Development of a Conceptual Flow-Path Model of Nuclide Migration in Crystalline Rock - A Case Study at the Kamaishi in-Situ Test Site, Japan -

1994 ◽  
Vol 353 ◽  
Author(s):  
H. Osawa ◽  
H. Sasamoto ◽  
T. Nohara ◽  
K. Ota ◽  
H. Yoshida
Keyword(s):  
Laboratory Experiments ◽  
Test Site ◽  
Crystalline Rock ◽  
Flow Path ◽  
Path Model ◽  
Type B ◽  
Flow Paths ◽  
In Situ Test ◽  
Altered Zone

AbstractThe objective of this study is to develop a conceptual flow-path model for nuclide migration in fractured crystalline rock at the Kamaishi In-Situ Test Site because improvement of existing models of matrix diffusion |e.g. 1,2|, based on realistic geological data, is necessary for a better understanding of nuclide migration into rock matrix. Data from field observations indicate that fractures at the Kamaishi In-Situ Test Site can be classified into three types; type A with a zone of fracture fillings, type B with a zone of fracture fillings and an altered zone, type C consisting of several fractures with a zone of fracture fillings and an altered zone. Fracture type B was studied in detail by laboratory experiments because type B is predominant in the studied area with more than 60 % of a total of 400 fractures observed in the fracture mapping. Data from laboratory experiments on core, crosscutting a water-bearing fracture and the surrounding rock, indicate that the zone of fracture fillings and the altered zone in the vicinity of the fracture contain flow-paths in which nuclides can migrate and be trapped. The fracture fillings contain more interconnected and permeable flow-paths than the altered and unaltered zones. This implies that migrating nuclides can access flow-paths in the altered zone. The altered zone adjacent to the zone of the fracture fillings contains flow-paths such as microfractures, cracks within quartz, and grain boundaries between altered minerals, through which nuclides will migrate from the fracture fillings into the altered zone and be trapped. The fracture fillings and the specimen of the altered zone have higher sorption capacity than the specimen of the unaltered zone. These data suggest that retention of nuclides can be expected in the vicinity of the fracture. In conclusion, a conceptual flow-path model consisting of a zone of fracture fillings, an altered zone, and an unaltered zone has been developed for a better understanding of nuclide migration in fracture type B.

The “FEBEX” Project: A Demonstration and Testbench of the Spanish Concept for Crystalline Rock Repositories

1997 ◽  
Vol 506 ◽  
Author(s):  
J.L. Fuentes-Cantillana ◽  
F. Huertas ◽  
J.L. Santiago
Keyword(s):  
Test Site ◽  
Crystalline Rock ◽  
Test Length ◽  
In Situ Test ◽  
Preliminary Results ◽  
Compacted Bentonite ◽  
Automatic Mode ◽  
Grimsel Test Site ◽  
Total Test

ABSTRACTA full-scale “In situ” test is currently being conducted as part of the FEBEX project. This test is being carried out at the Grimsel Test Site in Switzerland and reproduces the “AGP-Granite” concept of the Spanish agency ENRESA for HLW repositories. Two heaters, of the same dimensions and weight as the canisters in the reference concept, have been placed in a horizontal drift of 2,28 m diameter and backfilled with a total of 115.7 t of highly compacted bentonite blocks, up to a total test length of 17 m. More than 600 sensors have been installed in the experiment, which runs basically in an automatic mode and is being remotely controlled and monitored from Spain. This paper addresses the engineering, installation and instrumentation aspects of this test. In addition, some preliminary results are shown

Preliminary field data of selected deep-rooted vegetation effects on the slope-vegetation-atmosphere interaction: results from an in-situ test 

2021 ◽  
Author(s):  
Vito Tagarelli ◽  
Federica Cotecchia ◽  
Osvaldo Bottiglieri
Keyword(s):  
Soil Water ◽  
Pore Water ◽  
Field Data ◽  
Test Site ◽  
Grass Species ◽  
In Situ Test ◽  
South Eastern ◽  
Atmosphere Interaction ◽  
The Stability

