Description

The physical deformation of rocks to produce geological structures in response to, or involved in, geological processes such as tectonic movement, orogeny, magmatism, seismicity, diapirism and differential vertical movements, caused e.g. by loading and unloading of the crust by glaciation/deglaciation or by sedimentation/erosion. Deformation can include faulting, fracturing, extrusion, (de)compression of rocks and can result in basin formation or mountain formation. Compressional or tensional forces in the Earth’s crust may result in the activation of existing faults and the generation of new faults. It also includes deformation caused by the movement of high plasticity and low-density material, such as salt, mud or magma, into more brittle and dense overlying rocks.

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.

Deformation, whether elastic, plastic or brittle has, depending upon its spatial scale, the potential to affect the spatial disposition of a repository with respect to potential environmental receptors (e.g. the future spatial separation between a repository and the biosphere). Plastic or brittle deformation may impact upon the integrity of engineered barriers within a repository and upon the integrity of the surrounding natural geosphere barriers. Plastic deformation may cause thickening or thinning of barriers, whether engineered or natural (e.g. thinning of halite due to creep). Brittle deformation could potentially produce transmissive faults and fractures through which groundwater, other liquids and gas might flow, transporting radionuclides and other contaminants as they do so. Deformation could also influence the forces that may drive the movement of water, other liquids and gases through and around the repository. For example, deformation may affect the orientations and magnitudes of water pressure gradients. Deformation may be initiated by tectonic movements (FEP 1.2.1) or take place during orogenesis (FEP 1.2.2). However, other processes could cause deformation, such as magmatism (FEP 1.2.5), diapirism, and loading and unloading of the crust by glaciation/deglaciation (FEP 1.3.5) or by sedimentation/erosion (FEP 1.2.8).

2000 List

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

1.2.02

Related References