Description
The characteristics and properties of organic waste forms that may be disposed of in a repository.
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
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.
The physical and chemical characteristics of organic waste forms, including their geometries (dimensions and shapes, which affect surface area / volume ratios and void space) control the release rates of radioactive and non-radioactive contaminants from the organic materials, and the physical and chemical forms in which they are released. Examples of these waste forms include paper, cotton, rubber, plastics and resins. Organic materials may degrade to a wide range of products (including gases), and some degradation products may form mobile aqueous complexes with radionuclides. The physical and chemical characteristics and properties of the organic materials will also influence how the waste form interacts with any other waste forms (e.g. metals or non-metallic inorganic wastes) in the same waste container, and with the waste container itself and influence the overall chemical environment within the waste (e.g. pH and Eh). Depending upon the physical and chemical characteristics of the organic matter in the waste form, these latter interactions may help to accelerate the rate at which containers degrade. For example, a safety assessment may need to consider whether evolution of gas caused by degradation of organic wastes could potentially pressurise an unvented container and promote its failure.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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IAEA (), Handling and Processing of Radioactive Waste from Nuclear Applications, IAEA TRS 402, International Atomic Energy Agency, Vienna, http://www-pub.iaea.org/MTCD/Publications/PDF/TRS402_scr.pdf
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IAEA (), Predisposal Management of Organic Radioactive Waste, IAEA TRS-427, International Atomic Energy Agency, Vienna, http://www-pub.iaea.org/MTCD/publications/PDF/TRS427_web.pdf