scholarly journals In situ corrosion of canister materials in bentonite: the IC-A experiment at Mont Terri

2021 ◽  
Vol 1 ◽  
pp. 89-89
Author(s):  
Nikitas Diomidis ◽  
Bharti Reddy
Keyword(s):  
Carbon Steel ◽  
Corrosion Product ◽  
Corrosion Properties ◽  
Microbially Influenced Corrosion ◽  
Welding Steel ◽  
Anaerobic Corrosion ◽  
Mont Terri ◽  
Underground Research Laboratory

Abstract. Since 2012, a long-term in situ corrosion experiment (IC-A) has been conducted in the Mont Terri Underground Research Laboratory in Switzerland. The aims of the project with international partners are to confirm the long-term anaerobic corrosion rate of carbon steel and copper in compacted bentonite under repository-relevant environmental conditions, to gather in situ corrosion data supporting canister lifetime predictions, to provide confirmation of the effect of the bentonite buffer on microbial activity and microbially influenced corrosion, and to study the effects of welding (steel) and deposition technique (copper) on the corrosion properties of these candidate materials for disposal canisters. To date, carbon steel and cold sprayed and electrodeposited copper coatings have been retrieved after different exposure periods up to 3 years and characterised to establish the composition of the corrosion product, the morphology of the corroded surface, and to measure the rate of corrosion. For carbon steel specimens, a complex corrosion product was identified, consisting predominantly of magnetite. Low average anaerobic corrosion rates were measured for carbon steel and a very modest amount of alteration was identified on copper. The density and the initial form of the bentonite had a small influence on the rate of corrosion, across all materials.

scholarly journals Comparison between in situ and laboratory diffusion studies of HTO and halides in Opalinus Clay from the Mont Terri

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Etienne Tevissen ◽  
J. M. Soler ◽  
P. Montarnal ◽  
A. Gautschi ◽  
Luc R. Van Loon
Keyword(s):  
Tritiated Water ◽  
Opalinus Clay ◽  
Diffusion Experiment ◽  
Diffusion Technique ◽  
Diffusion Studies ◽  
Through Diffusion ◽  
Mont Terri

SummaryA long-term single-borehole diffusion experiment (DI) using tritiated water (HTO) and stable iodide (All HTO results obtained with a through diffusion technique are within the same range as those obtained in the

Tiltmeter Measurements at the Underground Rock Laboratory in Mont Terri

2020 ◽  
Author(s):  
Dorothee Rebscher
Keyword(s):  
Decadal Variability ◽  
Opalinus Clay ◽  
Earthquake Activity ◽  
Rock Laboratory ◽  
In Situ Experiments ◽  
First Results ◽  
Mont Terri ◽  
Mont Terri Rock Laboratory

<p>Mont Terri rock laboratory, located in the Swiss Jurassic Mountains, was established with the focus on the investigation and analysys of the properties of argillaceous formations. The scope of Opalinus Clay as a safe, potential option for nuclear waste disposal was broaden, as the behaviour of claystone is of high interest also in the context of caprocks, and hence, for many dynamical processes in the subsurfaces. Extensive research has been performed already for more than 20 years by the partners of the Mont Terri Consortium. These close cooperations cover a broad range of scientific aspects using numerical modelling, laboratory studies, and last not least in-situ experiments. Here, included in the long-term monitoring programme, new investigations apply tiltmeters. Since April 2019, platform tiltmeters have been installed at various locations within the galleries and niches of Mont Terri. The biaxial instruments have resolutions of 1 nrad and 0.1 µrad, respectively (Applied Geomechanics and Lippmann Geophysikalische Messgeräte). The tilt measurements are embedded within various experiments contributing to specific, multiparametrical studies. However, the growing tilt network as a whole will also provide novel information of the rock laboratory. The different time-scales of interest include long-term observations of yearly and decadal variability. So far tilt signals were identified due to excavations during the recent enlargement of the laboratory, earthquake activity (Albania), and local effects. First results of these quasi-continuous recordings will be presented.</p>

Long Term Corrosion Behaviour of Carbon Steel During Anaerobic to Aerobic Cycling Under Near-Neutral pH Saline Conditions

2010 ◽  
Author(s):  
Brent W. A. Sherar ◽  
Peter G. Keech ◽  
Zack Qin ◽  
Fraser King ◽  
David W. Shoesmith ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Focused Ion Beam ◽  
Corrosion Behaviour ◽  
Ion Beam ◽  
Cycle Number ◽  
Corrosion Rates ◽  
Anaerobic Corrosion ◽  
Film Porosity ◽  
Electrochemical Microscopy

