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Economic and Legal Aspects of Power Generation and the Environment
Published in Anco S. Blazev, Power Generation and the Environment, 2021
The most advanced waste nuclear depository project is the Onkalo spent nuclear fuel repository, which presently under construction in Finland. It is a deep geological repository designed for the final disposal of spent nuclear fuel. Based on the KBS-3 method of nuclear waste burial, developed in Sweden, the Onkalo facility’s constructions plans are divided into four phases: Phase one was focused on excavation of the large access tunnel to the facility, spiraling downward to a depth of 1,380 ft.Phase two continued the excavation to a final depth of 1,710 ft. The characteristics of the bedrock were studied to adapt the layout of the repository.Phase three marks the construction of the repository, which is expected to begin around 2015, after the completion of the initial investigation and the design plans.Phase four, the encapsulation and burial of areas filled with spent fuel is projected to begin around 2020.
Hydro-mechanical modelling of an unsaturated seal structure
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
D.F. Ruiz, J. Vaunat, A. Gens, M.A. Mánica
The design of a deep geological repository for high-level nuclear waste must include sealing systems to ensure the isolation of the connecting galleries, ramps and shafts of the facility after the end of the operational phase.
Hydro-mechanical modelling of an unsaturated seal structure
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
D.F. Ruiz, J. Vaunat, A. Gens, M.A. Mánica
The design of a deep geological repository for high-level nuclear waste must include sealing systems to ensure the isolation of the connecting galleries, ramps and shafts of the facility after the end of the operational phase.
Thermal Conductivity Estimation of Compacted Bentonite Buffer Materials for a High-Level Radioactive Waste Repository
Published in Nuclear Technology, 2018
Seok Yoon, Min-Jun Kim, Seung-Rae Lee, Geon-Young Kim
Deep geological repository systems aim toward the safe disposal of spent fuel by isolating the spent fuel in rock layers 500 to 1000 m below the ground surface, based on the concept of an engineered barrier system (EBS). The EBS in a deep geological repository consists of a canister, backfill, buffer, and near-field rock. Spent fuel rods are stored in canisters that are made of strong metals that resist corrosion and physical impact and are then placed in a cave-shaped deep geological repository site constructed in solid rock.4,5 The canister is then sealed with the buffer. There may be gaps between the canister and buffer and between the buffer and wall of near-field rock. Accordingly, gap filling materials are then installed in order to maintain thermal contact from the canister to the buffer.3 In addition, the cave-shaped repository is completely sealed with the backfill to create a seal of several layers thickness in all directions to ensure isolation from the ecosystem (Fig. 1). Not only does the buffer—filled in between the canister and the disposal—act to secure the canister in place, but also it protects the canister from physical impact due to the shear behavior of the rock and minimizes the inflow of groundwater to prevent leakage of radionuclides to neighboring rock areas through groundwater.6–8 In addition, as the thermal properties of the buffer allow rapid dissipation of the decayed heat from the canister to the rock nearby, the temperature of the buffer plays an important role in ensuring that the temperature does not exceed a set value.9,10 For this reason, the buffer must possess high thermal conductivity to dissipate the heat from the canister.8,9,11,12
STORAGE: A Source Term Model for Intermediate-Level Radioactive Waste
Published in Nuclear Technology, 2022
S. Esnouf, A. Dannoux-Papin, C. Chapuzet, V. Roux-Serret, V. Piovesan, F. Cochin
According to the National Radioactive Waste Management Agency, intermediate-level long-lived waste (ILW-LL) in France represents around 2.9% of the total volume of radioactive waste and contributes around 5% to total radioactivity. The long-term solution for this type of waste is underground disposal in a deep geological repository (CIGEO project).
Microbially influenced corrosion of carbon steel in the presence of anaerobic sulphate-reducing bacteria
Published in Corrosion Engineering, Science and Technology, 2020
Tomáš Černoušek, Rojina Shrestha, Hana Kovářová, Roman Špánek, Alena Ševců, Kristína Sihelská, Jakub Kokinda, Jan Stoulil, Jana Steinová
In the Czech Republic, the general concept of deep geological repository is based on the Swedish KBS-3 concept with certain modifications, for example the repositories are constructed in crystalline host rock using steel-based disposal canisters and bentonite as a buffer material [12], with the metal canisters being embedded several hundred metres below ground level [13]. It has already been demonstrated that microorganisms are present and metabolically active in such deep underground ecosystems [14–17]. The so-called deep biosphere is devoid of oxygen, hence microorganisms use nitrate, manganese, iron, sulphate or carbon dioxide as terminal electron acceptors for respiration, or gain energy through fermentation processes [18]. Sulphate-reducing bacteria (SRB) are typical anaerobes that utilise sulphate as a terminal electron acceptor and organic compounds and hydrogen as electron donors and a source of energy. Under anoxic conditions, which will prevail for most of the repository’s lifetime, SRB gain energy by reduction of sulphate or other sulphur compounds to form hydrogen sulphide (H2S), an aggressive corrosive element that can seriously threaten the integrity of metal canisters by accelerating their corrosion rate [19]. The electron donor is either a hydrogen ion (evolved either as a metabolic product of other bacteria or by hydrolysis due to the corrosion process) or an organic compound [20]. In addition to SRB, other bacterial groups (e.g. thiosulfate-reducing bacteria, nitrate-reducing bacteria, acetogenic bacteria) are also known for their ability to participate in biocorrosion [21–26]. However, SRB are considered to play a key role in the anaerobic corrosion of iron [27–30] as they are widespread in many natural and engineered environments. It has been demonstrated that interface locations between the buffer and other mbkaterials (i.e. at locations constituting a discontinuity in the homogeneity of the buffer) are clearly preferred environments for microbial activity as water content is higher and dry density of the buffer material lower than in the bulk buffer [31]. Since such interfaces will exist between the metal canister and the buffer material, microbial activity is expected to be higher at such locations, possibly resulting in MIC.