task 4, for the first quarter of FY-79 mostly involved uranium, plutonium, and americium batch sorption studies needed to extend or complete the data bases for argillite, tuff, and granite. Initial efforts have been made to develop the equipment and procedures for performing migration rate studies on crushed, consolidated, and fractured rock, and for performing measurements under controlled atmosphere conditions. Several additional analytical procedures to be utilized for chemical characterization have been developed, and several additional ethylene glycol surface area measurements have been completed

  10. Cs sorption to potential host rock of low-level radioactive waste repository in Taiwan: Experiments and numerical fitting study

    International Nuclear Information System (INIS)

    Highlights: → We demonstrated experiments and numerical fittings of Cs sorption to argillite step-by-step in this study. → Both clay model and iron oxide model were used and their influences on the goodness of fitting results were reported. → The number of sorption sites dominated the goodness of fitting results. → Tracer experiments could be replaced in light of reducing the amount of radioactive waste produced. - Abstract: A reliable performance assessment of radioactive waste repository depends on better knowledge of interactions between nuclides and geological substances. Numerical fitting of acquired experimental results by the surface complexation model enables us to interpret sorption behavior at molecular scale and thus to build a solid basis for simulation study. A lack of consensus on a standard set of assessment criteria (such as determination of sorption site concentration, reaction formula) during numerical fitting, on the other hand, makes lower case comparison between various studies difficult. In this study we explored the sorption of cesium to argillite by conducting experiments under different pH and solid/liquid ratio (s/l) with two specific initial Cs concentrations (100 mg/L, 7.5 x 10-4 mol/L and 0.01 mg/L, 7.5 x 10-8 mol/L). After this, numerical fitting was performed, focusing on assessment criteria and their consequences. It was found that both ion exchange and electrostatic interactions governed Cs sorption on argillite. At higher initial Cs concentration the Cs sorption showed an increasing dependence on pH as the solid/liquid ratio was lowered. In contrast at trace Cs levels, the Cs sorption was neither s/l dependent nor pH sensitive. It is therefore proposed that ion exchange mechanism dominates Cs sorption when the concentration of surface sorption site exceeds that of Cs, whereas surface complexation is attributed to Cs uptake under alkaline environments. Numerical fitting was conducted using two different strategies to

  11. Characterization of Building Stones Involved in Historical Masonry

    International Nuclear Information System (INIS)

    Basic physical properties, pore size distribution and hygric properties of several types of stones which are used in reconstructions of historical buildings on the territory of the Czech Republic, namely several types of sandstone and argillite, are investigated. Basic physical characteristics are measured using the water vacuum saturation method, pore distribution by mercury porosimetry. Values of water absorption coefficient and apparent moisture diffusivity are determined by methods utilizing the results of water sorptivity measurements. Water vapor transport properties are accessed by the cup method. The obtained data represents valuable information for the application of studied materials in reconstructions and renewal of historical buildings. (author)

  12. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Popp, T.; Salzer, K.; Minkley, W. [Institut fur Gebirgsmechanik GmbH, Leipzig (Germany); Gibert, D.; Nicollin, F.; Kergosien, B. [Rennes-1 Univ., GdR FORPRO (CNRS/ANDRA GdR 788) and Geosciences Rennes (CNRS/UR1 UMR 6118) (France); Bossart, P. [Federal Office for Topography, Wabern (Switzerland); Nussbaum, C. [Institut Geotechnique SA, St-Ursanne (Switzerland); Robinet, J.C.; Nguyen, M.T. [EGC Euro-Geomat-Consulting, 45 - Orleans (France); Barnichon, J.D.; Plas, F. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Ghorbani, A.; Cosenza, P.; Florsch, N. [Pierre et Marie Curie Univ., UMR 7619 Sisyphe, 75 - Paris (France); Revil, A.; Jougnot, D. [Aix-Marseille-2, UMR 6635, CNRS-CEREGE, 13 (France); Schmutz, M. [EGID, M. de Montaigne Univ., 33 - Pessac (France); Contrucci, I.; Klein, E. [Institut National de l' Environnement Industriel et des Risques (INERIS), Ecole des Mines de Nancy, 54 - Nancy (France); Cabrera, J.; Ben-Slimane, K.; Rejeb, A.; Matray, J.M.; Savoye, S. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92 - Fontenay-aux-Roses (France); Maiolino, S. [Ecole Polytechnique, Lab. de Mecanique des Solides, UMR 7649, LMS, 91 - Palaiseau (France); CETE de Lyon/LRPC de Lyon/Meca Roches/ ERA, 69 - Bron (France); Yong, S.; Loew, S.; Fidelibus, C.; Lemy, F. [Engineering Geology, ETH Zurich, Zurich (Switzerland); Frank, E. [Swiss Federal Nuclear Safety Inspectorate (HSK), Villigen (Switzerland); Chun-Liang, Zhang; Tilmann, Rothfuchs [Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS) mbH, Braunschweig (Germany)

    2007-07-01

    This session gathers 10 articles (posters) dealing with: the influence of bedding planes to EDZ evolution and the coupled HM properties of Opalinus Clay; the electrical tomography monitoring of the EDZ during the excavation of the gallery 04 in the Mont Terri rock laboratory; the seismic endoscopy and tomography of the EDZ of the gallery 04 in the Mont Terri rock laboratory; a elastoplastic damage model for saturated and unsaturated stiffness clays: description and application to the modelling of EDZ around drifts in Callovo-Oxfordian argillites; the non-invasive monitoring of water content and microcracks in argillites using spectral induced polarization; EDZ investigations by ultrasonic borehole logging in drifts of different ages excavated in argillaceous formations of the Tournemire experimental station (Aveyron, France); the excavation damaged zones in the argillaceous Tournemire site: characterisation and failure mechanisms; the hardening-based degradation factor: influence of mean stress and stiffness; the disturbance in the EDZ in the Opalinus clay at Mont Terri; and the experimental study on self-sealing capacity of clay rocks.

  13. Can clays ensure nuclear waste repositories?

    Science.gov (United States)

    Zaoui, A.; Sekkal, W.

    2015-03-01

    Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmorillonite with respect to calcite. Under anisotropic stress, we have observed a shear deformation of the assembly with the presence of broken bonds in the clay mineral, localised in the octahedral rather than the tetrahedral layers. The stress/strain curve leads to a failure strength point at 18.5 MPa. The obtained in-plane response of the assembly to perpendicular deformation is characterized by smaller perpendicular moduli Ez = 48.28 GPa compared to larger in-plane moduli Ex = 141.39 GPa and Ey = 134.02 GPa. Our calculations indicate the instability of the assembly without water molecules at the interface in addition to an important shear deformation.

  14. Evaluation of the reversibility of iodide uptake by argillaceous rocks by the radial diffusion method

    International Nuclear Information System (INIS)

    Laboratory radial in- and out-diffusion experiments were performed to investigate the reversibility of the iodide (I-) uptake by argillaceous rocks from the Tournemire site (France). At first, the suitability of the method was demonstrated by means of deuterium depleted water (DDW) diffusion experiments. The values for the DDW effective diffusion coefficient (1.7 to 2.7 x 10-11 m2 s-1) are indeed very close to those obtained from previous through-diffusion experiments carried out on Tournemire samples with tritiated water. The diffusion of chloride and bromide led to the determination of halide-accessible porosities, which are necessary to calculate the retardation factor (R) and the distribution ratio (RD). The calculated values for the halide-accessible porosity (2 to 5%) clearly indicated the effect of anionic exclusion and are consistent with previous data. On the contrary, the in-diffusion experiments performed with iodide clearly showed its uptake by argillite, with rock capacity factor values ranging from 14% to 25%. The corresponding values of RD (0.035 to 0.08 L kg-1) are one order of magnitude lower than those previously derived from batch methods. At last, the experiments of iodide out-diffusion revealed that only iodide located in the halide-accessible porosity diffused out of the rock samples, suggesting that the uptake of iodide by argillite would not be reversible or that the kinetics of desorption would be low (> 70 days). (orig.)

  15. Discovery of the copper deposits with features of the Keweenawan type in the border area of Yunnan and Guizhou provinces

    Institute of Scientific and Technical Information of China (English)

    ZHU; Bingquan(朱炳泉); HU; Yaoguo(胡耀国); ZHANG; Zhengwei(张正伟); CHANG; Xiangyang(常向阳)

    2003-01-01

    There existed intense Cu anomaly on the northeastern side of the geochemical boundary with NW strike in the border area between the Yunnan and Guizhou provinces. Through field observation, ore bodies of high-grade native coppers have been found. The copper mineralization was constrained by the ancient volcanic vents of Permian basalt eruption and the overlain strata of carbonaceous argillites. Native coppers with flaky, net veined and impregnated occurrences, fine-grained tenorites and massive chalcocites widely occur in volcanic breccias, tuffs, carbonaceous-siliceous argillites and siliceous bitumen rocks with bed thickness of about 15-80 m. Cu contents vary from 0.5% to 20%. The copper mineralization was tightly related to actinolite-tremolitization, zeolitization and bituminization and involved in extensive reduction environments. Continental flood basalts erupted in mantle plume environments usually have high Cu concentrations (~170 ×10-6 in the Emeishan basalts), which provided a copper source of mineralization. Thus, metallogenesis of the native copper deposits in the Yunnan-Guizhou border area is tightly associated with intensive crust-mantle and organic-inorganic interactions. The tremolitization and chalcocitization indicate that the metallogenic temperatures are in a range of 400-100℃. The geologic background and characteristics of ore and alteration for the native copper deposits in this area are somewhat similar to those of the Keweenawan native copper deposit in Michigan, USA.

  16. Can clays ensure nuclear waste repositories?

    Science.gov (United States)

    Zaoui, A; Sekkal, W

    2015-01-01

    Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmorillonite with respect to calcite. Under anisotropic stress, we have observed a shear deformation of the assembly with the presence of broken bonds in the clay mineral, localised in the octahedral rather than the tetrahedral layers. The stress/strain curve leads to a failure strength point at 18.5 MPa. The obtained in-plane response of the assembly to perpendicular deformation is characterized by smaller perpendicular moduli Ez = 48.28 GPa compared to larger in-plane moduli Ex = 141.39 GPa and Ey = 134.02 GPa. Our calculations indicate the instability of the assembly without water molecules at the interface in addition to an important shear deformation. PMID:25742950

  17. Assessment of microbiological development in nuclear waste geological disposal: a geochemical modeling approach

    International Nuclear Information System (INIS)

    Deep geological environments are very often poor or devoid of biodegradable organic molecules, but hydrogen could be an efficient energetic source to replace organic matter and promote redox processes such as reduction of O2, NO3-, Fe3+, SO42- and CO2. Moreover, the accessibility and availability of H2 and nutrients depend on gas/liquid permeability and their migration in the clay-stone porosity through the excavation damaged zone (EDZ). This study evaluates the spatial and temporal evolution of the geochemical conditions with regard to microbial development. The corrosion process in the argillite is investigated using numerical modeling over a period of 100,000 years. The development of bacterial biomass is estimated using potential redox reactions catalyzed by microorganisms and available nutrients. The simulations show that after the thermal peak (ca. 100-1000 years), physico-chemical conditions are favourable to support bacterial life. Relevant amounts of H2 and nutrients are released and migrate over the first 2 m of the argillite. Most of the biological redox process are localised close to the container where a high amount of magnetite is produced, providing Fe(III) (electron acceptor) that favours the development of iron-reducing bacteria (IRB). (authors)

  18. Experimental programs associated to the new 2003 drift excavation in the IRSN Tournemire site

    International Nuclear Information System (INIS)

    Evolution of the disturbed zone due to drift excavation (EDZ) is attributed to the hydro-mechanical and geochemical coupled processes. An instrumentation before the drift excavation was necessary to assess the initial state of the argillite in order to analyse the evolution of perturbation with respect to time. Sub-horizontal boreholes were instrumented for micro-seismic hydro-geological and geomechanical investigations. Two 5 m diameter circular drifts were excavated: a main drift of 40 m long and a secondary drift of 15 m long. Fracture analysis in the EDZ zone is related to the century-old railway tunnel. Evaluation of the hydraulic head perturbation due to drift excavation with three test pressure sections in a 35 m-long borehole (PH2) is made. Thickness and evolution of the EDZ with twenty high frequency accelerometers in four boreholes (MS1 to MS4) were determined. Geomechanical investigations included: deformation evolution with extensometers in two boreholes (M4, M5); - Drift convergence section; - Pressure sensors in concrete zone; -Steel support. Concrete-argillite interaction analysis with calcareous and siliceous rubbles is reported

  19. An experimental study of electrical and dielectric properties of consolidated clayey materials; Etude experimentale des proprietes electriques et dielectriques des materiaux argileux consolides

    Energy Technology Data Exchange (ETDEWEB)

    Comparon, L

    2005-06-15

    This study is devoted to the electrical and dielectric properties of consolidated clays. A better understanding of the conduction and polarization phenomena in clays is necessary to better interpret in situ measurements in terms of water saturation and texture. An experimental study was carried out on synthetic clay samples (kaolinite and smectite) compacted with various water contents, porosities and mineralogical compositions, on a large frequency range, using three laboratory setups. The electrical properties of natural argillites (from ANDRA) were then investigated. We found that the response of the synthetic samples is mainly controlled by water content on the whole frequency range; two polarization phenomena were observed, which were related to the Maxwell-Wagner polarization and the electrical double layer polarization around the clay particles. The electrical response of argillites is more complex; it is controlled by water content but also by the microstructure of the rock. In these rocks, the electrical and dielectric anisotropies are high; anisotropy was also measured for the synthetic clays. The existing models explain the high frequency limit of the dielectric permittivity of the clayey materials, but the low frequency part of the spectra ({<=}1 MHz) needs theoretical developments. (author)

  20. Elution of radionuclides through columns of crushed rock from the Nevada Test Site

    International Nuclear Information System (INIS)

    Results from the elution of radionuclides through columns of crushed tuff, granite, and argillite are presented. Good agreement between column and batch measurements on washed samples is generally observed for all three rock types. This is encouraging, since the results of batch measurements are often of value to show relative sorption under a variety of conditions, and their relevance to the migration of radionuclides under flowing conditions has been questioned. Column elution behavior depended upon sample mineralogy. For example, 85Sr gave fairly sharp, symmetric peaks on granite, argillite, and devitrified tuffs; however, on a vitrophyre, the peak was 10 to 100 times broader. For 137Cs, the most unusual behavior was found on granites, where for columns run at approx. 20 m/year, most of the cesium was retained at the load point. For all the radionuclides studied, except /sup 95m/Tc, zeolite-containing tuffs had to be run at flow rates of 103 to 104 m/year to obtain elutions, while samples composed primarily of alkali feldspar and SiO2 gave elutions of 85Sr, 137Cs, and 133Ba at flow rates of 10 to 100 m/year. Knowledge of the mineralogic compositions of tuffs and their ability to retard the migration of radionuclides is important - not only to identify the optimum horizon for a nuclear waste repository in Yucca Mountain, but also to estimate how well the repository will perform

  1. Quaternary deposits and weathered bedrock material as a source of dangerous radon emissions in Estonia

    Directory of Open Access Journals (Sweden)

    Petersell Valter

    2015-06-01

    Full Text Available The risk of dangerous radon emissions in Estonia is high, being among the highest in Europe. In almost 33 per cent of Estonian land area, the content of radon in soil-contained air exceeds the safe limit for unrestricted construction (50 kBq/m3. In such high radon-risk areas the concentration of radon in soil-contained air ranges from 50 to 400 kBq/m3, in a few cases reaching up to 2,100 kBq/m3 exceeding the permitted level for residential areas. The situation is particularly serious in the northernmost part of the country, where uranium-rich graptolite argillite (Dictyonema shale and the Obolus phosphorite are close to ground surface and their particles are constituent parts of Quaternary deposits. Radon emissions from bedrock have been investigated in detail, but to date Quaternary strata as a source of radon emissions are poorly studied. According to our measurements the highest concentrations of radon are related to tills containing clasts and fines of graptolite argillite and phosphorite. Glacial deposits include also granitoidal material, containing U, Th and K, which have been transported by glaciers from the outcrop areas of crystalline basement rocks in Finland and the Gulf of Finland. Due to weathering, outwash and repeated redeposition other genetic types are poorer in radioactive elements and they are weaker sources of radon.

  2. An experimental study of electrical and dielectric properties of consolidated clayey materials

    International Nuclear Information System (INIS)

    This study is devoted to the electrical and dielectric properties of consolidated clays. A better understanding of the conduction and polarization phenomena in clays is necessary to better interpret in situ measurements in terms of water saturation and texture. An experimental study was carried out on synthetic clay samples (kaolinite and smectite) compacted with various water contents, porosities and mineralogical compositions, on a large frequency range, using three laboratory setups. The electrical properties of natural argillites (from ANDRA) were then investigated. We found that the response of the synthetic samples is mainly controlled by water content on the whole frequency range; two polarization phenomena were observed, which were related to the Maxwell-Wagner polarization and the electrical double layer polarization around the clay particles. The electrical response of argillites is more complex; it is controlled by water content but also by the microstructure of the rock. In these rocks, the electrical and dielectric anisotropies are high; anisotropy was also measured for the synthetic clays. The existing models explain the high frequency limit of the dielectric permittivity of the clayey materials, but the low frequency part of the spectra (≤1 MHz) needs theoretical developments. (author)

  3. Direct observations of the 3D pore network of a Callovo-Oxfordian clay-stone

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Long term deep underground storage of radioactive nuclear waste is planned in the East of France within an argillaceous rock layer (the host rock), also called argillite, situated at ca. 450-500 m depth. Andra, the French national agency for nuclear waste management, is in charge of assessing the feasibility, the safety and the performance of this underground disposal. The drilling of storage tunnels generates an Excavated Damaged Zone (EDZ), where argillite is macro-cracked in various locations. This requires strengthening by different means, e.g. shotcrete or pre-fabricated concrete arches. It is also expected that underground water seepage will contribute to argillite sealing: mainly self-sealing, and sealing at the interface with concrete. Sealing phenomena include crystalline swelling of smectitic clay components of argillite and inter-particle swelling of clay minerals due to osmosis mechanisms. Small scale pores and mineral organisation of the COx clay-stone are widely acknowledged to control transfer properties of water, gas and varied solutes. In order to assess these properties, the COx small-scale structure has been imaged down to micrometric resolution by various means, including classical Scanning Electron Microscopy (SEM), X-ray computed microtomography and autoradiography. To go further into pore and mineral characterisation of COx clay-stone, the following investigations are currently under way: (i) acquiring/quantifying the 3D geometry of the pore network of undisturbed COx with a nano-metric resolution and (ii) imaging/quantifying the small-scale (mm-nm) structure of self-sealed volumes. The FIB (Focused Ion Beam) /SEM technique allows performing 3D observations of solid volumes of ca. a few microns, with a resolution of about ten nanometers, by acquiring and computing regularly spaced 2D SEM images. This technique provides quantification of the 3D spatial distribution mainly of macro- and meso

  4. Geostatistical characterization of the Callovo-Oxfordian clay variability: from conventional and high resolution log data

    International Nuclear Information System (INIS)

    Andra (National Radioactive Waste Management Agency) has conducted studies in its Meuse/Haute-Marne Underground Research Laboratory located at a depth of about 490 m in a 155-million-year-old argillaceous rock: the Callovo-Oxfordian argillite. The purpose of the present work is to obtain as much information as possible from high-resolution log data and to optimize their analysis to specify and characterize space-time variations of the argillites from the Meuse/Haute-Marne site and subsequently predict the evolution of argillite properties on a 250 km2 zone around the underground laboratory (transposition zone). The aim is to outline a methodology to transform depth intervals into geological time intervals and thus to quantify precisely the sedimentation rate variation, estimate duration; for example the duration of bio-stratigraphical units or of hiatuses. The latter point is particularly important because a continuous time recording is often assumed in geological modelling. The spatial variations can be studied on various scales. First, well-to-well correlations are established between seven wells at different scales. Relative variations of the thickness are observed locally. Second, FMI (Full-bore Formation Micro-Imager, Schlumberger) data are studied in detail to extract as much information as possible. For example, the analysis of FMI images reveals a clear carbonate - clay inter-bedding which displays cycles. Third, geostatistical tools are used to study these cycles. The vario-graphic analysis of conventional log data shows one metre cycles. With FMI data, smaller periods can be detected. Variogram modelling and factorial kriging analysis suggest that three spatial periods exist. They vary vertically and laterally in the boreholes but cycle ratios are stable and similar to orbital-cycle ratios (Milankovitch cycles). The three periods correspond to eccentricity, obliquity and precession. Since the duration of these orbital cycles is known, depth intervals can

  5. Magnetic susceptibility experimental study of the rocks from north-western part of Dnieper-Donets depression

    International Nuclear Information System (INIS)

    Complete text of publication follows. Magnetic susceptibility χ of the sedimentary and effusive Devonian and Carbonian rocks from 8 bore-holes of north-western part of Dnieper-Donets depression was investigated. There are argillits, aleurolites, sandstones, limestones, anhydrites, salt, tuff breccias, tuff sandstones, marls, dolomitic limestones, basalts. The crystalline basement (Precambrian) is presented by gneisses and granite-gneisses from Stroyivska bore-hole (2976-3803m). Oil and gas perspectives are connected with Devonian deposits. Magnetic susceptibility values of the rocks vary in wide interval: from 5,4 x 10-5 Si (Zorkivska) to 921 x 10-5 Si (Borkivska) for argillites; from 7 x 10-5 Si (Nizhynska) to 11450 x 10-5 Si (Borkivska) for aleurolites; from 3,9 x 10-5 Si to 207 x 10-5 Si for limestones; about 0 (Zorkivska) for anhydrite; from 1,7 x 10-5 Si (Guzhivska) to 11666 x 10-5 Si (Borkivska) for sandstones. Tuff breccias are characterized by χ of only 13 x 10-5 Si and 80 x 10-5 Si. Magnetic susceptibility of basalt is high enough - 11110 x 10-5 Si. Low values of magnetic susceptibility characterize gneisses (from 17 x 10-5 Si to 51 x 10-5 Si) and granite-gneiss (about 41 x 10-5 Si). The temperature influence on magnetic susceptibility of the rocks was researched. We made a pair from each sample for laboratory experiments. One of them was saturated by gasoline during 1 month the other remained dry. Samples magnetic susceptibility in dependence on temperature with the purpose of accelerating any processes taking place in them was measured. Step of heating was 50 deg C (from 100 deg C to 350 deg C). Magnetic susceptibility was measured on the astatic magnetometer and on the magnetic susceptibility bridge. As a result graphs of absolute values of magnetic susceptibility in dependence on the temperature were received. After experiment we can confirm that only in a small number of gasoline-saturated samples magnetic susceptibility increase (argillites

  6. Intercomparison of reactive transport models applied to degradation of a concrete / clay interface

    International Nuclear Information System (INIS)

    Full text of publication follows: Assuming a future disposal of spent nuclear fuel in deep geologic formation of Callovian- Oxfordian argillite in France, concrete will be used extensively to construct the disposal chambers in the host formation, and also as radioactive waste containment material. After being sealed, the repository will become saturated with interstitial waters from the Callovian-Oxfordian argillite, which will produce high pH solutions through interaction with the concrete. The aggressiveness of these alkaline solutions may weaken the clay's confinement properties (bentonite and argillite) with respect to long-lived radionuclides by change of the mineralogy. Conversely, the clayey formation with a high partial pressure of CO2 represents an aggressive media for the concrete. The hydrogeological and chemical reactions of deep-underground systems are therefore intimately coupled and reactive transport models are increasingly used for performance assessment of nuclear waste disposal [1]. The main objective of this study is to present an intercomparison study using different reactive transport codes, where among PHREEQC1D [2], PHAST [3] and TOUGHREACT [4] applied to determine, in space and time, the extension of the alkaline perturbation and the associated degradation of concrete. The calculations were carried out after the definition of a complete mineralogy for both media. The experimental work made in the European Ecoclay II project [5] allowed a selection of reaction paths and of new phases for the thermodynamic database. Calculations were carried out over a simulated period of 100,000 years at different temperatures. Results of the different codes are compared and discussed. [1] De Windt L., Burnol A., Montarnal P., Van Der Lee.J., (2003) Intercomparison of reactive transport models applied to UO2 oxidative dissolution and uranium migration., Journal of Contaminant Hydrology, 61, 1-4, 303-312; [2] Parkhurst D.L., Appelo C.A.J. (1999) - User

  7. Deformation and damage modes of deep argillaceous rocks under hydro-mechanical stresses

    International Nuclear Information System (INIS)

    An experimental identification of the hydro-mechanical behaviour of an argillite rock is proposed within a multi-scale approach. In particular, interest is focused on the spatial and temporal localization of strain and damage in a specimen during hydro-mechanical loading. Firstly, we describe the techniques used to follow the rock evolutions under loading, and in particular Digital Images Correlation (DIC), Acoustic Emission, microscopy and mercury intrusion porosimetry. Measurement errors and device limitations are discussed. The studied material is the Callovo-Oxfordian indurated argillaceous rock (or argillite) of the Bure site where ANDRA has built an underground research laboratory to study the radioactive waste storage. Petrophysical characterizations and microstructural observations by optical and scanning electron microscopy provide an identification of the constitutive phase and a characterization of their spatial distribution and typical sizes. Argillite can be described as a composite structure with a continuous clay matrix and embedded mineral particles, essentially quartz and carbonates. The typical size of these particles ranges from a few micrometers to a few hundreds micrometers, with an average close to 50 μ.m. The general experimental procedure combines two steps: in a fist time, imposed suctions bring samples to a given degree of water saturation, and, in a second time, uniaxial mechanical compression tests are performed. To understand the evolutions of the material under hydric and mechanical loading, samples are instrumented with standard measurement techniques, but also with Digital Image Correlation, at both the global scale of the sample and the local scale of the composite microstructure, and with Acoustic Emissions recording. Moisture transfers are imposed by controlled suctions on the range of 150 to 2.8 MPa, corresponding to the relative humidity range of 32 to 98%RH. During pure hydric solicitation, the changes in physical parameters

  8. The impact of the earthquake cycle on fluid flow through fractures in argillaceous formations

    International Nuclear Information System (INIS)

    Employing empirical observations of the hydrological changes that follow major earthquakes it becomes possible to predict subsurface fluid-flows that accompany active tectonics. Levels of co-seismic strain and the consequential hydrogeological changes, are largest close to jogs in the plane of fault-rupture. Low permeability argillaceous formations may be either passively or actively affected by the hydrogeological changes that accompany co-seismic strain-cycling. Fluid release is associated with consolidation of the sediment at greater depth, as well as with co-seismic strain, and this in turn can generate intra-formational faulting or the remobilization of the argillite and the eruption of mud volcanoes, sometimes explosively. In areas of active tectonics, intermittent hydraulic activity along fractures may be a feature of low permeability sedimentary formations overlying confined aquifers. (author)

  9. The Callovo-Oxfordian of the Paris Basin: From its geological context to the modelling of its properties

    International Nuclear Information System (INIS)

    The French law from December 30, 1991 entrusted the French national agency for radioactive wastes (ANDRA) with the mission of assessing the feasibility of a deep geological repository in the clay-rich Callovo-Oxfordian formation of NE France (Meuse and Haute-Marne departements). A research program, coordinated by ANDRA and involving several university laboratories and other French organizations (CNRS, CEA, BRGM, INERIS, INPL, ENSMP) has permitted to gather a huge amount of information about the properties of the Callovo-Oxfordian formation of the eastern part of the Paris basin. These properties are summarized in this introductive paper: paleo-geography, bio-stratigraphy of ammonites, clay mineralogy and other minerals content, anisotropy of argillite beds, permeability and porosity, osmosis and thermal diffusion, chemistry of interstitial waters, fracturing.. (J.S.)

  10. Peralkaline- and calc-alkaline-hosted volcanogenic massive sulfide deposits of the Bonnifield District, East-Central Alaska

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Foley, Nora K.; Slack, John E.; Koenig, Alan E.; Oscarson, Robert L.

    2012-01-01

    Volcanogenic massive sulfide (VMS) Zn-Pb-Cu-Ag-Au deposits of the Bonnifield mining district formed during Late Devonian-Early Mississippian magmatism along the western edge of Laurentia. The largest deposits, Dry Creek and WTF, have a combined resource of 5.7 million tonnes at 10% Zn, 4% Pb, 0.3% Cu, 300 grams per tonne (g/t) Ag, and 1.6 g/t Au. These polymetallic deposits are hosted in high field strength element (HFSE)- and rare-earth element (REE)-rich peralkaline (pantelleritic) metarhyolite, and interlayered pyritic argillite and mudstone of the Mystic Creek Member of the Totatlanika Schist Formation. Mystic Creek metarhyolite and alkali basalt (Chute Creek Member) constitute a bimodal pair that formed in an extensional environment. A synvolcanic peralkaline quartz porphyry containing veins of fluorite, sphalerite, pyrite, and quartz intrudes the central footwall at Dry Creek. The Anderson Mountain deposit, located ~32 km to the southwest, occurs within calc-alkaline felsic to intermediate-composition metavolcanic rocks and associated graphitic argillite of the Wood River assemblage. Felsic metavolcanic rocks there have only slightly elevated HFSEs and REEs. The association of abundant graphitic and siliceous argillite with the felsic volcanic rocks together with low Cu contents in the Bonnifield deposits suggests classification as a siliciclastic-felsic type of VMS deposit. Bonnifield massive sulfides and host rocks were metamorphosed and deformed under greenschist-facies conditions in the Mesozoic. Primary depositional textures, generally uncommon, consist of framboids, framboidal aggregates, and spongy masses of pyrite. Sphalerite, the predominant base metal sulfide, encloses early pyrite framboids. Galena and chalcopyrite accompanied early pyrite formation but primarily formed late in the paragenetic sequence. Silver-rich tetrahedrite is a minor late phase at the Dry Creek deposit. Gold and Ag are present in low to moderate amounts in pyrite from all of

  11. Technological demonstrators. Researches and studies on the storage and disposal of long living intermediate level and high level radioactive wastes

    International Nuclear Information System (INIS)

    This brochure presents the technological demonstrators made by the French national agency of radioactive wastes (ANDRA) and exhibited at Limay (Yvelines, France). These demonstrators, built at scale 1, have been an essential support to the establishment of the 'Dossier 2005' which demonstrates the feasibility of a reversible disposal of long living-intermediate level and high level radioactive wastes in the Callovo-Oxfordian argillite of Meuse-Haute Marne. Two type of demonstrators were built: demonstrators of storage containers for long living-intermediate level wastes and for spent fuels, and dynamic demonstrators for containers handling. This brochure presents these different demonstrators, their characteristics and the results of their tests. (J.S.)

