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.

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 New Aromatic Azo-Schiff as Carbon Steel Corrosion Inhibitor in 1 M H2SO4

2018 ◽  
Vol 34 (5) ◽  
pp. 2471-2476 ◽  
Author(s):  
Hamida Edan Salman ◽  
Asim A. Balakit ◽  
Ali Ahmed Abdulridha
Keyword(s):  
Weight Loss ◽  
Carbon Steel ◽  
Corrosion Inhibitor ◽  
Corrosion Inhibition ◽  
Potentiodynamic Polarization ◽  
Inhibition Efficiency ◽  
Steel Corrosion ◽  
Spectroscopic Techniques ◽  
Different Temperatures ◽  
Corrosion Inhibition Efficiency

A new aromatic Schiff base with azo linkage (AS) has been synthesized and characterized by FT-IR, 1H NMR and 13C NMR spectroscopic techniques. The new compound (AS) has been evaluated as carbon steel corrosion inhibitor at different concentrations (0.005, 0.01, 0.02, 0.04 and 0.08 mM) and different temperatures (303 – 333 K). The corrosion inhibition efficiency was studied by potentiodynamic polarization and weight loss measurements. The effects of concentration and temperature on the inhibition efficiency were studied by potentiodynamic polarization studies, the results showed that increasing concentration of AS increases the inhibition efficiency while increasing the temperature decreases it, the highest corrosion inhibition efficiency, 93.9% was recorded with 0.08 mM of AS at 313 K in 1 M H2SO4. Weight loss measurements showed that the inhibition efficiency reached 97.1% in the presence of AS (0.08 mM) at 313 K. The adsorption process was found to obey Langmuir isotherm, and the adsorption thermodynamic parameters were studied. Scanning electron microscope (SEM) was used to confirm the results.

scholarly journals Impact of the heterogeneity of the sandy Opalinus clay facies at the Mont Terri underground research laboratory on radionuclide migration

2021 ◽  
Vol 1 ◽  
pp. 141-142
Author(s):  
Naila Ait-Mouheb ◽  
Yuankai Yang ◽  
Luc R. Van Loon ◽  
Martin A. Glaus ◽  
Guido Deissmann ◽  
...  
Keyword(s):  
Research Laboratory ◽  
Radioactive Wastes ◽  
Coupled Processes ◽  
Opalinus Clay ◽  
Nuclear Waste Repository ◽  
Radionuclide Transport ◽  
Mont Terri ◽  
Underground Research Laboratory ◽  
Host Rocks ◽  
The Impact

Abstract. The assessment of the safety of a deep geological repository (DGR) for high-level radioactive wastes over assessment time scales of up to 1 million years requires an in-depth understanding of the multi-scale coupled processes that affect the repository system evolution over time, to reduce uncertainties and conservatism in safety analyses. This is in particular required with respect to the challenges of a comparative assessment of different repository concepts in different host rocks within the process of a site selection for a DGR for heat-generating radioactive wastes in Germany. The collaborative project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCross)” conducted jointly by five research centres of the Helmholtz Association and co-funded by the Initiative and Networking Fund of the Helmholtz Association and the Federal Ministry of Education and Research (BMBF) has been initiated with the overall objective to improve the understanding of coupled thermal-hydraulic-mechanical-chemical-(micro)biological (THMCB) processes and to develop simulation tools that enable a holistic close to reality description of the long-term evolution of the repository system. Geological formations, such as those foreseen as potential host rocks for DGRs, and their surroundings are heterogeneous on various length scales ranging from nanometers to kilometers. Therefore, the aim of this work in the context of iCross is to evaluate the effects of mineralogical, geochemical and microstructural heterogeneities of repository host rocks on radionuclide transport in the repository far field, using the sandy facies of the Opalinus clay (SF-OPA) from the Mont Terri underground research laboratory (St. Ursanne, Switzerland) as an example. Here, we address in particular the migration behaviour of Ra-226 as an important radionuclide to be considered in safety cases for deep geological disposal of spent nuclear fuel. To assess the impact of the heterogeneities in SF-OPA on radionuclide transport, a complementary approach combining microstructural characterisation methods, experimental techniques for the determination of transport parameters of the rock matrix and the mobility of Ra-226 with innovative developments in reactive transport modelling on the pore and continuum scales was pursued. One of the results was that although the limited clay content in SF-OPA decreases the total amount of Ra bound to the illite phase, the solid solutions of sulphate and carbonate compensate for this and provide a major fixation mechanism.

A Review of 25 years of Corrosion Studies on HLW Container Materials at the CEA

2006 ◽  
Vol 985 ◽  
Author(s):  
Max Helie
Keyword(s):  
Carbon Steel ◽  
Base Alloy ◽  
Atomic Energy Commission ◽  
Propagation Rate ◽  
High Level Waste ◽  
Corrosion Resistant ◽  
Nickel Base ◽  
Corrosion Mechanisms ◽  
High Level

ABSTRACTThe Commissariat à l'Énergie Atomique (CEA, French Atomic Energy Commission) has been involved in researches on nuclear waste management for more than 25 years. One of the key issues is the prediction of the long term behavior and aging of the High Level Waste (HLW) containers in order to develop concepts that will ensure the confinement of the activity over extremely long periods of time.Preliminary studies were carried out on two concepts, one of a thin "corrosion resistant" container made of titanium or nickel base alloy, and the other on a thick "corrosion allowance" container made or carbon steel.The results of these experiments showed that the "corrosion resistant" concept led to a high uncertainty on the development and propagation rate of localized forms of corrosion, and the concept of geological disposal in an argillaceous host formation of thick waste containers made of carbon steel was chosen as the reference. Studies are still in progress to better assess the corrosion mechanisms relevant to this situation in order to provide reliable models for the long term prediction of the containers corrosion behavior.

