Description

The movement of the waste package in the repository. Included are movements from mechanical stresses on the waste package caused by, for example, package deformation or mass redistribution in the repository. Also included are movements resulting from seismic events.

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.

Movement of waste packages could affect the performance and safety of a repository by changing the spatial dispositions of the packages (and hence the wastes), any surrounding engineered barriers, the natural barriers and residual voidage. Potentially a redistribution of waste packages, barriers and voidage could influence the rates at which radionuclides and other contaminants are released from the repository. For example, were a package to move within a surrounding backfill, the thickness of backfill between the package and the rock could be changed; where the thickness is decreased, the backfill would offer less resistance to the migration of radionuclides and other contaminants. Any spatial redistribution of voidage would affect the volume and connectivity of pathways through which groundwater could enter the repository and through which gas, radionuclides and other contaminants could leave the repository. Potentially the movement of waste packages could be short-term (e.g. movement caused by a seismic event) or long-term (e.g. movement caused by rock creep).

2000 List

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

2.1.07

Related References