Characterisation of Granite Fractures From the In-Situ FEBEX Experiment (Grimsel, Switzerland): ossible Effects on Bentonite Colloid and Radionuclide Transport

2009 ◽  
Vol 1193 ◽  
Author(s):  
Ursula Alonso ◽  
Tiziana Missana ◽  
Miguel Garcia-Gutierrez ◽  
Alessandro Patelli ◽  
Nairoby Albarran ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Test Site ◽  
Swiss Alps ◽  
Radionuclide Transport ◽  
In Situ Experiment ◽  
Bentonite Colloid ◽  
High Level ◽  
Micrometer Scale ◽  
Colloid Formation

AbstractThe FEBEX in-situ experiment, installed in 1997 at the Grimsel Test Site (GTS, Switzerland) 400 m depth under the Swiss Alps, simulates a high level radioactive waste repository (HLWR) emplaced in granite. Its initial aim was to study the performance of a bentonite engineered barrier but recently, two new boreholes were drilled in the granite to study the possible bentonite colloid formation and their migration in the granite.This study presents the characterization performed, at the micrometer scale, of the threemain water conductive fractures that were identified on the granite cores extracted from the newboreholes. These fractures are possible pathways for bentonite colloid transport (or retention),may be source of natural colloids and may condition colloid stability. The nuclear ion beamtechniques µ-Particle X-Ray Emission (µPIXE) and Rutherford Backscattering Spectrometry(RBS) were applied for visualizing and quantifying the elemental composition of the fracturessurface and of the surrounding micro-fractures, as support of the bentonite colloid analyses.

Building Confidence in Radionuclide Transport Models for Fractured Rock: The Nagra/JNC Radionuclide Retardation Programme

2000 ◽  
Vol 663 ◽  
Author(s):  
K. Ota ◽  
W.R. Alexander ◽  
P.A. Smith ◽  
A. Möri ◽  
B. Frieg ◽  
...  
Keyword(s):  
Fractured Rock ◽  
Test Site ◽  
Process Models ◽  
Swiss Alps ◽  
Radionuclide Transport ◽  
Transport Models ◽  
North East ◽  
Host Rocks ◽  
Experimental Technology

ABSTRACTThe joint Nagra/JNC Radionuclide Retardation Programme has now been ongoing for 15 years with the main aim of direct testing of radionuclide transport models in as realistic a manner as possible. A large programme of field, laboratory and natural analogue studies has been carried out at the Grimsel Test Site in the central Swiss Alps and the Kamaishi In Situ Test Site in north-east Japan. The understanding and modelling of both the processes and the structures influencing radionuclide transport/retardation in fractured host rocks have matured as has the experimental technology, which has contributed to develop confidence in the applicability of the underlying research models in a repository performance assessment. In this paper, the successes and set-backs of this programme are discussed as is the general approach to the thorough testing of the process models and of model assumptions. In addition, a set of key findings is presented, involving discussions on the enhancement of confidence through the program.

Studies on radionuclide transport behaviour–The next generation of in-situ experiments at the Grimsel Test Site

2009 ◽  
Vol 1193 ◽  
Author(s):  
Andrew James Martin ◽  
Ingo Blechschmidt
Keyword(s):  
Shear Zone ◽  
Diffusion Processes ◽  
Test Site ◽  
Core Material ◽  
Laboratory Studies ◽  
Grimsel Test Site ◽  
And Migration ◽  
Colloid Formation

AbstractTwo recent ongoing major projects at the Grimsel Test Site (GTS) (www.grimsel.com) that were initiated to simulate the long-term behaviour of radionuclides in the repository near-field and the surrounding host rock are presented: the Colloid Formation and Migration (CFM) project, which focuses on colloid generation and migration from a bentonite source doped with radionuclides and the Long-Term Diffusion (LTD) project, which aims at in-situ verification and understanding of the processes that control the long-term diffusion of repository-relevant radionuclides. So far, the CFM project has principally involved: development and implementation of a state-of-the-art sealing concept to control hydraulic gradients in a shear zone to imitate repository-relevant conditions; extensive laboratory studies to examine bentonite erosion and colloid formation in a shear zone; and, development of models to estimate colloid formation and migration. The next stage will be to assess the behavior of bentonite colloids generated from a radionuclide spiked bentonite source-term emplaced into the controlled flow field of the shear zone. This will be coupled with further extensive laboratory studies in order to refine and evaluate the colloid models currently used in performance assessments. The LTD project consists of: a monopole diffusion experiment where weakly sorbing and non-sorbing radionuclides (3H, 22Na, 131I, 134Cs) have been circulating and diffusing into undisturbed rock matrix since June 2007; experiments to characterise pore space geometry, including determination of in-situ porosity with 14C doped MMA resin for comparison with laboratory derived data; a study of natural tracers to elucidate evidence of long-term diffusion processes; and, an investigation of the in-situ matrix diffusion paths in core material from earlier GTS experiments. Future experiments will focus on diffusion processes starting from a water-conducting feature under realistic boundary conditions.