<p>The soil-vegetation-atmosphere interaction is becoming more and more the subject of intense scientific research, motivated by the wish of using smart vegetation implants as sustainable mitigation measure for erosive phenomena and slope instability processes. <br>The use of novel naturalistic interventions making use of vegetation has been already proven to be successful in the reduction of erosion along sloping grounds, or in increasing the stability of the shallow covers of slopes, whereas the success of vegetation as slope stabilization measure still needs to be scientifically proven for slopes location of deep landslides, whose current activity is climate-induced, as frequent in the south-eastern Apennines. Recently, though, peculiar natural perennial grass species, which develop deep root systems, have been found to grow in the semi-arid climate characterizing the south-eastern Apennines and to determine a strong transpirative flow. Therefore, their peculiar leaf architecture, their crop density, combined with their perennial status and transpiration capacity, make such grass species suitable for the reduction of the net infiltration rates, equal to the difference between the rainfall rate and the sum of the runoff plus the evapotranspiration rate. As such, the grass species here of reference have been selected as vegetation measure intended to determine a reduction of the piezometric levels in the slope down to large depths, in order to increase the stability of deep landslide bodies. <br>At this stage, only preliminary field data representing the interaction of clayey soils with the above cited vegetation species are available. These have been logged within a full scale in-situ test site, where the deep-rooted crop spices have been seeded and farmed. The test site (approximatively 2000 m<sup>2</sup>) has been set up in the toe area of the climate-induced Pisciolo landslide, in the eastern sector of the Southern Apennines.<br>The impact of the vegetation on the hydro-mechanical state of the soil is examined in terms of the spatial and temporal variation of the soil water content, suction an pore water pressure from ground level down to depth, both within the vegetated test site and outside it, where only spare wild vegetation occur, in order to assess the effects of the implant of the selected vegetation. The soil water contents, suctions and pore water pressures have been also analyzed taking into account of the climatic actions, monitored by means of a meteorological station. </p>

scholarly journals The seismo-hydro-mechanical behaviour during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in-situ stimulation experiment

2017 ◽  
Author(s):  
Florian Amann ◽  
Valentin Gischig ◽  
Keith Evans ◽  
Joseph Doetsch ◽  
Reza Jalali ◽  
...  
Keyword(s):  
Rock Mass ◽  
Geothermal Energy ◽  
Numerical Models ◽  
Test Site ◽  
Crystalline Rock ◽  
Coupled Processes ◽  
Small Scale ◽  
Intermediate Scale ◽  
Grimsel Test Site

Abstract. In this contribution we present a review of scientific research results that address seismo-hydro-mechanical coupled processes relevant for the development of a sustainable heat exchanger in low permeability crystalline rock and introduce the design of the In-situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site dedicated to study such processes under controlled conditions. The review shows that research on reservoir stimulation for deep geothermal energy exploitation has been largely based on laboratory observations, large-scale projects and numerical models. Observations of full-scale reservoir stimulations have yielded important results. However, the limited access to the reservoir and limitations in the control on the experimental conditions during deep reservoir stimulations is insufficient to resolve the details of the hydro-mechanical processes that would enhance process understanding in a way that aids future stimulation design. Small scale laboratory experiments provide a fundamental insights into various processes relevant for enhanced geothermal energy, but suffer from 1) difficulties and uncertainties in upscaling the results to the field-scale and 2) relatively homogeneous material and stress conditions that lead to an over-simplistic fracture flow and/or hydraulic fracture propagation behaviour that is not representative for a heterogeneous reservoir. Thus, there is a need for intermediate-scale hydraulic stimulation experiments with high experimental control that bridge the various scales, and for which access to the target rock mass with a comprehensive monitoring system is possible. Only few intermediate-scale hydro-shearing and hydro-fracturing experiments have recently been performed in a densely instrumented rock mass. No such measurements have been performed on faults in crystalline basement rocks. The In-situ Stimulation and Circulation (ISC) experiment currently performed in a naturally fractured and faulted crystalline rock mass at the Grimsel Test Site (Switzerland) is designed to address open research questions, which could not be investigated in the required detail so far. Two hydraulic injection phases were executed to enhance the permeability of the rock mass: a hydro-shearing phase and then a hydraulic fracturing phase. During the injection phases the rock mass deformation across fractures and within intact rock, the pore pressure distribution and propagation and the micro-seismic response were monitored at a high spatial and temporal resolution.

scholarly journals Eighteen years of steel–bentonite interaction in the FEBEX in situ test at the Grimsel Test Site in Switzerland

2019 ◽  
Vol 67 (2) ◽  
pp. 111-131 ◽  
Author(s):  
Jebril Hadi ◽  
Paul Wersin ◽  
Vincent Serneels ◽  
Jean-Marc Greneche
Keyword(s):  
Test Site ◽  
In Situ Test ◽  
Grimsel Test Site

scholarly journals 4D Tracer Flow Reconstruction in Fractured Rock through Borehole GPR Monitoring

2021 ◽  
Author(s):  
Peter-Lasse Giertzuch ◽  
Joseph Doetsch ◽  
Alexis Shakas ◽  
Mohammadreza Jalali ◽  
Bernard Brixel ◽  
...  
Keyword(s):  
Fractured Rock ◽  
Time Lapse ◽  
Test Site ◽  
Crystalline Rock ◽  
Flow Paths ◽  
Tracer Injection ◽  
Flow Reconstruction ◽  
Fracture Apertures ◽  
Ground Penetrating ◽  
Engineering Projects

