Bentonite colloid diffusion through the host rock of a deep geological repository

2007 ◽  
Vol 32 (1-7) ◽  
pp. 469-476 ◽  
Author(s):  
U. Alonso ◽  
T. Missana ◽  
A. Patelli ◽  
V. Rigato
Keyword(s):  
Host Rock ◽  
Deep Geological Repository ◽  
Geological Repository ◽  
Bentonite Colloid

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 Lifetimes of Used Nuclear Fuel Containers Affected by Sulphate-Reducing Bacteria Reactions inside the Canadian Deep Geological Repository

2021 ◽  
Vol 11 (17) ◽  
pp. 7806
Author(s):  
Jorge A. Garcia-Hernandez ◽  
Kumaraswamy Ponnambalam ◽  
Mythreyi Sivaraman
Keyword(s):  
Nuclear Fuel ◽  
Host Rock ◽  
Bentonite Clay ◽  
Reaction Diffusion ◽  
Deep Geological Repository ◽  
Sulphate Reducing Bacteria ◽  
Used Nuclear Fuel ◽  
Geological Repository ◽  
Sulphide Production ◽  
Reducing Bacteria

The present work aims at approximating the reduction of sulphate to sulphide caused by sulphate-reducing bacteria (SRB) inside the Canadian deep geological repository in order to calculate the expected lifetime of used nuclear fuel containers (UFCs). Previous studies have assumed a conservative constant concentration of sulphide at the host rock interface. The novelty of this study resides in the use of first-order kinetics to explicitly account for the SRB-induced sulphide production. This reaction term is developed following an empirical approach using published results on actual sulphate reduction by SRB and included in a coupled reaction-diffusion system. Lifetimes of UFCs are subsequently calculated following the conditions of two scenarios: having SRB active only at the region closest to the host rock and having SRB active at the host rock and throughout the bentonite clay. This study shows that the mean lifetimes of UFCs in both cases are above one million years. However, more accurate results would require the characterization of the host rock and groundwater of the prospective emplacement, as well as additional experiments on growth and sulphide production by the microbial communities from the site.

Project Opalinus Clay – Geoscientific Basis for the Demonstration of Feasibility of Disposal (Entsorgungsnachweis) for SF, Vitrified HLW and Long-Lived ILW in Switzerland

2003 ◽  
Vol 807 ◽  
Author(s):  
A. Gautschi ◽  
A. Lambert ◽  
P. Zuidema
Keyword(s):  
Radioactive Waste ◽  
Host Rock ◽  
Opalinus Clay ◽  
Geological Environment ◽  
Deep Geological Repository ◽  
Geological Repository ◽  
National Cooperative

ABSTRACTNagra - the Swiss National Cooperative for the Disposal of Radioactive Waste - has completed a study to determine the suitability of Opalinus Clay as a host rock for a SF/HLW/ILW repository in a potential siting area (reference repository site) in the Zürcher Weinland in northeastern Switzerland. Geoscientific information has been used to a wide extent for the demonstration of siting and engineering feasibility, and for the demonstration of long-term safety. It is shown that the selected area in the Zürcher Weinland fulfils the fundamental requirements placed on a siting area for a deep geological repository and that, in terms of the Opalinus Clay host rock option, the geological environment is advantageous.

Evaluation of Limiting Nutrients in a Deep Geological Repository

2016 ◽  
Author(s):  
Scott Briggs ◽  
Brent Sleep ◽  
Jennifer McKelvie ◽  
Magdalena Krol
Keyword(s):  
Deep Geological Repository ◽  
Geological Repository ◽  
Limiting Nutrients

A Numerical Simulation of Diffusion Experiment in Clay

2011 ◽  
Vol 322 ◽  
pp. 353-356
Author(s):  
Qing Chun Yang
Keyword(s):  
Numerical Simulation ◽  
Opalinus Clay ◽  
Isotropic Case ◽  
Diffusion Experiment ◽  
Deep Geological Repository ◽  
Transport Distance ◽  
Geological Repository ◽  
Geological Formation ◽  
Clay Formation ◽  
Anisotropic Case

Safety assessment of nuclear waste disposal in a deep geological repository requires understanding and quantifying radionuclide transport through the hosting geological formation. Determining diffusion parameters under real conditions is necessary for the performance assessment of a deep geological repository where high level wastes are placed for safety disposal. The in situ diffusion and retention (DR) experiments are designed to study the transport and retention properties of the Opalinus clay formation. In this paper, a scoping numerical simulation is performed in Opalinus Clay, The simulated results for all the traces illustrate that the maximum transport distance perpendicular to the bedding is larger in the isotropic case and those along the bedding is larger in the anisotropic case. Tracer depletion in the isotropic case is a little larger than in the anisotropic case. Deuterium and iodide can be detected in the other interval but strontium can’t. Since the length of injection interval is shorter than the transport distance, the anisotropy effect is clearly measurable. This numerical simulation of diffusion experiment aims at contributing to the optimum design of the experiment. The results of this experiment will provide additional insight into the role of diffusion anisotropy and sorption parameters for radionuclides in clays.

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