Description
The dilation of repository materials due to gas pressure.
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.
- Event
- Process
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.
Dilation of materials in the EBS and / or the host rock immediately surrounding the repository, caused by gas pressures generated within the repository, may damage the EBS and/or natural barriers. Dilation may produce new microscopic or macroscopic pathways through the engineered or natural barriers or increase the apertures of existing pathways. Via these pathways, gas will migrate and may carry radionuclides and other contaminants with it. Depending upon the mechanical properties of the engineered and natural barriers, and the prevalent stress regime, the pathways may close if gas pressures dissipate, or they may remain open. If pathways remain open, they might subsequently conduct groundwater or non-aqueous fluids that could transport radionuclides and other contaminants, should these be released from waste packages.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.