Description

The migration of dissolved contaminants by the bulk flow of the water through 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.

The bulk movement of liquid through a waste package has the potential to transport radionuclides and other contaminants from the waste form itself to the inner surfaces of the container. This bulk movement of liquid will influence the degree to which concentrations of radionuclides or other contaminants present in the liquid are homogenised. Under liquid-saturated conditions, the more rapid the advection the more rapidly will concentrations of radionuclides or other contaminants homogenise. Under partially liquid-saturated conditions advection of a liquid phase will tend to transport radionuclides and other contaminants downwards within the waste package. If more than one immiscible liquid phase occurs, then the phases may move relative to one another under the influence of buoyancy. In such a case, partitioning of radionuclides or other contaminants between the liquid phases may cause contaminant concentrations to vary spatially within the waste package. If advection produces spatially heterogeneous concentrations of radionuclides or other contaminants within the waste package, the rates at which contaminants are released from a vented or breached waste package will depend upon the location of the vent or breach.

2000 List

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

3.2.07

Related References