Description

The design and layout of the repository, including both the safety concept, i.e. the general features of design, including the repository barriers and their safety functions, and the more detailed engineering specification for repository construction, operation and closure. Initially, the repository conceptual design and layout are based on expected host rock characteristics, waste and backfill characteristics, construction technology, and economics and there may be a range of potential options. As the repository project proceeds, the number of options will reduce to one. As the repository is constructed, modifications might need to be made to the layout or other aspects of design to account for specific rock conditions. In certain cases, the repository might be developed from an existing mine and thus its layout could be pre-determined to a significant extent.

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 design, layout and safety concept of the repository will influence the contribution of each engineered and natural barrier to overall safety. The design, layout and the safety concept must be appropriate for meeting the required safety criteria in the specific geological environment within which the repository is to be constructed. The design must be matched to the kinds of wastes that are to be emplaced, accounting for the packaging of the wastes, and must allow operations to be undertaken. The layout of the repository will determine the density with which wastes are emplaced and the locations of the emplaced wastes with respect to natural barriers and permeable features such as transmissive fracture zones. These factors will influence safety. The safety concept defines the safety functions of each natural and engineered component of the repository.

2000 List

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

1.1.07

Related References