Bentonite barrier materials and the control of microbial processes: Safety case implications for the geological disposal of radioactive waste

Haynes, Haydn M.; Bailey, Matthew T.; Lloyd, Jonathan R.

doi:10.1016/j.chemgeo.2021.120353

Cited by 17 publications

(3 citation statements)

References 103 publications

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“…For example, the evidence that microbial activity is suppressed by highly compacted bentonite or cementitious backfill is largely empirical ( [169,170,180,181] for compacted bentonite and [182] cementitious backfill). While research in this area still continues [183,184], it would seem that the most important factors limiting microbial activity in highly compacted bentonite are the high swelling pressure, low water activity, and the lack of physical space or a combination of all three.…”

Section: Empiricalmentioning

confidence: 99%

Review of the Modelling of Corrosion Processes and Lifetime Prediction for HLW/SF Containers—Part 1: Process Models

King,

Kolàř,

Briggs

et al. 2024

CMD

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The disposal of high-level radioactive waste (HLW) and spent nuclear fuel (SF) presents a unique challenge for the prediction of the long-term performance of corrodible structures since HLW/SF containers are expected, in some cases, to have lifetimes of one million years or longer. Various empirical and deterministic models have been developed over the past 45 years for making predictions of long-term corrosion behaviour, including models for uniform and localised corrosion, environmentally assisted cracking, microbiologically influenced corrosion, and radiation-induced corrosion. More recently, fracture-mechanics-based approaches have been developed to account for joint mechanical–corrosion degradation modes. Regardless of whether empirical or deterministic models are used, it is essential to be able to demonstrate a thorough mechanistic understanding of the corrosion processes involved. In addition to process models focused on specific corrosion mechanisms, there is also a need for performance-assessment models as part of the overall demonstration of the safety of a deep geological repository. Performance-assessment models are discussed in Part 2 of this review.

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Section: Empiricalmentioning

confidence: 99%

Review of the Modelling of Corrosion Processes and Lifetime Prediction for HLW/SF Containers—Part 1: Process Models

King,

Kolàř,

Briggs

et al. 2024

CMD

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“…Bacteria cultured from FEBEX samples were able to grow at 70 °C, but these culturing techniques only indicate that bacteria had remained viable, not whether they were actively growing during the experiment. The increasing relative abundance of Cyanobacteria towards the heater suggests increased inactivity with higher temperatures, as Cyanobacteria are photosynthetic and could not have grown in situ (Haynes et al 2021 ). Further, viable cell counts (calculated from the most probable number technique) were low near the heating element (Bengtsson et al 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Extremophilic microbial metabolism and radioactive waste disposal

Butterworth,

Barton,

Lloyd

2023

Extremophiles

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Decades of nuclear activities have left a legacy of hazardous radioactive waste, which must be isolated from the biosphere for over 100,000 years. The preferred option for safe waste disposal is a deep subsurface geological disposal facility (GDF). Due to the very long geological timescales required, and the complexity of materials to be disposed of (including a wide range of nutrients and electron donors/acceptors) microbial activity will likely play a pivotal role in the safe operation of these mega-facilities. A GDF environment provides many metabolic challenges to microbes that may inhabit the facility, including high temperature, pressure, radiation, alkalinity, and salinity, depending on the specific disposal concept employed. However, as our understanding of the boundaries of life is continuously challenged and expanded by the discovery of novel extremophiles in Earth’s most inhospitable environments, it is becoming clear that microorganisms must be considered in GDF safety cases to ensure accurate predictions of long-term performance. This review explores extremophilic adaptations and how this knowledge can be applied to challenge our current assumptions on microbial activity in GDF environments. We conclude that regardless of concept, a GDF will consist of multiple extremes and it is of high importance to understand the limits of polyextremophiles under realistic environmental conditions.

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“…Another essential aspect of an effective buffer material is its ability to inhibit microbial activity. Properly designed bentonite with low permeability should prevent the transport of microbes and the essential nutrients they require for growth [16,18]. Additionally, the swelling pressure generated during bentonite supersaturation can exert stress on any microbial cells present by increasing pore pressure.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Water/Cement/Bentonite Ratio Used for Construction of Cut-Off Walls

Barbu,

Sabău,

Manoli

et al. 2023

Buildings

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In recent years, because of the continuous expansion of urban areas, an increased necessity to isolate historically polluted sites by means of artificial, flexible, low-permeability barriers has emerged. Moreover, due to cost and efficiency considerations, various combinations of materials that fulfill the previously stated requirements have been proposed. On the basis of a literature review, this paper analyses the relationships between water, cement, and bentonite, and the physical and mechanical properties of the resulting material created in combination with standard sand introduced in the mixture using a ratio of 2:1 with respect to the solid part of the mixture (cement and bentonite). The quantity of standard sand was established following previous research conducted by the authors. The relation between water, cement, and bentonite is analyzed through properties such as viscosity, permeability, and undrained cohesion, and the representation of mixtures and their corresponding parameters was carried out using a ternary diagram. This paper provides a graphical approach to finding the optimum water/bentonite/cement mixture required for barrier design, taking into account permeability, undrained cohesion, and mixture viscosity.

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Bentonite barrier materials and the control of microbial processes: Safety case implications for the geological disposal of radioactive waste

Cited by 17 publications

References 103 publications

Review of the Modelling of Corrosion Processes and Lifetime Prediction for HLW/SF Containers—Part 1: Process Models

Review of the Modelling of Corrosion Processes and Lifetime Prediction for HLW/SF Containers—Part 1: Process Models

Extremophilic microbial metabolism and radioactive waste disposal

Analysis of the Water/Cement/Bentonite Ratio Used for Construction of Cut-Off Walls

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