Multiple Roles of Clays in Radioactive Waste Confinement
This Special Publication highlights the importance of clays and clayey material, and their multiple roles, in many national geological disposal facilities for higher activity radioactive wastes. Clays can be both the disposal facility host rock and part of its intrinsic engineered barriers, and may be present in the surrounding geological environment. Clays possess various characteristics that make them high-quality barriers to the migration of radionuclides and chemical contaminants, e.g. very little water movement, diffusive transport, retention capacity, self-sealing capacity, stability over millions of years, homogeneity and lateral continuity.
The 20 papers presented in this Special Publication cover a range of topics related to clays in radioactive waste confinement. Aspects of clay characterization and behaviour at various temporal and spatial scales relevant to the confinement of radionuclides in clay are discussed, from phenomenological processes to the overall understanding of the performance and safety of geological disposal facilities.
A prediction–evaluation approach to the full-scale emplacement experiment (FE) in Mont Terri
Correspondence: [email protected]
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Published:January 01, 2019
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CiteCitation
A. Papafotiou, R. Senger, C. Li, A. Singh, B. Garitte, H. Müller, P. Marschall, 2019. "A prediction–evaluation approach to the full-scale emplacement experiment (FE) in Mont Terri", Multiple Roles of Clays in Radioactive Waste Confinement, S. Norris, E.A.C. Neeft, M. Van Geet
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Abstract
A prediction–evaluation approach is developed to assess the propagation of parameter, conceptual and scenario uncertainties in the estimated near-field temperatures of the full-scale emplacement experiment at the Mont Terri rock laboratory. The uncertainty assessment is performed using a three-dimensional thermo-hydraulic numerical model of the full-scale emplacement experiment that represents the emplaced materials and surrounding Opalinus Clay and accounts for heat generation at the heaters. The propagation of parametric uncertainties is assessed using a first-order second-moment method supplemented by Monte Carlo simulations sampling the uncertain parameter space. The risk of uncertain parameters resulting in the failure of the maximum temperature criteria is evaluated with a first-order reliability method. Conceptual and scenario uncertainties are evaluated with deterministic simulation variants. After the conclusion of predictive modelling, a mid-term evaluation of the temperature predictions is performed through a comparison with measurements after 2.5 years of heating. The comparison indicates that the best estimates of temperature agree well with the measurements and that the 95% error bands assessed with parametric uncertainty envelope the measured values in almost all locations. Additional comparison with the measured degree of water saturation and the relative humidity is performed to assess the hydraulic behaviour and set the ground for the long-term evaluation, which will include predictions of the near-field pore pressures.
- bedding
- behavior
- bentonite
- calibration
- Central Europe
- clastic rocks
- compressibility
- computer programs
- disposal barriers
- equations
- errors
- Europe
- evaluation
- excavations
- expansive materials
- experimental studies
- geometry
- heat capacity
- heat flow
- Jurassic
- materials
- measurement
- Mesozoic
- models
- Monte Carlo analysis
- numerical models
- Opalinus Clay
- permeability
- planar bedding structures
- pore pressure
- porosity
- prediction
- pressure
- properties
- radioactive waste
- saturation
- sedimentary rocks
- sedimentary structures
- simulation
- statistical analysis
- Switzerland
- temperature
- thermal conductivity
- three-dimensional models
- TOUGH2
- waste disposal
- relative humidity
- Mont Terri Rock Laboratory