Description

The physical, chemical and biological characteristics and properties of the seals in the waste emplacement rooms and access tunnels at repository closure. Sealing materials may include clay bricks, cement bricks and cement plugs.

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 characteristics of room / tunnel seals will impact the potential for radionuclides and other contaminants to migrate through / from the rooms and tunnels, should they be released from the waste packages. These room / tunnel seals may also influence the rate at which fluids (such as liquid water, non-aqueous liquids or gases) may enter or leave the repository in the post-closure period. The room / tunnel seals may therefore affect the rate at which the repository re-saturates following closure. Should the wastes and / or engineered barrier components evolve to produce gas, the permeability of the seals may influence the pressures that are attained.

The ability of the room / tunnel seals to affect fluid movement to the repository, including the resaturation rate, may impact upon the evolution of other engineered barrier components. Depending upon the chemical and biological characteristics of these seals, their volumes and their locations relative to the waste packages, they may impact upon the biology and chemistry of the environment around the waste packages.

2000 List

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

2.1.05

Related References