Description

The inventory of radioactive isotopes (radionuclides) of all elements in the various waste forms disposed of in the repository. Included are the identities and quantities of radioactive isotopes that are present in the waste initially and those that might form subsequently by processes such as radioactive decay, activation.

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 radionuclide content is relevant to performance and safety because it describes the identities and quantities of radioactive waste constituents that potentially could be harmful should environmental receptors be exposed to them. The physical and chemical properties of each radionuclide (e.g. whether it can exist in different oxidation states, whether it is sorbing or non-sorbing, whether it partitions into liquid water or a gaseous phase, the rate of decay) are important controls on the mechanisms by which it may be released from the waste form and transported through engineered and natural barriers, potentially to the biosphere. The abundance and properties of each radionuclide in the waste form, in combination, will influence strongly the dose that an environmental receptor could receive, as calculated in a safety assessment. The natures and quantities of radionuclides will evolve over time as a result of processes such as radioactive decay and activation. The potential for mobilisation and the activities of radionuclides that are ingrown by these processes need to be taken into account by safety assessment.

2000 List

A reference to the related FEP(s) within the 2000 NEA IFEP List.

2.1.01

Related References