  12. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation

    International Nuclear Information System (INIS)

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  13. Modeling of thermal evolution of near field area around single pit mode nuclear waste canister disposal in soft rocks

    International Nuclear Information System (INIS)

    Soft rocks like argillites/shales are under consideration worldwide as host rock for geological disposal of vitrified as well as spent fuel nuclear waste. The near field around disposed waste canister at 400-500m depth witnesses a complex heat field evolution due to varying thermal characteristics of rocks, coupling with hydraulic processes and varying intensity of heat flux from the canister. Smooth heat dissipation across the rock is desirable to avoid buildup of temperature beyond design limit (100 °C) and resultant micro fracturing due to thermal stresses in the rocks and intervening buffer clay layers. This also causes enhancement of hydraulic conductivity of the rocks, radionuclide transport and greater groundwater ingress towards the canister. Hence heat evolution modeling constitutes an important part of safety assessment of geological disposal facilities

  14. Laboratory studies of radionuclide distributions between selected groundwaters and geologic media. Progress report, January 1--March 31, 1979

    International Nuclear Information System (INIS)

    The Los Alamos Scientific Laboratory contribution to the Waste Isolation Safety Assessment Program, Task 4, for the second quarter of FY-79 involved plutonium, americium, and uranium (VI) batch sorption studies on argillite, is presented. The behavior of plutonium and americium in aqueous solutions at pH approx. = 8 with respect to container sorption, filtering, and centrifuging was also investigated. Studies of the variability of the sorption behavior for tuff were completed. Migration rate studies on crushed and fractured materials were initiated. The development of the systems for performing controlled atmosphere measurements has been completed. Additional chemical analysis has been performed, as were some studies related to microautoradiography. Additional cation exchange capacity and ethylene glycol surface area measurements have also been made

  15. Development of a reactive transport code MC-CEMENT Ver.2 and its verification using 15-year in-situ concrete/clay interactions at the Tournemire URL

    International Nuclear Information System (INIS)

    Tournemire Underground Research Laboratory (Aveyron, France) has been characterized by IRSN. Mineralogical and chemical evolution and spatial distribution of porosity were analyzed. Precipitation of gypsum, recrystallization of mixed-layer clays, K-feldspars overgrowth etc. were observed. These mineralogical changes were limited within one cm in thickness. Clogging of the porosity was observed in the argillite while the porosity increased in the concrete. Our code was applied to the mineralogical evolution at the concrete/argillite interface. The calculation reproduced the observations such as the mineralogical changes limited within one cm in thickness, formation of CaCO3 and CSH, dissolution of quartz, decrease of porosity in argillite and increase in concrete. These agreements indicate possibility that the models based on lab scale (∼ 1 y) experiments can be applied to longer time scale. The agreement in the evolution of the porosity may be adventitious because our previous calculation showed reverse evolution, increase of porosity in argillite and decrease in concrete. The fact that the calculation did not reproduce the dissolution of clays and the formation of gypsum indicates that there is still room for improvement in our model. (authors)

  16. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation; Phenomenes de transport couples dans les argiles du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Paszkuta, M

    2005-06-15

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  17. Technological demonstrators. Researches and studies on the storage and disposal of long living intermediate level and high level radioactive wastes; Les demonstrateurs technologiques. Recherches et etudes sur le stockage et l'entreposage des dechets de haute activite et de moyenne activite a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    This brochure presents the technological demonstrators made by the French national agency of radioactive wastes (ANDRA) and exhibited at Limay (Yvelines, France). These demonstrators, built at scale 1, have been an essential support to the establishment of the 'Dossier 2005' which demonstrates the feasibility of a reversible disposal of long living-intermediate level and high level radioactive wastes in the Callovo-Oxfordian argillite of Meuse-Haute Marne. Two type of demonstrators were built: demonstrators of storage containers for long living-intermediate level wastes and for spent fuels, and dynamic demonstrators for containers handling. This brochure presents these different demonstrators, their characteristics and the results of their tests. (J.S.)

  18. Redox reactions induced by hydrogen in deep geological nuclear waste disposal

    International Nuclear Information System (INIS)

    The aim of this study is to evaluate the abiotic hydrogen reactivity in deep geological nuclear waste storage. One crucial research interest concerns the role of H2 as a reducing agent for the aqueous/mineral oxidised species present in the site. Preliminary batch experiments carried out with Callovo-Oxfordian argillite, synthetic pore water and H2 gas lead to an important H2S production, in only few hours at 250 C to few months at 90 C. In order to explore whether H2S can originate from sulphate or pyrite (few percents of the argillite) reduction we performed dedicated experiments. Sulphate reduction experimented in di-phasic systems (water+gas) at 250-300 C and under 4 to 16 bar H2 partial pressure exhibits a high activation energy (131 kJ/mol) and requires H2S initiation and low pH condition as already observed in other published TSR experiments. The corresponding half-life is 210,000 yr at 90 C (thermal peak of the site). On the contrary, pyrite reduction into pyrrhotite by H2 occurs in few days at temperature as low as 90 C at pH buffered by calcite. The rate of the reaction could be described by a diffusion-like rate law in the 90-180 C temperature interval. The obtained results suggest that pyrite reduction is a process controlled both by the H2 diffusion across the pyrrhotite pits increasing during reaction progress and the reductive dissolution of pyrite. These new kinetics data can be applied in computation modelling, to evaluate the degree and extent of gas pressure buildup by taking into account the H2 reactive geochemistry. (author)

  19. Contribution of natural tracers for understanding transfers through argillaceous formations

    International Nuclear Information System (INIS)

    This study is part of a research programme conducted by IRSN on the safety of deep geological disposal of high level and intermediate long-lived radioactive wastes. It more especially concerns the geological medium considered as a full component of the multi-barrier concept proposed by Andra for a deep repository. Indeed, the Callovo-Oxfordian argillite of the Paris Basin, in the east of France, is being investigated by Andra as a potential host rock for this repository. Performance assessment of this natural barrier is based on the knowledge of its confinement properties and therefore on phenomena possibly involved in the mass transport of radionuclides. In this context, this work aimed at studying the distribution of tracers naturally present in pore waters obtained from boreholes having crossed Mesozoic sedimentary series involving impervious and compacted clay rocks in the East (Andra borehole, EST433) and south of France (IRSN boreholes). Radial diffusion and vapour exchange methods were used to calculate the concentrations and diffusion parameters of the studied tracers. In Tournemire formations, the different profiles describe a curved shapes attributed to a diffusive exchange between the argillite pore water and the surrounding aquifers. Concerning the Mesozoic formations crossed by EST433, the study of the different profiles confirms the diffusion as the dominant transport mechanism in the Callovo-Oxfordian formation, and permits identifying the transport processes in the whole studied column from the Oxfordian formations down to the Liassic one. This study also helps to identify the Liassic formations as a major source of salinity of the Dogger aquifer

  20. Paleomagnetism and anisotropy of magnetic susceptibility of the sedimentary cover in thrust units compared with tectonic strain. The Nice and Castellane arcs, SE France

    International Nuclear Information System (INIS)

    Complete text of publication follows. In the SE France, the arcs of Castellane and Nice developed during the Cenozoic as fold-and-thrust belts in a thick sedimentary cover of Mesozoic-Cenozoic age. They represent the most external foreland thrust units of the Alps. As geological mapping and remote sensing observation show, these arcs exhibit a remarkable curvature of about 90 deg, with in both cases a west-verging, N-S trending branch to the west and a south-verging, E-W trending branch to the south. Below the sedimentary cover, the pre-Mesozoic basement is poorly affected by the fold-and-thrust deformation. This structural pattern is commonly explained by the compressive folding of the cover above a major decollement in Triassic layers, as a result of two major tectonic events with E-W compression first and N-S compression second. A crucial problem is: how did these arcs develop? As previous paleomagnetic studies in this area were few results have been obtained (mainly in the Callovian-Oxfordian black shales of the N-S branch of the Castellane arc and the Permian argillite of the Barrot dome in the E-W branch of the same arc). Although suitable layers are few and remanent magnetization is usually very weak in the sedimentary cover of these arcs, we intend to carry out a more systematic paleomagnetic study (paleo-rotations and anisotropy of magnetic susceptibility AMS) associated with structural observations (especially palaeostress reconstruction based on inversion of brittle data). The paleomagnetic difficulties related to rock nature require a preliminary analysis of rock magnetization in the Eocene, Cretaceous, Jurassic argillites and shales in these areas, which is in progress. The AMS will allow comparison between paleostress orientations (reconstructed from brittle tectonic analysis) and the main structural directions (from geological mapping). The ultimate purpose of this study is to provide a consistent model of structural and kinematic development of

  1. Redox reactions induced by hydrogen in deep geological nuclear waste disposal; Transformations mineralogiques et geochimiques induites par la presence d'hydrogene dans un site de stockage de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Truche, L.

    2009-10-15

    The aim of this study is to evaluate the abiotic hydrogen reactivity in deep geological nuclear waste storage. One crucial research interest concerns the role of H{sub 2} as a reducing agent for the aqueous/mineral oxidised species present in the site. Preliminary batch experiments carried out with Callovo-Oxfordian argillite, synthetic pore water and H{sub 2} gas lead to an important H{sub 2}S production, in only few hours at 250 C to few months at 90 C. In order to explore whether H{sub 2}S can originate from sulphate or pyrite (few percents of the argillite) reduction we performed dedicated experiments. Sulphate reduction experimented in di-phasic systems (water+gas) at 250-300 C and under 4 to 16 bar H{sub 2} partial pressure exhibits a high activation energy (131 kJ/mol) and requires H{sub 2}S initiation and low pH condition as already observed in other published TSR experiments. The corresponding half-life is 210,000 yr at 90 C (thermal peak of the site). On the contrary, pyrite reduction into pyrrhotite by H{sub 2} occurs in few days at temperature as low as 90 C at pH buffered by calcite. The rate of the reaction could be described by a diffusion-like rate law in the 90-180 C temperature interval. The obtained results suggest that pyrite reduction is a process controlled both by the H{sub 2} diffusion across the pyrrhotite pits increasing during reaction progress and the reductive dissolution of pyrite. These new kinetics data can be applied in computation modelling, to evaluate the degree and extent of gas pressure buildup by taking into account the H{sub 2} reactive geochemistry. (author)

  2. Experimental characterization of the hydro-mechanical behaviour of Meuse/Haute-Marne argilites; Caracterisation experimentale du comportement hydromecanique des argilites de Meuse/Haute-Marne

    Energy Technology Data Exchange (ETDEWEB)

    Escoffier, S

    2002-04-01

    Within the framework of a feasibility study of underground radioactive waste repository the experimental characterization of the coupled behavior of the host layer is of first importance. This work concerns the experimental characterization in laboratory of the poro-elastic behavior of argillite which constitutes the host layer of the future underground laboratory of ANDRA located at the limit of the Meuse/Haute-Marne. The theoretical approach is the Mechanics of Porous Media defined by Coussy [1991] which has the advantage of providing a formulation of the behavior laws using measurable parameters in laboratory. The difficulties or the feasibility of the characterization tests of these rocks coupled behavior are related to their very low permeability which requires an adaptation of the experimental devices initially used on more permeable rocks. Initially a synthesis on the knowledge of the poro-elastic parameters of Meuse/Haute-Marne argillite is given. Thereafter a first approach of the use of the studies of sensitivity as tools of decision-making aid is proposed. The experimental difficulties encountered by the various experimenters are illustrated by the diversity of the experimental choices, the test duration or by the results disparity. Because of economic, political and ecological stake, the studies of sensitivity could make it possible to direct the experimental efforts by giving indications on the dominating parameters in the coupled behavior of a rock. In the second time after the presentation of the test results of physical characterization 3 types of tests are described: permeability test (pulse test), determination of Biot coefficient under odometric loading and isotropic drained test. The complexity of these tests is related to the attack of the experimental limits. They are presented in detail: theoretical recalls, experimental set up, experimental protocol, unfolding and test results. (author)

  3. Preliminary assessment of shales and other argillaceous rocks in the United States

    International Nuclear Information System (INIS)

    Shales and related clay-rich rock types throughout the conterminous United States are geologically characterized and evaluated on a regional basis relative to their promise as possible candidate rock sequences for the repository disposal of high-level radioactive wastes. Only stratigraphic intervals or parts of them that are laterally persistent, consist of 75 m or more of shale, mudstone, or argillite, and lie at depths of 305 to 915 m below the land surface are included. The general properties of clay-rich rocks, as well as the several desirable characteristics that make them potentially attractive as disposal host candidates, are reviewed. Also discussed are the geologic factors that dictate the potential acceptability of any shale sequence relative to the regional subsurface distribution of units that meet the basic criteria of extent, thickness, and depth. Included in this context are the tectonic setting, geologic structure, seismicity, groundwater hydrology, mineralogy and content of organic matter, mineral resource potential of both the shales and the enclosing geologic basins, and any construction experience on underground openings, such as hydrocarbon-storage facilities. The clay-rich strata that appear to be promising on the basis of this evaluation are inventoried according to their occurrence and distribution within nine geologic-geomorphic regions throughout the country. Also considered are several, more localized occurrences of Precambrian argillites whose mineralogies make them a related yet separate group in comparison with the sedimentary strata already summarized. Topics for which data are insufficient or on which inadequate study has been conducted to date are also identified

  4. Experimental characterization of the hydro-mechanical behaviour of Meuse/Haute-Marne argilites

    International Nuclear Information System (INIS)

    Within the framework of a feasibility study of underground radioactive waste repository the experimental characterization of the coupled behavior of the host layer is of first importance. This work concerns the experimental characterization in laboratory of the poro-elastic behavior of argillite which constitutes the host layer of the future underground laboratory of ANDRA located at the limit of the Meuse/Haute-Marne. The theoretical approach is the Mechanics of Porous Media defined by Coussy [1991] which has the advantage of providing a formulation of the behavior laws using measurable parameters in laboratory. The difficulties or the feasibility of the characterization tests of these rocks coupled behavior are related to their very low permeability which requires an adaptation of the experimental devices initially used on more permeable rocks. Initially a synthesis on the knowledge of the poro-elastic parameters of Meuse/Haute-Marne argillite is given. Thereafter a first approach of the use of the studies of sensitivity as tools of decision-making aid is proposed. The experimental difficulties encountered by the various experimenters are illustrated by the diversity of the experimental choices, the test duration or by the results disparity. Because of economic, political and ecological stake, the studies of sensitivity could make it possible to direct the experimental efforts by giving indications on the dominating parameters in the coupled behavior of a rock. In the second time after the presentation of the test results of physical characterization 3 types of tests are described: permeability test (pulse test), determination of Biot coefficient under odometric loading and isotropic drained test. The complexity of these tests is related to the attack of the experimental limits. They are presented in detail: theoretical recalls, experimental set up, experimental protocol, unfolding and test results. (author)

  5. Iodine and selenium migration through argillaceous rocks

    International Nuclear Information System (INIS)

    Deep argillaceous formations are considered as potential host rock for high-level radioactive waste repository. Based on safety assessment calculations, active selenium (79Se) and iodine (129I) from high level radioactive waste might be ones of the major dose contributors due to their longevity and their anionic character. However, because of their high sensitivity to redox condition, a special attention to the oxidation state of these elements is required. A comparative study on the diffusion properties of selenium and iodine through argillaceous rocks was realized with the aim to determine the effects of both the redox conditions and the mineralogy on the migration of these two elements. For these purposes, we have studied two argillaceous rocks: Toarcian argillite from Tournemire (France) and Opalinus clay (OPA) from the Mont-Terri (Switzerland). The study of the iodide migration allowed to confirm the control on the iodide retention of both oxidized pyrite and natural organic matter. A kinetic control of the iodide sorption is also suspected. We focus the selenium study on the more oxidized species, Se(IV) and Se(VI). The Se(IV) migration is strongly dependant from oxido-reduction processes. Indeed, the Se(IV) diffusion experiments through Tournemire argillite and OPA indicated a significant reduction associated to Fe(II). The Se(VI) study evidenced a behavior dependant from the initial concentration: at the highest concentration, no significant retention was observed while the retention is significant at the lowest concentration. Furthermore, spectroscopic analyses tend to show a low Se(VI) reduction at the Fe contact. However, biotic origin cannot be excluded. (author)

  6. Laboratory studies of radionuclide distributions between selected groundwaters and geologic media. Progress report, October 1, 1979-September 30, 1980

    International Nuclear Information System (INIS)

    During FY-1980, Los Alamos Scientific Laboratory contributions to the Waste/Rock Interactions Technology program were primarily in the areas of migration-rate studies using crushed rock, whole core, and fractured core columns; parametric studies of variables which may influence radionuclide sorption-desorption behavior; and initial studies of actinide chemistry in near-neutral solutions and Eh control. Batch experiments in both air and a controlled atmosphere (nitrogen, less than or equal to 0.2 ppM oxygen, less than or equal to 20 ppM carbon dioxide) for the sorption of several radionuclides on granite and argillite were completed. These data also provided informaton on the effects of other parameters, such as particle size and contact time. All nine elements studied had different sorption ratios for argillite when measured under the controlled atmosphere than when measured in air, except possibly for americium where any effect was smaller than the standard deviations. As expected, strontium, cesium, and barium are least affected by the presence or absence of oxygen and carbon dioxide. Columns of crushed rock and solid and cracked cores were used to study the migration of radionuclides through such materials. In general, sorption ratios measured by batch techniques are 2 to 3 times greater than those for columns; however, a wide variation in behavior was observed, depending upon the element and the mineralogy. Work has begun on a system wherein traced groundwater is circulated through a crushed rock column; this should provide a link between the usual, single-pass, crushed rock columns and the batch experiments. Materials characterization has continued, and techniques for the determination of Fe(II) in silicate rocks and groundwater have been made operational. Work on the fundamental solution chemistry of the actinides has been started

  7. Experimental simulation of the geological storage of CO2: particular study of the interfaces between well cement, cap-rock and reservoir rock

    International Nuclear Information System (INIS)

    The geological storage of the CO2 is envisaged to mitigate the anthropogenic greenhouse gas emissions in the short term. CO2 is trapped from big emitters and is directly injected into a reservoir rock (mainly in deep salty aquifers, depleted hydrocarbon oil fields or unexploited charcoal lodes) located at more than 800 m deep. In the framework of the CO2 storage, it is crucial to ensure the integrity of the solicited materials in order to guarantee the permanent confinement of the sequestrated fluids. Using experimental simulation the purpose of this work is to study the mechanisms which could be responsible for the system destabilization and could lead CO2 leakage from the injection well. The experimental simulations are performed under pressure and temperature conditions of the geological storage (100 bar and from 80 to 100 deg. C). The first experimental model, called COTAGES (for 'Colonne Thermoregulee A Grains pour Gaz a Effet de Serre') allows studying the effects of the thermal destabilisation caused by the injection of a fluid at 25 deg. C in a hotter reservoir (submitted to the geothermal gradient). This device composed of an aqueous saline solution (4 g.L-1 of NaCl), crushed rock (Lavoux limestone or Callovo-Oxfordian argillite) and gas (N2 or CO2) allows demonstrating an important matter transfer from the cold area (30 deg. C) toward the hot area (100 deg. C). The observed dissolution/precipitation phenomena leading to changes of the petro-physical rocks properties occur in presence of N2 or CO2 but are significantly amplified by the presence of CO2. Concerning the experiments carried out with Lavoux limestone, the dissolution in the cold zone causes a raise of porosity of about 2% (initial porosity of 8%) due to the formation of about 500 pores/mm2 with a size ranging between 10 and 100 μm2. The precipitation in the hot zone forms a micro-calcite fringe on the external part of the grains and fills the intergrain porosity. Concerning the

  8. Evidence of discontinuous and continuous gas migration through undisturbed and self-sealed Cox clay-stone

    International Nuclear Information System (INIS)

    it is a long-lasting procedure, it allows to assess both gas migration modes at the sample outlet (i.e. discontinuous or continuous). In our laboratory, by using the step-by-step method under in situ confining stresses (5 to 12 MPa), and argon as gas, former studies have mainly investigated discontinuous gas passage for vertical, horizontal or inclined cores from the Bure site. A number of samples was self-sealed, mainly those from horizontal or inclined cores. Variations by one order of magnitude have been recorded between results on horizontal and inclined cores or vertical cores. While GBP values range from 1.26 MPa and up to 3 MPa for the first test series on vertical cores, it is almost an order of magnitude lower for the second test series (horizontal or inclined cores), with values ranging from 0.2 to 1.3 MPa. This difference is mainly associated to gas passage through self-sealed fractures, in relation with clay transverse anisotropy. Indeed, COx clay-stone is a sedimentary indurated clay, composed of sub-horizontal diagenetic bedding planes: whenever GBP tests are performed along the bedding planes, lower values may be expected (due to a greater number of sealed cracks, created during sample preparation) rather than when performing GBP experiments perpendicularly to the bedding planes. Despite this extensive research, which was backed by numerical simulations of homogeneous media with LML and EDF-ASTER codes, several scientific questions remain. In particular, argillite self-sealing or undisturbed states may display different gas migration properties: it is expected that undisturbed matter will let gas pass at higher pressure than if self-sealed. Also, the discontinuous gas migration mode may be related to diffusion or capillary snap off, or to both phenomena. And discontinuous breakthrough does not suffice to describe fully the gas migration phenomena through undisturbed or self-sealed argillite, for it occurs distinctly from continuous passage and gas

  9. Viscoplastic behaviour including damage for deep argillaceous rocks: from in situ observations to constitutives equations

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In order to demonstrate the feasibility of a radioactive waste repository in clay-stone formation, French national radioactive waste management agency (ANDRA) started in 2000 to build an underground research laboratory CMHM) at Bure located at nearly 300 km East of Paris. The host formation consists of a clay-stone (Callovo-Oxfordian argillites) and lies between 430 m and 550 m deep. On the basis of numerous campaigns of laboratory tests (uniaxial/triaxial, mono/multi stage creep and relaxation) undertaken for characterizing mechanical and hydro-mechanical short-term or long-term behaviour of these argillites, several constitutive models were developed in the framework of MODEXREP European project and scientific cooperation between ANDRA and national institutions. Moreover, more than 400 m horizontal galleries at the main level of -490 m at CMHM laboratory have been instrumented since April 2005 with the aim to understand the rock behaviour (especially the long term behaviour) needed for the repository design. The continuous measurements of convergencies of the galleries are available contributing to better understand the time-dependent response of the argillites at natural scale. Analysis of convergence data over a period of 2 years leads to the following conclusions: (a) viscoplastic strains are anisotropic and depend on the gallery orientation with regard to the initial stress anisotropy in the investigated formation; (b) the viscoplastic strain rates observed in the undamaged area far from the galleries walls are in the same order of magnitude as those obtained on samples, whereas those recorded in the damaged or fractured zone near to the walls are one to two orders of magnitude higher; indicating the damage and created macroscopic fractures influences on the viscoplastic strains. This influence has not been taken into account in the previous constitutive models. From these observations, a macroscopic

  10. ASTER spectral analysis and lithologic mapping of the Khanneshin carbonatite volcano, Afghanistan

    Science.gov (United States)

    Mars, J.C.; Rowan, L.C.

    2011-01-01

    Advanced Spaceborne Thermal and Reflection Radiometer (ASTER) data of the early Quaternary Khanneshin carbonatite volcano located in southern Afghanistan were used to identify carbonate rocks within the volcano and to distinguish them from Neogene ferruginous polymict sandstone and argillite. The carbonatitic rocks are characterized by diagnostic CO3 absorption near 11.2 ??m and 2.31-2.33 ??m, whereas the sandstone, argillite, and adjacent alluvial deposits exhibit intense Si-O absorption near 8.7 ??m caused mainly by quartz and Al-OH absorption near 2.20 ??m due to muscovite and illite. Calcitic carbonatite was distinguished from ankeritic carbonatite in the short wave infrared (SWIR) region of the ASTER data due to a slight shift of the CO3 absorption feature toward 2.26 ??m (ASTER band 7) in the ankeritic carbonatite spectra. Spectral assessment using ASTER SWIR data suggests that the area is covered by extensive carbonatite flows that contain calcite, ankerite, and muscovite, though some areas mapped as ankeritic carbonatite on a pre existing geologic map were not identified in the ASTER data. A contact aureole shown on the geologic map was defined using an ASTER false color composite image (R = 6, G = 3, B = 1) and a logical operator byte image. The contact aureole rocks exhibit Fe2+, Al-OH, and Fe, Mg-OH spectral absorption features at 1.65, 2.2, and 2.33 ??m, respectively, which suggest that the contact aureole rocks contain musco vite, epidote, and chlorite. The contact aureole rocks were mapped using an Interactive Data Language (IDL) logical operator. A visible through short wave infrared (VNIR-SWIR) mineral and rock-type map based on matched filter, band ratio, and logical operator analysis illustrates: (1) laterally extensive calcitic carbonatite that covers most of the crater and areas northeast of the crater; (2) ankeritic carbonatite located southeast and north of the crater and some small deposits located within the crater; (3) agglomerate that

  11. Hydro-mechanical processes

    International Nuclear Information System (INIS)

    This session gathers 13 articles dealing with: three-dimensional and time stepping modelling of the whole Meuse/Haute-Marne ANDRA URL (F. Laouafa, J.B. Kazmierczak, G. Armand, J. Vaunat, M. Jobmann, M. Polster); a constitutive model for a deep argillaceous rock using Hoek-Brown criteria (K. Su, C. Chavant, M. Souley); the long term behaviour of the Boom clay: influence of viscosity on the pore pressure distribution (C. Coll, R. Charlier, X.L. Li, F. Collin); the microstructural changes induced by viscoplastic deformations in argillaceous rocks (F.L. Pellet, G. Fabre, K. Su, P. Lebon); the engineered barrier experiment at Mont Terri rock laboratory (J.L. Garcia-Sineriz, M. Rey, J.C. Mayor); the chemical influence on the Hydro-Mechanical behaviour of high-density FEBEX bentonite (E. Castellanos, M.V. Villar, E. Romero, A. Lloret, A. Gens); the influence of water exchanges on the gallery convergence (P. Gerard, R. Charlier, R. Chambon, F. Collin); a new method for ageing resistant storage of argillaceous rock samples to achieve reproducible experimental results even after long intermediate storage times (O. Czaikowski, K.H. Lux); the installation and evaluation of a large-scale in-situ shaft seal experiment in Boom clay the RESEAL project M. Van Geet, W. Bastiaens, G. Volckaert, E. Weetjens, X. Sillen, A. Gens, M.V. Villar, Ch. Imbert, M. Filippi, F. Plas); the hydro-Mechanical response of the Callovo-Oxfordian mud-stone around a deep vertical drift (J. Vaunat, B. Garitte, A. Gens, K. Su, G. Armand); the sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite (J.F. Harrington, D.J. Birchall, P. Sellin); the comparison of the poro-elastic behavior of Meuse/Haute Marne and Tournemire argillites: effect of loading and saturation states (E. Bemer, A. Noiret, F. Homand, A. Rejeb); and the multi-scale modelling of the argillites mechanical behaviour (A. Abou-Chakra Guery, F. Cormery, K. Su, J.F. Shao, D. Kondo)

  12. Hydro-mechanical processes

    Energy Technology Data Exchange (ETDEWEB)

    Laouafa, F.; Kazmierczak, J.B. [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique ALATA, 60 - Verneuil en Halatte (France); Armand, G. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Vaunat, J. [Catalonia UPC- Technical Univ., Barcelona (Spain); Jobmann, M.; Polster, M. [DBETEC- DBE Technology GmbH, Peine (Germany); Su, K.; Lebon, P.; Plas, F.; Armand, G.; Abou-Chakra Guery, A.; Cormery, F.; Shao, J.F.; Kondo, D. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Souley, M. [Institut National de l' Environnement Industriel et des Risques (INERIS), 54 - Nancy (France); Coll, C.; Charlier, R.; Collin, F.; Gerard, P. [Liege Univ., Dept. ArGEnCo (Belgium); Xiang Ling, Li [ESV EURIDICE, SCK.CEN, Belgian Nuclear Research Centre, Mol (Belgium); Collin, F. [Liege Univ., Charge de Recherches FNRS (Belgium); Pellet, F.L.; Fabre, G. [University Joseph Fourier, Laboratory 3S-R, 38 - Grenoble (France); Garcia-Sineriz, J.L.; Rey, M. [AITEMIN - Asociacion para la Investigacion y Desarrollo Industrial de los Recursos Naturales, Madrid (Spain); Mayor, J.C. [ENRESA - Empresa Nacional des Residuos Radioactivos, Madrid (Spain); Castellanos, E.; Romero, E.; Lloret, A.; Gens, A. [Catalunya Univ. Politecnica, UPC (Spain); Villar, M.V. [CIEMAT - Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain); Chambon, R. [Laboratoire 3S, UJF-INPG-CNRS, 38 - Grenoble (France); Czaikowski, O.; Lux, K.H. [Clausthal Univ. of Technology, Professorship for Waste Disposal and Geomechanics, Clausthal-Zellerfeld (Germany); Van Geet, M.; Bastiaens, W.; Volckaert, G.; Weetjens, E.; Sillen, X. [SCK-CEN, Waste and Disposal dept., Mol (Belgium); ONDRAF/NIRAS, Brussel (Belgium); Imbert, Ch. [CEA Saclay, Dept. de Physico-Chimie (DPC/SCCME/LECBA), 91 - Gif sur Yvette (France)] [and others

    2007-07-01

    This session gathers 13 articles dealing with: three-dimensional and time stepping modelling of the whole Meuse/Haute-Marne ANDRA URL (F. Laouafa, J.B. Kazmierczak, G. Armand, J. Vaunat, M. Jobmann, M. Polster); a constitutive model for a deep argillaceous rock using Hoek-Brown criteria (K. Su, C. Chavant, M. Souley); the long term behaviour of the Boom clay: influence of viscosity on the pore pressure distribution (C. Coll, R. Charlier, X.L. Li, F. Collin); the microstructural changes induced by viscoplastic deformations in argillaceous rocks (F.L. Pellet, G. Fabre, K. Su, P. Lebon); the engineered barrier experiment at Mont Terri rock laboratory (J.L. Garcia-Sineriz, M. Rey, J.C. Mayor); the chemical influence on the Hydro-Mechanical behaviour of high-density FEBEX bentonite (E. Castellanos, M.V. Villar, E. Romero, A. Lloret, A. Gens); the influence of water exchanges on the gallery convergence (P. Gerard, R. Charlier, R. Chambon, F. Collin); a new method for ageing resistant storage of argillaceous rock samples to achieve reproducible experimental results even after long intermediate storage times (O. Czaikowski, K.H. Lux); the installation and evaluation of a large-scale in-situ shaft seal experiment in Boom clay the RESEAL project M. Van Geet, W. Bastiaens, G. Volckaert, E. Weetjens, X. Sillen, A. Gens, M.V. Villar, Ch. Imbert, M. Filippi, F. Plas); the hydro-Mechanical response of the Callovo-Oxfordian mud-stone around a deep vertical drift (J. Vaunat, B. Garitte, A. Gens, K. Su, G. Armand); the sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite (J.F. Harrington, D.J. Birchall, P. Sellin); the comparison of the poro-elastic behavior of Meuse/Haute Marne and Tournemire argillites: effect of loading and saturation states (E. Bemer, A. Noiret, F. Homand, A. Rejeb); and the multi-scale modelling of the argillites mechanical behaviour (A. Abou-Chakra Guery, F. Cormery, K. Su, J.F. Shao, D. Kondo)

  13. Chemical and isotopic analysis of hydrocarbon traces degassed out of Callovo-Oxfordian argilites from Bure (France): methodology and results

    International Nuclear Information System (INIS)

    -Oxfordian argillite formation, Bure, eastern Paris Basin, are reported here. GC-C-IRMS analysis was performed on samples of gas naturally released from water-saturated argillite cores stored in specifically-designed outgassing cells shortly after drilling. It was possible to quantify the concentrations and δ13C of methane, ethane and propane. (authors)

  14. Effect of desaturation and re-saturation on shale in underground galleries; Effets de la desaturation et de la resaturation sur l'argilite dans les ouvrages souterrains

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Q.T

    2006-03-15

    The aim of this thesis is to characterize by experimental and numerical approaches the hydric, mechanical and hydro-mechanical effects due to the desaturation and re-saturation of the Eastern argillite, host rock of the Bure site, future underground radioactive waste disposal facility. Experimental and numerical approaches for the characterization of hydric transfers in argilites are presented. A simple identification method is proposed which uses the determination of the linearized hydric diffusivity from weight measurements performed on samples (thin tubes and plates) submitted to humidity steps according to a desaturation-re-saturation cycle. The hydric transfer is nonlinear. In order to interpret this phenomenon, a non-linear numerical model is established which takes into account the physical phenomena (hydraulic conduction, vapor diffusion, phase change..). The evolution of the physical and mechanical behaviour of the argillaceous rock with respect to the imposed humidity is then analyzed according to a desaturation-re-saturation cycle by successive steps. The hydric deformation, the velocity of ultrasonic waves propagation, the elastic properties, the rupture characteristics and the delayed phenomena depend on the hydric state of the material. The desaturation and re-saturation influence on a scale model of tunnel is analyzed. Thick tubes parallel or perpendicular to the stratification are used to show up the anisotropy of the rock. These tubes are submitted to hydric loads by blowing air with variable hygrometry through their center hole. A nonlinear poro-elastic model is used to interpret the anisotropic hydro-mechanical phenomena observed. It is shown that hydric loads can lead to the rupture of test samples which follow the anisotropic directions of the rock and which can be interpreted by the hydro-mechanical model as a violation of a rupture criterion in total pulling stress. Finally, numerical calculations for the phenomena generated by desaturation

  15. Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

    Science.gov (United States)

    Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

    2016-03-01

    Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern

  16. Controls on accretion of flysch and melange belts at convergent margins: evidence from the Chugach Bay thrust and Iceworm melange, Chugach accretionary wedge, Alaska

    Science.gov (United States)

    Kusky, T.M.; Bradley, D.C.; Haeussler, P.J.; Karl, S.

