Summary of studies on the anaerobic corrosion of carbon steel in alkaline media in support of the Belgian supercontainer concept

Smart, N.R.; Rance, A.P.; Nixon, D. J.; Fennell, P.A.H.; Reddy, B. S. R.; Kursten, Bruno

doi:10.1080/1478422x.2017.1356981

Cited by 17 publications

(23 citation statements)

References 6 publications

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“…This was assumed to represent the full mass of hydrogen generated during the accumulation period (i.e., no hydrogen was dissolved in the electrolyte, or absorbed by the steel specimens, and the purge gas was sufficient to expel all hydrogen from the cell). It was also assumed that the corrosion was uniform, the surface area was unchanging, and that, given sufficient time, the reaction stoichiometry was described in total by

3 normalF normale + 4 H_{2} O \to {Fe}_{3} {normalO}_{4} + 4 H_{2}

17 . Regarding stainless steel, the contribution of alloying elements and thus the reaction stoichiometry will be updated to match the composition of the actual corrosion products upon dismantling of the test cells.…”

Section: Methodsmentioning

confidence: 99%

The corrosion of mild and stainless steel in alkaline anaerobic conditions representing the Belgian “supercontainer” concept and the Swiss L/ILW repository

Senior

Martino

Diomidis

2020

Materials & Corrosion

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Deep geological repositories for radioactive waste contain metallic materials, either used to construct disposal canisters or as low-/intermediate-level waste (L/ILW). The safety relevance of corrosion is linked to canister lifetime in the former case and gas generation in the latter. More specifically, the Belgian "supercontainer" concept envisages mild steel for the used fuel disposal canister, and in the case of the Swiss L/ILW repository, mild steels are the largest metallic waste component due to the decommissioning of civilian powergenerating facilities. For these circumstances, the corrosion environment is dominated by the chemistry of cement, which is used as buffer or backfill material. The corrosion behaviour of mild steel in anoxic environments was studied through the analysis of the hydrogen end-product. Hydrogen analysis was conducted by periodically purging the cell head-space and analysing the gas using a solid-state hydrogen sensor. While this method is limited to providing only uniform corrosion rates averaged over periods of time, ranging from weeks to months, it provides excellent resolution and sensitivity. The test cell environments were matched against the anticipated Belgian high-level waste and Swiss L/ILW repository environments, and also against experiments that have been conducted by other researchers for comparative purposes. Samples were exposed to synthetic cement pore waters, representing fresh and degraded cement. In young cement waters, the formation of initial corrosion products resulted in steel wire corrosion rates of the order of µm/year, which, at 80°C rapidly declined to ∼10 nm/year. In contrast, SA516 grade 70 steel plate corroded much more slowly under similar conditions. In aged cement waters, initial corrosion rates were higher but declined faster towards a longerterm rate of ∼10 nm/year. 316L stainless steel, embedded in cementitious material, corroded at a rate of <1 nm/year at 50°C.

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3 normalF normale + 4 H_{2} O \to {Fe}_{3} {normalO}_{4} + 4 H_{2}

Section: Methodsmentioning

confidence: 99%

The corrosion of mild and stainless steel in alkaline anaerobic conditions representing the Belgian “supercontainer” concept and the Swiss L/ILW repository

Senior

Martino

Diomidis

2020

Materials & Corrosion

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“…The Fe(OH) 2 is stable at lower temperatures, but it is predicted to convert to the more thermodynamically stable magnetite (Fe 3 O 4 ) by the Schikorr reaction at higher temperature [19]. The anaerobic corrosion of carbon steel was studied in artificial ground waters and in alkaline solutions [18,29]. Analysis of long-term corrosion tests under a range of conditions, including cementitious environments, found Fe 3 O 4 to be the predominant corrosion product [18].…”