Investigation of Corrosion Mechanisms in a Continuous Catalytic Regeneration (CCR) Platformer Unit

2019 ◽  
Vol 797 ◽  
pp. 393-401 ◽  
Author(s):  
Nur Balqis Rusli ◽  
Najmiddin Yaakob ◽  
Robert Mikhail Savory
Keyword(s):  
Carbon Steel ◽  
Oil And Gas ◽  
Cooling System ◽  
Steel Corrosion ◽  
Oil And Gas Industry ◽  
High Resistivity ◽  
Alloy 800H ◽  
Gas Industry ◽  
Ultimate Failure ◽  
Corrosion Mechanisms

— Corrosion is prevalent throughout the world, none less so than in the oil and gas industry. Managing and mitigating corrosion in refining complexes is of paramount importance in order to prevent undesirable consequences such as major fires, explosions and Boiling Liquid Expanding Vapor Explosion (BLEVE) due to Loss of Primary Containment caused by the thinning and ultimate failure of pipelines and vessel walls. Analysis of a platformer unit at a Malaysian refinery has identified the occurrence of thermal fatigue and erosion corrosion on the Vent Gas Tower (VGT) Caustic Circulation line, which in turn has led to the excessive degradation of the walls of a venturi scrubber and the 8’’ caustic circulation line with initial thickness of 12.70mm. The rate of corrosion (0.88 mm/year) of the 8’’ caustic circulation line exceeds the standard allowable carbon steel corrosion rate (0.1 mm/year) as stated in API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry. This indicates that the circulation line has significant potential to fail which would lead to a major HSE incident. Based on these findings it is recommended that the refinery in question modifies the line by increasing the thickness of the line and include a cooling system to reduce temperature swing (ΔT) to below 93°C. Besides that, it is suggested that the implementation of Corrosion-Resistant Alloys (CRA) is conducted on the line. According to ASME B31.3 and supported by ASTM A 193, the line can be replaced with nickel-based alloy, alloy 800H and killed carbon steel which have high resistivity to corrosion than carbon steel. However, more comprehensive studies need to be conducted to identify the viable mitigation methods that are suitable to be implemented on the Vent Gas Tower (VGT) Caustic Circulation line.

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.

Microbiological research program in deep HRW repository «Yeniseisky»: plans and first results

2021 ◽  
Author(s):  
Alexey Safonov ◽  
Elena Abramova ◽  
Nadezhda Popova ◽  
Grigory Artemiev ◽  
Kirill Boldyrev
Keyword(s):  
Activation Energy ◽  
Carbon Steel ◽  
Radioactive Waste ◽  
Steel Corrosion ◽  
Granite Gneiss ◽  
Water Radiolysis ◽  
Near Surface ◽  
Barrier Materials ◽  
High Level ◽  
Clay Materials

<p>The concept of engineered geologic disposal has been developed for the safe long-term management of long-lived high-level radioactive waste (HRW) by many countries. Russian Federation evaluates the “Yeniseiskiy” Nizhnekansky granite-gneiss crystalline formation, in Krasnoyarsk region. To this date microbiological studies became an integral part of safety assessment in Russia like other countries.</p><p>A multi-barrier concept was used to create super-container (SC). SC contains a primary vitrified radioactive waste package, placed in the carbon steel casing, bentonite and aluminate concrete layers placed between the casing and inner IC surface. All selected barrier materials are potential areas for biogenic processes.</p><p>The talk presented a plan of experimental research of biogenic processes and first step results. Microbiological studies at the first stage are carried out in laboratory conditions, at the second stage they will be carried out under the conditions of URL and include:</p><p>- changes of host rock sorption and diffusion properties due to biofilms formation,</p><p>- assessment of the possibility biocolloidal particles formation and determination clay and ferruginous colloids stability during biogenic processes;</p><p>To date, the study of the phylogenetic and functional diversity of the microflora of the granite-gneiss massif, near-surface waters, and clay materials that will be used in disposal has been carried out. It has been established that microorganisms, isolated from samples, collected nearby the zone of the future repository are capable of participating in a number of undesirable processes, including steel corrosion acceleration, the formation of biogenic gases, and changes in the properties of clay materials. Our studies also show that microbial communities of clays are activated by hydrogen, which is a product of steel corrosion and water radiolysis. At the first stage, we found an increase in the corrosion of carbon steel in the presence of microorganisms sampled from the study area.</p><p>An acceleration of the corrosion rate of carbon steel (from 1.3 to 1.9 μm/year) was observed with an increase in temperature from 20 to 50<sup>0</sup>С, the calculated value of the activation energy was 22 kJ/mol * K. Based on the data obtained, a kinetic model of carbon steel corrosion in the presence of microorganisms was created, including both the inclusion of the activation energy and the inhibition of corrosion by the formed corrosion products.</p><p> </p>

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