Description

The migration of contaminants in solid phase in the geosphere.

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.

Solid-mediated migration may influence the rates at which radionuclides and other contaminants are transported through the geosphere from a repository (if there are pathways through the EBS) and the pathways followed. Such transport implies the existence of a sufficient driving force and that pathways are sufficiently large that solid particles can move through them.

Solid-mediated migration might affect the dispersion of radionuclides and other contaminants. This influence will reflect the fact that different solid materials may form particles of different shapes and sizes while at the same time potentially transporting different contaminants. For example, some radionuclides may have a relatively great tendency to be incorporated into the structures of solid carbonate phases, whereas other radionuclides may have a relatively great tendency to sorb onto clay minerals. Solid carbonate particles and clay particles may show different transport behaviours.

Radionuclides and other contaminants may partition between moving solid phases and other phases that are present. This partitioning will be affected by the pressure and temperature and chemical environment within which transport occurs.

2000 List

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

3.2.08