Section: Of 17mentioning

confidence: 99%

“…The anaerobic corrosion of carbon steel was studied in artificial ground waters and in alkaline solutions [18,29]. Analysis of long-term corrosion tests under a range of conditions, including cementitious environments, found Fe 3 O 4 to be the predominant corrosion product [18]. Results for the amount of hydrogen generated depend on which iron corrosion product is used.…”

Section: Of 17mentioning

confidence: 99%

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Corrosion Performance of Engineered Barrier System in Deep Horizontal Drillholes

Payer

Finsterle²,

Apps³

et al. 2019

Energies

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The disposal of spent nuclear fuel and other high-level radioactive waste in deep horizontal drillholes is an innovative system. Canisters of highly corrosion-resistant nickel-chromium-molybdenum (Ni-Cr-Mo) alloys are specified for the disposal of this nuclear waste. The canisters are emplaced along a steel casing in a horizontal drillhole that is one to three kilometers deep into or below a low-permeability geologic formation. The drillhole is in fully saturated rock with anoxic and reducing pore waters. A time-interval analysis method was used to track the evolution of the environment and to analyze corrosion performance of a representative engineered barrier system (EBS) configuration. In this analysis, the canisters remained perforation-free for tens of thousands of years. The amounts of hydrogen and metal oxides formed as by-products of the metal corrosion process were determined. These by-products are of interest, because both hydrogen and metal oxides can affect the chemical composition of the environment and the transport and sorption behavior of radionuclides and other species. Beneficial attributes that contribute to the extraordinarily long life of the canisters were identified. Several inherent characteristics of the horizontal drillhole disposal system reduced the complexities and uncertainties of the analysis.

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“…Initially, the specimens underwent a short period of rapid corrosion, followed by a drop in the rate to a low and stable value of around 100–200 nm/year. Smart et al [ 11 ] observed that the long‐term corrosion rates of carbon steel under such conditions were insensitive to various environmental parameters including temperature and chloride concentration. The surface analysis was completed on carbon steel wires extracted anoxically from high pH test environments and magnetite was found to be the predominant corrosion product; however, evidence of FeOOH was also found on wires once embedded in cementitious material.…”

Section: Introductionmentioning

confidence: 99%

The anoxic corrosion behaviour of carbon steel in anoxic alkaline environments simulating a Swiss L/ILW repository environment

Senior

Martino

Diomidis

2020

Materials & Corrosion

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The Swiss waste management programme foresees that low‐ and intermediate‐level radioactive waste will be disposed of in a deep geological repository constructed in Opalinus Clay. Gas generation is expected in the repository due to the decomposition of organic materials and the corrosion of metals, with carbon steel being the primary source. The corrosion behaviour of mild steel under anoxic conditions has been studied over the course of several years to better understand the long‐term hydrogen evolution profile under anticipated repository conditions. Steel, either bare or encased within mortar, was tested in water vapour or immersed in electrolytes representative of aged cement waters at 50°C. The corrosion rate was measured indirectly through the hydrogen analysis using a solid‐state probe. The hydrogen evolution behaviour of grout was also monitored to more accurately determine the hydrogen generating from the corrosion of the embedded steel. For steel in water vapour or in alkaline environments, embedded in cementitious material or immersed in simulated aged cement pore water, corrosion rates were invariably <1 nm/year after several years of analysis.

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Summary of studies on the anaerobic corrosion of carbon steel in alkaline media in support of the Belgian supercontainer concept

Cited by 17 publications

References 6 publications

The corrosion of mild and stainless steel in alkaline anaerobic conditions representing the Belgian “supercontainer” concept and the Swiss L/ILW repository

The corrosion of mild and stainless steel in alkaline anaerobic conditions representing the Belgian “supercontainer” concept and the Swiss L/ILW repository

Corrosion Performance of Engineered Barrier System in Deep Horizontal Drillholes

The anoxic corrosion behaviour of carbon steel in anoxic alkaline environments simulating a Swiss L/ILW repository environment

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