Description
The hydraulic and hydrogeological characteristics and properties of the geosphere prior to repository construction. Included are characteristics and properties such as the hydraulic conductivity, fracture frequency and connectivity, porosity, tortuosity and pore water pressure of the various rock formations.
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.
Hydraulic characteristics and properties of the geosphere prior to repository construction will influence the subsequent hydrogeological evolution of the geosphere during repository construction, during operation and later, post-closure. These hydraulic characteristics and properties may influence the effectiveness of both the EBS and the geosphere barrier. The rate at which groundwater flows through the EBS will depend partly upon the geosphere’s hydraulic characteristics and properties. This rate of groundwater flow will influence the rate of resaturation of the repository following closure and the rate at which the properties of EBS components evolve (since this evolution depends in part on the supply of solutes and / or water).
The hydraulic characteristics and properties of the geosphere influence the directions and rates of groundwater flow and hence the nature of the pathways for transportation of radionuclides and other contaminants in the aqueous phase in the post-closure period. There may also be an influence on the migration of other fluids (such as non-aqueous liquids and gases), where these are driven by movement of water.
These hydraulic and hydrogeological characteristics and properties may influence the retardation of radionuclides and other contaminants originating in the repository during future transport from the repository through the geosphere. This influence may be direct in the cases of radionuclides and other contaminants that are transported in water. For example, in fractured crystalline rocks, the connectivity between fractures and matrix pores in their walls will influence the retardation by rock matrix diffusion.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.