Description
The succession and spatial extent of the rocks that form the geosphere. Typically rocks are divided into specified rock formations with similar properties and characteristics. These various geological formations help to isolate the repository from the surface environment. Consideration needs to be given to the vertical thickness and horizontal extent of each rock formation.
Category
Categorisation as a Feature, Event and/or Process.
Features
are physical components of the disposal system and environment being assessed. Examples include waste packaging, backfill, surface soils. Features typically interact with one another via processes and in some cases events.Events
are dynamic interactions among features that occur over time periods that are short compared to the safety assessment timeframe such as a gas explosion or meteorite impact.- "Processes" are issues or dynamic interactions among features that generally occur over a significant proportion of the safety assessment timeframe and may occur over the whole of this timeframe. Events and processes may be coupled to one another (i.e. may influence one another).
The classification of a FEP as an event or process depends upon the assessment context, because the classification is undertaken with reference to an assessment timeframe. In this generic IFEP List, many IFEPs are classified as both Events and Processes; users will need to decide which of these classifications is relevant to their context and its timeframes.
- Feature
Relevance to Performance and Safety
The “Relevance to Performance and Safety” field contains an explanation of how the IFEP might influence the performance and safety of the disposal system under consideration through its impact on the evolution of the repository system and on the release, migration and/or uptake of repository-derived contaminants.
The succession and spatial extent of the rocks that form the geosphere will influence the geometry of any repository (e.g. the size of the repository may be limited by the vertical or lateral dimensions of the host rock formation), including access tunnels. There will also be an influence on the overall geomechanical properties of the geosphere and on whether deformation during the operational phase may cause or influence pathways for the transport of water, gas, radionuclides and other contaminants during the post-closure phase.
The permeability / hydraulic conductivity distribution of the geosphere around the repository will also depend upon the succession and spatial extent of the surrounding rocks. There will be consequent effects on groundwater flows towards the repository during the operational phase, and on resaturation of the repository during the post-closure phase in those lithologies that have connected water capable of flowing.
In the post-closure phase, the succession and spatial extent of the rocks around the repository will influence the geometries and transport / retardation characteristics of pathways through the geosphere, between the repository and the biosphere, through which there is flow of fluid (such as water, non-aqueous liquids or gases) and consequent transport of radionuclides may occur.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
-
Murphy MA and Salvador A (), International Subcommission on Stratigraphic Classification of IUGS International Commission on Stratigraphy International Stratigraphic Guide —An abridged version, Episodes, International Union of Geosciences, 22, 255-272, http://www.episodes.org/journalArchiveArticle.do
-
Fossen H (), Structural Geology, Structural Geology, Cambridge University Press, 524, http://www.cambridge.org/gb/academic/subjects/earth-and-environmental-science/structural-geology-tectonics-and-geodynamics/structural-geology-2nd-edition?format=HB#AFepMRSRKjkUBrIV.97
-
Le Maitre RW (editor) (), Igneous Rocks: A Classification and Glossary of Terms, Recommendations of the International Union of Geological Sciences, Subcommission of the Systematics of Igneous Rocks, Cambridge University Press, 205, http://www.cambridge.org/gb/academic/subjects/earth-and-environmental-science/mineralogy-petrology-and-volcanology/igneous-rocks-classification-and-glossary-terms-recommendations-international-union-geological-sciences-subcommission-systematics-igneous-rocks-2nd-edition?format=PB#eTbyCFk3VEMy8WJO.97