Multiple Roles of Clays in Radioactive Waste Confinement
CONTAINS OPEN ACCESS

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.
New results of Boda Claystone research: Genesis, mineralogy, geochemistry, petrophysics
Correspondence: fedor.ferenc@geochem-ltd.eu
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Published:January 01, 2019
Abstract
Boda Claystone is a very tight clayey rock with extreme low porosity and permeability, nano-size pores and small amounts of swelling clays. Due to this character it is ideal as a potential host rock for research into the possibilities of high-level waste deposition in geological formation. Though the research started more than 30 years ago, the genesis, the geotectonic history of the Boda Claystone Formation (BCF) and the geology of surrounding areas has only been sketched out recently. On the basis of research of the past few years the process of sedimentation of different blocks was able to be reconstructed. Equipment and methodological developments were needed for the investigation of reservoir geological and hydrodynamic behaviour of this rock, which began in the early 2000s. Based on them the pore structure and reservoir could be characterized in detail. Only theoretical approaches were available for the chemical composition of free porewater. Traditional water-extracting methods were not adaptable because of excessively low porosity and nano-scale pore size distribution. Hence, new ways have to be found for getting enough water for analysis. These new results of BCF research help to prepare more sophisticated and directed experiments, in which there is a great interest internationally.
- adsorption
- behavior
- body waves
- boreholes
- Central Europe
- characterization
- chemical composition
- chlorite
- chlorite group
- clastic rocks
- claystone
- cores
- crystallinity
- desorption
- diagenesis
- elastic waves
- Europe
- expansive materials
- experimental studies
- genesis
- geochemistry
- high-level waste
- host rocks
- Hungary
- hydrochemistry
- illite
- in situ
- isotherms
- laboratory studies
- late diagenesis
- lithostratigraphy
- measurement
- Mecsek Mountains
- mineral composition
- outcrops
- P-waves
- Paleozoic
- Pannonian Basin
- permeability
- Permian
- physical properties
- pore water
- porosity
- pressure
- radioactive waste
- reconstruction
- reservoir properties
- sample preparation
- sampling
- sedimentary rocks
- sedimentation
- seismic waves
- sheet silicates
- silicates
- solute transport
- temperature
- textures
- thickness
- Transdanubia
- transport
- Upper Permian
- velocity
- vitrinite reflectance
- waste disposal
- well logs
- southwestern Hungary
- Gorica Block
- Boda Claystone Formation
- Boda Block