Description
The deformation of the waste package due to large loads and pressures imposed on it from both internal and external sources.
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.
Deformation of a waste package, whether generated by internal or external processes, if of sufficient magnitude, could affect the integrity of the package. A package that initially contains openings (e.g. a vented container) may have larger openings produced within it. A package that initially offers complete containment may lose its integrity. If the deformation affects a package that does not offer containment, then it could produce fracture pathways for the migration of radionuclides and other contaminants from the package. Deformation may also lead to the decreases in the volume of any voids present and the development of pressure gradients. These processes could promote the migration of radionuclides and other contaminants from the waste package. Deformation of a waste package may also influence the performance of engineered and natural barriers that surround the package. For example, a volume reduction of the package could potentially allow cracking of any surrounding cementitious backfill that might be present. Deformation may occur over time periods that are very short compared to the assessment period (e.g. shearing due to fracture movement during a seismic event) or over longer time periods (e.g. loading by creep of the surrounding geosphere).
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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Frost H J and Ashby M F (), Deformation Mechanisms Maps – The plasticity and creep of metals and ceramics, Pergamon Press (Oxford, New York), http://engineering.dartmouth.edu/defmech/
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Sandström R (), Basic model for primary and secondary creep in copper, Acta Materialia, Elsevier, 60, 314-322