Description

The transport of colloids and interaction of contaminants with colloids migrating through the waste package under repository conditions. Colloids are particles with a maximum dimension typically less than 10 μm and are usually considered to have at least one dimension in the range 1 nm to 1 μm. Colloids are particles that can exist within a liquid without settling out.

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.

The potential mobility of radionuclides and other contaminants within a waste package will be influenced by their partitioning between colloids and chemical species in solution, and between colloids and solid phases. Radionuclides or other contaminants may themselves form colloids (e.g. Pu(IV)), be incorporated chemically into the structures of colloids, or may sorb to the surfaces of colloids. In all these cases, the contaminants are transported with the colloids. If the colloids themselves are mobile, then migration of the associated radionuclides or other contaminants will be enhanced. Alternatively, if mobility of the colloids is restricted, for example by filtration as water passes through other materials in the waste package, then migration of the associated radionuclides or other contaminants will be diminished.

2000 List

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

3.2.04

Related References