Measuring the permeability of Eleana argillite from area 17, Nevada Test Site, using the transient method

International Nuclear Information System (INIS)

Lin, W.

1978-01-01

Using the transient method, we determine the permeability of high-quartz Eleana argillite from the Nevada Test Site as a function of effective pressure. By comparing calculated and observed pressure decay in the upstream reservoir, we have determined the permeability of intact and fractured specimens at effective pressures ranging from 1.0 to 24.0 MPa. Over this pressure range, Eleana argillite has a low permeability (10 -16 to 10 -19 cm 2 ) when intact and a higher permeability (10 -12 to 10 -17 cm 2 ) with one induced through-going fracture

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

Energy Technology Data Exchange (ETDEWEB)

Croise, J. [Colenco Power Engineering AG, Groundwater Protection and Waste Disposal, Baden (Switzerland); Vinsotz, A. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), Lab. de Recherche Souterrain RD960, 55 - Bure (France); Noya, D. [British Geological Survey, Kingsley Dunham Centre, Nottingham NG (United Kingdom)

2005-07-01

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)

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)

Liu, Jiang-Feng

2013-01-01

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 P gas 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)

Physicochemical aspects of decomposition of silica-alumina ores of argillites and green clays of Chashma-Sang Deposit of the Republic of Tajikistan by hydrochloric and nitric acids

International Nuclear Information System (INIS)

Kayumov, A.M.

2018-01-01

The purpose of work is to study the processes of decomposition of silica-alumina ores of argillites and green clays of Chashma-Sang Deposit of the Republic of Tajikistan by hydrochloric and nitric acids in temperature interval 20-98 deg C with the using of methods of selective extraction of valuable materials; elaboration of rational conditions of decomposition of raw material. Physicochemical properties of initial aluminium comprising ores, intermediate and final products of processing of argillites and green clays have been studied. Kinetic parameters of processes at acidic decomposition of argillites and green clays have been studied as well. The kinetic parameters of processes of decomposition of green clays and argillites by nitric and hydrochloric acids have been calculated. The flowsheet of complex processing of green clays and argillites of Chashma-Sang Deposit has been elaborated.

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

International Nuclear Information System (INIS)

Aublive-Conil, N.

2003-03-01

The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

Contribution to a hydro-chemo-mechanical multi-mechanisms model based on the multi-scale and multi components structure of Callovo-Oxfordian argillites: experiments and modelling

International Nuclear Information System (INIS)

Robinet, J.C.; Trinh, M.H.; Imbert, C.

2010-01-01

Document available in extended abstract form only. The fundamental features of the Callovo Oxfordian argillite, namely the structure and the pore size distribution are considered to propose a model consistent with its mechanical behavior. The model deals with the main mechanisms selected: damage, plasticity and swelling. Structure of Argillites as fundamental base of mechanical behavior Callovian-Oxfordian argillites present specific characteristics: - a strong mineralogical heterogeneity made up from 23% to 25% of quartz, 20% to 27% of carbonate, 40% to 50% of argillaceous minerals and 5% to 10% various mineral; - a low porosity comprised between 12 to 15%, associated with the following pore size distribution: 14% of nano-pores, majority 81% of meso-pores and 5% of macro-pores; - a low Biot coefficient, around 0.6; - no cementing (within the meaning of a concrete). Four basic mechanisms are considered likely to explain the structure of argillite in place: - mechanical consolidation obtained by increasing external stress, - chemical consolidation by reduction in dielectric constant (leaching of chlorides), - thermal consolidation, - filling of the macro-porosity by precipitation of a carbonated phase (calcite). Experimental tests were performed to evaluate the weight of these mechanisms. Results show that mechanic and thermal consolidations, in the fields of stress and temperature encountered in situ by argillite during geological history, and chemical consolidation could not alone explain the state the high density without macro porosity. An assumption advanced to explain is the filling of macro porosity by non argillaceous mineral precipitation, in particular calcite that would confer to in situ argillite an apparent over-consolidation from a mechanical point of view. This assumption is partially validated by some experiments: - Percolation tests were made with hydrochloric acid on bulky and sound argillite to remove the carbonates in the macro-porosity; they

Modeling Cl- concentration and δ37Cl profiles in pore water across a 250 m-thick indurated argillite at the Tournemire URL (France)

International Nuclear Information System (INIS)

Le Gal La Salle, Corinne; Rebeix, Romain; Lancelot, Joel; Matray, Jean-Michel; Bensenouci, Fethic; Michelot, Jean-Luc; Dauzeres, Alexandre; Wittebroodt, Charles; Frape, Shaun; ShouakarStash, Orphane

2013-01-01

Dissolved chloride in argillite pore water has been studied as a natural analogue for radionuclides potentially released from radioactive waste disposal. The Tournemire URL intersects impervious and compacted argillite. A previously obtained chloride concentration profile of intact rock is symmetric with a maximum concentration of 0.6±0.1 g/L, compared to 19 g/L for the original connate seawater. Dissolved chloride shows high δ 37 Cl values, ranging between +6 and +80/00 vs. SMOC. The modeled profile considers diffusive exchange between connate seawater and meteoric freshwater. Transport parameters were obtained by radial diffusion experiments. Numerical modeling was performed with the coupled reactive-transport code Hytec. Simulations suggest a diffusive-exchange time of 85±10 Ma for Cl, which correlates with a major erosional period. Simulated δ 37 Cl values between 1.002 and 1.003 agree with observed pore water δ 37 Cl. This study strongly suggests that the dissolved chloride profile in the argillites results from diffusive exchange and indicates that unfractured argillites can provide good confinement. (authors)

Argillite / cementitious materials interaction: in-situ investigations and modeling of engineered analogues from the Tournemire experimental station

International Nuclear Information System (INIS)

Techer, I.; Bartier, D.; Dauzeres, A.; Boulvais, P.

2012-01-01

Document available in extended abstract form only. Deep geological disposal of high-activity and long-period radioactive wastes is designed by the French National Agency for Radioactive Waste Management (Andra) with a confinement system based on the multiplication of argillaceous and cement-bearing barriers called 'engineered barriers'. The role of these barriers is to avoid the release of radioelements into the biosphere, as well as to prevent the potential addition of external fluids to the waste materials. In a deep clay-rich medium, cementitious materials will compose most of the building structures and will be emplaced at the immediate contact with the natural argillaceous formation. Cementitious materials are known to produce hyper-alkaline pore fluids (with pHs ranging between 10 and 13.5) during their aging. Their introduction in a deep clayey disposal is thus expected to induce a chemical disequilibrium which imprint on the safety assessment of the storage must be characterized. One way to evaluate the potential disturbing of a clayey formation at the contact to a cementitious material and thus towards the percolation of hyper-alkaline fluids consists with the investigation of natural analogues or engineered analogues. These systems deals with clayey formations that have been maintained over several years to hundred of years at the contact with a natural or engineered cementitious material. The Tournemire Experimental Platform of the French Institute for Radioprotection and Nuclear Safety (IRSN) (Aveyron, SE France) presents many contexts of so-defined engineered analogues. For instance, exploration boreholes that were drilled vertically from the tunnel basement into the Toarcian argillite in 1990/1991 were filled soon after their drilling with CEM II cement paste and concrete. Today, the over coring of such concreted boreholes gives opportunities to examine the cementitious and the clayey materials and to discuss potential changes of their intrinsic

Argillite And Crystalline Disposal Research: Accomplishments And Path-Forward.

Energy Technology Data Exchange (ETDEWEB)

McMahon, Kevin A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wang, Yifeng [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-09-01

The intention of this document is to provide a path-forward for research and development (R&D) for two host rock media-specific (argillite and crystalline) disposal research work packages within the Used Fuel Disposition Campaign (UFDC). The two work packages, Argillite Disposal R&D and Crystalline Disposal R&D, support the achievement of the overarching mission and objectives of the Department of Energy Office of Nuclear Energy Fuel Cycle Technologies Program. These two work packages cover many of the fundamental technical issues that will have multiple implications to other disposal research work packages by bridging knowledge gaps to support the development of the safety case. The path-forward begins with the assumption of target dates that are set out in the January 2013 DOE Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste (http://energy.gov/downloads/strategy-management-and-disposal-used-nuclear-fuel-and-high-levelradioactive- waste). The path-forward will be maintained as a living document and will be updated as needed in response to available funding and the progress of multiple R&D tasks in the Used Fuel Disposition Campaign and the Fuel Cycle Technologies Program. This path forward is developed based on the report of “Used Fuel Disposition Campaign Disposal Research and Development Roadmap (FCR&D-USED- 2011-000065 REV0)” (DOE, 2011). This document delineates the goals and objectives of the UFDC R&D program, needs for generic disposal concept design, and summarizes the prioritization of R&D issues.

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

International Nuclear Information System (INIS)

Urios, L.; Magot, M.; Marsal, F.; Pellegrini, D.

2010-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Urios, L.; Magot, M. [Universite de Pau et des Pays de l' Adour, IPREM UMR 5254, Equipe Environnement et Microbiologie, IBEAS, F-64013 PAU (France); Marsal, F.; Pellegrini, D. [IRSN, DSU/SSIAD/BERIS, BP 17, 92262 Fontenay aux Roses Cedex (France)

2010-07-01

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

Modeling Cl{sup -} concentration and δ{sup 37}Cl profiles in pore water across a 250 m-thick indurated argillite at the Tournemire URL (France)

Energy Technology Data Exchange (ETDEWEB)

Le Gal La Salle, Corinne; Rebeix, Romain; Lancelot, Joel [Universite de Nimes / Site GIS - 30035 Nimes cedex 01 (France); Aix-Marseille Universite, CEREGE UMR7330, 13545 Aix en Provence (France); Matray, Jean-Michel [IRSN, BP17 - 92262 Fontenay-aux-Roses Cedex (France); Bensenouci, Fethic [IRSN, BP17 - 92262 Fontenay-aux-Roses Cedex (France); IDES, UMR CNRS 8148 Universite Paris-Sud - 91405 Orsay Cedex (France); Michelot, Jean-Luc [IDES, UMR CNRS 8148 Universite Paris-Sud - 91405 Orsay Cedex (France); Dauzeres, Alexandre; Wittebroodt, Charles [IRSN, BP17 - 92262 Fontenay-aux-Roses Cedex (France); Frape, Shaun; ShouakarStash, Orphane [University of Waterloo, 200 University Avenue. West Waterloo, Ontario N2L 3G (Canada)

2013-07-01

Dissolved chloride in argillite pore water has been studied as a natural analogue for radionuclides potentially released from radioactive waste disposal. The Tournemire URL intersects impervious and compacted argillite. A previously obtained chloride concentration profile of intact rock is symmetric with a maximum concentration of 0.6±0.1 g/L, compared to 19 g/L for the original connate seawater. Dissolved chloride shows high δ{sup 37}Cl values, ranging between +6 and +80/00 vs. SMOC. The modeled profile considers diffusive exchange between connate seawater and meteoric freshwater. Transport parameters were obtained by radial diffusion experiments. Numerical modeling was performed with the coupled reactive-transport code Hytec. Simulations suggest a diffusive-exchange time of 85±10 Ma for Cl, which correlates with a major erosional period. Simulated δ{sup 37}Cl values between 1.002 and 1.003 agree with observed pore water δ{sup 37}Cl. This study strongly suggests that the dissolved chloride profile in the argillites results from diffusive exchange and indicates that unfractured argillites can provide good confinement. (authors)

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)

Berthe, G.

2012-01-01

This research is part of the studies of feasibility of CO 2 storage in deep geological strata, focusing more particularly on the evolution of the confinement properties of cap-rocks type argillite subjected to CO 2 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

Simulation of anions diffusion in Callovo-Oxfordian argillite by description of the rock microstructure

International Nuclear Information System (INIS)

Diaz, N.

2008-01-01

The Callovo-Oxfordian argillite has been proposed as host rock for deep underground radioactive wastes storage. The aim of this study is to determine the report of effective diffusion coefficients De(anion)/De(water) at the micrometer scale considering the spatial distribution of minerals in the rock. (A.L.B.)

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

International Nuclear Information System (INIS)

Diaz, N.

2009-01-01

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

Mechanical modeling of nuclear waste disposal in argillite at the Nevada Test Site

International Nuclear Information System (INIS)

Thomas, R.K.; Lappin, A.R.

1979-01-01

Numerical calculations for a near surface heater experiment in argillite conducted at the Nevada Test Site were performed using the finite element code ADINA assuming a two-dimensional axisymmetric geometry. The existence and extent of the region of tensional opening of joints surrounding the heater, predicted by the mechanical model, were confirmed by posttest borehole inspection, permeability measurements, and drillback. Exrapolation of near surface heater model to repository depths reveals the necessity for prior knowledge of the mechanical properties and state of stress in-situ. The extent of the joint opening zone, for example, is not altered by changes in the elastic modulus at the near surface, but is significantly decreased beyond certain depths depending upon the in-situ elastic modulus. Results of these calculations are presented. To further define the behavior at depth, and place bounds on the joint opening zone, far-field calculations were performed for a generic repository in argillite. Both spent fuel and high level waste heat sources were considered at different burial densities and depths. Results of a parametric study are presented in which the mechanical properties, in-situ stresses, and waste heat sources were varied

Experimental evidence for self-sealing of fractures in argillites

International Nuclear Information System (INIS)

Zhang, Chun-Liang

2010-01-01

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 m 2 . As the water was injected, the permeability dropped down by three to five orders of magnitude to 10 -15 to 10 -18 m 2 , depending on the

Equilibrium partial pressure of CO{sub 2} in the Callovo-Oxfordian argillite as a function of relative humidity

Energy Technology Data Exchange (ETDEWEB)

Lassin, Arnault [BRGM-ISTO-UMR 7327, 3av. C. Guillemin, B.P. 36009, Orleans, 45060 (France); Marty, Nicolas; Henry, Benoit; Tremosa, Joachim; Gailhanou, Helene; Gaucher, Eric C. [BRGM, 3av. C. Guillemin, B.P. 36009, Orleans, 45060 (France); Made, Benoit; Altmann, Scott [Andra, 1-7 rue Jean Monnet,Chatenay-Malabry,92298 (France)

2013-07-01

Understanding the behavior of a clay mineral-rich rock submitted to different physical-chemical perturbations is important for assessing the safety of nuclear waste disposal facilities in the corresponding geological formations. In this work we studied the effect of rock desaturation on the CO{sub 2} partial pressure signature of the Callovo-Oxfordian argillite. This integrated study, which combines experiments and geochemical modeling, points out the primary role of capillary forces on the chemical equilibria. In particular, it was possible to model, without any fitting parameters, the experimental decrease of pCO{sub 2} as a function of decreasing water content in the argillite. Moreover, this application to a complex natural system is an example of confirmation of the theoretical concepts of geochemistry in capillary contexts and is promising for dealing with other natural and industrial systems. (authors)

Rb-Sr geochronology of coarse-grained greywackes and argillites from the Coffs Harbour Block, eastern Australia

International Nuclear Information System (INIS)

Graham, I.J.; Korsch, R.J.

1985-01-01

The Coffs Harbour Block, eastern Australia, includes a sequence of turbidity-current-deposited greywackes and argillites dominated by quartz-poor to quartz-intermediate, volcanic-lithic and feldspathic types. The rocks have a common provenance consisting of dacite with minor andesite and rhyolite, derived from a continental margin volcanic arc. Rb-Sr whole-rock dating of coarse-grained greywackes and argillites suggests that low-grade regional metamorphism (prehnite-pumpellyite to lowest greenschist facies) has completely equilibrated sediments of all grain sizes, giving an age of 318 +- 8 Ma. A subsequent metamorphism which produced thermal biotite on a regional scale over the southern part of the area, re-equilibrated only the fine-grained sediments 238 +- 5 Ma ago; the coarse-grained sediments were unaffected isotopically and still lie on the older isochron. The wide variations in sandstone petrographic modes imply that the older isochron represents neither the age of volcanism in the magmatic arc nor the age of sedimentation at the deposition site, but rather dates the time of earlier metamorphism. (orig.)

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

International Nuclear Information System (INIS)

McVey, D.F.; Lappin, A.R.; Thomas, R.K.

1979-01-01

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

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

International Nuclear Information System (INIS)

Urios, Laurent; Marsal, François; Pellegrini, Delphine; Magot, Michel

2012-01-01

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 O 2 and moisture content. Aerobic bacteria were identified on the wall, in the EDZ and in the wet faulted area, whereas SO 4 -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.

On the compression behaviour of the Callovo-Oxfordian argillite

International Nuclear Information System (INIS)

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

2010-01-01

Document available in extended abstract form only. In the framework of research into radioactive waste disposal, it was decided to investigate some aspects of the volume change behaviour of the Callovo-Oxfordian argillite, a possible host rock in which the ANDRA underground laboratory of Bure (East of France) has been excavated. To do so, high pressure oedometers able to apply a maximum load of 113 MPa were used. Oedometers are widely used in Soil mechanics but not so much in Rock mechanics. In spite of applying combined stress/strain conditions (controlled vertical stress with no radial strain allowed) in which the radial stress is not controlled, their advantage is to be simple and robust to use (easy long term stress control and strain measurements). They provide a simple way to investigate the elastoplastic behaviour of soils, particularly regarding the elastic modulus, yield point and plastic compressibility. A high pressure oedometer developed at UR Navier/CERMES was used. The apparatus is a double lever arm device able to apply a maximum axial stress of 113 MPa on a specimen contained in a rigid ring of diameter 38 mm. The sample is 10 mm high. Vertical strains are monitored by using an electronic strain transducer connected to a data acquisition system. Previous calibration of the system was carried out by running a test with no sample in the ring so as to account for the effects of the compression of the top and bottom porous disks, of cell and of the piston. A reversible response of the system was observed after applying various loading cycles between 0 and 113 MPa. The specimen was trimmed by using a diamond corer of corresponding diameter and placed inside the oedometer ring. The top and bottom faces of the sample were polished by using sand paper so as to get two flat, regular and parallel faces. The ring was placed into the oedometer cell with dry porous stones and specimen was loaded under 1 MPa to ensure good contact with the porous stones and the

Hydro-mechanical coupling and transport in Meuse/Haute-Marne argillite: experimental and multi-scale approaches; Couplage hydro-me canique et transfert dans l'argilite de Meuse/Haute-Marne: approches experimentale et multi-echelle

Energy Technology Data Exchange (ETDEWEB)

Cariou, S.

2010-07-15

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)

HM modelling of in-situ gas injection tests in bentonite and argillite: the PGZ experiment

International Nuclear Information System (INIS)

Gerard, P.; Charlier, R.; Radu, J.P.; La Vaissiere, R. de; Talandier, J.; Collin, F.

2010-01-01

Document available in extended abstract form only. During long-term repository of high and intermediate level nuclear waste in deep argillaceous geological formation, steel containers will corroded and organic material will be irradiated. The two processes lead mostly to hydrogen production. This study deals with the numerical modelling of the gas migration in both the host formation and a bentonite plug, with an emphasis on coupling between the gas transfer and the mechanical strains and stresses. More particularly the study aims to support the design of the PGZ in situ experiment that will be performed by Andra in its underground laboratory at Bure. The objective of the experiment is the analysis of the dynamics of the bentonite plug re-saturation, studying the competition between the liquid water coming from the argillite and a gas injection. The modelled experiment consists of a borehole drilled in rock clay, inside which a plug of MX-80 bentonite is set. The bentonite is naturally re-saturated by water coming from the host formation. At the same time a gas pressure, higher than the initial water pressure in the host rock, is imposed at both ends of the plug. The developed model takes into account the coupling between the mechanical behaviour and the water and gas transfers in undisturbed geo-materials. It manages explicitly liquid and vapour water, gaseous and dissolved hydrogen. Elastoplastic and non-linear elastic model are used to model the behaviour of, respectively, the argillaceous rock and the bentonite. The numerical results show the small desaturation obtained in bentonite and argillite. The influence of the coupling of the mechanic on the water and gas transfers is thus limited (due to the Bishop's effective stress). The swelling of the bentonite plug is not hindered by the gas migration and the confining effect of the engineered barrier is maintained. An analysis is made of the influence of the main transfer rock properties on the gas pressure

Predicting the diagenetic evolution of argillite repositories: application of flow-through reaction cells

International Nuclear Information System (INIS)

Warr, L.; Clatter, N.; Liewig, N.

2005-01-01

In order to successfully predict the diagenetic evolution of argillite repositories we need to know i) which reactions occur under a defined set of conditions, ii) how these reactions modify the material properties of the argillite seal, and iii) 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 natural mineral reactions preserved in the geological record, in combination with results obtained from controlled laboratory experiments. Changes in the material behavior can also be reasonably assessed, as the basic physical and chemical properties of argillaceous rocks of varying mineralogy are well documented in the petrophysical and engineering literature (e.g. Bell, 1999). Probably the most difficult task, however, is to assess the rates of the chemical reactions involved. This difficulty reflects our poor knowledge of the reaction kinetics for these low-temperature, fine-grained mineral materials, and apparent differences between rates estimated from natural and experimental systems. A new approach to monitoring the reaction kinetics of fine-grained minerals in percolating solution has been developed using flow-through reaction (wet-cell) chambers. These devices can be routinely mounted onto the X-ray diffractometer for in-situ measurements of the sample. With the aid of a cap to maintain constant volume, the device can be subjected to diagenetic or hydrothermal conditions (<150 C). First results are here presented for the alteration of Callovo-Oxfordian shales in a reactive simple young fluid (strongly alkaline, pH ca. 13) at 90 C, designed to simulate the alteration of concrete at the repository site. (authors)

Hydro-mechanical behaviour of crushed COx argillite used as backfilling material in HLW repository

International Nuclear Information System (INIS)

Tang Chaosheng; Shi Bin; Cui Yujun; Anh-Minh Tang

2010-01-01

At present, the crushed Callovo-Oxfordian (COx) argillite powder is proposed as an alternative backfilling material in France, which will be constructed in the engineering barrier of high-level radioactive waste (HLW) repository. In this investigation, the compression behavior of two crushed COx argillite powders (coarser one and finer one) was studied by running l-D compression tests with several loading-unloading cycles. After the final dry density 2.0 g/cm 3 was reached, the specimen was flooding with distilled water and the evolution of axial stress was studied during saturation process. The effects of initial axial stress level and grain size distribution (GSD) on hydro-mechanical behaviour of compacted specimen were analyzed. The results show that the compression curves are significantly influenced by the GSD of the soils. To obtain the same degree of compaction, the axial stress applied to finer soil is much higher than that of coarser soil. In addition, the compression index of the finer soil is bigger than that of coarser soil. The swelling index at initial water content increases with the dry density and seems to be independent of the GSD. During saturation, the initial lower axial stress causes obvious swelling behavior for both the coarser and finer powder samples and the corresponding axial stress increase gradually. At initial higher axial stress condition, monotone collapse behavior is observed for the coarser powder samples. Whereas the axial stress decrease firstly, then increase and finally decrease again for the finer powder samples. After saturation, the equilibrium axial stresses of finer powder samples are higher than that of coarser powder samples. (authors)

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)

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

International Nuclear Information System (INIS)

Chautard, Camille; Dauzeres, Alexandre; Maillet, Anais

2014-01-01

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

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)

Evolution of the argillite / CEM I interface at 70 C.: in situ tests and modelling results

International Nuclear Information System (INIS)

Lalan, P.; Dauzeres, A.; Barker, E.; De Windt, L.; Detilleux, V.; Desveaux, P.

2015-01-01

French radioactive waste disposal concept involves cementitious materials in a clayey host-rock. The presence of exothermic wastes in the storage cells may induce a temperature of about 70 Celsius degrees at the material interfaces. At present, experiment thermal conditions have been undertaken at about 20 C. degrees and studies at higher temperature are really scarce, especially experiments considering diffusion through the cement / clay interface. The still on-going study presented here is focusing on argillite / CEM-I interface. A one-year experiment under in situ conditions at the Tournemire experimental station (IRSN) was carried out and meanwhile, preliminary reactive transport modelling with HYTEC helped to understand the impact of a high temperature on the physico-chemical behaviour of cement / clay interface. The first results showed decalcification of cement and diffuse carbonation as well as a possible illite precipitation of clay-type phases. A C-S-H ribbon appeared at the interface between the two materials and a layer grew between the C-S-H ribbon and the cementitious material. This layer contained zeolites and behaved as a diffusive barrier. After one year of in situ interactions, the disturbance thickness was about 350 microns in CEM-I cement paste and about 100 microns in argillite. The modelling reproduced relatively well the experimentally observed processes but the extension of the disturbance is too wide and the zeolite layer is misplaced according to the experimental observations. This study highlights the lack of data at highest temperature on the reaction kinetics, diffusion coefficients but also on porosity variations. (authors)

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

International Nuclear Information System (INIS)

Hu, Dawei; Zhang, Fan; Xie, Shouyi; Shao, Jianfu

2012-01-01

Document available in extended abstract form only. Due to its low permeability (10 -18 to 10 -20 m 2 ), 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

Experimental study of the anisotropic properties of argillite under moisture and mechanical loads

International Nuclear Information System (INIS)

Yang, D.S.; Chanchole, S.; Wang, L.L.; Bornert, M.; Gatmiri, B.

2012-01-01

Document available in extended abstract form only. Due to various factors, such as sedimentation, layered morphology of clay mineral, in-situ stress, etc., the behavior of argillite rocks is often anisotropic. In order to study the anisotropy of the Callovo-Oxfordian (COx) argillite considered as a possible host rock for high-level radioactive nuclear waste repository in France, a series of tests including uniaxial compression and dehydration and hydration at different constant applied stress levels, are carried out using a specific setup combining mechanical and moisture loading devices. During these hydro-mechanical tests, this specific setup can also continuously capture images of the sample surfaces to be subsequently analyzed using Digital Image Correlation techniques (DIC) in order to determine full-field strains. In this study, three sampling directions are used with the angle θ between the bedding plane and the cylindrical sample axis equal to 45 deg., 60 deg. and 90 deg.. To investigate the mechanical anisotropy, uniaxial compressive tests with mechanical loading and unloading cycles are performed on several different samples at the same moisture level. The results show that the mechanical parameters (apparent modulus, failure stress) depend on loading orientation relative to the stratification plane. For a given water content, the failure stress reaches maximum values for θ =90 deg. and minimum values for θ =45 deg.. To study the hydric anisotropy, dehydration and hydration tests under stress-free conditions are performed on two cylindrical samples (θ=90 deg. and θ=60 deg.). Three cycles of hydration and dehydration are carried out by varying the relative humidity between 40% and 95%. The sample weight, the deformation measured by strain gages and the relative humidity are continuously recorded during the test by means of another specific setup described in [Pham et al., 2007]. Fig.1a illustrates the evolution of the strains of the sample EST28030-No

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

International Nuclear Information System (INIS)

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

2010-01-01

by scanning electron microscope observations to identify the related mineral alterations. Significant changes were observed in the mineral compositions of the whole rocks and in the chemical and Sr-isotopic composition of the leachates when the storage duration in ambient temperature or during heating increased. The main variations were: (1) a significant decrease of the element contents in the leachates, meaning in turn the decrease of the released elements from minerals constitutive of the rocks when duration increased. This decrease was rapid in the COX argillite, after storage at ambient temperature and exposition at 95 deg. C, and was followed by a progressive trend to a new stable state. In the Opalinus Clays, the decrease was progressive and accompanied by a decrease of the 87 Sr/ 86 Sr ratio of the leachates, but no trend towards a new stable state could be observed; (2) an alteration of pyrite followed by a precipitation of Ca-sulfate, which appeared to start in the core of the crystals towards the rims; it also lead to the replacement of Fe-sulfides by Fe-oxides; (3) a probable precipitation of new mineral phases in the rocks, such as Fe-oxy-hydroxides and/or jarosite that could not be visualized by electron microscopic observation because of their very limited amount and very small grain size. All the modifications call for an oxidation of pyrite probably combined with dehydration of the rock, inducing changes in the pH conditions of interstitial fluids. They probably also induced an oxidation of the organic matter, which was enhanced by temperature increase. The study allowed identification of the changes occurring in the rocks exposed to atmosphere that are recorded in the mineralogical feature and in the chemical and Sr isotopic composition of their soluble mineral phases. Leaching appears to be an appropriate procedure for identifying and quantifying such reactions that are explained by oxidation and dehydration processes of the mineral and organic

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)

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)

Geological repository layout for radioactive high level long lived waste in argillite

International Nuclear Information System (INIS)

Gaussen, JL

2006-01-01

In the framework of the 1991 French radioactive waste act, ANDRA has studied the feasibility of a geological repository in the argillite layer of the Bure site for high level long lived waste. This presentation is focussed on the underground facilities which constitute the specific component of this project. The preliminary underground layout which has been elaborated is based on four categories of data: - the waste characteristics and inventory; - the geological properties of the host argillite; - the long term performance objectives of the repository; - the specifications in terms of operation and reversibility. The underground facilities consist of two types of works: the access works (shafts and drifts) and the disposal cells. The function of the access works is to permit the implementation of two concurrent activities: the nuclear operations (transfer and emplacement of the disposal packages into the disposal cells) and the construction of the next disposal cells. The design of the drifts network which matches up to this function is also influenced by two other specifications: the minimization of the drift dimensions in order to limit their influence on the integrity of the geological formation and the necessity of a safe ventilation in case of fire. The resulting layout is a network of 4 parallel drifts (2 of them being dedicated to the operation, the other two being dedicated to the construction activities). The average diameter of these access drifts is 7 meters. The link between the surface and the underground is ensured by 4 shafts. The most important function of the disposal cells is to contribute to the long term performance of the repository. In this regard, the thermal and geotechnical considerations play an important role. The B wastes (intermediate level wastes) are not (or not very) exothermic. Consequently, the design of their disposal cells result mainly from geotechnical considerations. The disposal packages (made of concrete) are piled up in

Interpreting strain measurements when drilling anisotropic rocks: return of experience from using CSIRO cells in Tournemire argillite

International Nuclear Information System (INIS)

Ben Ouanas, Abdelmonem

2010-01-01

In Geomechanics, determining the state of stress and the rheology of rock massif can be obtained by measuring the strain response of the ground under the effect of a known stress. A method among others is to use a cell integrated (with strain gauges oriented in different directions) installed in a borehole and secured to the mass through an epoxy glue. This measurement is used, notably, to determine the stress state in situ by the 'overcoring' method and the elastic parameters of the rock from the 'biaxial' test. Between November 2005 and January 2006, a geomechanical testing campaign was conducted in the argillaceous formation of the Tournemire experimental site (Aveyron, France) using CSIRO Hi cells. The strain measurements obtained during overcoring and biaxial tests have shown unusual phenomena, which have made difficult the determination of anisotropic elastic parameters of the rock and the access to the site stress. Therefore, through researches for explanations of the origin of these phenomena, this thesis aimed to improve and contribute to the understanding of the Tournemire argillite behaviour and to upgrade the measurement protocol as well as the interpretation of cells CSIRO's strain. The approach was, firstly, to issue a number of hypotheses to explain certain phenomena observed in literature. In a second step, these hypotheses were tested through analytical and numerical modelling of the biaxial and overcoring tests then through the realization of new experiments in situ within laboratory on argillite, and also on materials tests (cement, sample of glue). It is concluded that the unusual phenomena observed are essentially the result of the conditions for implementing in situ CSIRO's cell. The study particularly focused on the artefacts induced by the visco-plastic behaviour of the epoxy glue when it is incompletely polymerised. The role of damage on the rock generated by drilling operations is also discussed. Some practical recommendations for

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

International Nuclear Information System (INIS)

Poulain, S.

2006-12-01

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

Thermal Analysis of a Nuclear Waste Repository in Argillite Host Rock

Science.gov (United States)

Hadgu, T.; Gomez, S. P.; Matteo, E. N.

2017-12-01

Disposal of high-level nuclear waste in a geological repository requires analysis of heat distribution as a result of decay heat. Such an analysis supports design of repository layout to define repository footprint as well as provide information of importance to overall design. The analysis is also used in the study of potential migration of radionuclides to the accessible environment. In this study, thermal analysis for high-level waste and spent nuclear fuel in a generic repository in argillite host rock is presented. The thermal analysis utilized both semi-analytical and numerical modeling in the near field of a repository. The semi-analytical method looks at heat transport by conduction in the repository and surroundings. The results of the simulation method are temperature histories at selected radial distances from the waste package. A 3-D thermal-hydrologic numerical model was also conducted to study fluid and heat distribution in the near field. The thermal analysis assumed a generic geological repository at 500 m depth. For the semi-analytical method, a backfilled closed repository was assumed with basic design and material properties. For the thermal-hydrologic numerical method, a repository layout with disposal in horizontal boreholes was assumed. The 3-D modeling domain covers a limited portion of the repository footprint to enable a detailed thermal analysis. A highly refined unstructured mesh was used with increased discretization near heat sources and at intersections of different materials. All simulations considered different parameter values for properties of components of the engineered barrier system (i.e. buffer, disturbed rock zone and the host rock), and different surface storage times. Results of the different modeling cases are presented and include temperature and fluid flow profiles in the near field at different simulation times. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and

Small scale heater tests in argillite of the Eleana Formation at the Nevada Test Site

International Nuclear Information System (INIS)

McVey, D.F.; Thomas, R.K.; Lappin, A.R.

1979-11-01

Near-surface heater tests were run in the Eleana Formation at the Nevada Test Site, in an effort to evaluate argillaceous rock for nuclear waste storage. The main test, which employed a full-scale heater with a thermal output approximating commercial borosilicate waste, was designed to operate for several months. Two smaller, scaled tests were run prior to the full-scale test. This report develops the thermal scaling laws, describes the pretest thermal and thermomechanical analysis conducted for these two tests, and discusses the material properties data used in the analyses. In the first test, scaled to a large heater of 3.5 kW power, computed heater temperatures were within 7% of measured values for the entire 96-hour test run. The second test, scaled to a large heater having 5.0 kW power, experienced periodic water in-flow onto the heater, which tended to damp the temperature. For the second test, the computed temperatures were within 7% of measured for the first 20 hours. After this time, the water effect became significant and the measured temperatures were 15 to 20% below those predicted. On the second test, rock surface spallation was noted in the bore hole above the heater, as predicted. The scaled tests indicated that in-situ argillite would not undergo major thermostructural failure during the follow-on, 3.5 kW, full-scale test. 24 figures, 6 tables

Gas and water flow in the Callovo-Oxfordian argillite

International Nuclear Information System (INIS)

Harrington, J.F.; Noy, D.J.; Talandier, J.