This paper investigates the long term corrosion behaviour of pretreated carbon steel under alternating anaerobic to aerobic cycles over 238 days. Changes in steel behaviour were observed electrochemically by monitoring the corrosion potential, and calculating changes to corrosion rate from linear polarization resistance. With increasing cycle number the corrosion process becomes localized at a small number of locations, consistent with the formation of tubercles. Periods of aerobic corrosion were associated with more positive potentials (between −500 mV to −350 mV) and high corrosion rates (70 to 120 μm yr−1); whereas anaerobic corrosion yielded more negative potentials (< −650 mV) and lower corrosion rates (40 to 50 μm yr−1). Upon termination of the experiment, corrosion product deposits were characterized by several techniques: scanning electrochemical microscopy to detect morphology; focused ion beam and cross sectioning to judge film thickness and film porosity; and Raman Spectroscopy to identify iron phases.

Corrosion processes and microbial activity of carbon steel in the context of geological repository in clay environment

MRS Advances ◽  
2016 ◽  
Vol 1 (63-64) ◽  
pp. 4185-4191 ◽  
Author(s):  
Sophia Necib ◽  
Christian Bataillon ◽  
Sylvie Daumas ◽  
Michel L. Schlegel ◽  
Didier Crusset
Keyword(s):  
Carbon Steel ◽  
Metal Surface ◽  
Electrochemical Impedance ◽  
Thermophilic Bacteria ◽  
Test Chamber ◽  
Opalinus Clay ◽  
High Level Waste ◽  
High Level ◽  
Mont Terri ◽  
Underground Research Laboratory

ABSTRACTCarbon steel (C-steel) is studied to be the reference material for the metallic components in the high level waste (HLW) repository concepts of several European countries such as France, Switzerland, Belgium.Electrochemical impedance spectroscopy (EIS) was performed over a period of 7 years, to determine the instantaneous corrosion rate (CR) of carbon steel (C-steel) in contact with clay porewater in diffusive regime. The study was conducted at the Mont Terri underground research laboratory (URL) located in Switzerland. The test chamber was at a depth of 8 m under anoxic conditions at 90°C in a vertical and descending borehole drilled in Opalinus clay (OPA). Microbial and chemical investigations were conducted on porewater in contact with C-steel as well as directly on C-steel surface further to dismantling.The results showed clearly a decrease of the CR over time followed by a steady state below 1 µm/year. Sulphate and thiosulphate reducing bacteria were observed in porewater and at the metal surface, with a higher concentration of mesophilic and thermophilic bacteria respectively. The metal surface characterizations revealed the presence of magnetite, mackinawite, hydroxychloride and siderite with local traces of oxidizing species such as goethite.

scholarly journals Anaerobic corrosion of carbon steel in compacted bentonite exposed to natural Opalinus clay porewater: Bentonite alteration study

2021 ◽  
Vol 1 ◽  
pp. 103-104
Author(s):  
Nikoleta Morelová ◽  
Kathy Dardenne ◽  
Nicolas Finck ◽  
Frank Heberling ◽  
Volker Metz ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Steel Corrosion ◽  
Opalinus Clay ◽  
Spectroscopic Techniques ◽  
Clay Rocks ◽  
Corrosion Mechanisms ◽  
High Level ◽  
Mont Terri ◽  
Underground Research Laboratory ◽  
Term Performance

Abstract. Carbon steel is a potential canister material for the disposal of high-level radioactive waste in deep geological repositories in clays and clay rocks. Bentonite is considered as a potential backfill material for those multi-barrier systems. To predict the long-term performance and for safety assessment the knowledge of canister corrosion behavior is important. The corrosion products formed and mineralogically altered bentonite at the canister/bentonite interface can potentially provide an additional barrier against radionuclide migration. In-situ corrosion experiments were performed at the Mont Terri underground research laboratory. Coupons of carbon steel were embedded in Volclay MX-80 bentonite with controlled densities, installed in a borehole under simulated repository and anaerobic conditions and exposed to natural Opalinus clay porewater for a period up to 5.5 years (Smart et al., 2017). In the present study, the bentonite layer at the canister/bentonite interface was characterized by complementary microscopic and spectroscopic techniques (XPS, SEM-EDX, µXANES) under anoxic conditions. The interface revealed reddish-brown staining up to 2 mm depth into the bentonite in the zone adjacent to the steel in all three obtained samples. The XPS analysis revealed formation of sulfides at the interface consisting of iron and other trace metals present in the steel. The SEM-EDX analyses of the interface (embedded cross-cut with steel removed) showed different degrees of calcium enrichment in the bentonite adjacent to the metal for various samples. The µXRF analysis performed on the bentonite at the interface showed a scarce or distinct calcium-enriched rim up to 100 µm into the bentonite and iron-enriched rim depending on the sample (one sample in Fig. 1), while µXANES analysis revealed formation of iron silicate compounds in the reacted reddish-brown zone. The iron appears to displace calcium from the interlayer sites in montmorillonite. The calcium then precipitates at the interface as calcite. The extent of this process seems to be strongly related to the bentonite density. The steel coupon was removed prior to embedding, with the location marked as resin in Fig. 1. A line scan from the edge towards the bulk bentonite did not indicate any systematic gradient in the Fe2+/3+ ratio. The formation of mixed Fe2+/3+ silicate compounds appears to be heterogeneous. This work contributes to an increasing understanding of steel corrosion mechanisms in clay, which can improve the robustness of canister lifetime predictions.

