Description

The migration of contaminants in solid phase from the repository.

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

Comments

The “Comments” field, when present, contains any additional explanation of the IFEP, beyond that implicit in the FEP's description and provided in the “Relevance to Performance and Safety” field. This additional explanation may include, where appropriate, the IFEPs characteristics, the circumstances under which it might be relevant and its relationship to other (especially similar) IFEPs.

This might result from processes such as the fluvial erosion of the repository (FEP 1.2.8), the glacial erosion of the repository (FEP 1.3.5) or magmatic/volcanic activity affecting the repository (FEP 1.2.5).

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.

The pathways by which radionuclides and other contaminants might leave the repository, the fluxes attained, and their bioavailability could be influenced by solid-mediated transport. The solids may be particles of waste, if the waste packages are physically compromised. Alternatively, the solids may be particles of engineered barrier components that have previously been contaminated, for example by radionuclides and other contaminants that have been transported into the EBS by water or gas (assuming that this transport from a waste package is possible).

Solid-mediated transport may occur in concert with some other transport mechanism. For example, small contaminated solid particles may be transported as dust within moving air, in the operational phase of a repository, or if the repository is exposed to the air in the post-closure period by uplift and erosion. Another example would be transport of contaminated solid particles from the repository to the surface as chippings in drilling fluids, should humans drill into the repository in future.

2000 List

A reference to the related FEP(s) within the 2000 NEA IFEP List.

3.2.08

Related References