2010-01-01

Document available in extended abstract form only. Understanding the impact and fate of this gas phase is of significant importance within performance assessment and for the accurate long-term prediction of repository evolution. This paper describes the initial results from an ongoing experimental study to measure the two-phase flow behaviour of the Callovo-Oxfordian argillite from the Bure underground research laboratory (URL) in France, using the custom-designed BGS permeameter. The primary objectives of the study are to measure: (i) the hydraulic conductivity and intrinsic permeability; (ii) the capillary displacement pressure; (iii) the effective gas permeability and relative permeability to gas for a range of conditions; and (iv) the post-test gas saturation. During testing, the specimen, a cylinder of 54 mm thickness, cut perpendicular to bedding, is subject to an isotropic confining stress, with fluids injected through the base of the specimen. A novel feature of the apparatus is the use of porous annular guard-ring filters around the inflow and outflow filters. The pressures in these two 'guard-rings' can be independently monitored to provide data on the distribution of pressure and anisotropy of the sample. Initial measurements, performed on a specimen orientation perpendicular to the bedding plane, have been divided into three components: re-saturation and consolidation; hydraulic properties; gas behaviour. During the initial period of equilibration, re-saturation of the sample were noted. Net volume change due to re-saturation closely agreed with pre-test geotechnical measurements of water saturation, suggesting the bulk of the gas phase was resident in non-dilatant pores and that the specimen was fully saturated at the onset of testing. A two step consolidation test was then performed with confining pressure raised to 11 MPa for 5 days and then to 12.5 MPa for a further 8 days. Values for drained bulk modulus based on the total volume of fluid

Characterization of the failure in Callovo-Oxfordian argillite under plane strain compression using full field measurements

International Nuclear Information System (INIS)

Besuelle, P.

2012-01-01

orthogonal to the plane strain direction, is in contact with a hard transparent window. The deformation of this surface is representative of the deformation in the whole specimen, up to and beyond strain localization. Therefore the evolution of the strain field in the sample can be measured by digital image correlation (DIC) of photographs taken of this surface. It is noted that the cell can sustain a confining pressure up to 100 MPa and so the regime of deformation in soft rocks from brittle through to ductile can be studied. Moreover, the stress path that is imposed to the specimen is not an axisymmetric state and is more realistic with respect to the paths followed in the field. In the selected results, we analysed the process of failure in the Callovo-Oxfordian argillite. First, strain localization under the form of shear bands propagate through the specimen, and then cracks born and propagate in the middle of the band. Complex patterns of cracks, with sets of conjugated cracks are observed in some case. The effect of the mean stress applied during tests on the failure is also observed. The kinetic of crack propagation is studied quantitatively, using the displacement field measured by DIC. The displacement gap on cracks is decomposed in a sliding component and a opening. The mechanical response of argillite specimens is also presented, with the link between post peak response (stress softening) and localization. (authors)

Long term behaviour of glass and steel in interaction with argillites in deep geological conditions

International Nuclear Information System (INIS)

Bildstein, O.; Lartigue, J.E.; Devallois, V.; Pointeau, V.; Trotignon, L.; Michau, N.; Cochepin, B.; Munier, I.

2010-01-01

. C) was conducted in order to identify the parameters controlling the overall reactivity of the system. This sensitivity analysis included kinetic parameters for selected minerals, diffusion coefficient, corrosion rate, and gas partial pressure. Another set of calculations was also performed in non-isothermal conditions using the variable temperature field resulting from the heat produced by the waste packages. Modeling results in the reference case show that the glass alteration products mainly consist of zeolites (gyrolite, natrolite) and pure silica minerals (chalcedony). Steel corrosion products are distributed as follows: iron oxides (magnetite or goethite) at the core of the canister; iron silicates (cronstedtite), aluminosilicates (chamosite, Fe-saponite), and sulphide (pyrrhotite) precipitate at the interface between glass and argillites. In the argillites, primary minerals such as dolomite, smectites and calcite are destabilized close to the canister surface. These minerals disappear in favour of gyrolite, natrolite, chalcedony and philippsite-K. The sensitivity analysis shows that the relative amount and evolution in space and time of these secondary minerals strongly depend on the corrosion rate and the release of gas (H 2 and possibly CH 4 ) in the system. The relative intensity of the transport process (diffusion coefficient) and mineral reaction rates (kinetic rate and reactive surface area) also strongly influence the evolution of the system (nature of secondary phases, porosity, gas pressure...). These reaction pathways and para-genesis predicted by the calculations are qualitatively supported by 'short-term' (∼1 year) experiments. A significant reduction of porosity is systematically predicted at the interface between the different materials and is also locally observed in the different materials depending on the simulation conditions, e.g. depending on the corrosion rate. An overall decrease of the reactivity of the system is also

Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock: FY17 Progress. Predecisional Draft

Energy Technology Data Exchange (ETDEWEB)

Zheng, Liange; Rutqvist, Jonny; Xu, Hao; Kim, Kunwhi; Voltolini, Marco; Cao, Xiaoyuan

2017-07-03

The focus of research within the Spent Fuel and Waste Science and Technology (SFWST) (formerly called Used Fuel Disposal) Campaign is on repository-induced interactions that may affect the key safety characteristics of EBS bentonite and an argillaceous rock. These include thermal-hydrologicalmechanical- 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 materials and petrophysical characteristics, particularly the impacts of temperature rise caused by waste heat. This report documents the following research activities. Section 2 presents THM model developments and validation, including modeling of underground heater experiments at Mont Terri and Bure underground research laboratories (URLs). The heater experiments modeled are the Mont Terri FE (Full-scale Emplacement) Experiment, conducted as part of the Mont Terri Project, and the TED in heater test conducted in Callovo-Oxfordian claystone (COx) at the Meuse/Haute-Marne (MHM) underground research laboratory in France. The modeling of the TED heater test is one of the Tasks of the DEvelopment of COupled Models and their VAlidation against EXperiments (DECOVALEX)-2019 project. Section 3 presents the development and application of thermal-hydrological-mechanical-chemical (THMC) modeling to evaluate EBS bentonite and argillite rock responses under different temperatures (100 °C and 200 °C). Model results are presented to help to understand the impact of high temperatures on the properties and behavior of bentonite and argillite rock. Eventually the process model will support a robust GDSA model for repository performance assessments. Section 4 presents coupled THMC modeling for an in situ test conducted at Grimsel underground laboratory in Switzerland in the Full

Geology of the Syncline Ridge area related to nuclear waste disposal, Nevada Test Site, Nye County, Nevada

International Nuclear Information System (INIS)

Hoover, D.L.; Morrison, J.N.

1980-01-01

The Syncline Ridge area is in the western part of Yucca Flat, Nye Co., Nev. Drill holes, geophysical surveys, mapping, and laboratory studies during 1976 through 1978 were used to investigate argillite in unit J (Mississippian) of the Eleana Formation (Devonian and Mississippian) as a possible nuclear waste repository site. Argillite in unit J has a minimum stratigraphic thickness of at least 700 m. The argillite underlies most of the Syncline Ridge area east of the Eleana Range, and is overlain by Quaternary alluvium and the Tippipah Limestone of Syncline Ridge. At the edges of the Syncline Ridge area, alluvium and volcanic rocks overlie the argillite. The argillite is underlain by more than 1000 m of quartzite, siliceous argillite, and minor limestone in older units of the Eleana Formation. These older units crop out in the Eleana Range. The area is divided into southern, central, and northern structural blocks by two lateral faults. The southern and central blocks either have volumes of argillite too small for a repository site, or have irregular-shaped volumes caused by Mesozoic high-angle faults that make the structure too complex for a repository site. The northern block appears to contain thick argillite within an area of 6 to 8 km 2 . The postvolcanic history of the Syncline Ridge area indicates that the area has undergone less deformation than other areas in Yucca Flat. Most of the late Tertiary and Quaternary deformation consisted of uplift and eastward tilting in the Syncline Ridge area. Preliminary engineering geology investigations indicate that although the competency of the argillite is low, the argillite may be feasible for construction of a nuclear waste disposal facility. Physical, thermal, chemical, and mineralogical properties of the argillite appear to be within acceptable limits for a nuclear waste repository

Quality evaluation of carbonaceous industrial by-products and its effect on properties of autoclave aerated concrete

Science.gov (United States)

Fomina, E. V.; Lesovik, V. S.; Fomin, A. E.; Kozhukhova, N. I.; Lebedev, M. S.

2018-03-01

Argillite is a carbonaceous industrial by-product that is a potential source in environmentally friendly and source-saving construction industry. In this research, chemical and mineral composition as well as particle size distribution of argillite were studied and used to develop autoclave aerated concrete as partial substitute of quartz sand. Effect of the argillite as a mineral admixture in autoclave aerated concrete was investigated in terms of compressive and tensile strength, density, heat conductivity etc. The obtained results demonstrated an efficiency of argillite as an energy-saving material in autoclave construction composites.

Experimental formation of cronstedtite from Cox argillite-iron interaction at decreasing temperature in the 90 deg. C-40 deg. C range

International Nuclear Information System (INIS)

Pignatelli, Isabella; Mosser-Ruck, Regine; Rozsypal, Christophe; Truche, Laurent; Randi, Aurelien; Bartier, Daniele; Cathelineau, Michel; Ghanbaja, Jaafar; Mouton, Ludovic; Michau, Nicolas

2012-01-01

Document available in extended abstract form only. Cronstedtite crystals experimentally formed during a cooling experiment (90 deg.C-40 deg. C) simulating the time-temperature evolution of the iron-clay system around the steel overpacks in nuclear waste disposal, were characterized by XRD, SEM and TEM study. Cronstedtite is a T-O phyllosilicate with general formula (Fe 2+ 3-x Fe 3+ x )(Si 2-x Fe 3+ x )O 5 (OH) 4 , with 0 2 ), Callovo-Oxfordian argillite (COx) of the Paris Basin (with a solution/COx mass ratio of 10) and metal iron (powder and plates, with an iron powder/COx mass ratio of 0.5). This system was put in Teflon-line autoclaves heated at (90±2) deg. C for 6 months; then the temperature was decreased every month by step of 10 deg. C until 40 deg. C. The XRD results on run products clearly show that the T-O phyllosilicates crystallize and replace the predominant clay in the starting argillite, e.g. illite-smectite mixed-layer clays when the experimental temperature decreases. The reflections at 7.1 Angstrom, 4.76 Angstrom, 3.55 Angstrom and 2.73 Angstrom indicate that the T-O phyllosilicate formed is cronstedtite, but this technique is not efficient to determine its polytype. The SEM analyses confirm the presence of cronstedtite and show the morphological evolution of crystals with the temperature. At 90 deg. C three morphologies are recognized: trigonal pyramids and cones with hexagonal or rounded cross-section (Fig. 1), these crystals coexist with hairy berthierine-like minerals, as described by [10] and [12] The three cronstedtite shapes are observed until 70 deg. C and at lower temperatures the pyramidal morphology is dominant. From the energy dispersive X-ray analyses, structural formula of cronstedtite were calculated. The Fe II / Fe III ratio was adjusted to fix the octahedron to 3 in the calculation of the structural formula. Slight differences in the chemical compositions of cronstedtites are noticed: the pyramidal crystals have more Fe 2+ in the

Petrophysical characterization of Callovo-Oxfordian argillites from the deep borehole Andra EST433 of Montiers-Sur-Saulx (Meuse, France)

International Nuclear Information System (INIS)

Cosenza, P.; Pret, D.; Camerlynck, C.; Fleury, M.; Geraud, Y.; Kremer, T.; Zamora, M.; Landrein, P.; Lebon, P.; Villieras, F.

2012-01-01

Document available in extended abstract form only. Petro-fabric and physico-chemical properties of Meuse/Haute-Marne Callovo-Oxfordian argillite have been extensively studied (e.g. Trouiller, 2006). This research project is aiming at establishing micro-macro models to link microstructural patterns and macroscopic measurements. In this context, data are acquired on the same samples at different scales: (a) microscopic scale (identification of mineralogical phases, mineral mapping, surface area, pore size distribution) and (b) macroscopic scale (hydraulic conductivity, elastic wave velocities, resistivity, thermal conductivity). Ultimately the resulting micro-macro models would be used by Andra to construct 3D representation of the petrophysical properties within the Callovo-Oxfordian formation by the mean of logging data. This project is part of the research programme TAPSS2000 (Present and past transfers in a sedimentary aquifer - aquitard system: a 2000 meter deep drill-hole in the Mesozoic of the Paris Basin). Data acquisition is performed on 9 cores (taken from 558.5 m to 619.5 m deep) of the deep borehole ANDRA EST433 located at Moultiers-sur-Saulx (Meuse, France). These data on the microstructure and the macroscopic physical behaviour of Callovo-Oxfordian show the following features: - The higher the P-and S- wave velocities, the higher the radiologic density measured by X-Ray tomography. These high values of velocities and density are associated with carbonates, the most rigid phase among the rock-bearing minerals. P-wave velocity measurements do not exhibit significant scale effect (i.e., logging vs laboratory). - The most heterogeneous samples (with regard to their values of elastic wave velocities and radiologic density) are located in the upper part of the Callovo-Oxfordian formation, where argillite is more carbonated. On the contrary, the most homogeneous cores that exhibit lower values of elastic wave velocities are located at deeper depths: they are

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)

Development of a viscoplastic constitutive model for deep rocks: concepts And application to the MHM argillite

International Nuclear Information System (INIS)

Silvestre, Alexandra; Laigle, Francois

2012-01-01

cancellation of volumetric strains rate, in particular of dilation for high shear strains, - An ultimate friction angle related to the critical state angle, - Volumetric strains contractant or dilatant, depending on the state of stress. The delayed behaviour is implemented by the definition of a long term strength threshold, and allows taking into account: - The effect of the excavation average rate, - The effect of a stopping in excavation works, - The long-term behavior of an unsupported face heading. This advanced constitutive model is described in the paper from a conceptual point of view. The aim is not to define theoretical equations but only to expose the main physical concepts implemented. To illustrate the relevance of the model, an application to the Meuse/Haute-Marne Argillite is given from a simple example. (authors)

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)

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

International Nuclear Information System (INIS)

M'Jahad, S.

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 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)

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

International Nuclear Information System (INIS)

Savoye, Sebastien

2008-01-01

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.)

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 (biofilms are within the interface zones. A major restriction for the initial development of microbial colonies is the high pH controlled by the cement solution. Archea are able to survive

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

International Nuclear Information System (INIS)

Chautard, C.

2013-01-01

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

M4SF-17LL010301071: Thermodynamic Database Development

Energy Technology Data Exchange (ETDEWEB)

Zavarin, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Institute, Physical & Life Sciences; Wolery, T. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Akima Infrastructure Services, LLC

2017-09-05

This progress report (Level 4 Milestone Number M4SF-17LL010301071) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Argillite Disposal R&D Work Package Number M4SF-17LL01030107. The DR Argillite Disposal R&D control account is focused on the evaluation of important processes in the analysis of disposal design concepts and related materials for nuclear fuel disposal in clay-bearing repository media. The objectives of this work package are to develop model tools for evaluating impacts of THMC process on long-term disposal of spent fuel in argillite rocks, and to establish the scientific basis for high thermal limits. This work is contributing to the GDSA model activities to identify gaps, develop process models, provide parameter feeds and support requirements providing the capability for a robust repository performance assessment model by 2020.

FRACTEX: an experiment aiming at characterizing the transport properties of a secondary fault

International Nuclear Information System (INIS)

Wittebroodt, C.; Matray, J.M.; Dick, P.; Cabrera, J.; Barnichon, J.D.

2012-01-01

Document available in extended abstract form only. Because of their favourable transport and retention properties, argillaceous rocks are considered as potential host rocks for radioactive waste repositories. At the request of the French Authority of Nuclear Safety (ASN), the French Institute for Radioprotection and Nuclear Safety (IRSN) is in charge of an independent expertise of the French industrial (Andra's) project. Therefore, IRSN develops experimental research programs in such geological formations at the Tournemire Underground Research Laboratory (URL, Aveyron, France). One of the objectives of this project is to evaluate the occurrence and the driving processes controlling the radionuclide migration through an argillaceous formation similar to those studied elsewhere for nuclear waste disposal. Since undisturbed argillaceous rocks display very low values for both hydraulic conductivity (K h ) and water content (θ e ), diffusion is considered to be the main transport mechanism governing radionuclide migration through the argillite. On the other hand, in the presence of fracture in the argillaceous formation, the flux of water through this preferential pathway could dramatically accelerate the migration of the radionuclide it contains. Thus, the implementation of a radwaste disposal facility requires a precise sedimentary and structural characterization of the preselected site to guarantee the presence of a regular, homogenous and fault-free clay layer over a large area and so to determine its ability to ensure an effective radionuclide confinement. The site characterization and fracture detection can be performed using complementary approaches such as geological studies, in situ measurements and non-destructive geophysical methods. In order to evaluate both the capacity and the limit of these seismic methods to detect a secondary fault in an argillaceous media, IRSN performed a 3D HR seismic survey from the surface of its Tournemire URL. Due to the weak

Influence of antioxidants synthesized by plants on physico-chemical and microbiological evolution of Callovo-Oxfordian clay material

International Nuclear Information System (INIS)

Ubersfeld, Dimitri

2016-01-01

This study is a part of the deep disposal site development for radioactive waste in Meuse-Haute Marne (France), most specifically on the bio-physico-chemical conversion of sedimentary clay rocks (Callovo- Oxfordian, COx), excavated and stored on surface in the form of heap. During the experimental and operational phases, several million cubic meters of argillite will be excavated. Argillite stored in the open air will be exposed to meteoritic alterations, oxidizing conditions of surface and colonized biologically (plants, bacteria, fungi). The aim of the thesis is to study the impact of naturally derived antioxidants from revegetation of heap with antioxidant-producing plants on the physical, chemical or microbial weathering processes of argillite. This work was designed to (i) identify suitable naturally derived antioxidants and the plants to produce them (ii) assess the antioxidant inhibitory effects on weathering and leaching COx metals in the laboratory, (iv) field test selected plants on the heap, (iii) follow in situ physicochemical and microbiological evolution of the argillite heap planted with antioxidant producing plants. In the laboratory, percolating model antioxidants of Lamiaceae (linalool, thymol, carvacrol) through a packed column of argillite showed variable water weathering/leaching rate depending on the metal elements present; very low for aluminum (<1 o/oo), between 1-3% for other metals (Ca, Mg, Fe...) and reach more than 60% for sodium. With thymol at 20 mg/l for 3 months, it was found that there are a decrease in sulfur leached amount and the metal elements from the sulfides (Fe, As) and carbonates (Ca, Sr) and inhibition of bacterial and fungal microflora growths. However, intake of artificial root exudates in columns stimulates microbial growth, improves the availability of aluminum, iron and provides sequestration of calcium. Among the tested plants, lavender and lavandin were selected. Two successive plantation tests were carried out in

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

International Nuclear Information System (INIS)

Dauzeres, A.

2010-09-01

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)

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

International Nuclear Information System (INIS)

Charpentier, D.; Cathelineau, M.; Mosser-Ruck, R.; Bruno, G.

2001-01-01

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)

PHREEQC integrated modelling of plutonium migration from alpha ILL radwaste: organic complexes, concrete degradation and alkaline plume

International Nuclear Information System (INIS)

Cochepin, B.; Munier, I.; Giffaut, E.; Grive, M.

2010-01-01

Document available in extended abstract form only. The effects of organic compounds derived from Long-Lived Intermediate-Level waste (LLILW) degradation need to be precisely described regarding the radionuclide migration in storage cells and argillites. These evaluations play a major role in the final decision for accepting these waste products in the future storage facility. The evaluation process engaged by Andra implies the use of coupled chemical transport tools able to take into account the linking of processes occurring in storage conditions as well as the different cell components (containers, packages, lining...). The relevance of this approach must fundamentally be based on a consistent characterization concerning (i) the waste packages, (ii) their degradation products (nature and kinetics), (iii) the chemical evolution of these products in the storage disposal (for cement material particularly) and in the argillites, and (iv) the correlation with the radionuclide behavior regarding to these sequestering agents (chemistry and transport). Andra is now involved in an internal evaluation of technological organic waste packages contaminated by plutonium coming from the MOX fuel plant called MELOX located at Marcoule (France), considering the consistent work undertaken to characterize these organic agents. This evaluation is based on an integrated representation in terms of chemical processes and transport of the concrete chemical degradation (e.g. waste packages, backfill and lining), the alkaline plume in the near field of argillites and the plutonium-organic complexes. The conceptual model is based on the following assessments: On the chemical aspect: (i) Both concrete and argillites undertake chemical perturbations with dissolution/precipitation, ion exchanges, surface and aqueous complexation. (ii) The degradation products of the MELOX waste organic compounds are limited to five major organic acids: iso-saccharinic (ISA), acetic, phtalic, adipic and

DECOVALEX-THMC Project. Task C. Hydro-mechanical response of the Tournemire argillite to the underground openings excavation: unsaturated zones and mine-by-test experiment. Final Report

Energy Technology Data Exchange (ETDEWEB)

Rejeb, A.; Rouabhi, A. (Ecole des Mines de Paris (France)); Millard, A. (Commissariat d' Energie Atomique (France)); Massmann, J. (Hannover Univ. (DE)); Uehara, S. (Kyoto Univ. (Japan))

2008-06-15

This report describes the final results of Task C of the international DECOVALEX-THMC project devoted to Excavation Damaged Zone (EDZ) in argillaceous rock at the Tounemire site in France. Task C is aimed to develop adequate numerical models for interpretation of observed damaged zones around three openings excavated at different times. The research teams are asked to model the evolution of the EDZ with time and to compare their results with measurements that were performed at the site. The main objective is to investigate the hydro-mechanical behavior of Tounemire argillite around the three openings (1881 tunnel, 1996 gallery, 2003 gallery) of Tournemire site. The work was divided into 3 parts: 1. Modelling of the unsaturated zones around the three openings; 2. Modelling of the mine-by-test experiment around the 2003 gallery; 3. EDZ modeling around the 3 openings. Each research team has performed its own HM numerical calculations based on the principal following considerations: The hydraulic time dependent boundary condition at each opening wall was calculated by the Kelvin equation using the provided humidities and temperatures; The effective stress approach of partially saturated medium was used; The swelling-shrinkage of Tournemire argillite was taken into account; The capillary pressure curve was assumed to be given by the Van Genuchten relation and calibrated from the provided data of the two successful laboratory tests; The influence of the degree of saturation on liquid water permeability was modelled using a relative permeability function which is based also on the Van Genuchten model; The intrinsic permeability was calibrated in order to get a better fit with experimental data. To achieve the first objective, the three research teams act as follows: 2D HM coupled simulations have been undertaken by ISEB-BGR team. Hydraulic and mechanical anisotropies were considered; 2D HM coupled simulations have been also undertaken by CEA-IRSN team. Only mechanical

Preliminary appraisal of gravity and magnetic data at Syncline Ridge, Western Yucca Flat, Nevada Test Site, Nye County, Nevada

International Nuclear Information System (INIS)

Ponce, D.A.; Hanna, W.F.

1982-01-01

A gravity and magnetic study of the Syncline Ridge area was conducted as part of an investigation of argillite rocks of the Eleana Formation under consideration as a medium for the possible storage of high-level radioactive waste. Bouguer gravity anomaly, low-level aeromagnetic anomaly, density, and magnetization data collectively indicate the following, relative to the Eleana Formation, the principal target of the investigation: (1) in an area extending northwestward from Mine Mountain, through Syncline Ridge, to the Eleana Range, the Eleana Formation, where not exposed, occurs at depths of less than approx. 200 m, except for a small region of exposed older Paleozoic rocks; (2) in the region of shallowly buried Eleana Formation, occurrences of volcanic rock cover are delineated by low-level aeromagnetic anomaly data, which also discriminate normally polarized from reversely polarized tuff units; and (3) selective detection of high-quartz argillite relative to low-quartz argillite using surface gravity data is not feasible if the high-quartz and low-quartz varieties are intimately interbedded, as observed in boreholes. 4 figures, 2 tables

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

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

Selection of areas for testing in the Eleana formation: Paleozoic geology of western Yucca Flat

Energy Technology Data Exchange (ETDEWEB)

Sweeney, J J

1984-07-01

The Paleozoic geology of NTS is reviewed to select an area for underground nuclear testing in shale. Constraints on possible areas, dictated by test program requirements and economics, are areas with topographic slope less than 5/sup 0/, depths to working point less than 3000 ft., and working points above the water table. The rock formation selected is Unit J (argillite) of the Mississippian age Eleana Formation. Within NTS, Western Yucca Flat is selected as the best area to meet the requirements. Details of the Paleozoic structure of western Yucca Flat are presented. The interpretation is based on published maps, cross-sections, and reports as well as borehole, refraction seismic, and gravity data. In terms of subsurface structure and areas where Eleana Formation Unit J occurs at depths between 500 ft to 3000 ft, four possible testing areas are identified. The areas are designated here as A, B, C and the Gravity High. Available data on the water table (static water level) is reviewed for western Yucca Flat area. Depth to the water table increases from 500 to 600 ft in Area A to 1500 ft or more in the Gravity High area. Review of the water table data rules out area A and B for testing in argillite above the water table. Area C is relatively unexplored and water conditions are unknown there. Thus, the Gravity High is selected as the most promising area for selecting testing sites. There is a dolomite thrust sheet of unknown thickness overlying the argillite in the Gravity High area. An exploration program is proposed to better characterize this structure. Finally, recommendations are made for procedures to follow for eventual site characterization of a testing site in argillite. 22 references, 12 figures, 1 table.

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

International Nuclear Information System (INIS)

Charpentier, D.

2001-11-01

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 SO 4 -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 SO 4 -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)

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

Far-field thermomechanical response of argillaceous rock to emplacement of a nuclear-waste repository

International Nuclear Information System (INIS)

McVey, D.F.; Thomas, R.K.; Lappin, A.R.

1980-08-01

Before heat-producing wastes can be emplaced safely in any argillaceous rock, it will be necessary to understand the far-field thermal and thermomechanical response of this rock to waste emplacement. This report presents the results of a first series of calculations aimed at estimating the far-field response of argillite to waste emplacement. Because the thermal and mechanical properties of argillite are affected by its content of expandable clay, its behavior is briefly compared and contrasted with that of a shale having the same matrix thermal properties, but containing no expandable clay. Under this assumption, modeled temperatures are the same for the two rock types at equivalent power densities and reflect the large dependence of in-situ temperatures on both initial power density and waste type. Thermomechanical calculations indicate that inclusion of contraction behavior of expandable clays in the assumed argillite thermal expansion behavior results, in some cases, in generation of a large zone in and near the repository that has undergone volumetric contraction but is surrounded by uniformly compressive stresses. Information available to date indicates that this contraction would likely result in locally increased fluid permeability and decreased in-situ thermal conductivity, but might well be advantageous as regards radionuclide retention, because of the increased surface area within the contracted zone. Assumption of continuous and positive expansion behavior for the shale eliminates the near-repository contraction and tensional zones, but results in near-surface tensional zones directly above the repository

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.

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

International Nuclear Information System (INIS)

Rebours, H.; Delay, J.; Vinsot, A.

2006-01-01

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 km 2 . 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)

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

International Nuclear Information System (INIS)

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

2011-01-01

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

DR Argillite Disposal R&D at LBNL

Energy Technology Data Exchange (ETDEWEB)

Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Xu, Hao [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-08-12

Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at the Department of Energy’s (DOE) Office of Nuclear Energy, LBNL’s research activities have focused on understanding and modeling EDZ evolution and the associated coupled processes and impacts of high temperature on parameters and processes relevant to performance of a clay repository to establish the technical base for the maximum allowable temperature. This report documents results from some of these activities. These activities address key Features, Events, and Processes (FEPs), which have been ranked in importance from medium to high, as listed in Table 7 of the Used Fuel Disposition Campaign Disposal Research and Development Roadmap (FCR&D-USED-2011-000065 REV0) (Nutt, 2011). Specifically, they address FEP 2.2.01, Excavation Disturbed Zone, for clay/shale, by investigating how coupled processes affect EDZ evolution; FEP 2.2.05, Flow and Transport Pathways; and FEP 2.2.08, Hydrologic Processes, and FEP 2.2.07, Mechanical Processes, and FEP 2.2.09, Chemical Process—Transport, by studying near-field coupled THMC processes in clay/shale repositories. The activities documented in this report also address a number of research topics identified in Research & Development (R&D) Plan for Used Fuel Disposition Campaign (UFDC) Natural System Evaluation and Tool Development (Wang 2011), including Topics S3, Disposal system modeling – Natural System; P1, Development of discrete fracture network (DFN) model; P14, Technical basis for thermal loading limits; and P15 Modeling of disturbed rock zone (DRZ) evolution (clay repository).

DR Argillite Disposal R&D at LBNL

International Nuclear Information System (INIS)

Zheng, Liange; Kim, Kunhwi; Xu, Hao; Rutqvist, Jonny

2016-01-01

Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at the Department of Energy's (DOE) Office of Nuclear Energy, LBNL's research activities have focused on understanding and modeling EDZ evolution and the associated coupled processes and impacts of high temperature on parameters and processes relevant to performance of a clay repository to establish the technical base for the maximum allowable temperature. This report documents results from some of these activities. These activities address key Features, Events, and Processes (FEPs), which have been ranked in importance from medium to high, as listed in Table 7 of the Used Fuel Disposition Campaign Disposal Research and Development Roadmap (FCR&D-USED-2011-000065 REV0) (Nutt, 2011). Specifically, they address FEP 2.2.01, Excavation Disturbed Zone, for clay/shale, by investigating how coupled processes affect EDZ evolution; FEP 2.2.05, Flow and Transport Pathways; and FEP 2.2.08, Hydrologic Processes, and FEP 2.2.07, Mechanical Processes, and FEP 2.2.09, Chemical Process-Transport, by studying near-field coupled THMC processes in clay/shale repositories. The activities documented in this report also address a number of research topics identified in Research & Development (R&D) Plan for Used Fuel Disposition Campaign (UFDC) Natural System Evaluation and Tool Development (Wang 2011), including Topics S3, Disposal system modeling - Natural System; P1, Development of discrete fracture network (DFN) model; P14, Technical basis for thermal loading limits; and P15 Modeling of disturbed rock zone (DRZ) evolution (clay repository).

An experimental study of the thermal conductivity: application of EST 205 borehole of Meuse/Haute Marne site (ANDRA); Etude experimentale de la conductivite thermique: application au forage EST 205 du site de Meuse/Haute Marne (ANDRA)

Energy Technology Data Exchange (ETDEWEB)

Jorand, R

2006-10-15

The determination of the thermal properties of clayey rocks is fundamental for predicting the behaviour a radioactive waste geological repository, and geothermal and oil reservoirs. The main objectives of this thesis work were to 1) better understand the effects of the parameters controlling the thermal conductivity, 2) study to which extent the laboratory measurements can be extrapolated to the field, and 3) find relationships between the thermal conductivity and other quantities easier to measure on the field, e.g. the P- and S- wave velocities. The study was conducted on 24 cores of marls carbonates and argillites coming from the EST205 borehole of the M/HM site (ANDRA). After a complete characterisation of the samples, their thermal conductivities were measured using a stationary method. The borehole was drilled with a special oil-based mud to avoid damaging the argillites, and many logs were available. Hence, it is ideal to study the properties of clayey rocks and compare them with field data. The results show the major effect of the microstructure (mainly the particles orientation), which causes the important anisotropy of the thermal conductivity in the marls and argillites. For all lithologies, linear relationships between the conductivity and the P- and S- wave velocities were obtained. The application of this experimental law to the sonic log helped building a synthetic log of thermal conductivity. Finally, we developed a heat probe, which allows measurements in function of temperature and saturation. We showed with this method that the thermal conductivity increases quasi-linearly with the saturation in a sandstone and a carbonate samples. (author)

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

International Nuclear Information System (INIS)

Boulin, P.

2008-10-01

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)

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

International Nuclear Information System (INIS)

Robinet, J.C.; Talandier, J.; Davy, C.A.; Ghayaza, M.; Skoczylas, F.; Troadec, D.; Sardini, P.

2012-01-01

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

Kinetics and reversibility of radionuclide sorption reactions with rocks. Progress report for fiscal year 1979

International Nuclear Information System (INIS)

Barney, G.S.; Brown, G.E.

1979-01-01

Sorption-desorption reactions of cesium, strontium, neptunium, americium, and plutonium on basalt, granite, and argillite were observed for 218 days. Equilibrium in batch experiments was not reached for most radionuclides even after this long time. Reactions of the crushed rock with ground waters (dissolution, hydrolysis, precipitation, etc.) also did not reach equilibrium after 150 days. The dissolution of basalt is accompanied by the formation of colloidal particles which contain Si, Fe, Ca, and Al. These colloids sorb Cs, Sr, Am, and Pu during equilibration. Some of the colloids pass through 0.3-μm flters, are not retained even on 0.01-μm filters and, therefore, cause calculated K/sub d/ values to be too low. Samples of crushed basalt, granite, and argillite were artificially weathered by continuous leaching with distilled water for 6 months both in air and in an oxygen-free stream of nitrogen gas. The weathered rock was then characterized for surface area, surface structure, cation exchange capacity, and composition of weathered surface on the rock. Comparisons were made of radionuclide sorption (after 14 days) on fresh rock, rock weathered in air, and rock weathered in N 2 . Sorption on rocks weathered in N 2 generally is less than on rock weathered in air. This is possibly due to the lack of an Fe(OH) 3 coating on the rock weathered in N 2 . The Fe(OH) 3 is known to scavenge cations and silica from solution. Sorption of Cs, Si, Am, and Pu is strongly affected by weathering basalt and argillite. However, the cation exchange capacity is changed very little, suggesting that ion exchange plays a minor role in sorption of these radionuclides

When did the Penglai orogeny begin on Taiwan?: Geochronological and petrographic constraints on the exhumed mountain belts and foreland-basin sequences

Science.gov (United States)

Chen, W. S.; Syu, S. J.; Yeh, J. J.

2017-12-01

Foreland basin receives large amounts of synorogenic infill that is eroded from the adjacent exhumed mountain belt, and therefore provides the important information on exhumation evolution. Furthermore, a complete stratigraphic sequence of Taiwan mountain belt consists of five units of Miocene sedimentary rocks (the Western Foothills and the uppermost sequence on the proto-Taiwan mountain belt), Oligocene argillite (the Hsuehshan Range), Eocene quartzite (the Hsuehshan Range), Eocene-Miocene slate and schist (Backbone Range), and Cretaceous schist (Backbone Range) from top to bottom. Based on the progressive unroofing history, the initiation of foreland basin received sedimentary lithic sediments from the uppermost sequence of proto-Taiwan mountain belt, afterwards, and receiving low- to medium-grade metamorphic lithic sediments in ascending order of argillite, quartzite, slate, and schist clasts. Therefore, the sedimentary lithics from mountain belt were deposited which represents the onset of the mountain uplift. In this study, the first appearance of sedimentary lithic sediments occurs in the Hengchun Peninsula at the middle Miocene (ca. 12-10 Ma). Thus, sandstone petrography of the late Miocene formation (10-5.3 Ma) shows a predominantly recycled sedimentary and low-grade metamorphic sources, including sandstone, argillite and quartzite lithic sediments of 10-25% which records erosion to slightly deeper metamorphic terrane on the mountain belt. Based on the results of previous thermogeochronological studies of the Yuli belt, it suggests that the middle Miocene occurred mountain uplift. The occurrence of low-grade metamorphic lithic sediments in the Hengchun Peninsula during late Miocene is coincident with the cooling ages of uplift and denuded Yuli schist belt at the eastern limb of Backbone Range.

