Description
The migration of any repository-derived contaminants in gas or vapour phase or as fine particulate or aerosol in gas or vapour through the biosphere.
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.
- 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.
Repository-derived contaminants may enter the atmosphere as a result of a variety of processes including transpiration, suspension of soil/sediment, volatilisation from water bodies (including near-surface aquifers) or soil/sediment, degassing, production of radon gas from the decay of natural and/or repository-derived uranium, thorium and radium, and direct discharge of gases from the geosphere. Contaminants may also enter the indoor atmosphere from: use of contaminated water in showers; suspension of dust brought in on clothing or footwear; or from infiltration of contaminated water and gases into basements.
The atmospheric system may represent a significant source of dilution for these contaminants. For example, advection and dispersion by wind can move contaminants from local to more dispersed regional areas. However, in the near-surface layer, contaminants such as ¹⁴C-labelled methane may be subject to uptake by plants.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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IAEA (), Dispersion of Radioactive Material in Air and Water and Consideration of Population Distribution in Site Evaluation for Nuclear Power Plants, IAEA Safety Guide, International Atomic Energy Agency, Vienna, NS-G-3.2, http://www-pub.iaea.org/MTCD/publications/PDF/Pub1122_scr.pdf, 28 February 2002
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IAEA (), Performance of Models in Radiological Impact Assessment for Normal Operation. Report of Working Group 1 Reference Methodologies for Controlling Discharges of Routine Releases of EMRAS II Topical Heading Reference Approaches for Human Dose Assessment, Environmental Modelling for Radiation Safety (EMRAS II) Programme, International Atomic Energy Agency, Vienna, IAEA-TECDOC-1808, http://www-pub.iaea.org/MTCD/publications/PDF/TE-1808_web.pdf, 31 December 2016