Grimsel Test Site - Phase VI: Review of Accomplishments and Next Generation of In-Situ Experiments Under Repository Relevant Boundary Conditions

2008 ◽  
Vol 1107 ◽  
Author(s):  
Ingo Blechschmidt ◽  
Stratis Vomvoris ◽  
Joerg Rueedi ◽  
Andrew James Martin
Keyword(s):  
Near Field ◽  
Planning Horizon ◽  
Test Site ◽  
Low Ph ◽  
Swiss Alps ◽  
In Situ Experiments ◽  
Grimsel Test Site ◽  
And Migration

AbstractThe Grimsel Test Site owned and operated by Nagra is located in the Swiss Alps (www.grimsel.com). The Sixth Phase of investigations was started in 2003 with a ten-year planning horizon. With the investigations and projects of Phase VI the focus has shifted more towards projects assessing perturbation effects of repository implementation and projects evaluating and demonstrating engineering and operational aspects of the repository system. More than 17 international partners participate in the various projects, which form the basic organisational “elements” of Phase VI. Scientific and engineering interaction among the different projects is ensured via an annual meeting and several experimental team meetings throughout the year. On-going projects include: evaluation of full-scale engineered systems under simulated heat production and long-term natural saturation (NF-Pro/FEBEX), gas migration through engineered barrier systems (GMT, finished this year), emplacement of a shotcrete low-pH plug (ESDRED/Module IV), testing and evaluation of standard monitoring techniques (TEM).Numerous in-situ experiments with inactive tracers and radionuclides were successfully carried out over the past few years at the Grimsel Test Site (GTS). For the GTS Phase VI, three major projects have been initiated to simulate the long-term behaviour of contamination plumes in the repository near-field and the surrounding host rock:•The CFM (Colloid Formation and Migration) project, which focuses on colloid generation and migration from a bentonite source doped with radionuclides•The LCS (Long-Term Cement Studies) project, which aims at improving the understanding of low-pH cement interaction effects in water conducting features•The LTD (Long-Term Diffusion) project, which aims at in-situ verification of long-term diffusion concepts for radionuclidesAs Phase VI approaches its mid-term point, what are the next steps planned? The accomplishments assessed to date and the opportunities with the on-going projects as well as new projects – currently under discussion – are presented herein

In-Situ Testing of Nuclear Waste Glasses in a Clay Laboratory - Results After Two Years Corrosion

1989 ◽  
Vol 176 ◽  
Author(s):  
P. Van Iseghem ◽  
W. Timmermans ◽  
B. Neerdael
Keyword(s):  
Analytical Data ◽  
Waste Form ◽  
Laboratory Simulation ◽  
High Level Waste ◽  
In Situ Experiment ◽  
Boom Clay ◽  
Major Mechanism ◽  
Mechanism Of Interaction ◽  
High Level

ABSTRACTThe first retrieval of an in-situ experiment on the interaction waste form - clay host in the underground laboratory under the Mol site has been finished successfully. The test consisted in a two years exposure of various candidate simulated waste glasses at 90°C to Boom clay. The retrieval was done by overcoring. The experimental data showed satisfactorily correspondence between in-situ and laboratory simulation tests both for mass loss and surface analytical data, supporting the validity of the in-situ test as it was performed. The thickness of waste form dissolved within two years varies between 40 and 325 μm (case of the high-level waste glasses), depending on the composition. Matrix dissolution is expected to be the major mechanism of interaction.