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)

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)

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)

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)

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)

Thermo-hydro mechanical modeling in unsaturated hard clay: application to nuclear waste storage

International Nuclear Information System (INIS)

Jia, Y.

2006-07-01

This work presents an elastoplastic damage model for argillite in unsaturated conditions. A short resume of experimental investigations is presented in the first part. The results obtained show an important plastic deformation coupled with damage induced by initiation and growth of microcracks. Influences of water content on the mechanical behaviour are also investigated. Based on experimental data and micro-mechanical considerations, a general constitutive model is proposed for the poro-mechanical behavior of argillite in unsaturated conditions. The time dependent creep has also been incorporated in they model. The performance of the model is examined by comparing numerical simulation with experimental data in various load paths under saturated and unsaturated conditions. Finally, the model is applied to hydro-mechanical coupling study of the REP experiment and thermo-hydro-mechanical coupling study of the HE-D experiment. A good agreement is obtained between experimental data and numerical predictions. It has been shown that the proposed model describe correctly the main features of the mechanical behaviour of unsaturated rocks. (author)

Use of geophysical methods for determination of physico-mechanical properties of coal-bearing rocks in wells of the Vorkutskoye field

International Nuclear Information System (INIS)

Grechukhin, V.V.; Iokhin, S.B.; Baklanov, V.G.; Chernikov, A.G.

1974-01-01

The total porosity (P), electric resistivity (Er), density, bulk density, water content, velocity of longitudinal elastic waves (Vl), intensity of natural γ-radiation, and polarization self-potential (Ps) are determined of the lithol. different interlayered sandstones, argillites, mudstones, siltstones, and concretions. A direct linear correlation exists between these parameters and the mineralogical composition, coefficient of sorting, and sedimentation conditions

Impact of porosity variation on diffusive transport: experimentation vs simulation

International Nuclear Information System (INIS)

Fatnassi, Ikram

2015-01-01

Reactions induced by the diffusion of reactants from different sources may alter rock confinement properties, and are therefore critical processes to assess short-term and long-term behaviour of rocks displaying a low permeability, such as argillites which are used as barriers in underground storage installation. In order to test transport-chemistry codes based on a continuous approach, the author of this research thesis reports the development and performance of simplest as possible experiments of sealing/dissolution diffusion, by using porous media of increasing complexity: compact sand, sintered glass, stoneware, chalk, until a material close to that envisaged within the frame of a storage like a Tournemire argillite. The principle of these experiments relies on the characterisation of the diffusive behaviour of an inert tracer within a porous medium submitted to dissolution reactions (attack of a carbonate matrix by an acid solution) and/or precipitation of mineral compounds (calcium oxalate, gypsum or barite) which results in an evolution of porosity and a modification of the diffusive transport of the studied tracer. At the end of the experiment, porous media and precipitates are characterised by SEM-EDS [fr

Application of mathematical model methods for optimization tasks in construction materials technology

Science.gov (United States)

Fomina, E. V.; Kozhukhova, N. I.; Sverguzova, S. V.; Fomin, A. E.

2018-05-01

In this paper, the regression equations method for design of construction material was studied. Regression and polynomial equations representing the correlation between the studied parameters were proposed. The logic design and software interface of the regression equations method focused on parameter optimization to provide the energy saving effect at the stage of autoclave aerated concrete design considering the replacement of traditionally used quartz sand by coal mining by-product such as argillite. The mathematical model represented by a quadric polynomial for the design of experiment was obtained using calculated and experimental data. This allowed the estimation of relationship between the composition and final properties of the aerated concrete. The surface response graphically presented in a nomogram allowed the estimation of concrete properties in response to variation of composition within the x-space. The optimal range of argillite content was obtained leading to a reduction of raw materials demand, development of target plastic strength of aerated concrete as well as a reduction of curing time before autoclave treatment. Generally, this method allows the design of autoclave aerated concrete with required performance without additional resource and time costs.

Natural isotope tracing of hydric transfers in a very low porosity clay stone formation: the argilites of Tournemire (France)

International Nuclear Information System (INIS)

Moreau-Le Golvan, Y.

1997-01-01

Since 1988, the experimental site of the French Institute for Protection and Nuclear Safety Safety (IPSN) situated in a tunnel near Tournemire (Aveyron, France), is studied in order to develop techniques and methods for the characterization of water behaviour in a clay-stone formation with very low water content and very low permeability. Isotope geochemistry was used to define the fluid transfer modalities. After the development development of the improvement of sampling techniques, the measurement of the stable isotope contents (oxygen - 18, deuterium, carbon-13) and radioactive isotope contents (tritium, carbon-14, chlorine-36) of fluids (pore water, fracture water) and solids (calcite fracture fillings) allowed to distinguish several origins and behaviours of water in the massif. The stable isotope distribution of pore water could be due to a diffusion driven mixing between argillite formation water and water from karsts, over and underlying the argillite formation. In this hypothesis, the time needed to establish the distribution profile should be longer than 5 million years. The role of the fractures seems complex, with indications of local paleo-transfers from the matrix to the fracture, and indications of transfers from the karstic aquifer. (author)

ANALYSIS OF DEFORMABILITY OF ANISOTROPIC AGRILLITE CLAYSTONES

Directory of Open Access Journals (Sweden)

Ponomaryov Andrey Budimirovicn

2017-08-01

Full Text Available In the paper, the results of deformability study of agrillite claystones are used for determination of the Jointed rock model parameters. The number of stamp, pressuremeter and compressive tests allowed to research anisotropic deformability of argillite claystone in vertical and horizontal direction. The following problems were solved during the study: 1 the in-place and laboratory experiments to calculate the anisotropy coefficient were done for anisotropic agrillite claystones with both natural moisture and total water saturation; 2 the deformation parameters were determined and the numerical simulation of the stress-strain state of claystone in field tests was carried out with the use of Plaxis 2D software application; 3 the comparative analysis was done for calculated claystone deformation and the values obtained during the in-place tests. The authors proved that agrillite claystones shows two times less deformation under loading in the horizontal direction than vertically. The ratio is obtained to determine the parameters for numerical simulation of the Jointed Rock model used as a practical tool for analysis of stress-strain behavior of anisotropic soils. The authors provided a recommended practice for consideration of specific properties of argillite claystones when carrying out foundation works.

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

International Nuclear Information System (INIS)

Comparon, L.

2005-06-01

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)

Engineered analogues of cement/clay interactions in the Tournemire experimental platform (France): a coupled mineralogical and geochemical approach to track tiny disturbances

International Nuclear Information System (INIS)

Techer, Isabelle; Michel, Pauline; Tinseau, Elisabeth; Devol-Brown, Isabelle; Bartier, Daniele; Boulvais, Philippe; Suchorski, Krzysztof

2012-01-01

A scientific program has been especially established to better understand the high-pH fluids / clay interactions through a mineralogical and geochemical study of three engineered analogues available by means of the IRSN Tournemire experimental platform. This platform, located in Aveyron (France), is based on a tunnel, excavated between 1882 and 1886 through Domerian marls and Toarcian argillites, and is dedicated since 1990 to multidisciplinary research programs. Different contexts presenting the argillite formation in contact with a cementitious material are encountered and are linked to its historical construction and scientific evolution. These rare examples of cement / clay contacts maintained over time scales ranging from a few years to a hundred of years are studied as engineered analogues of a deep geological storage. This approach is moreover completed by experiments (diffusion and advection) performed in laboratory over shorter time and smaller space scales in order to discriminate and control the major parameters involved in such interactions (details are given in another paper). This paper presents the scientific program developed on the three engineered analogues: tunnel walls recovered by lime after excavation; four concreted exploration boreholes; two experimental research galleries excavated in 2003

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)

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)

Small, J.S.; Steele, H.; Kwong, S.; Albrecht, A.

2010-01-01

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)

Chemical Entities in the foliated Argillite of coastal sedimentary ...

African Journals Online (AJOL)

PROF. O. E. OSUAGWU

2013-12-01

Dec 1, 2013 ... (360) gave rates of +20% of mineral palygorskites in the sample and 5-20% of mineral ..... Therapeutic and nutritional interest of ... Bentonite manufactured in Poland on acidity and chemical composition of milk, Medycyna.

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

International Nuclear Information System (INIS)

Lefranc, Marie

2007-01-01

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 km 2 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

Effect of chemical retention on anionic species diffusion in compacted clays

International Nuclear Information System (INIS)

Bazer-Bachi, Frederic

2005-01-01

Anionic radioisotopes are of particular importance within the framework of the calculated health risk associated with high-level and long-lived intermediate-level underground radioactive waste disposal. Therefore, the objective of this work is the construction of a transport model coupled with chemistry in order to quantify the behaviour of anionic solutes in the Callovo-Oxfordian (CO_x) argillite, the argillaceous host rock of the ANDRA Meuse/Haute-Marne underground laboratory. An experimental methodology was defined to characterize this migration, several experimental methods being implemented: batch experiments, laboratory columns and through-diffusion cells. The study of the diffusion of the non-sorbing anionic tracer "3"6Cl"- highlighted the fact that, due to anionic exclusion, anions only had access to a part of the porosity. The retention of "3"5SO_4"2"- and "1"2"5I- on CO_x argillite was then characterized, quantified by batch experiments and confirmed by other experimental methods. Nevertheless, their migration was less retarded than expected by a model based on batch experiments and on "3"6Cl"- diffusive data. This difference was explained by anion exclusion which reduced sorption site accessibility. Thus, the intensity of this phenomenon has to be considered to model anion migration in compacted clays. (author) [fr

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

Energy Technology Data Exchange (ETDEWEB)

Esnault, Loic [ECOGEOSAFE, Technopole de l' Environnement Arbois-Mediterranee, 13545 Aix en Provence (France); Libert, Marie; Bildstein, Olivier [CEA, DEN, DTN/SMTM/LMTE - 13108 Saint Paul lez Durance (France)

2013-07-01

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 O{sub 2}, NO{sub 3}{sup -}, Fe{sup 3+}, SO{sub 4}{sup 2-} and CO{sub 2}. Moreover, the accessibility and availability of H{sub 2} 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 H{sub 2} 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)

Diffusion of Cs, Ni, Pb, Se through MX80 bentonite and Bure argilite

International Nuclear Information System (INIS)

Kedziorek, M.A.M.; Bourg, A.C.M.

2010-01-01

Document available in extended abstract form only. In order to isolate nuclear waste in repositories from the biosphere two characteristics are required from the confining environment: adsorption as high as possible and permeability as low as possible. In France, bentonite (MX80) and argillite from the Bure underground laboratories are the candidates for the near- and far-field barriers, respectively. To investigate interactive diffusive transport, we performed a series of diffusion experiments in experimental cells. 'Through' diffusion and 'in' diffusion protocols were followed and performed for a cocktail of Cs, Ni, Pb and Se, this under a variety of conditions susceptible of affecting adsorption and diffusive transport, i.e. solid density, water pH and ionic strength. For the argillite experiments the solution pH and solid density are controlled by the solid. The MX80 bentonite was pretreated according to the proposed experimental solution pH and ionic strength. The reservoirs (downstream for the 'through' diffusion experiments and upstream for the 'in' diffusion experiments were sampled at regular intervals and analyzed for the elements of interests. At the end of the experiments the solids were sliced and the elemental content analyzed. A series of results will be presented and preliminary interpretation proposed

Formation of the gaseous phase of impurity elements from coal combustion at a thermal power plant

International Nuclear Information System (INIS)

Kizil'shtein, L.Ya.; Levchenko, S.V.; Peretyakt'ko, A.G.

1991-01-01

Data are reported on the distribution of impurity elements in their principal carriers: organic matter, iron sulfides, and clays. Tests with high-temperature combustion of coals and argillites indicate that elements associated with clay minerals largely remain in ash and slag. They do not pass to the gas phase - a factor to be considered in assessment of environmental impact from thermal power plants and specification of toxic concentration levels of impurity elements in coal

The evolution of the callovo-oxfordian argillite site, Eastern France

International Nuclear Information System (INIS)

Brulhet, J.

2004-01-01

In France, investigations on the feasibility of a repository for long-lived radioactive waste in a deep geological formation are carried out according to a regulatory framework (Basic Safety Rule, RFS III.2.f prescribing that the long-term geological evolution be taken into account to assess the dynamics of radionuclide transfers over the very long timescales involved. As a matter of fact, the period in the future is in the order of 1 million years and is consistent with the timescales of geological evolutions likely to be significant, especially at ground surface, due to fast and high-amplitude climate variations. In order to achieve that goal, external and internal geodynamic phenomena that would generate the potential evolution are studied both on the surface and deep underground. The purpose is to define a reference scenario where the evolution of the environment is induced by a series of very likely natural events in the future. In such a framework, the basis of the approach is to continue studying the geological evolution together with past situation analogies. The work also involves the description of one or several possible variations, such as potential extreme variations or disturbances of the evolution due to the impact of human activities. That aspect is particularly important with regard to the climate evolution, because of the hypotheses on the long-term effects of greenhouse gases. In that context, the goal is to forecast potential exceptional situations in the future with or without similar conditions in the past. (author)

Modelling glass alteration in an altered argillaceous environment

International Nuclear Information System (INIS)

Bildstein, O.; Trotignon, L.; Pozo, C.; Jullien, M.

2007-01-01

The long term behaviour of materials such as glass, steel and clay has been investigated in the context of deep geological disposal of radioactive wastes. The interactions between vitrified wastes, canister corrosion products (CPs) and clay are studied using a modified version of the reaction-transport code Crunch, especially looking at pH changes and possible cementation at the interface with the clayey materials. These perturbations may indeed affect the lifetime of glass matrix in deep repositories, e.g., high pH enhances the rate of glass alteration. This work focuses on the argillite of Bure. The calculations were performed at 323 K with a glass alteration rate switching from a high initial rate to a residual rate according to the sorption capacity of CPs. The time at which this sorption capacity is saturated is crucial to the system in terms of wastes package lifetime. The results show that the glass alteration imposes a high pH value at the interface with CPs and clay: up to a value of 9.2, compared to 7.3 which is the initial pH value in the argillite. Experimental data show that the rate of glass alteration is much higher in such pH conditions. For a R7T7-type glass, the rate is about five times higher at pH 9 than at pH 7. This pH perturbation migrates through the clayey domain as a result of the migration of mobile elements such as boron and sodium, and despite the existence of strong pH buffers in the argillite. The cementation of porosity at the interface between glass and clay is predicted by the model due to the massive precipitation of iron corrosion products and glass alteration products. At this point of the evolution of the system, the pH starts to decrease and the alteration rate of the glass could be significantly reduced. This porosity clogging effect is difficult to confirm by experiments especially since existing data on short term experiments tend to show a pervasive precipitation of silica in the domain instead of a localized precipitation

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

Science.gov (United States)

Wang, Tsing-Hai; Chen, Chin-Lung; Ou, Lu-Yen; Wei, Yuan-Yaw; Chang, Fu-Lin; Teng, Shi-Ping

2011-09-15

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 (100mg/L, 7.5 × 10(-4)mol/L and 0.01 mg/L, 7.5 × 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 determine concentration of surface sorption sites: the clay model (based on the cation exchange capacity plus surface titration results) and the iron oxide model (where the concentration of sorption sites is proportional to the surface area of argillite). It was found that the clay model led to better fitting than the iron oxide model, which is attributed to more amenable sorption sites (two specific sorption sites along with larger site

U-Pb (SHRIMP II) Age of zircons from ash tuffs of the upper vendian Chernyi Kamen formation (Sylvitsa group, Middle Urals)

International Nuclear Information System (INIS)

Ronkin, Yu.L.; Grazhdankin, D.V.; Maslov, A.V.; Mizens, G.A.; Matukov, D.I.; Krupenin, M.T.; Petrov, G.A.; Lepikhina, O.P.; Kornilova, A.Yu.

2006-01-01

To make more precise the model of correlation of the Middle Urals western slope upper vendian layers with the White Sea remote layers one carried out the SHRIMP-II procedure base U-Pb-dating of the volcanogenic zircons from the ash tuffs and of the volcanogenic zircon enclosing argillites of the Middle Urals Chernyi Kamen formation. The obtained age value of the studied zircons equal to 557+-13 million years is in line with the geological data [ru

Two-mica granites of northeastern Nevada.

Science.gov (United States)

Lee, D.E.; Kistler, R.W.; Friedman, I.; Van Loenen, R. E.

1981-01-01

The field settings are described and analytical data are presented for six two-mica granites from NE Nevada. High delta 18O and 87Sr/86Sr values indicate that all are S-type granite, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X ray, and other data are presented for the micas recovered from these granites. The muscovites are notably high in Fe2O3, FeO, and MgO. Except for one hydrobiotite, each of the biotites has an MgO content near 6.0 wt%. Two different types of two-mica granites are recognized in the area of this study. One type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides. This type probably resulted from anatexis of late Precambrian argillites under conditions of relatively low oxygen fugacity, along a line that roughly coincides with the westward disappearance of continental basement. In the other textural type of two-mica granite the micas are equigranular and there is a greater variety of accessory minerals. The magmatic evolution of this type also appears to reflect the influence of late Precambrian argillites; there may be age differences between the two types of two-mica granites.-Author

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.

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

Iron-clay interactions under a thermal gradient

International Nuclear Information System (INIS)

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

2010-01-01

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

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)

Jobard, Emmanuel

2013-01-01

The geological storage of the CO 2 is envisaged to mitigate the anthropogenic greenhouse gas emissions in the short term. CO 2 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 CO 2 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 CO 2 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 (N 2 or CO 2 ) 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 N 2 or CO 2 but are significantly amplified by the presence of CO 2 . 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/mm 2 with a size ranging between 10 and 100 μm 2 . The precipitation in the hot zone forms a micro-calcite fringe on the external part of the grains and fills the intergrain porosity

Past, present and predicted geochemical dynamics in the Callovian-Oxfordian argillites

International Nuclear Information System (INIS)

Gaucher, E.C.; Lerouge, C.; Tournassat, C.; Blanc, Ph.; Burnol, A.; Claret, F.; Marty, N.; Gailhanou, H.; Gaboreau, S.; Buschaert, S.; Altmann, S.

2010-01-01

The Callovian-Oxfordian formation in the Eastern part of the Paris Basin (COx) is currently under study for possible implantation of a deep underground nuclear waste repository. In this presentation, our purpose is to present the geochemical past of the formation from deposition to late diagenesis, then to describe the present equilibrium conditions and finally to give an overview of modeling for predicting effects of disposal facility-induced chemical perturbations on clay-rock characteristics. Mineralogical and isotopic data are the fingerprints of the clay-rock formation's sedimentary history. In the Jurassic sea, clay minerals sedimented to the sea floor along with other detrital minerals generated by erosion of the Hercynian massifs. Carbonates are represented by an important detrital bioclastic fraction originating from (i) the fauna from the different benthos levels and (ii) from the dismantling of the surrounding carbonate platforms. A petrological study provided evidence of the following diagenetic mineral sequence: 1) framboidal pyrite + micritic calcite replacing carbonate bioclasts and in bioturbations, 2) iron-rich euhedral carbonates, glauconite, 3) sparitic dolomite, celestite in residual porosity, 4) chalcedony 5) quartz/ calcite. Pyrites in bioturbations exhibit a wide range of δ 34 S, providing evidence of bacterial sulphate reduction processes. The lowest negative values are representative of pyrite precipitation in a marine environment with a permanent recharge in sulphate, whereas the higher pyrite δ 34 S values are indicative of pyrite precipitation in a closed system. The δ 34 S values of celestite reflect the last evolution stage of the system at which time bacterial activity was finished. The 87 Sr/ 86 Sr ratio of celestite is consistent with deposition from Jurassic marine-derived waters. Carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates whereas late diagenetic siderite is 13 C-depleted. The 13 C-depletion could be attributed to organic matter degradation. The δ 18 O values of late diagenetic chalcedony suggest precipitation from marine-derived pore waters at temperatures of maximum burial. Late calcite in veinlet reworking with chalcedony and celestite, and late euhedral quartz grains in a limestone from the top of the formation have lower δ 18 O values, suggesting a precipitation process from meteoric fluids. The transition from very active biotic diagenesis precipitates to abiotic diagenesis precipitates seems not to be due to a lack of organic carbon or sulphates but linked to the compaction of the clayey formation, which prohibits the cellular movements by reduction of the porosity. The second part of this presentation is devoted to current water/rock/gas equilibria in the formation. A geochemical model has been developed over the last 10 years based on evolving data regarding clay-rock mineralogy, its ion exchange properties, constraints on calco-carbonate equilibrium by CO 2 partial pressure measurements, leachable Cl and SO 4 concentrations and analyzed exchangeable cations. The current version of this model has benefited greatly from information on in-situ pore water composition obtained by the PAC experiments carried out in the Bure URL. New core sampling and analysis procedures were developed in order to reduce or quantify unwanted experimental side reactions such as sample oxidation and soluble mineral dissolution that affect measured SO 4 concentrations and exchangeable cation distributions. The model considers phase equilibria only with minerals that are observed in the formation including the principal clay phases. The model has been used to calculate the composition of mobile pore water in the Callovo-Oxfordian clay-rock and validated against measurements of water chemistry made in Bure underground research laboratory. The model reproduces the measured in situ pore-water composition without any estimated parameters, all required parameters being obtained from core sample analysis. The robustness of our model with respect to uncertainties in the log K values of clay phases was also demonstrated. Large uncertainties in log K values for clay minerals have relatively small effects on modeled pore-water compositions. Finally, the understanding of the current geochemical conditions is a prerequisite for modeling the chemical perturbations that will be induced by the disposal. Theses perturbations are linked to (i) the ventilation of the tunnels and subsequent oxidation of the rock that results e.g. to the precipitation of gypsum at the concrete/COx interfaces, (ii) production of alkaline solutions by the massive presence of cement and concrete in the disposal, (iii) H 2 (g) and iron(II) production and release due to the corrosion of the steel canisters, (iv) aqueous silica release due to the dissolution of the nuclear glass, (v) NO 3 - plume due to the alteration of the bituminous canisters, and (vi) thermal perturbation. Some 'good practice' rules govern the establishment of a careful and meaningful numerical modeling, including an appropriate meshing, a coherent and complete thermodynamic database, an appropriate selection of minerals, a correct understanding of the regulation of the partial pressure of CO 2 , etc. Various test cases have been studied in order to answer some key questions relative to the extension of the perturbations and their consequences on the mineralogy and physical properties of the clayey formation: e.g. clogging of the porosity, increase of the gas pressure or increase of the mechanical stresses due to the precipitation of the minerals. (authors)

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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

Burnol, A.; Blanc, P.; Tournassat, C.; Lassin, A.; Gaucher, E.C.

2005-01-01

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 CO 2 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 UO 2 oxidative dissolution and uranium migration., Journal of Contaminant Hydrology, 61, 1-4, 303-312; [2] Parkhurst D.L., Appelo C.A.J. (1999) - User

Evaluation of Used Fuel Disposition in Clay-Bearing Rock

Energy Technology Data Exchange (ETDEWEB)

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

2015-09-04

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

The ophiolitic North Fork terrane in the Salmon River region, central Klamath Mountains, California

Science.gov (United States)

Ando, C.J.; Irwin, W.P.; Jones, D.L.; Saleeby, J.B.

1983-01-01

The North Fork terrane is an assemblage of ophiolitic and other oceanic volcanic and sedimentary rocks that has been internally imbricated and folded. The ophiolitic rocks form a north-trending belt through the central part of the region and consist of a disrupted sequence of homogeneous gabbro, diabase, massive to pillowed basalt, and interleaved tectonitic harzburgite. U-Pb zircon age data on a plagiogranite pod from the gabbroic unit indicate that at least this part of the igneous sequence is late Paleozoic in age.The ophiolitic belt is flanked on either side by mafic volcanic and volcaniclastic rocks, limestone, bedded chert, and argillite. Most of the chert is Triassic, including much of Late Triassic age, but chert with uncertain stratigraphic relations at one locality is Permian. The strata flanking the east side of the ophiolitic belt face eastward, and depositional contacts between units are for the most part preserved. The strata on the west side of the ophiolitic belt are more highly disrupted than those on the east side, contain chert-argillite melange, and have unproven stratigraphic relation to either the ophiolitic rocks or the eastern strata.Rocks of the North Fork terrane do not show widespread evidence of penetrative deformation at elevated temperatures, except an early tectonitic fabric in the harzburgite. Slip-fiber foliation in serpentinite, phacoidal foliation in chert and mafic rocks, scaly foliation in argillite, and mesoscopic folds in bedded chert are consistent with an interpretation of large-scale anti-formal folding of the terrane about a north-south hinge found along the ophiolitic belt, but other structural interpretations are tenable. The age of folding of North Fork rocks is constrained by the involvement of Triassic and younger cherts and crosscutting Late Jurassic plutons. Deformation in the North Fork terrane must have spanned a short period of time because the terrane is bounded structurally above and below by Middle or Late

Geology of the UE17e drill hole, Area 17, Nevada Test Site

International Nuclear Information System (INIS)

Hodson, J.N.; Hoover, D.L.

1979-03-01

The UE17e drill hole, located at the northwest corner of Syncline Ridge, was cored from 3.05 m (10 ft) to a total depth of 914.4 m (3,000 ft) in unit J (Mississippian) of the Eleana (Devonian and Mississippian) to obtain samples for mineral, chemical, and physical-property analyses. UE17e penetrated 73.5 m (241 ft) of the quartzite subunit and 840.9 m (2,759 ft) of the argillite subunit of unit J. Less than 0.4 percent quartzite is present in the argillite subunit. Dips range from 12 0 to 18 0 . Twenty-three faults were observed in the core or on geophysical logs. Most of these faults affect only a few meters of the core and probably have displacements of a few meters. The majority of fractures are parallel to bedding planes. Fracture frequency ranges from 3.4 to 9.4 fractures per meter in the upper part of the cored interval and 1.4 to 5.9 fractures per meter in the lower part of the cored interval. The core index indicates that the lower part of the hole is more competent than the upper part. Lower competency in the upper part of the hole may be caused by weathering and/or near-surface stress relief. Physical, mechanical, and thermal property measurements indicate that bedding and fracturing are the major factors in variation of properties between samples. 17 figures, 10 tables

Mineralogical, chemical, and petrographic analysis of selected rock samples

International Nuclear Information System (INIS)

Roy, D.M.

1976-01-01

I. The majority of rocks examined from the NTS were found to be siltstones, varying from coarse into the very fine siltstone range, and containing > 60% quartz, usually much higher. Samples of the UEIL series of cores, in contrast, had a large clay mineral fraction, as well as some carbonate present. A few were intermediate silty claystones or argillites. Microphotographs are included to illustrate the variations in texture observed, while most of the data obtained are summarized in tabular form. II. Seven Michigan Salina evaporite specimens were analyzed

Hf isotope evidence for variable slab input and crustal addition in basalts and andesites of the Taupo Volcanic Zone, New Zealand

DEFF Research Database (Denmark)

Waight, Tod Earle; Troll, Valentin R.; Gamble, J.A.

2017-01-01

-Nd isotopes. Here we present new Hf isotope data for a selection of volcanic rocks and crustal lithologies fromthe Taupo Volcanic Zone (TVZ), NewZealand and propose that the scatter in Hf-Nd isotopes indicates heterogeneity in the parental magmas prior to interactions with crustal lithologies. The observed......, whereas younger lavas have probably interacted more with mid- to shallow crustal meta-sedimentary greywacke-argillite lithologies of the Permian to Cretaceous composite Torlesse Terrane. Hf-Nd isotopic compositions of meta-igneous granulite xenoliths from Mt. Ruapehu are consistent with previous...

Profiles of chloride and water stable isotope in porewater obtained from a 2000 m-deep borehole through the Mesozoic sedimentary series in the East of France

International Nuclear Information System (INIS)

Bensenouci, F.; Michelot, J.L.; Matray, J.M.; Savoye, S.

2010-01-01

Document available in extended abstract form only. A method to obtain information about fluid flow and solute transport in porous media with low hydraulic conductivity and low water content is based on the study of the natural tracer distribution in pore water. This approach was previously applied to the Callovo-Oxfordian argillites, studied by Andra at the Bure URL (East of France), using several natural tracer profiles ( 4 He, 2 H, 18 O, Cl - , 37 Cl). These profiles were interpreted as the result of a diffusive exchange between pore water in the aquitard and groundwater in the surrounding aquifers. However, at the Bure URL, and in contrast to other investigated argillaceous formations, the concentrations of tracers in lower aquifer groundwater may be higher than those in argillite pore water and increase with depth. The continuity of the profiles and the origin of pore water salinity remained questionable. This study aims at presenting and interpreting chloride and stable isotope profiles in pore water through more than 800 m of sediments, from the lower Oxfordian to the lower Hettangian. Drill-core samples were collected from the 2000 m-deep borehole (EST 433) drilled by Andra in the so-called 'Transposition Zone', located north to the Bure URL. In the framework of the TAPPS 2000 programme, twenty-five core samples were collected from the Oxfordian to the lower Hettangian during the drilling campaign, and in-situ conditioned. The chloride concentrations in pore water were firstly estimated by aqueous leaching, using a geochemical porosity two times smaller than the porosity measured by heating at 150 deg. C. After this estimation of pore water salinities, the radial diffusion and vapour exchange methods were applied to determine the stable isotope and anion concentrations in pore water. The deuterium contents of pore water derived from the vapour exchange experiments describe a classical bell-shape profile in the Callovo-Oxfordian argillites with an

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

International Nuclear Information System (INIS)

Vales, F.

2008-12-01

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

Deformation and damage modes of deep argillaceous rocks under hydro-mechanical stresses; Modes de deformation et d'endommagement de roches argileuses profondes sous sollicitations hydro-mecaniques

Energy Technology Data Exchange (ETDEWEB)

Vales, F.

2008-12-15

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 {mu}.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

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

International Nuclear Information System (INIS)

Gonzales, S.; Johnson, K.S.

1981-01-01

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

Contribution of natural tracers for understanding transfers through argillaceous formations

International Nuclear Information System (INIS)

Bensenouci, F.

2010-01-01

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

Iodine and selenium migration through argillaceous rocks

International Nuclear Information System (INIS)

Frasca, Benjamin

2011-01-01

Deep argillaceous formations are considered as potential host rock for high-level radioactive waste repository. Based on safety assessment calculations, active selenium ( 79 Se) and iodine ( 129 I) 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)

Preliminary geologic and geophysical data of the UE25a-3 exploratory drill hole, Nevada Test Site, Nevada

International Nuclear Information System (INIS)

Maldonado, F.; Muller, D.C.; Morrison, J.N.

1979-09-01

The UE25a-3 drill hole, located in the Calico Hills area, was drilled as part of an effort to evaluate the Calico Hills area as a possible nuclear waste repository site. The purpose of the drill hole was to verify the existence of an intrusive crystalline body in the subsurface and to determine the stratigraphy, structure, and nature of fractures of the cored rocks. Cored samples were obtained for mineral, chemical, and material property analyses. Numerous high-angle faults and brecciated zones were intersected by the drill hole. The units cored were intensely fractured with fracture analysis of the core consisting of frequency of fractures, dips of fractures, open and closed (sealed) fractures and types of fracture sealing or coating material. Twenty-four hundred and thirty fractures, representing approximately 30 percent of the fractures present, indicate an average fracture frequency of 13.2 fractures per meter, predominantly high-angle dips with 66 percent of the fractures closed. Fractures in the argillite interval are sealed or coated predominantly with kaolinite, nacrite, and dickite. Calcite, chlorite, and magnetite are present in fractures in the altered argillite interval. Fractures in the marble interval are sealed or coated with calcite, dolomite, and ferruginous clay. The core index indicates that the lower half of the drilled interval is more competent than the upper half. Borehole geophysical logs were run by the Birdwell Division of Seismograph Service Corporation for geologic correlations and lithologic characterizations. The logs include: caliper, density, resistivity, spontaneous potential, Vibroseis, 3-D velocity, neutron, and gamma-ray logs

M4FT-16LL080302052-Update to Thermodynamic Database Development and Sorption Database Integration

Energy Technology Data Exchange (ETDEWEB)

Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.. Physical and Life Sciences; Wolery, T. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Akima Infrastructure Services, LLC; Atkins-Duffin, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Global Security

2016-08-16

This progress report (Level 4 Milestone Number M4FT-16LL080302052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Argillite Disposal R&D Work Package Number FT-16LL08030205. The focus of this research is the thermodynamic modeling of Engineered Barrier System (EBS) materials and properties and development of thermodynamic databases and models to evaluate the stability of EBS materials and their interactions with fluids at various physico-chemical conditions relevant to subsurface repository environments. The development and implementation of equilibrium thermodynamic models are intended to describe chemical and physical processes such as solubility, sorption, and diffusion.

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

International Nuclear Information System (INIS)

Peyaud, J.B.

2002-04-01

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 δ 18 O 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)

Redox reactions induced by hydrogen in deep geological nuclear waste disposal

International Nuclear Information System (INIS)

Truche, L.

2009-10-01

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 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 2 gas lead to an important H 2 S production, in only few hours at 250 C to few months at 90 C. In order to explore whether H 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 2 partial pressure exhibits a high activation energy (131 kJ/mol) and requires H 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 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 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 2 reactive geochemistry. (author)

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.)

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

Science.gov (United States)

Mars, John C.; Rowan, Lawrence 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 μm and 2.31–2.33 μm, whereas the sandstone, argillite, and adjacent alluvial deposits exhibit intense Si-O absorption near 8.7 μm caused mainly by quartz and Al-OH absorption near 2.20 μm 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 μm (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 preexisting 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 μm, respectively, which suggest that the contact aureole rocks contain muscovite, 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

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

International Nuclear Information System (INIS)

Patriarche, D.

2001-01-01

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 18 O 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)

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

International Nuclear Information System (INIS)

Zheng, Liange; Rutqvist, Jonny; Kim, Kunhwi; Houseworth, Jim

2015-01-01

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.

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

International Nuclear Information System (INIS)

Lefort, Philippe

2014-01-01

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)

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.

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

International Nuclear Information System (INIS)

Daniels, W.R.

1981-01-01

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

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)

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

International Nuclear Information System (INIS)

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)

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

International Nuclear Information System (INIS)

Wileveau, Yannick; Su, Kun; Ghoreychi, Mehdi

2007-01-01

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)

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

International Nuclear Information System (INIS)

Paszkuta, M.

2005-06-01

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)

The Callovo-Oxfordian of the Paris Basin: From its geological context to the modelling of its properties; Le Callovo-Oxfordien du bassin de Paris: du contexte geologique a la modelisation de ses proprietes

Energy Technology Data Exchange (ETDEWEB)

Anon

2006-10-15

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.)

