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AbstractAbstract
[en] For the Operating Phase of the SKB Aespoe Hard Rock Laboratory (HRL), the Swedish Nuclear Fuel and Waste Management Company (SKB) initiated the Tracer Retention Understanding Experiments (TRUE) with the objective to improve the understanding of radionuclide transport and retention processes in fractured crystalline rock. Overall objectives included enhancement of confidence in models for transport of sorbing radionuclides in performance assessment (PA), and to show that pertinent transport data can be obtained from site characterisation or field experiments, and that laboratory results can be related to retention parameters obtained in situ. A basic drive from PA has been to obtain in situ data on transport and retention of sorbing radionuclides at different length scales. In addition, addressing the multiple scales embedded in TRUE is relevant to taking the step from experimental scales to site scale (100-1000 m). The TRUE experiments performed at Aespoe have successfully demonstrated the possibility to run well-controlled quantitative experiments with radioactive sorbing tracers in interpreted single structures and networks of deterministic fractures/structures over length scales < 100 m. Prerequisites for design, performance and associated model prediction and evaluation of such tests are robust hydro-structural models of the studied networks of structures. Of special importance in building such models in fractured crystalline rock are observations of connectivity as obtained from pressure responses together with borehole TV images and detailed flow log data. Tracer dilution tests have been identified as crucial for identification of candidate source sections for tracer tests in the borehole arrays, and also as a means to verify hydro-structural models. Numerical modelling of the TRUE experiments have been performed with a wide range of approaches/concepts ranging from analytical models, through stochastic continuum, discrete fracture network and channel network models, to more performance assessment type model approaches. The results indicate successful outcome of model predictions in relation to experimental data on a length scale < 15 m. The evaluation of the TRUE Block Scale experiments is expected to help increase predictive capability on a 100-m length scale. Unlimited diffusion/sorption is regarded as the most important retention process for the TRUE experimental time scales. However, in the case of the TRUE-1 experiments, no unambiguous proofs exist as to whether the accessible pore space is provided by the rock matrix (altered rim zone including fault breccia pieces/fragments) or possible fine-grained fault gouge. Impregnation of TRUE Block Scale wall rock and fault breccia pieces/fragment samples with 14C-PMMA have helped reveal characteristics and distributions of porosity of important constituents of the studied transport paths. (author)
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Organisation for Economic Co-Operation and Development - Nuclear Energy Agency, 75 - Paris (France); 269 p; ISBN 92-64-19695-1; ; 2002; p. 119-127; Workshop proceedings Radionuclide retention in geologic media; Oskarshamn (Sweden); 7-9 May 2001; 20 refs.
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AbstractAbstract
[en] A comprehensive series of tracer tests on a relatively large scale have been performed by SKB at Finnsjon, Sweden, to increase understanding of transport phenomena which govern migration of radionuclides in major fracture zones. A preliminary tracer test during hydraulic interference tests and a radially converging test and a dipole test have been performed with both sorbing and slightly sorbing tracers. Work on the Finnsjon test case during Phase 1 of the INTRAVAL international project involved 10 models ranging from advection-dispersion approaches to more complex fracture network approaches. The main conclusion of this phase is that tracer test data from one or two tests at a given site are not sufficient to discriminate between models and active processes. The phase 2 studies, which involved 9 project teams from 7 countries, are dominated by porous media approaches in two dimensions. The general conclusion is that flow and transport in the studied fracture zone is governed by advection and that hydrodynamic dispersion is needed to explain the breakthrough curves. A variety of validation aspects have been considered. (J.S.). 7 refs., 3 figs., 5 tabs
