Description

The characteristics of the atmosphere, including capacity for transport of contaminants, and the processes affecting their potential evolution.

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

Comments

The “Comments” field, when present, contains any additional explanation of the IFEP, beyond that implicit in the FEP's description and provided in the “Relevance to Performance and Safety” field. This additional explanation may include, where appropriate, the IFEPs characteristics, the circumstances under which it might be relevant and its relationship to other (especially similar) IFEPs.

The atmosphere may be divided into a near-surface layer, in which contaminants are subject to uptake by plants, and the wider atmosphere above the surface environment.

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.

Contaminants migrating from the repository may enter the atmosphere either in gaseous form, or in particulate form as a result of resuspension.

Within the atmosphere there are several physical processes – transport of gases, aerosols and dust – as well as chemical and photochemical reactions, which will affect the concentration of contaminants in the atmosphere that humans and non-human biota are exposed to.

All potential human activities, both indoors and outdoors, may give rise to exposures due to atmospheric concentrations of contaminants. These activities include inhalation of radioactive vapours as well as airborne particulates, external immersion, and the ingestion of deposited material also forms a potential exposure route.

2000 List

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

2.3.07

Related References