Current status of crushed rock and whole rock column studies

International Nuclear Information System (INIS)

Vine, E.N.; Daniels, W.R.; Rundberg, R.S.; Thompson, J.L.

1980-01-01

Measurements on a large number of crushed rock columns of tuff, granite, and argillite are discussed. The isotopes 85 Sr, 137 Cs, 133 Ba, 141 Ce, 152 Eu, /sup 95m/Tc, and 233 U were used. Flow rates were varied from approx. 30 to approx. 30000 m/y. Other parameters studied include isotope concentration and atmosphere. The sorption ratios calculated were compared with batch sorption ratios on the same samples. Methods of studying the movement of radionuclides through whole rock cores are described. The problems associated with sealing the cores to prevent leaking along the exterior surface and one possible solution are discussed. The strontium sorption ratio obtained by elution of one solid tuff core is compared with the batch and crushed rock column sorption ratios

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)

Ecohydrological Consequences of Critical Zone Structure in the Franciscan Formation, Northern California Coast Ranges

Science.gov (United States)

Hahm, W. J.; Dietrich, W. E.; Dawson, T. E.; Lovill, S.; Rempe, D.

2016-12-01

Water availability regulates ecosystem function, particularly in seasonally dry climates where lack of moisture in the growing season acts as an ecological bottleneck. Water within hillslopes is extracted by plants during transpiration and also delivered to streams to support baseflow for riparian ecosystems and human use. How water is stored and then released from hillslopes is strongly influenced by the structure of the critical zone (CZ) that emerges from the complex interaction of lithology, climate, and tectonics. Here we show how contrasting CZ development has extreme ecohydrological consequences in the seasonally dry climate of the Northern California Coast Ranges. To explore how the CZ transmits and stores water, we studied hydrologic dynamics at two sites with similar climate across belts of the Franciscan Formation in the Eel River CZO. We monitored plant water use, precipitation inputs and stream runoff, groundwater and vadose zone moisture dynamics and documented near-surface hydraulic conductivity and runoff-generation processes. We investigated CZ structure via boreholes and geophysical methods. We find that CZ thickness determines the extent to which hillslopes `shed' or `store' wet season precipitation, and fundamentally controls the structure of plant communities and summer low-flows. In a climate where winter precipitation regularly exceeds 2000 mm, the thin CZ of the sheared argillite matrix Central belt rapidly fills, resulting in wet-season saturation overland flow that drives flashy winter runoff in channels that then quickly run dry in the early summer. The maximum unsaturated moisture storage of approximately 200 mm is sufficient to host an ecologically diverse yet sparsely forested oak savanna. In contrast, the thick CZ of the interbedded argillite and greywacke Coastal belt stores up to 600 mm of winter precipitation in the unsaturated zone and a seasonal groundwater system within fractured bedrock provides year-round flow to channels

Lower Paleozoic deep-water facies of the Medfra area, central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1997

Science.gov (United States)

Dumoulin, Julie A.; Bradley, Dwight C.; Harris, Anita G.; Repetski, John E.

1999-01-01

Deep-water facies, chiefly hemipelagic deposits and turbidites, of Cambrian through Devonian age are widely exposed in the Medfra and Mt. McKinley quadrangles. These strata include the upper part of the Telsitna Formation (Middle-Upper Ordovician) and the Paradise Fork Formation (Lower Silurian-Lower Devonian) in the Nixon Fork terrane, the East Fork Hills Formation (Upper Cambrian-Lower Devonian) in the East Fork subterrane of the Minchumina terrane, and the chert and argillite unit (Ordovician) and the argillite and quartzite unit (Silurian- Devonian? and possibly older) in the Telida subterrane of the Minchumina terrane.In the western part of the study area (Medfra quadrangle), both hemipelagic deposits and turbidites are largely calcareous and were derived from the Nixon Fork carbonate platform. East- ern exposures (Mt. McKinley quadrangle; eastern part of the Telida subterrane) contain much less carbonate; hemipelagic strata are mostly chert, and turbidites contain abundant rounded quartz and lesser plagioclase and potassium feldspar. Deep-water facies in the Medfra quadrangle correlate well with rocks of the Dillinger terrane exposed to the south (McGrath quadrangle), but coeval strata in the Mt. McKinley quadrangle are compositionally similar to rocks to the northeast (Livengood quadrangle). Petrographic data thus suggest that the Telida subterranes presently defined is an artificial construct made up of two distinct sequences of disparate provenance.Restoration of 90 and 150 km of dextral strike-slip on the Iditarod and Farewell faults, respectively, aligns the deep-water strata of the Minchumina and Dillinger terranes in a position east of the Nixon Fork carbonate platform. This restoration supports the interpretation that lower Paleozoic rocks in the Nixon Fork and Dillinger terranes, and in the western part of the Minchumina terrane (East Fork subterrane and western part of the Telida subterrane), formed along a single continental margin. Rocks in the

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)

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

International Nuclear Information System (INIS)

Bajpai, R.K.; Verma, A.K.; Maheshwar, Sachin

2016-01-01

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

Regional Geologic Evaluations for Disposal of HLW and SNF: The Pierre Shale of the Northern Great Plains

Energy Technology Data Exchange (ETDEWEB)

Perry, Frank Vinton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelley, Richard E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-14

The DOE Spent Fuel and Waste Technology (SWFT) R&D Campaign is supporting research on crystalline rock, shale (argillite) and salt as potential host rocks for disposal of HLW and SNF in a mined geologic repository. The distribution of these three potential repository host rocks is limited to specific regions of the US and to different geologic and hydrologic environments (Perry et al., 2014), many of which may be technically suitable as a site for mined geologic disposal. This report documents a regional geologic evaluation of the Pierre Shale, as an example of evaluating a potentially suitable shale for siting a geologic HLW repository. This report follows a similar report competed in 2016 on a regional evaluation of crystalline rock that focused on the Superior Province of the north-central US (Perry et al., 2016).

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

International Nuclear Information System (INIS)

Souley, Mountaka; Ghoreychi, Mehdi; Armand, Gilles

2010-01-01

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

Some clastic rocks as parent rocks in beech forests of Brezovica - Južni Kučaj

Directory of Open Access Journals (Sweden)

Joksimović Vesna

2003-01-01

Full Text Available On the large forest areas, where the measures of soil quality improvement are absent or rarely undertaken, the rocks are the sources of a great number of elements in plant nutrition and one of the factors affecting the contents of some elements in plants. The aim of the study is to determine the differences in the contents of Cu, Zn, Mn, Ni, Fe, Cd, Co, Pb and Cr in the beech leaves developed in the same climate conditions, on morphologically similar terrains, composed of different types of sedimentary rocks. This paper presents the study results of the contents of the above elements in argillites, sandstones (grauwackes and microconglomerates occurring as the parent rocks in high beech forests in the region of GJ Bogovina (Brezovica Južni Kučaj and in the leaves of beech developed on these rocks.

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

International Nuclear Information System (INIS)

Davy, C. A.; M'Jahad, S.; Skoczylas, F.; Talandier, J.; Ghayaza, M.

2012-01-01

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

Selenium behaviour in the presence of minerals and under hydrogen atmosphere

International Nuclear Information System (INIS)

Jeanson, A.; Gebala, N.; Fattahi, M.; Landesman, C.; Granbow, B.

2010-01-01

Document available in extended abstract form only. In the framework of nuclear waste handling, radionuclide diffusion ability in soil has to be studied in order to better evaluate the risks of infiltration of radioactive elements in our environment. Indeed, radionuclide behaviour is deeply dependent of the soil characteristics, like its composition, pH, potentials, or the water composition. In the case of a deep geological depository, the high-level radioactive waste will be put in a glass matrix, confined in a steel container. Those containers are exposed to corrosion phenomena, forming ferrous minerals, hydrogen gas, and potentially leading to radionuclide leaks. In this case, radionuclides could be in the presence of minerals and hydrogen in a reducing environment. 79 Selenium is expected to be present as a fission product of 235 U. It is present at the oxidation state (+IV) in the glass matrix, but under reductive conditions ([-400;-300] mV (E.N.H.)) can be under the form of selenide (Se(-II)). Those reductive condition could exist in Callovo-Oxfordian soil (COX) in the presence of H 2 gas and Fe(II) coming from the containers corrosion. Thus, our study focuses on Se(IV) and Se(-II) behaviour in the presence of minerals (magnetite, and COX argillite), under hydrogen atmosphere. According to Martinez et al., selenium is sorbed on magnetite surface. When pH increases, selenium is less adsorbed on magnetite. Se(IV) sorption mechanism has been proposed by Mayant et al.: it implies the formation of two types of complexes in the inner sphere of magnetite surface. Moreover, Sheinost et al. show that synthetic nanoparticles of magnetite quantitatively reduce Se(IV) to Se(-II) in a few hours, leading to the formation of an iron selenide cluster close to Fe II 5 Fe III 2 Se 8 . While Se(IV) sorption on minerals has been broadly studied, very few data is found about Se(-II), due to its very high sensibility to oxidation causing its handling to be difficult. Suspensions of

Geologic Map of the Weaverville 15' Quadrangle, Trinity County, California

Science.gov (United States)

Irwin, William P.

2009-01-01

terrane is faulted against the west edge of the Central Metamorphic terrane, and its northerly trend is disrupted by major left-lateral offsets along generally west-northwest-trending faults. The serpentinized peridotite-gabbro complex that forms the western base of the terrane is the Permian North Fork ophiolite, which to the east is overlain by broken formation of mafic-volcanic rocks, red chert, siliceous tuff, argillite, minor limestone, and clastic sedimentary rocks. The chert and siliceous tuff contain radiolarians of Permian and Mesozoic ages, and some are as young as Early Jurassic (Pliensbachian). Similar Pliensbachian radiolarians are found in Franciscan rocks of the Coast Ranges. The Eastern Hayfork terrane is broken formation and melange of mainly chert, sandstone, argillite, and various exotic blocks. The cherts yield radiolarians of Permian and Triassic ages but none of clearly Jurassic age. Limestone bodies of the Eastern Hayfork terrane contain Permian microfaunas of Tethyan affinity. The Western Hayfork terrane, exposed only in a small area in the southwestern part of the quadrangle, consists dominantly of mafic tuff and dark slaty argillite. Sparse paleontologic data indicate a Mesozoic age for the strata. The terrane includes small bodies of diorite that are related to the nearby Wildwood pluton of Middle Jurassic age and probably are related genetically to the stratified rocks. The terrane is interpreted to be the accreted remnants of a Middle Jurassic volcanic arc. Shortly after intrusion by Shasta Bally batholith (approx. 136 Ma), much of the southern half of the Weaverville quadrangle was overlapped by Lower Cretaceous, dominantly Hauterivian, marine strata of the Great Valley sequence, and to a lesser extent later during Oligocene and (or) Miocene time by fluvial and lacustrine deposits of the Weaverville Formation. This map of the Weaverville Quadrangle is a digital rendition of U.S. Geological Survey Miscellaneous Field

Comparison of performance of concrete barriers in a clayey geological medium

International Nuclear Information System (INIS)

Trotignon, Laurent; Peycelon, Hugues; Bourbon, Xavier

2006-01-01

Cement based materials play an important role in the design and performance of future deep radioactive waste disposals. The type of materials selected for engineered barrier systems (EBS) is an important issue: protection of waste packages against corrosion and chemical degradation may be greatly enhanced by a proper choice and dimensioning. The long-term geochemical performance of two concrete types, CEM-I (pure Portland cement) and CEM-V (blended Portland, fly ash, blast furnace slag cement) was evaluated using reactive transport simulations of the interactions between the Callovo-Oxfordian mud-rock (argillite) and concrete EBS over periods up to 10 6 years at 25 deg. C. Simulations have been run with cylindrical geometry using the modeling tool Hytec 3.5 (ENSMP/CIG). Diffusion of solutes in the pore-water of the solid media was considered to be the dominant transport process. Different scenarios were studied, including the case of sulfate attack. Various assumptions on the transport properties of the EBS and the argillite medium have been considered and compared. The interactions between concrete, CEM-I or CEM-V, and mud-rock are in both cases predicted to lead to a significant clogging in the mud-rock, in the vicinity of the interface with the concrete EBS. However, the nature and extent of the EBS/mud-rock interface transformations greatly differ for the two materials considered. CEM-V, due to lower diffusion coefficients, keeps longer internal high pH conditions which are favorable to the waste packages from a chemical point of view. In addition, simulations predict that CEM-V material should have a better resistance to sulfate attack than CEM-I based barriers. In the case of CEM-I, the altered clay zone has a greater extent (up to 1.3 m in 400,000 y) and the drop of porosity is mainly due to zeolites and re-precipitated illite, quartz and calcite. For CEM-V, the altered clay zone is much smaller (less than 0.2 m in 400,000 y) and secondary smectite and

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

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

International Nuclear Information System (INIS)

Pham, Q.T.

2006-03-01

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

Fundamental approach to the analysis of radionuclide transport resulting from fluid flow through jointed media

International Nuclear Information System (INIS)

Erickson, K.L.

1981-02-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and Tertiary silicic tuffs in contact with solutions containing Cs, Sr or Pm indicated that most radionuclide sorption is associated with the surfaces of very small intergranular regions and that the rate of sorption is controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly to Rosen's solutions. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity, and sorption distribution coefficient

The underground laboratory. A unique scientific tool to design a reversible storage

International Nuclear Information System (INIS)

2010-07-01

The National Radioactive Waste Management Agency (Andra), was established by the December 1991 Waste Act as a public body in charge of the long-term management of all radioactive waste, under the supervision of the Ministry of Ecology, Energy, Sustainable Development and the Sea (formerly the Ministry of Industry and the Ministry of Environment), and the Ministry of Research. The Andra is carrying out studies on deep reversible waste storage for high-level and long living intermediate-level radioactive wastes thanks to the underground laboratory of its Meuse/Haute-Marne center. This brochure presents the geologic surveys which have led to the selection of the Callovo-Oxfordian argillite formation for the sitting of the underground lab and the underground architecture of the lab. The rock mechanic, heat transfer and rock-fluid interaction experiments carried out in the lab in collaboration with several scientific partners are briefly summarised

Geology, physical properties, and surface effects at Discus Thrower Site, Yucca Flat, Nevada Test Site

International Nuclear Information System (INIS)

Carr, W.J.; Miller, C.H.; Dodge, H.W. Jr.

1975-01-01

Geologic studies in connection with Project Discus Thrower have furnished detailed stratigraphic and structural information about northwestern Yucca Flat, Nevada Test Site. The Paleozoic rocks consist of a lower carbonate sequence, argillite of the Eleana Formation, and an upper carbonate sequence. The distribution of these rocks suggests that both top and bottom of the Eleana are structural contacts, probably thrusts or reverse faults. The overlying tuff includes several units recognized in the subsurface, such as the Fraction Tuff and tuff of Redrock Valley. Other units recognized include bedded tuff associated with the Grouse Canyon Member of Belted Range Tuff, and the Rainier Mesa and Ammonia Tanks Members of the Timber Mountain Tuff. The Timber Mountain and Grouse Canyon are extensively altered to montmorillonite (a swelling clay), possibly as a result of ponding of alkaline water. The overlying alluvium locally contains at the base a clayey, tuffaceous sandstone

Influence of coupling phenomena on the transport through compacted clays

Energy Technology Data Exchange (ETDEWEB)

Rosanne, M.; Koudina, N.; Adler, P.M. [IPGP, Paris (France); Tevissen, E. [ANDRA, Dept. Etude-Experimentation et Calcul, Chatenay Malabry (France)

2001-07-01

Our principal motivation was to study the influence of the coupling phenomena on transport through compacted clays. Coupled transports may occur when a pressure gradient {nabla}P, and electrical field E and a concentration gradient {nabla}C interact. These three gradients induce three fluxes. A flow is generated characterized by the seepage velocity U; a solute flux J{sub L} and a current density I are generated. Close to equilibrium, when the gradients are not to large, the problem is linear and the fluxes are linear functions of the gradients. A first series of experiments was performed with argillite to determine the diagonal properties, i.e., permeability, conductivity, and diffusion coefficient. In a second series of experiments, the voltage resulting from an imposed concentration gradient between two reservoirs separated by a clay sample was systematically measured; this corresponds to the coefficient L{sub 13}. (orig.)

Inventories of organic materials and complexing agents in intermediate-level long-lived parcels (Report PNGMDR 2013-2015)

International Nuclear Information System (INIS)

2014-01-01

This report presents an inventory of organic materials and of complexing agents they may produce within parcels of alpha wastes which are to be produced or are being currently produced. The report proposes the results of campaigns of measurements of degassing, and comparison with results of modelling studies. The assessment of degassing rates of parcels of alpha wastes is completed by an assessment of hydrogen produced by radiolysis of interstitial water within the concrete container. Thus, after a presentation of the main parcels used by the CEA for intermediate-level long-lived wastes, and of an inventory of wastes containing organic materials, this report describes the consequences of radiolysis on polymers, and describes the objectives of R and D studies. It reports measurements and presents simulation tools for heterogeneous wastes, homogeneous wastes, production of water-soluble degradation products, and transfer and adsorption of these products in the storage site argillite

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

International Nuclear Information System (INIS)

Villar, M. V.; Fernandez, A. M.; Melon, A. M.

2009-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Fernandez, A. M.; Melon, A. M.

2009-10-12

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.

Safety cases and siting processes

International Nuclear Information System (INIS)

Metlay, Daniel; Ewing, Rodney

2014-01-01

Central to any process for building a deep-mined geologic repository for high-activity radioactive waste is the development of a safety case. To date, such cases, in various forms have been elaborated for a variety of concepts for geologic disposal, including in salt, clay, argillite, crystalline rock (granite and gneiss) and volcanic tuff formations. In addition to the technical effort required to develop a safety case, increasingly nations have come to believe that it is also critical to obtain the consent of the region or community where the facility might be located. The purpose of this paper is to explore issues associated with just one aspect of consent-based siting: How can such a process be designed so that willingness to accept a site for a repository continues to be meaningful even as new technical knowledge and insights emerge during site characterisation? In short, what is the meaning of 'informed consent' in the context of repository development? (authors)

Spectral analysis of meteorites ablated in a wind tunnel

Science.gov (United States)

Drouard, A.; Vernazza, P.; Loehle, S.; Gattacceca, J.; Zander, T.; Eberhart, M.; Meindl, A.; Oefele, R.; Vaubaillon, J.; Colas, F.

2017-09-01

Recently and for the very first time, experiments simulating vaporization of a meteorite sample were performed in a wind tunnel near Stuttgart with the specific aim to record emission spectra of the vaporized material. Using a high enthalpy air plasma flow for modeling an equivalent air friction of an entry speed of about 10 km/s, three meteorite types (H, CM and HED) and two meteoritical analogues (basalt and argillite) were ablated and high resolution spectra were recorded simultaneously. After the identification of all atomic lines, we per- formed a detailed study of our spectra using two approaches: (i) by direct comparison of multiplet in- tensities between the samples and (ii) by computation of a synthetic spectrum to constrain some physical parameters (temperature, elemental abundance). Finally, we compared our results to the elemental composition of our samples and we determined how much compositional information can be retrieved for a given meteor using visible sectroscopy.

The Mesozoic rift basins of eastern North America: Potential reservoir or Explorationist's folly

Energy Technology Data Exchange (ETDEWEB)

Pyron, A.

1991-08-01

Mesozoic rift basins are found on the East Coast of North America from Georgia to Nova Scotia. The basins formed as a result of extensional activity associated with the breakup of Pangaea. The internal geometry of the basins includes a depositional sequence ranging from coarse fanglomerates to fine-grained siltstones and argillites. Since these Mesozoic rift basins were first studied, they have not been considered to be likely spots for hydrocarbon accumulations. Recently, geologists have reconsidered these Mesozoic basins and have developed a more synergistic approach that suggests that many of these rift basins might be suitable targets for exploration. By analogy, these Mesozoic basins are correlative to similar basins in northwestern Africa, where significant reserved of oil and natural gas have been developed. The similarity between the productive basins in northwestern Africa and the Mesozoic basins of North America and their proximity to major markets provides sufficient rationale to further investigate these basins.

Ways of increasing safety in mining at the Berezovskii-1 surface mine

Energy Technology Data Exchange (ETDEWEB)

Kuznetsov, N N; Malyarenko, V I

1986-12-01

Methods are descrubed wgucg were developed to alleviate or prevent the effects of landslides in a Kansk-Achinsk surface mine. Such a landslide took place in 1983 at the Berezovskii-1 mine when 250 m of an excavation trench suffered a collapse involving 680,000 mT of materials. Surveys revealed large zones of flooded ground with high proportions of argillites and aleurolites which swell in the presence of water. To keep costs down, a method using gravity is proposed for safety of re-excavation work near spoil banks. In this method a pillar of rock is left at the base of the spoil bank, the edge of the slope of which is moved back from the trench. Hard rock is placed at the leading edge of the spoil bank. The stability factor of the trench side may be raised from 0.87 to 1.12, and this is accompanied by savings in labor and costs.

Experience in landslide control

Energy Technology Data Exchange (ETDEWEB)

Koz' min, L S

1983-06-01

The problems of slope stability in the Krasnoyarskugol' surface mines are discussed. Methods used for slide prevention and slide control from 1977 to 1982 are analyzed. Landslides were caused by weathering of the argillite layer in the coal seam roof. Sliding plane was parallel to the coal seam roof. At a later stage of landslide prevention sliding planes were in the coal seam floor (which consisted of weak rock layers). Range of landslides was evaluated. Losses caused by landslides were discussed: working time losses, losses of coal, damaged equipment. Landslide hazards were controlled by reducing slope angle and by changing cut geometry. Cross section of the cut with a spoil bank prone to landslides is shown in a scheme. Reducing angle of slope inclination, using strong rock layers as the spoil bank base and changing cut geometry eliminated landslides in 1982. Recommendations on landslide control in coal surface mines with layers of weak rocks influenced by weathering are made.

Study of the strain's mechanism of deep argillaceous rocks: interest of microstructure and petro-physical analysis

International Nuclear Information System (INIS)

Gasc-Barbier, M.

2002-09-01

This study was carried out in order to better understand the behaviour of deep argillaceous rocks and in particular those chosen by ANDRA to build an underground laboratory to study the feasibility to set up an underground storage for highly radioactive wastes. We have studied experimentally different mechanisms (chemo-mechanical and hygro-mechanical coupling and creep behaviour) that could lead to macroscopic strain so as to attempt to characterize them from a microstructural point of view, Hence we have implemented innovative experimental tests such as the conception of a triaxial cell where fluids can circulate or the use of mercury porosimetry on dry or wet samples. We have thus been able to show the importance of the clay-calcite relation in the argillite studied both from the chemical point of view (chemical balance dominated by calcite) and from a structural point of view (micro-fissuration seems to take place preferentially at the grain / clayey material interface). (author)

Advice relative to the examination of the 'clay 2005 file'; Avis relatif a l'examen du 'dossier 2005 argile'

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-12-15

On request of the general director of the French nuclear safety and radiation protection institute (IRSN), the permanent group of experts for long duration waste disposal facilities has examined 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 group of experts has examined in particular the critical safety aspects of such a facility and the identification and consideration of uncertainties by the ANDRA in its safety analysis. It has also identified the main additional research works that may be carried out to demonstrate the feasibility of an industrial implementation of a safe disposal facility in the same Callovo-Oxfordian argilite formation. This document is the favourable advice and the recommendations expressed by the group of experts after examination of the ANDRA's 'clay 2005 file'. (J.S.)

Reconnaissance geologic map of the Dubakella Mountain 15 quadrangle, Trinity, Shasta, and Tehama Counties, California

Science.gov (United States)

Irwin, William P.; Yule, J. Douglas; Court, Bradford L.; Snoke, Arthur W.; Stern, Laura A.; Copeland, William B.

2011-01-01

The Dubakella Mountain 15' quadrangle is located just south of the Hayfork quadrangle and just east of the Pickett Peak quadrangle. It spans a sequence of four northwest-trending tectonostratigraphic terranes of the Klamath Mountains geologic province that includes, from east to west, the Eastern Hayfork, Western Hayfork, Rattlesnake Creek, and Western Jurassic terranes, as well as, in the southwest corner of the quadrangle, part of a fifth terrane, the Pickett Peak terrane of the Coast Ranges geologic province. The Eastern Hayfork terrane is a broken formation and melange of volcanic and sedimentary rocks that include blocks of limestone and chert. The limestone contains late Permian microfossils of Tethyan faunal affinity. The chert contains radiolarians of Mesozoic age, mostly Triassic, but none clearly Jurassic. The Western Hayfork terrane is an andesitic volcanic arc that consists mainly of agglomerate, tuff, argillite, and chert, and includes the Wildwood pluton. That pluton is related to the Middle Jurassic (about 170 Ma) Ironside Mountain batholith that is widely exposed farther north beyond the Dubakella Mountain quadrangle. The Rattlesnake Creek terrane is a highly disrupted ophiolitic melange of probable Late Triassic or Early Jurassic age. Although mainly ophiolitic, the melange includes blocks of plutonic rocks (about 200 Ma) of uncertain genetic relation. Some scattered areas of well-bedded mildly slaty detrital rocks of the melange appear similar to Galice Formation (unit Jg) and may be inliers of the nearby Western Jurassic terrane. The Western Jurassic terrane consists mainly of slaty to phyllitic argillite, graywacke, and stretched-pebble conglomerate and is correlative with the Late Jurassic Galice Formation of southwestern Oregon. The Pickett Peak terrane, the most westerly of the succession of terranes of the Dubakella Mountain quadrangle, is mostly fine-grained schist that includes the blueschist facies mineral lawsonite and is of Early

Geochemistry of the Oruatemanu Formation, Arrow Rocks, Northland, New Zealand

International Nuclear Information System (INIS)

Hori, R.S.; Higuchi, Y.; Fujiki, T.; Maeda, T.; Ikehara, M.

2007-01-01

We investigated the geochemical characteristics of sedimentary rocks from the Upper Permian - Middle Triassic Oruatemanu Formation on Arrow Rocks, Waipapa Terrane, New Zealand. The sedimentary rocks consist of limestone, tuffaceous shale, vari-coloured bedded chert, hemipelagic shale and green siliceous mudstone (= green argillite), in ascending order, a typical oceanic plate sequence. Shale and green argillite have higher Zr/Nb ratios than do chert and tuffaceous shales, and show similar REE patterns to PAAS (Post-Archean average Australian shale). In contrast, chert sequences from the basal part and intercalated tuff layers have high TiO 2 contents and Zr/Nb ratios similar to those of basaltic rocks from Arrow Rocks. These geochemical characteristics suggest that the sedimentary environment of the Oruatemanu Formation changed upward, from an open sea setting to the continental margin of Gondwanaland. Chemical compositions of bedded cherts from Arrow Rocks indicate a mixing of biogenic silica, detritus from continents and basaltic materials. In the interval from Upper Permian to Lower Middle Triassic this mixing shows remarkable secular variations. We detected geochemical signals of two Oceanic Anoxic Events (OAEs), one at the Permian/Triassic (P/T) boundary, and the other at the middle Upper Induan level. We name them the OAEα (P/T OAE) and OAEβ (Upper Induan OAE). These OAE horizons are enriched in S, U and other heavy metals (e.g. Mo and Cr), and also have high V/(V+Ni) ratios. Based on a comparison between enrichment factors of Cr and other redox-sensitive trace elements (e.g. Zn, Pb, Co, Cu), the Upper Induan OAEβ is considered to be more intense than the P/T boundary OAEα. This result is not in agreement with the superanoxia model previously proposed. In addition, OAEβ corresponds well with the radiolarian faunal turnover from Permian to Triassic forms documented from the Oruatemanu Formation in this volume. These results may suggest that peak time and

Geology of Glacier National Park and the Flathead Region, Northwestern Montana

Science.gov (United States)

Ross, Clyde P.

1959-01-01

introduces complexities into stratigraphic correlation and should be remembered wherever the series is studied. The stromatolites, or fossil algae, in the Belt series, although still imperfectly understood, give clues with respect to problems of ecology and stratigraphy. The subdivisions of the Belt series within the areas covered by the present report are, in ascending order, Altyn limestone, Appekunny argillite, Grinnell argillite, Siyeh limestone, and Missoula group. Local subdivisions of the Missoula group are possible in certain areas, and all the units just named are expected to be subdivided when detailed studies are undertaken. In the Glacier National Park and Flathead regions together, it is probable that between 25,000 and 30,000 feet of beds belonging to the Belt series, possibly more, are present. These consist largely of quartzitic argillite, quartzite, and carbonate rocks, mostly dolomitic. Small gabbroic and diabasic intrusive bodies and, at one horizon, basaltic lava are associated with the Belt series. Above the Belt series is a thick sequence of Cambrian, Devonian, and Carboniferous strata, in which limestone is dominant, followed by strata of Jurassic and Cretaceous age, largely limestone and shale and partly of terrestrial origin. Slightly consolidated gravel, sand, and silt of Tertiary age are preserved in some valleys and as erosional remnants on the plains close to the mountain border. Pleistocene and Recent glacial and fluviatile deposits are plentiful in mountain valleys and on the plains east of the mountains. Sufficient crustal movements took place during the latter part of Belt time to produce tension cracks that permitted some intrusion and related extrusion to occur. Broad crustal warping probably took place at intervals during the Paleozoic era, but these successive movements left little record other than the absence of sedimentary rock units that might otherwise have been deposited. The same can be said of much of the Me

Influence of temperature on the geochemistry of Callovo-Oxfordian argillite: batch experiments and modelling at 80 deg. C

International Nuclear Information System (INIS)

Gailhanou, H.; Tournassat, C.; Laperche, V.; Grangeon, S.; Blanc, P.; Marty, N.; Crouzet, C.; Henry, B.; Gaucher, E.C.; Greneche, J.M.; Kars, M.; Made, B.; Altmann, S.

2012-01-01

Document available in extended abstract form only. A repository of high-level nuclear wastes in the Callovo-Oxfordian (COx) clay rock will lead to a temporary increase in temperature locally around the disposal cells, up to about 80 C. Thermally induced modifications of the pore-water chemistry of the clay rock must be assessed since the pore water chemistry can affect the rates of corrosion of metallic materials used in the disposal facility. The chemistry of COx pore water has been studied at ambient temperature (∼ 25 C) using modelling approaches constrained by parameter values measured on core samples and by measurements of pore water collected by means of specially designed in-situ experiments. In particular, the predictive model from Gaucher et al. (2009) reproduces the measured, in situ pore-water composition without any estimated parameters. In the present study, carried out as part of a collaborative BRGM/Andra research program, the results of long-term batch experiments performed at 80 C, are compared with compositions predicted using a model based on the one developed for 25 C. Batch experiments Two batch experiments have been performed with COx rock samples in contact with synthetic water, for respectively 6 and 20 months. The experiments were prepared at 25 C under anoxic atmosphere in closed reactors, with solution compositions close to the pore water composition. Afterwards, each system was heated at 80 C. During the experiments, measurements of PCO 2 were carried out as this parameter is considered as an indicator of the reactivity of this carbonate-dominated system. At the end of the experiments, the suspension was filtered at 0.1 μm at 80 C, under anoxic atmosphere. The pH was also measured at 80 C. Major cations (Ca, Mg, K, Na, Sr) and anions (notably Cl, SO 4 ), TIC and minor and trace elements (notably Si, Al, Fe, Zn, Pb) were analysed. Concerning the solids, some minor changes were detected in the mineralogy between initial and final solids, essentially partial dissolution of celestite and a small increase in the amount of dolomite. Besides, an interesting change was observed by TEM with the formation of needles of nanocrystalline goethite on pyrite particles for the solid from the 20 months experiment. Such needles were not observed on the initial solid, although magnetic measurements at low temperature on the sample revealed the presence of nanocrystalline goethite. Moreover, an increasing of the Fe 2+ /Fe 3+ ratio in the octahedral environment of clay minerals, compared with initial ratio, was evidenced by 57 Fe Moessbauer spectrometry. Modelling of batch experiments The predictive model of composition as a function of temperature was developed, based on the Gaucher et al. (2009) model and using the PHREEQC code and Thermoddem database. As a first approximation, the model considers a primary mineral assemblage with quartz, pyrite, carbonates (calcite, dolomite and siderite), sulfates (celestite), aluminosilicates (chlorite and illite). Moreover, the model takes into account exchange reactions and dissolution reaction kinetics for the potentially more reactive minerals. For both cases, at 6 and 20 months, the comparison between estimated and observed concentrations of ions in solution are in rather good agreement for pH, Si, Al, major cations (Ca, Mg, Na, K, Sr) and for sulphates and chlorides. The calculated concentrations of Fe are, on the other hand, too high compared with the measured concentrations, for both experiments. The control on the Fe(II) solubility by siderite was already questioned in Gaucher et al. (2009). This problem is being studied, notably by considering the presence of nano-goethite detected in the initial sample and in the solid after 20 months experiment

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)

Bretaudeau, Francois; Gelis, Celine; Cabrera, Justo; Leparoux, Donatienne; Cote, Philippe

2012-01-01

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

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.

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

International Nuclear Information System (INIS)

Rousseau-gueutin, P.

2008-09-01

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

Some micromechanical models of elastoplastic behaviors of porous geomaterials

Directory of Open Access Journals (Sweden)

W.Q. Shen

2017-02-01

Full Text Available Some micromechanics-based constitutive models are presented in this study for porous geomaterials. These micro-macro mechanical models focus on the effect of porosity and the inclusions on the macroscopic elastoplastic behaviors of porous materials. In order to consider the effect of pores and the compressibility of the matrix, some macroscopic criteria are presented firstly for ductile porous medium having one population of pores with different types of matrix (von Mises, Green type, Mises–Schleicher and Drucker–Prager. Based on different homogenization techniques, these models are extended to the double porous materials with two populations of pores at different scales and a Drucker–Prager solid phase at the microscale. Based on these macroscopic criteria, complete constitutive models are formulated and implemented to describe the overall responses of typical porous geomaterials (sandstone, porous chalk and argillite. Comparisons between the numerical predictions and experimental data with different confining pressures or different mineralogical composites show the capabilities of these micromechanics-based models, which take into account the effects of microstructure on the macroscopic behavior and significantly improve the phenomenological ones.

Present exploration status of the Lianshanguan uranium deposit, Northeast China

International Nuclear Information System (INIS)

Fei, Q.; Shaokang, H.

