Corrosion of ISG by Mg-Si precipitation in presence of Ankerite

Dabbas, Ali Al; Kopecskó, Katalin

doi:10.1556/606.2021.00410

Cited by 3 publications

(3 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the pH affects precipitation and maintains balance with the strange components supplied by geological formation. All of these factors, which have been demonstrated and discussed in previous studies [13,33,34], impact the HLW's durability, which should be considered.…”

Section: Resultsmentioning

confidence: 89%

Investigation of silicic acid saturation and gel formation during ISG leaching: 180 days duration reaction at 90 °C

Dabbas

Kopecskó

2022

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

Currently, borosilicate glasses are utilised to immobilise highly radioactive waste. They are durable materials; however, they corrode in aqueous solutions, resulting in silica-rich alteration layers. This study employed the nuclear waste leaching tests (MCC-1, MCC-3) on International Simple Glass (ISG) samples. The corrosion rate in pure water and saturated water with respect to ISG corrosion products was investigated at an initial pH of 6.3 and a reaction temperature of 90 °C. For 3, 7, 14, 28, 90, and 180 days, batch experimental models with extremely high and very low glass surface area to volume (S/V) ratios were examined. The results showed that early saturation in the higher S/V system resulted in a ten order magnitude reduced corrosion rate compared to the lower S/V system. This emphasises the significance of saturation in achieving a reduced corrosion rate. This research proved the significant influence of the solution’s chemistry on the glass corrosion rate via pH and other chemical parameters.

show abstract

Section: Resultsmentioning

confidence: 89%

Investigation of silicic acid saturation and gel formation during ISG leaching: 180 days duration reaction at 90 °C

Dabbas

Kopecskó

2022

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Significant Mg appearance can be observed in G-1 M and G-2 M samples, which shows a decreasing trend towards G-3 M. This phenomenon can be explained by Mg-silicate precipitation, which can be realized by the presence of magnesium in the leaching solution (Table 2). This phase is limited by the glass alteration kinetics and a pH above 8 is required for the phase formation 20,33 . The pH of the leachates was 12.48, 9.64 and 8.91, for G-1 M, G-2 M and G-3 M, respectively.…”

Section: X-ray Photoelectron Spectroscopy For Glass Surface Character...mentioning

confidence: 99%

Glass/steel/clay interactions in a simulated radioactive waste geological disposal system

Tolnai,

Osan,

Czompoly

et al. 2023

Sci Rep

View full text Add to dashboard Cite

Deep geological storage is the accepted solution for the final disposal of high-level radioactive waste therefore, it is necessary to study the host rock of the planned Hungarian waste repository and the materials involved in the engineered barriers. The main goal was to understand the characteristics and stability of the glass/steel/claystone system, from the structural properties of the vitrified waste (borosilicate glasses) to the clay response in the repository. Repository conditions were applied during the experiments to understand the chemical evolution of the system. A triplicate setup was kept at 80 °C for 3, 7 and 12 months and post-mortem characterization was performed. No alteration products were observed with scanning electron microscopy energy dispersive X-ray spectroscopy measurements on the surface of the glass and Fe or in the clay after the end of the experimental period. Based on the elemental analysis of the liquid phase, the released amount of B, K, Si and Na increased, while that of Ca and Mg decreased compared to the baseline. The concentrations of Cl− and SO42− did not change significantly. Ca- and Mg-silicate precipitation was observed by X-ray photoelectron spectroscopy at the surface range of the borosilicate glasses because of the synthetic porewater treatment.

show abstract

“…Numerous studies, performed either at laboratory scale or long-term in situ experiments and geochemical modeling, reported the migration of Mg in the bentonite to the hottest zones near the canister surface [18]. That caused the enrichment in Mg at the canister-bentonite interface, allowing interaction with ions in solution like Fe 2+ , Fe 3+ , Na + , K + or Ca 2+ , and forming minerals like saponite, chlorite group or ankerite (Ca(Fe 2+ ,Mg)(CO 3 ) 2 ) [37,44,50]. Mg enrichment in bentonite has also been observed by diffusion towards the alkaline interface of cement-based materials used as engineered barriers in some DGR concepts [6,51,52].…”

Section: Introductionmentioning

confidence: 99%

Geochemical Evolution of Mg-Bentonite Affected by the Contact of Carbon Steel and a Hydrothermal Gradient

Mota-Heredia,

Cuevas,

Fernández

2024

Applied Sciences

View full text Add to dashboard Cite

Carbon steel and bentonite are materials selected as engineered barriers for high-level radioactive waste confinement. Their long-term interaction must be evaluated to confirm the barrier’s stability. Three laboratory experiments of the carbon steel—Mg-bentonite interaction were conducted for 1, 6, and 22 months under a hydrothermal gradient. Changes in bentonite’s water content, specific surface area, and cation exchange capacity were measured. Mineralogy was studied by X-ray diffraction and scanning electron microscopy. The redistribution of aqueous species and the redox state of iron were determined across the bentonite columns. Results indicated water saturation after 22 months. The specific surface area of bentonite was reduced near contact with the steel, while the cation exchange capacity mostly decreased at 3–6 mm from the steel interface. The corrosion rate decreased with time and bentonite enriched in Fe in the first 1.5 mm from the steel contact. The formation of new Fe-bearing minerals, such as di-tri ferri-sudoite, magnetite, hematite, maghemite, lepidocrocite, siderite and ankerite was observed. Aqueous species redistributed in the porewater of bentonite with decreasing concentrations of Fe and Cl as a function of time and increasing concentrations of Na, Ca and SO4 after 22 months. This occurs under conditions where the bentonite is saturated with Mg, which conditioned the formation and nature of iron clay minerals with time.

show abstract

Corrosion of ISG by Mg-Si precipitation in presence of Ankerite

Cited by 3 publications

References 29 publications

Investigation of silicic acid saturation and gel formation during ISG leaching: 180 days duration reaction at 90 °C

Investigation of silicic acid saturation and gel formation during ISG leaching: 180 days duration reaction at 90 °C

Glass/steel/clay interactions in a simulated radioactive waste geological disposal system

Geochemical Evolution of Mg-Bentonite Affected by the Contact of Carbon Steel and a Hydrothermal Gradient

Contact Info

Product

Resources

About