scholarly journals Mineralogical Analysis of Bentonite from the ABM5 Heater Experiment at Äspö Hard Rock Laboratory, Sweden

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 669
Author(s):  
Stephan Kaufhold ◽  
Reiner Dohrmann ◽  
Kristian Ufer ◽  
Daniel Svensson ◽  
Patrik Sellin
Keyword(s):  
Hard Rock ◽  
Mineralogical Analysis ◽  
Rock Laboratory ◽  
Bentonite Buffer ◽  
Higher Temperature ◽  
High Temperature Reactions ◽  
Mg Content ◽  
First Time ◽  
Dissolution And Precipitation ◽  
Deposition Test

The present study reports on the analysis of all blocks of the ABM5 test, which is a medium scale bentonite buffer deposition test. In contrast to similar tests, the ABM5 was conducted at higher temperature (up to 250 °C). The aim of the study was to characterize the chemical and mineralogical reactions and to identify the effect of the extraordinarily high temperature. Reactions observed were similar to those observed in previous and/or similar tests covering cation exchange, anion inflow, dissolution and precipitation of C- and S-phases, Fe corrosion, and Mg increase at the heater. Neither the type nor the extent of the different reactions could be related to the significantly higher temperature. However, due to the absence of lubricant used between heater and bentonite, it could be proved that the calcite previously present was dissolved and precipitated as siderite at the contact, pointing towards the importance of the presence of carbonate when considering different Fe corrosion products. Moreover, for the first time, a decrease of the Mg content at the heater was observed, which was probably because a Mg-rich clay was used. The reasons for Mg increase or decrease are still not completely understood.

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

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.

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 Siderophore Production by Pseudomonas stutzeri under Aerobic and Anaerobic Conditions

2007 ◽  
Vol 73 (18) ◽  
pp. 5857-5864 ◽  
Author(s):  
Sofia A. Essén ◽  
Anna Johnsson ◽  
Dan Bylund ◽  
Karsten Pedersen ◽  
Ulla S. Lundström
Keyword(s):  
Mass Spectrometry ◽  
Hard Rock ◽  
Bacterial Culture ◽  
Pseudomonas Stutzeri ◽  
Siderophore Production ◽  
Anaerobic Conditions ◽  
Rock Laboratory ◽  
Molecular Masses ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT The siderophore production of the facultative anaerobe Pseudomonas stutzeri, strain CCUG 36651, grown under both aerobic and anaerobic conditions, was investigated by liquid chromatography and mass spectrometry. The bacterial strain has been isolated at a 626-m depth at the Äspö Hard Rock Laboratory, where experiments concerning the geological disposal of nuclear waste are performed. In bacterial culture extracts, the iron in the siderophore complexes was replaced by gallium to facilitate siderophore identification by mass spectrometry. P. stutzeri was shown to produce ferrioxamine E (nocardamine) as the main siderophore together with ferrioxamine G and two cyclic ferrioxamines having molecular masses 14 and 28 atomic mass units lower than that of ferrioxamine E, suggested to be ferrioxamine D2 and ferrioxamine X1, respectively. In contrast, no siderophores were observed from anaerobically grown P. stutzeri. None of the siderophores produced by aerobically grown P. stutzeri were found in anaerobic natural water samples from the Äspö Hard Rock Laboratory.

Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis

2018 ◽  
Vol 74 (5) ◽  
pp. 623-627 ◽  
Author(s):  
Sviatoslav Baranets ◽  
Hua He ◽  
Svilen Bobev
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Diffraction Data ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Reactions ◽  
First Time ◽  
Synthetic Work

Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb0.92(1)NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

scholarly journals Permeability Enhancement and Fracture Development of Hydraulic In Situ Experiments in the Äspö Hard Rock Laboratory, Sweden

2018 ◽  
Vol 52 (2) ◽  
pp. 495-515 ◽  
Author(s):  
Günter Zimmermann ◽  
Arno Zang ◽  
Ove Stephansson ◽  
Gerd Klee ◽  
Hana Semiková
Keyword(s):  
Hard Rock ◽  
Permeability Enhancement ◽  
Rock Laboratory ◽  
Fracture Development ◽  
In Situ Experiments

A geoscientific site descriptive model for the Äspö Hard Rock Laboratory, SE Sweden