1980-01-01

During recent years surface radiometry has revealed a series of anomalies and uranium occurrences in the Lianshanguan region of Northeast China which are present in Proterozoic Formations. Several significant uranium occurrences were tested by trenching and core drilling which resulted in the discovery of the Lianshanguan uranium deposit in 1978. The ore bodies of economic significance are located at a depth of 38-250m. Potential reserves are 1000 tons of U 3 O 8 . The geological setting of the Lower Proterozoic Lianshanguan uranium deposit has a certain similarity to the Alligator Rivers Region, Northern Territory, Australia. However, the Lianshanguan deposit occurs in detrital formations (in the lower part of the Lower Proterozoic sequence), adjacent to a migmatitic zone; it is overlain by carbonate argillitic rocks. The discovery of the Lianshanguan deposit indicates a potential for further uranium discoveries in northeast China, where Proterozoic sequences are well developed. The Lianshanguan uranium deposit is located approximately 100km south of Shenyang at 40 0 59'N and 123 0 30'E

Rate of driving a ventilation tunnel by means of the GPK heading machine using roof bolting and steel supports. [USSR

Energy Technology Data Exchange (ETDEWEB)

Cheremnov, V.I.; Kruglyak, A.S.; Miroshnikova, L.A.; Sharov, V.N.

1983-05-01

The paper discusses a method for strata control during mine drivage tested in the im. Voroshilov coal mine in 1982. A ventilation tunnel with a crosscut of 16.4 m/sup 2/ was driven in coal with compression strength coefficient from 0.8 to 1.0, argillites and aleurites in the floor and the roof with compression strength coefficient from 4 to 6. Mining depth was 150 m, water influx was low. The tunnel was driven by means of the GPK heading machine with a 1PNB-2 loader. The AMK support system which consisted of arched steel supports, steel beams for joining steel arches and of roof bolts was used. Arched supports were installed each 0.8 m. The roof between the arches was supported by a system of roof bolts and junction beams. Support design is shown in a scheme. Increasing support spacing to 0.8 m (instead of 0.5 m) and roof bolting permitted drivage rate to be increased and steel consumption to be significantly reduced (by 244 kg/m). (3 refs.)

Deep disposal of high activity radioactive wastes: the study of engineered and geological barriers behaviour

International Nuclear Information System (INIS)

Yu Jun; Cui; Delage, P.; Laure, E. de; Behrouz, Gatmiri; Sulem, J.; Anh Minh, Tang

2008-09-01

One option for the isolation of high activity and long lived radioactive wastes is the disposal of the vitrified waste containers in galleries dug inside impermeable rocks of the deep underground (granite, argillite, salt). The multi-barrier isolation concept is based on the use of successive barriers to avoid the migration of radionuclides towards the biosphere (container envelope, engineered barrier made of compacted swelling clay, and host rock). In parallel to the works carried out in underground laboratories, experiments and simulation works are performed in order to understand the behaviour of storage facilities and barriers under the effects of constraints, water fluxes and temperature changes. In this context, the UR Navier geotechnical team (CERMES), a joint research unit of Ecole des Ponts ParisTech and LCPC, has been working for more than 15 years on this topic for various contractors. These works are based on original experimental devices allowing to identify the thermo-hydro-mechanical phenomena and thereafter to model them. This dossier presents a summary of these works. (J.S.)

New Experimental Approach for Studying Diffusion through an Intact and Unsaturated Medium: A Case Study with Callovo-Oxfordian Argillite

International Nuclear Information System (INIS)

Savoye, S.; Puente, C.; Coelho, D.; Imbert, Ch.; Page, J.

2010-01-01

The diffusion of tritiated water and anionic species was studied in an unsaturated core of Callovo-Oxfordian clay-stone, which is a potential host-rock for disposal of high-level radioactive wastes. The diffusion parameters in such conditions were determined using modified through-diffusion cells in which the suction is generated by the osmosis process. This specific device leads to values of saturation degree ranging from 81% to 100%. The results show that the diffusion through unsaturated samples is clearly slower than that in fully saturated samples, with steady-state fluxes decreasing by a factor up to 7 for tritium and up to 50 for anionic species. While tritium porosity values follow volumetric water contents (from 21 to 16%), the porosity accessible to anionic species significantly decreases (from 7. 5 to 0. 7%). Such diffusive behaviors have been modeled by means of a modified Archie's law, taking into account a critical water saturation below which no tracer can percolate. These results indicate that the largest pores, which are initially affected by dehydration, would play an important role on the connectivity of the porous medium. This would especially affect anionic species diffusion behavior because they are constrained to diffuse into the largest pores first. (authors)

Iodide behaviour in hard clay rocks under controlled physico-chemical conditions at different concentrations

International Nuclear Information System (INIS)

Frasca, B.; Savoye, S.; Wittebroodt, C.; Leupin, O.X.; Descostes, M.; Grenut, B.; Meier, P.; Michelot, J.L.

2010-01-01

Document available in extended abstract form only. With a half-life of 1.6 10 7 years, its high mobility and its potential to accumulate in the biosphere, iodine-129 is considered, from safety assessment calculations for radioactive waste repositories, to be one of the main radiological dose contributors. Based on the findings of previous studies, iodide, especially at low concentrations, seems to be migrating at a slower rate in clay rock than Cl-36. The cause of this retardation regarding the diffusion of iodide versus chloride is not yet understood but several hypotheses are point towards sorption on natural organic matter (NOM), pyrite or redox reactions. Oxidation of iodide would form IO 3 - which is known to have a higher sorption affinity on several soils and sediment samples than iodide. The present project aims at exploring the effect on the iodide behaviour of two parameters: (i) the initial concentration of iodide and (ii) the amount of NOM contained in the argillite samples. Such an investigation is carried out on Tournemire argillite by means of both batch and through-diffusion experiments. The main challenge is to exclude as much as possible the occurrence of any experimental artefact that could induce iodide uptake (oxygen contamination, dissolution/precipitation of carbonate phases). Regarding redox conditions and rock equilibrium, all the experiments were carried out under physico-chemical conditions as close as possible to those prevailing in field. Using a glove box with an atmosphere of N 2 /CO 2 (respectively 99.6% and 0.4%), we preserved the experiments from oxygen and maintained the calculated in-situ carbonate equilibrium. At first, four through-diffusion experiments with the non-sorbing tracers HTO and Cl-36 were performed to allow the diffusive parameters of each sample to be defined. Afterwards, iodide was injected in the diffusion cells at four different concentrations (10 -6 M to 10 -3 M). Thus, the comparison of the incoming fluxes of

Review of potential host rocks for radioactive wasste disposal in the southeast United States: Triassic basin subregion

International Nuclear Information System (INIS)

1980-10-01

Based on an evaluation of existing information, areas were identified within the Triassic basins of the southeastern United States with geologic properties considered favorable for containment of radioactive waste. The study region included both exposed and buried Triassic basins from Maryland to Georgia. These basins are long, narrow northeast-trending troughs filled with continental deposits derived from Paleozoic and Precambrian metamorphic and igneous rocks bordering the basins. The rocks are predominantly red in color and consist mainly of fanglomerates, conglomerates, arkosic sandstones, siltstones, claystones, shales, and argillites. The investigation identified 14 exposed and 5 buried basins within the study region. Candidate areas for further investigation were identified which meet the broad general criteria for tectonic stability, slow ground water movement, and long flow paths to the biosphere. These include: the Danville Triassic Basin in Virginia; the Dan River, Durham, and Wadesboro Triassic Basins in North Carolina; and the buried Florence and Dunbarton Triassic Basins in South Carolina. Other rock types in the southeast may prove more or less suitable as host rocks for a repository, but the available data suggest that the argillaceous Triassic rocks offer sufficient promise to be considered for additional study

Disposal of high level and long lived radioactive waste in deep geological formation

International Nuclear Information System (INIS)

Niezborala, J.M.; Hoorelbeke, J.M.

2000-01-01

The status of ANDRA's research program on high level and long lived waste corresponds to the start of construction of the Meuse/Haute-Marne Underground Research Laboratory in an argillite layer, as well as to the selection in 1999 of preliminary disposal concepts corresponding to this layer. The paper describes the preliminary concepts dealing with transuranic waste, high level vitrified waste and potentially disposed spent fuel. Provision is made for a high level of flexibility, in particular with regard to options of reversibility of the disposal process, and to potential evolutions of the waste inventory. These concepts were selected for research purpose to assess by the year 2006 the feasibility of a potential repository, with.respect in particular to safety rules. The paper mentions the research targets of the program aiming at answering major scientific and technological questions raised by the concepts. The program includes the fitting and validation of the modelling, on the basis in particular of the experimental work to be carried out in the Underground Research Laboratory, making it possible to dimension the disposal concepts and to assess their safety. (authors)

Preliminary rate expressions for analysis of radionuclide migration resulting from fluid flow through jointed media

Energy Technology Data Exchange (ETDEWEB)

Erickson, K.L.

1979-01-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and tertiary silicic tuffs in contact with solutions containing Cs, Sr, or Pm indicated that most radionuclide sorption was associated with the surfaces of very small intergranular regions and that the rate of sorption was controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity and sorption distribution coefficient. Many of these parameters represent physical quantities or processes which can be quantified in the laboratory. However, fluid velocities and fracture plate spacings and lengths must be obtained from the field, and methods must be developed to establish reliable bounds for such field-determined parameters.

Preliminary rate expressions for analysis of radionuclide migration resulting from fluid flow through jointed media

International Nuclear Information System (INIS)

Erickson, K.L.

1979-01-01

A theoretical and experimental basis is being developed for analysis of radionuclide transport in jointed geologic media. Batch equilibration and rate experiments involving samples of Eleana argillite and tertiary silicic tuffs in contact with solutions containing Cs, Sr, or Pm indicated that most radionuclide sorption was associated with the surfaces of very small intergranular regions and that the rate of sorption was controlled by diffusion of the nuclides into such regions. Based on these experimental results, the continuity equations for radionuclides in the mobile and immobile phases were reduced to a model analogous to Rosen's equations for packed beds and were solved similarly. Using the model and experimental data, limited radionuclide transport analyses were made which indicated that important parameters controlling transport include the intergranular porosity and nuclide penetration depth, fracture plate spacing and length, fluid velocity and sorption distribution coefficient. Many of these parameters represent physical quantities or processes which can be quantified in the laboratory. However, fluid velocities and fracture plate spacings and lengths must be obtained from the field, and methods must be developed to establish reliable bounds for such field-determined parameters

Indian program on management of high level radioactive waste - emphasis on value recovery for societal applications

International Nuclear Information System (INIS)

Kaushik, C.P.; Tomar, Neelima Singh; Kumar, Amar; Wadhwa, S.; Diwan, Jyoti

2017-01-01

Nuclear Power Programme in India is based on 'closed fuel cycle'. Closed fuel cycle involves reprocessing and recycling of Spent Nuclear Fuel (SNF) coming out of nuclear reactors. During reprocessing, uranium and plutonium, constituting bulk of the SNF are separated and subsequently recycled. The remaining small portion constitutes high level radioactive waste containing most of the fission products and minor actinides. A three-step strategy involving immobilization, interim storage followed by ultimate disposal has been adopted in India for management of High Level Waste (HLW). Borosilicate glass matrix has been identified for immobilization of HLW owing to optimal waste loading, adequate leach resistance and long term stability of the product. An interim storage facility is in operation for storage and surveillance of VWP. A comprehensive program based on screening of different materials like granite, argillite, clay with respect to sorption of different radionuclides is being pursued to identify the suitable areas of disposal of the conditioned waste products. Separation of useful radionuclides like "1"3"7Cs, "9"0Sr, "9"0Y, "1"0"6Ru etc and its utilization for societal applications is being practiced in India. (author)

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

International Nuclear Information System (INIS)

Langenheim, V.E.; Ponce, D.A.

1995-01-01

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

Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model

Directory of Open Access Journals (Sweden)

Aliaksei Pazdniakou

2018-01-01

Full Text Available Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.

Multiple sources of selenium in ancient seafloor hydrothermal systems: Compositional and Se, S, and Pb isotopic evidence from volcanic-hosted and volcanic-sediment-hosted massive sulfide deposits of the Finlayson Lake District, Yukon, Canada

Science.gov (United States)

Layton-Matthews, Daniel; Leybourne, Matthew I.; Peter, Jan M.; Scott, Steven D.; Cousens, Brian; Eglington, Bruce M.

2013-09-01

Volcanic-hosted massive sulfide (VHMS) and volcanic-sediment-hosted massive sulfide (VSHMS; i.e., hosted by both volcanic and sedimentary rocks) deposits in the Finlayson Lake District, Yukon, Canada, provide a unique opportunity to study the influence of seafloor and sub-seafloor hydrothermal processes on the formation of Se-poor (GP4F VHMS deposit; 7 ppm Se average), intermediate (Kudz Ze Kayah—KZK VHMS deposit; 200 ppm Se average), and Se-enriched (Wolverine VSHMS deposit; 1100 ppm Se average) mineralization. All three deposits are hosted by mid-Paleozoic (˜360-346 Ma) felsic volcanic rocks, but only the Wolverine deposit has voluminous coeval carbonaceous argillites (black shales) in the host rock package. Here we report the first application of Se isotope analyses to ancient seafloor mineralization and use these data, in conjunction with Pb and S isotope analyses, to better understand the source(s) and depositional process(es) of Se within VHMS and VSHMS systems. The wide range of δ82Se (-10.2‰ to 1.3‰, relative to NIST 3149), δ34S (+2.0‰ to +12.8‰ CDT), and elevated Se contents (up to 5865 ppm) within the Wolverine deposit contrast with the narrower range of δ82Se (-3.8‰ to -0.5‰), δ34S (9.8‰ to 13.0‰), and lower Se contents (200 ppm average) of the KZK deposit. The Wolverine and KZK deposits have similar sulfide depositional histories (i.e., deposition at the seafloor, with concomitant zone refining). The Se in the KZK deposit is magmatic (leaching or degassing) in origin, whereas the Wolverine deposit requires an additional large isotopically negative Se source (i.e. ˜-15‰ δ82Se). The negative δ82Se values for the Wolverine deposit are at the extreme light end for measured terrestrial samples, and the lightest observed for hypogene sulfide minerals, but are within calculated equilibrium values of δ82Se relative to NIST 3149 (˜30‰ at 25 °C between SeO4 and Se2-). We propose that the most negative Se isotope values at the

In situ determination of anisotropic permeability of clay

International Nuclear Information System (INIS)

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

2011-01-01

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

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.

Integration of spectral, spatial and morphometric data into lithological mapping: A comparison of different Machine Learning Algorithms in the Kurdistan Region, NE Iraq

Science.gov (United States)

Othman, Arsalan A.; Gloaguen, Richard

2017-09-01

Lithological mapping in mountainous regions is often impeded by limited accessibility due to relief. This study aims to evaluate (1) the performance of different supervised classification approaches using remote sensing data and (2) the use of additional information such as geomorphology. We exemplify the methodology in the Bardi-Zard area in NE Iraq, a part of the Zagros Fold - Thrust Belt, known for its chromite deposits. We highlighted the improvement of remote sensing geological classification by integrating geomorphic features and spatial information in the classification scheme. We performed a Maximum Likelihood (ML) classification method besides two Machine Learning Algorithms (MLA): Support Vector Machine (SVM) and Random Forest (RF) to allow the joint use of geomorphic features, Band Ratio (BR), Principal Component Analysis (PCA), spatial information (spatial coordinates) and multispectral data of the Advanced Space-borne Thermal Emission and Reflection radiometer (ASTER) satellite. The RF algorithm showed reliable results and discriminated serpentinite, talus and terrace deposits, red argillites with conglomerates and limestone, limy conglomerates and limestone conglomerates, tuffites interbedded with basic lavas, limestone and Metamorphosed limestone and reddish green shales. The best overall accuracy (∼80%) was achieved by Random Forest (RF) algorithms in the majority of the sixteen tested combination datasets.

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

International Nuclear Information System (INIS)

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

Isotopic (U-Pb, Nd) and geochemical constraints on the origins of the Aileu and Gondwana sequences of Timor

Science.gov (United States)

Boger, S. D.; Spelbrink, L. G.; Lee, R. I.; Sandiford, M.; Maas, R.; Woodhead, J. D.

2017-02-01

Detrital zircon U-Pb age data collected from the argillitic sedimentary rocks of the Timorese Aileu Complex and Gondwana Sequence indicate that both units were derived from a common source containing 200-600 Ma, 900-1250 Ma and 1450-1900 Ma zircon. The modally most significant age population within this range of ages dates to c. 260 Ma. The observed spectrum of ages can be traced to the eastern active margin of Pangaea and its immediate foreland, which today is best exposed along the northeast coast of Australia. Compared to the relative homogeneity of the detrital zircon age data, geochemical and Nd isotopic data show that the mudstones of the Aileu Complex are on average more siliceous, have higher K2O/Na2O, Rb/Sr, Th/Sc and yield notably older Nd TDM model ages when compared to those from the Gondwana Sequence. These data are interpreted to suggest that, although both sequences share a common east Pangaea provenance, they were eroded from different sections of this active margin and deposited in spatially separated basins. The present proximity of these units is a result of their tectonic juxtaposition during the Pliocene to Recent collision between the northern edge of the Indo-Australia plate and the Banda Arc.

Clay Generic Disposal System Model - Sensitivity Analysis for 32 PWR Assembly Canisters (+2 associated model files).

Energy Technology Data Exchange (ETDEWEB)

Morris, Edgar [Argonne National Lab. (ANL), Argonne, IL (United States)

2014-10-01

The Used Fuel Disposition Campaign (UFDC), as part of the DOE Office of Nuclear Energy’s (DOE-NE) Fuel Cycle Technology program (FCT) is investigating the disposal of high level radioactive waste (HLW) and spent nuclear fuela (SNF) in a variety of geologic media. The feasibility of disposing SNF and HLW in clay media has been investigated and has been shown to be promising [Ref. 1]. In addition the disposal of these wastes in clay media is being investigated in Belgium, France, and Switzerland. Thus, Argillaceous media is one of the environments being considered by UFDC. As identified by researchers at Sandia National Laboratory, potentially suitable formations that may exist in the U.S. include mudstone, clay, shale, and argillite formations [Ref. 1]. These formations encompass a broad range of material properties. In this report, reference to clay media is intended to cover the full range of material properties. This report presents the status of the development of a simulation model for evaluating the performance of generic clay media. The clay Generic Disposal System Model (GDSM) repository performance simulation tool has been developed with the flexibility to evaluate not only different properties, but different waste streams/forms and different repository designs and engineered barrier configurations/ materials that could be used to dispose of these wastes.

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

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

International Nuclear Information System (INIS)

Vi-Nhu-Ba, Elise

2014-01-01

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)

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

International Nuclear Information System (INIS)

Viggiani, Gioacchino; Besuelle, Pierre; Desrues, Jacques

2013-01-01

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)

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

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Montarges-Pelletier, E.; Michot, L.; Villieras, F.; Abdelmoula, M.; Karunakaran, C.; Ventelon, D.; Michau, N.

2010-01-01

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 , CaCl 2 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

Multivariate and spatial statistical analysis of Callovo-Oxfordian physical properties from lab and borehole logs data: towards a characterization of lateral and vertical spatial trends in the Meuse/Haute-Marne transposition zone

International Nuclear Information System (INIS)

Garcia, M.H.; Rabaute, A.; Yven, B.; Guillemot, D.

2010-01-01

Document available in extended abstract form only. The geological exploration of the Meuse/Haute-Marne area began in 1994. Several boreholes were drilled, and the Callovo-Oxfordian argillite, thought to become a potential storage formation, were cored and logged. 2D and 3D seismic surveys were completed, as well as geological field observations, and an underground research laboratory was created. A 250 km 2 -wide Transposition Zone was delimited, which was subject to further investigations in 2007 and 2008, including another series of coring and logging in four additional boreholes, and a tighter 2D seismic survey. The main objective of this study was to improve the knowledge of the spatial variability of geological and physical properties of the Callovo-Oxfordian formation. The paper focuses on the three following aspects of the study to present and discuss the methods that have been used and the results that have been obtained: - Use of well-log data to identify equivalent homogeneous log-units on the boreholes. - Relating log attributes to physical properties of argillites measured on cores in laboratory. - Study of lateral and vertical spatial trends of selected physical properties across the Transposition Zone (TZ). To identify equivalent homogeneous log-units, a combination of Principal Component Analysis (PCA) and Fuzzy Cluster Analysis (FCA) was used. PCA was classically performed to reduce the number of variables to retain principal components gathering most of the original dataset variance. PCA was also used to identify isolated groups of correlated variables that could be associated to different properties of the formation. Then, FCA was applied to identify homogeneous log-units on the eight boreholes across the TZ. Well-logs data being much more numerous and better distributed along boreholes than lab data measured on rock samples, relations and correlations were sought between the two types of data to identify log attributes that were likely to provide

Geologic history of the Blackbird Co-Cu district in the Lemhi subbasin of the Belt-Purcell Basin

Science.gov (United States)

Bookstrom, Arthur A.; Box, Stephen E.; Cossette, Pamela M.; Frost, Thomas P.; Gillerman, Virginia; King, George; Zirakparvar, N. Alex

2016-01-01

The Blackbird cobalt-copper (Co-Cu) district in the Salmon River Mountains of east-central Idaho occupies the central part of the Idaho cobalt belt—a northwest-elongate, 55-km-long belt of Co-Cu occurrences, hosted in grayish siliciclastic metasedimentary strata of the Lemhi subbasin (of the Mesoproterozoic Belt-Purcell Basin). The Blackbird district contains at least eight stratabound ore zones and many discordant lodes, mostly in the upper part of the banded siltite unit of the Apple Creek Formation of Yellow Lake, which generally consists of interbedded siltite and argillite. In the Blackbird mine area, argillite beds in six stratigraphic intervals are altered to biotitite containing over 75 vol% of greenish hydrothermal biotite, which is preferentially mineralized.Past production and currently estimated resources of the Blackbird district total ~17 Mt of ore, averaging 0.74% Co, 1.4% Cu, and 1.0 ppm Au (not including downdip projections of ore zones that are open downward). A compilation of relative-age relationships and isotopic age determinations indicates that most cobalt mineralization occurred in Mesoproterozoic time, whereas most copper mineralization occurred in Cretaceous time.Mesoproterozoic cobaltite mineralization accompanied and followed dynamothermal metamorphism and bimodal plutonism during the Middle Mesoproterozoic East Kootenay orogeny (ca. 1379–1325 Ma), and also accompanied Grenvilleage (Late Mesoproterozoic) thermal metamorphism (ca. 1200–1000 Ma). Stratabound cobaltite-biotite ore zones typically contain cobaltite1 in a matrix of biotitite ± tourmaline ± minor xenotime (ca. 1370–1320 Ma) ± minor chalcopyrite ± sparse allanite ± sparse microscopic native gold in cobaltite. Such cobaltite-biotite lodes are locally folded into tight F2 folds with axial-planar S2 cleavage and schistosity. Discordant replacement-style lodes of cobaltite2-biotite ore ± xenotime2 (ca. 1320–1270 Ma) commonly follow S2fractures and fabrics

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)

Lassin, A.; Dymitrowska, M.; Azaroual, M.

2011-01-01

In nuclear waste geological disposals, large amounts of hydrogen (H 2 ) are expected to be produced by different (bio-)geochemical processes. Depending on the pressure generated by such a process, H 2 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 H 2 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)

Characteristics of the streak clays of the hyacinth gold deposit by the techniques of DRX and AT

International Nuclear Information System (INIS)

Trueba Gaetano, R.; Cabrera Diaz, I.; Casanova Gomez, A.; Aguila Terry, A.; Martinez Montalvo, A.; Canel Carreras, L.; Rodriguez Garcia, J. C.; Alonso Perez, J. A.

2016-01-01

It is exposed the investigative work of the mineralogical characteristics of different types of clays present in the veins of the Oro Jacinto deposit through the use of XRD and TA analytical techniques, supported by a study of particle size in the range of 2 mm to 63 μm. Significant feature of these samples is that being crushed they generated high content of fine material below 0.074 mm. This size particles range is presented between 17.68% and 50.78% of samples volume, majority particles being smaller than 0.063 mm, this interstratificated fine material with different types of clay makes the fraction below 74 μm present characteristics of clayey material. The results of XRD analysis and comparative Thermo gravimetric that are achieved for samples of 'Jacinto' gold vein deposit indicate that the clays presented in the fine fractions are: chlorite-montmorillonite; illite; hidromoscovite and muscovite, which turned out to be higher in samples of the grain B eatriz . During the ores formation process of the veins S ur Elena , it is evident that the hydrothermal fluids that led to the formation of the rocks, experienced greater degree of alteration during its transformation into argillite, which is manifested in three mineralogical regularities: Low crystallinity of the chlorite-montmorillonite clay. Transformation of muscovite - hidromoscovite into illite. Presence of abundant calcite in some samples. Higher concentrations of iron oxides (goethite). (Author)

M4FT-16LL080303052-State of Knowledge for Colloid Facilitated Radionuclide Transport and Update on Actinide Diffusion in Bentonite Backfill

Energy Technology Data Exchange (ETDEWEB)

Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.. Physical and Life Sciences; Joseph, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.. Physical and Life Sciences

2016-08-16

This progress report (Level 4 Milestone Number M4FT-16LL080303052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Crystalline Disposal R&D Activity Number FT-16LL080303051 and Crystalline International Collaborations Activity Number FT-16LL080303061. The focus of this research is the interaction of radionuclides with Engineered Barrier System (EBS) and host rock materials at various physico-chemical conditions relevant to subsurface repository environments. They include both chemical and physical processes such as solubility, sorption, and diffusion. The colloid-facilitated transport effort focused on preparation of a draft manuscript summarizing the state of knowledge and parameterization of colloid-facilitated transport mechanisms in support of reactive transport and performance assessment models for generic crystalline repositories. This draft manuscript is being submitted as a level 3 milestone with LANL as the primary author. LLNL’s contribution to that effort is summarized only briefly in the present report. A manuscript summarizing long-term U(VI) diffusion experiments through bentonite backfill material was recently accepted for publication; the contents of that manuscript are summarized in the present report. The Np(IV) diffusion experiments were started mid-year and are ongoing. The completion of these experiments is planned for early FY17. Our progress in quantifying Np(IV) diffusion in bentonite backfill is summarized in the present report. Our involvement with the NEA TDB project was summarized in a recent Argillite Disposal activity report. It is not included in this report.

Successive hydrothermal events as indicated by oxygen isotope composition and petrography of greywacke basement rocks, Kawerau geothermal field, New Zealand

International Nuclear Information System (INIS)

Absar, A.; Blattner, P.

1985-01-01

Fifteen drillholes at the Kawerau geothermal field penetrated a sequence of Quaternary volcanic rocks overlying Mesozoic greywackes and argillites in the depth range of 650 to 1220 m below sea level. Maximum temperature in the basement is 250 to 303 deg. C. Twelve greywacke cores were modally analysed in order to determine their intensity of alteration, which in turn was compared with their oxygen isotope composition. It is concluded that Kawerau geothermal field has experienced at least three hydrothermal regimes. The earliest was characterised by fluids with low m CO 2 and δ 18 O, as indicated by the wairakite-prehnite mineral assemblage in greywacke depleted by 5 ppm. This regime was followed by a period of hydraulic fracturing the formation of a mineral assemblage with abundant calcite indicative of fluids with high dissolved CO 2 . Precipitation of minerals during these two early successive hydrothermal regimes resulted in sealing of fractures in the southern part of the field. These two mineral assemblages are indicated to have formed prior to faulting. The latest mineral assemblage comprising quartz-calcite-adularia-calc silicates on the other hand, is related to a series of NE trending faults which enabled geothermal fluids to move northeastward after circulation was precluded in the southern part. This suggests that future exploration for production from the greywacke basement should be in the north where mineralogy and δ 18 O composition of calcite indicate that much better permeability occurs

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

Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

International Nuclear Information System (INIS)

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

2010-01-01

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

The Cannery Formation--Devonian to Early Permian arc-marginal deposits within the Alexander Terrane, Southeastern Alaska

Science.gov (United States)

Karl, Susan M.; Layer, Paul W.; Harris, Anita G.; Haeussler, Peter J.; Murchey, Benita L.

2011-01-01

cherts on both Admiralty and Kupreanof Islands contain radiolarians as young as Permian, the age of the Cannery Formation is herein extended to Late Devonian through early Permian, to include the early Permian rocks exposed in its type locality. The Cannery Formation is folded and faulted, and its stratigraphic thickness is unknown but inferred to be several hundred meters. The Cannery Formation represents an extended period of marine deposition in moderately deep water, with slow rates of deposition and limited clastic input during Devonian through Pennsylvanian time and increasing argillaceous, volcaniclastic, and bioclastic input during the Permian. The Cannery Formation comprises upper Paleozoic rocks in the Alexander terrane of southeastern Alaska. In the pre-Permian upper Paleozoic, the tectonic setting of the Alexander terrane consisted of two or more evolved oceanic arcs. The lower Permian section is represented by a distinctive suite of rocks in the Alexander terrane, which includes sedimentary and volcanic rocks containing early Permian fossils, metamorphosed rocks with early Permian cooling ages, and intrusive rocks with early Permian cooling ages, that form discrete northwest-trending belts. After restoration of 180 km of dextral displacement of the Chilkat-Chichagof block on the Chatham Strait Fault, these belts consist, from northeast to southwest, of (1) bedded chert, siliceous argillite, volcaniclastic turbidites, pillow basalt, and limestone of the Cannery Formation and the Porcupine Slate of Gilbert and others (1987); (2) greenschist-facies Paleozoic metasedimentary and metavolcanic rocks that have Permian cooling ages; (3) silty limestone and calcareous argillite interbedded with pillow basalt and volcaniclastic rocks of the Halleck Formation and the William Henry Bay area; and (4) intermediate-composition and syenitic plutons. These belts correspond to components of an accretionary complex, contemporary metamorphic rocks, forearc-basin deposits,

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

Energy Technology Data Exchange (ETDEWEB)

Goutelard, F.; Charles, Y.; Page, J. [CEA/DEN/DPC/SECR/L3MR batiment 450, 91191 Gif sur Yvette (France)

2005-07-01

}Ni are used to quantify the 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 cm{sup 2}) 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)

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

International Nuclear Information System (INIS)

Goutelard, F.; Charles, Y.; Page, J.

2005-01-01

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 cm 2 ) 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)

Constitutive relationships for elastic deformation of clay rock: Data Analysis

Energy Technology Data Exchange (ETDEWEB)

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

2011-04-15

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

Acidic volcanic rock and its potential as an objective for uranium prospecting

International Nuclear Information System (INIS)

Rodriguez Torres, R.; Yza Dominguez, R.; Chavez Aguirre, R.; Constantino, H.E.S.E.

1976-01-01

The geographical distribution of recent Mexican volcanic rocks is continuous; the older formations are dispersed in isolated outcrops. Continental volcanic events, acidic and basal, took place in the Caenozoic, Mesozoic and Palaeozoic; basic submarine volcanism predominated in the Mesozoic, Palaeozoic and late Precambrian. Access to the Sierra Madre Occidental, a circum-Pacific mountain range covered by rhyolitic rocks, is limited, which restricts the sections studied. Calderas, sources of volcanic emission and preliminary litho-stratigraphic sections have been delimited on the eastern edge of the range. Subduction by the ocean magmatized the continent from the Permian onwards, extravasating and depositing cyclically various magmata through inverted and normal cortical throws. The Sierra Pena Blanca (Chihuahua) section consists of epiclastic and pyroclastic rocks. A calcareous conglomerate is overburdened by alternate basal tuffs and imbricates, forming five units. In the uraniferous district of the Sierra Pena Blanca the hydrothermal alteration argillitized both components of the ''Nopal'' formation. Primary minerals (pitchblende) are found together with silicification. Leaching favours secondary mineralization (uranium silicates) associated with opals. After extrapolation of the features, the following are considered worth-while objectives: the faces, offsets and prolongations of the Sierra Madre Occidental and the southern volcanic mesetas south of the Mexican Transcontinental Rift. Similar objectives of Mesozoic or Palaeozoic age exist in central and southern Mexico. Possible objectives for uranium are: the acidic volcanic rock of the southern and south-western United States of America, the circum-Pacific acidic volcanic rocks of North America and the acidic volcanic mesetas of Central America and in the Andes. (author)

Geology of the Nevada Test Site and nearby areas, southern Nevada

International Nuclear Information System (INIS)

Sinnock, S.

1982-10-01

The Department of Energy's Nevada Test Site (NTS) lies in the southern part of the Great Basin Section of the Basin and Range Physiographic Province. This report addresses the geological setting of the NTS in the context of the current waste isolation policy. The intent is to provide a synthesis of geological conditions at the NTS and nearby areas so that a general background of information is available for assessing the possible role of geology in providing protections for humans from buried radioactive wastes. The NTS is characterized by alluvium-filled, topgraphically closed valleys surrounded by ranges composed of Paleozoic sedimentary rocks and Tertiary volcanic tuffs and lavas. The Paleozoic rocks are a miogeosynclinal sequence of about 13,000 ft of pre-Cambrian to Cambrian clastic deposits (predominantly quartzites) overlain by about 14,000 ft of Cambrian through Devonian carbonates, 8000 ft of Mississippian argillites and quartzites, and 3000 ft of Pennsylvanian to Permian limestones. Tertiary volcanic rocks are predominatly silicic composition and were extruded from numerous eruptive centers during Miocene and Pliocene epochs. Within eruptive caldera depressions, volcanic deposits accumulated to perhaps 10,000 ft in total thickness, thinning to extinction outward from the calderas. Extrusion of minor amounts of basalts accompanied Pliocene and Pleistocene filling of structural basins with detritus from the ranges. Regional compressional and extensional structures as well as local volcanic structures occur in the NTS region. Normal extensional faulting coincided with the outbreak of volcanism during the Miocene and was superimposed on existing Mesozoic structures. Continued extensional deformation may be occurring at the present time

Constitutive relationships for elastic deformation of clay rock: Data Analysis

International Nuclear Information System (INIS)

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

2011-01-01

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

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)

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.

Some contrasting biostratigraphic links between the Baker and Olds Ferry Terranes, eastern Oregon

Science.gov (United States)

Nestell, Merlynd K.; Blome, Charles D.

2016-01-01

New stratigraphic and paleontologic data indicate that ophiolitic melange windows in the Olds Ferry terrane of eastern Oregon contain limestone blocks and chert that are somewhat different in age than those present in the adjacent Baker terrane melange. The melange windows in the Olds Ferry terrane occur as inliers in the flyschoid Early and Middle Jurassic age Weatherby Formation, which depositionally overlies the contact between the melange-rich Devonian to Upper Triassic rocks of the Baker terrane on the north, and Upper Triassic and Early Jurassic volcanic arc rocks of the Huntington Formation on the south. The Baker terrane and Huntington Formation represent fragments of a subduction complex and related volcanic island arc, whereas the Weatherby Formation consists of forearc basin sedimentary deposits. The tectonic blocks in the melange windows of the Weatherby Formation (in the Olds Ferry terrane) are dated by scarce biostratigraphic evidence as Upper Pennsylvanian to Lower Permian and Upper Triassic. In contrast, tectonic blocks of limestone in theBaker terrane yield mostly fusulinids and small foraminifers of Middle Pennsylvanian Moscovian age at one locality.Middle Permian (Guadalupian) Tethyan fusulinids and smaller foraminifers (neoschwagerinids and other Middle Permian genera) are present at a few other localities. Late Triassic conodonts and bryozoans are also present in a few of the Baker terrane tectonic blocks. These limestone blocks are generally embedded in Permian and Triassic radiolarian bearing chert or argillite. Based on conodont, radiolarian and fusulinid data, the age limits of the meange blocks in the Weatherby Formation range from Pennsylvanian to Late Triassic.

