Description

The dissolving of contaminants from the waste form into a solution on contact with water. For some waste forms (e.g. glass), this process can be very slow and result in the slow congruent release of contaminants contained within the waste form. For others, such as those with surface contamination or those that are readily soluble on contact with water, this process can be very rapid and result in the instantaneous release of contaminants contained within the waste form.

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.

  • 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.

Dissolution of a solid waste form by a coexisting liquid phase will release radionuclides or other contaminants from the waste form. The radionuclides or other contaminants will thereby be rendered potentially mobile. Such a liquid phase would be able to migrate into the surrounding engineered or natural barriers should the waste package be vented initially or be breached later in the post-closure period. The solubility of a radionuclide or other contaminant will govern its maximum concentration in the liquid phase (FEP 2.4.1.3). The solubility will also govern the rate at which a radionuclide or other contaminant dissolves in the coexisting liquid phase under any given set of conditions (temperature, pressure, liquid composition) prior to this maximum concentration being attained.

2000 List

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

3.2.01

Related References