Description
The degradation of the metallic component(s) of the waste package by interaction with its environment, specifically, by reactions involving water in liquid or vapour form and / or gases (e.g. oxygen in the air), and/or by reaction with solutes within the water. Corrosion of the waste package can occur by a number of processes such as generalised (or uniform), localised and galvanic corrosion. Metals are subject to uniform corrosion at rates that are dependent on the chemical and physical (and possibly biological) environment, while localised formation of cavities in a metal surface is caused by non-uniform corrosion. Galvanic corrosion occurs when two different metals are in electric contact. Metal corrosion will result in the generation of hydrogen gas under anaerobic conditions.
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.
- Event
- 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.
Corrosion of the metal components of a waste package may influence: their mechanical properties; any capability to contain radionuclides or other contaminants; any capability to retard migration of radionuclides or other contaminants. Any corrosion of metallic waste forms will influence the release of radionuclides and other contaminants from these waste forms. Where a waste package offers containment initially, corrosion may lead to containment being lost. Where a waste package does not offer full containment initially (e.g. because it is vented), corrosion could decrease the resistance offered by the package to the migration of radionuclides or other contaminants. The ability of corroded metal components to retard the migration of radionuclides or other contaminants will depend upon the corrosion products (e.g. aerobic corrosion of steel may produce Fe-oxides onto which radionuclides can sorb). Corrosion may produce gas (e.g. hydrogen produced by anaerobic steel corrosion) or consume gas (e.g. oxygen consumption by aerobic steel corrosion). These processes may influence the redox conditions within and around the waste package (which may in turn impact release rates of radionuclides and other contaminants and the forms in which they are released). Gas production or consumption may also influence the pressures within and around the waste package.
2000 List
A reference to the related FEP(s) within the 2000 NEA IFEP List.
Related References
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R.W. Revie (eds.) (), Uhligs Corrosion Handbook, second edition, John Wiley and Sons
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Feron D (), Nuclear Corrosion Science and Engineering, 1st Edition, Woodhead Publishing, ISBN 9780081016343, http://store.elsevier.com/product.jsp?isbn=9780857095343
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Cottis B, Graham M, Lindsay R, Lyon S, Richardson T, Scantlebury D, Stott H (eds) (), Shreir’s Corrosion, Elsevier, Amsterdam, ISBN 978-0-444-52788-2, https://www.elsevier.com/books/shreirs-corrosion/richardson/978-0-444-52788-2