    1997-01-01

    Controls on accretion of flysch and melange terranes at convergent margins are poorly understood. Southern Alaska's Chugach terrane forms the outboard accretionary margin of the Wrangellia composite terrane, and consists of two major lithotectonic units, including Triassic-Cretaceous melange of the McHugh Complex and Late Cretaceous flysch of the Valdez Group. The contact between the McHugh Complex and the Valdez Group on the Kenai Peninsula is a tectonic boundary between chaotically deformed melange of argillite, chert, greenstone, and graywacke of the McHugh Complex and a less chaotically deformed melange of argillite and graywacke of the Valdez Group. We assign the latter to a new, informal unit of formational rank, the Iceworm melange, and interpret it as a contractional fault zone (Chugach Bay thrust) along which the Valdez Group was emplaced beneath the McHugh Complex. The McHugh Complex had already been deformed and metamorphosed to prehnite-pumpellyite facies prior to formation of the Iceworm melange. The Chugach Bay thrust formed between 75 and 55 Ma, as shown by Campanian-Maastrichtian depositional ages of the Valdez Group, and fault-related fabrics in the Iceworm melange that are cut by Paleocene dikes. Motion along the Chugach Bay thrust thus followed Middle to Late Cretaceous collision (circa 90-100 Ma) of the Wrangellia composite terrane with North America. Collision related uplift and erosion of mountains in British Columbia formed a submarine fan on the Farallon plate, and we suggest that attempted subduction of this fan dramatically changed the subduction/accretion style within the Chugach accretionary wedge. We propose a model in which subduction of thinly sedimented plates concentrates shear strains in a narrow zone, generating melanges like the McHugh in accretionary complexes. Subduction of thickly sedimented plates allows wider distribution of shear strains to accommodate plate convergence, generating a more coherent accretionary style

  17. Tectonic controls on magmatism in the Geysers-Clear Lake region: Evidence from new geophysical models

    Science.gov (United States)

    Stanley, W.D.; Benz, H.M.; Walters, M.A.; Villasenor, A.; Rodriguez, B.D.

    1998-01-01

    In order to study magmatism and geothermal systems in The Geysers-Clear Lake region, we developed a detailed three-dimensional tomographic velocity model based on local earthquakes. This high-resolution model resolves the velocity structure of the crust in the region to depths of approximately 12 km. The most significant velocity contrasts in The Geysers-Clear Lake region occur in the steam production area, where high velocities are associated with a Quaternary granitic pluton, and in the Mount Hannah region, where low velocities occur in a 5-km-thick section of Mesozoic argillites. In addition, a more regional tomographic model was developed using traveltimes from earthquakes covering most of northern California. This regional model sampled the whole crust, but at a lower resolution than the local model. The regional model outlines low velocities at depths of 8-12 km in The Geysers-Clear Lake area, which extend eastward to the Coast Range thrust. These low velocities are inferred to be related to unmetamorphosed Mesozoic sedimentary rocks. In addition, the regional velocity model indicates high velocities in the lower crust beneath the Clear Lake volcanic field, which we interpret to be associated with mafic underplating. No large silicic magma chamber is noted in either the local or regional tomographic models. A three-dimensional gravity model also has been developed in the area of the tomographic imaging. Our gravity model demonstrates that all density contrasts can be accounted for in the upper 5-7 km of the crust. Two-dimensional magnetotelluric models of data from a regional, east-west profile indicate high resistivities associated with the granitic pluton in The Geysers production area and low resistivities in the low-velocity section of Mesozoic argillites near Mount Hannah. No indication of midcrustal magma bodies is present in the magnetotelluric data. On the basis of heat flow and geologic evidence, Holocene intrusive activity is thought to have

  18. Magmatic and tectonic modification of convergent margins: An example from southern Alaska

    Science.gov (United States)

    Farris, David W.

    Southern Alaska is an excellent natural laboratory to study forearc/arc subduction zone magmatism and tectonics. Understanding these processes are important to understanding the evolution and modification of continental crust. This thesis focuses on the Kodiak Islands, but also examines larger-scale features throughout southern Alaska and cordilleran tectonics. Kodiak Island intrusive rocks differ in character across the Border Ranges fault system (BRF). North of the BRF is the tilted Triassic-Jurassic Talkeetna island arc. This arc section exposes ultramafic mantle through mid to upper crustal plutonic and volcanic rocks all of which are geochemically related, despite being fault-bounded blocks. South of the BRF lie Paleocene intrusive rocks related to eastward spreadingridge subduction migration. These rocks are distributed in two belts: the Kodiak batholith and the trenchward belt. The Kodiak batholith is composed of granitic plutons emplaced as a series of intermingled, 1-8 km wide, viscoelastic diapirs that ascended by downward transport of aureole rocks through and around the magmatic column, and range in age from 59.2-58.4+/-0.2 Ma (SW-NE). These plutons formed from equilibrium crystallization of an argillite/graywacke derived magma, and contain fractally fragmented meta-sedimentary xenoliths. Trenchward belt rocks lie south of the Contact fault and are composed of small gabbroic to granitic plutons, dikes and pillows that range in age from 62.6+/-0.6-60.15+/-0.86 Ma (SW-NE). They formed by assimilation fractional crystallization of MORB with an argillite assimilant. Trenchward belt rocks intruded when a spreading ridge first entered the accretionary prism, whereas the Kodiak batholith formed when a slab window opened at 15-20 km depth. Age differences between the two Paleocene magmatic belts are explained by oblique ridge subduction and Contact fault displacement. The Kodiak batholith is part of the 2100 km Sanak-Baranof belt of forearc magmatism. Along

  19. Effect of desaturation and re-saturation on shale in underground galleries

    International Nuclear Information System (INIS)

    The aim of this thesis is to characterize by experimental and numerical approaches the hydric, mechanical and hydro-mechanical effects due to the desaturation and re-saturation of the Eastern argillite, host rock of the Bure site, future underground radioactive waste disposal facility. Experimental and numerical approaches for the characterization of hydric transfers in argilites are presented. A simple identification method is proposed which uses the determination of the linearized hydric diffusivity from weight measurements performed on samples (thin tubes and plates) submitted to humidity steps according to a desaturation-re-saturation cycle. The hydric transfer is nonlinear. In order to interpret this phenomenon, a non-linear numerical model is established which takes into account the physical phenomena (hydraulic conduction, vapor diffusion, phase change..). The evolution of the physical and mechanical behaviour of the argillaceous rock with respect to the imposed humidity is then analyzed according to a desaturation-re-saturation cycle by successive steps. The hydric deformation, the velocity of ultrasonic waves propagation, the elastic properties, the rupture characteristics and the delayed phenomena depend on the hydric state of the material. The desaturation and re-saturation influence on a scale model of tunnel is analyzed. Thick tubes parallel or perpendicular to the stratification are used to show up the anisotropy of the rock. These tubes are submitted to hydric loads by blowing air with variable hygrometry through their center hole. A nonlinear poro-elastic model is used to interpret the anisotropic hydro-mechanical phenomena observed. It is shown that hydric loads can lead to the rupture of test samples which follow the anisotropic directions of the rock and which can be interpreted by the hydro-mechanical model as a violation of a rupture criterion in total pulling stress. Finally, numerical calculations for the phenomena generated by desaturation

  20. Fault detection using transmission tomography - Evaluation on the Experimental Platform of Tournemire

    International Nuclear Information System (INIS)

    Deep argillaceous formations have physical properties adapted to the radioactive waste disposal but their permeability properties can be modified by the presence of fractured zones; detection of these faulted zones are thus of primary importance. Several experiments have been led by IRSN in the Experimental Platform of Tournemire where faults with small vertical offsets in the deep argillaceous formation have been identified from underground installations. Some previous studies have shown the difficulty to detect this fractured zone from surface acquisitions using reflection or refraction seismic but also with electrical methods. We here propose a new seismic transmission acquisition geometry in where seismic sources are deployed at the surface and receivers are installed in the underground installations. In the scope to process these data, a new tomography algorithm has been developed in order to control the inversion parameters and also to introduce a priori information. Several synthetic tests have been led to reliably analyze the results in terms of resolution and relevance of the final image. A discontinuity of the seismic velocities in the limestones and argillites of the Tournemire Platform is evidenced for the first time by applying the algorithm to the data recently acquired. This low velocity anomaly is located just above the fracture zone visible from the underground installations and its location is also consistent with observations from the surface. (author)

  1. Physical-Property Measurements on Core samples from Drill-Holes DB-1 and DB-2, Blue Mountain Geothermal Prospect, North-Central Nevada

    Science.gov (United States)

    Ponce, David A.; Watt, Janet T.; Casteel, John; Logsdon, Grant

    2009-01-01

    From May to June 2008, the U.S. Geological Survey (USGS) collected and measured physical properties on 36 core samples from drill-hole Deep Blue No. 1 (DB-1) and 46 samples from drill-hole Deep Blue No. 2 (DB-2) along the west side of Blue Mountain about 40 km west of Winnemucca, Nev. These data were collected as part of an effort to determine the geophysical setting of the Blue Mountain geothermal prospect as an aid to understanding the geologic framework of geothermal systems throughout the Great Basin. The physical properties of these rocks and other rock types in the area create a distinguishable pattern of gravity and magnetic anomalies that can be used to infer their subsurface geologic structure. Drill-holes DB-1 and DB-2 were spudded in alluvium on the western flank of Blue Mountain in 2002 and 2004, respectively, and are about 1 km apart. Drill-hole DB-1 is at a ground elevation of 1,325 m and was drilled to a depth of 672 m and drill-hole DB-2 is at a ground elevation of 1,392 m and was drilled to a depth of 1522 m. Diameter of the core samples is 6.4 cm. These drill holes penetrate Jurassic and Triassic metasedimentary rocks predominantly consisting of argillite, mudstone, and sandstone; Tertiary diorite and gabbro; and younger Tertiary felsic dikes.

  2. Fundamental geological elements for the occurrence of Chinese marine oil and gas accumulations

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Paleozoic strata in the Tarim Basin, Sichuan Basin and Ordos Basin are the major targets for marine petroleum exploration, with developed high quality hydrocarbon, mainly argillite. The deep burial of these source rocks suggests that they mainly develop gas instead of oil. But different maturities of organic matter may lead to different hydrocarbon facies. Through thermochemical sulfate reduction (TSR), the hydrocarbon in the carbonate rocks may undergo a process of pyrolytic cracking and be catalyzed into gases. The marine reservoirs mainly consist of carbonate and clastic rocks, and the former is controlled by sedimentary facies, dolomitization, solution, TSR and cracking. The multiphase tectonic cycling develops multiple source-reservoir-cap combinations and diversified types of traps and reservoirs, featuring multiphase reservoir formation, mainly late-phase formation or consolidation.Palaeo-uplifts play a controlling role in hydrocarbon accumulation. Differences in major source rocks in the three basins lead to different locations of oil-gas accumulation layers, different types and patterns of reservoirs and different features of reservoir formation.

  3. Calcium-aluminum-silicate-hydrate "cement" phases and rare Ca-zeolite association at Colle Fabbri, Central Italy

    Science.gov (United States)

    Stoppa, F.; Scordari, F.; Mesto, E.; Sharygin, V.; Bortolozzi, G.

    2010-06-01

    Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) — "cement" phases - i.e., thaumasite, strätlingite and an ettringite-like phase and several different species of zeolites: chabazite-Ca, willhendersonite, gismon-dine, three phases bearing Ca with the same or perhaps lower symmetry of phillipsite-Ca, levyne-Ca and the Ca-rich analogue of merlinoite. In addition, apophyllite-(KF) and/or apophyllite-(KOH), Ca-Ba-carbonates, portlandite and sulphates were present. A new polymorph from the pyrrhotite group, containing three layers of sphalerite-type structure in the unit cell, is reported for the first time. Such a complex association is unique. Most of these minerals are specifically related to hydration processes of: (1) pyrometamorphic metacarbonate/metapelitic rocks (natural analogues of cement clinkers); (2) mineralization between intrusive stocks and slates; and (3) high-calcium, alkaline igneous rocks such as melilitites and foidites as well as carbonatites. The Colle Fabbri outcrop offers an opportunity to study in situ complex crystalline overgrowth and specific crystal chemistry in mineral phases formed in igneous to hydrothermal conditions.

  4. Mineralogy, Geochemistry and Stable Isotope Studies of the Dopolan Bauxite Deposit, Zagros Mountain, Iran

    Directory of Open Access Journals (Sweden)

    Somayeh Salamab Ellahi

    2016-02-01

    Full Text Available The Dopolan deposit is a Mediterranean-type bauxite located in the Zagros Fold-Thrust Zone, Iran. This deposit consists of five lithological members including iron-rich, clay-rich, oolitic, pisolitic and organic matter-containing bauxites. The mineralogy of the deposit includes diaspore, boehmite, and kaolinite, nacrite, with minor pyrite, anatase and rutile. Geochemical studies show that light rare earth elements (LREEs are enriched relative to heavy rare earth elements (HREEs in all members, supporting an authigenic origin. Mass changes based on Ti as an immobile element indicate that conventionally-immobile elements (Al, Nb, Ta, Zr, Hf are enriched in situ in the residual units, whereas mobile elements (K, Ca, Si were depleted during bauxitization. This study shows that the Khaneh–Kat argillitic dolomite is the likely parent rock. The δ18O (7.63‰to 9.35‰ and D values (49.91‰to 66.49‰ for kaolinite in the bauxite samples suggest equilibration with meteoric waters which supports a supergene origin. Bauxitization occurred in a warm climate with relatively constant isotopic composition suggesting climate stability during the development of bauxite horizons and remobilization of Al (with formation of secondary boehmite. The δ13C values of calcite (7.3‰ in the bauxite support the idea that the Khaneh–Kat Formation has experienced post-depositional isotope exchange with meteoric waters during the karstification process.

  5. Estimating thermo-osmotic coefficients in clay-rocks: II. In situ experimental approach.

    Science.gov (United States)

    Trémosa, J; Gonçalvès, J; Matray, J M; Violette, S

    2010-02-01

    Water flow in compacted shales is expected to be modified by thermo-osmosis when a thermal gradient exists. However this coupled-flow process is poorly characterized since no experiments on non-remoulded clay-rocks are found in the literature. This paper presents a set of thermo-osmosis experiments carried out in an equipped borehole installed in the Liassic argillite at the Institut for Radiological protection and Nuclear Safety (IRSN) underground research laboratory (URL) of Tournemire (southeastern France). A numerical model - including coupled-flow equations, mass conservation laws, thermal expansion and changes of water properties with temperature - was developed for the interpretation of these experiments. A thermo-osmotic response was deduced from the pressure evolution in the test interval after temperature pulses (+2.5, +5.1, and +9 degrees C). The values of thermo-osmotic permeability determined during the experiments range between 6x10(-12) and 2x10(-10)m(2)K(-1)s(-1), depending on the pulse temperature and uncertainties on the model parameters. A sensitivity analysis on several model parameters was performed to constrain these uncertainties. PMID:19861223

  6. Reinterpretation of Mesozoic ophiolite arc, and blueschist terranes in southwestern Baja California

    Energy Technology Data Exchange (ETDEWEB)

    Sedlock, R.L. (San Jose State Univ., CA (United States). Geology Dept.)

    1993-04-01

    The nature and significance of disrupted Mesozoic oceanic rocks on Isla Santa Margarita and Isla Magdalena, western Baja California Sur, have been reinterpreted on the basis of detailed mapping and petrologic studies. Three structural units are recognized. (1) The upper plate consists of ophiolitic, arc, and forearc basin rocks. Ophiolitic rocks, including metamorphosed ultramafic rocks, gabbro, dikes, volcanic rocks, and chert, underwent strong contractional deformation and penetrative greenschist-facies metamorphism. Arc rocks, including gabbro, a dike and sill complex, compositionally diverse volcanic rocks, lahars, and volcaniclastic strata, lack a penetrative fabric and are weakly metamorphosed. Forearc basin rocks consist of unmetamorphosed conglomerated and rhythmically bedded siliciclastic turbidites. (2) The lower plate is a subduction complex consisting of weakly to moderately foliated and metamorphosed pillow and massive lavas, breccia, and tuff( ), interbedded red and green siliceous argillite, and rare radiolarian ribbon chert and limestone. Blueschist-facies metamorphism is indicated by lawsonite, aragonite, sodic amphibole, and sodic clino-pyroxene. (3) Serpentine-matrix melange crops out in shallowly dipping fault zones between the upper and lower plates. The structural and petrologic characteristics of the Mesozoic units, the geometry of contacts between them, and the age of extension are similar to those in the Isla Cedros-Vizcalno Peninsula region, 400 km to the northwest. The author infers that syn-subduction extension was a regional event that affected much of the western Baja forearc during the Late Cretaceous and Paleogene.

  7. Review of potential host rocks for radioactive waste disposal in the southeast United States-Southern Piedmont subregion

    Energy Technology Data Exchange (ETDEWEB)

    1980-10-01

    A literature study was conducted on the geology of the Southern Piedmont province in the states of Maryland, Virginia, North Carolina, South Carolina, and Georgia. The purpose was to identify geologic areas potentially suitable for containment of a repository for the long-term isolation of solidified radioactive waste. The crystalline rocks of the Southern Piedmont province range in age from Precambrian to Paleozoic, and are predominantly slates, phyllites, argillites, schists, metavolcanics, gneisses, gabbros, and granites. These rock units were classified as either favorable, potentially favorable, or unfavorable as potential study areas based on an evaluation of the geologic, hydrologic, and geotechnical characteristics. No socio-economic factors were considered. Rocks subjected to multiple periods of deformation and metamorphism, or described as highly fractured, or of limited areal extent were generally ranked as unfavorable. Potentially favorable rocks are primarily the high-grade metamorphic gneisses and granites. Sixteen areas were classified as being favorable for additional study. These areas are primarily large igneous granite plutons as follows: the Petersburg granite in Virginia; the Rolesville-Castallia, Churchland, and Landis plutons in North Carolina; the Liberty Hill, Winnsboro, and Ogden plutons in South Carolina; and the Siloam, Elberton, and six unnamed granite plutons in Georgia.

  8. Review of potential host rocks for radioactive waste disposal in the southeast United States-Southern Piedmont subregion

    International Nuclear Information System (INIS)

    A literature study was conducted on the geology of the Southern Piedmont province in the states of Maryland, Virginia, North Carolina, South Carolina, and Georgia. The purpose was to identify geologic areas potentially suitable for containment of a repository for the long-term isolation of solidified radioactive waste. The crystalline rocks of the Southern Piedmont province range in age from Precambrian to Paleozoic, and are predominantly slates, phyllites, argillites, schists, metavolcanics, gneisses, gabbros, and granites. These rock units were classified as either favorable, potentially favorable, or unfavorable as potential study areas based on an evaluation of the geologic, hydrologic, and geotechnical characteristics. No socio-economic factors were considered. Rocks subjected to multiple periods of deformation and metamorphism, or described as highly fractured, or of limited areal extent were generally ranked as unfavorable. Potentially favorable rocks are primarily the high-grade metamorphic gneisses and granites. Sixteen areas were classified as being favorable for additional study. These areas are primarily large igneous granite plutons as follows: the Petersburg granite in Virginia; the Rolesville-Castallia, Churchland, and Landis plutons in North Carolina; the Liberty Hill, Winnsboro, and Ogden plutons in South Carolina; and the Siloam, Elberton, and six unnamed granite plutons in Georgia

  9. Ground magnetic studies along a regional seismic-reflection profile across Bare Mountain, Crater Flat and Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Ground magnetic data were collected along a 26-km-long regional seismic-reflection profile in southwest Nevada that starts in the Amargosa Desert, crosses Bare Mountain, Crater Flat and Yucca Mountain, and ends in Midway Valley. Parallel ground magnetic profiles were also collected about 100 m to either side of the western half of the seismic-reflection line. The magnetic data indicate that the eastern half of Crater Flat is characterized by closely-spaced faulting (1--2 km) in contrast to the western half of Crater Flat. Modeling of the data indicates that the Topopah Spring Tuff is offset about 250 m on the Solitario Canyon fault and about 50 m on the Ghost Dance fault. These estimates of fault offset are consistent with seismic-reflection data and geologic mapping. A broad magnetic high of about 500--600 nT is centered over Crater Flat. Modeling of the magnetic data indicates that the source of this high is not thickening and doming of the Bullfrog Tuff, but more likely lies below the Bullfrog Tuff. Possible source lithologies for this magnetic high include altered argillite of the Eleana Formation, Cretaceous or Tertiary intrusions, and mafic sills

  10. Thermo-hydro-mechanical processes in the nearfield around a HLW repository in argillaceous formations. Vol. II. In-situ-investigations and interpretative modelling. May 2007 to May 2013

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chun-Liang; Czaikowski, Oliver; Komischke, Michael; Wieczorek, Klaus

    2014-06-15

    Deep disposal of heat-emitting high-level radioactive waste (HLW) in clay formations will inevitably induce thermo-hydro-mechanical-chemical disturbances to the host rock and engineered barriers over very long periods of time. The responses and resulting property changes of the natural and engineered barriers are to be well understood, characterized, and predicted for assessing the long-term performance and safety of the repositories. In accordance with the R and D programme defined by the German Federal Ministry of Economics and Technology (BMWi), GRS has intensively performed site-independent research work on argillaceous rocks during the last decade. Most of the investigations have been carried out on the Callovo-Oxfordian argillite and the Opalinus clay by par-ticipation in international research projects conducted at the underground research laboratories at Bure in France (MHM-URL) and Mont-Terri in Switzerland (MT-URL). The THM-TON project, which was funded by BMWi under contract number 02E10377, in-vestigated the THM behaviours of the clay host rock and clay-based backfill/sealing materials with laboratory tests, in situ experiments and numerical modelling.

  11. Modeling solute in clays at the nano-metric scale Part I. Application to the alkaline series

    International Nuclear Information System (INIS)

    The argillite formation has been proposed as a potential host rock for deep radioactive waste disposal. These materials have very low permeability and diffusion is likely to be the predominant transfer mechanism for solute migration.The negatively charged surface of the clays induces unexpected behaviour of the ions: while the anions diffuse slower than HTO, the transport of the cations is accelerated. To explain these two antagonistic phenomena, 'effective diffusion porosity' for anions and 'surface diffusion' for cations has usually been introduced. The aim of the present study is to describe the main mechanism that takes place in the vicinity of the charged surface (nano-metric scale) and enables to quantify the behaviour of the alkaline series (from Li to Cs), i.e increase the retention and effective diffusion coefficient from lithium to caesium. This model with few inputs can quantitatively reproduced specific adsorption of monovalent cations and adsorption isotherm for Rb, Cs. Hydration and electrostatic forces seem to be the main interactions controlling the adsorption on surface for the alkaline series. (authors)

  12. Facies analysis of the Codó Formation (Late Aptian in the Grajaú Area, Southern São Luís-Grajaú Basin

    Directory of Open Access Journals (Sweden)

    Rossetti Dilce F.

    2004-01-01

    Full Text Available Facies descriptions of the Codó Formation in the Grajaú area are provided for the first time, and its sedimentary characteristics compared to those from the Codó area to allow paleoenvironmental reconstructions. Deposits in the Grajaú area include evaporites, limestones and argillites bearing features indicative of a shallow, low energy, subaqueous, saline environment exposed to meteoric and/or capillary conditions. Flooding-evaporative concentration-desiccation cycles suggest a saline pan complex surrounded by extensive evaporitic mudflats. The location of the system, whether coastal or inland, is a matter open for debate. However, the later hypothesis is favored considering: 1. Sr isotopic data, with values higher than those expected for Late Aptian marine waters; 2. calcitic composition of limestones (instead of dolomitic and/or magnesitic as expected in coastal settings; and 3. presence of continental ostracods and lack of marine fauna. This interpretation is consistent with that proposed for UpperAptian deposits of the Codó area, but the depositional system there was one dominated by more stable, well-stratified, anoxic waters and evaporite precipitation in central lacustrine areas, while in the Grajaú area the salt pan was more oxygenated and ephemeral, with salt precipitation mainly in marginal areas or along surrounding mudflats.

  13. Sediment-hosted/orogenic gold mineral systems exploration using PALSAR remote sensing data in Peninsular Malaysia

    Science.gov (United States)

    Beiranvand Pour, Amin; Hashim, Mazlan

    2016-06-01

    The Bentong-Raub Suture Zone (BRSZ) is genetically related to the sediment-hosted/orogenic gold deposits associated with the major lineaments and form-lines in the Central Gold Belt of Peninsular Malaysia. In this investigation, the Phased Array type L-band Synthetic Aperture Radar (PALSAR) satellite remote sensing data were used to analyse major geological structures in Peninsular Malaysia and provide detailed characterization of lineaments and form-lines in the BRSZ, as well as its implications for sediment-hosted/orogenic gold exploration in tropical environments. The pervasive array of N-S faults in the study area and surrounding terrain is mainly linked to the N-S trending of the BRSZ Suture Zone. N-S striking lineaments are often cut by younger NE-SW and NW-SE-trending lineaments. Three generations of folding event have been discerned from remote sensing structural analysis. Gold mineralized trends lineaments are associated with the intersection of N-S, NE-SW, NNW-SSE and ESE-WNW faults and curvilinear features in shearing and alteration zones. Compressional tectonics structures such as NW-SE trending thrust, ENE-WSW oriented faults in mylonite and phyllite, recumbent folds and asymmetric anticlines in argillite are high potential zones for gold prospecting.

  14. Long-term decline of 137Cs concentration in honey in the second decade after the Chernobyl accident

    International Nuclear Information System (INIS)

    In the years 2001-2004 the 137Cs activity was investigated in a total of 336 samples of different varieties of honey harvested in the Liguria Region of Northern Italy. Our purpose was to define (a) residual radioactive contamination following the Chernobyl accident and 137Cs long-term decline, (b) correlation between 137Cs activity and different honey varieties, and (c) correlation between 137Cs activity and the prevailing geomorphological configuration in the collection areas. The mean 137Cs specific activity was 4.33 ± 5.04 S.D. Bq/kg. Chestnut honey showed higher levels of radioactive contamination, which were ascribed to the extensive, superficial and deep, root apparatus of the tree. Honey samples from acidic argillite soils, which withhold radionuclides after deposition and slowly release them to plants, also showed higher 137Cs activity. Long-term decline was calculated at 456 days, a value lower than those published from different food sources in the years following the accident. The rate of long-term decline decreases with time

  15. Tracing the origin of water and solute transfers in deep groundwater from Oxfordian, Dogger and Trias formations in the east of the Paris Basin - France

    International Nuclear Information System (INIS)

    In order to assess the feasibility for long lived radioactive wastes storage facilities in deep geological formation, solute transport processes must be investigated in the vicinity of the host formation. In France, the Oxfordian and Dogger limestone layers surrounding the Callovo-Oxfordian (COx) argillite in the east of the Paris Basin are investigated for this purpose. More than 60 samples of Oxfordian and Dogger formation groundwater and one sample of Triassic formation groundwater, located at the bottom section of the investigated sedimentary cover, were collected over a 250 km2 area, and were analysed for major ions, δ18O and δ2H of water, 87Sr/86Sr/, and δ34S and δ18O of dissolved sulphate. Oxfordian and Dogger formation water is from meteoric origin, and no direct water flow between Oxfordian, Dogger, nor Triassic formations was evidenced. Mineralization processes of the Dogger limestone groundwater were fully investigated. These processes correspond to a series of geochemical reactions including: calcite dissolution, incongruent dissolution of dolomite, ion addition from upward vertical diffusion through the sedimentary pile inducing cation exchange and further dissolution due to the increased ionic strength of the solutions. A PHREEQC model was developed to simulate inferred chemical processes. The model output is consistent with observed data. (authors)

  16. Coupled-processes in the Callovo-Oxfordian shales at the Bure site: implications for the transports of water and solutes

    International Nuclear Information System (INIS)

    This research thesis is related to the ANDRA's project of building a deep storage site for long-life, high- and medium-activity radioactive wastes within a Callovo-Oxfordian geological formation which is investigated by the Bure underground laboratory. As previous studies revealed hydrostatic loads greater than expected, the objective of this research is to explain these overpressures by validating or invalidating hypotheses on natural phenomena which could cause them. These hypotheses are: a progressive decrease of rock porosity in relationship with a continuous increase of mechanical stresses in the Callovo-Oxfordian, the existence in the past of hydrostatic pressures greater than now, and an osmotic effect. The author gives an overview of the knowledge about clays and their interactions with surrounding solutes, about coupled flows and overpressures. Based on petro-physical data, she proposes an assessment of the chemical osmotic coupling coefficient. Based on experimental and numerical investigations, she reports the measurement of this coefficient in the Callovo-Oxfordian argillites, and then proposes new interpretations of the measured overpressures

  17. The characteristics of uranium mineralization and genesis of Nuheting uranium deposit in Erlian basin Inner Mongolian

    International Nuclear Information System (INIS)

    The Nuheting uranium deposit is located at the northern margin of Erlian basin in Inner Mongolian. Uranium mineralizations are localized in the Erlian formation of upper Cretaceous system. Main types of ore are argillite, argillaceous siltstone and argillaceous graywacke. There are 3 main mineral associations in places with uranium: uranium-gypsum-celestione; uranium-pyriteorganic matter; uranium-pyrite, marcasite and other metalliferous sulfides. Uranium is mainly adsorbed and pitchblende in minor amount can also be found. The formation of economic uranium orebody is related with migration of oil and gas, because there are organic matter of aromatic hydrocarbon and moving hydrocarbon in uranium ore. The U-Pb isotopic ages of ore and pitchblende are 85, 40 and 10 Ma, which indicate that Nuheting uranium deposit was formed in long-term geological process and principally underwent three main stages: Sedimentary diagenesis; migration of oil and gas; and stage of supergene reworking. Therefore, the deposit should be classified as polygenetic type. (9 tabs.; 3 figs)

  18. Detection of cracks with low vertical offset in clayey formations from galleries by using seismic methods. Tournemire experimental station. First part: problem analysis and measurement sizing

    International Nuclear Information System (INIS)

    Within the frame of the expertise of the ANDRA file on the project of storage of radioactive wastes in clayey formations, the detection of natural cracks which could locally alter the argillite containment properties is a crucial issue. As some previous studies showed that some cracks exhibiting a low vertical offset could not be detected in clayey formations from the surface, this document reports a study which aimed at assessing the possibility of detection of such a crack by means of seismic methods directly implemented from underground works. It reports a detailed analysis of the seismic imagery problem, the characterization of different areas of the investigated environment, the assessment and validation of various hypotheses by using experimental data obtained in an experimental station and numerical simulations. The potential of each envisaged method (migration, tomography, wave form inversion) is assessed, notably with respect to synthetic seismic data obtained by numerical modelling. Preliminary results are used to size a complete seismic measurement campaign aimed at the characterization of the crack area, and at the assessment of detection limitations of the different methods

  19. X-ray Micro Tomography as a Tool for Studying Localized Damage / Deformation in Clay Rock

    International Nuclear Information System (INIS)

    Deformation in geo-materials (soils, rocks, concrete, etc.) is often localized, e.g., in the form of shear bands or fractures. In experimental analysis of the mechanical behavior of such materials, standard laboratory methods are insufficient as the majority of measurements are made at the sample scale and rarely at a local scale. X-ray tomography monitoring during loading allows high-resolution full-field observation of the development of deformation. However, such images only indicate clearly the de-formation when there are significant changes in material density (i.e., volume changes) that produce a change in x-ray absorption. As such 3D Digital Image Correlation (DIC) approaches have been developed that allow quantification of the full strain tensor field throughout the imaged volume. This paper presents results from triaxial compression tests on a clay rock (Callovo-Oxfordian argillite) with in situ synchrotron x-ray micro tomography imaging providing complete 3D images of the specimen at several stages throughout the test. These images have been analyzed using 3D DIC to provide full-field displacement and strain measurements, which allowed the detection of the onset of strain localization and its timing relative to the load peak plus insight into the 3D structure of the localized zone. The paper concludes with a few general remarks concerning the lessons learned from this study and perspectives for current and future work. (authors)

  20. Geo-electrical characterization of the excavation disturbed zone (EDZ) in the experimental platform of Tournemire

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. The French Institute for Radiation protection and Nuclear Safety (IRSN) has selected the experimental Tournemire site (Aveyron, France) to study the confinement properties of the argillaceous media and damages induced by galleries' excavation. Electrical resistivity and induced polarization tomography have been performed to address in the field the capabilities of electrical methods for characterizing the EDZ. Four geo-electrical surveys were performed in three different galleries of the Tournemire's URL: the eastern gallery excavated in 1996 (GE-96), the eastern gallery excavated in 2003 (GE-03) and finally the northern gallery excavated in 2008 (GN-08). The geo-electrical surveys consisted in 2D longitudinal and circular profiles including 48 and 43 electrodes (separation of 20 cm) respectively. Non-polarizing Cu/CuSO4 electrodes (9 mm in diameter) were used and installed in micro-drillings filled with wet bentonite. Measurements were carried out with a Syscal Pro device (IRIS instruments). Measured apparent resistivity and chargeability values were inverted with Res2Dinv software. The results obtained from the first survey in June 2008 in GE-96 confirmed that electrical methods were able to localize the non saturated and fractured zones around the gallery. Additional measurements were carried out in the same gallery with the same experimental procedure for a dry atmosphere period, i.e. in February 2009. The results of this second survey indicated a more important desaturation of argillite around fractures (characterized by higher electrical resistivity values) enhanced by the initial shallow fractures in connection with a drier atmosphere. Moreover, inverted Induced Polarization (IP) data have shown a strong spatial correlation between important chargeability anomalies and calcite-filled tectonic fractures. However, neo-formed fractures (with no filling), associated with a mechanical damage, didn

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

    International Nuclear Information System (INIS)

    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

  2. Influence of chemistry and climate on large induced large scale stresses in anisotropically fractured carbonates.

    Science.gov (United States)

    Toussaint, R.; Cornet, F.

