Description
The mechanical characteristics and properties of the geosphere prior to repository construction. Included are properties such as the stress regime and compressive and shear strength 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.
Mechanical characteristics and properties of the prior to repository construction will influence the subsequent mechanical evolution of the geosphere during repository construction, during operation, and later, post-closure. These mechanical characteristics and properties may influence the effectiveness of both the engineered barrier system (EBS) and the geosphere barrier. The stress regime and mechanical characteristics (including, among others, uniaxial compressive strength, tensile strength, shear strength, Young’s Modulus, Poisson’s ratio and the anisotropy of these parameters) of the geosphere will influence the design of the repository and the ease with which it can be constructed. In the operational period, these characteristics and properties will influence the evolution of void spaces and the measures that need to be taken to ensure a safe environment within which wastes and EBS components can be emplaced. They also determine the evolution of the EDZ over time. In the post-closure period, mechanical characteristics and properties of the geosphere will influence the rate at which residual porosity in the repository is lost and the stresses on EBS components and waste containers. These factors will influence in turn whether the canisters and EBS components fail and the timing of any such failure that occurs. The mechanical characteristics and properties of the geosphere will affect the responses of the geosphere to loading (e.g. by ice sheets) and unloading (e.g. by uplift accompanied by erosion) and tectonic movements, including those due to earthquakes. These responses may include the development of forces driving the migration of fluids (such as water, non-aqueous liquids or gases) from the repository, and the development of migration pathways for these fluids and any radionuclides or other contaminants originating in the repository that these fluids may carry.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.