Experimental Simulation of Meteorite Ablation during Earth Entry Using a Plasma Wind Tunnel

Energy Technology Data Exchange (ETDEWEB)

Loehle, Stefan; Zander, Fabian; Hermann, Tobias; Eberhart, Martin; Meindl, Arne; Oefele, Rainer [High Enthalpy Flow Diagnostics Group, Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany); Vaubaillon, Jeremie; Colas, Francois [Institut de Mécanique Céleste et de Calcul des Éphémerides, Observatoire de Paris, Av. de l’Observatoire, Paris (France); Vernazza, Pierre; Drouard, Alexis [Laboratoire d’Astrophysique de Marseille, Aix Marseille Univ, CNRS, LAM, Marseille (France); Gattacceca, Jerome [CNRS, Aix-Marseille Univ, IRD, Coll France, CEREGE, Aix-en-Provence,France, Avenue Louis Philibert, 13545 Aix-en-Provence (France)

2017-03-10

Three different types of rocks were tested in a high enthalpy air plasma flow. Two terrestrial rocks, basalt and argillite, and an ordinary chondrite, with a 10 mm diameter cylindrical shape were tested in order to observe decomposition, potential fragmentation, and spectral signature. The goal was to simulate meteoroid ablation to interpret meteor observation and compare these observations with ground based measurements. The test flow with a local mass-specific enthalpy of 70 MJ kg{sup −1} results in a surface heat flux at the meteorite fragment surface of approximately 16 MW m{sup −2}. The stagnation pressure is 24 hPa, which corresponds to a flight condition in the upper atmosphere around 80 km assuming an entry velocity of 10 km s{sup −1}. Five different diagnostic methods were applied simultaneously to characterize the meteorite fragmentation and destruction in the ground test: short exposure photography, regular video, high-speed imaging with 10 kHz frame rate, thermography, and Echelle emission spectroscopy. This is the first time that comprehensive testing of various meteorite fragments under the same flow condition was conducted. The data sets indeed show typical meteorite ablation behavior. The cylindrically shaped fragments melt and evaporate within about 4 s. The spectral data allow the identification of the material from the spectra which is of particular importance for future spectroscopic meteor observations. For the tested ordinary chondrite sample a comparison to an observed meteor spectra shows good agreement. The present data show that this testing methodology reproduces the ablation phenomena of meteoritic material alongside the corresponding spectral signatures.

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)

Geology mineralogy, structure and texture of Agh-Otagh base- precious metal mineralization (North Takab

Directory of Open Access Journals (Sweden)

Nahid Rahmati

2017-07-01

Full Text Available The Agh-Otagh mineralization area in the north of Takab, was formed within the andesistic tuffaceous rocks of the Oligo- Miocene age. Mineralization include polymetallic (Cu-Pb-Zn-Au-Ag quartz veins and silicified zones, which occurred as breccia and vein- veinlets with comb, cockade and disseminated textures. Chalcopyrite, pyrite, galena and sphalerite are common ore minerals. Alteration zones consist of silicification, sericitization, argillitic, propelitic and carbonatization. Cu-Au mineralization is associated with silicification and sericitization. Analytical results of the samples from the ore- bearing quartz veins and the silicified zones indicate that the highest grade for Au is 664 ppb (ave.181 ppb. The highest and the average grades for Ag, Cu, Pb, and Zn are 120 ppm (300 ppm, 1.3 % (0.38 %, 5.5 % (0.06 % and 4.5 % (0.28 %, respectively. The investigations indicate that the Agh-Otagh mineralization was formed in four stages. In the first stage or the pre-mineralization stage, the host rock, as a result of hydrothermal process, underwent brecciation and some quartz veins and siliceous cap were formed. In the second stage or the mineralization stage the sulfide minerals formed within the quartz veins and silicification zones developed at the third stage, some unmineralized quartz, barite and carbonate vein- veinlets crosscut the previous stages. The last stage of mineralization related to supergene processes. Based on geological, mineralogical, alteration, structural and textural evidences, the Agh-Otagh base- precious metal mineralization is similar to the medium sulfidation epithermal deposits.

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)

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)

Characterization and modeling of natural tracers' transfers through the argillites of Tournemire (France); Caracterisation et modelisation des transferts de traceurs naturels dans les argilites de Tournemire

Energy Technology Data Exchange (ETDEWEB)

Patriarche, D

2001-09-13

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 {sup 18}O 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)

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)

Mathieu, Regis

1999-01-01

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 18 O 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% CaCl 2 ), 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 C 9 and C 10 -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 (δ 13 C=-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 O 2 , CH 4 and CO 2 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 (δ 13 C= 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 87 Sr/ 86 Sr 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 87 Sr/ 86 Sr 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) [fr

Paleozoic stratigraphy and tectonics in northernmost Nevada: Implications for the nature of the Antler orogeny

Energy Technology Data Exchange (ETDEWEB)

Ketner, K.B. (Geological Survey, Denver, CO (United States)); Ehman, K.D. (Exxon Production Research Co., Houston, TX (United States)); Repetski, J.E.; Stamm, R.G.; Wardlaw, B.R. (Geological Survey, Reston, VA (United States))

1993-04-01

Recent mapping and revised ages have clarified geologic relations in northern Nevada. In the Bull Run Mountains-Copper Mountains area, Proterozoic quartzite, phyllite, marble, and greenstone are overlain successively, depositionally, and nearly concordantly by the Cambrian Prospect Mountain Quartzite, Pioche Shale, and Eldorado Dolomite; the Cambrian to Ordovician Tennessee Mountain Formation composed of limestone, siltstone, and greenstone; the Ordovician Valmy Formation composed of a lower member of greenstone, limestone, mudstone, and chert, and an upper member of quartzite and argillite; and, disconformably by a Mississippian sequence of interbedded conglomerate, limestone, siltstone, and greenstone. The Prospect Mountain, Pioche, and Eldorado form a relatively shallow-water, shelf sequence containing trilobites and displaying cross-bedding, ooliths, oncolites, and fenestral fabric. The overlying Tennessee Mountain and Valmy are devoid of such features and contain many black, finely laminated, and graded strata, suggesting a deeper-water environment. This upper Proterozoic to Permian sequence is interpreted as indicating: (1) increased tectonic subsidence or sea-level rise in the latter part of the Cambrian; (2) elevation above sea level and erosion of Devonian, Silurian, and Upper Ordovician rocks in earliest Mississippian; (3) subsidence below sea level in later Early Mississippian; (4) elevation above sea level with sporadic, moderate deformation, and local, deep erosion in medial Pennsylvanian; (5) subsidence below sea level in medial Pennsylvanian or later; (6) intermittent eruption of basic volcanics peaking in Early Ordovician and again in Mississippian. The disconformable relation between the Valmy Formation and overlying Mississippian strata indicates that the Antler orogeny of earliest Mississippian age, here consisted primarily of uplift and deep erosion. Evidence of strong Early Mississippian folding and contractional faulting is not apparent.

Scientific investigation in deep wells for nuclear waste disposal studies at the Meuse/Haute Marne underground research laboratory, Northeastern France

Science.gov (United States)

Delay, Jacques; Rebours, Hervé; Vinsot, Agnès; Robin, Pierre

Andra, the French National Radioactive Waste Management Agency, is constructing an underground test facility to study the feasibility of a radioactive waste disposal in the Jurassic-age Callovo-Oxfordian argillites. This paper describes the processes, the methods and results of a scientific characterization program carried out from the surface via deep boreholes with the aim to build a research facility for radioactive waste disposal. In particular this paper shows the evolution of the drilling programs and the borehole set up due to the refinement of the scientific objectives from 1994 to 2004. The pre-investigation phase on the Meuse/Haute-Marne site started in 1994. It consisted in drilling seven scientific boreholes. This phase, completed in 1996, led to the first regional geological cross-section showing the main geometrical characteristics of the host rock. Investigations on the laboratory site prior to the sinking of two shafts started in November 1999. The sinking of the shafts started in September 2000 with the auxiliary shaft completed in October 2004. The experimental gallery, at a depth of 445 m in the main shaft, was in operation by end 2004. During the construction of the laboratory, two major scientific programs were initiated to improve the existing knowledge of the regional hydrogeological characteristics and to accelerate the process of data acquisition on the shales. The aim of the 2003 hydrogeological drilling program was to determine, at regional scale, the properties of groundwater transport and to sample the water in the Oxfordian and Dogger limestones. The 2003-2004 programs consisted in drilling nine deep boreholes, four of which were slanted, to achieve an accurate definition of the structural features.

Generic Crystalline Disposal Reference Case

Energy Technology Data Exchange (ETDEWEB)

Painter, Scott Leroy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harp, Dylan Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Perry, Frank Vinton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wang, Yifeng [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-02-20

A generic reference case for disposal of spent nuclear fuel and high-level radioactive waste in crystalline rock is outlined. The generic cases are intended to support development of disposal system modeling capability by establishing relevant baseline conditions and parameters. Establishment of a generic reference case requires that the emplacement concept, waste inventory, waste form, waste package, backfill/buffer properties, EBS failure scenarios, host rock properties, and biosphere be specified. The focus in this report is on those elements that are unique to crystalline disposal, especially the geosphere representation. Three emplacement concepts are suggested for further analyses: a waste packages containing 4 PWR assemblies emplaced in boreholes in the floors of tunnels (KBS-3 concept), a 12-assembly waste package emplaced in tunnels, and a 32-assembly dual purpose canister emplaced in tunnels. In addition, three failure scenarios were suggested for future use: a nominal scenario involving corrosion of the waste package in the tunnel emplacement concepts, a manufacturing defect scenario applicable to the KBS-3 concept, and a disruptive glaciation scenario applicable to both emplacement concepts. The computational approaches required to analyze EBS failure and transport processes in a crystalline rock repository are similar to those of argillite/shale, with the most significant difference being that the EBS in a crystalline rock repository will likely experience highly heterogeneous flow rates, which should be represented in the model. The computational approaches required to analyze radionuclide transport in the natural system are very different because of the highly channelized nature of fracture flow. Computational workflows tailored to crystalline rock based on discrete transport pathways extracted from discrete fracture network models are recommended.

Experimental Study on the Interaction Between Contacting Barrier Materials for Containment of Radioactive Wastes

Science.gov (United States)

Huang, W. H.; Chang, H. C.

2017-12-01

The disposal of low- and intermediate-level radioactive wastes requires use of multi-barriers for isolation of the wastes from the biosphere. Typically, the engineered barriers are composed of a concrete vault, buffer and backfill materials. Zhishin clay and Black Hill bentonite were used as raw clay material in making buffer and backfill materials in this study. These clays were compacted to make buffer material, or mixed with Taitung area argillite to produce backfill material for potential application as barriers for the disposal of low- and intermediate-level radioactive wastes. The interaction between concrete barrier and the buffer/backfill material is simulated by an accelerated migration test to investigate the effect of contacting concrete on the expected functions of buffer/backfill material. The results show buffer material close to the contact with concrete exhibits significant change in the ratio of calcium/sodium exchange capacity, due to the move of calcium ions released from the concrete. The shorter the distance from the contacting interface, the ratio of the calcium/sodium concentration in buffer/backfill materials increases. The longer the distance from the interface, the effect of the contact on alteration in clays become less significant. Also, some decreases in swelling capacity in the buffer/backfill material near the concrete-backfill interface are noted. Finally, a comparison is made between Zhisin clay and Balck Hill bentonite on the interaction between concrete and the two clays. Black Hill bentonite was found to be influenced more by the interaction, because of the higher content of montmorillonite. On the other hand, being a mixture of clay and sand, backfill material is less affected by the decalsification of concrete at the contact than buffer material.

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

International Nuclear Information System (INIS)

Maghsoudloo Mahalli, M.; Shafiei Bafti, B.

2016-01-01

Mineralogical characteristics combined with geochemical data show that anomalous values of Fe in studied carbonate argillite formations with respect to common sedimentary rocks are related to the abundance of iron-bearing oolites as oxides such as hematite and goethite, and the clay mineral chamosite. Based on Fe, Mg and Ca concentrations, oolitic iron formations can be divided into low-grade and high-grade iron formations. The former is characterized by chamosite and calcite, whereas the latter consists ofhematite and calcite. This research, along with available paleo-geographic and sedimentological information suggests that the iron for the formation of iron oolites was available from normal sea water and Fe could be carried as clastic particles along with clays or coating of clay particles derived from weathering and erosion of shales from adjacent land. High contents of K and Si in oolitic iron horizons, the presence of detrital zircon, quartz and clay minerals within oolites and also in the matrix of these rocks confirm the proposed model and show the important role of Fe-bearing clay minerals in the genesis of the primary chamositic oolites in an environment with p H=5-9 and medium-weak redox conditions (Maynard, 1983; Maynard, 1986). The abundance of hematite relative to goethite in the Fe-oolites, dense and elliptical oolites as well as the frequent occurrence of calcite veinlets cutting oolite beds has been attributed to diagenetic processes and the modification of chamosite and goethite to hematite. Our findings indicate that the studied members can be classified as low-grade oolitic iron formation (average 21 wt.% Fe) which do not have economic importance at present.

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

International Nuclear Information System (INIS)

Yanev, P.I.; Owen, G.N.

1978-04-01

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

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)

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

Sensitivity analysis of alkaline plume modelling: influence of mineralogy

International Nuclear Information System (INIS)

Gaboreau, S.; Claret, F.; Marty, N.; Burnol, A.; Tournassat, C.; Gaucher, E.C.; Munier, I.; Michau, N.; Cochepin, B.

2010-01-01

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

Kinematic analysis of melange fabrics: Examples and applications from the McHugh Complex, Kenai Peninsula, Alaska

Science.gov (United States)

Kusky, T.M.; Bradley, D.C.

1999-01-01

Permian to Cretaceous melange of the McHugh Complex on the Kenai Peninsula, south-central Alaska includes blocks and belts of graywacke, argillite, limestone, chert, basalt, gabbro, and ultramafic rocks, intruded by a variety of igneous rocks. An oceanic plate stratigraphy is repeated hundreds of times across the map area, but most structures at the outcrop scale extend lithological layering. Strong rheological units occur as blocks within a matrix that flowed around the competent blocks during deformation, forming broken formation and melange. Deformation was noncoaxial, and disruption of primary layering was a consequence of general strain driven by plate convergence in a relatively narrow zone between the overriding accretionary wedge and the downgoing, generally thinly sedimented oceanic plate. Soft-sediment deformation processes do not appear to have played a major role in the formation of the melange. A model for deformation at the toe of the wedge is proposed in which layers oriented at low angles to ??1 are contracted in both the brittle and ductile regimes, layers at 30-45??to ??1 are extended in the brittle regime and contracted in the ductile regime, and layers at angles greater than 45??to ??1 are extended in both the brittle and ductile regimes. Imbrication in thrust duplexes occurs at deeper levels within the wedge. Many structures within melange of the McHugh Complex are asymmetric and record kinematic information consistent with the inferred structural setting in an accretionary wedge. A displacement field for the McHugh Complex on the lower Kenai Peninsula includes three belts: an inboard belt of Late Triassic rocks records west-to-east-directed slip of hanging walls, a central belt of predominantly Early Jurassic rocks records north-south directed displacements, and Early Cretaceous rocks in an outboard belt preserve southwest-northeast directed slip vectors. Although precise ages of accretion are unknown, slip directions are compatible with

Numerical modelling of the long term mechanical behaviour of a storage cell for high level nuclear wastes

International Nuclear Information System (INIS)

Bian, H.B.; Jia, Y.; Duveau, G.; Shao, J.F.; Poutrel, A.

2010-01-01

Document available in extended abstract form only. In France, a clay formation, called Callovo-Oxfordian clay, is considered as potential geological barrier for storage of radioactive wastes. An underground research laboratory is constructed in this clay layer in Bure (CMHM). The French Radioactive Waste Management Agency (Andra) plans to conduct a series of full scale experiments in the Bure Underground Research Laboratory in order to study the coupled Chemo- Thermo-Hydraulic-Mechanical processes due to the excavation, ventilation, subsequent backfilling/sealing, corrosion of metal components and heat release from the radioactive wasters. These phenomena will occur in the storage structures and the geologic barrier for a short/very long period of time. Especially for the High-Level Wastes, due to the important increase of temperature released by the waste packages, the behaviour of geological barrier is perhaps perturbed and the design of repository is also influenced in terms of admissible thermal loading. In this paper, a disposal cell for the radioactive High-Level Wastes (HLW) is studied in order to analyser the coupled phenomena evolving in the HLW storage. The carbon steel is adopted as the first choice material for the container of waste because of its relevant geochemical condition. In the underground radioactive wastes storage, due to the arrival of water from the geological formation, the metallic components will be corroded, by step, with a decrease of mechanical resistance and a generated supplementary volume. The space between the metallic container and the host rock will then be closed under the combination of metallic corrosion and the behaviour differs of Callovo-Oxfordian clay. As results, important stress will be created on the interface of Callovo-Oxfordian clay and wastes packages. In addition, local hydration of barrier modifies the water infiltration from the Callovo-Oxfordian clay and the stress distribution in the argillite. According to

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

International Nuclear Information System (INIS)

2005-01-01

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.)

Linking carbon and hydrologic fluxes in the critical zone: Observations from high-frequency monitoring of a weathered bedrock vadose zone

Science.gov (United States)

Tune, A. K.; Druhan, J. L.; Wang, J.; Cargill, S.; Murphy, C.; Rempe, D. M.

2017-12-01

A principle challenge in quantifying feedbacks between continental weathering and atmospheric CO2 is to improve understanding of how biogeochemical processes in the critical zone influence the distribution and mobility of organic and inorganic carbon. In particular, in landscapes characterized by thin soils and heterogeneous weathered and fractured bedrock, little data exist to inform and constrain predictive models for carbon dynamics. Here, we present the results of an intensive water and gas sampling campaign across an 18 m thick, variably saturated argillite weathering profile in the Eel River CZO. We monitor water content in situ and regularly collect samples of freely-draining water, tightly-held water, and gas through wet and dry seasons using a novel Vadose-zone Monitoring System (VMS) consisting of sensors and samplers distributed across a 20 m long inclined borehole. This novel approach facilitates the interception of gas and water during transport across the entire variably saturated weathering profile. The data demonstrate that seasonal changes in saturation control the vertical distribution and mobility of carbon in the fractured critical zone. Concentrations of gaseous CO2, O2, and dissolved organic and inorganic carbon fluctuate significantly and repeatably with seasonal additions of water infiltrating the weathered bedrock. A persistent vertical structure in the concentrations of dissolved phases and gas concentrations broadly corresponds to depths associated with unsaturated, seasonally saturated, and chronically saturated zones. Associated variations in the vertical structure of mineralogy and elemental composition, including solid phase organic carbon content, are observed in core obtained during drilling. Together, our observations indicate significant respiration of organic carbon at depths greater than the base of the soil, and thus motivate further investigation of the role of heterogeneous weathered, bedrock environments, which are needed to

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

International Nuclear Information System (INIS)

Milham, L.; Craw, D.

2009-01-01

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 cm 3 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.

Abiotic nitrate reduction in the presence of steel material and hydrogen in cementitious environments

International Nuclear Information System (INIS)

Truche, L.; Berger, G.; Albrecht, A.

2012-01-01

Document available in extended abstract form only. Abiotic nitrate reduction induced by different electron donors represents a major reaction of interest in the context of disposal of nuclear waste containing such oxyanions (Honda et al., 2006; Katsounaros et al., 2009). These wastes are characterized, amongst others by the coexistence of oxyanions (nitrate, phosphate, sulfate...) and potentially reducing agents such as organic matter, native metals and hydrogen gas formed or from package material via radiolysis or anaerobic corrosion. In addition to the large number of reactants present in the waste itself, the medium-level long-lived (MAVL) waste concept is based on large masses of concrete and steel in part used for primary waste containers as well as armored cement over pack and engineered barrier; a concept that guarantees the mechanical stability of both the waste container and the waste cell. In this experimental study we evaluate the consequences of steel material (carbon steel and 316L stainless steel) from waste canisters and construction material (concrete and Callovo- Oxfordian argillite), as well as magnetite as their possible corrosion by-products, on the reduction of aqueous nitrate in the presence of hydrogen. A parametric study (0 2 ) - ] 2+ , Fe 2+ ) that can act as electron donors. This experimental study demonstrates that abiotic nitrate reduction induced by the combination of steel materials and hydrogen is a likely process under waste cell conditions, thus applicable to cases where nitrate-bearing waste (i.e. nuclear) is disposed in near-surface or in deep geological settings. Depending on the nature of the steel, the reaction may exhibit different kinetic features that would require dedicated assessment. An increase in nitrate concentrat ions above the steel saturation level of 10 mM (Fig. 1; beyond the range of the current study) may also have an influence on reaction processes and kinetics and thus influence nitrate reactivity. (authors)

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

Energy Technology Data Exchange (ETDEWEB)

Harmon, K.M.; Lakey, L.T.; Leigh, I.W.

1984-07-01

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.

Assessment of potential radionuclide transport in site-specific geologic formations

International Nuclear Information System (INIS)

Dosch, R.G.

1980-08-01

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

Bedrock geologic map of the northern Alaska Peninsula area, southwestern Alaska

Science.gov (United States)

Wilson, Frederic H.; Blodgett, Robert B.; Blome, Charles D.; Mohadjer, Solmaz; Preller, Cindi C.; Klimasauskas, Edward P.; Gamble, Bruce M.; Coonrad, Warren L.

2017-03-03

The northern Alaska Peninsula is a region of transition from the classic magmatic arc geology of the Alaska Peninsula to a Proterozoic and early Paleozoic carbonate platform and then to the poorly understood, tectonically complex sedimentary basins of southwestern Alaska. Physiographically, the region ranges from the high glaciated mountains of the Alaska-Aleutian Range to the coastal lowlands of Cook Inlet on the east and Bristol Bay on the southwest. The lower Ahklun Mountains and finger lakes on the west side of the map area show strong effects from glaciation. Structurally, a number of major faults cut the map area. Most important of these are the Bruin Bay Fault that parallels the coast of Cook Inlet, the Lake Clark Fault that cuts diagonally northeast to southwest across the eastern part of the map area, and the presently active Holitna Fault to the northwest that cuts surficial deposits.Distinctive rock packages assigned to three provinces are overlain by younger sedimentary rocks and intruded by widely dispersed latest Cretaceous and (or) early Tertiary granitic rocks. Much of the east half of the map area lies in the Alaska-Aleutian Range province; the Jurassic to Tertiary Alaska-Aleutian Range batholith and derivative Jurassic sedimentary rocks form the core of this province, which is intruded and overlain by the Aleutian magmatic arc. The Lime Hills province, the carbonate platform, occurs in the north-central part of the map area. The Paleozoic and Mesozoic Ahklun Mountains province in the western part of the map area includes abundant chert, argillite, and graywacke and lesser limestone, basalt, and tectonic mélange. The Kuskokwim Group, an Upper Cretaceous turbidite sequence, is extensively exposed and bounds all three provinces in the west-central part of the map area.

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

International Nuclear Information System (INIS)

Harmon, K.M.; Lakey, L.T.; Leigh, I.W.

1984-07-01

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

Contact angles at the water-air interface of hydrocarbon-contaminated soils and clay minerals

Science.gov (United States)

Sofinskaya, O. A.; Kosterin, A. V.; Kosterina, E. A.

2016-12-01

Contact angles at the water-air interface have been measured for triturated preparations of clays and soils in order to assess changes in their hydrophobic properties under the effect of oil hydrocarbons. Tasks have been to determine the dynamics of contact angle under soil wetting conditions and to reveal the effect of chemical removal of organic matter from soils on the hydrophilicity of preparations. The potentialities of static and dynamic drop tests for assessing the hydrophilic-hydrophobic properties of soils have been estimated. Clays (kaolinite, gumbrine, and argillite) have been investigated, as well as plow horizons of soils from the Republic of Tatarstan: heavy loamy leached chernozem, medium loamy dark gray forest soil, and light loamy soddy-calcareous soil. The soils have been contaminated with raw oil and kerosene at rates of 0.1-3 wt %. In the uncontaminated and contaminated chernozem, capillary water capacity has been maintained for 250 days. The contact angles have been found to depend on the degree of dispersion of powdered preparation, the main type of clay minerals in the soil, the presence and amount of oxidation-resistant soil organic matter, and the soil-water contact time. Characteristic parameters of mathematical models for drop behavior on triturated preparations have been calculated. Contamination with hydrocarbons has resulted in a reliable increase in the contact angles of soil preparations. The hydrophobization of soil surface in chernozem is more active than in soils poorer in organic matter. The complete restoration of the hydrophilic properties of soils after hydrocarbon contamination is due to the oxidation of easily oxidizable organic matter at the low content of humus, or to wetting during several months in the absence of the mazut fraction.

Characterization and quantification by mass spectrometry of mobile organic matter from clay rock: influence of the origin and of the sampling

International Nuclear Information System (INIS)

Huclier-Markai, S.; Landesman, C.; Montavon, G.; Grambow, B.; Monteau, F.; Fernandez, A.M.; Vinsot, A.

2012-01-01

Document available in extended abstract form only. In environmental studies, Natural Organic Matter (NOM) plays a key role on the bioavailability and the toxicity of metallic compounds. If one wants to evaluate the mobility of heavy metals / radionuclides, which is in natura in most of the cases dependant on their interactions with NOM. One part of the organic inventory in the Callovo-Oxfordian formation (COx) exists as small dissolved compounds in the pore water but the weak content and the weak porosity of the formation (∼ 8 % of water in weight) make the complexation study with metal ions difficult. One part of the organic matter attached to the sediment (∼ 1 % in weight) can be mobilized in a synthetic pore water 1 and can be considered as similar to in situ pore water dissolved organic matter (DOM) regarding its size distribution. The collection of clay pore water has been done through percolation experiment, a unique and original experimental process developed to get pore water from a core sample,that have been described previously. From these experiments, it was shown that mobile organic matter concentration could reach 0.01 mol C/L by application of a pressure gradient up to 100 bars. Since part of the OM from the COx is known to be sensitive to air oxidation, the characterization and quantification of DOM were then performed under anoxic conditions (about - 170 mV vs Standard Hydrogen Electrode SHE). In addition, the chemical composition of NOM contained in the pore water from the argillite clay rock has been determined in in-situ like conditions by ESI-MS and APCI-MS, which are suitable techniques to identify the chemical composition of NOM contained in the COx pore water available from boreholes. Mostly low molecular weight molecules were identified, of whom structural features observed were mainly acidic compounds, fatty acids as well as aldehydes and amino acids. Fulvic and Humic Acids have such low concentrations in the COx formation, leading to a

Elastic and nonlinear behaviour of argillaceous rocks under combined moisture and mechanical loads investigated by means of multiscale full-field strain measurement techniques

International Nuclear Information System (INIS)

Yang, D.S.; Nguyen Minh, D.; Chanchole, S.; Gharbi, H.; Valli, P.; Bornert, M.

2010-01-01

Document available in extended abstract form only. The construction of underground nuclear waste repositories will strongly disturb the initial thermo-hydro-chemo-mechanical equilibrium of the site. In addition to direct mechanical perturbations during excavation, which induce redistribution of the stresses and possible damage of the surrounding rock mass, the ventilation of the galleries will also modify the moisture content of the rock, resulting in shrinking or swelling, and more generally modifying the physical-chemical properties of the material. Safety concerns about preservation of confining properties of rock mass at short and long time scales require a deep understanding of the hydro-mechanical behavior of the host rock. In particular the dependence of elastic, possibly anisotropic, moduli and nonlinear properties (plasticity, damage, creep...) as a function of the moisture level, need to be quantified. In addition, in order to construct physically based micromechanical models of these dependencies, the various micro-mechanisms at their origin and their characteristic scales need to be identified. Various independent studies agree on the decrease of overall rigidity and failure stress of argillite with increasing humidity. A recent study making use of optical full-field strain measurement techniques on centi-metric samples under uniaxial compression suggests that this apparent decrease of elastic properties on wet samples can be essentially explained by the presence of a millimetric network of 'meso-cracks', induced by the preliminary unconfined hydration process. Indeed, thanks to the full-field measurement technique, it was possible to show that the mechanical response of undamaged areas, in-between cracks, was very similar at all moisture contents, both in terms of average strains and strain fluctuations at the micrometric scale of the composite structure of the rock (matrix clay + other mineral inclusions). The preliminary hydro

Inventory of geochemical sensors available for monitoring an underground site of nuclear waste repository research pathways for new developments

International Nuclear Information System (INIS)

Ignatiadis, I.; Gaucher, E.; Buschaert, S.

2010-01-01

methodologies and tools for these parameters indicate that today there are not suitable geochemical sensors for monitoring nuclear waste storing systems. On the basis of this report, we are led to propose some realistic pathways of research and development to be initiated or continue to mitigate the lack of geochemical sensors dedicated to the underground storage of nuclear waste. For that purpose, R and D pathways will be (i) the development of geophysical-electrochemical sensors and (ii) the development and manufacture of geochemical sensors made of robust and unalterable material (gold, platinum, glassy carbon). They must possess active principles everlasting, or protected or restored easily. Moreover, solid-state sensors fabricated with a few component of the argillaceous formations (pyrite, raw or purified argillite K119) or silicon semiconductor technology (such as ion sensitive field effect transistors, ISFETs) for measuring pH and interdigitated structures (IDS) for measuring conductivity and redox potential can be designed for use. Response characteristics of these sensors must be tested in aqueous samples with compositions similar to those present inside an underground repository and results were compared with those obtained with commercial electrodes obtaining a good agreement between commercial and the sensors. Electrochemical methods will be in the base of the sensors assessments. These approaches will be consisted in the continuous or semi-continuous analysis of large surface electrodes (pyrite, argillite, ) immersed in solutions with or without oxidant (nitrate, selenate and selenite) or reducer (sulfide, Fe 2+ ). The electrochemical behavior of these electrodes was compared to those of known inert and unattackable electrodes (Pt, Au, glassy carbon) positioned in the same operating conditions. Measurements realized by voltammetry (at open circuit potential and cyclic voltammetry), by Tafel polarization analysis and by electrochemical impedance spectroscopy (EIS

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

Thick-skinned tectonics in a Late Cretaceous-Neogene intracontinental belt (High Atlas Mountains, Morocco): The flat-ramp fault control on basement shortening and cover folding

Science.gov (United States)

Fekkak, A.; Ouanaimi, H.; Michard, A.; Soulaimani, A.; Ettachfini, E. M.; Berrada, I.; El Arabi, H.; Lagnaoui, A.; Saddiqi, O.

2018-04-01

Most of the structural studies of the intracontinental High Atlas belt of Morocco have dealt with the central part of the belt, whose basement does not crop out. Here we study the Alpine deformation of the North Subatlas Zone, which is the part of the Western High Atlas (WHA) Paleozoic Massif that involves both Paleozoic basement units and remnants of their Mesozoic-Cenozoic cover formations. Our aim is to better constrain the geometry and kinematics of the basement faults during the Alpine shortening. Based on detail mapping, satellite imagery and field observations, we describe an array of sub-equatorial, transverse and oblique faults between the WHA Axial Zone and the Haouz Neogene basin. They define a mosaic of basement blocks pushed upon one another and upon the Haouz basement along the North Atlas Fault (NAF). The Axial Zone makes up the hanging-wall of the Adassil-Medinet Fault (AMF) south of this mosaic. The faults generally presents flat-ramp-flat geometry linked to the activation of multiple décollement levels, either within the basement where its foliation is subhorizontal or within favourable cover formations (Jurassic evaporites, Lower Cretaceous silty red beds, Upper Cretaceous evaporitic marls, Neogene basal argillites). The occurrence of the North Atlas detachment (NAD) allowed folded pop-up units to develop in front of the propagating NAF. Shortening began as early as the Campanian-Maastrichtian along the AMF. The direction of the maximum horizontal stress rotated from NNE-SSW to NNW-SSE from the Maastrichtian-Paleocene to the Neogene. The amount of shortening reaches 20% in the Azegour transect. This compares with the shortening amount published for the central-eastern High Atlas, suggesting that similar structures characterize the Paleozoic basement all along the belt. The WHA thick-skinned tectonics evokes that of the frontal Sevier belt and of the external Western Alps, although with a much minor pre-inversion burial.

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 induced

Modeling of excavation induced coupled hydraulic-mechanical processes in claystone

International Nuclear Information System (INIS)

Massmann, Jobst

2009-01-01

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 induced

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

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

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

International Nuclear Information System (INIS)

Becker, J.A.; Craw, D.; Horton, T.; Chamberlain, C.P.

2000-01-01

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 δ 18 O ranging from 11.1 to 25.6 per thousand, and δ 13 C 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

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

International Nuclear Information System (INIS)

De Windt, Laurent; Marsal, François; Corvisier, Jérôme; Pellegrini, Delphine

2014-01-01

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 H 2 production) and oxidizing conditions at the front of the cell (with oxic corrosion of steel). The extent of the oxidizing/reducing front in the

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)

2005-06-01

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

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

International Nuclear Information System (INIS)

Carrier, Benoit; Vandamme, Matthieu; Ebrahimi, Davoud; Whittle, Andrew J.; Pellenq, Roland J.M.; Van Damme, Henri

2012-01-01

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 Ca 2+ -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

Reconstructing the Waipaoa Sedimentary System at the LGM

Science.gov (United States)

Upton, P.; Kettner, A. J.; Litchfield, N. J.; Orpin, A. R.

2009-12-01

The Waipaoa River catchment on New Zealand’s north-eastern coast has a mean annual suspended yield of 6780 t km-2 yr-1. The compact, mountainous and short reach of the Waipaoa River watershed produces among the highest sediment yields per unit area globally. Here, deforested and steep hillslopes composed of extremely weak mudstone argillite lithologies are exposed to a vigorous maritime climate. Sediment from the Waipaoa River is trapped in active tectonic basins on the shelf and slope. Waipaoa River water and sediment discharge have been modeled for the past 3000 years using HydroTrend, a climate-driven hydrological model and the results compared with floodplain and shelf sediment records (Kettner et al., 2007; 2009). In this study, we extend the existing HydroTrend model back to the Last Glacial Maximum (LGM, just prior to 18 ka), to investigate changes in suspended sediment load and bedload since that time. During the LGM the Waipaoa River catchment was approximately twice its current size, with the river mouth and coastline located near the current shelf break as a consequence of lower sea level. LGM pebble-cobble gravels in terraces and in relict shelf deposits indicate the river transported coarser bedload than during the Holocene. Climate models suggest that the region was colder and drier than present (Drost et al., 2007), consistent with the presence of loess and recycled pollen (Berryman et al. 2000; McGlone, 2001). The LGM vegetation was dominated by scrub and grassland (McGlone et al. 1984; McGlone, 2001), similar to the deforested vegetation cover in the watershed today. Preliminary HydroTrend simulations predict that, given the increased catchment, similar vegetation cover and landscape susceptibility to erosion, the suspended sediment flux of the LGM Waipaoa catchment was 10-15% higher than during the late Holocene. However, when considered relative to unit area, the LGM suspended sediment yield was perhaps 60% lower than during the late Holocene

Clay matrix voltammetry

International Nuclear Information System (INIS)

Perdicakis, Michel

2012-01-01

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

Porosity model for simultaneous radionuclide transfer in compact clay

International Nuclear Information System (INIS)

Grambow, B.; Ribet, S.; Landesman, C.; Altman, S.

