Description
The soils that are within a few metres of the land surface and typically underlain by unconsolidated overburden (see Figure 1) 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 soil type can be characterised by parameters such as particle-size distribution, inorganic and organic matter content. These will have different physical and chemical properties, different land management properties, and different contaminant migration properties. Microbial populations (or their absence) are an important component of soils. Typically, the top 0.2 to 0.3 m is the active surface soil region that contains the bulk of the plant roots, as well as being the region most directly affected by agricultural practices such as ploughing.
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 that might have migrated from the repository may become bound to the soil particles. Vegetation will receive a portion of their contamination via root uptake from surface soils. Both humans and non-human biota can be exposed directly to soil contamination via external exposure, and potentially inadvertent ingestion of soil, whilst spending time on top of or within the soil.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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G.Shaw (), Radioactivity in the Terrestrial Environment, Elsevier Science, 10, 306, https://www.elsevier.com/books/radioactivity-in-the-terrestrial-environment/shaw/978-0-08-043872-6 , 1 March 2007
Related Media
Images
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Distinct layers of soil, formally described as "horizons"
Image by Wilsonbiggs is licensed under CC BY-SA 4.0.