Hyperalkaline Cement Leachate-Rock Interaction and Radionuclide Transport in a Fractured Host Rock (HPF Project)

2003 ◽  
Vol 807 ◽  
Author(s):  
Urs Mäder ◽  
Bernd Frieg ◽  
Ignasi Puigdomenech ◽  
Michel Decombarieu ◽  
Mikazu Yui
Keyword(s):  
Shear Zone ◽  
Reactive Transport ◽  
Measurement Techniques ◽  
Test Site ◽  
Transport Modeling ◽  
Reactive Transport Modeling ◽  
Radionuclide Transport ◽  
Tracer Transport ◽  
Rock Interaction

ABSTRACTThe HPF project (Hyperalkaline Plume in Fractured rock) at the Grimsel Test Site comprises an underground long-term field experiment in a shear zone, in-situ radionuclide transport experiments, two laboratory core infiltration experiments, sophisticated reactive transport modeling exercises, studies on radionuclide stability and solubility, innovative on-line measurement techniques and development of equipment for high-pH conditions (K-Na-Ca-OH, pH = 13.4 at 15 °C). Results to date indicate a decrease in the overall transmissivity of the tested shear zone over a duration of 2 years accompanied by channeling of flow as evidenced by repeat dipole tracer testing with Na-fluorescein, 82Br, 131I, 24Na, and 85Sr. The associated evolution in fluid chemistry indicates the in situ formation of Ca-Si-hydrates. Tracer transport modeling of dipole tests are based either on a heterogeneous porous medium approach or on discrete fracture models. Reactive transport modeling is achieving reasonable agreement with a laboratory core infiltration experiment. Integral to the project are supporting sorption / stability studies, colloid measurements, and development of analytical and measurement techniques.

The Assessment of Radionuclide Retardation in Fractured Crystalline Rocks

1997 ◽  
Vol 506 ◽  
Author(s):  
W. Russell Alexander ◽  
Kunio Ota ◽  
Bernhard Frieg ◽  
Ian G. Mckinley
Keyword(s):  
Test Site ◽  
Breakthrough Curves ◽  
Swiss Alps ◽  
Radionuclide Migration ◽  
Sorption Data ◽  
Kd Values ◽  
Long Term Experiment ◽  
Fractured Crystalline Rocks ◽  
Tracer Migration

ABSTRACTThe joint Nagra/PNC Radionuclide Migration Programme has been running for over ten years in Nagra‘s Grimsel Test Site in the central Swiss Alps. The programme is specifically aimed at the further development of conceptual models of radionuclide transport in the geosphere, rigorously testing the applicability of current transport codes to quantify radionuclide migration in situ and assessing how successfully laboratory sorption data (specifically, Kd values) may be extrapolated to in situ conditions to predict radionuclide retardation in the geosphere [1]. A large series of field tracer migration experiments was carried out in a hydrologically well characterised water-bearing, complex fracture (or shear zone), increasing in complexity from simple, nonsorbing fluoresceine (a fluorescent dye), 3H, 3,4He, 82Br and 123I through weakly sorbing 22.24Na,85Sr and 86Rb to a final, long-term experiment with moderately sorbing 134,137Cs. The radionuclides were injected into a dipole flow field where the flowpath length, dipole width or shape and groundwater flow velocity were all varied. After a considerable learning period, generally good fits could be obtained between transport code predictions and subsequent field tracer breakthrough curves, suggesting that the transport codes tested were a reasonable representation of in situ conditions.

Colloid and Radionuclide Transport in Granite Under Low Water Flow Rates Expected in a Geological Repository

2009 ◽  
Vol 1193 ◽  
Author(s):  
Nairoby Albarran ◽  
Tiziana Missana ◽  
Ursula Alonso ◽  
Miguel Garcia-Gutierrez ◽  
Manuel Mingarro ◽  
...  
Keyword(s):  
Water Flow ◽  
Fractured Rock ◽  
Water Flow Rate ◽  
Test Site ◽  
Crystalline Rock ◽  
Low Flow ◽  
Radionuclide Transport ◽  
Hydrodynamic Conditions ◽  
Flow Rates ◽  
High Level

