Multiple-barrier geological repository design and operation strategies for safe disposal of radioactive materials

Apted, M.J.; Ahn, Joonhong

doi:10.1533/9781845699789.1.3

Cited by 14 publications

(8 citation statements)

References 14 publications

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“…Besides the Mont Terri URL in Switzerland, a number of underground laboratories in other countries and their potential or selected host rock formations are in operation, mainly in crystalline rocks (e.g., Äspö Hard Rock Laboratory in Sweden) and plastic or indurated clays (e.g., HADES URL in Belgium, Meuse/Haute-Marne URL and Tournemire URL in France) (Blechschmidt and Vomvoris, 2010;Delay et al, 2014). Similar to the Opalinus Clay in Switzerland, the EDZ and its impact on the hydromechanical characteristics of the rock mass in the near field of underground structures are of particular interest for the Callovo-Oxfordian claystone in France (e.g., Armand et al, 2014;Baechler et al, 2011;Menaceur et al, 2016) and for the Boom Clay in Belgium (e.g., Bastiaens et al, 2007;Dao et al, 2015).…”

Section: S Hale Et Al: Mechanical and Hydraulic Properties Of An Edzmentioning

confidence: 99%

“…In the field, hydraulic properties can be derived from hydraulic or pneumatic borehole tests (Aoyagi and Ishii, 2019;Jakubick and Franz, 1993;de La Vaissière et al, 2015;Shao et al, 2008). Mechanical fracture apertures can generally be obtained by different fracture imaging methods, whereby visibility can be improved by injecting dyed or fluorescent resin into the fractured rock (Armand et al, 2014;Bossart et al, 2002).…”

Section: S Hale Et Al: Mechanical and Hydraulic Properties Of An Edzmentioning

confidence: 99%

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Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

Hale

Ries

Jaeggi³

et al. 2021

Solid Earth

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Abstract. Construction of cavities in the subsurface is always accompanied by excavation damage. Especially in the context of deep geological nuclear waste disposal, the evolving excavation damaged zone (EDZ) in the near field of emplacement tunnels is of utmost importance concerning safety aspects. As the EDZ differs from the intact host rock due to enhanced hydraulic transmissivity and altered geomechanical behavior, reasonable and location-dependent input data on hydraulic and mechanical properties are crucial. Thus, in this study, a hydromechanical characterization of an EDZ in the Mont Terri underground rock laboratory, Switzerland, was performed using three different handheld devices: (1) air permeameter, (2) microscopic camera and (3) needle penetrometer. The discrete fracture network (DFN), consisting of artificially induced unloading joints and reactivated natural discontinuities, was investigated by a portable air permeameter and combined microscopic imaging with automatic evaluation. Geomechanical and geophysical characterization of the claystone was conducted based on needle penetrometer testing at the exposed rock surface. Within the EDZ, permeable fractures with a mean hydraulic aperture of 84 ± 23 µm are present. Under open conditions, self-sealing of fractures is suppressed, and cyclic long-term fracture aperture oscillations in combination with closure resulting from convergence processes is observed. Based on measured needle penetration indices, a uniaxial compressive strength of 30 ± 13 MPa (normal to bedding) and 18 ± 8 MPa (parallel to bedding) was determined. Enhanced strength and stiffness are directly related to near-surface desaturation of the claystone and a sharp decrease in water content from 6.6 wt % to 3.7 wt %. The presented methodological approach is particularly suitable for time-dependent monitoring of EDZs since measurements are nondestructive and do not change the actual state of the rock mass. This allows for a spatially resolved investigation of hydraulic and mechanical fracture apertures, fracture surface roughness, and physico-mechanical rock parameters and their intra-facies variability.

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Section: S Hale Et Al: Mechanical and Hydraulic Properties Of An Edzmentioning

confidence: 99%

Section: S Hale Et Al: Mechanical and Hydraulic Properties Of An Edzmentioning

confidence: 99%

Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

Hale

Ries

Jaeggi³

et al. 2021

Solid Earth

View full text Add to dashboard Cite

show abstract

“…Generally, deep geological repositories are considered to be the safest available option for long-term storage for up to one million years. [1][2][3] Such DOI: 10.1002/adts.202300406 repositories incorporate a multi-barrier system to ensure that the radiotoxic material will not be released into the biosphere. The multi-barrier system can be separated into the engineered barrier and the host rock.…”

Section: Introductionmentioning

confidence: 99%

Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes

Schabernack,

Oliveira,

Heine

et al. 2023

Advcd Theory and Sims

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In deep geological repositories for nuclear waste, the surrounding rock formation serves as an important barrier against radionuclide migration. Multiple potential host rocks contain phyllosilicates, which have shown high efficiency in radionuclide sorption. Recent experimental studies report a heterogeneous distribution of adsorbed radionuclides on nanotopographic mineral surfaces. In this study, the energetic differences of surface sorption sites available at nanotopographic structures such as steps, pits, and terraces are investigated. Eleven important surface sites are selected and the energies of ad‐ and desorption reactions are obtained from density functional theory calculations. The adsorption energies are then used for the parameterization of a kinetic Monte Carlo model simulating the distribution of adsorbed europium on a typical nanotopographic muscovite surface. On muscovite, silicon step sites are favorable for europium sorption and lead to an increased adsorption in regions with high step concentrations. Under identical chemical conditions, sorption on typical nanotopographic surfaces is increased by a factor of three compared to atomically flat surfaces. Desorption occurs preferentially at terrace sites, leading to an overall 2.5 times increased retention at nanotopographic structures. This study provides a mechanistic explanation for heterogeneous sorption on nanotopographic mineral surfaces due to the availability of energetically favorable sorption sites.

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“…The safety of such repositories must be guaranteed for time periods longer than the history of homo sapiens 4. The safety relies on a series of natural and engineered barriers preventing the highly radioactive material from migrating into the biosphere5. In some repository concepts, metallic copper has been proposed as an outer corrosion resistant barrier on canisters containing the spent nuclear fuel678.…”

Section: Introductionmentioning

confidence: 99%

Gamma radiation induces hydrogen absorption by copper in water

Lousada

Soroka

Yagodzinskyy

et al. 2016

Sci Rep

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One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.

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Multiple-barrier geological repository design and operation strategies for safe disposal of radioactive materials

Cited by 14 publications

References 14 publications

Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes

Gamma radiation induces hydrogen absorption by copper in water

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