Description
The physical, chemical and biological characteristics and properties of the waste forms at the time of emplacement in the repository. This includes the mass and volume of each waste form type, as well as information on the associated thermal, hydraulic, chemical and mechanical characteristics. The phase characteristics (solid, gas or liquid) is also covered by this FEP.
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 the waste form control the release rates of radioactive and non-radioactive contaminants, and the physical and chemical forms in which they are released from the waste form. Waste forms may be metallic, organic or non-metallic and inorganic in nature. Some waste forms may also be in liquid or gas phase. The physical and chemical characteristics and properties will also influence how the different components of the waste form interact with each other and with the waste container. Depending upon the physical and chemical characteristics of the waste form, these latter interactions may influence the integrity of the containers. For example, the alkaline environment maintained by cementitious waste forms may help to decrease the corrosion rate of an iron or steel container. On the other hand, the possibility that bituminous waste forms may expand due to radiolysis, thereby impacting upon the container, may need to be considered by a safety assessment.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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National Research Council (), Waste Forms Technology and Performance: Final Report, Committee on Waste Forms Technology and Performance, Nuclear and Radiation Studies Board Division of Earth and Life Studies, The National Academies Press, Washington D.C., ISBN 978-0-309-18733-6, ISBN 0-309-18733-8, https://www.nap.edu/catalog/13100/waste-forms-technology-and-performance-final-report
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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