Description

The dissolution of evaporite minerals (halite, sylvite, etc.) by water, which may be the dominant component of a rock formation (e.g. a bedded halite formation or halite diapir), or which may be a minor component of a rock formation.

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.

Salt dissolution may influence the safety and performance of a repository by impacting upon the physical and chemical characteristics of a repository’s environment. Dissolution of salt may reduce the thickness of a salt formation or produce voids through which water and/or gas may move and transport radionuclides and / or other contaminants from the repository to the biosphere. These voids may occur where the salt has been removed by dissolution, or where overlying rocks have collapsed into the space produced by the salt dissolution. Salt dissolution will impact upon the salinity and composition of the groundwater. Very high groundwater salinities may be reached. The dissolved constituents originating in the salt will complex to some degree with any radionuclides and / or other contaminants with which they come into contact, affecting the partitioning of the radionuclides and / or contaminants between immobile and mobile phases. The solutes acquired by groundwater during salt dissolution will also influence the physical and chemical evolution of wastes and engineered barriers should such water enter the repository. For example, high Cl concentrations could act to promote corrosion of steel barrier components. The high groundwater salinities that may be acquired by groundwater due to salt dissolution will also influence the density of the groundwater. Density gradients may be established that will impact upon groundwater flow rates and directions.

2000 List

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

1.2.09