2010-01-01

is acceptable, while a slight underestimation for Cs is observed at low bentonite densities. The model can be applied directly to assess the mass transfer in argillite as function of smectite and total water content. Comparison to HTO and anion transport under diffusive/advective conditions gave reasonable representation of breakthrough curves in high pressure flow through experiments in percolation cells. (authors)

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

International Nuclear Information System (INIS)

Rolland, A.

2013-01-01

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

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

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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

A paleoenvironmental study of subsurface Quaternary sediments at Wainuiomata, Wellington, New Zealand, and tectonic implications

Energy Technology Data Exchange (ETDEWEB)

Begg, J G; Mildenhall, D C; Lyon, G L; Stephenson, W R; Funnell, R H; Van Dissen, R J; Bannister, S; Brown, L J [Institute of Geological and Nuclear Sciences Ltd., Lower Hutt (New Zealand); Pillans, B; Harper, M A [Research School of Earth Sciences, Victoria University of Wellington, Wellington (New Zealand); Whitton, J [Manaaki Whenua - Landcare Research, Lower Hutt, (New Zealand)

1994-12-31

A stratigraphic drillhole (WS-1) sited on the floor of Wainuiomata Valley near Lower Hutt, revealed a 61.6 m thick Quaternary sequence overlying Torlesse Supergroup greywacke sandstone and argillite. The Quaternary sediments consist of three sequences separated by disconformities. The lower sequence, 10.7 m thick (61.6-50.9 m), consists of fluvial sediments of probable early Quaternary age. The middle sequence, about 48.3 m in thickness (50.9-c. 2.6 m), spans most of the Last Glaciation. Fluvial/overbnak (50.9-42.0 m), floodplain/swamp (42.9-34.5 m), and fluvial (34.5-31.3 m) sediments overlie the disconformity at 50.9 m. Conformably overlying these sediments are swamp and lacustrine deposits between 31.3 and 4.1 m. Diatoms and algal spores and coenobia show the existence of an extensive lake during much of this sequence, from 25.6 to 4.0 m. at the peak of its development, at a drillhole depth of c. 23 m, the lake was >10 m deep and had a high algal biomass. Kawakawa Tephra (22 600 yr b.p.) occurs near the top of the middle sequence at 4.1 m depth. The upper sequence, of Holocene-Recent age, is <2.6 m thick, including .06 m of fill. The existence of sediments of the lower sequence of at least Castlecliffian age (early Pleistocene) uncomformably overlying basement greywacke provides a minimum age for the K-surface in the area. The Last Glacial sediments show evidence of ponfing, which may be a result of one factor or a more of the following: ponding behind an aggradational terrace of the Wainuiomata River; landslide blockage of the Black Stream drainage near its confluence with Wainuiomata River; and tectonic deformation. Progressive tectonic deformation since the start of the Last Glaciation is considered the most likely dominant factor. This has resulted in the elevation of greywacke basement near the junction of Black Stream and Wainuiomata River. The nature of the deformation - faulting, tilting, and/or folding - has not been established. 38 refs,6 figs,2 tables.

Preliminary Result of Geophysical Some Studieson the Nariinsukhait Coal Deposit

Science.gov (United States)

Norov, B.; Purevjav, N.; Roy, D. K., Sr.

2017-12-01

Nariinsukhait coal deposit has a strategic importance on Mongolian national economic development. The deposit is located in Gurvan-tes of the Umnu-gobi province, as 849 km south-west away from Ulaanbaatar. The deposit in geographically, belongs to Gobi Altai region region of the Altai mountain region. The area contains Permian, Cretaceous, Jurassic, Triassic age of sediments. Sediments are red or sedimentary cover on some part of area (Minjin. Ch., Batnyam. D., Rentsendorj. S (Baatarkhuyag. A., Altantsetseg. D., 2015). The coal deposit is located in the center portion of the Nariinsukhait basin. The age of coal hosted sedimentary rock is Jurassic estimated by Paleo-botanic methodology, using examination of a total 59 kind of plants, 288 pollen grains (Baatarkhuyag. A., Altantsetseg. D., 2015). The thickness of coal hosted sedimentary sequence is approximately 1105.5m and named as Orgilohbulag formation. In case of geophysical exploration, preliminary interpretation of the coal basin has been done by 3 geophysical methodologies which commonly applying during exploration stage of coal. The interpretations are given below. Natural Gamma Sonde /NGRS 4140/: use to determine natural gamma activation on rock by radionuclides content (238U; 235U; 232Th; 40K). During measurements well contrasted coal bedding and, value indicate between 0-15cps. And depending on the rock type it has been changed, in case of siltstone, argillite, conglomerate value fluctuated between 15-40cps. However, those rocks natural gamma values are difference little, therefore not showing much contrast between rock types. Formation Density Sonde Version B /FDSB 4036/: The Nariinsukhait coal deposit Open holes and protective pipes of density is 0.5-1.5 g/cm3, 1.2-2.3 g/cm3 respectively. Not well contrasted during measurement due to some of sedimentary rock density range is so low as such sandstone, siltstone, and conglomerate. Therefore, applied resistivity methodology and done interpretation. DLL3

A paleoenvironmental study of subsurface Quaternary sediments at Wainuiomata, Wellington, New Zealand, and tectonic implications

International Nuclear Information System (INIS)

Begg, J.G.; Mildenhall, D.C.; Lyon, G.L.; Stephenson, W.R.; Funnell, R.H.; Van Dissen, R.J.; Bannister, S.; Brown, L.J.; Pillans, B.; Harper, M.A.; Whitton, J.

1993-01-01

A stratigraphic drillhole (WS-1) sited on the floor of Wainuiomata Valley near Lower Hutt, revealed a 61.6 m thick Quaternary sequence overlying Torlesse Supergroup greywacke sandstone and argillite. The Quaternary sediments consist of three sequences separated by disconformities. The lower sequence, 10.7 m thick (61.6-50.9 m), consists of fluvial sediments of probable early Quaternary age. The middle sequence, about 48.3 m in thickness (50.9-c. 2.6 m), spans most of the Last Glaciation. Fluvial/overbnak (50.9-42.0 m), floodplain/swamp (42.9-34.5 m), and fluvial (34.5-31.3 m) sediments overlie the disconformity at 50.9 m. Conformably overlying these sediments are swamp and lacustrine deposits between 31.3 and 4.1 m. Diatoms and algal spores and coenobia show the existence of an extensive lake during much of this sequence, from 25.6 to 4.0 m. at the peak of its development, at a drillhole depth of c. 23 m, the lake was >10 m deep and had a high algal biomass. Kawakawa Tephra (22 600 yr b.p.) occurs near the top of the middle sequence at 4.1 m depth. The upper sequence, of Holocene-Recent age, is <2.6 m thick, including .06 m of fill. The existence of sediments of the lower sequence of at least Castlecliffian age (early Pleistocene) uncomformably overlying basement greywacke provides a minimum age for the K-surface in the area. The Last Glacial sediments show evidence of ponfing, which may be a result of one factor or a combination of the following: ponding behind an aggradational terrace of the Wainuiomata River; landslide blockage of the Black Stream drainage near its confluence with Wainuiomata River; and tectonic deformation. Progressive tectonic deformation since about the start of the Last Glaciation is considered the most likely dominant factor. This has resulted in the elevation of greywacke basement near the junction of Black Stream and Wainuiomata River. The nature of the deformation - faulting, tilting, and/or folding - has not been established. (authors

Ultrasonic sounding and monitoring of the excavation damaged zone in a soft supported gallery

International Nuclear Information System (INIS)

Balland, Cyrille; Souley, Mountaka; Morel, Jacques

2012-01-01

gallery GCS (gallery with soft support and oriented parallel to the horizontal major stress) has predicted an extension of EDZ between 1.4 and 1.9 m according to the front advancement, the position around the gallery (roof, bottom and gallery side) and the rock characteristics. Moreover, a former experimentation showed that below the bottom of a gallery with this same orientation, ultrasonic velocity falls related to the damage were significant up to 2 m deep. The area of interest of experimentation OHZ encompasses at least this area with in addition one reference measurement in the undisturbed area. To escape heterogeneous variations of clay layers and the main anisotropy effect, two devices were selected with a triplet of horizontal drillings in the siding and a doublet of vertical drillings in the bottom of the gallery. P-wave tomographic data allowed rebuilding the images of the velocity on the 4 plans defined by the drillings. These images have shown a significant perturbation of the velocity field over 1.8 m deep in the gallery side. This area has been associated with the EDZ whose extension is of the same order of magnitude as which had been modeled during the blind predictions. Furthermore, there is an area of 0.4 m in depth on this siding with very low velocities or disappearance of ultrasonic rays in the 3 plans. That can be associated with fracturing of argillites. This very low velocity zone is not visible at the bottom, where velocity perturbations are much lower, with constant velocity over 1.6 m. The containment of the concrete floor, which is particularly thick at this location, might play a role in this observation. Finally, some anomalies of velocity are still visible beyond the end of the zone associated with the EDZ. They are probably caused by isolated fractures that occurred during excavation of the gallery and identified on extracted cores from the drillings. The magnitude of these anomalies would suggest that these fractures are closed. A program

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

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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

Contrasting styles of sedimentation and deformation in the Chugach Terrane accretionary complex, south-central Alaska

Science.gov (United States)

Amato, J. M.; Pavlis, T. L.; Worthman, C.; Kochelek, E.; Day, E. M.; Clift, P. D.; Hecker, J.

2011-12-01

In southeast Alaska the Chugach terrane represents an accretionary complex associated with several arcs active at 200-65 Ma. This lithostratigraphic unit consists of blueschists with Early Jurassic metamorphic ages and uncertain depositional ages; the Jurassic-Cretaceous McHugh Complex; and the Late Cretaceous Valdez Group. Detrital zircon ages from densely sampled transects reveals patterns in the assembly of the complex. Blueschists are almost totally barren of zircon, suggesting protoliths derived from mafic-intermediate volcanic protoliths far from a continental source. There is an age gap between the blueschists and the McHugh complex interpreted to be caused by an episode of tectonic erosion. The McHugh Complex is two separate units that are lithologically and geochronologically distinct. The older McHugh is a melange is dominated by stratally disrupted volcanic rocks, chert, and argillite. The oldest McHugh rocks have maximum depositional ages (MDA) of 177-150 Ma at Seldovia and 157-145 Ma at Turnagain Arm; the lack of older rocks at Turnagain Arm suggests removal of structural section by faulting. The MDAs of the older McHugh rocks do not decrease progressively away from the arc. There is a 45 m.y. gap in MDA between the older McHugh and the Late Cretaceous McHugh rocks. The younger McHugh rocks are dominated by volcanogenic sandstone and coarse conglomerate and MDA decreases from 100 Ma near the boundary with the older McHugh mesomelange to 85 Ma near the Valdez Group. The Valdez Group consists of coherently bedded turbidites with a MDA range of 85-60 Ma that decreases progressively outboard of the arc source. A sample from the Orca Group of the Prince William terrane is lithologically similar to the Valdez Group and there is no gap in MDA between Valdez and Orca Groups. 55 Ma dikes cut the McHugh and Valdez Groups in the western Chugach and Kenai Mountains. The oldest units of the Chugach terrane are the most deformed, with deformation and metamorphism

Kinematic analysis of mélange fabrics: examples and applications from the McHugh Complex, Kenai Peninsula, Alaska

Science.gov (United States)

Kusky, Timothy M.; Bradley, Dwight C.

1999-12-01

Permian to Cretaceous mélange of the McHugh Complex on the Kenai Peninsula, south-central Alaska includes blocks and belts of graywacke, argillite, limestone, chert, basalt, gabbro, and ultramafic rocks, intruded by a variety of igneous rocks. An oceanic plate stratigraphy is repeated hundreds of times across the map area, but most structures at the outcrop scale extend lithological layering. Strong rheological units occur as blocks within a matrix that flowed around the competent blocks during deformation, forming broken formation and mélange. Deformation was noncoaxial, and disruption of primary layering was a consequence of general strain driven by plate convergence in a relatively narrow zone between the overriding accretionary wedge and the downgoing, generally thinly sedimented oceanic plate. Soft-sediment deformation processes do not appear to have played a major role in the formation of the mélange. A model for deformation at the toe of the wedge is proposed in which layers oriented at low angles to σ1 are contracted in both the brittle and ductile regimes, layers at 30-45° to σ1 are extended in the brittle regime and contracted in the ductile regime, and layers at angles greater than 45° to σ1 are extended in both the brittle and ductile regimes. Imbrication in thrust duplexes occurs at deeper levels within the wedge. Many structures within mélange of the McHugh Complex are asymmetric and record kinematic information consistent with the inferred structural setting in an accretionary wedge. A displacement field for the McHugh Complex on the lower Kenai Peninsula includes three belts: an inboard belt of Late Triassic rocks records west-to-east-directed slip of hanging walls, a central belt of predominantly Early Jurassic rocks records north-south directed displacements, and Early Cretaceous rocks in an outboard belt preserve southwest-northeast directed slip vectors. Although precise ages of accretion are unknown, slip directions are compatible with

The influence of temperature and P/P0 upon cationic exchange constants

International Nuclear Information System (INIS)

Blanc, P.; Vieillard, P.; Gailhanou, H.; Gaboreau, S.; Gaucher, E.C.; Giffaut, E.

2010-01-01

Document available in extended abstract form only. The knowledge of thermodynamic properties of clay minerals forming clay materials is important in the context of a disposal within clayey formations (Callovo-Oxfordian argillite) or for clayey barriers. Different experiments have been previously performed concerning the long term behavior of clay materials, indicating that strong transformations are influenced by the alkaline solutions issued from the cementitious materials. But the first stages of the transformations affect the hydration and exchange capacity of the mineral, which are closely related to their retention properties. This work aims at assessing the influence of temperature and relative humidity upon the thermodynamic functions related to cationic exchange and hydration reactions. It is carried out within the framework of the Thermochimie project, aiming at defining a consistent thermodynamic database for modeling purposes. This work is an extension of the thermodynamic of hydration study carried out by Vieillard et al. (2010). Using the same, regular, solid solution model developed by the authors, we first consider the influence of temperature on the hydration reaction by expressing the hydration constant LogK hyd (T) according to the enthalpy and entropy of hydration and to the gas constant. Predicted isotherms are then compared with experimental data acquired on the MX80 smectite at 40, 60, 75, 90 and 100 deg. C. We now consider a cationic exchange reaction between cations A+ and B+, with z cations per mole of smectite and y2 and y1 mole of water per mole of smectite for A and B end members, respectively. The exchange constant LogK A/B , for a given temperature and relative humidity, is expressed as a function of the difference between anhydrous end members, and of the difference between anhydrous end-members activities. A comparison with room temperature exchange constants derived from experiments suggests that discrepancies are related to

Using restored cross sections to evaluate magma emplacement, White Horse Mountains, Eastern Nevada, U.S.A.

Science.gov (United States)

Marko, Wayne T.; Yoshinobu, Aaron S.

2011-03-01

New field observations and cross section restoration from the Jurassic White Horse pluton-host rock system, Goshute Range, eastern Nevada, USA, indicate a sequential variation of host rock rheology attending magma emplacement. The pluton intruded weakly to nondeformed Devonian-Mississippian limestone, argillite and quartzite at shallow crustal levels (ca. 7 km). The contact aureole is well exposed along the southern, eastern and northern margin of the intrusive body and is less than 1 km wide. Rocks outside of the aureole are sub-horizontal and do not contain a penetrative fabric or are gently folded (interlimb angles > 120°) about sub-vertical axial planes. Within the contact aureole, continuous and discontinuous spaced, axial planar foliations and harmonic to disharmonic, tight to isoclinal folds wrap around the eastern margin of the pluton. Folds verge toward and away from the pluton and rim anticlines, synclines, and monoclines with wavelength in excess of 250 m are preserved along the pluton margin. The spatial proximity of these ductile structures to the pluton and the apparent increase in intensity of structure development approaching the pluton is compatible with contraction within the aureole attending pluton emplacement. However, all of the above structures are truncated by the intrusive contact at various scales. Granodioritic dikes ranging in thickness from 1 m up to ˜ 10 m emanate from the intrusion and cut host rock structure at high angles and turn to propagate towards one another, parallel to the pluton margin and host rock anisotropy. Such features are interpreted to reflect the last stages of diking and brittle deformation that modified the pluton contact after emplacement-related folding of the carbonate rocks, but before final solidification of the pluton. Eight serial geologic cross sections were constructed and evaluated to place geometric constraints on the shape and growth of the White Horse intrusion. Based on line-length restoration of

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)

Blanchart, Pascale; Faure, Pierre; Michels, Raymond; Parant, Stephane

2012-01-01

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 CO 2 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

Mineralogy and geochemistry of two metamorphosed sedimentary manganese deposits, Sierra Nevada, California, USA

Science.gov (United States)

Flohr, M.J.K.; Huebner, J.S.

1992-01-01

Laminated to massive rhodochrosite, hausmannite, and Mn-silicates from the Smith prospect and Manga-Chrome mine, Sierra Nevada, California were deposited as ocean floor sediments associated with chert and shale. The principal lithologies at Smith are chert, argillite, rhodochrosite-, hausmannite- and chlorite-rich layers, and relatively uncommon layers of jacobsite. The Manga-Chrome mine also contains layers rich in manganoan calcite and caryopilite. Tephroite, rhodonite, spessartine, and accessory alleghanyite and sonolite formed during metamorphism. Volcaniclastic components are present at Manga-Chrome as metavolcanic clasts and as Mn-poor, red, garnet- and hematite-rich layers. There is no evidence, such as relict lithologies, that Mn was introduced into Mn-poor lithologies such as chert, limestone or mudstone. Replacement of Mn-poor phases by Mn-rich phases is observed only in the groundmass of volcanic clasts that appear to have fallen into soft Mn-rich mud. Manganiferous samples from the Smith prospect and Manga-Chrome mine have high Mn Fe and low concentrations of Ni, Cu, Zn, Co, U, Th and the rare-earth elements that are similar to concentrations reported from other ancient Mn deposits found in chert-greenstone complexes and from manganiferous sediments and crusts that are forming near modern sea floor vents. The Sierra Nevada deposits formed as precipitates of Mn-rich sediments on the sea floor, probably from mixtures of circulating hydrothermal fluids and seawater. The composition of a metabasalt from the Smith prospect is consistent with those of island-arc tholeiites. Metavolcanic clasts from the Manga-Chrome mine are compositionally distinct from the Smith metabasalt and have alkaline to calc-alkaline affinities. A back-arc basin is considered to be the most likely paleoenvironment for the formation of the Mn-rich lenses at the Manga-Chrome mine and, by association, the Smith prospect. Layers of rhodochrosite, hausmannite and chert preserve the

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

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

International Nuclear Information System (INIS)

Rebours, Herve; Righini, Celine

2010-01-01

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

The development condition of longitudinal channels of a Lower Cretaceous formation and its perspective for sandstone type uranium deposits in the Erlian basin, northern China

International Nuclear Information System (INIS)

Qin, M.; Xu, Q.; Liu, W.; Song, J.; Chen, D.; Wei, S.

2014-01-01

The palaeochannel, which is classified as basal and interformational types on the basis of geological setting, is an important host for the sandstone type uranium deposit. Diversities exist in development conditions and uranium minerogenetic potential of the two types of palaeochanneles. The Erlian basin, about 105 km"2 and adjacent to channel-type uranium deposit provinces in Russia and Mongolia, is one of main uraniferous basins in the north of China. It is significant to research into development conditions of palaeochannels for uranium mineral exploration in the Erlian basin. 1. Geological background: The Erlian basin consists of five depressions which divide the basin and form alternations with uplifts and depressions. Sedimentary capping strata of the basin mainly is the Lower Cretaceous Bayanhua group (K1b) which consists of the Aershan group (K1ba), Tenger group (K1bt) and Saihan group (K1bs) from bottom to top. The Saihan group, which is the product in the phase of depression, is the most important uranous strata in the Erlian basin. 2. Development characteristic and condition of the longitudinal palaeochannel of the Saihan formation: Large-scale longitudinal multi-palaeochannels are identified in the center and northeast of the basin, such as the QiHaRiGeTu-SaiHanGaoBi palaeochannel (CH01), BaYanWuLa palaeochannel (CH02) and GaoLiHan palaeochanne l(CH03), et al., which character the length from several 10s of km to 100 km, width of several 10s of km and thickness of sand bodies from 20 m to 130 m, more or less. Palaeochannels of the Saihan formation are interformational type because the underlay is argillite at the top of the Tenggeer formation. Restrictive geological environments and conditions are necessary to form longitudinal channels and mainly are as follows: (1) the basin in the sustained step of depression; (2) sharp gradient (>5°?) in parts of sub-depressions and sufficient sedimentary supply from the upstream; (3) elongate erosional lowlands or

Metallogeny of The Sierra de Guanajuato Range, Central México

Science.gov (United States)

Pedro F., Z. D.

2004-12-01

The Sierra de Guanajuato Range (SGR), trending N315° at Central México, is an orographic feature extending over a distance of 80 km. SGR comprises three well defined lithostratigraphic units: (1) a cretaceous basement including an arc-derived terrane named Guanajuato Arc (GA) made of gabbro, diorite and basaltic pillowed lava, and volcano-sedimentary rocks belonging to Arperos fore-arc basin which are geochemically anomalous in Au (0.15 ppm), Ag (3 ppm), Cu (40 ppm), Pb (50 ppm) and Zn (15 ppm); (2) Early Tertiary intrusive rocks, e.g., Comanja Granite which is affected by the presence of tourmalinized (schörl) aplito-pegmatite dykes mineralized with rare earths elements, and (3) Eocene redbeds (1,500-2000 m) and Oligocene-Miocene volcanics cover. The metallogeny of the SGR shows a multiple origin in time and space: volcano-sedimentary, granitic and volcanic, being possible to define three metallogenic epochs: cretaceous, paleocene and oligocene. Cretaceous epoch includes: (a) volcanogenic massive sulphide deposits (VMS) of bimodal-siliclastic type belonging to León-Guanajuato district; wallrock of VMS is made of felsic-internediate volcanics and black argillite; at Los Gavilanes deposit paragenesis is next: chalcopyrite > sphalerite > galena, pyrite > pyrrhotite > marcasite; grade is as follows: Au: .02-.07 g/t; Ag: 157-18.5 g/t; Cu: 2.24-0.81%, Pb: 4.16-0.03%; Zn: 10.35-3.02 %; (b) lens-shaped stratiform bodies of massive pyrite (i. ex., San Ignacio prospect; ˜ 4,000 ton) of exhalative-sedimentary origin with chalcopyrite and sphalerite microveins. Paleocene epoch includes both quartz-cordierite-sanidine veins and replacement bodies of hydrothermal metamorphic filliation (W +Se-Bi, Pb, Zn, Cu), and pyrometasomatic bodies [Cu, Pb, Zn (Ag), W] which genetically are linked to Comanja Granite emplacement. The wallrock at El Maguey mine (35,000 ton; 0.6% WO3) is made of hornfel and the vein (1.8-3.2m width) has a banding structure made of : \\{quartz & K

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)

Landais, Patrick

2013-01-01

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

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

2014-01-01

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

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

International Nuclear Information System (INIS)

Bosgiraud, Jean-Michel; Delort, Daniel

2015-01-01

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

Thermodynamics of hydration of MX80-Na. What are the best approaches for evaluating the thermodynamic properties of hydration?

International Nuclear Information System (INIS)

Vieillard, P.; Lassin, A.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Gaucher, E.C.; Denoyel, R.; Bloch, E.; Fialips, C.; Giffaut, E.

2012-01-01

Document available in extended abstract form only. In the context of a waste disposal within clayey formations (Callovian-Oxfordian argillite) or using clayey barriers, the prediction of the long-term behavior requires the thermodynamic properties of clay minerals. It has been shown by Gailhanou et al. (submitted) that hydration reactions may have some dramatic consequences on the thermodynamic properties of clay minerals. Different theoretical models exist for extracting thermodynamic properties from water adsorption/desorption isotherms. The present work aims at investigating and comparing these methods, because they can provide very different results based on the assumptions of each models. First, three types of models are compared: 1) the Hill (1949) model based on heat of adsorption combined with adsorption isotherm, 2) the Jura and Hill (1951) model, based on the Clausius-Clapeyron relation, and 3) the BET theory. Both have been designed in order to describe surface sorption phenomena. For instance, they suppose that the number of sorption sites is constant during all the vapor sorption process (and at any relative humidity, P/P 0 ). The hydration reaction approach can also be used. Compared to the three previous models, it is not structurally constrained, except for mass balance considerations on the H 2 O component. It had been especially developed by Tardy and Touret, (1985) and modified into a solid solution model, first by Ransom and Helgeson, (1994). It relies simply on the reaction: Clay(dehydrated) + nH 2 O = Clay(hydrated).nH 2 O. The different families of models have been compared to experimental measurements performed on a sodic smectite MX80. The set of experiments includes a series of three adsorption/desorption isotherms obtained at 25, 45 and 60 C and a heat of adsorption combined with a adsorption isotherm obtained at 25 C. The heat of adsorption was derived from the 3 adsorption/desorption isotherms by using the different models. Then

Conditioning of traced rock section for diffusion profile analyses

International Nuclear Information System (INIS)

Dewonck, S.; Auriere, C.

2010-01-01

Document available in extended abstract form only. The French National Agency for radioactive waste management investigates for a high-level radioactive waste repository in deep geological formation. The Andra's disposal concept is based notably on the impermeable properties of the host rock barrier (the Callovo-Oxfordian mud-stone of the Eastern Paris Basin). Diffusion is assumed to be the main transport mechanism governing radionuclide migration through argillite. Diffusion properties were measured in situ, in the constrained rock, by experiments taken place at the Andra's Underground Research Laboratory. The diffusion experiments consist in injecting a traced solution as pulse, in a packed-off borehole interval, at a pressure similar of the hydraulic pressure of the rock. After several months of circulation, the traced solution is purged and the downhole equipment is dismantled. With a drilling machine, the overcoring of the rock section around the injection interval is performed to analyze the repartition of the radionuclides in the clay section. Totally new technical developments were necessary to make these tasks possible. This contribution reports on: - the method developed to going up the over-core from the gallery to the surface without damaging the traced clay section and avoiding any contamination of the underground installation by dust particles, - the specific room created to sampling the rock section in diffusion profiles with respect of radioprotection laws. In gallery, the over-core is extracted from the core barrel directly to a metallic box especially built to transport the clay section to the surface. This box is a good confining device avoiding all radioactive contamination of the galleries and the shaft. Moreover, this box made in iron decrease the dose equivalent rate and consecutively it's not necessary to have safety classification to transport the core. When the over-core is in the radioactive cutting room, technicians have

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

Energy Technology Data Exchange (ETDEWEB)

Javeri, V.; Le, T.T.; Cui, Y.J.; Delage, P.; Li, X.J.; Wieczorek, K.; Jockwer, N.; Romero, E.; Lima, A.; Gens, A.; Li, X.L.; Francois, B.; Nuth, M.; Laloui, L.; Chen, W.; Jia, S.; Yu, H.; Wu, G.; Li, X.; Bernier, F.; Tan, X.; Wu, G.; Jia, S.; Giot, R.; Hoxha, D.; Giraud, A.; Homand, F.; Su, K.; Chavant, C.; Duveau, G.; Jia, Y.; Shao, J.F.; Peron, H.; Laloui, L.; Hueckel, T.; Hu, L.B.; Auvray, C.; Lequiller, B.; Cuisinier, O.; Ferber, V.; Cui, Y.J.; Deneele, D.; Uhlig, L.; Jobmann, M.; Polster, M.; Vaunat, J.; Garrite, B.; Wileveau, Y.; Sato, H.; Jacinto, A.; Sanchez, M.; Ledesma, A.; Morel, J.; Balland, C.; Armand, G.; Nguyen Minh, D.; Vales, F.; Pham, Q.T.; Gharbi, H.; Mokni, N.; Olivella, S.; Li, X.; Smets, St.; Valcke, E.; Karnland, O.; Nilsson, U.; Olsson, S.; Sellin, P.; Fernandez, A.M.; Melon, A.M.; Villar, M.V.; Turrero, M.J.; Garitte, B.; Guimaraes, L.D.N.; Gens, A.; Mayor, J.C.; Koliji, A.; Laloui, L.; Vulliet, L.; Hamdi, N.; Marzouki, A.; Srasra, E.; Cuss, R.J.; Harrington, J.F.; Noy, D.J.; Birchall, D.J.; Marschall, P.; Mallet, A.; Ababou, R.; Matray, J.M.; Renaud, V.; Maison, T.; Enachescu, C.; Frieg, B.; Rohs, St.; Paris, B.; Robinet, J.C.; Bui, T.D.; Barnichon, J.D.; Plas, F.; Klubertanz, G.; Folly, M.; Hufschmied, P.; Frank, E

2007-07-01

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

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

International Nuclear Information System (INIS)

Libert, M.; Esnault, L.

2010-01-01

-Oxfordian will support sulfate reducing bacteria or methanogen bacteria. Iron reducing activity could develop near containers or in argillite. Several examples and results of kinetic of H 2 consumption by microorganisms are here presented: - The development of bacteria using oxygen and H 2 from radiolysis of water in basin containing irradiating waste. The development of denitrifying bacteria using nitrates and H 2 in the environment of bituminized embedded waste. In presence of H 2 , 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 H 2 from container corrosion products. Shewanella sp is able to oxidise 1.2 mmoles of H 2 /day by iron reduction. The consequences of the development of H 2 oxidising bacteria are discussed in terms of physico-chemical modifications in geological disposal: biomass production, gas production and consumption, bio-corrosion

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

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

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)

Claret, F.; Marty, N.C.M.; Tournassat, C.; Gaboreau, S.; Burnol, A.; Chiaberge, C.; Gaucher, E.C.; Munier, I.; Cochepin, B.; Michau, N.

2010-01-01

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 TECPLOT R . 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

Magmatism and Tectonics in the Meso-Archean Pongola Supergroup, South Africa

Science.gov (United States)

Wilson, Allan

2013-04-01

The Pongola Supergroup is one of the most extensive and well preserved volcano-sedimentary successions emplaced in a continental setting in the Meso-Archean (c. 2.95 Ga). It contrasts with both the older (Barberton type c.3.5 Ga) and younger (Belingwe type c.2.7 Ga) greenstone belts in southern Africa in that the sequence has not undergone the strong horizontal compressional tectonics typically related to greenstone belt-TTG environments. However, it is appropriate to compare this sequence with rocks of the Barberton greenstone belt by which the final phase of deposition preceded that of the juxtaposed Pongola basin with a relatively small time interval. The Pongola succession, which commenced with the first major magmatic event after the Barberton greenstone belt, overlies granitoids and remnants of greenstone belts in SE South Africa and in SW Swaziland. Formation was not in a continental rift environment but most likely in a marginal epicontinental basin with syn-depositional subsidence in a half-graben fault system in the type area. The Pongola rocks occur in two domains related to a NW-trending central basement high in the Kaapvaal Craton and achieving a maximum thickness of 8 km in the northern areas. The lower section (Nsuze group 3.7 km thick) is made up mainly of lavas and pyroclastic rocks and the upper section (Mozaan Group 4.3 km thick) is aranaceous sediments and argillites with a thick volcanic unit observed in the south-eastern facies. Chemical affinities of the lavas include tholeiite and calc-alkaline over the compositional range of basalt to rhyolite. There is a preponderance of andesites in the compositional array. The preservation of these rocks gives insight into the range of volcanic processes that took place at this stage of Earth history and in some areas it is possible to identify eruptions from a single source over several kilometres, as well as feeder-dyke systems to the lava flows. Simultaneous eruption of contrasting magmas from several

Abiotic nitrate and sulphate reduction by hydrogen: a comparative experimental study

International Nuclear Information System (INIS)

Truche, L.; Berger, G.; Albrecht, A.; Giffaut, E.

2010-01-01

Document available in extended abstract form only. The bituminous waste which is part of the intermediate level, long-lived waste (MAVL) is characterised, amongst others, by the coexistence of nitrates, sulphates, organic matter, native metals and hydrogen gas in the waste mixture and package. It can be considered as the most complex example that will be used to discuss redox reactions occurring in such waste mixtures. The evaluation of the redox conditions requires quantification of the amount of electron acceptors and donors and definition of the kinetics of redox reaction. The objectives of an experimental study to unravel some of these reaction complexities are: - to investigate nature and rate of sulphate and nitrate reduction by hydrogen in the presence of different catalysts (stainless steel, hastelloy, magnetite and argillite); - to compare sulphate and nitrate as electron acceptors; - to provide a mechanistic model of these reactions. It is well known that reduction of sulphate and nitrate requires high activation energies, usually supplied either by thermal processes or via bacterial and surface catalysis, of which the latter has been investigated in this study. Preliminary experiments performed at 150 deg. C and under H 2 pressure show that sulphate reduction is enhanced in the presence of magnetite, but essentially under the restricted condition of low sulphate concentration and at a pH below the Point of Zero Charge of magnetite. This suggests that sorption of sulphate contributes to the catalysed reaction (at low pH) but provided that the magnetite surface sites are not saturated with respect to aqueous sulphate (low concentration). On the contrary, nitrate reduction is observed whatever the pH and the nitrate concentration in the presence of both magnetite and hastelloy C276 (Ni, Cr, Mo, W, Fe alloy). The effect of temperature on the rate of nitrate reduction (500 ppm KNO 3 solution) is shown by comparing three different experiments conducted in

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

Fractionation between inorganic and organic carbon during the Lomagundi (2.22 2.1 Ga) carbon isotope excursion

Science.gov (United States)

Bekker, A.; Holmden, C.; Beukes, N. J.; Kenig, F.; Eglinton, B.; Patterson, W. P.