Abstract. Two borehole ground penetrating radar (GPR) surveys were conducted during saline tracer injection experiments in fully-saturated crystalline rock at the Grimsel Test Site in Switzerland. The saline tracer is characterized by an increased electrical conductivity in comparison to formation water. It was injected under steady state flow conditions into the rock mass that features sub-mm fracture apertures. The GPR surveys were designed as time-lapse reflection GPR from separate boreholes and a time-lapse transmission survey between the two boreholes. The local increase in conductivity, introduced by the injected tracer, was captured by GPR in terms of reflectivity increase for the reflection surveys, and attenuation increase for the transmission survey. Data processing and difference imaging was used to extract the tracer signal in the reflection surveys, despite the presence of multiple static reflectors that could shadow the tracer reflection. The transmission survey was analyzed by a difference attenuation inversion scheme, targeting conductivity changes in the tomography plane. By combining the time-lapse difference reflection images, it was possible to reconstruct and visualize the tracer propagation in 3D. This was achieved by calculating the potential radially-symmetric tracer reflection locations in each survey and determining their intersections, to delineate the possible tracer locations. Localization ambiguity imposed by the lack of a third borehole for a full triangulation was reduced by including the attenuation tomography results into the analysis. The resulting tracer flow reconstruction was found to be in good agreement with data from conductivity sensors in multiple observation locations in the experiment volume and gave a realistic visualization of the hydrological processes during the tracer experiments. Our methodology proved to be successful for characterizing flow paths related with geothermal reservoirs in crystalline rocks, but it can be transferred in a straightforward manner to other applications, such as radioactive repository monitoring or civil engineering projects.

Sand/Bentonite Barriers and Gas Migration: The GMT Large-Scale In-Situ Test in the Grimsel Test Site

2002 ◽  
Vol 757 ◽  
Author(s):  
S. Vomvoris ◽  
B. Lanyon ◽  
P. Marschall ◽  
K. Ando ◽  
T. Adachi ◽  
...  
Keyword(s):  
Large Scale ◽  
Test Site ◽  
Intermediate Level ◽  
Test Sequence ◽  
Gas Migration ◽  
Migration Test ◽  
In Situ Test ◽  
Grimsel Test Site ◽  
Engineered Barrier

ABSTRACTThe Gas Migration Test in the engineered barrier system (GMT) investigates the migration of waste-generated gas from low and intermediate level waste in a silo-type disposal concept. The EBS has now been emplaced and saturation was initiated in August 2001. The saturation patterns show heterogeneity within and between different layers of the EBS. Plans for the remaining test sequence are also presented.

scholarly journals The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment

Solid Earth ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 115-137 ◽  
Author(s):  
Florian Amann ◽  
Valentin Gischig ◽  
Keith Evans ◽  
Joseph Doetsch ◽  
Reza Jalali ◽  
...  
Keyword(s):  
Rock Mass ◽  
Geothermal Energy ◽  
Numerical Models ◽  
Test Site ◽  
Crystalline Rock ◽  
Coupled Processes ◽  
Small Scale ◽  
Homogeneous Material ◽  
Grimsel Test Site

Abstract. In this contribution, we present a review of scientific research results that address seismo-hydromechanically coupled processes relevant for the development of a sustainable heat exchanger in low-permeability crystalline rock and introduce the design of the In situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site dedicated to studying such processes under controlled conditions. The review shows that research on reservoir stimulation for deep geothermal energy exploitation has been largely based on laboratory observations, large-scale projects and numerical models. Observations of full-scale reservoir stimulations have yielded important results. However, the limited access to the reservoir and limitations in the control on the experimental conditions during deep reservoir stimulations is insufficient to resolve the details of the hydromechanical processes that would enhance process understanding in a way that aids future stimulation design. Small-scale laboratory experiments provide fundamental insights into various processes relevant for enhanced geothermal energy, but suffer from (1) difficulties and uncertainties in upscaling the results to the field scale and (2) relatively homogeneous material and stress conditions that lead to an oversimplistic fracture flow and/or hydraulic fracture propagation behavior that is not representative of a heterogeneous reservoir. Thus, there is a need for intermediate-scale hydraulic stimulation experiments with high experimental control that bridge the various scales and for which access to the target rock mass with a comprehensive monitoring system is possible. The ISC experiment is designed to address open research questions in a naturally fractured and faulted crystalline rock mass at the Grimsel Test Site (Switzerland). Two hydraulic injection phases were executed to enhance the permeability of the rock mass. During the injection phases the rock mass deformation across fractures and within intact rock, the pore pressure distribution and propagation, and the microseismic response were monitored at a high spatial and temporal resolution.