AbstractColloids generated from the engineered barriers of a high level radioactive waste repository (HLWR) emplaced in crystalline rock could play a significant role in radionuclide transport and they are of concern for the safety assessment of these repositories.The main objectives of this study are: a) to analyze the transport properties of colloids in a crystalline fractured rock under hydrodynamic conditions as similar as possible to those expected in a repository (i.e. low flow rates) and b) to discuss the effects of their presence on the transport of radionuclides.Transport experiments with bentonite and latex colloids in a fractured granite column from the Grimsel Test Site (Switzerland) were carried out, under geochemical conditions ensuring colloid stability (alkaline and low ionic strength water). Transport experiments were also carried out with 85Sr and 233U and the results with and without the presence of bentonite colloids were compared.Colloid filtration in the fracture was always observed, even when colloids presented high stability and the conditions were unfavorable to colloid attachment to rock surfaces, being both the colloids and the rock negatively charged and the fracture surface smooth. The retention in the fracture depended on the water flow rate, increasing the retention as the water flow decreased.This work illustrates as both the mobile and retained fraction of colloids, which strongly depend on the hydrodynamic conditions, are of importance in the overall radionuclide mobility.

scholarly journals Insights to Repository Performance through Study of a Nuclear Test Site

2000 ◽  
Vol 663 ◽  
Author(s):  
D.K. Smith ◽  
A.B. Kersting ◽  
J.L. Thompson ◽  
D.L. Finnegan
Keyword(s):  
Tectonic Setting ◽  
Test Site ◽  
Yucca Mountain ◽  
Nuclear Test ◽  
High Level Waste ◽  
Radionuclide Transport ◽  
Source Terms ◽  
Nevada Test Site ◽  
Waste Repository ◽  
High Level

ABSTRACTUnderground nuclear test sites offer an unprecedented opportunity to evaluate processes relevant to high-level waste repository performance in the absence of engineered barriers. Radionuclide migration programs at the Nevada Test Site represent a twenty-five year systematic investigation of the diverse radiologic source terms residual from weapons testing and the evolution of the hydrologic source term which comprises those radionuclides dissolved in or otherwise available for transport by groundwater. The Nevada Test Site shares actinide source terms, correlative geology, an identical tectonic setting, similar climate, and a thick unsaturated zone with the adjacent potential Yucca Mountain high-level waste repository and provides a natural laboratory to assess long-term radionuclide transport in the near field. Analog studies may ultimately help validate predictions of radionuclide transport from the potential Yucca Mountain repository.

Grimsel Test Site — Phase VI: Review of Accomplishments and Next Steps

2007 ◽  
Author(s):  
Stratis Vomvoris ◽  
Wolfgang Kickmaier
Keyword(s):  
Ad Hoc ◽  
Field Testing ◽  
Planning Horizon ◽  
Test Site ◽  
Swiss Alps ◽  
Tracer Transport ◽  
Geophysical Investigation ◽  
Grimsel Test Site

The Grimsel Test Site owned and operated by Nagra is located in the Swiss Alps (www.grimsel.com). The sixth Phase of investigations was started in 2003 with a ten-year planning horizon. With the investigations and projects of Phase VI the focus is shifted more towards projects assessing perturbation effects of repository implementation and projects evaluating and demonstrating engineering and operational aspects of the repository system. More than 17 international partners participate in the various projects, which form the basic organisational ‘elements’ of Phase VI, each one further structured in field-testing, laboratory studies, design and modelling tasks, as appropriate. Each project phase is planned with a duration of 3 to 5 years, to facilitate all practical and administrative aspects, ensuring flexibility for updating the overall plan with the recent findings. Scientific and engineering interaction among the different projects is ensured via the annual international meeting and ad-hoc meetings, as appropriate. As Phase VI approaches its mid-term point, a review of the accomplishments to date is performed to provide a sound basis for the detailed planning of the next steps. The accomplishments to date are described and assessed below; the opportunities with the on-going projects as well as new projects – currently under discussion – are also presented and discussed. The on-going projects include: studies of the long-term diffusion with emphasis on the processes in the rock matrix (LTD); colloid studies under in-situ generation conditions and migration velocities closer to velocities expected in an actual repository site (CFM); studies of the long-term cement interactions with natural systems (LCS); evaluation of full-scale engineered systems under simulated heat production and long-term natural saturation (NF-Pro/FEBEX); gas migration through engineered barrier systems (GMT); emplacement of shotcrete low-pH plug (ESDRED/Module IV); test and evaluation of monitoring systems (TEM). In addition, various shorter term projects assessing, for example, new geophysical investigation tools, wireless transmission, testing new tools and training for in-situ tracer transport studies have been performed and/or are planned for the near future.

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