    2012-04-01

    We will explore a simple model coupling for carbonate rocks the fracture density and orientation, the water chemistry and transport, the dissolution reactions and the expected irreversible rock deformation. Adding elasticity and boundary conditions, plus an estimation of the water source composition in the formation, we will estimate orders of magnitudes of the stress changes that can be expected from these processes in sedimentary basins over long times. We will in particular examine whether such intrinsic deformation mechanism can give a hint to explain the observed anisotropic stresses, in orientation and magnitude, in zones above the C.O.X. argillite formation in the Paris Basin, where the horizontal stress anisotropy has been shown to be important, whereas stress decoupling from the deep crustal roots should be effective, and no strong anisotropy would be expected in the absence of active deformation mechanism. In the Paris basin, the analysis of log cores shows that fractures and joints, up to meter-long ones, are common anisotropic features present in the carbonate rocks. Dissolution of calcite along these oriented features removes material with an a priori oriented flux reflecting this structural anisotropy, resulting in a non-isotropic deformation associated to this dissolution. We will present a simple model where dissolution and transport of dissolved calcite is associated with the deformation of the carbonate rock. Estimating the reaction constants, the chemical composition variation of the meteoric water, the rock permeability and the fracture density from observations around the Bure underground laboratory, we will estimate the order of magnitude of the deformations expected from these types of mechanisms. Such estimates have already been performed for dissolution along stylolites, e.g. by Clark, 1966; Renard et al., 2004; Schmittbuhl et al., 2004; Koehn et al., 2007. We will adapt these to reflect the anisotropic feature of the fractures present in

  3. Fe(0)-Kaolinite (KGA2) interactions at 90° C under anoxic conditions

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Because of the use of steel containers for geological deposit of nuclear waste, it is of prime importance to understand the interaction mechanisms between the geological matrix, Callovo-Oxfordian argillite, and the steel container. In order to evidence the individual role of each different clay phase entering in the mineralogy of the Callovo-Oxfordian argillite, the iron-clay interactions were studied by the use of reference clays. The Georgia Kaolinite (KGa2) supplied by the Clay Mineral Society was selected to represent kaolinite minerals; as it has been extensively characterized in our laboratory. To reproduce the repository conditions, raw kaolinite was put in contact with powder metallic iron with a weight ratio fixed at 1/3 and a solid/liquid ratio of 1/20. Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L-1, CaCl2 0.04 M.L-1) in Parr reactors for durations of one, three or nine months. Similar experiments without iron were carried out to show up the influence of iron on mineralogical transformations in such conditions. After, one, three or nine months, solid and liquid phases were separated by centrifugation and characterized by classical techniques combining chemical analyses, X-ray diffraction, Fourier Transform Infrared spectroscopy, scanning and transmission electron microscopy, XPS and Moessbauer analyses. Supplementary observation tools, based on the use of synchrotron radiation were used to reinforce the information about iron localisation and its status in individualized clay particles (Scanning Transmission X-ray Microscopy (STXM) and Micro-Xray Absorption Spectroscopy (μ-XAS)). Without iron, kaolinite KGa2 remains unchanged, from a mineralogical point of view, even after nine months in suspension. With iron, first results from one month experiments showed a decrease of pristine metallic iron as well as the apparition of

  4. Are distribution coefficients measured from batch experiments meaningful for quantifying retention in compacted material?

    International Nuclear Information System (INIS)

    distribution coefficient. The equilibrium state is checked with activity measurement of the aqueous phase at consistent elapse time. Callovo-Oxfordian argillite is a natural compacted material, then square pieces (1 x 1 cm2) are produced from rough material. In the simulated site water, the Callovo-Oxfordian argillite does not weather. In order to ensure that chemical equilibrium is reached before addition of radioactive tracers, a pre-equilibration period is going on for at least 2 month. All adsorption experiments are followed by desorption experiments. The distribution coefficient onto aqueous suspensions of bentonite and Callovo-Oxfordian are calculated and compared to those found for compacted materials. Main results are discussed towards literature values. [1] Miyahara, K. A., T.; Kohara,Y.; Yusa,Y.; Sasaki, N. (1991). 'Effect of bulk density on diffusion for cesium in compacted sodium bentonite'. Radiochimica acta 52/53: 293-297. [2] Sato, H. A., T.; kohara, Y.; Yui, M.; Sasaki, N. (1992). 'Effect of dry density of some radionuclides in compacted sodium bentonite'. Journal of Nuclear Science and technology 29(9): 873-882. [3] Ly, J. L. V., J-C.; Meier, P. (1998). Retention dans une barriere argileuse en milieu granitique: Effet de la consolidation et de la composition de l'eau. Paris, CEA: 32. (authors)

  5. Electrical studies at the proposed Wahmonie and Calico Hills nuclear waste sites, Nevada Test Site, Nye County, Nevada

    Science.gov (United States)

    Hoover, D.B.; Chornack, Michael P.; Nervick, K.H.; Broker, M.M.

    1982-01-01

    Two sites in the southwest quadrant of the Nevada Test Site (NTS) were investigated as potential repositories for high-level nuclear waste. These are designated the Wahmonie and Calico Hills sites. The emplacement medium at both sites was to be an inferred intrusive body at shallow depth; the inference of the presence of the body was based on aeromagnetic and regional gravity data. This report summarizes results of Schlumberger VES, induced polarization dipole-dipole traverses and magnetotelluric soundings made in the vicinity of the sites in order to characterize the geoelectric section. At the Wahmonie site VES work identified a low resistivity unit at depth surrounding the inferred intrusive body. The low resistivity unit is believed to be either the argillite (Mississippian Eleana Formation) or a thick unit of altered volcanic rock (Tertiary). Good electrical contrast is provided between the low resistivity unit and a large volume of intermediate resistivity rock correlative with the aeromagnetic and gravity data. The intermediate resistivity unit (100-200 ohm-m) is believed to be the intrusive body. The resistivity values are very low for a fresh, tight intrusive and suggest significant fracturing, alteration and possible mineralization have occurred within the upper kilometer of rock. Induced polarization data supports the VES work, identifies a major fault on the northwest side of the inferred intrusive and significant potential for disseminated mineralization within the body. The mineralization potential is particularly significant because as late as 1928, a strike of high grade silver-gold ore was made at the site. The shallow electrical data at Calico Hills revealed no large volume high resistivity body that could be associated with a tight intrusive mass in the upper kilometer of section. A drill hole UE 25A-3 sunk to 762 m (2500 ft) at the site revealed only units of the Eleana argillite thermally metamorphosed below 396 m (1300 ft) and in part highly

  6. Sensitivity analysis of alkaline plume modelling: influence of mineralogy

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the context of a disposal facility for radioactive waste in clayey geological formation, an important modelling effort has been carried out in order to predict the time evolution of interacting cement based (concrete or cement) and clay (argillites and bentonite) materials. The high number of modelling input parameters associated with non negligible uncertainties makes often difficult the interpretation of modelling results. As a consequence, it is necessary to carry out sensitivity analysis on main modelling parameters. In a recent study, Marty et al. (2009) could demonstrate that numerical mesh refinement and consideration of dissolution/precipitation kinetics have a marked effect on (i) the time necessary to numerically clog the initial porosity and (ii) on the final mineral assemblage at the interface. On the contrary, these input parameters have little effect on the extension of the alkaline pH plume. In the present study, we propose to investigate the effects of the considered initial mineralogy on the principal simulation outputs: (1) the extension of the high pH plume, (2) the time to clog the porosity and (3) the alteration front in the clay barrier (extension and nature of mineralogy changes). This was done through sensitivity analysis on both concrete composition and clay mineralogical assemblies since in most published studies, authors considered either only one composition per materials or simplified mineralogy in order to facilitate or to reduce their calculation times. 1D Cartesian reactive transport models were run in order to point out the importance of (1) the crystallinity of concrete phases, (2) the type of clayey materials and (3) the choice of secondary phases that are allowed to precipitate during calculations. Two concrete materials with either nanocrystalline or crystalline phases were simulated in contact with two clayey materials (smectite MX80 or Callovo- Oxfordian argillites). Both

  7. The provenance of clasts deposited on the Surveyor Fan, Gulf of Alaska: First results of IODP Expedition 341

    Science.gov (United States)

    Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Moy, C. M.; Müller, J.; Ribeiro, F.; Ridgway, K. D.

    2013-12-01

    Provenance analysis is a key instrument for elucidating the denudation history of source terranes and for quantifying their respective contributions to sedimentary routing systems and the detrital composition of sedimentary systems. The submarine Surveyor Fan in the Gulf of Alaska is sourced by the highest coastal range on Earth, the Chugach-St. Elias orogenic system along the southern Alaska convergent margin. Exhumation, uplift and denudation of the orogenic system since the Miocene are governed by the interplay of climate with convergent tectonic processes. The denudational activity of Neogene and Quaternary glacier systems significantly influenced the exhumation and uplift history of the mountain belt, and sourced the c. 1000 km long Surveyor fan system. First results obtained in 2013 during IODP Expedition 341 at Sites U1417 and U1418, on the distal and proximal Surveyor Fan, respectively, reveal that the Miocene to Holocene stratigraphy of the Surveyor Fan is dominated by thick mud and biogenic ooze deposits. These are punctuated by debris flow deposits, thin-bedded turbidites, and diamicts. Larger clasts (granules to cobbles) occur in non-glacial Miocene to Pliocene debris flow deposits, and in glacial Pleistocene muds and diamicts as ice-rafted lonestones and debris accumulations. Here we report first onboard results of counts of lithologies occurring at both sites. The stratigraphic succession encountered at Site U1417 on the distal Surveyor Fan ranges from the non-glacial Miocene and Pliocene to the glacial Pleistocene, and Holocene. The main clast types contained in the sediment are of metamorphic origin. In decreasing order of abundance occur argillite, metasiltstone and basalt. Sandstone, siltstone, granite and quartzite are minor lithologies. When grouped as metamorphic (M), sedimentary (S) and igneous (I), the average clast ratio is M73I12S15. The stratigraphy at Site U1418 on the proximal fan covers the glacial Pleistocene, and Holocene. The clasts

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  9. Analysis of the phenomenon of material expansiveness in tunnels built in anhydrite. Outcomes and experiences

    Directory of Open Access Journals (Sweden)

    del Campo, J. M.

    2012-12-01

    Full Text Available The serious geotechnical problems arising in many tunnels bored in material giving rise to stability problems as a result of being expansive, makes the water channelizers. These are materials which are easily washed with sulphates dissolving with water causing the massif to become decompressed and to remould, aggravating and transferring the problem beyond the tunnel’s immediate environment. In the particular case of layers of anhydrite between argillite, it also happens that the primary support and subsequent lining must have exceptional strength to resist the pressures the terrain may transmit in the medium to long term. This article describes the most relevant aspects of the hydromechanical behaviour of sulphated soil and rock and presents some experiments, concluding with various aspects associated to the phenomenon of swelling in tunnels and its possible treatment.

    Los graves problemas geotécnicos sucedidos en numerosos túneles europeos excavados en materiales que generan problemas de estabilidad, como consecuencia de su expansividad, los convierten en canalizadores de aguas. Estos materiales son fácilmente lavables al disolverse los sulfatos con el agua, provocando una decompresión y remoldeo del macizo, agravando y trasladando el problema más allá del inmediato entorno del túnel. En el caso particular de presencia de capas de anhidrita entre argilitas, además de la adopción de medidas de sostenimiento y revestimiento especiales, el sostenimiento primario y el revestimiento posterior deben ser excepcionalmente resistentes a las presiones que pueden llegar a transmitir el terreno a medio y largo plazo. En este artículo se describen los aspectos más relevantes de comportamiento hidromecánico de los suelos y las rocas sulfatadas y se presentan algunas experiencias, concluyendo sobre aspectos asociados al fenómeno de hinchamiento en túneles y su posible tratamiento.

  10. Stress inversion and basement-cover stress transmission across weak layers in the Paris basin, France

    Science.gov (United States)

    Gunzburger, Yann; Magnenet, Vincent

    2014-03-01

    We investigate the source of non-purely gravitational horizontal stresses in the Paris basin, a nowadays tectonically quiet intracratonic basin, in its eastern border of which outstandingly dense stress measurements are available. Based on a synthesis of published data, the stress state in the basin is first shown to be very close to the one that may be extrapolated for the underlying basement, in terms of principal stress orientations and horizontal to vertical stress ratios. This is in favour of a mechanical coupling between the basement and its sedimentary cover, which may seem contradictory to the presence of several weak rock layers in the basin fill, e.g. an argillite layer that was shown to bear low deviatoric stresses, and salt layers that are implicated in a major décollement elsewhere. To unravel this apparent contradiction, a 3D-numerical modelling is performed, following a rigorous inverse problem approach, to determine the long-term elastic properties of both the basement and the basin rocks. The objective is to find the set of elastic constants that provides the best fit between the calculated stress state in the basin and the in situ data, by assuming that the stress state in the basement is known. This methodology provides a realistic set of mechanical parameters, in agreement with previous studies, which leads to the conclusion that the horizontal stresses in the basin constitute its mechanical response to the stresses that developed in the underlying basement during and since the last tectonic event (Alpine phase). The fact that horizontal stresses could be transmitted across the weak horizons, contrary to what may be expected at first glance, is explained both by the geometry of the basin and the fact that, over the long term, the stiffnesses of the various sedimentary rocks are only slightly different from each other.

  11. Assessment of potential radionuclide transport in site-specific geologic formations

    International Nuclear Information System (INIS)

    Associated with the development of deep, geologic repositories for nuclear waste isolation is a need for safety assessments of the potential for nuclide migration. Frequently used in estimating migration rates is a parameter generally known as a distribution coefficient, K/sub d/, which describes the distribution of a radionuclide between a solid (rock) and a liquid (groundwater) phase. This report is intended to emphasize that the use of K/sub d/ must be coupled with a knowledge of the geology and release scenarios applicable to a repository. Selected K/sub d/ values involving rock samples from groundwater/brine simulants typical of two potential repository sites, WIPP and NTS, are used to illustrate this concern. Experimental parameters used in K/sub d/ measurements including nuclide concentration, site sampling/rock composition, and liquid-to-solid ratios are discussed. The solubility of U(VI) in WIPP brine/groundwater was addressed in order to assess the potential contribution of this phenomena to K/sub d/ values. Understanding mehanisms of sorption of radionuclides on rocks would lead to a better predictive capability. Sorption is attributed to the presence of trace constituents (often unidentified) in rocks. An attempt was made to determine if this applied to WIPP dolomite rocks by comparing sorption behavior of the natural material with that of a synthetic dolomite prepared in the laboratory with reagent grade chemicals. The results were inconclusive. The results of a study of Tc sorption by an argillite sample from the Calico Hills formation at NTS under ambient laboratory conditions were more conclusive. The Tc sorption was found to be associated with elemental carbon. Available evidence points to a reduction mechanism leading to the apparent sorption of Tc on the solid phase

  12. Inventory of clay-rich bedrock and metamorphic derivatives in eastern Nevada, excluding the Nevada Test Site

    International Nuclear Information System (INIS)

    Six counties of eastern Nevada contain 36 localities that include areas of exposed clay-rich sedimentary bedrock, slightly to moderately metamorphosed derivatives of such rocks, or both. In each locality one or more of these kinds of rocks constitute one or more geologic units greater than 152 m (500 ft) in thickness and 0.8 km2 (0.3 m2) in area at the ground surface. The sedimentary and metamorphic rocks locally meet or exceed arbitrarily selected minimum conditions of lithology, thickness, and areal extent. These places are grouped into localities and may be deemed suitable for further investigation. The localities identified are in Clark, Elko, Eureka, Lincoln, Nye, and White Pine Counties. The types of clay-rich rocks that might be useful include claystone, siltstone, shale, and various mixtures of them, together with metamorphic derivatives which include argillite, metasiltstone, slate, phyllite, schist, and gneiss. The geologic units that contain such clay-rich rocks also commonly contain mixtures, interlayers, and lenses of sandstone, conglomerate, and limestone, and their metamorphic derivatives: quartzite, conglomerite, and marble. Initially, the principal areas in Nevada where clay-rich rocks more than 31 m (100 ft) thick are exposed at the ground surface were identified by searching published geologic literature. From those areas, localities that contain exposed clay-rich rocks more than 152 m (500 ft) thick and of more than 0.8 km2 (0.3 mi2) in areas were selected. For each locality a brief descriptive text was prepared. Seven factors that might be significant in selecting localities best suited for further investigation are summarized therein. The factors are: (1) geographic location, (2) land ownership, (3) accessibility, (4) proximity to population concentration, (5) geologic setting, (6) hydrologic setting, and (7) mineral-resource activity

  13. Petrology, Magnetic susceptibility, Tectonic setting and mineralization associated with Plutonic and Volcanic Rocks, Eastern Bajestan and Taherabad, Iran

    Directory of Open Access Journals (Sweden)

    Malihe Ghoorchi

    2009-09-01

    Full Text Available Study area is located in district of Bajestan and Ferdows cities, NE of Iran. Structurally, this area is part of Lut block. The oldest exposed rocks, to the north of intrusive rocks and in Eastern Bajestan, are meta-chert, slate, quartzite, thin-bedded crystalline limestone and meta-argillite. The sedimentary units are: Sardar Formation (Carboniferous, Jamal Formation (Permian, Sorkh Shale and Shotori Formations (Triassic, carbonateous rocks (Cretaceous and lithostratigraphically equivalent to Kerman conglomerate (Cretaceous-Paleocene are exposed in this area. Based on relative age, magmatism in eastern Bajestan and Taherabad started after Late Cretaceous and it has been active and repeated during Tertiary time. At least, three episodes of volcanic activities are recognized in this area. The first stage was mainly volcanic flow with mafic composition and minor intermediate. The second episode was mainly intermediate in composition. The third stage was changed to acid-intermediate in composition. Since the plutonic rocks intruded the volcanic rocks, therefore they may be Oligo-Miocene age. Bajestan intrusive rocks are granite-granodiorite-quartz monzonite. Taherabad intrusive rocks are diorite-quartz diorite- monzonite-latite. Bajestan intrusive rocks are reduced type (ilmenite series and Taherabad intrusive rocks are oxidized type (magnetite series.Based on geochemical analysis including trace elements, REE and isotopic data, Bajestan intrusive rocks formed in continental collision zone and the magma has crustal origin. Taherabad intrusive rocks were formed in subduction zone and magma originated from oceanic crust. Taherabad intrusive rock has exploration potential for Cu-Au and pb.

  14. Conception and numerical prediction of geomechanical measurements related to a vertical mine-by-test at the Meuse/Haute-Marne URL

    International Nuclear Information System (INIS)

    Andra plans experiments in the Meuse/Haute-Marne Underground Laboratory in order to study the hydro-mechanical behaviour of the argillite. For example, REP experiment is a vertical mine-by-test aiming at characterizing the short and long term hydro-mechanical response to a shaft sinking. Displacements, deformations, and pore pressures will be monitored during the shaft sinking. Andra and INERIS consider to back-analyse recorded data based on under-excavation method in order to estimate field stresses. The under-excavation technique consists in determining the pre-existing stress tensor in a relatively large rock volume from the global inversion of strain and displacement measurements recorded by numerous instruments during the disturbance of the medium (typically the excavation of an underground opening. This inversion requires several assumptions whose principal one is the quasi linear elastic behaviour of the rock mass. Background literature and field experimentations show both this technique as very promising but also the need for establishing its sensitivity to the principal assumptions needed. In the framework of a numerical sensitivity study of the under-excavation technique, aimed at testing most of the assumptions, input data and uncertainties to be encountered on the field, the 3D modelling (F1ac3D ) of a step-by-step vertical mine-by-test, based on REP design, has been set up and run in order to: I- calculate all numerical matrices needed 2- validate specific numerical developments implemented in SYTGEOmath. One major step of this study is to calculate each instrument response, coming up with a step-by-step strain or displacement curve versus the advancement of the shaft sinking. We assumed an experimental device based on 3 CSIRO cells, 3 multipoint extensometers and 1 multipoint inclinometer. (authors)

  15. Design cost scoping studies. Nevada Test Site Terminal Waste Storage Program, Subtask 1.3: facility hardening studies

    International Nuclear Information System (INIS)

    As part of a program being conducted by the U.S. Department of Energy, Nevada Operations Office, to determine the feasibility of establishing a terminal waste storage repository at the Nevada Test Site, URS/John A. Blume and Associates, Engineers, made approximate determinations of the additional costs required to provide protection of structures against seismic forces. A preliminary estimate is presented of the added costs required to harden the surface structures, underground tunnels and storage rooms, and vertical shafts of the repository against ground motion caused by earthquakes and underground nuclear explosions (UNEs). The conceptual design of all of the structures was adapted from proposed bedded-salt waste-isolation repositories. Added costs for hardening were calculated for repositories in three candidate geological materials (Eleana argillite, Climax Stock granite, and Jackass Flats tuff) for several assumed peak ground accelerations caused by earthquakes (0.3g, 0.5g, and 0.7g) and by UNEs (0.5g, 0.7g, and 1.0g). Hardening procedures to protect the tunnels, storage rooms, and shafts against incremental seismic loadings were developed from (1) qualitative considerations of analytically determined seismic stresses and (2) engineering evaluations of the dynamic response of the rock mass and the tunnel support systems. The added costs for seismic hardening of the surface structures were found to be less than 1% of the estimated construction cost of the surface structures. For the underground structures, essentially no hardening was required for peak ground accelerations up to 0.3g; however, added costs became significant at 0.5g, with a possible increase in structural costs for the underground facilities of as much as 35% at 1.0g

  16. Summary of national and international fuel cycle and radioactive waste management programs, 1984

    International Nuclear Information System (INIS)

    Worldwide activities related to nuclear fuel cycle and radioactive waste management programs are summarized. Several trends have developed in waste management strategy: All countries having to dispose of reprocessing wastes plan on conversion of the high-level waste (HLW) stream to a borosilicate glass and eventual emplacement of the glass logs, suitably packaged, in a deep geologic repository. Countries that must deal with plutonium-contaminated waste emphasize pluonium recovery, volume reduction and fixation in cement or bitumen in their treatment plans and expect to use deep geologic repositories for final disposal. Commercially available, classical engineering processing are being used worldwide to treat and immobilize low- and intermediate-level wastes (LLW, ILW); disposal to surface structures, shallow-land burial and deep-underground repositories, such as played-out mines, is being done widely with no obvious technical problems. Many countries have established extensive programs to prepare for construction and operation of geologic repositories. Geologic media being studied fall into three main classes: argillites (clay or shale); crystalline rock (granite, basalt, gneiss or gabbro); and evaporates (salt formations). Most nations plan to allow 30 years or longer between discharge of fuel from the reactor and emplacement of HLW or spent fuel is a repository to permit thermal and radioactive decay. Most repository designs are based on the mined-gallery concept, placing waste or spent fuel packages into shallow holes in the floor of the gallery. Many countries have established extensive and costly programs of site evaluation, repository development and safety assessment. Two other waste management problems are the subject of major R and D programs in several countries: stabilization of uranium mill tailing piles; and immobilization or disposal of contaminated nuclear facilities, namely reactors, fuel cycle plants and R and D laboratories

  17. Clay 2001 dossier: progress report on feasibility studies and research into deep geological disposal of high-level, long-lived waste; Dossier 2001 argile: sur l'avancement des etudes et recherches relatives a la faisabilite d'un stockage de dechets a haute activite et a vie longue en formation geologique profonde

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-12-01

    A French Act of Parliament passed on 30 December 1991 set out the main areas of research required to prepare solutions for the long-term management of high-level, long-lived radioactive waste. The three avenues of research listed in the Act included a feasibility study of the deep geological disposal of these waste, with responsibility for steering the study given to ANDRA, France National Agency for Radioactive Waste Management. Following government decisions taken in 1998, the study focused on two types of geological medium, clay and granite. The clay formations study is essentially based on results from an underground laboratory sited at the border between the Meuse and Haute-Marne departments, where the Callovo-Oxfordian argillite beds are being investigated. No site has yet been chosen for an underground laboratory for the granite study, so for the time being this will draw on generic work and on research carried out in laboratories outside France. ANDRA has decided to present an initial report on the results of its research programme, publishing a dossier on the work on clay formations in 2001 with a second dossier covering the work on granite due for release in 2002. This dossier is thus a review of the work carried out by ANDRA on the feasibility study into a radioactive waste repository in a clay formation. It represents one step in a process of studies and research work leading up to the submission of a report due in 2005 containing ANDRA conclusions on the feasibility of a repository in the clay formation. (author)

  18. Pedogenetic processes and carbon budgets in soils of Queretaro, Mexico

    Science.gov (United States)

    García Calderón, Norma Eugenia; Fuentes Romero, Elizabeth; Hernandez Silva, Gilberto

    2014-05-01

    Pedogenetic processes have been investigated in two different physiographic regions of the state of Querétaro in order to assess the carbon budget of soils, looking into the gains and losses of organic and inorganic carbon: In the mountain region of the natural reserve Sierra Gorda (SG) with soils developed on cretaceous argillites and shales under sub-humid temperate to semi-arid conditions, and in the Transmexican Volcanic Belt (TMVB) with soils developed on acid and intermediate igneous rocks under humid temperate climate in the highlands and semi-arid and subhumid subtropical conditions in the lowlands. The analyses of soil organic carbon (SOC) and soil inorganic carbon (SIC) of the SG region, including additional physical, chemical and mineralogical investigations were based on 103 topsoils in an area of 170 km2. The analyses in the TMVB region were based on the profiles of a soil toposequence from high mountainous positions down to the plains of the lowlands. The results show a SOC accumulation from temperate to semi-arid forest environments, based on processes of humification and clay formation including the influence of exchangeable Ca and the quantity and quality of clay minerals. The turnover rates of SOC and SIC depended largely on the rock parent materials, especially the presence of carbonate rocks. Moreover, we found that the SOC content and distribution was clearly depending on land use, decreasing from forests to agricultural land, such as pasture and cropping areas and were lowest under mining sites. The highest SIC pools were found in accumulation horizons of soils under semi-arid conditions. On all investigated sites SOC decreased the mobility of cations and especially that of heavy metals, such as As, Hg, Sb, Pb, and Cd.

  19. Advice of the French institute of radiation protection and nuclear safety about the 'Clay 2005' file

    International Nuclear Information System (INIS)

    The French institute of radiation protection and nuclear safety (IRSN) presents in this document its evaluation of the 'Clay 2005' file made by the ANDRA and which aims at demonstrating the feasibility of a disposal facility for high level and long living rad-wastes in the argillite formation of the Bure site. The critical points of the safety have been considered more thoroughly, together with the uncertainties concerning some important data and phenomena in relation with the confining properties of such a disposal facility. The basic geologic data gathered by the ANDRA about the Callovo-Oxfordian clay formation of the Bure site are sufficient to confirm the favorable intrinsic properties of this formation with respect to the confinement of wastes. The main possible disturbances of internal and external origin (thermal, hydrological, mechanical, chemical, climatic change, earthquakes, erosion..) would have no redhibitory impact on the overall confining capacity of the facility. The design safety principles retained for the exploitation of the facility and the post-closure safety aspects are globally satisfactory. Therefore, the IRSN considers the disposal of rad-wastes in the Callovo-Oxfordian argilite formation as feasible but in the case of a continuation of this project, several complementary informations would have to be supplied in particular concerning: the possible fracturing of the host and surrounding formations, the possibility of localized inhomogeneous fluid flows inside the surrounding formations, the improvement of our knowledge about the changes of the mechanical, physical and chemical properties of the site rocks and of concretes with time, the dimensioning of the metallic components of the facility (shafts, containers..), and the efficiency of the ventilation system with respect to the explosion risks inside B-type waste alveoles. (J.S.)

