Modelling the Prototype Repository

2018 ◽  
Vol 482 (1) ◽  
pp. 241-260 ◽  
Author(s):  
V. Tsitsopoulos ◽  
S. Baxter ◽  
D. Holton ◽  
J. Dodd ◽  
S. Williams ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Host Rock ◽  
Hard Rock ◽  
Task Force ◽  
Fractured Rock ◽  
Fracture Network ◽  
Atmospheric Conditions ◽  
Predictive Capability ◽  
Rock Laboratory ◽  
Modelling Methodology

AbstractThe Prototype Repository (PR) tunnel is located at the Äspö Hard Rock Laboratory near Oskarshamn in the southeast of Sweden. In the PR tunnel, six full-sized deposition holes (8.37 m deep and 1.75 m in diameter) have been constructed. Each deposition hole is designed to mimic the Swedish reference system for the disposal of nuclear fuel, KBS-3V. The PR experiment is designed to provide a full-scale simulation of the emplacement of heat-generating waste. There are three phases to the experiment: (1) the open tunnel phase following construction, where both the tunnel and deposition holes are open to atmospheric conditions; (2) the emplacement of canisters (containing heaters), backfill and seal in the first section of the tunnel; and (3) the emplacement of canisters, backfill and seal in the second section of the tunnel. This work describes the numerical modelling, performed as part of the engineered barrier systems (EBS) Task Force, to understand the thermo-hydraulic (TH) evolution of the PR experiment and to provide a better understanding of the interaction between the fractured rock and bentonite surrounding the canister at the scale of a single deposition tunnel. A coupled integrated TH model for predicting the wetting and the temperature of bentonite emplaced in fractured rock was developed, accounting for the heterogeneity of the fractured rock. In this model, geometrical uncertainties of fracture locations are modelled by using several stochastic realizations of the fracture network. The modelling methodology utilized information available at early stages of site characterization and included site statistics for fracture occurrence and properties, as well as proposed installation properties of the bentonite. The adopted approach provides an evaluation of the predictive capability of models, it gives an insight of the uncertainties to data and demonstrates that a simplified equivalent homogeneous description of the fractured host rock is insufficient to represent the bentonite resaturation.

In situ tracer tests to determine retention properties of a block scale fracture network in granitic rock at the Äspö Hard Rock Laboratory, Sweden

2004 ◽  
Vol 70 (3-4) ◽  
pp. 271-297 ◽  
Author(s):  
Peter Andersson ◽  
Johan Byegård ◽  
Eva-Lena Tullborg ◽  
Thomas Doe ◽  
Jan Hermanson ◽  
...  
Keyword(s):  
Hard Rock ◽  
Granitic Rock ◽  
Tracer Tests ◽  
Fracture Network ◽  
Rock Laboratory

Dual-Permeability Modeling of Capillary Diversion and Drift Shadow Effects in Unsaturated Fractured Rock

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
Clifford K. Ho ◽  
Bill W. Arnold ◽  
Susan J. Altman
Keyword(s):  
Fractured Rock ◽  
Constitutive Relations ◽  
Water Flux ◽  
Fracture Network ◽  
Small Scale ◽  
Grid Refinement ◽  
Capillary Pressures ◽  
And Behavior ◽  
Capillary Pressure Curves ◽  
The Impact

The drift-shadow effect describes capillary diversion of water flow around a drift or cavity in porous or fractured rock, resulting in lower water flux directly beneath the cavity. This paper presents computational simulations of drift-shadow experiments using dual-permeability models, similar to the models used for performance assessment analyses of flow and seepage in unsaturated fractured tuff at Yucca Mountain. Comparisons were made between the simulations and experimental data from small-scale drift-shadow tests. Results showed that the dual-permeability models captured the salient trends and behavior observed in the experiments, but constitutive relations (e.g., fracture capillary-pressure curves) can significantly affect the simulated results. Lower water flux beneath the drift was observed in both the simulations and tests, and fingerlike flow patterns were seen to exist with lower simulated capillary pressures. The dual-permeability models used in this analysis were capable of simulating these processes. However, features such as irregularities along the top of the drift (e.g., from roof collapse) and heterogeneities in the fracture network may reduce the impact of capillary diversion and drift shadow. An evaluation of different meshes showed that at the grid refinement used, a comparison between orthogonal and unstructured meshes did not result in large differences.

scholarly journals Viruses in granitic groundwater from 69 to 450 m depth of the Äspö hard rock laboratory, Sweden

2008 ◽  
Vol 2 (5) ◽  
pp. 571-574 ◽  
Author(s):  
Jennifer E Kyle ◽  
Hallgerd S C Eydal ◽  
F Grant Ferris ◽  
Karsten Pedersen
Keyword(s):  
Hard Rock ◽  
Rock Laboratory ◽  
Granitic Groundwater

scholarly journals Electric resistivity and seismic refraction tomography, a challenging joint underwater survey at Äspö Hard Rock Laboratory

