Description
The characteristics and properties of metallic 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 metallic waste forms control the release rates of radioactive and non-radioactive contaminants from the metals, and the physical and chemical forms in which these contaminants are released. The physical and chemical characteristics and properties will also influence how the waste form interacts with any other waste forms (e.g. organic materials or inorganic, non-metallic waste forms) in the same waste container, and with the waste container itself. Depending upon the physical and chemical characteristics of the metal in the waste form, these latter interactions may accelerate the rate at which containers degrade following an initial breach allowing water ingress. For example, a safety assessment may need to consider whether, following an initial breach, corrosion of the metals in the waste form may release hydrogen gas which then leads to pressurisation of the waste container. Corrosion of metals may be accompanied by volume changes that could impact upon the integrity of surrounding barriers (e.g. expansion causing stressing of containers). Corrosion products may take up radionuclides or other contaminants, by sorption or accommodation within crystal structures.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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Ahn J and Apted M (Eds) (2010). (), Geological Repository Systems for Safe Disposal of Spent Nuclear Fuels and Radioactive Waste, Woodhead Publishing, ISBN 9781845695422, http://store.elsevier.com/product.jsp?isbn=9781845699789
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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