Description
The migration of reactants into and reaction products from the waste package.
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.
Migration of chemical species to/from the outer surface of a waste package, within a waste package, and to/from its interior (where the package lacks integrity) will influence the pathways by which a package’s components evolve and the rates at which they do so. The presence of certain species, such as chloride, sulphide and sulphate, can promote the corrosion of metals (e.g. high chloride concentrations for steel) and the degradation of cement (high sulphate concentrations). Where a package offers containment initially, the nature of chemical species that migrate to / from the package’s outer surface and the rates at which they do so may determine whether the package loses its containment function within the assessment time frame and if so, when this containment loss occurs. Where a package does not offer containment, the natures of chemical species that migrate into the waste package, and the rates at which they do so, will influence the rates at which radionuclides and other contaminants are released and the chemical forms in which this release occurs. Chemical species that may migrate from such a waste package include chemical species of radionuclides and other contaminants.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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NEA and EC (), Engineered Barrier Systems and the Safety of Deep Geological Repositories, State-of-the-art Report, Nuclear Energy Agency and European Commission, NEA-3615, EUR 19964 EN, https://www.oecd-nea.org/rwm/reports/2003/nea3615-ebs.pdf