  20. Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wen-Sheng [Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan (China); Liu, Chen-Wuing; Tsao, Jui-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan (China); Li, Ming-Hsu [Institute of Hydrological and Oceanic Sciences, National Central University, Jhongli, Taiwan (China)

    2012-07-01

    A proposed site for final disposal of low-level radioactive waste located in Daren Township of Taitung County along the southeastern coast has been on the selected list in Taiwan. The geology of the Daren site consists of argillite and meta-sedimentary rocks. A mined cavern design with a tunnel system of 500 m below the surface is proposed. Concrete is used as the main confinement material for the engineered barrier. To investigate the hydrogeochemical transport of radionuclides through engineered barriers system, HYDROGEOCHEM5.0 model was applied to simulate the complex chemical interactions among radionuclides, the cement minerals of the concrete, groundwater flow, and transport in the proposed site. The simulation results showed that the engineered barriers system with the side ditch efficiently drained the ground water and lowered the concentration of the concrete degradation induced species (e.g., hydrogen ion, sulfate, and chloride). The velocity of groundwater observed at side ditch gradually decreased with time due to the fouling of pore space by the mineral formation of ettringite and thaumasite. The short half-life of Co-60, Sr-90 and Cs-137 significantly reduced the concentrations, whereas the long half-life of I-129(1.57x10{sup 7} years) and Am-241(432 years) remain stable concentrations at the interface of waste canister and concrete barrier after 300 years. The mineral saturation index (SI) was much less than zero due to the low aqueous concentration of radionuclide, so that the precipitation formation of Co-60, Sr-90, I-129, Cs-137 and Am-241 related minerals were not found. The effect of adsorption/desorption (i.e., surface complexation model) could be a crucial geochemical mechanism for the modeling of liquid-solid phase behavior of radionuclide in geochemically dynamic environments. Moreover, the development of advanced numerical models that are coupled with hydrogeochemical transport and dose assessment of radionuclide is required in the future

  1. Gold mineralisation near the Main Divide, upper Wilberforce valley, Southern Alps, New Zealand

    International Nuclear Information System (INIS)

    Veins up to 8 m wide fill extensional fractures in Torlesse Terrane metasediments near the Main Divide in the upper Wilberforce valley, Canterbury, New Zealand. The upper Wilberforce veins are part of a prominent 40 km long, NNE-trending swarm of gold-bearing veins formed across the Main Divide during the Late Cenozoic rise of the Southern Alps. The veins occur within, and near, a prominent set of faults which constitute the Main Divide Fault Zone. The veins are irregular in shape due to contrasting host rock properties, and have been only weakly sheared and deformed. Veins cut across greywacke beds and follow irregularly along argillite beds, on the 1-10 m scale. Quartz dominates vein mineralogy, but albite forms up to 45% of some veins, and minor chlorite, pyrite, arsenopyrite, chalcopyrite, and gold occur sporadically, especially in breccias near vein margins. Fluid inclusions in vein quartz homogenise at 180-253 degrees C, and arsenopyrite composition (28.3-30.8 at.% As) suggest formation temperatures of 250-350 degrees C. Elevated arsenic levels (up to 200 ppm above a background of 10 ppm) in some host greywackes and argellites suggest that hydrothermal activity pervaded host rocks as well as forming veins, but there is no textural evidence for this fluid flow. Late-stage carbonates in faults adjacent to the quartz veins, but which postdate the quartz veins, have δ18O ranging from 11.1 to 25.6 per thousand, and δ13C ranging from -12.5 to -1.1 per thousand. These carbonates were deposited by a mixture of meteoric and crustally isotopically exchanged fluid as a shallow-level manifestation of the same hydrothermal system which deposited the quartz veins. The upper Wilberforce veins structurally and mineralogically resemble some Late Cenozoic gold-bearing vein systems in the Mt Cook area, 100 km to the southwest along the Southern Alps. (author). 52 refs., 9 figs., 3 tabs

  2. Two-stage structural development of a Paleozoic auriferous shear zone at the Globe-Progress deposit, Reefton, New Zealand

    International Nuclear Information System (INIS)

    The Globe-Progress gold deposit at Reefton is hosted in a curvilinear mineralised zone that cuts Paleozoic Greenland Group basement metagreywackes. Two discrete phases of mineralisation have resulted in the formation of five different ore types along the shear. An initial phase of mineralisation formed hydrothermal quartz veins and associated Au, As, and S enrichment, with low-grade mineralised host rock. These quartz veins and mineralised host rocks form the outer regions of the mineralised zone. A second hydrothermal phase introduced Sb, Au, As, and S during brittle shear deformation focused on the pre-existing mineralised rocks. This deformation and mineralisation resulted in the formation of metre-scale cataclasite ore and quartz breccia from mineralised host rock and hydrothermal quartz veins, respectively. Cataclasite was derived from argillite layers in the host rock, from which Na, Fe, and Mg have been leached during mineralisation; Al, Ti, and Cr have been conserved; and there has been minor enrichment in Sr, Pb, Zn, and Cu. No quartz was added to the cataclasite or quartz breccia during mineralisation, but some quartz recrystallisation occurred locally, and quartz clasts were physically incorporated into the cataclasite during deformation. The presence of euhedral sulfides in the cataclasite (40% of total sulfides), late-stage undeformed stibnite veins infilling breccia (1-5 cm3 scale), and undeformed free gold in quartz breccia, imply that the second phase of mineralisation persisted both during and after cataclasis and brecciation. Antimony deposition is greatest in the central cataclasite, up to 6 wt%, and locally in the quartz breccia where stibnite veins are present. Concentrations of Sb decrease with distance from the shear zone. The second, Sb-rich phase of mineralisation in the Globe-Progress deposit resembles similar Sb-rich overprints in the correlative Victorian goldfield of Australia. (author). 38 refs., 10 figs., 1 tab.

  3. A closely-spaced magnetotelluric study of the Ahuachapan-Chipilapa geothermal field, El Salvador

    Energy Technology Data Exchange (ETDEWEB)

    Romo, Jose Manuel; Flores, Carlos; Vega, Raymundo; Vazquez, Rogelio; Flores, Marco A. Perez; Trevino, Enrique Gomez; Esparza, Francisco J.; Garcia, Victor H. [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Baja California (Mexico); Quijano, Julio E. [Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL), Santa Tecla (El Salvador)

    1997-12-01

    The distribution of electrical conductivity beneath the Ahuachapan-Chipilapa geothermal area was simulated using 2-D models based on 126 closely-spaced magnetotelluric (MT) measurements. The observed MT response was interpreted as being produced by the superposition of two orthogonal geological structural systems: an approximately E-W regional trend associated with the Central Graben structure, which affects the loner period response, and a local and younger N-S fault system that is responsible for the short-to-intermediate period data. The MT response in the 0.02-10 s range period was used to simulate the conductivity structure within the first 2 km depth. By correlating the low-resistivity zones between twelve 2-D models, maps of the spatial distribution of conductors at three different depth levels were constructed. Three deep conductors were identified, one of the associated with the Ahuachapan reservoir, another apparently related to the Laguna Verde volcano, and a third one controlled by El Tortuguero Graben. The subsurface geometry of these conductivity anomalies suggests that the the Chipilapa and La Labor hot springs are supplied by two separate sources of hot fluids, one coming from the east and the other from the south or southwest. The distribution of the shallow high-conductivity zones agrees with the hydrothermal alteration zones mapped at the surface, suggesting that at shallow levels the argillitization process contributes significantly to the low resistivity. The large number of drillholes and the dense MT site coverage allowed the definition of important correlations between high temperatures and high conductivity, as well as between deep conductivity anomalies and productive wells. On this basis two years for future drilling are proposed. (Author)

  4. Seismic properties and effects of hydrothermal alteration on Volcanogenic Massive Sulfide (VMS) deposits at the Lalor Lake in Manitoba, Canada

    Science.gov (United States)

    Miah, Khalid H.; Bellefleur, Gilles; Schetselaar, Ernst; Potter, David K.

    2015-12-01

    Borehole sonic and density logs are essential for mineral exploration at depth, but its limited availability to link rock properties of different ore forming geologic structure is a hindrance to seismic data interpretations. In situ density and velocity logs provide first order control on the reflectivity of various lithologic units. We analyzed borehole logs from 12 drill holes over and around the Lalor VMS deposits geographically located in the northern Manitoba, Canada, in an attempt to characterize lithologic units based on its seismic properties. The Lalor Lake deposit is part of the Paleoproterozoic Flin Flon Belt, and associated with an extensive hydrothermal alteration system. Volcanogenic Massive Sulfide (VMS) zones are distributed in several ore lenses with relatively shallower facies comprise solid to solid sulfides, tend to be disseminated or Stringer sulfides, while deeper lenses are gold and silver enriched and occurred in the highly altered footwall region. Our analysis suggests that massive sulfide and diorite have higher acoustic impedance than other rock units, and can produce useful reflection signatures in seismic data. Bivariate distributions of P-wave velocity, density, acoustic impedance and Poisson's ratio in end-member mineral cones were used for qualitative assessment of the extent of alteration of various lithologic units. It can be inferred that hydrothermal alteration has considerably increased P-wave velocity and density of altered argillite and felsic volcanic rocks in comparison to their corresponding unaltered facies. Amphibole, garnet, kyanite, pyrite, sphalerite and staurolite are the dominant end-member alteration minerals affecting seismic rock properties at the VMS site.

  5. Modeling of excavation induced coupled hydraulic-mechanical processes in claystone

    Energy Technology Data Exchange (ETDEWEB)

    Massmann, Jobst

    2009-07-01

    Concepts for the numerical modeling of excavation induced processes in claystone are investigated. The study has been motivated by the international discussion on the adequacy of claystone as a potential host rock for a final repository of radioactive waste. The processes, which could impact the safety of such a repository, are manifold and strongly interacting. Thus, a multiphysics approach is needed, regarding solid mechanics and fluid mechanics within a geological context. A coupled modeling concept is therefore indispensable. Based on observations and measurements at an argillaceous test site (the underground laboratory Tournemire, operated by the Institute of Radioprotection and Nuclear Safety, France) the modeling concept is developed. Two main processes constitute the basis of the applied model: deformation (linear elasticity considering damage) and fluid flow (unsaturated one-phase flow). Several coupling phenomena are considered: Terzaghi 's effective stress concept, mass conservation of the liquid in a deformable porous media, drying induced shrinkage, and a permeability which depends on deformation and damage. In addition, transversely isotropic material behavior is considered. The numerical simulations are done with the finite element code RockFlow, which is extended to include: an orthotropic non-linear shrinkage model, a continuum damage model, and an orthotropic permeability model. For these new methods the theory and a literature review are presented, followed by applications, which illustrate the capability to model excavation induced processes in principle. In a comprehensive case study, the modeling concept is used to simulate the response of the Tournemire argillite to excavation. The results are compared with observations and measurements of three different excavations (century old tunnel, two galleries excavated in 1996 and 2003). In summary, it can be concluded that the developed model concept provides a prediction of the excavation

  6. Preliminary basin analysis of late Proterozoic-Cambrian post-rift strata, southeast Idaho thrust belt

    Energy Technology Data Exchange (ETDEWEB)

    Link, P.K.; Jansen, S.T.; Halimdihardja, P.; Lande, A.C.; Zahn, P.D.

    1987-08-01

    Strata of the Brigham Group in the Paris-Putnam plate of the southeastern Idaho thrust belt span the late Proterozoic-Cambrian boundary and consist of quartzose sandstone with subordinate pebble conglomerate and siltstone. The Brigham Group is overlain by fossiliferous Cambrian carbonate units that represent the transition from siliciclastic to carbonate deposition in the Cordilleran miogeocline. The Brigham Group contains four stratigraphic sequences bounded by regional disconformities. The lower sequence includes strata below the Brigham group (upper member, Pocatello Formation), plus the Papoose Creek Formation and most of the overlying Caddy Canyon Quartzite. This sequence is dominantly marine with shoreface and braided fluvial strata at the top. The first sequence is overlain disconformably by offshore sub-wave base marine strata of the upper Caddy Canyon Quartzite and Inkom Formation. This second sequence is entirely marine and is composed dominantly of siltstone with sandstone-filled channels. The third sequence comprises the Mutual Formation, an entirely braided fluvial and lacustrine unit. The fourth sequence (Sauk sequence) locally overlies the Mutual Formation with an erosional unconformity and consists of dominantly marine strata of the Camelback Mountain Quartzite, Gibson Jack Formation, Windy Pass Argillite, Twin Knobs Formation, and Sedgwick peak Quartzite. Correlations of these sequences to the McCoy Creek Group of eastern Nevada suggests uniform conditions of sea level and subsidence across the late Proterozoic-Cambrian Cordilleran miogeocline. This preliminary synthesis suggests the Brigham and McCoy Creek Groups are post-rift deposits, as indicated by regional persistence of facies, paleocurrents, and quartzose petrology.

  7. Modeling of excavation induced coupled hydraulic-mechanical processes in claystone

    International Nuclear Information System (INIS)

    Concepts for the numerical modeling of excavation induced processes in claystone are investigated. The study has been motivated by the international discussion on the adequacy of claystone as a potential host rock for a final repository of radioactive waste. The processes, which could impact the safety of such a repository, are manifold and strongly interacting. Thus, a multiphysics approach is needed, regarding solid mechanics and fluid mechanics within a geological context. A coupled modeling concept is therefore indispensable. Based on observations and measurements at an argillaceous test site (the underground laboratory Tournemire, operated by the Institute of Radioprotection and Nuclear Safety, France) the modeling concept is developed. Two main processes constitute the basis of the applied model: deformation (linear elasticity considering damage) and fluid flow (unsaturated one-phase flow). Several coupling phenomena are considered: Terzaghi 's effective stress concept, mass conservation of the liquid in a deformable porous media, drying induced shrinkage, and a permeability which depends on deformation and damage. In addition, transversely isotropic material behavior is considered. The numerical simulations are done with the finite element code RockFlow, which is extended to include: an orthotropic non-linear shrinkage model, a continuum damage model, and an orthotropic permeability model. For these new methods the theory and a literature review are presented, followed by applications, which illustrate the capability to model excavation induced processes in principle. In a comprehensive case study, the modeling concept is used to simulate the response of the Tournemire argillite to excavation. The results are compared with observations and measurements of three different excavations (century old tunnel, two galleries excavated in 1996 and 2003). In summary, it can be concluded that the developed model concept provides a prediction of the excavation induced

  8. Rotational Remanent Magnetization (RRM) to Identify Pyrrhotite in Natural Iron-Sulfide-Bearing Samples

    Science.gov (United States)

    Slotznick, S. P.; Kirschvink, J. L.; Fischer, W. W.; Webb, S. M.

    2014-12-01

    Pyrrhotite has been known for several decades to have anomalous demagnetization behavior when using tumbling AF techniques. This was quantified by Thomson (1990) to show that pyrrhotite can acquire rotational remanent magnetization (RRM) similar to the more intensely-studied iron sulfide, greigite. Use of RRM as an identification tool in natural samples has not become standard practice, perhaps due to the decrease in use of tumbling AF techniques. However, using the 2G SQuID magnetometer with in-line AF/ARM coils and RAPID automated protocols (Kirschvink et al. 2008), one can easily produce and measure RRM. This method of measuring RRM has been used to identify greigite (Suzuki et al. 2006), but not pyrrhotite. We present room temperature RRM measurements for samples spinning from -20 to +20 rev/sec, perpendicular to peak AF fields of 90mT (at 950 Hz) in iron-sulfide-bearing shales, argillites, and carbonates throughout Earth History (Miocene, Cretaceous, Mesoproterozoic, Late Archean). Presence of pyrrhotite was confirmed using AF demagnetization of NRM (GRM), IRM acquisition/AF demagnetization (Cisowski plots), Kappabridge thermal susceptibility, ultra-high resolution scanning SQuID microscopy (UHRSSM), and/or X-ray absorption near edge spectroscopy (XANES)/multiple energy X-ray fluorescence (XRF) imaging. Although the total absence of pyrrhotite cannot be proven, the same techniques were applied to rocks that do not gain RRM easily to identify their iron sulfides and ferromagnetic minerals, and no magnetic iron sulfides were found. The RRM signal for pyrrhotite is distinct from that of greigite, suggesting it could be used as a tool for distinguishing these magnetic iron sulfides from each other. Further work on room temperature RRM could define a unique non-destructive rock magnetic test for pyrrhotite.

  9. Modeling of radionuclide migration through the geologic media. Application to the Meuse/Haute-Marne site in France

    International Nuclear Information System (INIS)

    In order to review ANDRA's modeling of a deep geological disposal of HLW in a clay formation located in the Meuse/Haute Marne area, IRSN has developed its own modeling methodology, based on three numerical models. A first 'host rock model', including a simplified repository design, is used to simulate the activity transport throughout the repository and the argillite host layer. The model aims at evaluating the role of components of the repository design, together with the host formation, on the activity transport. Then, a second 'hydrogeological model', set on hydrodynamic parameters measured in situ, allows the determination of possible water pathways, outlets and associated transfer times taking into account the possible hydraulic role of identified or postulated tectonic structures in the vicinity of the site. Several possible combinations for the hydraulic parameters (hydraulic conductivities and transmissivities) allow to fit the in situ measured hydraulic heads. The 'hydrogeological model' is finally coupled with a radionuclide 'transport model', devoted to simulate the transport of radionuclides out of the host rock to the outlets. Considering the uncertainties related to both advection and diffusion processes in the aquifers, a sensitivity analysis is carried out in order to assess its influence on the activity transport through the different layers above the host formation. Two specific outlets are considered: at the ground surface, a 'natural' outlet above the location of the repository system, and in the host rock's overlying aquifer, in a 'well drilling' zone. It is shown that the activity reaching the 'natural' outlet is mainly governed by diffusive fluxes whereas the activity reaching the 'well drilling' zone depends on the advective properties of the fault zones. The lesson learnt from this modeling is that the diffusion regime needs to be better quantified in order to discriminate the respective influence of both outlets. (authors)

  10. Modeling of oxygen gas diffusion and consumption during the oxic transient in a disposal cell of radioactive waste

    International Nuclear Information System (INIS)

    Highlights: • This paper deals with the geochemistry of underground HLW disposals. • The oxic transient is a key issue in performance assessment (e.g. corrosion, redox). • A reactive transport model is explicitly coupled to gas diffusion and reactivity. • Application to in situ experiment (Tournemire laboratory) and HLW disposal cell. • Extent of the oxidizing/reducing front is investigated by sensitivity analysis. - Abstract: The oxic transient in geological radioactive waste disposals is a key issue for the performance of metallic components that may undergo high corrosion rates under such conditions. A previous study carried out in situ in the argillite formation of Tournemire (France) has suggested that oxic conditions could have lasted several years. In this study, a multiphase reactive transport model is performed with the code HYTEC to analyze the balance between the kinetics of pyrite oxidative dissolution, the kinetics of carbon steel corrosion and oxygen gas diffusion when carbon steel components are emplaced in the geological medium. Two cases were modeled: firstly, the observations made in situ have been reproduced, and the model established was then applied to a disposal cell for high-level waste (HLW) in an argillaceous formation, taking into account carbon steel components and excavated damaged zones (EDZ). In a closed system, modeling leads to a complete and fast consumption of oxygen in both cases. Modeling results are more consistent with the in situ test while considering residual voids between materials and/or a water unsaturated state allowing for oxygen gas diffusion (open conditions). Under similar open conditions and considering ventilation of the handling drifts, a redox contrast occurs between reducing conditions at the back of the disposal cell (with anoxic corrosion of steel and H2 production) and oxidizing conditions at the front of the cell (with oxic corrosion of steel). The extent of the oxidizing/reducing front in the

  11. Clay 2001 dossier: progress report on feasibility studies and research into deep geological disposal of high-level, long-lived waste

    International Nuclear Information System (INIS)

    A French Act of Parliament passed on 30 December 1991 set out the main areas of research required to prepare solutions for the long-term management of high-level, long-lived radioactive waste. The three avenues of research listed in the Act included a feasibility study of the deep geological disposal of these waste, with responsibility for steering the study given to ANDRA, France National Agency for Radioactive Waste Management. Following government decisions taken in 1998, the study focused on two types of geological medium, clay and granite. The clay formations study is essentially based on results from an underground laboratory sited at the border between the Meuse and Haute-Marne departments, where the Callovo-Oxfordian argillite beds are being investigated. No site has yet been chosen for an underground laboratory for the granite study, so for the time being this will draw on generic work and on research carried out in laboratories outside France. ANDRA has decided to present an initial report on the results of its research programme, publishing a dossier on the work on clay formations in 2001 with a second dossier covering the work on granite due for release in 2002. This dossier is thus a review of the work carried out by ANDRA on the feasibility study into a radioactive waste repository in a clay formation. It represents one step in a process of studies and research work leading up to the submission of a report due in 2005 containing ANDRA conclusions on the feasibility of a repository in the clay formation. (author)

  12. Structural evolution of lamprophyric dikes in Lailai, northeastern coast of Taiwan, deduced from mesoscopic structures in dikes and country rocks

    Science.gov (United States)

    You, Cian-Siang; Huang, Wen-Jeng; Lo, Wei; Wang, Tzu-Bin; Chen, Chien-Chih

    2015-04-01

    Lamprophyric dikes are standing in right-stepping en echelon up to 2.3 meters high within the Oligocene Tatungshan formation on the Lai-Lai wave-cut platform in the northeastern coast of Taiwan. The marine platform composed mainly of argillite is the extension of Hsuehshan range, which has the tallest peak of 3,886 m high in Taiwan. The dikes formed at depth in the late Miocene of 9±1.1 Ma ago are exposed on the marine platform nowadays due to the exhumation and Penglai orogeny resulting from the collision of Eurasian plate and Philippine Sea plate, which began in Pleistocene of 5-6 Ma ago. In consequence, folds, faults, joints and other structures are associated with them. In this study, the distribution of the dikes and fractures were mapped by conducting accurate surveys with a total station theodolite and orthorectifying aerial images taken by an unmanned aerial vehicle in different elevations. Electrical resistivity exploration was performed to decipher the arrangement of the dikes underground and the characteristics of the faults. The associated mesoscopic structures were delineated by mapping at a scale of 1: 40 in the field. We infer that the dikes was formed at depth of approximately 2.4 kilometers according to the thickness of overlaying sedimentary rocks formed from late Oligocene to late Miocene. Thus, it excludes the possibility that fractures existed before the lamprophyric magma intruded into the country rocks. Our observations help restore the original status of the current 19 dike segments. We conclude that the lamprophyric magma forcedly and vertically intruded into the Oligocene rocks and the direction change of maximum principle stress at depth of 2.4 kilometers resulted in three or more right-stepping en-echelon dikes.

  13. Geochemistry and mineralogy

    Energy Technology Data Exchange (ETDEWEB)

    Plecas, I.; Dimovic, S.; Orta, M.M.; Alba, M.D.; Alvero, R.; Becerro, A.I.; Castro, M.A.; Chain, P.; Escudero, A.; Naranjo, M.; Pavon, E.; Trillo, J.M.; Vejsada, J.; Vokal, A.; Zadvernyuk, H.P.; Fedorenko, Y.G.; Zlobenko, B.P.; Koromyslichenko, T.I.; Battaglia, S.; Cervelli, M.; Millot, R.; Girard, J.P.; Missana, T.; Garcia-Gutierrez, M.; Alonso, U.; Muurinen, A.; Carlsson, T.; Chain, P.; Alba, M.D.; Becerro, A.I.; Castro, M.A.; Escudero, A.; Gonzalez-Carrascosa, T.; Hurtado, S.; Pavon, E.; Villa, M.; Bourg, I.C.; Sposito, G.; Bourg, A.C.M.; Marques Fernandes, M.; Rabung, Th.; Dahn, R.; Baeyens, B.; Bradbury, M.H.; Breynaert, E.; Maes, A.; Bruggeman, C.; Maes, I.A.; Vancluysen, J.; Credoz, A.; Bildstein, O.; Jullien, M.; Raynal, J.; Petronin, J.C.; Trotignon, L.; Pokrovsky, O.; Jacquier, P.; Beaucaire, C.; Vuillaume, A.L.; Wittebroodt, Ch.; Ly, J.; Page, J.; Savoye, S.; Pitsch, H.; Jacques, D.; Wang, L.; Galunin, E.; Chain, P.; Alba, M.D.; Vidal, M.; Grandia, F.; Domenech, C.; Arcos, D.; Duro, L.; Bruno, J.; Andre, L.; Pauwels, H.; Azaroual, M.; Albrecht, A.; Romero, M.A.; Aerts, S.; Boven, P.; Van Geet, M.; Boever, P. de; Alonso, U.; Albarran, N.; Missana, T.; Garcia-Gutierrez, M.; Truche, L.; Berger, G.; Guillaume, D.; Jacquot, E.; Tournassat, Ch.; Lerouge, C.; Brendle, J.; Greneche, J.M.; Touzelet, St.; Blanc, Ph.; Gaucher, E.C.; Thoenen, T.; Klinkenberg, M.; Kaufhold, S.; Dohrmann, R.; Siegesmund, S.; Liu, D.J.; Bruggeman, C.; Maes, N.; Weber, T.; Trotignon, L.; Pozo, C.; Bildstein, O.; Combarieu, G. de; Frugier, P.; Menut, D

    2007-07-01

    This session gathers 52 articles (posters) dealing with: the influence of natural sorbents immobilization of spent ion exchange resins in cement; the chemical stability of rare-earth silicate; the mineralogical heterogeneity of Rokle bentonite and radionuclide adsorption: A case study for cesium; the rheological and sorption properties of clay-polymer composites; the clay mineral interactions with leachate solutions in landfills; the lithium isotope fractionation during adsorption onto mineral surfaces; the sorption of Sr{sup 2+} onto mixed smectite / illite clays; Eh and pH in the pore water of compacted bentonite; the chemical interaction of {sup 152}Eu with the clay barrier; the modeling of the acid-base surface chemistry of Montmorillonite; a time resolved laser fluorescence and X-ray absorption spectroscopy study of lanthanide/actinide sorption on clay minerals: influence of carbonate complexation; the structure elucidation and occurrence of Tc(IV) pyrogallol complexes; the geochemistry of Se(0) under boom clay conditions; an experimental and modelling study of pure secondary silicate minerals reactivity in geological CO{sub 2} sequestration conditions; an experimental evaluation of a retention model for major groundwater elements on the Tournemire argillite; modelling the long term interaction of cementitious pore water with Boom clay; the sorption-desorption of radionuclides and analogues in clays suitable for barriers; the modelling of the Redox evolution in the tunnel backfill of a high level nuclear waste repository; the reactivity of nitrates in the different storage compartments of type-b wastes; an investigation into the biodiversity of sulphate reducing bacteria in Boom clay; the colloid generation mechanisms from compacted bentonite under different geochemical conditions; the experimental reduction of aqueous sulphate by hydrogen in the context of the Callovo-Oxfordian argillite; cation exchanged Fe(II) and Sr as compared to other divalent cations

  14. DECOVALEX-THMC Project. Task C. Excavation Damaged Zone (EDZ) in argillaceous rock at Tournemire site (France). Report of Task C1

    International Nuclear Information System (INIS)

    rocks and in particular the stress field, mechanical properties and hydraulic properties. Thereafter, the EDZ characterization from geological mapping and permeability measurements are presented. The EDZ in the 100 years old tunnel drilled manually and with its reinforcement of limestone blocks is very different from the EDZ observed in drifts excavated with road-headers 3 and 10 years ago. Numerical models have to be developed to predict the extent of the EDZ around the tunnel. The CEA/IRSN team contribution to Task C1 concerns three calculations: a pure mechanical calculation, a coupled hydro-mechanical calculation with saturated rock, and coupled hydro-mechanical calculation with unsaturated rock. The EDZ around the tunnel has been estimated on the basis of a post-processing of the stress calculations, using Mohr-Coulomb failure criterion. These calculations were performed by using the CEA finite element code CASTEM, which can simulate fully coupled THM processes. All the results from the calculations show that an EDZ around the tunnel can only be predicted if we consider mechanical rock properties lower than those measured in laboratory. However, none of the predictions provided the shape and the real extent of the observed EDZ in the tunnel. The evaluation of the EDZ by a simple post-processing technique does not account for the irreversible effect of damage on the mechanical as well as hydraulic behaviour of the argillite. The ISEB/BGR team performed the simulations by using the finite element code Rock Flow. The team simulated three cases where the influence of capillary pressure shows that a change of saturation at the boundary of the tunnel influences an area around the tunnel with time. In the near field of the tunnel, the effect of seasonal fluctuation is high. This result is influenced by the boundary conditions, the permeability and the relation between the capillary pressure and the saturation. Case 2 incorporates the swelling or shrinking of the argillite

  15. Geochemistry and mineralogy

    International Nuclear Information System (INIS)

    This session gathers 52 articles (posters) dealing with: the influence of natural sorbents immobilization of spent ion exchange resins in cement; the chemical stability of rare-earth silicate; the mineralogical heterogeneity of Rokle bentonite and radionuclide adsorption: A case study for cesium; the rheological and sorption properties of clay-polymer composites; the clay mineral interactions with leachate solutions in landfills; the lithium isotope fractionation during adsorption onto mineral surfaces; the sorption of Sr2+ onto mixed smectite / illite clays; Eh and pH in the pore water of compacted bentonite; the chemical interaction of 152Eu with the clay barrier; the modeling of the acid-base surface chemistry of Montmorillonite; a time resolved laser fluorescence and X-ray absorption spectroscopy study of lanthanide/actinide sorption on clay minerals: influence of carbonate complexation; the structure elucidation and occurrence of Tc(IV) pyrogallol complexes; the geochemistry of Se(0) under boom clay conditions; an experimental and modelling study of pure secondary silicate minerals reactivity in geological CO2 sequestration conditions; an experimental evaluation of a retention model for major groundwater elements on the Tournemire argillite; modelling the long term interaction of cementitious pore water with Boom clay; the sorption-desorption of radionuclides and analogues in clays suitable for barriers; the modelling of the Redox evolution in the tunnel backfill of a high level nuclear waste repository; the reactivity of nitrates in the different storage compartments of type-b wastes; an investigation into the biodiversity of sulphate reducing bacteria in Boom clay; the colloid generation mechanisms from compacted bentonite under different geochemical conditions; the experimental reduction of aqueous sulphate by hydrogen in the context of the Callovo-Oxfordian argillite; cation exchanged Fe(II) and Sr as compared to other divalent cations (Ca, Mg) in the

  16. DECOVALEX-THMC Project. Task C. Excavation Damaged Zone (EDZ) in argillaceous rock at Tournemire site (France). Report of Task C1

    Energy Technology Data Exchange (ETDEWEB)

    Rejeb, A. (comp.) [Inst. of Radioprotection and Nuclear Safety (France); Stephansson, O. (comp.) [GeoForschungsZentrum-Potsdam (Germany); Millard, A. [CEA/IRSN (France); Ziefle, G.; Kohlmeier, M.; Massmann, J.; Zielke, W. [ISEB/BGR (Germany); Uehara, S.; Kobayashi, A.; Chijimatsu, M.; Fujita, T. [KU/JAEA (Japan)

    2007-02-15

    rocks and in particular the stress field, mechanical properties and hydraulic properties. Thereafter, the EDZ characterization from geological mapping and permeability measurements are presented. The EDZ in the 100 years old tunnel drilled manually and with its reinforcement of limestone blocks is very different from the EDZ observed in drifts excavated with road-headers 3 and 10 years ago. Numerical models have to be developed to predict the extent of the EDZ around the tunnel. The CEA/IRSN team contribution to Task C1 concerns three calculations: a pure mechanical calculation, a coupled hydro-mechanical calculation with saturated rock, and coupled hydro-mechanical calculation with unsaturated rock. The EDZ around the tunnel has been estimated on the basis of a post-processing of the stress calculations, using Mohr-Coulomb failure criterion. These calculations were performed by using the CEA finite element code CASTEM, which can simulate fully coupled THM processes. All the results from the calculations show that an EDZ around the tunnel can only be predicted if we consider mechanical rock properties lower than those measured in laboratory. However, none of the predictions provided the shape and the real extent of the observed EDZ in the tunnel. The evaluation of the EDZ by a simple post-processing technique does not account for the irreversible effect of damage on the mechanical as well as hydraulic behaviour of the argillite. The ISEB/BGR team performed the simulations by using the finite element code Rock Flow. The team simulated three cases where the influence of capillary pressure shows that a change of saturation at the boundary of the tunnel influences an area around the tunnel with time. In the near field of the tunnel, the effect of seasonal fluctuation is high. This result is influenced by the boundary conditions, the permeability and the relation between the capillary pressure and the saturation. Case 2 incorporates the swelling or shrinking of the argillite

  17. 234U/238U - δ7Li - δ11B isotope systematics on aquifer groundwaters from deep scientific boreholes from the Meuse-Haute Marne site. Preliminary results

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Groundwater data have been acquired all around the Underground Research Laboratory, in deep boreholes, to determine the origin and residence time of water circulations in limestones of Oxfordian and Dogger age, surrounding the Callovo-Oxfordian argillites, and to determine the hydrogeologic role of the argillites regarding aquifers. In this work, U, Li and B isotopes have been analyzed in the framework of two research projects funded by BRGM and ANDRA (projects IsoBLiFe and BULiTh). In the Meuse/Haute-Marne area, the Dogger and Oxfordian limestones have a very weak permeability and pass through a free aquifer flow regime in the southeastern part where they join the captive underground aquifer in the centre and Northwest. Most U activity ratios are lower than the secular equilibrium value, especially for Oxfordian waters that may be very depleted in 234U (with activity ratios as low as 0.54), whereas Dogger groundwaters are on average closer to the equilibrium. In addition, U concentrations are generally lower in Dogger groundwaters. For Dogger groundwaters, iso-value (activity) curves follow approximately a NE-SW axis, parallel to both outcropping areas of Dogger limestones (∼ 30-35 km East of the Bure region) and the Gondrecourt Graben. This is compatible with a downflow return-to-equilibrium through time, but the lower activity ratios (close to 0.8) measured West of the Graben (on a Joinville - Commercy line) show that other processes have to be involved to explain U data. These lower activities might result from water-rock interaction processes and/or from an input of waters very depleted in 234U, which would 'contaminate' the Dogger groundwaters. In contrast, U activities measured in Oxfordian groundwaters cannot be explained a priori by any process of downflow return-to-equilibrium, as the recharge zone is located a few km East to the study area. Indeed, U activity iso-value curves follow a