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Nuclear Energy Agency, 75 - Paris (France); 510 p; ISBN 92-64-14467-6; ; 1995; p. 87-99; Organisation for Economic Co-Operation and Development; Paris (France); GEOVAL'94 Symposium; Paris (France); 11-14 Oct 1994
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Book
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Conference
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BOREHOLES, COMPUTERIZED SIMULATION, COORDINATED RESEARCH PROGRAMS, DIFFUSION, ELECTRIC CONDUCTIVITY, FINITE ELEMENT METHOD, GAUSSIAN PROCESSES, GEOLOGIC FRACTURES, GEOLOGIC MODELS, GEOLOGIC STRUCTURES, GRANITES, HYDRAULIC CONDUCTIVITY, HYDRAULICS, ISOTOPE DILUTION, POROUS MATERIALS, RADIOACTIVE WASTE DISPOSAL, RADIONUCLIDE MIGRATION, SITE CHARACTERIZATION, SORPTIVE PROPERTIES, STOCHASTIC PROCESSES, TRACER TECHNIQUES, WATER INFLUX
CALCULATION METHODS, CAVITIES, ELECTRICAL PROPERTIES, ENVIRONMENTAL TRANSPORT, IGNEOUS ROCKS, ISOTOPE APPLICATIONS, MANAGEMENT, MASS TRANSFER, MATERIALS, NUMERICAL SOLUTION, PHYSICAL PROPERTIES, PLUTONIC ROCKS, RESEARCH PROGRAMS, ROCKS, SIMULATION, SURFACE PROPERTIES, WASTE DISPOSAL, WASTE MANAGEMENT
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Winberg, A.
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)1991
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)1991
AbstractAbstract
[en] A discussion was presented of the role and relative importance of the disturbed rock zone (DRZ) around the underground openings of a repository for nuclear waste in crystalline rock. The term disturbed rock zone was defined and possible criteria to be sued to distinguish if from undisturbed rock was suggested. The processes decisive for the hydraulic characteristics of the DRZ were discussed. With regard to the integral hydraulic characteristics of the DRZ, the effects of the excavation methodology, stress redistribution, thermal changes, chemical changes and backfill were discussed. A review of in-situ observations of the DRZ was provided. Model analysis where the DRZ has been explicitly or implicitly represented, either from a phenomenological and performance assessment aspect were reviewed. The implications of the disturbed rock zone for the safe performance of a nuclear waste repository were discussed. Conceptual models for the geometry of the DRZ and hydraulic conductivity distribution in the DRZ were suggested. (au) (82 refs.)
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Jun 1991; 77 p
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Report
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Numerical Data
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Winberg, A.
Swedish Nuclear Fuel and Waste Management Co, Stockholm (Sweden)1991
Swedish Nuclear Fuel and Waste Management Co, Stockholm (Sweden)1991
AbstractAbstract
[en] Hydraulic conductivity data from the Stripa mine were analysed to establish the characteristics of spatial variability. In addition the univariate statistics were calculated. Data on different supports were analysed; 10 m data, variable section length (1-7 m), and the latter variable section data deregularised to 1 m data. The analyses of data from boreholes with orthogonal orientations indicated an apparent anisotropy in the geometric mean hydraulic conductivity, with a one to two order higher mean conductivity in the east-west direction than that on north-south. The analysis of spatial variability on a 10 m support revealed weak spatial correlation, whereas that based on the data deregularised to 1 m data showed finite, well developed spatial correlation with practical ranges of c. 10 m. The covariance structure of hydraulic conductivity, as opposed to that of the calculated geometric mean hydraulic conductivities, showed an isotropic structure. The established variograms constitute a starting point for further data expansion and estimation by eg. stochastic continuum simulations of groundwater flow and mass transport within the SCV block at Stripa. (au)
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Nov 1991; 78 p
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Report
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Numerical Data
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Olsson, O.; Winberg, A.