2016 ◽  
Author(s):  
Mathias Ronczka ◽  
Kristofer Hellman ◽  
Thomas Günther ◽  
Roger Wisen ◽  
Torleif Dahlin
Keyword(s):  
Nuclear Power ◽  
Hard Rock ◽  
Seismic Refraction ◽  
Three Dimensional ◽  
Test Site ◽  
Fracture Zones ◽  
Rock Laboratory ◽  
Refraction Tomography ◽  
Local Point ◽  
General Test

Abstract. Tunnelling below water passages is a challenging task in terms of planning, pre-investigation and construction. Fracture zones in the underlying bedrock lead to low rock quality and thus reduced stability. For natural reasons they tend to be more frequent at water passages. Ground investigations that provide information of the subsurface are necessary prior to the construction phase, but can be logistically difficult. Geophysics can help close the gaps between local point information and produce subsurface images. An approach that combines seismic refraction tomography and electrical resistivity tomography has been tested at the Äspö Hard Rock Laboratory (HRL). The aim was to detect fracture zones in a well-known but logistically and, from a measuring perspective, challenging area. The presented surveys cover a water passage along a part of a tunnel that connects surface facilities with an underground test laboratory. The tunnel is approximately 100 m below and 20 m east of the survey line and gives evidence for one major and several minor fracture zones. The geological and general test site conditions, e.g. with strong powerline noise from the nearby nuclear power plant, are challenging for geophysical measurements. Co-located positions for seismic and ERT sensors and source positions are used on the 450 m long underwater section of the 700 m long profile. Because of a large transition zone that appeared in the ERT result and the missing coverage of the seismic data, fracture zones at the southern and northern part of the underwater passage cannot be detected by separated inversion. A simple synthetic study shows significant three dimensional artefacts corrupting the ERT model that have to be taken into account while interpreting the results. A structural coupling cooperative inversion approach is able to image the northern fracture zone successfully. In addition, previously unknown sedimentary deposits with a significant large thickness are detected in the otherwise unusually well documented geological environment. The results significantly improve imaging of some geologic features, which would have been not detected or misinterpreted otherwise, and combines the images by means of cluster analysis to a conceptual subsurface model.

scholarly journals Measuring Pressure Drop Under Non Ideal Conditions

2006 ◽  
Vol 22 (1) ◽  
pp. 6-12
Author(s):  
M Austin
Keyword(s):  
Pressure Drop ◽  
Environmental Effects ◽  
Task Force ◽  
Measurement Procedure ◽  
Measuring Instrument ◽  
Atmospheric Conditions ◽  
Measurement Instruments ◽  
Cigarette Filter ◽  
Calibration Methods ◽  
Method Of Measurement

AbstractThe method of measurement of the pressure drop (PD) of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1). This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.In 2001, the Cooperation Center for Scientific Research Relative to Tobacco (CORESTA) formed a Task Force to investigate the problems associated with the calibration of PD transfer standards that are caused, primarily, by environmental effects. The work of this task force has lead to the harmonisation of the calibration methods between supplier laboratories and to a method for compensation for the effects of atmospheric conditions. These together have considerably reduced the inter-laboratory differences and will eventually lead to a revision of the CORESTA Recommended Method and ISO 6565 Standard.During the work of this Task Force, it has become evident that further work will be necessary to deal with similar errors encountered during the calibration of PD measurement instruments and during the PD measurement of cigarette and filter rod samples. These errors occur in real measurement situations due to the problems in meeting the ISO 6565 conditions and other necessary requirements. This can give rise to errors in the indicated PD and can considerably degrade the confidence that can be placed in the results.This paper examines many of the practical problems in the measurement of PD and attempts to estimate the type and magnitude of the errors that might be experienced.

scholarly journals A methodology of re-generating a representative element volume of fractured rock mass

2020 ◽  
Vol 71 (4) ◽  
pp. 347-358
Author(s):  
DANG Hong-Lam ◽  
THINH Phi Hong
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fracture Network ◽  
Hydraulic Calculation ◽  
Fractured Rock Mass ◽  
Fracture Characteristics ◽  
Mechanical Calculation ◽  
Representative Element ◽  
Representative Element Volume ◽  
Actual Fracture

In simulation of fractured rock mass such as mechanical calculation, hydraulic calculation or coupled hydro-mechanical calculation, the representative element volume of fractured rock mass in the simulating code is very important and give the success of simulation works. The difficulties of how to make a representative element volume are come from the numerous fractures distributed in different orientation, length, location of the actual fracture network. Based on study of fracture characteristics of some fractured sites in the world, the paper presented some main items concerning to the fracture properties. A methodology of re-generating a representative element volume of fractured rock mass by DEAL.II code was presented in this paper. Finally, some applications were introduced to highlight the performance as well as efficiency of this methodology.

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