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.

A Comparative Study on Scoping Numerical Calculations of Anisotropic Diffusion Experiment in Clay

2011 ◽  
Vol 148-149 ◽  
pp. 1434-1437
Author(s):  
Qing Chun Yang
Keyword(s):  
Distribution Coefficients ◽  
Diffusion Experiment ◽  
Deep Geological Repository ◽  
Transport Distance ◽  
Diffusion Parameters ◽  
Anisotropy Effect ◽  
Geological Repository ◽  
Final Design ◽  
Geological Formation ◽  
Injection Interval

Safety assessment of nuclear waste disposal in a deep geological repository requires understanding and quantifying radionuclide transport through the hosting geological formation. Radionuclide diffusion is the main transport mechanism in clay formations since they usually have small hydraulic conductivities. Thus, understanding diffusion and determining diffusion parameters under real conditions is crucial for the performance assessment of a deep geological repository. In this paper, a comparative analysis is performed which focus on the dimensions of the packed-off section where tracers are injected and the packer between the intervals, diffusion of neutral (HTO), anionic (I) and sorbing cationic tracers with different distribution coefficients (22Na and 85Sr) has been simulated considering the anisotropy effect. The results indicate that The expected anisotropy has been clearly measurable for the sake of a short injection interval, in the final geometric configuration, the length of injection interval is larger than the transport distance, so the anisotropy effect is not as clearly measurable as in the preliminary because practically no tracer breakthrough from one interval to the other is expected if diffusion anisotropy is confirmed. The tracer depletion in the final design is larger than in the preliminary design.

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.

A fully 3-D anisotropic numerical model of the DI-B in situ diffusion experiment in the Opalinus clay formation

2006 ◽  
Vol 31 (10-14) ◽  
pp. 531-540 ◽  
Author(s):  
J. Samper ◽  
C. Yang ◽  
A. Naves ◽  
A. Yllera ◽  
A. Hernández ◽  
...  
Keyword(s):  
Numerical Model ◽  
Opalinus Clay ◽  
Diffusion Experiment ◽  
In Situ Diffusion ◽  
Clay Formation

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.

The Swiss Strategy for HLW Siting; Parallel Investigation of two Alternative Host Rocks

1994 ◽  
Vol 353 ◽  
Author(s):  
C. McCombie ◽  
I.G. McKinley ◽  
A. Lambert ◽  
M. Thury ◽  
P. Birkhäuser
Keyword(s):  
Opalinus Clay ◽  
Current Status ◽  
Alternative Host ◽  
Deep Geological Repository ◽  
Northern Switzerland ◽  
Geological Repository ◽  
Site Characterisation ◽  
Host Rocks ◽  
Year 2000 ◽  
Hlw Repository

AbstractRegional characterisation studies of two potential host rocks for a HLW repository - the crystalline basement and the Opalinus clay of Northern Switzerland - have now been completed and documented. Application is now proceeding for the legally required federal, cantonal and communal drilling permits to initiate parallel local investigations in both these formations. The decision to continue with work in both formations is a departure from previously published plans which is intended to maximise the probability that the next major milestone in the HLW programme - demonstrating the feasibility of siting for a deep geological repository in Switzerland - can be reached by the year 2000. This paper reviews the current status of the Swiss HLW programme and outlines the planned “Phase II” site characterisation of the two chosen sites.

DI-B experiment: planning, design and performance of an in situ diffusion experiment in the Opalinus Clay formation

2004 ◽  
Vol 26 (1-4) ◽  
pp. 181-196 ◽  
Author(s):  
A. Yllera ◽  
A. Hernández ◽  
M. Mingarro ◽  
A. Quejido ◽  
L.A. Sedano ◽  
...  
Keyword(s):  
Opalinus Clay ◽  
Experiment Planning ◽  
Diffusion Experiment ◽  
In Situ Diffusion ◽  
And Performance ◽  
Clay Formation

Results of a Recent Safety Assessment of a Proposed Deep Geological Repository in the Opalinus Clay of the Zu¨rcher Weinland in Northern Switzerland

2003 ◽  
Author(s):  
J. W. Schneider ◽  
L. H. Johnson ◽  
P. Zuidema ◽  
P. Gribi ◽  
G. Mayer ◽  
...  
Keyword(s):  
Safety Assessment ◽  
Opalinus Clay ◽  
High Level Waste ◽  
Deep Geological Repository ◽  
Spent Fuel ◽  
Actual Performance ◽  
Northern Switzerland ◽  
Low Concentrations ◽  
Geological Repository ◽  
High Level

A safety assessment of a proposed deep geological repository for the direct disposal of spent UO2 or mixed-oxide fuel, vitrified high-level waste from the reprocessing of spent fuel and long-lived intermediate-level waste in the Opalinus Clay of the Zu¨rcher Weinland of northern Switzerland is described. The assessment methodology is systematic and transparent, and includes the analysis of a broad range of assessment cases, as well as complementary analyses and the formulation of more qualitative arguments. Analyses show compliance with Swiss regulatory Protection Objectives in all cases, and safety indicators complementary to dose and risk further illustrate the low concentrations and fluxes of radioactivity that are expected. No outstanding issues are identified with the potential to compromise safety. The existence of phenomena that are beneficial to safety, but are deliberately (and conservatively) excluded from the assessment (reserve FEPs) indicates that the actual performance of the repository will be even more favourable than the results of the analyses suggest.

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