2021 ◽  
Author(s):  
Jesper Petersson ◽  
Peter Hultgren ◽  
Mansueto Morosini ◽  
Frédéric Mathurin
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Hard Rock ◽  
Saline Water ◽  
Regional Scale ◽  
Building Blocks ◽  
Special Focus ◽  
Low Grade ◽  
Descriptive Model ◽  
Rock Laboratory

<p>The development of an updated geoscientific site descriptive model (SDM) is currently in progress for the Äspö Hard Rock Laboratory (Äspö HRL), the key underground research facility of the Swedish Nuclear Fuel and Waste Management Company (SKB). Äspö HRL is located in south-eastern Sweden, within a suite of 1.81–1.76 Ga granitoids, and consists of a tunnel system down to 460 m depth with a total length of about 5 km. Tectonically, the area is part of a contractional shear belt, primarily manifested by a NE-SW trending regional deformation zone, which partly transect the underground facility. The shear zone system has evolved gradually over a prolonged period, with an initial low-grade ductile development, followed by multiple events of brittle reactivation. The structural framework is characterised by a significant heterogeneity in the hydraulic flow properties, where the most transmissive structures belong to a set of less extensive, conjugate zones and fractures.</p><p>More than 30 years of studies, starting with the pre-investigations and construction of the facility, have generated a wealth of geoscientific data in 3-D space, and hence a sound basis for an update of existing models. The SDM under current development aims to present an integrated geoscientific understanding of the Äspö site, with special focus on geology, hydrogeology and hydrogeochemistry. The general working procedure includes basically an initial stage of data capture, followed by an intermediate interpretative stage, and finally the construction of 3-D models with associated concepts and parameters. An explicit goal throughout the work has been to encourage interaction between the different geo-disciplines, especially during the interpretative stage, as a forerunner to the final stage of deterministic/conceptual modelling. During the interpretative stage, geological and geophysical information were combined into two basic building blocks along individual boreholes, tunnels, and outcrops: rock units and possible deformation zones, which were assigned hydraulic parameters such as primarily K-values. The subsequent geological 3-D modelling comprises two components: rock domains and deformation zones with a surface trace length of ≥ 300 m. Hydrogeological feedback was provided in terms of K-anisotropies and depth trends.</p><p>The fundamental outcome of the modelling is a more profound conceptual understanding, along with geometries and properties for each domain or zone. Additional outcomes are data on and understanding of the effects of 25 years of artificial tunnel drainage on groundwater pressures, flow and chemistry. The natural groundwater system, originally formed by paleoclimatic and geological factors over a vast period, has be profoundly influenced by important monitored phenomena. Upflow of deep-lying saline water and extensive intrusion of current seawater disclose the apparent hydro-properties and interconnection between deformation zones.</p><p>Currently, geological 3-D model includes geometries for ten rock domains and 24 deformation zones, the latter with seamless transitions to zones of the regional scale Laxemar model, as developed by the SKB with the objective of siting a geological repository for spent nuclear fuel in the proximity to the Äspö HRL. As completed, the models will serve as framework for more detailed-scaled facility models.</p>

The Use of Natural Uranium Decay Series Studies in Support of Understanding Redox Conditions at Potential Radioactive Waste Disposal Sites

2003 ◽  
Vol 807 ◽  
Author(s):  
Eva-Lena Tullborg ◽  
John A. T. Smellie ◽  
Angus B. MacKenzie
Keyword(s):  
Radioactive Waste ◽  
Sensitive Element ◽  
Hard Rock ◽  
Natural Uranium ◽  
Radioactive Waste Disposal ◽  
Redox Conditions ◽  
Series Data ◽  
Last Glaciation ◽  
Rock Laboratory ◽  
Decay Series

ABSTRACTUranium is a redox-sensitive element which occurs naturally in the bedrock and groundwaters in Fennoscandia, and can be used, in conjunction with its decay series descendants, to indicate groundwater redox conditions. Not only can contemporary conditions be characterised, but evidence of past changes (e.g. during the last glaciation some 10 ka ago) can be preserved in minerals which coat the fracture walls along groundwater pathways. Uranium decay series data for groundwaters and solid fracture phases from the site of the Äspö Hard Rock Laboratory and its near vicinity are presented and discussed in the context of redox conditions.

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