scholarly journals Mathematical Modelling of Fault Reactivation Induced by Water Injection

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 282 ◽  
Author(s):  
Thanh Son Nguyen ◽  
Yves Guglielmi ◽  
Bastian Graupner ◽  
Jonny Rutqvist
Keyword(s):  
Induced Seismicity ◽  
Water Injection ◽  
In Situ Stress ◽  
Fault Reactivation ◽  
Shear Strength Parameters ◽  
Radionuclide Migration ◽  
Strength Parameters ◽  
Mont Terri ◽  
Underground Research Laboratory

Faults in the host rock that might exist in the vicinity of deep geological repositories for radioactive waste, constitute potential enhanced pathways for radionuclide migration. Several processes might trigger pore pressure increases in the faults leading to fault failure and induced seismicity, and increase the faults’ permeability. In this research, we developed a mathematical model to simulate fault activation during an experiment of controlled water injection in a fault at the Mont-Terri Underground Research Laboratory in Switzerland. The effects of in-situ stress, fault shear strength parameters and heterogeneity are assessed. It was shown that the above factors are critical and need to be adequately characterized in order to predict the faults’ hydro-mechanical behaviour.

scholarly journals Monitoring the Corrosion of Steel in Concrete Exposed to a Marine Environment

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 407 ◽  
Author(s):  
Nina Gartner ◽  
Tadeja Kosec ◽  
Andraž Legat
Keyword(s):  
Carbon Steel ◽  
Marine Environment ◽  
Corrosion Damage ◽  
Corrosion Monitoring ◽  
Corrosion Properties ◽  
Aisi 304L ◽  
Key Issues ◽  
Corrosion Mechanisms ◽  
Chloride Contaminated

Reinforced concrete structures require continuous monitoring and maintenance to prevent corrosion of the carbon steel reinforcement. In this work, concrete columns with carbon and stainless steel reinforcements were exposed to a real marine environment. In order to monitor the corrosion processes, two types of corrosion probes were embedded in these columns at different height levels. The results from the monitoring of the probes were compared to the actual corrosion damage in the different exposure zones. Electrical resistance (ER) probes and coupled multi-electrodes (CMEs) were shown to be promising methods for long-term corrosion monitoring in concrete. Correlations between the different exposure zones and the corrosion processes of the steel in the concrete were found. Macrocell corrosion properties and the distribution of the separated anodic/cathodic places on the steel in chloride-contaminated concrete were addressed as two of the key issues for understanding the corrosion mechanisms in such environments. The specific advantages and limitations of the tested measuring techniques for long-term corrosion monitoring were also indicated. The results of the measurements and the corrosion damage evaluation clearly confirmed that the tested stainless steels (AISI 304 and AISI 304L) in a chloride-contaminated environment behave significantly better than ordinary carbon steel, with corrosion rates from 110× to 9500× lower in the most severe (tidal) exposure conditions.

Simulation of The State of Carbon Steel n Years After Disposal with n Years of Corrosion Product on its Surface in a Bentonite Environment

1994 ◽  
Vol 353 ◽  
Author(s):  
Yoichi Kojima ◽  
Toshinobu Hioki ◽  
Shigeo Tsujikawa
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Steel Corrosion ◽  
Product Layer ◽  
The State ◽  
Corrosion Product Layer ◽  
Time Frames

AbstractThe use of bentonite as buffer and carbon steel as overpack material for the geological disposal of nuclear waste is under investigation. To better assess the long term integrity of the carbon steel overpack, a quantitative analysis of the corrosion behavior on the steel surface for time frames beyond that of feasible empirical determination is required. The state n years after disposal, consisting of Carbon Steel / Corrosion Products + Bentonite / Water, was simulated and the corrosion behavior of the carbon steel in this state investigated. The following facts became apparent. Both the corrosion rate and the non-uniformity of it increased with increase in the corrosion product content in the compacted bentonite. When the corrosion product layer was formed between the carbon steel and the bentonite, it ennobled the corrosion potential and increased the corrosion rate.

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