Radionuclide geochemistry evolution in the Long-term In-situ Test (LIT) at Grimsel Test Site (Switzerland)

2021 ◽  
pp. 127733
Author(s):  
Vanessa Montoya ◽  
Ulrich Noseck ◽  
Felix Mattick ◽  
Susan Britz ◽  
Ingo Blechschmidt ◽  
...  
Keyword(s):  
Test Site ◽  
In Situ Test ◽  
Grimsel Test Site

The Study of Radionuclide Retardation in Fractured Rock by Means of In Situ Resin Impregnation

1997 ◽  
Vol 506 ◽  
Author(s):  
W. Russell Alexander ◽  
Christoph Bühler ◽  
Hannes Dollinger ◽  
Bernhard Frieg ◽  
Paul Haag ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Shear Zone ◽  
Laboratory Data ◽  
Acrylic Resin ◽  
Test Site ◽  
Crystalline Rock ◽  
Rock Matrix ◽  
Resin Impregnation ◽  
Water Saturated

ABSTRACTTraditional in situ tracer tests estimate contaminant retardation by analysis of the degree and form of tracer breakthrough after transport through the rock. Unfortunately, this approach does not allow direct examination of in situ retardation mechanisms and, in the case of strongly retarded radionuclides, is highly impractical as tracer breakthrough may take months to decades. An alternative method to study retardation is therefore required in such a case and Nagra and PNC have recently employed one such variant to study radionuclide transport in fractured crystalline rock. Here, direct, detailed, examination of in situ radionuclide retardation following tracer injection is carried out by immobilising and recovering the intact fracture and associated rock matrix [1,2].The material can then be studied in the laboratory by standard surface analytical and radiochemical methods and the degree and form of radionuclide uptake can be readily assessed.As part of this work, Nagra and PNC have invested significant effort over the last four years in developing appropriate means of immobilising water-conducting fractures and undisturbed low porosity crystalline rock matrix in a manner which minimises physico-chemical disturbance[3]. After examining a range of options, it was decided to employ in situ resin impregnation as the immobilisation medium as this produced the best results with respect to minimising physico-chemical disturbance of the system while at the same time ensuring impregnation of very fine water saturated pore space. In addition, the polymerised resins improve the rigidity and strength of the rock such that the water saturated structures (pores, fractures or fault gouges) survive the subsequent overcoring and sub-sampling.Two experiments will be discussed: the first has been recently completed in Nagra's underground laboratory in the central Swiss Alps (the Grimsel Test Site, or GTS) and the second is currently ongoing at PNC's Kamaishi In Situ Test Site (KTS) in north-east Japan.In the GTS, retardation of radionuclides is being studied in the Radionuclide Retardation Project (RRP) and two resins have been formulated for different aspects of the study. An epoxy resin has been injected into a complex water-conducting shear zone in a granodiorite following the injection of a cocktail of strongly retarding radionuclides (including 60Co, 237Np, 234. 235U, 99Tc, 152Eu, 113Sn and 75Se [1,2]). To negate the hydrophobic nature of the epoxy resin, a trick has been imported from soil science where isopropanol is first injected to replace the water and only then is the epoxy resin injected. Laboratory tests showed that neither the isopropanol nor the resin should disturb the in situ radionuclide distribution, a result which has since been verified in the field. In parallel with this work, the low porosity (<1%) granodiorite rock matrix behind the shear zone is being examined by means of an in situ injection of an acrylic resin. The very low viscosity of the specially developed acrylic resin allows impregnation (and subsequent visualisation) of the connected microporosity of the matrix, so allowing detailed in situ examination of the depth of available matrix behind the shear zone.These methods have been further refined in the KTS and are currently being applied to several different types of water conducting features. The form and type of connected porosity in the associated granodioritic rock matrix is also being examined in detail [4]. As with the GTS work, the results of the in situ experiments will be compared with laboratory data on retardation and matrix diffusion to assess the transferability of the large volume of laboratory data to the field.The development of the various resins will be discussed along with the applicability of these specially developed resins to other rock types. Finally, the results of the recently concluded GTS tests and the ongoing KTS tests will be presented.

scholarly journals Search for underground openings for in situ test facilities in crystalline rock

1980 ◽  
Author(s):  
H.A. Wollenberg ◽  
B. Strisower ◽  
D.J. Corrigan ◽  
A.N. Graf ◽  
M.T. O'Brien ◽  
...  
Keyword(s):  
Crystalline Rock ◽  
In Situ Test ◽  
Underground Openings
Sign in / Sign up

Export Citation Format

Share Document