International FEP List - Version 3.1
List Summary

Background

The Nuclear Energy Agency (NEA) “International FEP (IFEP) List” is a comprehensive and structured list of generic features, events and processes (FEPs), relevant to assessments of the post-closure safety of deep geological repositories (DGRs), which has been assembled through international collaboration between radioactive waste management organisations via the NEA. It is intended to support national programmes in their safety cases through the provision of a comprehensive and internationally accepted list of factors that may need considering in safety assessments of DGRs.

Version 3.0 of the IFEP List was developed following a review of various project-specific lists and databases [1] and was published in 2019 [2]. In commissioning the Version 3.0 IFEP List, the NEA Integration Group for the Safety Case (IGSC) agreed that it should be:

• relevant to all stages of a repository development programme, from inception to repository closure;
• relevant to both safety assessors and individual topic experts;
• limited to the post-closure safety of deep geological disposal facilities;
• relevant to all designs of geological disposal facilities;
• relevant to all categories of radioactive waste proposed for disposal in geological disposal facilities; and
• relevant to the assessment of the radiological and non-radiological impacts of contaminant releases on both humans and non-human biota.

Version 3.1 of the IFEP List also aims to meet these objectives, and has been produced following review of:

• SKB’s SE-SFL FEP Catalogue [3] to see if updates need to be made to the IFEP List; and
• the bibliographical references in the IFEP List to identify if any more recent technical references need to be added.

The reader should note that operational safety is beyond the scope of the current list, as are surface and near-surface disposal facilities (i.e. those on or within 30 m of the surface), borehole disposal and disposal in repositories either in pre-existing underground caverns/tunnels/mines or in close proximity to such facilities.

Structure and Content of the IFEP List

Consistent with the Version 3.0 IFEP List and many of the more recent project-specific FEP (PFEP) Lists (e.g. those from Finland, Japan and Sweden), the Version 3.1 IFEP List is structured around a classification scheme based on external factors and disposal components (waste package, repository, geosphere and biosphere), rather than on the 2000 IFEP List scheme that used external, environment and contaminant factors. The structure is hierarchical with the first and second level shown in Figure 1.

In total, there are 268 IFEPs (including FEP Groups and Subgroups).

Uses of the IFEP List

The IFEP List can be used in a number of ways:

• It can be used as a starting point for the development of a new PFEP List for geological disposal programmes that are in the early stages of planning. The PFEP List produced can then be used in the post-closure safety assessment of the repository, e.g. for the identification and development of scenarios and/or conceptual models for performance assessment.
• For more developed programmes, the IFEP List can be used to provide an audit to check the completeness of scenarios, conceptual models and/or their implementation in software tools for a particular safety assessment. Such an audit could be carried out by either the assessor or by a reviewer of the assessment.
• For PFEP Lists that have been developed independently from the updated IFEP List, the IFEP List can be used as an audit tool to check their completeness.

Specification

Each IFEP has a unique identification number and title, and utilises the properties listed in Figure 2. Links to references, from which further information can be obtained (documents or web-links), are included, as are media items, for example graphs, drawings or photos.