  18. Comparison of Acoustic Energy Meter (AEM) and Schmidt hammer 'R' for rapid assessment of rock surface hardness: a preliminary assessment from southeast Queensland, Australia

    Science.gov (United States)

    Brook, Martin; Winkler, Stefan

    2015-04-01

    This research focuses on one of the key challenges in geomorphology - quantifying rock surface hardness via in situ measurements, to provide information on rock physical properties. This has been a focus in recent years with the rapid emergence of studies that center on surface and near surface weathering impacts, and rates of material loss. Indeed, a key element to understanding how weathering and erosion processes combine to influence rock surface (and landscape) evolution is the measurement and monitoring of rock surface hardness. We provide results from a preliminary assessment of the applicability of the Acoustic Energy Meter (AEM) to subaerial rock surface hardness, in comparison with an N-Type Schmidt hammer. The AEM apparatus consists of a geophone which is in contact with the rock surface and some electronics. The AEM is held normal to the surface to be tested and the surface is struck with a small hammer (typically 0.75 kg), with the AEM quantifying the decay time of seismically-induced oscillations within the top c. 1-2 m of the rock mass. Previous work using an AEM has focused on measuring roof stability and delamination in South African underground coal, gold and platinum mines, where long AEM reverberation times correlated well with weak rock mass and dense microfracturing. However, the technique has rarely been applied to the assessment of rock surfaces in a subaerial setting. We applied the technique to a range of lithologies at five sites in southeast Queensland in the Brisbane area, each an exposure of phyllite, granite, mudstone, argillite or volcanic tuff. The aims were: (1) quantifying the response of different rock masses to the AEM technique; and (2) assessing the applicability of the AEM as a rapid in situ measure of rock hardness by comparing results with Schmidt hammer 'R' values from the same exposures. Results showed that the AEM is useful in discriminating rock hardness across rocks with different lithological properties. Second, an

  19. Mineralogy and thermal properties of kaolin from the San José (Oruro, Bolivia)

    Science.gov (United States)

    Alfonso, Pura; Garcia-Valles, Maite; Martínez, Salvador; Amando Penedo, Lucio; Elvys Trujillo, Juan

    2016-04-01

    The San José mine, Oruro, Bolivia is known for provided a broad diversity of minerals. The San José Sn deposit is a Sn-Ag deposit composed of veins hosted in a complex of Miocene domes from monzonitic to dioritic composition within rhyolitic volcanic rocks hosted in Tertiary sedimentary rocks. Advanced argillitic alteration. is widespread in the surroundings of the deposit. Kaolinitization reach industrial importance and the kaolinitized rock is exploited, however it was not already been characterised. In this study we present a preliminary mineralogical and thermal characterization to determine the industrial applications of these kaolinitic materials. A sampling of the kaolinitized rocks in outcrops from the mining area was undertaken. The chemical composition of major and trace elements was determined by X-ray fluorescence (XRF). Mineralogy was obtained by powder diffraction X-ray (XRD) and infrared spectroscopy (FTIR). Quantitative determination of phases was obtained by the Rietveld refinement method using the Fullprof software. Thermal properties were determined by differential thermal analysis-thermo gravimetry (DTA -TG) and dilatometry. Mineral phases determined are mainly quartz (54-55 wt. %), kaolinite (7-8 wt. %), K-feldspar (8-19 wt. %), muscovite (16-17 wt. %), plagioclase up to 3 wt. %, alunite up to 8 wt% and gypsum up to 4 wt%. DTA -TG show a first endothermic event related to the dehydration of gypsum, with a loss weight of 0.4 wt%. An endothermic peak corresponding to the loss of the OH- groups of kaolinite occurs about 520 °C and an exothermic, at 980 °C, due to the crystallization of the mullite phase. The endothermic peak is attributed to the transformation of kaolinite in metakaolinite: Al2Si2O5 (OH)4  Al2Si2O7 + 2H2O and the dehydroxilation of alunite; the loss weight associated with this event is 2.9-3.2 wt%. The exothermic peak is caused by the formation of mullite: 3Al2Si2O7  Al6Si2O13 + 4SiO2. Another loss weight, of 3wt%, is

  20. Wireless Monitoring Study in the Meuse / Haute-Marne Underground Research Laboratory, France - 12046

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kei; Eto, Jiro; Tanabe, Hiromi [Radioactive Waste Management Funding and Research Center - RWMC (Japan); Mayer, Stefan; Bertrand, Johan [National Radioactive Waste Management Agency - ANDRA (France); Takamura, Hisashi; Suyama, Yasuhiro [Kajima Corporation (Japan)

    2012-07-01

    Two types of wireless transmission systems using ultra low frequency (8.5 kHz) were developed and used in the Callovo-Oxfordian argillites layer in the Meuse / Haute-Marne Underground Research Laboratory (CMHM URL) in France. Short-range and mid-range transmission antennas received data transmitted from 25 m to 50 m away. From the results of two series of tests, it is clear that transmission is practical when the received voltage is larger than the received noise. However, it is also clear that wireless transmission in the CMHM URL gallery is affected by the electromagnetic noise level and steel components, and the maximum transmission distance depends on the S/N ratio. The mid-range transmission antenna achieved a transmission distance of 240 m in the surface test, where the electromagnetic noise level was small and there was no environmental attenuation. The short-range transmission antenna achieved a transmission distance of 25 m in the surface test and in the CMHM URL gallery. As the clay layer of the CMHM URL had little effect on the attenuation of the electromagnetic field, transmission over 200 m might be possible in the CMHM URL when the electromagnetic noise level is small enough and there are no significant factors enhancing attenuation. But in reality, the possible transmission distance was around 50 m. In order to show the transmitter's ability, it is preferable to keep some distance between steel components and the transmitter. The most effective way to use this transmitter is to put it in a borehole drilled from a gallery to outside of a gallery around 10 m length. In this way, it might be possible to avoid almost of all the influence of steel components. For the position of receiver, the recommendation is the same as for the transmitter. That is, place the receiver where the incoming signal from the transmitter suffers little attenuation from steel components. Therefore, the option of implementing a receiving antenna in a borehole is required

  1. Clay matrix voltammetry

    International Nuclear Information System (INIS)

    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 (FeS2), 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

  2. Caracterização dos argilominerais usados em matéria-prima cerâmica, da formação Rio do Rasto, Bacia do Paraná, no município de Turvo, SC Characterization of clay minerals used in the ceramic industry, from Rio do Rasto formation, Paraná basin, exploitation in Turvo, SC, Brazil

    Directory of Open Access Journals (Sweden)

    J. A. Costa

    2010-12-01

    Full Text Available No sudeste de Santa Catarina existem inúmeras minas de exploração de argilas destinadas à indústria cerâmica da região. Para o conhecimento desta matéria prima foi realizada a caracterização em detalhe de uma frente de lavra em atividade. A exploração é realizada em terrenos sedimentares da Formação Rio do Rasto (Permiano Superior na Bacia do Paraná que afloram como morros testemunho. Foram coletadas quatorze amostras representativas dos níveis desta mina composta de argilitos com intercalação de siltitos de pequena espessura. As amostras foram analisadas por difratometria de raios X pelo método do pó na rocha total e na fração In the southeastern part of Santa Catarina state, Brazil, many mines of clays used as raw material for the ceramic industry are found. A detail study of this material was developed in a mine in activity. The exploitation of clays is held in sedimentary rocks of Rio do Rasto Formation (Upper Permian in the Paraná Basin. The outcrops are in hills testimonies. Fourteen samples were collected and represent the levels of this mine which consisted of argillites with intercalation of slim siltite layer. These samples were analyzed by X-ray diffraction using the powder method and in the fraction < 4 µm. The chemical composition was determined by X-ray fluorescence spectrometer. Petrographic observations in thin section were also performed. Scanning electron microscope images was obtained in samples fragments by secondary electron method. Electron microprobe microanalysis was performed in one thin section. The results showed large vertical variation in the mineralogy and it has been identified three different levels. Up to 2.00 m there is a predominance of smectite. Between 5.50 m 2.00 m the smectite is the main clay mineral, but with significant amounts of illite/mica and above 5.50 m occurs large increase in K-feldspar and detrital mica. Studies in detail by X-ray diffraction (determination of the b

  3. Molecular simulation of the role of interlayer water on the mechanical properties of montmorillonite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Full text of publication follows: Montmorillonite - a swelling clay - is the main component of the clay fraction of the Callovo-Oxfordian argillite, which is considered as a possible host rock for radioactive waste disposal, and of the sealing bentonite plugs of storage tunnels. Montmorillonite layers have a great ability to adsorb water, resulting in the swelling of the clay. Montmorillonite consists of water molecules and sodium or calcium cations between negatively charged layers. Both the water content of the interlayer space and the nature of the charge-balancing cations are expected to have an effect on the mechanical properties of the clay layer. Computer simulations allow to reproduce the experimental swelling isotherms of the layers and to gain a deeper understanding of the physical mechanisms of the swelling process. They show how water is organized in discrete layers and how this process depends on the type of inter-layer cation. However, the effect of the swelling on the mechanical properties of the nano-scale have not been fully investigated. The objective of this work is to compute the elastic properties of a Na+- Montmorillonite and a Ca2+-Montmorillonite versus relative humidity at 300 K. The results of this work is the first step to build a macroscopic state equation of unsaturated clay-based materials. We use a simulation cell containing two Montmorillonite layers and sodium or calcium counterions. The partial charges of the atoms and the interatomic interaction parameters are given by the CLAYFF force field. Grand Canonical Monte-Carlo simulations are used to compute the adsorption/desorption isotherm. Each equilibrium configuration is then strained in all directions of space. Then, we perform Molecular Dynamics and compute the stress tensor and all the components of the elasticity tensor. We present the evolution of the elastic properties of the clay layers with the relative humidity. In

  4. Mineralogical and sulfur isotopic characterization of the sulfur-bearing mineralization from the active degassing area of Campi Flegrei caldera (southern Italy)

    Science.gov (United States)

    Mormone, Angela; Piochi, Monica; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-04-01

    The Campi Flegrei caldera is a site of persistent hydrothermal circulation and gaseous emissions inside the Pozzuoli town and nearby the city of Napoli (Italy). The solfataric phenomena are associated with episodes of low-magnitude seismicity and vertical ground displacement since Roman times, evolving to the Monte Nuovo eruption in the 1538 AD. Pronounced geochemical anomalies, uplift rates up to 1 m/y and up to ten thousands microearthquakes per year also characterized the four most recent decades of unrest. The degassing phenomena are concentrated within the Solfatara crater, although, since 2006, the hydrothermal activity strongly increased in the Pisciarelli district, i.e. on the north-east slope of the tuff. We investigated sulfur-bearing mineral precipitates sampled from the active fumaroles both within the Solfatara and along the Pisciarelli slope. Mineral assemblage, texture and chemistry were determined for the efflorescence precipitated nearby the fumaroles and along the mud pool by x-ray diffraction, back-scattered electron microscope and electron diffuse microanalysis. δ34S compositions were also determined on separated sulfur-minerals. The new data have been compared with scattered literature data, including few existing for the previous '70 and '80 unrest episodes. Native sulfur and alunite are the main mineral phases that associate with alunogene, and, locally, pickeringite and potassium alum. Sporadically mereiterite, amarillite, and pyrite have been found as neogenesis mineralization along the outcropping rocks. The mud pool is rich in gypsum, potassium alum and pyrite. δ34S values range from -5.48 to 0.0‰, being slightly lower than previous data. The obtained results suggest that the Pisciarelli area is characterized by magmatic-hydrothermal, magmatic-steam and steam-heated environments, developed on a argillitic hydrothermal facies that thickens in correspondence of the degassing area. These environments develop and continuously evolve in

  5. Characterisation of iodide retention on Callovo-Oxfordian argilites by batch, column and through-diffusion experiments

    International Nuclear Information System (INIS)

    Full text of publication follows: Iodine-129 is commonly among the largest contributors to the calculated health risk associated with long-term nuclear underground waste disposal. Therefore, its behaviour in Callovo-Oxfordian argilites, the argillaceous host rock of the ANDRA Meuse/Haute-Marne underground laboratory, must be fully characterized. A weak and reversible sorption of iodide on surface clay and oxide minerals is often opposed to an irreversible retention on organic matter, more intense but kinetically slower. In the present study, several experimental methods (batch experiments, Stop and Flow columns and through-diffusion cells) have been implemented to study and quantify iodide ion retention, using 125I- as radiotracer. Several argillite cores were studied, coming from different back-holes (EST205 and EST312/322). All the experiments were performed with a synthetic solution, as close as possible of the natural pore water. Thiosulfates were systematically added to the synthetic solution in order to ensure the predominance of iodide. Sorption/desorption on batch tubes and column experiments have firstly been conducted to investigate the nature of iodine retention on argilites. Irreversible sorption of iodide was demonstrated with both methods, when long contact duration was provided. On the contrary, no reversible sorption of iodide was detected. Nevertheless, rock oxidation, conversion to iodates, may be encountered with these long-time experiments. Hence, through-diffusion cells were carried out in order to get closer to in situ physico-chemical conditions. Moreover, these experiments allow to work directly on centimetric rock samples (without crushing). During preparation and equilibration, careful attention was brought to maintain a permanent anoxic atmosphere (operations in an anhydrous and anoxic glovebox). All sampling were also made under a CO2/N2 flux. Influence of total iodine concentration (2.10-7 to 10-3 mol.L-1) was studied, comparing 125I

  6. Non intrusive quantification of the evolution of the water content in clayey samples using magnetic resonance imaging (MRI)

    International Nuclear Information System (INIS)

    calibration curve and to observe the progressive homogenization of the water content inside the cell. Finally, samples were submitted to air-dry or to progressive imbibition in order to test the evolution of spatial distribution of water in the sample. The following of the study consists in refining the method at low water content, then applying the method to Bure argillite, before to investigating the impact of a thermal stress on the distribution of the water inside the sample. (authors)

  7. Expectations, open questions to be addressed in the workshop within the context of a deep geological repository in clay formations

    International Nuclear Information System (INIS)

    Precise knowledge of the clay properties in the various domains concerned by the construction feasibility, the exploitation phase of repository facilities, as well as the long term evolution of the waste and of its environment is of crucial importance in assessing the performance and the safety of the various radioactive waste disposal concepts. The knowledge to be acquired on clays as such goes well beyond solely the field of disposal of radioactive waste. For both, clay formations or bentonites in engineered barriers, the characterization in a continuous way from the nanometer to the micrometer, of their internal structure and the study of the associated physico-chemical phenomena is a fundamental issue. It aims for explaining: The 'Initial state' of the clays, in particular for the clay formations: the nature of the mechanical, hydraulic and geochemical processes, in a broad sense, and the way these processes were involved during the geological history of these formations, The fundamental processes involved by physico-chemical or hydraulic stresses, related to the evolution of the repository at the macroscopic scale. The choice of the characterization scale and relevant modeling is of first importance in the approaches leading to the establishment of the models of representation. Various research works pointed to experimental difficulties in quantifying the microstructure of the clay rocks at scales smaller than a micrometer, because of technical/instrumental limitations. This lack of knowledge at small scales does not allow to fully connect all the Thermal-hydrological-mechanical-chemical (THMC) mechanisms and to integrate them into an up-scaling approach. There already exist conceptual models and experimental approaches to describe the microstructure of argillaceous formations in terms of porosity and texture. Examples on the undisturbed Callovo-Oxfordian (COx) argillite are given in this paper. Questions and objectives to be addressed during the

  8. The preliminary data on the Aeronian (Silurian) machaerids from Lithuania (Baltic Basin)

    Science.gov (United States)

    Radzevičius, S.; Ekleris, A.

    2012-04-01

    Machaerids are stem-Lophotrochozoans, closely related to the Annelids, and known from the Early Ordovician to Middle Permian. Machaerids is a group of worm-like benthic marine, bilaterally symmetrical, armoured invertebrate. Their body is covered by an external scleritome. The scleritome is imbricated of longitudinally arranged series of plates or sclerites. Completely articulated specimens of machaeridians are very rare, yet the systematic position of machaerids is controversial. Machaeridians had been assigned to different groups, such as barnacles, mollusks, echinoderms and annelids. The latter is prevailing, however their exact place within the annelids still remains unresolved. New findings of disarticulated Silurian machaerids have been recorded in western Lithuania, Geniai-1 core. This well has been drilled with exploration purposes regarding the Cambrian oil reservoir; therefore the biggest part of the Silurian core has not been collected. The exceptions are some parts of the Llandovery and Ludlow, which have partially recovered well core, but the identification of the precise stratigraphical position is complicated. Disarticulated sclerites of machaeridians have been found at the 1756.4 m depth, in the argillite, together with some graptolites and brachiopods. Several rhabdosome fragments of Normalograptus scalaris (Hisinger) were found together with the machaenid sclerites as well. N. scalaris has wide biostratigraphical distribution from the Rhudanian to the lower part of Telychian, which comprises the convolutus - triangulates graptolite biozones, corresponding to the 1756.8 - 1756 m depth. Convolutus - triangulates biozones represent Aeronian, and the machaeridian sclerites come from this interval, together with the Jonsea grayi (Davidson) brachiopod shells, which are very common and correspond to the BA 5-6 benthic assemblage, as well as do the graptolites found together. In previous studies, two orders of machaerids have been recognized: the

  9. Long-term lining performance - Civil engineering problem of potential retrieval of buried spent nuclear fuel

    International Nuclear Information System (INIS)

    The current solution for the spent fuel, high-level and long-lived radioactive waste is to store them at surface facilities from which they will be subsequently moved to a deep repository. No such repositories are in operation currently but several such facilities are close to the construction phase. A deep repository can be situated in several types of geological conditions including clay formations, salt sediments, argillites and tuffitic and granitic rocks. The character of the host rock is the key factor determining the design and specific requirements of individual components of such a facility. The future potential retrieval of canisters containing nuclear waste from the repository is a further influential factor. The reason for retrieval of containers lies in the development of fast reactors and increased interest for spent fuel reprocessing. Naturally, the decision as to whether retrievability is technically feasible must be made before finalising the design and construction process of the repository. If the decision is made to retrieve, a design which will include all the relevant safety aspects for the potential retrieval of canisters must be determined. The lay-out of the repository, the materials to be used and the design of the various structures of the facility (e.g. access tunnels, disposal shafts, buffer and backfill) are not the only issues to be addressed. The long-term stability of the system as a whole, i.e. of all the components, is crucial. Depending on the disposal concept chosen, the thermal load generated by the waste in the disposal container, saturation by water from the surrounding environment and the loading of the host rock massif will constitute the main processes which will affect the behaviour, safety and future functioning of the repository from the civil engineering point of view. The long-term stability of the lining of disposal galleries is a basic precondition for the safe removal of spent nuclear waste from deep underground

  10. Thermo-osmosis coupled-flow characterization in clay-rocks: experiments and modeling

    Science.gov (United States)

    Tremosa, J.; Goncalves, J.; Matray, J.; Violette, S.

    2009-12-01

    Water flow in clay-rocks is not only driven by a hydraulic gradient but also by chemical, thermal or electrical gradients. It implies a re-evaluation of the Darcy law by considering all gradients occurring in the clay-rock and their associated coupling coefficients (e.g. the osmotic efficiency to link a chemical gradient to a water flow). The occurrence of such processes in clay-rocks is due to the low hydraulic conductivity of this media and because of electrical charges at the clay minerals surface. Here, we focused on the thermo-osmosis process, a water flow under a temperature gradient, which is poorly characterized in spite of its implications in nuclear waste storage in clay-rocks. A set of thermo-osmotic experiments was performed in an equipped borehole installed in a Toarcian compacted clay at the IRSN’s Underground Research Laboratory in the south of France. The water flow induced by a temperature gradient (from the hotter towards the colder zone) was reproduced by the help of a numerical model, including coupled-flow processes, mass conservation laws and hydro-thermo-mechanical changes (see Figure). A range of thermo-osmotic permeability (kT), between 6.10-12 and 2.10-10 m2.K-1.s-2, was obtained during the experiments depending on the temperature gradient and uncertainties on the model parameters. Values obtained for the Tournemire’s argillite are in the high range of thermo-osmotic permeabilities for argillaceous materials and suggest an effect of pore size on the thermo-osmotic permeability of a clay-rock (kT being higher with little pore size). Another dependence of thermo-osmotic permeability with temperature is observed, with kT decreasing when the temperature increases. These experiments and modeling indicate thermo-osmosis will have an influence on water flow in presence of a temperature gradient and this process is to consider in water flow studies in clay-rocks. Reference: Tremosa et al. Estimating thermo-osmotic coefficients in clay

  11. Rheology, strain localization and stress history in the limestones of Bure (Meuse, France)

    International Nuclear Information System (INIS)

    In order to demonstrate the feasibility of a radioactive waste repository (HLW) in clay-stone formation, the french national radioactive waste management agency (Andra) started in 2000 to build an underground research laboratory (URL) at Bure in the south of the Meuse district. The target horizon for the laboratory is a 135 m thick layer of argillaceous rock (Callovo-Oxfordian clay-stone) that lies between about 420 and 555 meters below the surface at the URL site. The argillite layer (COX) is surrounded by limestones from the Dogger and the Oxfordian ages (respectively 164,7 to 175,6 Ma and 161,2 to 164,7 Ma). Numerous stylolites were found in these limestones. The aim of this work is to study the rheology of these stylolites-rich horizons and the stylolites as stress gauges in the Dogger and Oxfordian formations. In this work, a wide range of samples with and without stylolites were sampled in the Dogger and Oxfordian formations. Petrophysical measurements and microstructural studies showed that all these limestones have a microporous structure. We showed that the stylolites induced significant variations in some physical properties and in the rock strength. Based on an analytical model, presented here in details, linking a characteristic length associated to the stylolites morphology and the stress associated to the development of that stylolites, a method for the morphology analysis of stylolites is developed, using a Fourier power spectrum technique, by taking into account all the difficulties linked to the use of cores from deep boreholes. We apply this method on stylolites at various depths, starting from the Oxfordian formation at a depth of 158 meters to the Dogger formation at a depth of 800 meters. No stylolites are found in the intermediate Callovo-Oxfordian clay-stone formation. We analyze 1D profiles taken on the outer part of the cores. In agreement with theoretical predictions, we always observe two regimes for small and large scales separated by a

  12. Secondary hydrothermal mineral system in the Campi Flegrei caldera, Italy

    Science.gov (United States)

    Mormone, A.; Piochi, M.; Di Vito, M. A.; Troise, C.; De Natale, G.

    2012-04-01

    Mineral systems generally develop around the deep root of the volcanoes down to the degassing magma chamber due the selective enrichment process of elements within the host-rock. The mineralization process depends on i) volcanic structure, ii) magma and fluid chemistry, iii) host-rock type and texture, iv) temperature and pressure conditions, and v) action timing that affect the transport and precipitation conditions of elements in the solution. Firstly, it generates a hydrothermal system that in a later phase may generate considerable metallogenic mineralization, in terms of both spatial extension and specie abundance. The study of secondary assemblages through depth and, possibly, through time, together with the definition of the general geological, structural, mineralogical and petrological context is the background to understand the genesis of mineral-to-metallogenic systems. We report our study on the Campi Flegrei volcano of potassic Southern Italy belt. It is a sub-circular caldera characterized by an active high-temperature and fluid-rich geothermal system affected by seismicity and ground deformation in the recent decades. The circulating fluids originate at deeper level within a degassing magma body and give rise at the surface up to 1500 tonnes/day of CO2 emissions. Their composition is intermediate between meteoric water and brines. Saline-rich fluids have been detected at ~3000 in downhole. The hydrothermal alteration varies from argillitic to phillitic, nearby the caldera boundary, to propilitic to thermo-metamorphic facies towards its centre. The Campi Flegrei caldera was defined as analogue of mineralized system such as White Island (New Zealand) that is an example of an active magmatic and embryonic copper porphyry system. In order to enhance the knowledge of such a type of embryonic-like metallogenic system, we have carried out macroscopic and microscopic investigations, SEM-EDS and electron microprobe analyses on selected samples from deep wells

  13. 2005 dossier. ANDRA's researches on the geological disposal of high-level and long-lived radioactive wastes. Results and perspectives

    International Nuclear Information System (INIS)

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in deep geologic formations (argilites and granites). Content: 1 - Research on deep disposal of radioactive waste: general interest task: Legislative framework, ANDRA scientific objectives, Inspections and assessments; 2 - Designing a safe and reversible disposal system: Repository safety, Reversibility: an essential requirement; 3 - Clay Research on a repository in a clay formation, A long research programme, Dossier 2005 Argile; 4 - Meuse/Haute-Marne site clay: Expected properties of the rock formation, Choice of argillite, Meuse/Haute-Marne site, Conclusions from 10 years of research at the Meuse/Haute-Marne site; 5 - Repository installations: Safe and reversible architecture, Disposal of B waste, Disposal of C waste, Possible disposal of spent fuel (CU); 6 - The disposal facility in operation: From waste packages reception to their disposal in cells, Stages of the progressive closure of engineered structures; 7 - Reversible management: Freedom of choice for future generations, Various closure stages; 8 - Long-term evolution of the repository: Apprehending the repository complexity Main evolutions expected, Slow and limited release of radioactive substances; 9 - Repository safety and impact on man: Several evolution scenarios, Normal evolution, Altered evolution; 10 - Granite Research on a repository in a granite formation: A global approach, Scientific co-operations, Dossier 2005 Granite; 11 - Characteristics of French granite formations: What properties are required for a repository?, Different types of granite formations; 12 - Repository installations: Repository design adapted to granite fractures, Clay seals to prevent water flows, Waste disposal packages ensuring long-term leak-tightness, Physical and chemical environment favourable for waste packages, Architecture

  14. 2005 dossier. ANDRA's researches on the geological disposal of high-level and long-lived radioactive wastes. Results and perspectives; Dossier 2005. Les recherches de l'Andra sur le stockage geologique des dechets radioactifs a haute activite et a vie longue. Resultats et perspectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-06-15

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in deep geologic formations (argilites and granites). Content: 1 - Research on deep disposal of radioactive waste: general interest task: Legislative framework, ANDRA scientific objectives, Inspections and assessments; 2 - Designing a safe and reversible disposal system: Repository safety, Reversibility: an essential requirement; 3 - Clay Research on a repository in a clay formation, A long research programme, Dossier 2005 Argile; 4 - Meuse/Haute-Marne site clay: Expected properties of the rock formation, Choice of argillite, Meuse/Haute-Marne site, Conclusions from 10 years of research at the Meuse/Haute-Marne site; 5 - Repository installations: Safe and reversible architecture, Disposal of B waste, Disposal of C waste, Possible disposal of spent fuel (CU); 6 - The disposal facility in operation: From waste packages reception to their disposal in cells, Stages of the progressive closure of engineered structures; 7 - Reversible management: Freedom of choice for future generations, Various closure stages; 8 - Long-term evolution of the repository: Apprehending the repository complexity Main evolutions expected, Slow and limited release of radioactive substances; 9 - Repository safety and impact on man: Several evolution scenarios, Normal evolution, Altered evolution; 10 - Granite Research on a repository in a granite formation: A global approach, Scientific co-operations, Dossier 2005 Granite; 11 - Characteristics of French granite formations: What properties are required for a repository?, Different types of granite formations; 12 - Repository installations: Repository design adapted to granite fractures, Clay seals to prevent water flows, Waste disposal packages ensuring long-term leak-tightness, Physical and chemical environment favourable for waste packages, Architecture

  15. Spatial Heterogeneity of Stream Water Chemistry in the Elder Creek Catchment at the Eel River Critical Zone Observatory.

    Science.gov (United States)

    Thurnhoffer, B. M.; Lovill, S. M.; Nghiem, A.; Kim, H.; Bishop, J. K. B.

