scholarly journals Thermally Constrained Conceptual Deep Geological Repository Design under Spacing and Placing Uncertainties

2021 ◽  
Vol 11 (24) ◽  
pp. 11874
Author(s):  
Jeremy Leong ◽  
Kumaraswamy Ponnambalam ◽  
Jeff Binns ◽  
Ali Elkamel
Keyword(s):  
Design Process ◽  
Crystalline Rock ◽  
Temperature Tolerance ◽  
Temperature Evolution ◽  
Maximum Temperature ◽  
Deep Geological Repository ◽  
High Temperature Tolerance ◽  
Geological Repository ◽  
Permanent Storage ◽  
High Level

The temperature evolution within a deep geological repository (DGR) is a key design consideration for the safe and permanent storage of the high-level radioactive waste contained inside used nuclear fuel containers (UFCs). Due to the material limitations of engineered components with respect to high temperature tolerance, the Nuclear Waste Management Organization of Canada requires the maximum temperature within a future Canadian DGR to be less than 100 °C. Densely placing UFCs within a DGR is economically ideal, but greater UFC placement density will increase the maximum temperature reached in the repository. This paper was aimed to optimize (i) the separation between UFCs, (ii) the distance between container placement rooms, and (iii) the locations of the age-dependent UFCs in the placement rooms for a conceptual DGR constructed in crystalline rock. Surrogate-based optimization reduced the amount of computationally expensive evaluations of a COMSOL Multiphysics model used to study the temperature evolution within the conceptual DGR and determined optimal repository design points. Via yield optimization, nominal design points that considered uncertainties in the design process were observed. As more information becomes available during the design process for the Canadian DGR, the methods employed in this paper can be revisited to aid in selecting a UFC placement plan and to mitigate risks that may cause repository failure.

scholarly journals State-of-the-art and proof-of-concept installations for repository concepts based in crystalline rock

2015 ◽  
Vol 79 (6) ◽  
pp. 1665-1673 ◽  
Author(s):  
Magnus Kronberg ◽  
Jan Gugala ◽  
Keijo Haapala
Keyword(s):  
Laser Scanning ◽  
Crystalline Rock ◽  
High Level Waste ◽  
Geological Disposal ◽  
Geological Repository ◽  
Reference Design ◽  
Potential Alternative ◽  
Deep Underground ◽  
High Level

AbstractOver the last five decades private and national energy programmes worldwide have been producing a variety of radioactive wastes. One of the safest ways of disposing of this waste is to bury it deep underground in purpose-built geological disposal facilities. Currently, there is no operating geological repository in Europe for high-level waste but the goal of the IGD-TP is that the first repository shall be fully operational before the year 2025. Several studies and experiments are ongoing at various potential repository sites in Europe with the goal to establish general approaches that can be adapted for any country in need of a geological repository.The Swedish Nuclear Fuel and Waste Management Co (SKB) in Sweden and Posiva Oy in Finland are developing a method for geological disposal of high-level long-lived nuclear waste in crystalline rock, the KBS-3 method. KBS-3V (vertical) is both organizations reference design, but KBS-3H (horizontal) emplacement is also being researched as a potential alternative. Of high importance in the development is demonstrating the technical feasibilityin situof safe and reliable construction, manufacturing, disposal and sealing of such geological disposal facilities. Parts of these demonstrations are carried out under the framework of EurAtom/FP7 and one of these projects is the LUCOEX project where SKB is demonstrating horizontal emplacement, the Multi Purpose Test (MPT), and Posiva is demonstrating vertical buffer installation processes.The MPT includes the key components of the horizontal design and comprises all essential steps; manufacturing of the full-scale components, their assembly, installation in the drift and monitoring of the early buffer evolution. The MPT installation was successfully performed in late 2013. By combining the components, an initial verification of the design implementation has been achieved. At the same time, integrating the components has meant the recognition of some design weaknesses and the design will be updated accordingly.Posiva's KBS-3V buffer installation equipment that places buffer blocks with high precision in vertical deposition holes is currently being developed and will be tested during 2014 and 2015 in real underground conditions. The machine uses vacuum lifting tools for moving the buffer blocks and laser scanning technology to position both the machine and blocks. Functionality of the concept and equipment selected will be confirmed by the tests and the installation tests will provide important information about the suitability of the selected buffer dimensions and tolerances.