Field tracer experiments. Role in the prediction of radionuclide migration1997
Field tracer experiments. Role in the prediction of radionuclide migration1997
AbstractAbstract
[en] SKB's concept on deep geological disposal of spent nuclear fuel is based on a multi-barrier system for isolation of the spent fuel from the biosphere. The barriers are a low-solubility waste form, encapsulation of the fuel in a copper canister, a bentonite buffer surrounding the canister, and the host rock. In case of an initial canister damage, the retention capacity of the host rock for the short lived radionuclides such as Cs and Sr is important. For the Operating Phase of the Aespoe Hard Rock Laboratory the need for a better understanding of radionuclide transport and retention processes was recognized. This included enhancement of confidence in models to be used for quantifying transport of sorbing radionuclides in performance assessment. Further, to be able to show that pertinent transport data could be obtained from site characterization or field experiments and that laboratory results could be related to retention parameters obtained in situ. To resolve these issues SKB initiated the Tracer Retention Understanding Experiments (TRUE). (author)
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Nuclear Energy Agency (ed.); 258 p; ISBN 92-64-16013-2; ; 1997; p. 145-155; Field tracer experiments. Role in the prediction of radionuclide migration; Cologne (Germany); 28-30 Aug 1996; 2 refs.
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Book
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Winberg, A.
First TRUE Stage - Transport of solutes in an interpreted single fracture. Proceedings from the 4th international seminar2001
First TRUE Stage - Transport of solutes in an interpreted single fracture. Proceedings from the 4th international seminar2001
AbstractAbstract
[en] One component in the Tracer Retention Understanding Experiments at the SKB Aespoe Hard Rock Laboratory is the TRUE Block Scale experiment which focuses on the 10 - 100 m length scale. The objectives of TRUE Block Scale were to increase understanding and capability to predict transport and retention fracture networks. An iterative approach was adopted which included drilling, characterisation of five exploration bore-holes. The results indicate that it is possible to build relatively robust hydrostructural models of a rock volume on a 300 m length scale, using a few and relatively unsophisticated characterisation techniques (registration of pressure responses, borehole TV (BIPS) and high resolution flow logging). It was found that the basic hydrostructural entities of the investigated rock block were identified using data from the first three boreholes. Tracer dilution tests proved to be an effective means to identify suitable tracer injection sections for any given sink. Subsequent experiments have successfully demonstrated the possibility to run well-controlled, quantitative experiments with radioactive sorbing tracers in interpreted single structures and networks of deterministic fractures/structures over length scales < 100 m. A Perquisite for design, performance and associated model prediction and evaluation of the performed tests was a robust hydro-structural model. The breakthrough curves from performed tracer indicate that the longer and more complex source-sink setups show more profound indications of matrix diffusion, with near -3/2 slopes in log-log plots. It is also noted, as in the case of TRUE-1, that diffusion effects are augmented for the more sorbing tracers. Numerical modelling of the TRUE Block Scale experiments was performed with a wide range of approaches/concepts. The results indicate successful outcome of model predictions in relation to experimental data on a length scale < 15 m. The correspondence between the predicted and the in situ results are not as good for the two longer flow paths, 35 and 100 m, respectively
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Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); 219 p; ISSN 1404-0344; ; Aug 2001; p. 165-178; First TRUE stage - Transport of solutes in an interpreted single fracture. 4. international seminar; Aespoe, Oskarshamn (Sweden); 9-11 Sep 2000; Also available from: http://www.skb.se/uploads/pdf/TR-01-24webb.pdf; 16 refs, 9 figs, 1 tab
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AbstractAbstract
No abstract available
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ANDRA, 92 - Chatenay-Malabry (France); Nancy-1 Univ., 54 (France); Institut National Polytechnique, 54 - Nancy (France); Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France); 258 p; Dec 1999; p. 33; Scientific days, ANDRA 1999; Journees scientifiques, ANDRA 1999; Nancy (France); 7-9 Dec 1999
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Miscellaneous
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Carlsson, L.; Winberg, A.; Grundfeldt, B.