    2014-12-01

    How does stream chemistry vary with respect to discharge, flow distance, elevation, hill slope orientation, lithology, and vegetation on catchment scale? Is it possible to discern fast flowing seasonally recharged subsurface waters from long residence time waters contributing to base flow? To answer these questions, water samples were collected at ~80 locations distributed over the channel network of the (17 km2) Elder Creek catchment during surveys in May and August/September 2014. The site, located at the Angelo Coast Range Reserve near the headwaters of the South Fork of the Eel River in northern California, experiences a Mediterranean climate with warm dry summers and cold wet winters; this year (2014), our area has received less than 50% of expected precipitation and is experiencing an extreme drought. Our survey times correspond to the beginning of the dry season and late dry season, respectively. The subsurface lithology of the region almost uniform, being largely composed of argillite mudstone with intermittent areas underlain with sandstone. It is forested with Douglas fir, live and tan oaks, madrone and California bay laurel, which vary in abundance with hill-slope orientation. Due to drought, the Elder Catchment has recently experienced the effects of the nearby Lodge Lightening Complex Fire (first detection July 31 2014) and its effects may be differentiated through the continuous 1 - 3 day frequency sampling of Elder Creek water using the ISCO Gravity Filtration System (GFS; Kim et al. 2012, EST). All water samples are analyzed for dissolved major, minor, and trace solutes by Inductively Couple Plasma Mass Spectrometry and this report focuses on major solutes such as Na, K, Ca, Mg and Si; redox sensitive metals Fe and Mn; and Ba and Sr. Preliminary analysis of May 2014 data shows interesting patterns between tributaries, particularly differences between streams on north vs. south facing slopes. Concentrations of Ca, Mg, and Na decrease down slope in

  16. NEW PALEOMAGNETIC DATA ON THE SILURIAN AND DEVONIAN SEDIMENTARY ROCKS FROM PODOLIA, SW UKRAINE, AND KINEMATICS OF THE EAST EUROPEAN PLATFORM IN THE MIDDLE PALEOZOIC

    Directory of Open Access Journals (Sweden)

    V. G. Bakhmutov

    2015-09-01

    Full Text Available Paleomagnetic data are the priority source of information for global paleotectonic reconstructions representing horizontal movements of the crustal blocks. Upon receipt of new paleomagnetic data, kinematic models of the East European platform in the Paleozoic are regularly revised and improved. The article presents results of the paleomagnetic study of sedimentary gray-colored and red beds of the Silurian and Lower Devonian sequences located in the Dniester river basin, Podolia region, SW Ukraine. The study covered 17 outcrops that are stratigraphically correlated with the Wenlock, Ludlow, Pridoli states of the Sillurian and the Lochkovian stage of the Devon. Over 400 samples of grey limestone, argillite, dolomite, red limestone and sandstone were analyzed, and two components of natural remnant magnetization (NRM were revealed. The first component with SSW declination and negative inclination is revealed in the majority of the samples during AF- and T-magnetic cleaning. Its pole positions, that are calculated separately for each series, are trending to the Permian segment of the apparent polar wander path (APWP published by Torsvik et al. [2012] for Baltica / Stable Europe. Considering its chemical origin, this NRM component is related to formation of authigenic minerals due to rock remagnetization. The second component is revealed only in some samples taken from the red beds (during thermal demagnetization in the range of unblocking temperatures from 590 to 690 °С and in few samples of grey limestone (in AF fields from 30 to 70 mT or in the range of unblocking temperatures from 300 to 460 °С. This component has SW declination and positive inclination, goes to the origin of coordinates of the diagrams, and has all the indicators of primary magnetization of sediments. Calculated positions of the poles (0 ºS and 329 ºE for grey limestone of the Tiverskaya series, 2.3 °S and 338.4 °E for red beds of the Dniestrovskaya series, etc. are well

  17. Air oxidation of samples from different clay formations of East Paris basin: quantitative and qualitative consequences on the dissolved organic matter

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. During the excavation and the building of an underground research laboratory in clay geological formations, exposure to air is one of the most important parameters affecting the composition of fossil organic matter. Indeed the net effect of air oxidation of the organic matter is enrichment in oxygen and carbon combined with a loss of hydrogen. Effluents formed are CO2 and water as well as the liberation of hydrocarbons. This process may have an impact on water chemistry of the clay, especially on the quantity and composition of Dissolved Organic Matter (DOM). The clays studied were the following and may be distinguished on the basis of their organic matter content: - The Callovo-Oxfordian argillite, collected in the Bure Underground Research Laboratory (Meuse, France), which contains a mixture of type II and III kerogen; - The Toarcian shales of East Paris Basin collected from drilling EST 204 (Meuse, France) contains type II kerogen; - The Kimmeridgian shales of East Paris Basin collected from drilling HTM 102 (Meuse, France) also contains type II kerogen. The powdered clay samples were oxidized in a ventilated oven at 100 C under air flow during 2, 256, 512 and 1088 hours for Callovo-Oxfordian samples and during 512 and 2048 hours for Toarcian and Kimmeridgian samples. The DOM of each sample was extracted by soxhlet using pure water. Different analyses were carried out: - Quantitative evolution of DOM with the oxidation process; - Evolution of several chemical parameters of DOM with oxidation using molecular analyses (PyGC-MS) molecular weight distribution (GPC-HPLC) as well as spectroscopic measurements (3D-Fluorescence). Increasing oxidation induces an increase of DOC values for all samples. Also, Changes in the chemical composition of the DOM are observed: decrease in the molecular weight range; enrichment in acidic functional groups (alkane-dioic acids, alkanoic acids, aromatics poly acids). Moreover the

  18. Long-term lining performance - Civil engineering problem of potential retrieval of buried spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Vasicek, Radek, E-mail: radek.vasicek@fsv.cvut.c [Czech Technical University in Prague, Faculty of Civil Engineering, Centre of Experimental Geotechnics, Thakurova 7, 16629 Prague 6 (Czech Republic); Svoboda, Jiri, E-mail: jiri.svoboda@seznam.c [Czech Technical University in Prague, Faculty of Civil Engineering, Centre of Experimental Geotechnics, Thakurova 7, 16629 Prague 6 (Czech Republic)

    2011-04-15

    The current solution for the spent fuel, high-level and long-lived radioactive waste is to store them at surface facilities from which they will be subsequently moved to a deep repository. No such repositories are in operation currently but several such facilities are close to the construction phase. A deep repository can be situated in several types of geological conditions including clay formations, salt sediments, argillites and tuffitic and granitic rocks. The character of the host rock is the key factor determining the design and specific requirements of individual components of such a facility. The future potential retrieval of canisters containing nuclear waste from the repository is a further influential factor. The reason for retrieval of containers lies in the development of fast reactors and increased interest for spent fuel reprocessing. Naturally, the decision as to whether retrievability is technically feasible must be made before finalising the design and construction process of the repository. If the decision is made to retrieve, a design which will include all the relevant safety aspects for the potential retrieval of canisters must be determined. The lay-out of the repository, the materials to be used and the design of the various structures of the facility (e.g. access tunnels, disposal shafts, buffer and backfill) are not the only issues to be addressed. The long-term stability of the system as a whole, i.e. of all the components, is crucial. Depending on the disposal concept chosen, the thermal load generated by the waste in the disposal container, saturation by water from the surrounding environment and the loading of the host rock massif will constitute the main processes which will affect the behaviour, safety and future functioning of the repository from the civil engineering point of view. The long-term stability of the lining of disposal galleries is a basic precondition for the safe removal of spent nuclear waste from deep underground

  19. Results from the geological surveys carried out in the Bure laboratory's drifts

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. After the government's authorization to build and operate an underground laboratory, Andra started the investigation works in November 99 on the Meuse/Haute-Marne URL site. The Meuse/Haute-Marne URL is located at the border of the Champagne-Ardenne and Lorraine regions, on the township of Bure in the Callovo-Oxfordian clay-rich rock. At this place, the layer is about 135 m-thick and lies at a depth of 417 m to 552 m. The construction of the underground installations started in August 2000 with the sinking of the main shaft and the first phase of diggings was completed on the 27 April 2006 when it linked up with the south drift of the laboratory. The laboratory consists in two vertical shafts crossing the 505-m thick sedimentary cover and two levels of experimental drifts dug in Callovo-Oxfordian formation. The first experimental drift dug at -445 m with a drill-and-blast method with steps of 2.4 m. The technical and experimental drifts at the main level (-490 m of depth) were dug with a hydraulic stone crusher. The aims of the geological surveys carried out during the drifts digging are to observe the lateral variation of the lithology, if there is one, to confirm the absence of fault and the geometry of the argillites formation. These works should also allow to characterize the natural or inducted fracturing (EDZ - Excavation Damaged Zone) induced by the digging by a sedimentary and structural follow-up. The EDZ characterization has been established from the geological survey of the drift face and sidewalls carried out from 1 to 5 meters in the drifts, and completed by the structural analysis of the cores of the boreholes drilled for the experimentations' equipments. After the safe keeping of the front, the geological team goes down to carry out the survey which consists in a lithologic and sedimentary mapping, a structural survey for the understanding of joints distribution and EDZ characterization, and

  20. Molecular modeling of the swelling properties and interlayer structure of Cs, Na, K-montmorillonite: effects of charge distribution in the clay layers

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Safe and sustainable management of nuclear waste poses major scientific challenges to make the environmental footprint of nuclear energy as small as possible for very long periods of time. As many other countries, France is considering the deep geological disposal (in the Callovo-Oxfordian (COx) argillite formations of the Paris basin) as a reliable way of storing high-level radioactive waste in order to provide adequate protection for humans and the environment. In addition to being proven geologically stable for million years, the natural and engineered clay barriers can benefit from many favorable properties, such as low permeability, high sorption capacity, etc. The mineralogical composition of the Callovo-Oxfordian argillite shows about 41% of clay minerals (23% of interstratified illite/smectite, 14% of illite-type minerals, 2% kaolinite and 2% chlorite). A non-negligible amount of organic matter is also present (∼1%), and it is known that the interaction of natural organic matter (NOM) with radionuclides and clays can affect the solubility and toxicity of trace elements in natural aqueous environments. Reliable prediction of the behaviour of radionuclides and their transport and retention in clayey formations at nuclear waste repositories requires detailed molecular scale understanding of these complex multicomponent systems. Computational molecular modelling has already become an important tool in the study of thermodynamic, structural and transport properties of hydrated clays. As the first step in our study of the effects of organic molecules on the adsorption and transport of radionuclides in hydrated clay systems we have investigated the effects of the ordering in charge distributions on the swelling behavior of simulated clays. Montmorillonite was chosen as a model of smectite clay. Montmorillonite structure consists of aluminum-oxygen octahedral sheet sandwiched between two opposing silicon

  1. Petrography, Geochemistry and Proposed Genesis of Ordovician Oolitic Iron Formation Members of the Lashkarak Formation, Eastern Alborz

    Directory of Open Access Journals (Sweden)

    Mansoore Maghsoudloo Mahalli

    2016-07-01

    Full Text Available Introduction Oolitic iron formations are sedimentary rocks with >5 vol.% oolites and >15 wt.% iron, corresponding to 21.4 wt.% Fe2O3 (Young, 1989; Petranek and Van Houten, 1997; Mucke and Farshad, 2005. In Iran, new iron oolite-bearing members have been identified in the Lashkarak Formation (lower-middle Ordovician in the Abarsej, Dehmola and Simehkuh sections, eastern Alborz (Ghobadi Pour et al., 2011. At present, the mineralogy and geochemistry of these members are not known. Consequently, research reported here was conducted to reveal the mineralogical and geochemical characteristics of Ordovician oolitic iron formationmembers and to discuss their genesis and economic importance. Materials and Analyses Field geology and sampling was carried out to collect 25 samples from the ooliticiron formation members in the Abarsej, Dehmola and Simehkuh section in eastern Alborz. Samples were prepared for polished-thin sections (n=10, XRD analysis (n=15. Whole-rock chemical analysis (n=15 by XRF for major elements and by ICP-ES for trace elements was performed by laboratories at the SarCheshmeh copper mine complex, Kerman, Iran. One sample was analyzed by SEM at the Wales Museum, UK. Results Microscopic studies show that the oolitic iron formation members are hosted by carbonate argillite rocks. They are mainly composed of oolites rather than pisoliths (small bodies somewhat larger and more irregular than oolites, whereas oolites have mainly ellipsoidal forms and locally spherical shapes. Most (6 oolites show banding with a central core. Simple oolites without a core are scarce. Mineralogically, oolites are mainly chamositic and hematitic in composition; goethite, pyrite and glauconite occur in traces and siderite is absent. Quartz, calcite and zircon are accessory minerals which are present in the groundmass. Geochemically, TFeO % of the oolitic iron formation horizons ranges from 8 to 48 % with an average of 21%. The CaO content ranges from 2 to 37% and

  2. Laboratory investigation of the mechanical behaviour of transversely isotropic Tournemire shale

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Argillaceous formations are characterized by the presence of bedding planes, resulting in anisotropy of their strength and deformation properties. In this investigation, 60 samples of shale were obtained from boreholes drilled at different angles in the walls and invert of an existing gallery at the Tournemire URL, France. In order to derive the parameters for the yield criteria for transversely isotropic shales, a laboratory test program is developed to investigate their mechanical properties. This testing program includes the measurement of basic properties of the shale, and uniaxial tests, triaxial tests, cyclic tests, and Brazilian tests. Acoustic Emission data were also measured. The laboratory tests were performed at different inclinations with respect to the bedding planes (0, 30, 45, and 60, 90 deg.). The results indicate that the Tournemire shale can be considered as a transversely isotropic material, with elastic properties and strength values that are strongly dependent on the relative orientation of the applied stress with respect to the bedding planes. The acoustic emission data indicate that the development and propagation of microcracks within the Tournemire shale only take place at high stress levels close to the peak strength. Sedimentary formations at the site are characterized by a 250 m thick sub-horizontal argillites and marls of Toarcian and Domerian, located between two aquifer limestone, and dolomite layers of Carixian and Aalenian. The massif is affected by faults and fractures, and the water circulation takes place along the lower and upper limestone aquifers. The argillite is characterized by the presence of sub-horizontal bedding planes and randomly distributed fractures. X-ray diffraction analysis showed that the shale consists of 55% of argillaceous minerals, 19% quartz, 15% calcite, and 11% of other materials such as dolomite, pyrite, siderite, and feldspars. Porosity varies between 6

  3. A new challenge: in-situ investigation of the elusive nanostructures in wet halite and clay using BIB/FIB-cryo-SEM methods

    Science.gov (United States)

    Desbois, G.; Urai, J. L.

    2009-04-01

    are able to stabilize the in-situ fluids in grain boundaries or pores, preserve the natural structures at nano scale, produce high quality polished cross-sections for high resolution SEM imaging and reconstruct accurately the grain boundary and the pore space networks in 3D by serial cross sectioning. Our first investigations on wet halite and wet clay materials produced unprecedented high quality images of fully preserved fluid-filled pore space as appear in nature. We have thus validated the use of the FIB/BIB-cryo-SEM technology for the in-situ investigations of the elusive structures in wet geomaterials paving the way towards a fuller understanding of how pore geometry can affect physical properties of rocks. [1] Desbois G. And Urai J.L. (submitted). In-situ morphology of meso-porosity in Boom clay (Mol site, Belgium) inferred by the innovative FIB-cryo-SEM method. E-earth. [2] Desbois G., Urai J.L., Burkhardt C., Drury M., Hayles M. and Humbel B. (2008). Cryogenic vitrification and 3D serial sectioning using high resolution cryo-FIB-SEM technology for brine-filled grain boundaries in halite: first results. Geofluids, 8: 60-72 [3] Esteban L., Géraud Y. And Bouchez J.L. (2006). Pore network geometry in low permeability argillites from magnetic fabric data and oriented mercury injections. Geophysical Research Letters, vol. 33, L18311, doi : 10.1029/2006GL026908. [4] Esteban L., Géraud Y. And Bouchez J.L. (2007). Pore network connectivity anisotropy in Jurassic argillite specimens from eastern Paris Basin (France). Physics and Chemistry of the Earth, 32(1) :161-169. [5] Hildenbrand A., Krooss B. M. and Urai J. L. (2005). Relationship between pore structure and fluid transport in argillaceous rocks. Solid Mechanics and Its Applications, IUTAM Symposium on Physicochemical and Electromechanical Interactions in Porous Media, 125 : 231-237, doi : 10.1007/1-4020-3865-8_26. [6] Hildenbrand A. and Urai J.L. (2003) Investigation of the morphology of pore space in mudstones

  4. Shale disposal of U.S. high-level radioactive waste.

    Energy Technology Data Exchange (ETDEWEB)

    Sassani, David Carl; Stone, Charles Michael; Hansen, Francis D.; Hardin, Ernest L.; Dewers, Thomas A.; Martinez, Mario J.; Rechard, Robert Paul; Sobolik, Steven Ronald; Freeze, Geoffrey A.; Cygan, Randall Timothy; Gaither, Katherine N.; Holland, John Francis; Brady, Patrick Vane

    2010-05-01

    This report evaluates the feasibility of high-level radioactive waste disposal in shale within the United States. The U.S. has many possible clay/shale/argillite basins with positive attributes for permanent disposal. Similar geologic formations have been extensively studied by international programs with largely positive results, over significant ranges of the most important material characteristics including permeability, rheology, and sorptive potential. This report is enabled by the advanced work of the international community to establish functional and operational requirements for disposal of a range of waste forms in shale media. We develop scoping performance analyses, based on the applicable features, events, and processes identified by international investigators, to support a generic conclusion regarding post-closure safety. Requisite assumptions for these analyses include waste characteristics, disposal concepts, and important properties of the geologic formation. We then apply lessons learned from Sandia experience on the Waste Isolation Pilot Project and the Yucca Mountain Project to develop a disposal strategy should a shale repository be considered as an alternative disposal pathway in the U.S. Disposal of high-level radioactive waste in suitable shale formations is attractive because the material is essentially impermeable and self-sealing, conditions are chemically reducing, and sorption tends to prevent radionuclide transport. Vertically and laterally extensive shale and clay formations exist in multiple locations in the contiguous 48 states. Thermal-hydrologic-mechanical calculations indicate that temperatures near emplaced waste packages can be maintained below boiling and will decay to within a few degrees of the ambient temperature within a few decades (or longer depending on the waste form). Construction effects, ventilation, and the thermal pulse will lead to clay dehydration and deformation, confined to an excavation disturbed zone within

  5. Molecular hydrogen: an energy source for bacterial activity in nuclear waste disposal

    International Nuclear Information System (INIS)

    sulfate reducing bacteria or methanogen bacteria. Iron reducing activity could develop near containers or in argillite. Several examples and results of kinetic of H2 consumption by microorganisms are here presented: - The development of bacteria using oxygen and H2 from radiolysis of water in basin containing irradiating waste. The development of denitrifying bacteria using nitrates and H2 in the environment of bituminized embedded waste. In presence of H2, bacteria will reduce the released nitrates from bituminized waste: the limiting factor of the kinetic is the amount of released nitrates. - The development of iron reducing bacteria using ferric iron and H2 from container corrosion products. Shewanella sp is able to oxidise 1.2 mmoles of H2/day by iron reduction. The consequences of the development of H2 oxidising bacteria are discussed in terms of physico-chemical modifications in geological disposal: biomass production, gas production and consumption, bio-corrosion

  6. Beyond the angle of repose: A review and synthesis of landslide processes in response to rapid uplift, Eel River, Northern California

    Science.gov (United States)

    Roering, Joshua J.; Mackey, Benjamin H.; Handwerger, Alexander L.; Booth, Adam M.; Schmidt, David A.; Bennett, Georgina L.; Cerovski-Darriau, Corina

    2015-05-01

    In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope angles approach a limiting value. For decades, the threshold slope model has been invoked to account for landslide-driven increases in sediment flux that limit topographic relief, but the manner by which slope failures organize themselves spatially and temporally in order for erosion to keep pace with rock uplift has not been well documented. Here, we review past work and present new findings from remote sensing, cosmogenic radionuclides, suspended sediment records, and airborne lidar data, to decipher patterns of landslide activity and geomorphic processes related to rapid uplift along the northward-migrating Mendocino Triple Junction in Northern California. From historical air photos and airborne lidar, we estimated the velocity and sediment flux associated with active, slow-moving landslides (or earthflows) in the mélange- and argillite-dominated Eel River watershed using the downslope displacement of surface markers such as trees and shrubs. Although active landslides that directly convey sediment into the channel network account for only 7% of the landscape surface, their sediment flux amounts to more than 50% of the suspended load recorded at downstream sediment gaging stations. These active slides tend to exhibit seasonal variations in velocity as satellite-based interferometry has demonstrated that rapid acceleration commences within 1 to 2 months of the onset of autumn rainfall events before slower deceleration ensues in the spring and summer months. Curiously, this seasonal velocity pattern does not appear to vary with landslide size, suggesting that complex hydrologic-mechanical feedbacks (rather than 1-D pore pressure diffusion) may govern slide dynamics. A new analysis of 14 yrs of discharge and sediment concentration data for the Eel River indicates

  7. 高放废物地质处置库中缓冲回填材料的收缩特征%Shrinkage characteristics of buffer-backfilling materials in high-level radioactive waste geological disposal

    Institute of Scientific and Technical Information of China (English)

    唐朝生; 施斌; 崔玉军

    2012-01-01

    The shrinkage characteristics of buffer-backfilling materials play an important role in the security and stability of the high-level radioactive waste geological disposal system. COx argillite is considered as a kind of potential buffer-backfilling materials in France. In this investigation, both the initially saturated compacted COx specimens and the paste-like COx specimens are prepared and subjected to different test methods to study their volumetric shrinkage behaviours. For the compacted specimens, it is found that the volumetric shrinkage deformation is significantly influenced by the initial dry density; the shrinkage limit, shrinkage efficiency and shrinkage strain decrease with the increasing dry density; in addition, it is observed that the shrinkage direction of specimens shows obvious anisotropism. For example, at low degree of compaction, the radial shrinkage strain is higher than axial shrinkage strain, and the shrinkage geometry factor is larger than 3; however, the contrary results are obtained at high degree of compaction. For the paste-like specimens, three shrinkage stages can be distinguished: normal shrinkage, residual shrinkage and zero shrinkage; most of the volume shrinkage deformation occurs before the air-entry point while the soil is still fully saturated. A group of four general shrinkage models are employed to fit the shrinkage curve of the paste-like specimens. The results show that the G & C model can get the highest performance for the present soil.%缓冲回填材料的收缩特征对高放废物处置库的安全性和稳定性有重要影响。以COx泥岩缓冲回填材料为研究对象,采用不同的试验方法分别研究了饱和的压实试样和糊状试样在干燥过程中的体积收缩变形特征。试验结果表明:压实试样的体积收缩变形特征受初始干密度的影响比较明显,缩限、收缩系数和收缩应变均随初始干密度的增加而减小;压实试样的体积收缩

  8. Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

    International Nuclear Information System (INIS)

    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, CaCl2 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 separated by

  9. Native sulfur, sulfates and sulfides from the active Campi Flegrei volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry

    Science.gov (United States)

    Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-10-01

    We investigated sulfur-bearing minerals from the Campi Flegrei caldera, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the caldera is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that

  10. Ten years of experience in technology development... What use for the Cigeo project?

    Energy Technology Data Exchange (ETDEWEB)

    Bosgiraud, Jean-Michel; Delort, Daniel [Andra, Chatenay-Malabry (France)

    2015-07-01

    Since 2003, Andra (the French public body in charge of radioactive waste management) has been working on the progressive technological development of waste storage containers, package handling mechanical prototypes, excavation techniques and support lining of underground openings at the Bure Underground Laboratory (URL) site, in order to evaluate the feasibility of constructing and operating a Deep Geological Repository (DGR aka Cigeo), in the Callovian-Oxfordian clayish formation (the ''Argillites''), likely to receive as of 2025-2030 the first of many intermediate and high-level long lived wastes, at a 500m depth. The Cigeo Project, which has now entered into an intense engineering development phase, must take into account all the data, knowledge and experience gathered over more than 10 years of technical research. The spectrum of activities concerned encompasses a wide array of subjects such as the return of experience gathered from the shaft sinking operations, the drift excavation operations (via means of rock hammer, road header and tunnel boring machine) and the subsequent lining support of the horizontal drifts (via metal arches, mesh, rock bolts, shotcrete, cast concrete and wedges). The story of coring, drilling and casing vertical, slanted or horizontal boreholes is also of interest. The implementation and evaluation of sealing technologies or hydraulic cut-offs must be integrated in the design. The construction and qualification in 3 campaigns of 9 families of concrete containers and 3 categories of carbon steel overpacks also come as input data. The design, construction and testing of 3 package emplacement systems, the implementation of 2 waste retrievability tests are accounted for in the studies ongoing. Finally the collation of environmental and geotechnical data on the excavated material (likely to be re- used for opening backfilling at time of repository closure) will help to minimize the acreage, volume and visual impact of

  11. Geology of the Blue Mountains region of Oregon, Idaho, and Washington; stratigraphy, physiography, and mineral resources of the Blue Mountains region

    Science.gov (United States)

    Vallier, T. L., (Edited By); Brooks, H.C.

    1994-01-01

    island-arc terrane. PART 2: Mesozoic rocks exposed along the Snake River in the northern Wallowa terrane represent a volcanic island and its associated sedimentary basins within the Blue Mountains island arc of Washington, Oregon, and Idaho. In the northern part of the Wallowa terrane, rock units include the Wild Sheep Creek, Doyle Creek, and Coon Hollow Formations, the (informal) Imnaha intrusion, and the (informal) Dry Creek stock. The volcanic rocks of the Ladinian to Karnian Wild Sheep Creek Formation show two stages of evolution-an early dacitic phase Gower volcanic faciesY and a late mafic phase (upper volcanic facies). The two volcanic facies are separated by eruption-generated turbidites of siliceous argillites and arkosic arenites (argillitesandstone facies). The two magmatic phases of the Wild Sheep Creek Formation may be recorded by the compositional zoning from older quartz diorite and diorite to younger gabbro in the Imnaha intrusion. Although the Late Triassic Imnaha intrusion is in fault contact with the Wild Sheep Creek Formation, it may be a subduction-related pluton and was the likely magma source for the Wild Sheep Creek Formation. Interbedded with the upper volcanic facies are eruption-generated turbidite and debris flow deposits (sandstone-breccia facies) and thick carbonate units (limestone facies). The limestone facies consists of two marker units, which may represent carbonate platform environments. Clast imbrication, fossil orientation, and cross-stratification in the Wild Sheep Creek Formation indicate a shoaling to subaerial volcanic island to the south and southeast; sediment was transported to the north and northwest. The Karnian Doyle Creek Formation consists largely of epiclastic conglomerate, sandstone, and shale that were deposited in welloxygenated basins. Vitric tuffs interbedded with these sediments suggest shallow or subaerial pyroclastic eruptions. Quartz diorite clasts in this formation may indicate uplift

  12. Weathering and genesis of Soils from Ellsworth Mountains, East Antarctica

    Science.gov (United States)

    Karoline Delpupo Souza, Katia; Schaefer, Carlos Ernesto; Michel, Roberto; Monari, Julia; Machado, Vania

    2015-04-01

    Knowledge on Antarctic soils from the Ellsworth Mountains (EM) are patchy comparatively with Dry Valleys soils from the Transantartic Mountains, and could help understand the genesis of cryogenic soils under extreme dry, cold desert conditions. The EM are a slightly arcuate 350-km-long north-northwest-trending mountain chain is bordered on the west by the polar plateau of West Antarctica and on the east by Ronne Ice Shelf. The range is as much as 90 km wide and constitutes one of the largest areas of exposed bedrock in West Antarctica. The stratigraphic succession in the EM includes strata from Cambriam to Permian in age. The objective of this study is to analyze the properties of soils from EM in order to identify the main factors and processes involved in soil formation under cold desert conditions in Antarctica. The sampling design aimed to represent the different geological substrates (marble-clast conglomerate, graywacke, argillite, conglomerate, black shale, marble and quartzite) as well as altitudinal levels and landforms within the same substrate. We characterized soils from EM regarding their morphological, physics and chemical properties. Soil samples were air dried and passed through 2 mm sieves. After removal of water soluble salts, the samples were submitted to chemical and physical analyses such as: pH in water, potential acidity (H + Al), exchangeable bases, total organic carbon, electric conductivity, soil texture and color. The soils classify, for the most part, in weathering stages 1 to 2. Only in the upper parts of ridges were there traces of soils at weathering stage 3. This indicates that much of the present icefree topography has been overridden by ice within the last few hundred thousand years. Cryoturbation is a widespread phenomenon in this area resulting in intense cryoclastic weathering and patterned ground, forming sorted circles, stripes and gelifluxion lobes. The soil show low horizontation, discrete patches of salt on the surface, and

  13. IHG: an Integrated Hydrological-Geotechnical model for large landslides' susceptibility assessments

    Science.gov (United States)

    Passalacqua, R.; Bovolenta, R.

    2012-04-01

    A large area (~ 5 km2) in the north-east sector of the Genoa-Province (Liguria - Italy) is subjected to a diffused, continuous kinematic phenomenon. It is shaped into a top-valley gentle slope (circa 11° ), which downgrades directly from the south-side faces of the Northern Apennines summits (1800 meters a.s.l.). On this endangered site are situated a small town and six of its surrounding hamlets. In consequence of the widespread and differential movements at ground level, many buildings and structures are continuously damaged. Institutions, Land-Authorities, as well as the Citizens, are applying their economical efforts in the rehabilitations and the assessment/control of the active phenomena. From the geological and morphological points of view, the topmost sediment is formed by a pliocenic glacial till and its body of widely assorted sediments had been reckoned as a large relict landslide. The loose-soils' thickness spans from few meters up to 90, before of reaching the local bedrock formations (argillites, sandstones, mudstones, ophiolites and diabases in pillows). Former studies have underlined that the main trigger actions are represented by the seasonal rain/snow falls on the watershed and that the kinematic phenomenon is heavily influenced by the subsoil features. The Authors have recently dealt with the characterization and study of this complex landslide [ref. @: the International Association for Mathematical Geosciences (IAMG) Conference, Salzburg (A), September 5-9, 2011 and the 2nd World Landslide Forum, Rome (I), October 3-9, 2011], giving particular attention to both the geotechnical and the hydrological aspects of the site. Since the buried bedrock spatial morphology, depth and steepness have a key role, geophysical and seismic array techniques were used toinvestigate the micro-tremor characteristics and to correlate the emerging data to the geotechnical and geophysical properties of the shallowsediments. Noise measurements were made at more than

  14. A new water permeability measurement method for unsaturated tight materials using saline solutions

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Relative water permeability of material in a radioactive waste disposal is a key parameter to simulate and predict saturation state evolution. In this paper we present a new measurement method and the results obtained for Callovo-Oxfordian (Cox) clay-stone, host rock of the underground Andra laboratory at Bure (Meuse/Haute-Marne). Relative water permeability of such a low permeability rock as Cox clay-stone has been measured up to now by an indirect method. It consists in submitting a rock sample to successive relative humidity steps imposed by saline solutions. The transient mass variation during each step and the mass at hydric equilibrium are interpreted generally by using an inverse analysis method. The water relative permeability function of water saturation is derived from water diffusion coefficient evolution and water retention curve. The proposed new method consists in directly measuring the water flux across a flat cylindrical submitted to a relative humidity gradient. Two special cells have been developed. The tightness of the lateral sample surface is insured by crushing a polyurethane ring surrounding the sample set in an aluminium device placed over a Plexiglas vessel filled with a saline solution. One of the cells is designed to allow humidity measurement in the cell. These cells can also be used to measure the relative humidity produced by a saline solution or by an unsaturated material. During a permeability measurement, the cell with the sample to be tested is continuously weighted in a Plexiglas box in which a saline solution imposes a different relative humidity at the upper sample face. The experimental set-up is shown on Figure 1. The mean permeability of the sample is proportional to the rate of mass variation when steady state is reached. The result of one test is shown on Figure 2(a). Twenty four permeability measurements have been performed on four argillite samples of 15 mm in height and

  15. PHREEQC modelling of concrete/clay interactions in a 2D geometry with explicit effect of porosity evolution on transport properties due to mineralogical changes

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the context of deep repository for radioactive waste, significant use of concrete will be made. This material constitutes a compromise between properties, technical uses and costs. Within the French concepts, concrete will be used to build access structures, drifts as well as waste disposal cells and waste packages for Intermediate Level Wastes (ILW). With this design, concrete will be at the interface with either/both the host rock, Callovo-Oxfordian argillites in our case, and/or the clay plug built with swelling clay such as bentonite. Due to the chemical disequilibrium between concrete and clay, chemical reactions can modify both chemical and physical properties of these materials (e.g. mineralogical composition, diffusion coefficient...). In order to assess the long term behaviour of concrete/clay interfaces and the evolution of their properties with time, predictive modelling have to be performed. The high chemical contrast (e.g. pH or pe at the interface) often leads to problems of numerical convergence. Our own experience showed that PHREEQC is very successful in handling such difficulties in 1D geometry. PHREEQC is also able to handle 2D geometries as presented hereafter thanks to the MIX option as well as feedback on porosity thanks to the MCD option (multi component diffusion). Indeed, 2D simulation of a drift sealing concept developed by Andra was attempted using PHREEQC with the MIX option which allows the use of different transport properties in the different cells. A basic program was developed to generate this complex 2D mesh and another one to treat the outputs under TECPLOTR. The mesh is composed of 3081 cells with a refinement of 3 cm at each interface. Such a simulation was already conducted under ALLIANCES geochemistry transport tools, but in our cases the mesh refinement and the chemistry of the system are extended and the feedback on porosity is now considered. Furthermore, the new multi

  16. Seismic properties of rocks affected by hydrothermal alteration: a case study from the Lalor Lake VMS mining camp

    Science.gov (United States)

    Miah, K.; Bellefleur, G.; Schetselaar, E.

    2013-12-01

    are essential to determine whether any 2D/3D active survey would be worth conducting. In situ density and velocity logs, and thus, acoustic impedance provide first order control on reflectivity of various lithologies. In this abstract, we analyzed well logs from 12 drill holes geographically located in the northern Manitoba, Canada, in an attempt to characterize lithologies based on their seismic properties. Velocities, density, acoustic impedance and Poisson's ratio of major lithologies were compared among each other. Massive sulphide and Diorite have higher average acoustic impedance than the others. Our quantitative analysis suggests that alteration has considerable effect on overall acoustic impedance of Argillite, Felsic Volcanic and Stringer Sulphide rocks. This can be useful in selecting values of model parameters for seismic wave propagation simulation, which can be used to compare with seismic survey data. In addition, core sample analysis from the same drill holes aided our understanding of mineralization, alteration, and overall composition of different rocks under consideration.