Investigation on Suitability of Argillaceous Rocks of Vindhyan Super Group as Host Rock for Deep Geological Repository using Thermal Analysis

2021 ◽  
Vol 38 (1) ◽  
pp. 119-125
Author(s):  
T.K. Pal ◽  
R.K. Bajpai ◽  
A. Acharya ◽  
R. S. Bhatia ◽  
D. Datta
Keyword(s):  
Host Rock ◽  
Near Field ◽  
Permissible Limit ◽  
Heat Diffusion ◽  
Maximum Temperature ◽  
Model Parameters ◽  
Deep Geological Repository ◽  
Vindhyan Super Group ◽  
Argillaceous Rocks ◽  
Geological Repository

Argillaceous rocks are being considered as a potential host rock for deep geological repository (DGR) for hosting vitrified high level radioactive waste canisters by many countries worldwide. Numerical simulation of thermal evolution in the repository environment is an important study for the long term safety performance assessment of a DGR. In this study, thermal dissipation in the near field area of a conceptual repository in Ganurgarh shales from Bhander Group of Vindhyan Super Group, which is the thickest sedimentary succession of India,  has been simulated using commercial software FLAC3D, which solves the governing heat diffusion equation using explicit and implicit finite difference methods. Model parameters like thermal conductivity, specific heat, density of the shales are generated in the laboratory.  From the analysis of time dependent temperature profile it is observed that maximum temperature of 70.5oC is attained at canister surface after 22 years of heating for a heat loadings of 500 W/overpack. Since the maximum temperature is well below the permissible limit of temperature (100oC), the heat load of the source is increased to 700 W/overpack and in this case the simulated value of maximum temperature is 93­oC.  Maximum temperatures at other locations within the near field region are also within the permissible limit.

scholarly journals Microbiology of Barrier Component Analogues of a Deep Geological Repository

2021 ◽  
Author(s):  
Rachel C Beaver ◽  
Katja Engel ◽  
W. Jeffrey Binns ◽  
Josh Neufeld
Keyword(s):  
Nuclear Fuel ◽  
Selection Process ◽  
Crystalline Rock ◽  
Opalinus Clay ◽  
Rrna Gene ◽  
Deep Geological Repository ◽  
Used Nuclear Fuel ◽  
Geological Repository ◽  
Clay Formation

Canada is currently implementing a site selection process to identify a location for a deep geological repository (DGR) for the long-term storage of Canada’s used nuclear fuel, wherein used nuclear fuel bundles will be sealed inside copper-coated carbon steel containers, encased in highly compacted bentonite clay buffer boxes and sealed deep underground in a stable geosphere. Because a DGR must remain functional for a million years, there is value to examining ancient natural systems that serve as analogues for planned DGR components. Specifically, studying the microbiology of natural analogue components of a DGR is important for developing an understanding of the types of microorganisms that may be able to grow and influence the long-term stability of a DGR. This study explored the abundance, viability, and composition of microorganisms in several ancient natural analogues using a combination of cultivation and cultivation-independent approaches. Samples were obtained from the Tsukinuno bentonite deposit (Japan) that formed ~10 mya, the Opalinus Clay formation (Switzerland) that formed ~174 mya, and Canadian shield crystalline rock from Northern Ontario that formed ~2.7 bya. Analysis of 16S rRNA gene amplicons revealed that three of the ten Tsukinuno bentonite samples analyzed were dominated by putative aerobic heterotrophs and fermenting bacteria from the Actinobacteria phylum, whereas five of the Tsukinuno bentonite samples were dominated by sequences associated with putative acidophilic chemolithoautotrophs capable of sulfur reduction.