Swedish Nuclear Fuel Supply Co., Stockholm. Div. KBS1983
Swedish Nuclear Fuel Supply Co., Stockholm. Div. KBS1983
AbstractAbstract
[en] Hydraulic properties and conditions were investigated for the study sites of Fjaellveden, Gideaa, Kamlunge and Svartboberget. Based on geological and tectonical conditions within the sites, the bedrock was divided into different hydraulic units. Within each unit relations between hydraulic conductivity and depth were determined from hydraulic tests performed in 147 to 288 sections in 7 to 16 core-drilled boreholes in each site. The groundwater table was constructed from topographic maps and registration of groundwater head in 23 to 64 boreholes at each site. Based on the conceptual models of hydraulic units, hydraulic conductivity versus depth and groundwater tables, the groundwater flow conditions were calculated using numerical models. The models used were based on a finite element method in three-dimensions. The three study sites Fjaellveden, Gideaa and Kamlunge were modelled together with the Finnsjoen site. Each site was modelled down to a depth of 1500 m. The results given as groundwater potentials were used to calculate groundwater flow at levels of a potential repository and to estimate trajectories and travel times for groundwater from the repository level. Calculation of the groundwater recharge and head distribution along profiles conciding with boreholes made it possible to compare calculated results with measurements of the sites. (author)
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May 1983; 210 p
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AbstractAbstract
[en] Hydraulic properties of crystalline rock from four potential repository sites in Sweden were analyzed. The hydraulic conductivity of the bedrock was established by means of transient water-injection tests with constant head conducted in 25 m sections. The bedrock at the sites was divided into different hydraulic units. An effective hydraulic conductivity was calculated for the rock mass at each site. This was done on the basis of the frequency distribution of all measured values within this unit. A log-normal distribution was found to fit the data reasonably well. Regression analysis of hydraulic conductivity as a function of depth indicated similar relationships between the four sites. At a depth of 500 m the effective hydraulic conductivity for three-dimensional flow was about 5.10-11 m/s. The fracture frequency of the sites was established from existing core-logs. At depths of about 500 m the mean fracture frequency of the rock mass at the four sites was 1.8-2.5 fractures per meter. Of this total fracture frequency only a certain proportion is considered to be hydraulically conductive. This proportion was established from results of hydraulic tests performed in 2 or 3 m sections. Results obtained indicated a frequency of hydraulically conductive fractures of 0.1-0.3 fractures per meter in the rock mass at depths below 300 m. 18 references, 10 figures, 1 table
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McVay, G.L. (ed.); p. 255-267; 1984; p. 255-267; Elsevier Science Publishing Company, Inc; New York, NY (USA); Materials Research Society annual meeting; Boston, MA (USA); 14-17 Nov 1983
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Book
Literature Type
Conference; Numerical Data
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Andersson, Peter; Winberg, A.
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)1994
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)1994
AbstractAbstract
[en] A comprehensive series of tracer tests on a relatively large scale have been performed by SKB at Finnsjoen, Sweden, to increase understanding of transport phenomena which govern migration of radionuclides in major fracture zones. The conducted experiments were subsequently selected as a test in the international INTRAVAL Project, in part because the tests at Finnsjoe invite to direct address of validation of geosphere models. This report summarizes the study of the Finnsjoe test case within INTRAVAL Phase 2, which has involved nine project teams from seven countries. Porous media approaches in two dimensions dominated, although some project teams utilized one-dimensional transport models, and even three-dimensional approaches on a larger scale. The dimensionality employed did not appear to be decisive for the ability to reproduce the observed field responses. It was also demonstrated that stochastic approaches can be used in a validation process. Only four out of nine project teams studied more than one process. The general conclusion drawn is that flow and transport in the studied zone is governed by advection and that hydrodynamic dispersion is needed to explain the breakthrough curves. Matrix diffusion is assumed to have small or negligible effect. The performed analysis is dominated by numerical approaches applied on scales on the order of a 1000m. Taking scale alone into account, the results of most teams are possible to compare. A variety of validation aspects have been considered. Five teams utilized a model calibrated on one test, to predict another, whereas the two teams utilizing stochastic continuum approaches addressed; 1) validity of extrapolation of a model calibrated on one transport scale to a larger scale, 2) performance assessment implications of choice of underlying distribution model for hydraulic conductivity, respectively. 37 refs
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Jan 1994; 79 p; ISSN 0284-3757;
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