2008-07-01

The Lomagundi (2.22-2.1 Ga) positive carbon isotope excursion in shallow-marine sedimentary carbonates has been associated with the rise in atmospheric oxygen, but subsequent studies have demonstrated that the carbon isotope excursion was preceded by the rise in atmospheric oxygen. The amount of oxygen released to the exosphere during the Lomagundi excursion is constrained by the average global fractionation between inorganic and organic carbon, which is poorly characterized. Because dissolved inorganic and organic carbon reservoirs were arguably larger in the Paleoproterozoic ocean, at a time of lower solar luminosity and lower ocean redox state, decoupling between these two variables might be expected. We determined carbon isotope values of carbonate and organic matter in carbonates and shales of the Silverton Formation, South Africa and in the correlative Sengoma Argillite Formation, near the border in Botswana. These units were deposited between 2.22 and 2.06 Ga along the margin of the Kaapvaal Craton in an open-marine deltaic setting and experienced lower greenschist facies metamorphism. The prodelta to offshore marine shales are overlain by a subtidal carbonate sequence. Carbonates exhibit elevated 13C values ranging from 8.3 to 11.2‰ vs. VPDB consistent with deposition during the Lomagundi positive excursion. The total organic carbon (TOC) contents range from 0.01 to 0.6% and δ13C values range from - 24.8 to - 13.9‰. Thus, the isotopic fractionation between organic and carbonate carbon was on average 30.3 ± 2.8‰ ( n = 32) in the shallow-marine environment. The underlying Sengoma shales have highly variable TOC contents (0.14 to 21.94%) and δ13C values (- 33.7 to - 20.8‰) with an average of - 27.0 ± 3.0‰ ( n = 50). Considering that the shales were also deposited during the Lomagundi excursion, and taking δ13C values of the overlying carbonates as representative of the δ13C value of dissolved inorganic carbon during shale deposition, a carbon

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

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

Considering clay rock heterogeneity in radionuclide retention

International Nuclear Information System (INIS)

Grambow, B.; Montavon, G.; Tournassat, C.; Giffaut, E.; Altmann, S.

2010-01-01

considering the measured mass fraction of illite, I/S, and kaolinite. Five values were fitted simultaneous in the overall fit: the CECs of the kaolinite, the smectite and illite components as well as the illite fraction in both R0 and R1 I/S. For transport calculations of radionuclides it is important to know which part of the overall porosity belongs to the micropores and which to the interlayers of the smectite layers in the inter-stratified I/S. Making the hypothesis that, at the given degree of compaction, these interlayers are hydrated by two water layers one could calculate the fraction of micropores in total porosity from the measured I/S content and the fitted I/S ratio given for either R0 or R1. For high smectite contents there is about twice as much water in interlayers than in the micropores, while there is much more water in the micropores in case of low smectite contents. The retention and porosity models for Bentonite have been adapted successfully to argillite samples for various drill cores assuming additivity of the various mineralogical contributions, in particular illite and I/S and of the illite to smectite ratio in I/S. The approach leads to a reasonable quantitative representation of the CEC as well as of surface complexation site densities as a function of depth and mineralogical composition. Ratios of micropores to interlayer pore space were obtained as well. The good correlation of calculated and measured retention data for Cs and for Ni gave reasonable justification to apply the model for the prediction of K d variations of Cs all along a drill core. Predicted values vary by about a factor of 10. (authors)

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)

Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

2010-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were

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

International Nuclear Information System (INIS)

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

2010-01-01

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

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

International Nuclear Information System (INIS)

Malinsky, Laurent; Talandier, Jean

2012-01-01

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

Evidence From Detrital Zircon U-Pb Analysis for Suturing of Pre-Mississippian Terranes in Arctic Alaska

Science.gov (United States)

Moore, T. E.; Potter, C. J.; O'Sullivan, P. B.; Aleinikoff, J. N.

2007-12-01

Detrital zircon U-Pb ages of pre-Mississippian sandstones were determined using SHRIMP and LA-ICPMS techniques for four key geographic parts of the Arctic Alaska terrane, northern Alaska. In the northeastern Brooks Range, a sample of quartz-rich turbidites from the Proterozoic Neroukpuk Quartzite yielded zircon ages ranging from 980 Ma to 2.9 Ga with clusters at 980-1100 Ma, 1680-1850 Ma and 2220-2660 Ma. Quartz and chert-bearing sandstone in the Tulageak well from Ordovician-Silurian argillite in basement beneath the North Slope yielded a broad spectrum of ages between 1.0 to 2.1 Ga and 2.8 Ga, including peaks at 1.0-1.2 and 1.5-1.7 Ga. Paleozoic zircons cluster at 390 and 440 Ma in this sample, indicating it is Devonian. Lithic sandstone from the Silurian Iviagik Group at Cape Dyer on the Lisburne Peninsula yielded a variety of ages from 450 to 1600 Ma, with a large peak at 475-600 Ma and several grains between 1.9 and 2.5 Ga. In contrast to the broad distributions of the latter two samples, zircons in metamorphosed Proterozoic-Cambrian(?) lithic sandstone from the an unnamed metagraywacke unit near Mt. Snowden on the Dalton Highway in the southern Brooks Range are largely 600-650 Ma with lesser clusters at 1050-1200 Ma and 1600-1900 Ga. Samples of quartz-rich Mississippian sandstone at the base of the unconformably overlying Mississippian to Triassic Ellesmerian sequence near three of the pre-Mississippian sample locations were also analyzed. Mississippian sandstones from the West Dease well (near the Tulageak well) and at Cape Dyer on the Lisburne Peninsula display zircon distributions similar to those found in the underlying pre-Mississippian samples, indicating the Mississippian clastic strata are locally derived and that the observed zircon distributions are representative of a broad area. However, the Mississippian Kekiktuk Conglomerate, which rests on the Neroukpuk Quartzite in the northeastern Brooks Range, also contains a variety of ages between 560 and

Geology of quadrangles H-12, H-13, and parts of I-12 and I-13, (zone III) in northeastern Santander Department, Colombia

Science.gov (United States)

Ward, Dwight Edward; Goldsmith, Richard; Cruz, Jaime B.; Restrepo, Hernan A.

1974-01-01

A program of geologic mapping and mineral investigation in Colombia was undertaken cooperatively by the Colombian Instituto Nacional de Investigaciones Geologico-Mineras (formerly known as the Inventario Minero Nacional), and the U. S. Geological Survey; by the Government of Colombia and the Agency for International Development, U. S. Department of State. The purpose was to study, and evaluate mineral resources (excluding of petroleum, coal, emeralds, and alluvial gold) of four selected areas, designated Zones I to IV, that total about 70,000 km2. The work in Zone III, in the Cordillera Oriental, was done from 1965 to 1968. The northeast trend of the Cordillera Oriental of Colombia swings abruptly to north-northwest in the area of this report, and divides around the southern end of the Maracaibo Basin. This section of the Cordillera Oriental is referred to as the Santander Massif. Radiometric age determinations indicate that the oldest rocks of the Santander massif are Precambrian and include high-grade gneiss, schist, and migmatite of the Bucaramanga Formation. These rocks were probably part of the Precambrian Guayana Shield. Low- to medium-grade metamorphic rocks of late Precambrian to Ordovician age .include phyllite, schist, metasiltstone, metasandstone, and marble of the Silgara Formation, a geosynclinal series of considerable extent in the Cordillera Oriental and possibly the Cordillera de Merida of Venezuela. Orthogneiss ranging from granite to tonalite is widely distributed in the high- and medium-grade metamorphic rocks of the central core of the massif and probably represents rocks of two ages, Precambrian and Ordovician to Early Devonian. Younger orthogneiss and the Silgara are overlain by Middle Devonian beds of the Floresta Formation which show a generally low but varying degree of metamorphism. Phyllite and argillite are common, and infrequent marble and other calcareous beds are fossiliferous. Except for recrystallization in limestones of !the

In situ determination of anisotropic permeability of clay

International Nuclear Information System (INIS)

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

2010-01-01

Document available in extended abstract form only. Clay stone has, due to its tectonic evolution of the formation, hydraulically and mechanically transversal isotropic behaviour. Argillite bedding or layering structure has been observed in the underground laboratories Mont Terri in Switzerland and Meuse/Haute-Marne at Bure site in France. To characterise the hydraulic properties of the clay formation, single and double packer systems have been applied based on the packer test theory. However, this kind of packer type cannot distinguish the difference between the properties parallel to the bedding and perpendicular to the bedding. The previous investigations using single packer system in boreholes parallel and perpendicular to bedding show quite different pressure decrease rates. The measured pressure development serves for the determination of the hydraulic parameters, which however may also be influenced by pore water pressure in partially or fully saturated medium, like clay stone. In order to filter out this influence, the measurements should be made at the same location in the same borehole. Therefore a 'slot packer' system has been developed to measure hydraulic properties in dependency of bedding direction. An intensive test program has been carried out in the Mont Terri Rock Laboratory to judge the feasibility of the new packer system for the hydraulic anisotropy characterisation before the packer will be applied in the French Underground Laboratory Meuse/Haute-Marne. One important issue of the test program is to get the feeling of the packer handling and technical features. Three campaigns in 2007 and four campaigns in 2008 have been carried out. Seven boreholes with length from 3 to 10 metres have been drilled for the test purpose. The long boreholes with a length of ten metres are originally planned for intensive testing in the undisturbed zone, the short holes for the near-field characterisation. The disturbed zone around an underground opening

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)

Bourdoiseau, Jacques-Andre

2011-01-01

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 FeCO 3 , 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 Fe 3 S 4 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

Carbonate rocks of the Seward Peninsula, Alaska: Their correlation and paleogeographic significance

Science.gov (United States)

Dumoulin, Julie A.; Harris, Alta; Repetski, John E.

2014-01-01

associated calcareous metaturbidites of Ordovician age as well as shallow-water Silurian dolostones. Scattered metacarbonate rocks are chiefly Cambrian, Ordovician, Silurian, and Devonian dolostones that formed in shallow, warm-water settings with locally restricted circulation and marbles of less constrained Paleozoic age. Carbonate metaturbidites occur on the northeast and southeast coasts and yield mainly Silurian and lesser Ordovician and Devonian conodonts; the northern succession also includes debris flows with meter-scale clasts and an argillite interval with Late Ordovician graptolites and lenses of radiolarian chert. Mafic igneous rocks at least partly of Early Devonian age are common in the southern succession. Carbonate rocks on Seward Peninsula experienced a range of deformational and thermal histories equivalent to those documented in the Brooks Range. Conodont color alteration indices (CAIs) from Seward Peninsula, like those from the Brooks Range, define distinct thermal provinces that likely reflect structural burial. Penetratively deformed high-pressure metamorphic rocks of the Nome Complex (CAIs ≥5) correspond to rocks of the Schist belt in the southern Brooks Range; both record subduction during early stages of the Jurassic–Cretaceous Brooks Range orogeny. Weakly metamorphosed to unmetamorphosed strata of the York terrane (CAIs mainly 2–5), like Brooks Range rocks in the Central belt and structural allochthons to the north, experienced moderate to shallow burial during the main phase of the Brooks Range orogeny. The nature of the contact between the York terrane and the Nome Complex is uncertain; it may be a thrust fault, an extensional surface, or a thrust fault later reactivated as an extensional fault. Lithofacies and biofacies data indicate that, in spite of their divergent Mesozoic histories, rocks of the York terrane and protoliths of the Nome Complex formed as part of the same lower Paleozoic carbonate platform. Stratigraphies in both

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

International Nuclear Information System (INIS)

Fernandez, A.M.

2010-01-01

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

Two-scale modelling for hydro-mechanical damage

International Nuclear Information System (INIS)

Frey, J.; Chambon, R.; Dascalu, C.

2010-01-01

solid conservation is achieved following the skeleton during the movement and finally the balance equation of the fluid is achieved at the microstructure scale. The non-linear problem is solved using a Newton- Raphson iteration process, in order to compute the resulting linearized system, all the needed quantities, namely the stress of the mixture, the density, the fluid mass flow, the fluid mass variation and linearization of those, are resulting from the microstructure analysis. At the microscopic scale, fluid and solid phase are described explicitly. Granular geometry is used for the R.E.V. Grains are modelled using large strain (hyper) elastic law, separated by micro-cracks filled by fluid. The fracture process of these cracks, at the interfaces between each grain, is modelled by a cohesive law. To perform the analysis on the microstructure, boundaries conditions, resulting from the macroscopic level, are applied on the R.E.V.: - Linear or periodic displacement are computed using a macroscopic gradient of deformation. - Linear or periodic boundary pressures are computed using both a macroscopic gradient of pressure and an average pressure. This two-scale method gives us a numerical law to describe complex hydro-mechanic damage process at the microstructure scale. Complex morphologies, like quartz inclusion in the argillite matrix, are considered. The reciprocal influence damage-permeability is studied numerically. (authors)

Probing Fe (III)/Fe (II) redox potential in a clayey material

International Nuclear Information System (INIS)

Tournassat, Christophe; Chainet, Fabien; Betelu, Stephanie; Hadi, Jebril; Gaucher, Eric C.; Ignatiadis, Ioannis; Greneche, Jean-Marc; Charlet, Laurent

2010-01-01

Document available in extended abstract form only. Redox is one of the main factors affecting the migration of redox-sensitive radionuclides. As a consequence reducing conditions are considered of strategic importance for the confinement properties of a clayey formation towards nuclear waste. A representative redox potential of clay formation such as Callovian- Oxfordian (COx) can be derived from thermodynamic calculations considering equilibrium between observed redox phases such as pyrite and siderite. However, there is little information on the reactivity of the different reservoirs of redox constituents in this type of complex material. The present study aims at investigating the reactivity of the Fe(III)/Fe(II) redox couple in the structure of clay minerals using different investigation methods: electrochemistry and O 2 reduction kinetic experiments. Clay modified electrodes were specifically designed to probe Fe(III)/Fe(II) redox potential in the structure of clay minerals. The clay fraction of a Callovian-Oxfordian argillite sample originating from the same level than ANDRA underground research laboratory was used after pre-treatment to remove organic matter and accessory minerals such as pyrite that could influence redox potential measurements. These electrodes were used to verify the validity of the model of Favre et al. (2006) that links the redox potential (E clay ) to the the Fe(II)/Fe tot ratio in the structure (m rel ), the pH and the sodium concentration in solution: equation 1. The good agreement between direct potential measurements and model prediction provides a strong evidence of the relevance of this model in our experimental conditions although the clay composition and its too low Fe content do not a priori fulfil the conditions set by Drits and Manceau (2000) for the calculation of K 0 parameter. Following the verification of the model, we tried to apply it to the specific case of a Callovian-Oxfordian sample that had been very well preserved

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

International Nuclear Information System (INIS)

Chautard, C.; Mifsud, A.; Libert, M.; Marsal, F.

2012-01-01

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)

Ordovician and Silurian Phi Kappa and Trail Creek formations, Pioneer Mountains, central Idaho; stratigraphic and structural revisions, and new data on graptolite faunas

Science.gov (United States)

Dover, James H.; Berry, William B.N.; Ross, Reuben James

1980-01-01

Recent geologic mapping in the northern Pioneer Mountains combined with the identification of graptolites from 116 new collections indicate that the Ordovician and Silurian Phi Kappa and Trail Creek Formations occur in a series of thrust-bounded slices within a broad zone of imbricate thrust faulting. Though confirming a deformational style first reported in a 1963 study by Michael Churkin, our data suggest that the complexity and regional extent of the thrust zone were not previously recognized. Most previously published sections of the Phi Kappa and Trail Creek Formations were measured across unrecognized thrust faults and therefore include not only structural repetitions of graptolitic Ordovician and Silurian rocks but also other tectonically juxtaposed lithostratigraphic units of diverse ages as well. Because of this discovery, the need to reconsider the stratigraphic validity of these formations and their lithology, nomenclature, structural distribution, facies relations, and graptolite faunas has arisen. The Phi Kappa Formation in most thrust slices has internal stratigraphic continuity despite the intensity of deformation to which it was subjected. As revised herein, the Phi Kappa Formation is restricted to a structurally repeated succession of predominantly black, carbonaceous, graptolitic argillite and shale. Some limy, light-gray-weathering shale occurs in the middle part of the section, and fine-grained locally pebbly quartzite is present at the base. The basal quartzite is here named the Basin Gulch Quartzite Member of the Phi Kappa. The Phi Kappa redefined on a lithologic basis represents the span of Ordovician time from W. B. N. Berry's graptolite zones 2-4 through 15 and also includes approximately 17 m of lithologically identical shale of Early and Middle Silurian age at the top. The lower contact of the formation as revised is tectonic. The Phi Kappa is gradationally overlain by the Trail Creek Formation as restricted herein. Most of the coarser

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

International Nuclear Information System (INIS)

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

2008-03-01

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

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

Reconnaissance geologic map of the Hyampom 15' quadrangle, Trinity County, California

Science.gov (United States)

Irwin, William P.

2010-01-01

The Hyampom 15' quadrangle lies west of the Hayfork 15' quadrangle in the southern part of the Klamath Mountains geologic province of northern California. It spans parts of four generally northwest-trending tectono- stratigraphic terranes of the Klamath Mountains, the Eastern Hayfork, Western Hayfork, Rattlesnake Creek, and Western Jurassic terranes, as well as, in the southwest corner of the quadrangle, a small part of the Pickett Peak terrane of the Coast Range province. Remnants of the Cretaceous Great Valley overlap sequence that once covered much of the pre-Cretaceous bedrock of the quadrangle are now found only as a few small patches in the northeast corner of the quadrangle. Fluvial and lacustrine deposits of the mid-Tertiary Weaverville Formation crop out in the vicinity of the village of Hyampom. The Eastern Hayfork terrane is a broken formation and m-lange of volcanic and sedimentary rocks that include blocks of chert and limestone. The chert has not been sampled; however, chert from the same terrane in the Hayfork quadrangle contains radiolarians of Permian and Triassic ages, but none clearly of Jurassic age. Limestone at two localities contains late Paleozoic foraminifers. Some of the limestone from the Eastern Klamath terrane in the Hayfork quadrangle contains faunas of Tethyan affinity. The Western Hayfork terrane is part of an andesitic volcanic arc that was accreted to the western edge of the Eastern Hayfork terrane. It consists mainly of metavolcaniclastic andesitic agglomerate and tuff, as well as argillite and chert, and it includes the dioritic Ironside Mountain batholith that intruded during Middle Jurassic time (about 170 Ma). This intrusive body provides the principal constraint on the age of the terrane. The Rattlesnake Creek terrane is a melange consisting mostly of highly dismembered ophiolite. It includes slabs of serpentinized ultramafic rock, basaltic volcanic rocks, radiolarian chert of Triassic and Jurassic ages, limestone containing

Reconnaissance Geologic Map of the Hayfork 15' Quadrangle, Trinity County, California

Science.gov (United States)

Irwin, William P.

2010-01-01

Hayfork terrane is a broken formation and melange of volcanic and sedimentary rocks, including chert and blocks of amphibolite, limestone, and serpentinized ultramafic rocks. The chert contains radiolarians of Permian and Triassic ages, but none of clearly Jurassic age. In contrast, the cherts of the North Fork terrane contain Early and Middle Jurassic radiolarians in addition to those of Permian and Triassic ages; also, some limestones of the Eastern Hayfork terrane contain fossil faunas of Tethyan affinity, but those of the North Fork terrane do not. The Western Hayfork terrane is an andesitic volcanic arc that was accreted to the Eastern Hayfork terrane. It consists mainly of metavolcaniclastic andesitic agglomerate and tuff, as well as argillite and chert, and it includes the dioritic Ironside Mountain batholith, which intruded during Middle Jurassic time. Two large patches of Western Hayfork terrane mapped in the central part of the Eastern Hayfork terrane may be exposed through windows in the Eastern Hayfork terrane, although the structural relation is not clear. The Rattlesnake Creek terrane is a melange that occupies only a small area in the southwest corner of the Hayfork quadrangle; however, it is a major unit in the Hyampom 15' quadrangle to the west. It consists mainly of broken and sheared ophiolitic rocks of probable Permian or early Mesozoic age. The Cretaceous Great Valley sequence overlap assemblage here postdates the Early Cretaceous (approximately 136 Ma) emplacement of the Shasta Bally batholith, which is widely exposed to the east in the Weaverville 15' quadrangle. The Great Valley sequence once covered much of the southern Klamath Mountains; however, in the Hayfork quadrangle, only three small patches remain near its southern boundary. Weakly consolidated nonmarine sedimentary rocks of the Weaverville Formation of mid-Tertiary age, which contain abundant fossil plants, occupy a large, shallow, east-northeast-trending graben

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

Reabilitation of degraded area by erosion, using soil bioengineering techniques in Bacanga river basin, Sao Luis City - Maranhao State, Brazil.

Science.gov (United States)

Teixeira Guerra, A. J.; Rodrigues Bezerra, J. F.; da Mota Lima, L. D.; Silva Mendonça, J. K.; Vieira Souza, U. D.; Teixeira Guerra, T.

2009-04-01

The aim of this paper is to assess the stages of rehabilitation of a degraded site by erosion, in Salina/Sacavém district, São Luís City, considering geomorphologic characteristics and soil bioengineering techniques. This technique has been applied in different situations to rehabilitate degraded areas, with positive results from the use of biodegradable materials (e.g. vegetal fibres, wooden stakes and re-vegetation). These techniques stabilize the soil at low cost and improve the environment. Bioengineering involves the planned and strategic application of selected materials, involving biodegradable materials, often in combination with 'hard engineering' structures constructed from stone, concrete and steel. The settlement of São Luís was established in 1612 and has evolved in distinct phases. Rapid urban growth was associated with industrialization in the second half of the 18th Century. Rapid population and urban growth has intensified problems, compounded by poor planning and improper soil use. São Luís, like many other Brazilian cities, has experienced rapid population growth in recent decades, which has created a series of socio-economic and environmental problems, including accelerated soil erosion. Sacavém is one of these communities where natural and human factors contribute to the severe gully erosion. The local lithology is mainly Tertiary sandstones and, to a lesser extent, shales, argillites and siltstones, all of which belong to the Barreiras Formation. Weathering on these rocks produces erodible soils, including lithosols, latosols, concretionary red/yellow clay soils and concretionary plinthosols. Thus, erodible soils and regolith are subject to high erosion rates, especially on steeper slopes subject to additional human interventions. Furthermore, although regional slopes are quite gentle, there is localized high relative relief. Sacavém vegetation, in the gullied area, consists of brushwood. Secondary mixed forest and brushwood are the

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

Geochemistry and Nd-isotope systematics of chemical and terrigenous sediments from the Dun Mountain Ophiolite, New Zealand

International Nuclear Information System (INIS)

Sivell, W.J.

2002-01-01

Two sedimentary associations closely related to temporally discrete ophiolitic magma suites occur within the Early Permian Dun Mountain Ophiolite Belt (DMOB), New Zealand. These are: (1) a suite of diverse chemical sediments and turbidite argillites (TA) that bear an intimate depositional relationship to early-formed pillow lavas (back-arc basin basalts); and (2) a younger, lithic-dominated, bimodal, coarse sandstone-ophiolitic rudite assemblage of proximal turbidite/mass-flow origin, rich in clasts of infant-arc magmas which comprise the bulk of the ophiolite. There are four groups of DMOB chemical sediments. Red hematitic chert (group 1) fills interstices between basalt pillows, and black nodular Fe-Mn deposits (group 2) occur along pillow lava/sediment interfaces. These facies are overlain by red mudstones (group 3), and mottled orange-olive brown mudstones (altered hyaloclastites; group 4). Geochemical features (including REE contents, Fe/Ti and transition ratios) indicate that the cherts reflect silica and metalliferous contributions to sea water, promoted by low-temperature hydrothermal alteration of glassy basalt, while group 4 muds represent residual components in halmyrolytically altered volcanic glass. Transition metal and REE enrichments in group 2 nodules (with high Ce/Ce*, Ni/Fe, and Cu/Fe ratios) reflect hydrogenous chemisorption to a hydothermal component (with high Ba and Sr). The nodules possess ε Nd (T) values (c. 0) identical to those calculated for Permian sea water. Group 3 red muds have lower ε Nd (T) = -1 to -2, and Nd model ages (T) Nd DM) that indicate contributions from continentally derived fluvial particulate fallout of mean Proterozoic age. For the nodules and red muds, strong negative correlations between Mn/Fe, Nd, Ce*/Ce, and ε Nd (T) are attributed to increasing diagenetic influence in the muds. ε Nd (T) values (c. +2) in group 4 muds are transitional toward higher values in their (hyaloclastite) basalt glass precursors

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

International Nuclear Information System (INIS)

Tremosa, J.

2010-01-01

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 k T 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 k T ranging between 6 x 10 -12 and 2 x 10 -10 m 2 K -1 s -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

Analysis of the temperature and pore water pressure field in the TED heating experiment

International Nuclear Information System (INIS)

Garitte, B.; Vaunat, J.; Gens, A.; Conil, N.; Armand, G

2012-01-01

Document available in extended abstract form only. The TED experiment is a heating experiment in Callovo-Oxfordian Clay performed in the Meuse Haute Marne underground research laboratory. It was set up by Andra to confirm the results obtained in a previous thermal experiment (TER). The main objectives are: characterisation of the thermal properties of intact argillite, identification of the Thermo-Hydro-Mechanical (THM) coupling parameters, improvement of the understanding of THM behaviour and comparison of parameters measured in-situ and in the laboratory. The three heaters in the TED experiment were installed parallel at a distance of about 2.7 m to reproduce as closely as possible the real storage case (HA cells). This arrangement should allow the verification of: i) the superposition of several temperature fields generated by the three heaters and ii) the overpressure generated in the symmetry planes between the three heaters. Three heaters 4 m long and 0.143 m diameter have been installed in parallel boreholes drilled form GED gallery. To limit the influence of the conditions prevailing in the gallery, a distance of 12 m have been left between the GED wall and the closest extremity of the heaters. Rock has been intensively instrumented within a zone of 15 m around the heaters. There are 108 thermal sensors, 10 pore pressure sensors, 2 extensometers/inclinometers, placed in 13 different small diameter boreholes (56 mm). 11 boreholes were filled with bentonite (those containing thermal and pore pressure sensors) and 2 of them left open (those equipped with extensometer/inclinometers). First heating started on 22 January 2010 at the central heater and consists of three steps: 120 days at 180 W, 150 days at 300 W and one last period at 600 W. The two lateral heaters have been switched on after 14 months following the same heating sequence. The concept and the results of the TED experiment are fully described in a companion paper. Concerning heat transport

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)

Huclier-Markai, S.; Landesman, C.; Grambow, B.; Rogniaux, H.; Monteau, F.; Vinsot, A.

2010-01-01

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

Fluids transfer in porous media, the case of carbonates and clay/limestone interfaces. Integrated study of petrophysical, sedimentology and microstructures.The case of two carbonates: the case of two carbonates the Oolithe Blanche from the Paris Basin and the Globigerina Limestone of maltese islands

International Nuclear Information System (INIS)

Casteleyn, Lisa

2011-01-01

Geological storage is now considered as a technical solution for CO_2 storage and nuclear waste management (for high-level and intermediate-level long-lived radioactive waste). A geological storage is a long term project which implies a particular protocol in order to better determine and to better understand the host rock, especially in terms of transport mechanisms. The geological formations studied are chosen in function of their storage capacity because gas storage or nuclear waste storage do not need the same requirements. In case of CO_2 storage, the host formation must provide good reservoir properties in order to facilitate the injection. Here, the safety of the storage is guaranteed by traps (structural, residual, mineral) and by the presence of a cap rock. Concerning nuclear waste storage, the host must retain at best the potential radioactive fluids and gas leaks, and this is the reason why storage sites are studied within low porous and low permeable formation, like argillite organelles. The work presented in the PhD thesis is related to two storage projects. The first one is focused on the petrophysical study of a potential host for CO_2 storage in the Paris Basin, the 'Oolithe Blanche' carbonate formation. The second project is an analogue study of the sedimentary structure explored in the Meuse/Haute-Marne laboratory. This laboratory is studied by ANDRA to be the first nuclear waste storage in a deep geological formation in France. The analogue was found in maltese archipelagos, which presents almost the same tabular structure as the one observed in the Meuse/Haute-Marne laboratory: limestone/clay/limestone affected by a weak tectonic deformation. In the first part, the Oolithe Blanche Formation study allowed to determine the reservoir properties of the three principals facies of the formation. This study was realized on plugs sampled on quarries in Burgundy (France). Those facies are characterized by different environmental processes and deposit

The nature of hydrothermal fluids in the Kahang porphyry copper deposit (Northeast of Isfahan based on mineralography, fluid inclusion and stable isotopic data

Directory of Open Access Journals (Sweden)

Salimeh Sadat Komeili

2017-02-01

Full Text Available Introduction The Kahang Cu- Mo deposit is situated approximately 73 Km northeast of Isfahan. Asadi (2007 identified a geological reserve of 40 Mt (proven reserve grading at 0.53 Cu, 0.02 Mo and estimated reserve of 120 Mt. All the rock types in the region have been subjected to hydrothermal solutions which gave rise to three different alteration facies. The dacite and rhyodacite volcanic rocks and granitic- granodioritic stocks have experienced phyllic alteration. Disseminated and stockwork siliceous veins are the major styles of mineralization in this zone. Intermediate argillitic alteration developed on a part of dacitic and rhyodacitic rocks whereas andesite and basaltic-andesite plus related pyroclastic rocks have been subjected to propyllitic alteration. This paper presents the results of geological and mineralogical studies carried out in the Kahang area. This preliminary information is integrated with additional data on ore mineralogy, fluid inclusions and stable isotopes in view of understanding the genesis of the Cu- Mo deposit and the nature of the fluids involved in ore formation. Materials and Methods A total of 18 polished thin sections were prepared at the University of Isfahan for optical study. Fluid inclusions study was carried out on 8 double polished quartz thin sections (stockworks containing ore mineralization from phyllic zone. H – O stable isotope analysis was performed on 4 quartz samples from siliceous stockworks (from phyllic altered zone and one vein epidote sample (from propyllitic zone. All isotopic analyses were performed at the University of Oregan, Oregan, USA. Discussion In the investigated mineralization area, the hypogene zone is characterized by the presence of pyrite, chalcopyrite, bornite and magnetite. Hematite, goethite, jarosite, malachite and azurite are the predominant minerals of supergene zone. The major textures of the primary sulfides are disseminated, vein and veinlet. Pyrite is the most common

Thermodynamic of hydration of a Wyoming montmorillonite saturated with Ca, Mg, Na and K

International Nuclear Information System (INIS)

Vieillard, P.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Giffaut, E.

2010-01-01

Document available in extended abstract form only. In the context of a disposal within clayey formations (Callovo-Oxfordian argillite) or using clayey barriers, the assessment of the long-term behavior of clay materials by geochemical modeling, requires thermodynamic properties of clay minerals. The Thermochimie database has been created by ANDRA in 1996 in order to provide coherent thermodynamic data of many minerals of interests with regards to this context, such as clay minerals. However, the thermodynamic properties of clay minerals, which govern the stability of these minerals in solution are still poorly understood. Indeed, there is little experimental data available in the literature concerning the hydration of smectites. On the other hand, it is not possible to acquire all the experimental thermodynamic hydration properties of clay minerals involved in natural systems or likely to be in the implementation of a deep disposal. In this study, we propose a method to estimate the thermodynamic hydration properties of a clay mineral. By considering the following reaction: Smectite nm H 2 O Smectite (0 H 2 O) + nm H 2 O (l), the hydration of smectite is calculated from an equilibrium condition involving anhydrous and hydrous components in which nm is the maximal number of moles of water in the fully hydrated end-member. By using a solid-solution formalism, the variation of the hydration state of a smectite with temperature or [H 2 O] can be possible. Analysis of experimental data indicates that solid solutions of hydrous and anhydrous smectite components at 25 deg. C and 1 bar are not ideal but can be expressed in terms of regular solution theory by considering the excess molal enthalpy of mixing (Hxs), the excess molal entropy of mixing (Sxs) and excess molal Gibbs free energy of mixing (Gxs) for binary solid solutions of homologous hydrous and anhydrous smectite components expressed in terms of Margules parameters W1 and W2. A compilation of measurements of

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

Quantitative Analysis of Piezoelectric and Seismoelectric Anomalies in Subsurface Geophysics

Science.gov (United States)

Eppelbaum, Lev

2017-04-01

seismoelectric interpretation results with other geophysical methods, some schemes developed in theory of information (Eppelbaum, 2014) and wavelet theory (Eppelbaum et al., 2011) can be effectively applied. Table 1. Classification of some rocks, ores, and minerals by their piezoactivity d (10-14 Coulomb/Newton) (after Neishdadt et al., 2006 and Neishtadt and Eppelbaum, 2012, with modifications) Piezoactivity groupRock, Ore, Mineral dmin - dmaxdaver Quartz-tourmaline-cassiterite ore 0.8-28 15.7 Antimonite-quartz ore 0.2-1.35 0.6 I Apatite-nepheline ore 0-5 0.9 Galenite-sphalerite ore 0.2-7.7 3.3 Ijolite 0.1-8 1.2 Melteigite 0.2-5 1.6 Pegmatite 0.1-4.8 1.3 Skarn with galenite-sphalerite mineralization0.1-3 0.6 II Sphalerite-galenite ore 0.3-7.7 3.8 Turjaite 0.9-4.8 2.2 Urtite 0.1-32.5 3.4 Juvite 0.2-5.4 1.8 Aleurolite silicificated 0-0.5 0.2 Aplite 0-1.7 0.6 Breccia aleurolite-quartz 0.1-0.4 0.2 Gneiss 0-1.4 0.2 Granite 0-1.6 0.4 Granodiorite 0-0.2 0.1 Quartzite 0-3.3 0.6 III Pegmatite ceramic 0-1 0.15 Sandstone silicificated and tourmalinised 0.1-1.4 0.5 Feldspars 0-0.4 0.15 Porphyrite 0-0.3 0.1 Ristschorrite 0.3-0.9 0.5 Schist argillaceous 0-0.6 0.2 Hornfels 0-0.4 0.2 Skarn sphaleritic-garnet 0-1 0.3 Skarn pyroxene-garnet 0-0.2 0.1 Aleurolite, amphibolites, andesite, gabbro, 0-0.1 0.05 IV greisens, diabase, sandstone Argillite, beresite, dacite, diorite-porphyrite, 0 0 felsite-liparite, limestone, tuff, fenite I - highly active — piezo-activity of samples is greater than 5.0 ṡ 10-14 C/N II - moderately active — piezo-activity of samples is (0.5 - 5.0) ṡ 10-14 C/N III - weakly active — piezo-activity of samples is lower than 0.5 ṡ 10-14 C/N IV - non-active — piezo-activity of samples are near zero. REFERENCES Alperovich, L.S., Neishtadt, N.M., Berkovitch, A.L. and Eppelbaum, L.V., 1997. Tomography approach and interpretation of the piezoelectric data. Trans. of IX General Assembly of the European Geophysical Society. Strasbourg, France, 59/4P02, p. 546. Boulytchov