Laboratory and Modelling Studies of Microbial Activity in the Near Field of a HLW Repository

1985 ◽  
Vol 50 ◽  
Author(s):  
Julia M West ◽  
Ian G McKinley ◽  
Helen A Grogan ◽  
Susan C Arme
Keyword(s):  
Recent Literature ◽  
Near Field ◽  
Deep Geological Repository ◽  
Sampling Studies ◽  
Geological Repository ◽  
Modelling Studies ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Hlw Repository ◽  
Microbial Effects

Microbial effects are one of the possible perturbations to the expect-ed performance of a deep geological repository which must be examined as part of a comprehensive safety analysis. Recent literature surveys (eg [1, 2] ) and reconnaisance sampling studies [3, 4] have concluded that: a) microbial contamination of a repository is inevitable b) even for high level nuclear waste, conditions in the near-field are insufficiently extreme to ensure complete sterilisation.

scholarly journals Needs of countries with longer timescale for deep geological repository implementation

2020 ◽  
Vol 6 ◽  
pp. 22
Author(s):  
Bálint Nős
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
High Level Waste ◽  
Deep Geological Repository ◽  
Spent Fuel ◽  
International Consensus ◽  
Geological Disposal ◽  
Geological Repository ◽  
Deep Geological Disposal ◽  
High Level

Countries operating nuclear power plants have to deal with the tasks connected to spent fuel and high-level radioactive waste management. There is international consensus that, at this time, deep geological disposal represents the safest and most sustainable option as the end point of the management of high-level waste and spent fuel considered as waste. There are countries with longer timescale for deep geological repository (DGR) implementation, meaning that the planned date of commissioning of their respective DGRs is around 2060. For these countries cooperation, knowledge transfer, participation in RD&D programmes (like EURAD) and adaptation of good international practice could help in implementing their own programmes. In the paper the challenges and needs of a country with longer implementation timescale for DGR will be introduced through the example of Hungary.

scholarly journals Genetic contribution to high temperature tolerance in Cryptococcus neoformans

Genetics ◽  
2020 ◽  
Vol 217 (1) ◽  
Author(s):  
Piotr R Stempinski ◽  
Jessica M Zielinski ◽  
Nadir H Dbouk ◽  
Elizabeth S Huey ◽  
Ellen C McCormack ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Cryptococcus Neoformans ◽  
Temperature Tolerance ◽  
Maximum Temperature ◽  
Synthetic Lethal ◽  
High Temperature Tolerance ◽  
Free Media ◽  
Complex Signaling ◽  
Genetic Contributions

Abstract The human fungal pathogen Cryptococcus neoformans relies on a complex signaling network for the adaptation and survival at the host temperature. Protein phosphatase calcineurin is central to proliferation at 37°C but its exact contributions remain ill-defined. To better define genetic contributions to the C. neoformans temperature tolerance, 4031 gene knockouts were screened for genes essential at 37°C and under conditions that keep calcineurin inactive. Identified 83 candidate strains, potentially sensitive to 37°C, were subsequently subject to technologically simple yet robust assay, in which cells are exposed to a temperature gradient. This has resulted in identification of 46 genes contributing to the maximum temperature at which C. neoformans can proliferate (Tmax). The 46 mutants, characterized by a range of Tmax on drug-free media, were further assessed for Tmax under conditions that inhibit calcineurin, which led to identification of several previously uncharacterized knockouts exhibiting synthetic interaction with the inhibition of calcineurin. A mutant that lacked septin Cdc11 was among those with the lowest Tmax and failed to proliferate in the absence of calcineurin activity. To further define connections with calcineurin and the role for septins in high temperature growth, the 46 mutants were tested for cell morphology at 37°C and growth in the presence of agents disrupting cell wall and cell membrane. Mutants sensitive to calcineurin inhibition were tested for synthetic lethal interaction with deletion of the septin-encoding CDC12 and the localization of the septin Cdc3-mCherry. The analysis described here pointed to previously uncharacterized genes that were missed in standard growth assays indicating that the temperature gradient assay is a valuable complementary tool for elucidating the genetic basis of temperature range at which microorganisms proliferate.

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