Description

The migration of contaminants from the geosphere as a direct result of human actions.

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.

Human actions may lead to radionuclides and other contaminants being transported from the repository and / or from its surrounding geosphere (should the EBS have pathways through which contaminants leave the repository). The nature of the human actions will determine the pathways via which the radionuclides and other contaminants are transported, the rates at which this transport occurs, and the physico-chemical forms in which it occurs. For example, drilling a single exploratory borehole into a repository might transport radionuclides and other contaminants to the surface in a variety of phases (possibly a combination of solids, liquid water, non-aqueous liquids and gases). However, this transport is likely to be very localised (to the borehole and its immediate surroundings at the surface). In contrast, should the EBS have pathways through which radionuclides and other contaminants leave the repository, subsequent large-scale groundwater abstraction from multiple wells drilled near the repository, but to shallower depths, might transport predominantly contaminated groundwater to the surface over a relatively wide area.

Human actions might result in changes to the partitioning of radionuclides and other contaminants among mobile and immobile phases, which might impact upon contaminant transport. For example, depressurisation of groundwater during sampling from a borehole might cause dissolved CO₂ to exsolve, with consequent partitioning of C-14 from aqueous carbonate to gaseous CO₂.

2000 List

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

3.2.12