  17. H, HM, and THM-C processes in natural barriers

    International Nuclear Information System (INIS)

    This session gathers 30 articles (posters) dealing with: the three Dimensional analyses of combined gas, heat and nuclide transport in a repository considering coupled thermo-hydro geomechanical processes; the experimental study on the thermo-hydro-mechanical behaviour of boom clay; hydraulic in-situ measurements in the Opalinus clay in the frame of a heater test performed at the Mont Terri URL; the hydro-mechanical behaviour of natural boom clay in controlled-suction tests; a constitutive approach to address the thermal and hydric impacts in the concept of deep radioactive waste repositories; the numerical analysis on stability of boom clay tunnel by shield construction; a thermo-hydro-mechanical model for clay in unsaturated conditions; the 3D modelling of TER experiment accounting for fully anisotropic thermo-poro-elastic behaviour; the hydro-mechanical modeling of shaft excavation in Meuse/Haute-Marne laboratory; the modelling of drying damage in engineered and natural clay barriers for nuclear waste disposal; the elasto-viscoplastic behaviour of Meuse/Haute-Marne argillite: laboratory tests and modelling; the long-term behaviour of a lime treated soil under percolation conditions; the stress redistribution and hydro-mechanical effects due to excavation and drilling operations in TER experiment; a thermodynamic model on swelling of bentonite buffer and backfill materials; the 3D analysis of a heating test in the Opalinus clay; the THM analysis of a 'mock-up' laboratory experiment using a double-structure expansive model; the measurement of the effect of re-confinement on rock properties around a slot; a laboratory Study of desaturation - re-saturation effects on a clay-stone; the deformation induced by dissolution of salts in porous media; the bentonite swelling pressure in pure water and saline solutions; the mineralogy and sealing properties of various bentonites and smectite-rich clay materials; the evaluation of the geochemical processes occurring in the

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

    International Nuclear Information System (INIS)

    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 10-12-10-13 m2. 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 10-16-10-21 m2 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 magnitude down to very low levels

  19. Hydraulic sealing of fractured argillaceous rocks

    International Nuclear Information System (INIS)

    samples (diameter/length = 70/20 mm) under two temperatures (20 C and 90 C). The hydraulic sealing of fractures was determined by measuring Bure synthetic pore water flow through specimens placed in percolation cells. Confinement is obtained by the swelling pressure developed by the clay content of the sample. After a 2 months phase dedicated to water saturation, the first flux measurement are made on the intact specimen. Once the water flux stabilised, the clay specimen is fractured directly into the percolation cell by applying a shear stress on the sample. Then, water flux evolution is measured on the damaged sample. The flux of water percolating through the intact specimen has been determined under a pressure gradient (ΔP) of 10 bars. Results show that the water flux (Q) is almost constant on intact clay over the first period and close to 3.8 10-13 m3s-1 (∼1.4 μL/h). Just after fracturing, an increase of water flux (multiplied by three) has been observed followed by a slow decrease over 150 days. Clay permeability (Kint) can be derived according to the Darcy law. After 5 months, water permeability of the fractured specimen is closed to the one obtained with the clay before mechanical damaging. Those results show that hydraulic sealing of COX argillite may occur within few months at room temperature, under a mechanical confinement. Future work is scheduled to test different kind of fracturing (variable apertures, fracture network, several level of confining pressure...) and to obtain results more representatives of the different observations made on the in situ EDZ. (authors)

  20. Role of sulphide species on the behaviour of carbon steel envisioned for high-level radioactive disposal: interaction between sulphide and corrosion products

    International Nuclear Information System (INIS)

    This PhD work deals with the nuclear waste disposal. In France, it is envisaged by Andra (French national radioactive waste management agency) that high-level radioactive wastes will be confined in a glass matrix, stored in a stainless steel canister, it self placed in a carbon steel overpack. The wastes will then be stored at a depth of ∼500 m in a deep geological repository, drilled in a very stiff (indurated) clay (argillite) formation. The kinetics of corrosion expected for the overpack in this disposal concept are low and will stay low if the somehow protective rust layer that will develop initially on the steel surface remains undamaged. Local changes of the physico-chemical conditions may however degrade this layer and induce accelerated kinetics of corrosion. In particular, the growth of sulphate reducing bacteria (SRB) close to the steel overpack cannot be excluded and the sulphide species these micro-organisms produce may modify the corrosion process. The aim of this work was then to achieve a better understanding of the corrosion system constituted with steel, its rust layer mainly made of siderite FeCO3, and a sulphide-containing electrolyte. First, it proved necessary to characterise the iron sulphides involved in the corrosion processes by Raman micro-spectroscopy so as to study their formation and transformation mechanisms in various conditions of Fe(II) and S(-II) concentration, pH, temperature and aeration. It could be demonstrated that the Raman spectrum of mackinawite FeS, the compound that precipitated in any case from dissolved Fe(II) and S(-II) species with the experimental conditions considered here, depended on the crystallinity and oxidation state. Moreover, the mechanisms of the oxidation of mackinawite into greigite Fe3S4 in acidic anoxic solutions at 80 C could be described. Finally, iron sulphides, often present on archaeological artefacts, could be identified using Raman micro-spectroscopy. The compounds present were mainly

  1. The oxidation of mackinawite (FeS): a Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Bourdoiseau, J.A.; Jeannin, M.; Sabot, R.; Refait, Ph. [La Rochelle Univ., Lab. d' Etude des Materiaux en Milieux Agressifs, EA 3167, 17 (France); Bourdoiseau, J.A. [ANDRA, 92 - Chatenay Malabry (France)

    2009-07-01

    Full text of publication follows: This study relates to the problem of nuclear wastes disposal. In France, it is envisaged that high-level radioactive wastes will be confined in a glass matrix, stored in a stainless steel canister, itself placed in a carbon steel overpack. The wastes will then be stored at a depth of {approx}500 m in a deep geological disposal, drilled in a very stiff (indurated) clay (argillite) formation. Localised leaks of sulphide from the environment, produced for instance by sulphate reducing bacteria, could occur. In order to estimate the probability of a localised corrosion phenomenon induced by such sulphide species on the steel surface of the overpack, the mechanisms have to be understood first. For such a study, micro-Raman spectroscopy is a unique technique since it can analyse corrosion products on local zones as small as {approx}2*2 {mu}m. Moreover, a recent work revealed that Raman analysis could provide information about the degrees of crystallisation, dehydration and oxidation of mackinawite FeS [1]. This iron-sulphur compound is the one that precipitates from dissolved Fe(II) and S(-II) species and is consequently the first corrosion product to form on steel in the presence of sulphide, typically in H{sub 2}S containing atmospheres or Na{sub 2}S electrolytes. It is sensitive to the oxidising action of O{sub 2} and can persist for long periods of time only under reduced conditions. In the presence of O{sub 2}, mackinawite can be transformed into greigite Fe{sub 3}S{sub 4}, into elemental sulphur and Fe(III) oxy-hydroxides and/or magnetite Fe{sub 3}O{sub 4} [2]. Mackinawite samples were oxidized by various methods so that different oxidation degrees could be obtained. A complete oxidation under large oxygen flows led to lepidocrocite {gamma}-FeOOH and elemental sulphur {alpha}-S{sub 8}. Partial oxidation led to a progressive modification of the Raman spectrum of the iron-sulphur compound. After a slight oxidation, the spectrum was

  2. Ten years of experience in technology development... What use for the Cigeo project?

    International Nuclear Information System (INIS)

    Since 2003, Andra (the French public body in charge of radioactive waste management) has been working on the progressive technological development of waste storage containers, package handling mechanical prototypes, excavation techniques and support lining of underground openings at the Bure Underground Laboratory (URL) site, in order to evaluate the feasibility of constructing and operating a Deep Geological Repository (DGR aka Cigeo), in the Callovian-Oxfordian clayish formation (the ''Argillites''), likely to receive as of 2025-2030 the first of many intermediate and high-level long lived wastes, at a 500m depth. The Cigeo Project, which has now entered into an intense engineering development phase, must take into account all the data, knowledge and experience gathered over more than 10 years of technical research. The spectrum of activities concerned encompasses a wide array of subjects such as the return of experience gathered from the shaft sinking operations, the drift excavation operations (via means of rock hammer, road header and tunnel boring machine) and the subsequent lining support of the horizontal drifts (via metal arches, mesh, rock bolts, shotcrete, cast concrete and wedges). The story of coring, drilling and casing vertical, slanted or horizontal boreholes is also of interest. The implementation and evaluation of sealing technologies or hydraulic cut-offs must be integrated in the design. The construction and qualification in 3 campaigns of 9 families of concrete containers and 3 categories of carbon steel overpacks also come as input data. The design, construction and testing of 3 package emplacement systems, the implementation of 2 waste retrievability tests are accounted for in the studies ongoing. Finally the collation of environmental and geotechnical data on the excavated material (likely to be re- used for opening backfilling at time of repository closure) will help to minimize the acreage, volume and visual impact of

  3. Organic matter and hydrogen as electron donor for SRB and IRB activities in a clayey medium

    International Nuclear Information System (INIS)

    potentially be used as electron donor. For that purpose, DOM was extracted from crushed rock under anoxic conditions with solutions representative of Tournemire pore water for 36 hours. The factors influencing DOM extraction, such as extraction time, solid-to-liquid ratio, exposure to oxygen gas and temperature, were tested according to the same experimental methodology as previously applied to the OM of the Callovo-Oxfordian clay-stone. The DOM and the low molecular weight organic acids were determined, respectively, by Total Organic Carbon (TOC) analyzer and Ion Chromatography (IC). The dissolved organic carbon (DOC) was identified as fumarate, acetate, lactate, formate and propionate, so that only 35 % are low molecular weight organic acids. These organic acids (propionate excepted) have also been identified in pore water samples directly collected from Tournemire argillite. In order to study the role of hydrogen and DOM from Tournemire clay on bacterial activity and growth, batch experiments were performed in presence of a SRB Thermo desulfovibrio hydrogeniphilus, an IRB Thermo toga subteranea strain SLT 1 and a mixed culture of both species. Three sets of experiments were launched: the first one under hydrogen, the second one with DOM and the third one with both DOM and hydrogen. The culture medium consists of a solution representative of Tournemire pore water and essential nutrients for bacterial growth. DOM is added as a solution obtained by equilibration of synthetic pore water with crushed rock material at a solid-to-liquid ratio of 1500 g.L-1 for one week. Control experiments without bacteria were carried out under the same conditions. Hydrogen partial pressure was periodically monitored by gas chromatography, DOC and organic acid in the liquid phase by TOC analyzer and IC. Results are discussed with respect to bacterial activity (SRB, IRB and both species) and consequently, to the influence of the different electron donors (hydrogen, OM and both). (authors)

  4. Modeling the evolution of cesium diffusion front in argillaceous rock: effects of the 3D microstructure

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Argillaceous rocks are currently being proposed as potential host rocks for radioactive waste repository in deep geological formations. It is important for performance assessment to determine and understand on a fundamental level the transport properties of such rocks. Clay materials are characterized by low hydraulic conductivities and, due to the absence of fractures and fissures, diffusion is assumed to be the main transport mechanism. Transport parameters of natural porous media have been studied mainly in terms of small-scale lab experiments or in larger-scale field tracer tests under near in-situ conditions. The transport parameters for diffusion are generally interpreted in the frame of Fick's laws, assuming a homogeneous porous medium. However, clay formations are composed of several mineral phases and are naturally heterogeneous. At the micrometer scale, the main heterogeneity is the spatial distribution of the minerals in the rock. However, the influence of the microstructure i.e., the spatial mineral distribution, on solute transport is still an open issue. Spatially highly-resolved information within natural rock samples regarding 3D mineral distributions, as well as 3D contaminant distributions, can be obtained from synchrotron-based microtomography. In this study, we present the diffusion of cesium (Cs) in small cylinders (diameter: 2.8 mm) of Opalinus clay and Callovo-Oxfordian argillite, potential host rocks in Switzerland and France. The microstructure of the rock was investigated, as well as the temporal and spatial evolution of the 3D cesium distribution at regular intervals during a 48 hours campaign with synchrotron-based micro-tomography. The calculated diffusion fronts were compared with the experimental ones. The study showed that the cesium distribution is related to the clay distribution in the rock. As a consequence, only the clay fraction of the rock was considered as an anisotropic

  5. The Genesis of Precious and Base Metal Mineralization at the Miguel Auza Deposit, Zacatecas, Mexico

    Science.gov (United States)

    Findley, A. A.; Olivo, G. R.; Godin, L.

    2009-05-01

    The Miguel Auza mine located in Zacatecas State, Mexico, is a vein-type polymetallic epithermal deposit hosted in deformed argillite, siltstone and, greywacke of the Cretaceous Caracol Formation. Silver-rich base metal veins (0.2 m to >1.5 m wide) are spatially associated with the NE-striking, steeply SE- dipping (70-80°) Miguel Auza fault over a strike length of 1.6 km and a depth of 460 m. A 2 km2 monzonitic stock located in the proximity of the mineralized zones, has previously been interpreted as the source of the mineralizing fluids. Four distinct structural stages are correlated with hydrothermal mineral deposition: (I) The Pre-ore stage is characterized by normal faulting, fracturing of host rock, and rotation of bedding planes. This stage consists of quartz, illite, chlorite, +/- pyrite alteration of sedimentary wall rocks. (II) The Pyrite-vein stage is associated with reverse-sense reactivation of early normal faults, dilation of bedding planes/fractures, and deposition of generally barren calcite + pyrite veinlets. (III) The Main-ore stage is related to the development of reverse-fault- hosted massive sulphide veins. During this stage three phases of mineral deposition are recorded: early pyrite and arsenopyrite, intermediate chalcopyrite, pyrite, arsenopyrite, and base metals, and late base metals and Ag-bearing minerals. Associated gangue minerals during the main ore stage are quartz, muscovite, calcite and chlorite. (IV) The Post-ore stage involves late NW-SE striking block faulting, brecciation and calcite veining. Later supergene oxidation of veins led to deposition of Fe-oxides and hydroxides, commonly filling fractures or replacing early-formed sulphide assemblages. The various vein types display classic epithermal textures including open space filling, banding, comb quartz and brecciation. The Ag-bearing minerals comprise pyrargyrite [Ag3(Sb,As)S3], argentotennantite [(Cu,Ag)10(Zn,Fe)2(Sn,As)4S13], polybasite-pearceite [(Ag,Cu)16(Sb,As)2S11], and

  6. Raw materials exploitation in Prehistory of Georgia: sourcing, processing and distribution

    Science.gov (United States)

    Tushabramishvili, Nikoloz; Oqrostsvaridze, Avthandil

    2016-04-01

    Study of raw materials has a big importance to understand the ecology, cognition, behavior, technology, culture of the Paleolithic human populations. Unfortunately, explorations of the sourcing, processing and distribution of stone raw materials had a less attention until the present days. The reasons of that were: incomplete knowledge of the archaeologists who are doing the late period archaeology (Bronze Age-Medieval) and who are little bit far from the Paleolithic technology and typology; Ignorance of the stone artifacts made on different kind of raw-materials, except flint and obsidians. Studies on the origin of the stone raw materials are becoming increasingly important since in our days. Interesting picture and situation have been detected on the different sites and in different regions of Georgia. In earlier stages of Middle Paleolithic of Djruchula Basin caves the number of basalt, andesite, argillite etc. raw materials are quite big. Since 130 000 a percent of the flint raw-material is increasing dramatically. Flint is an almost lonely dominated raw-material in Western Georgia during thousand years. Since approximately 50 000 ago the first obsidians brought from the South Georgia, appeared in Western Georgia. Similar situation has been detected by us in Eastern Georgia during our excavations of Ziari and Pkhoveli open-air sites. The early Lower Paleolithic layers are extremely rich by limestone artifacts while the flint raw-materials are dominated in the Middle Paleolithic layers. Study of these issues is possible to achieve across chronologies, the origins of the sources of raw-materials, the sites and regions. By merging archaeology with anthropology, geology and geography we are able to acquire outstanding insights about those populations. New approach to the Paleolithic stone materials, newly found Paleolithic quarries gave us an opportunities to try to achieve some results for understanding of the behavior of Paleolithic populations, geology and

  7. Zheltozems of Russia: Micromorphology, clay minerals, and pedogenetic analysis Zheltozems de Rusia: micromorfología, minerales de la arcilla y análisis edafogenético Zheltozems da Russia: Micromorfología, Minerais de Argila e Análise Pedogenética

    Directory of Open Access Journals (Sweden)

    Maria Gerasimova

    2013-11-01

    Full Text Available Zheltozems (literally "yellow earths" that can be classified as Acrisols, Alisols, or Ultisols, occupy very small areas in Russia; they are strongly modified by human activities. The unchanged profiles are preserved only locally, in particular, in the Sochi arboretum. When compiling the soil map of the arboretum, different Zheltozems were described on gentle and moderately steep slopes and diverse parent materials: calcareous claystone and its heavy-textured derivates. The micromorphology of three characteristic Zheltozem profiles developed on these different parent materials was also studied. The features that they have in common are the following: in all profiles, a specific heavy-textured Bw, or BM 'metamorphic' horizon was identified with a certain set of micromorphological properties: a massive microstructure with fine planes merging into deformed biogenic pores, a monic groundmass with few silt grains that are sometimes oriented, and impregnative iron-oxides pedofeatures. The b-fabric was defined as stipple speckled, poro- and granostriated, locally (monostriated ressembling stress coatings. There are almost no clay coatings except for very few fine internal ones that are light yellow and homogeneous; clay and iron pseudomorphs (alteromorphs occur over some skeleton grains. Many of these properties are related to the clay mineral composition. There are varying quantities of smectites and kaolinite-smectites, whereby the former increase with depth. The presence of expanding minerals is known to contribute to the disintegration of coatings. Remnants of these are observed in typic iron-manganic nodules. In terms of WRB, this horizon is an intergrade between cambic and argic, which is not accounted for in soil diagnostics. As three different Zheltozems are studied in the same area, the following genesis of this specific intergrade can be given. The saprolite in one of the profiles is composed of fragments of weathered calcareous argillites

  8. Performance assessment methodology and preliminary results for low-level radioactive waste disposal in Taiwan

    International Nuclear Information System (INIS)

    Sandia National Laboratories (SNL) and Taiwan's Institute for Nuclear Energy Research (INER) have teamed together to evaluate several candidate sites for Low-Level Radioactive Waste (LLW) disposal in Taiwan. Taiwan currently has three nuclear power plants, with another under construction. Taiwan also has a research reactor, as well as medical and industrial wastes to contend with. Eventually the reactors will be decomissioned. Operational and decommissioning wastes will need to be disposed in a licensed disposal facility starting in 2014. Taiwan has adopted regulations similar to the US Nuclear Regulatory Commission's (NRC's) low-level radioactive waste rules (10 CFR 61) to govern the disposal of LLW. Taiwan has proposed several potential sites for the final disposal of LLW that is now in temporary storage on Lanyu Island and on-site at operating nuclear power plants, and for waste generated in the future through 2045. The planned final disposal facility will have a capacity of approximately 966,000 55-gallon drums. Taiwan is in the process of evaluating the best candidate site to pursue for licensing. Among these proposed sites there are basically two disposal concepts: shallow land burial and cavern disposal. A representative potential site for shallow land burial is located on a small island in the Taiwan Strait with basalt bedrock and interbedded sedimentary rocks. An engineered cover system would be constructed to limit infiltration for shallow land burial. A representative potential site for cavern disposal is located along the southeastern coast of Taiwan in a tunnel system that would be about 500 to 800 m below the surface. Bedrock at this site consists of argillite and meta-sedimentary rocks. Performance assessment analyses will be performed to evaluate future performance of the facility and the potential dose/risk to exposed populations. Preliminary performance assessment analyses will be used in the site-selection process and to aid in design of the

  9. Modelling of long term geochemical evolution and study of mechanical perturbation of bentonite buffer of a KBS-3 repository

    Energy Technology Data Exchange (ETDEWEB)

    Marsal, Francois; Pellegrini, Delphine; Deleruyelle, Frederic; Serres, Christophe (French Inst. for Radiological Protection and Nuclear Safety (IRSN), Fontenay-aux-Roses (FR)); Windt, Laurent de (Ecole des Mines de Paris, Paris (FR))

    2008-03-15

    simulated intrusion of oxidizing waters lead to a limited perturbation, i.e. localized within bentonite near the fracture plane level. Actually, the calculated evolutions are relatively slow, so that in some cases the buffer remains in a transient stage over the whole simulation period and thus could turn heterogeneous in geochemical properties. Regarding the effect of temperature, a heterogeneous evolution is again observed, with moderate to slight dissolution-precipitation reactions either on the inner or outer border of the buffer (warmer and cooler zones) depending on the accessory minerals. These main trends in bentonite geochemical evolutions are in good agreement with the results presented in SR-Can and in Arcos et al., though some discrepancies have been pointed out, that can be explained by differences in modelling input data (mainly regarding log K values). Finally, issues in terms of processes and data would worth being further investigated as they might have a significant influence on bentonite evolutions, such as the thermohydraulic coupling of processes during the initial transient phase or the stability of montmorillonite. PART II: Elements of the SR-Can project relative to piping and erosion phenomena of bentonite components of a KBS-3 repository are analysed with regard to the experience feedback available at IRSN and consisting in experimental results obtained on samples at the UJF-Grenoble between 2000 and 2004. A synthesis of these tests is presented, with a closer attention to the Argillite/Bentonite tests during which phenomena of erosion occurred. The reference evolution of a KBS-3 repository, the resaturation and swelling kinetics of backfills and buffers and the possibility for a buffer to swell upwards the backfill have been considered. According to the reviewed documents, IRSN notes that the SR-Can project tackles the piping and erosion phenomena with local modellings and 'rough estimates', the latter being based on 3 &apos

  10. Diffuse transport in clay media: μm to nm scale characterization of pore space and mineral spatial organization

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the framework of radioactive waste repository, clay-rock formations are foreseen as barrier materials due to their diffusion properties. In clay materials, the dominant transport mode is diffusive and depends mainly on various parameters such as the mobility of the species in water, the accessible porosity, the pore space geometry and the retardation as a result of reactions such as sorption or ion exchange. In this way, the European CATCLAY project (EURATOM FP7), in the context with research on transport in porous materials, was proposed to describe the cation migration processes in natural clay-rocks. The project is structured along 3 RTD work packages, combining modeling and experimental studies from a simpler, analogous system (monophasic compacted clay system) to clay-rocks (Callovo-Oxfordian argillites, Opalinus Clay and Boom Clay). Part of this experimental studies focuses on small scale structure (μm - nm) property of rocks in order to determine how the spatial distribution of mineral and pores at small scales can influence diffusion driven transport of sorbing cations. The present study focuses on compacted illite properties (simpler analogous system) in hopes to extent this study to the natural clay-rock formation. Illite was chosen by the way that is the main constituent of clay-rock. Compacted illite material represents thus an analogy with the clay matrix constituting clay-rocks. Our approach is mainly based on imaging the small scale structural organization of compacted illite material and analyzing the obtained images in order to extract information on pore space and mineral spatial distribution. Techniques for imaging the texture of illite material like water saturated, in compacted state, were first developed. The first step was to improve classic resin impregnation method in order to preserve the texture without losing the clay confinement and modifying the pore space geometry. This has been

  11. Non disturbing characterization and quantification of natural organic matter (NOM) contained in clay rock pore water by mass spectrometry using electro-spray and atmospheric pressure chemical ionization modes

    International Nuclear Information System (INIS)

    formation is of great importance. In this context, establishing accurate sequencing of structural units for the DOM shall be attempted. The present work is focused on small organic molecules that are present in the COx formation and that could also play a key role in the migration processes. It would be valuable to develop rapid analytical methods that require only a small sample volume and minimal pretreatment. Of particular importance is the ability to analyze bulk pore water samples as opposed to samples subjected to specific extraction techniques, fractionation, and/or concentration. Mass Spectrometry with either the Electro-Spray or the Atmospheric Pressure Chemical Ionization modes has been proved to be a powerful tool for aquatic humic substances since it allows the determination of the molecular weight distribution and the access to the different molecular weights. In this study, we have employed ESI-MS and APCI-MS to identify the chemical composition of NOM contained in the pore water from the argillite clay rock. Due to the very small quantities of COx pore water available from boreholes, these techniques are thus very suitable. The DOM in pore water has never been characterized on a well preserved pore water sample. The following aspects were considered in the present work: (1) the use of either ESI or APCI to select the most appropriated mode of ionization for providing the best information depending on the class of compound examined (2) a unique and original experimental process developed to get pore water from a core sample (3) the determination of concentration of dissolved organic matter and the evaluation of the organic matter maturity by Excitation-Emission Matrix (EEM) spectroscopy and (4) the application of the proposed instrumental methods for the characterization of organic components from natural pore waters. For the first time to our knowledge, a quite exhaustive inventory of the small organic compounds presents is given without proceeding to any

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. Influence of osmotic processes on the excess-hydraulic head measured in the Toarcian/Domerian argillaceous formation of Tournemire

    International Nuclear Information System (INIS)

    able to take into account the effect of multi-ionic solutions, i.e. nearest than the natural waters composition, and, thus, to constrain better the chemo-osmotic efficiency. Thermo-osmosis process is poorly characterized so that no satisfactory macroscopic expression to calculate the thermo-osmotic permeability kT was available nor thermo-osmotic experiments performed on natural shales, so far. This process is interpreted as being related to changes properties of water sorbed at clay minerals surface compared with bulk water. A thermo-osmotic permeability predictive model is proposed here, based on the modifications of the hydrogen bounds associated with water molecules located at the vicinity of the solid surface. Input parameters of this model only consist in petrophysical parameters and medium conditions (pore water concentration and temperature). Chemical osmosis and thermo-osmosis experiments were performed on Tournemire argillite samples and in a test interval equipped borehole at the Tournemire URL. These experiments have consisted in inducing a concentration or temperature gradient across a sample for the laboratory experiments and between the borehole test interval and the formation for the in situ experiments. Osmotic flows were identified by the interpretation of the pressure evolution in the test interval using a hydro-thermo-chemo-mechanical model based on the mass balance equation sand the coupled-flow equations. Inversion of the measured pressure signals allowed identifying a chemo-osmotic efficiency ranging between 0.014 and 0.31 and a thermo-osmotic permeability kT ranging between 6 x 10-12 and 2 x 10-10 m2K-1s-1 for the Tournemire clay-rock. In parallel to the characterization of the osmotic processes in the argillaceous formation of Tournemire, pore water composition and temperature profiles were established. Temperature profile was obtained by direct measurement in different boreholes. Pore water composition profile was calculated by a geochemical

  14. 辽吉地区含硼岩系中斜长角闪岩地球化学%GEOCHEMISTY OF PLAGIOCLASE-AMPHIBOLITE OF THE BORON-BEARING ROCK SERIES IN LIAONING AND JILIN PROVINECES AND ITS ORIGIN

    Institute of Scientific and Technical Information of China (English)

    肖晔; 刘长学

    2009-01-01

    plagioclase-amphibolite in the east of Liaoning province is distinctly higher than that in the south of Jilin provinces area; moreover, boron contents in various plagioclase-amphibolite is obviously high. But B, Cr and Ni contents in the east of Liaoning are distinctly higher those in the south of Jili narea,displaying typical features of sea-facies mantle magma; while in the south of Jilin area just shows the features of metamorphic hydrothermal reforming. REE geochemistry of plagioclase-amphibolite in eastern Liaoning province suggests mantle-derived magma, which was then reformed by hydrothermal fluid; whereas that in the south of Jilin shows features of crustal sedimentation. REE distribution pattern of boron-bearing plagioclase-amphibolite is similar to that of leucoleptite, indicating the both may be magmatic in origin. However, REE enrichement patterns of tourmaline granulitite, biotite granulitite and migmatite indicate a metamorphized sea-facies sedimentary rock origin. Migmatitization and metamorphic hydrothermal fluid also have distinct reconstructing effect on the protolith. The geochemistry of plagioclase-amphibolite obviously show that protolith formed under a Na-rich and B-rich sea faices environment and protolith was mainly composed of seafacies Mg-rich tholeiite and seafaices argillite.

  15. In situ and laboratory investigations of fluid flow through an argillaceous formation at different scales of space and time, Tournemire tunnel, southern France

    Science.gov (United States)

    Boisson, Jean-Yves; Bertrand, Lucien; Heitz, Jean-François; Golvan, Yann Moreau-Le

    2001-01-01

    In the context of a research and development program on waste disposal, an experimental site (Tournemire tunnel, Aveyron, France) was selected by the French Institute for Nuclear Protection and Safety (IPSN) in order to undertake studies on potential fluid flow at different scales of space and time within a 250-m-thick argillaceous formation. The argillite has a low natural water content ( 3-5%) and very low radii access porosity. Diffusion (tritiated water) coefficients (1×10-12 to 2×10-11 m2/s) and hydraulic conductivities derived from different types of laboratory tests (10-14 to 10-13 m/s) are characteristics of a very low-permeable rock. In situ hydraulic tests (including long-term hydraulic-head measurements) were used to obtain values for hydraulic head and hydraulic conductivity at a scale of 1-10 m (10-13 to 10-11 m/s). Despite uncertainties on these data (due to a scale factor, presence of fissures, and possible artefacts due to hydro-chemo-mechanical coupling), it is expected that fluid flow is essentially governed by diffusion processes. Identification of possible natural flows at larger scales of time and space was investigated using natural isotopic tracers from interstitial fluids. Modelling, based on the deuterium profile along the clay formation and assuming pure diffusion processes, provides estimations of possible flow times. However, lack of knowledge concerning the past geological evolution of the site and the possible role of a fracture network do not permit reduction of uncertainties on these estimations at this stage. Résumé. Dans le cadre de son programme de recherche et développement sur les stockages de déchets, un site expérimental (tunnel de Tournemire, Aveyron, France) a été sélectionné par l'Institut de Protection et Sûreté Nucléaire (IPSN) pour conduire des études sur les possibilités de transferts de fluides à différentes échelles de temps et d'espace au sein d'une formation argileuse de 250 m d'épaisseur. L

  16. In situ and laboratory investigations of fluid flow through an argillaceous formation at different scales of space and time, Tournemire tunnel, southern France

    Science.gov (United States)

    Boisson, Jean-Yves; Bertrand, Lucien; Heitz, Jean-François; Golvan, Yann Moreau-Le

    2001-01-01

    In the context of a research and development program on waste disposal, an experimental site (Tournemire tunnel, Aveyron, France) was selected by the French Institute for Nuclear Protection and Safety (IPSN) in order to undertake studies on potential fluid flow at different scales of space and time within a 250-m-thick argillaceous formation. The argillite has a low natural water content ( 3-5%) and very low radii access porosity. Diffusion (tritiated water) coefficients (1×10-12 to 2×10-11 m2/s) and hydraulic conductivities derived from different types of laboratory tests (10-14 to 10-13 m/s) are characteristics of a very low-permeable rock. In situ hydraulic tests (including long-term hydraulic-head measurements) were used to obtain values for hydraulic head and hydraulic conductivity at a scale of 1-10 m (10-13 to 10-11 m/s). Despite uncertainties on these data (due to a scale factor, presence of fissures, and possible artefacts due to hydro-chemo-mechanical coupling), it is expected that fluid flow is essentially governed by diffusion processes. Identification of possible natural flows at larger scales of time and space was investigated using natural isotopic tracers from interstitial fluids. Modelling, based on the deuterium profile along the clay formation and assuming pure diffusion processes, provides estimations of possible flow times. However, lack of knowledge concerning the past geological evolution of the site and the possible role of a fracture network do not permit reduction of uncertainties on these estimations at this stage. Résumé. Dans le cadre de son programme de recherche et développement sur les stockages de déchets, un site expérimental (tunnel de Tournemire, Aveyron, France) a été sélectionné par l'Institut de Protection et Sûreté Nucléaire (IPSN) pour conduire des études sur les possibilités de transferts de fluides à différentes échelles de temps et d'espace au sein d'une formation argileuse de 250 m d'épaisseur. L

  17. Soixante années de recherches en coopération sur l'érosion hydrique et la lutte antiérosive au Maghreb

    Directory of Open Access Journals (Sweden)

    Mohamed Mazour

    2012-05-01

    erosion damages by saturation of the topsoil than usual rains. In Algeria, A. DEMMAK found that the wadis solid transport is related mainly to the extension in the watersheds of argillite, marl and shale outcrops.Since 1985, a research team of INRF and IRD realised, in Algeria, investigations on SWC techniques efficiency, developed intensive agro-ecosystems valorising better the ground and labour, restored gullies with various sills models and various plants and trees valorising the badlands: they called the system "GCES". In Morocco, teams of ENFI foresters, Rabat University geographers and IRD have described and analysed 30 SWC systems developed by farmers living in the Atlas mountains. IRD with the Faculty of Marrakech developed a methodology using teledetection, rainfall infiltrometer on 1 m2, surface status and GIS in order to spatialise erosion risks and types of SWC managements necessary in a mountainous watershed of 270 km2.