Description

The physical processes and associated landforms in cold but ice-sheet-free environments within the region/locality of the repository. A key feature of such environments is the formation of large volumes of permanently frozen subsurface soils and rock, called permafrost.

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.

  • Feature
  • 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.

Periglacial effects could impact upon the performance and safety of a repository by: 1) influencing the fluxes and patterns of groundwater flow in and/or around a repository; 2) influencing the chemistry of the groundwater; and 3) influencing the natures and spatial distributions of receptors that could be impacted by any radionuclides or contaminants that are transported from the repository. Frozen ground could restrict groundwater recharge and hence fluxes of groundwater through a repository. The spatial distribution of permafrost could also influence the locations of groundwater recharge and discharge zones. Partial freezing may result in the development of higher salinity residual groundwater. High salinity water may be produced at the base of the permafrost freezing zone. Ground may be locally unfrozen leading to the development of isolated water bodies (taliks) with concentrated contaminant release. Freeze-thaw processes, including frost heave, thermo-karst processes and solifluction may lead to the development of distinctive land-forms. The spatial distribution of permafrost will change to reflect advances and retreats of adjacent glaciers and ice sheets. These processes will cause changes in drainage and watershed systems, which will affect near-surface groundwater flow, and changes in the plant, animal and human communities, which will affect potential exposure pathways.

2000 List

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

1.3.04

Related References