Integration Group for the Safety Case (IGSC): Safety Assessment Strategy and Tool

    IGSC activities in the field of Assessment Strategy and Tool evaluate effective assessment tools and strategies in developing and integrating a safety case. Activities in this area are designed to answer the question of "how do we use what we know to demonstrate safety?"


    With the emergence of the safety case concept in the past decades, the IGSC initiated a state-of-the-art review of safety assessment approaches in 2008. The goals of the MeSA project were to examine and document methods used in safety assessment for radioactive waste disposal facilities, to generate collective views and areas where different methodologies are used, and to identify future work. The project was concluded with a workshop in 2010 in which specific safety assessment strategy issues were evaluated. Seven (7) issue papers summarizing the latest knowledge on the below topics were produced as a result of the project. The MeSA Synthesis Report summarises the key findings of the issues papers.

    Publications and Reports

    • Methods for Safety Assessment for Geological Disposal Facilities for Radioactive Waste (2012)

    NEA FEP Database

    The NEA Feature, Event and Process (FEP) Database is an electronic tool which supports national programmes for radioactive waste management in the identification, classification and screening of FEPs. These are used when defining relevant scenarios for safety assessment for deep geological repositories (DGRs). The NEA FEP Database is composed of two parts:

    • International FEP (IFEP) List – a comprehensive and structured generic list of factors relevant to the assessment of the long-term safety of DGRs. The IGSC has been developing the IFEP List since the early 1990s. The IGSC continues to update the IFEP List following the most recent experience in safety assessment and its methodologies: after the first version – a milestone for the safety assessment of DGRs – was released in 2000, the version 2.0 and version 3.0 were published, respectively, in 2015 and 2019.
    • Project-specific FEP (PFEP) Lists – collections of FEP lists, with references, that have been developed by radioactive waste management organisations (RWMOs) as part of their safety assessments. Every FEP of each RWMO project database can be mapped to one or more of the international FEPs to demonstrate consistency.

    The past version of the database was implemented in a commercial standalone software package with custom tools to assist in locating and examining FEPs and related information. Several versions were produced, and included FEP lists from different types of repository project for different kinds of waste. The versions that were publically released are:

    • NEA2000 (Standalone NEA FEP Database 1.1) – This included the IFEP List 1.0 and 8 PFEP Lists;
    • NEA2006 (Standalone NEA FEP Database 2.1) – This included the IFEP List 1.0 and 11 PFEP Lists. Download.

    The new version of the NEA FEP Database, launched in 2018, moved to a web-based platform. This new database has been designed to allow full version control and is intended to provide a home for all release of the NEA IFEP List in future. Moreover, it is designed to allow RWMOs to upload and manage their own more recent and updated PFEP Lists.

    To access to the new web-based NEA FEP Database and to have an overview of the history of the evolution of the NEA IFEP List, please visit the database site.

    Publications, reports

    Scenario development

    A workshop on scenario development was organised in Madrid during May 1999, with the objective of reviewing developments in scenario methodologies and applications in safety assessments since 1992. In addition, a document on state-of-the-art scenario development is also available.

    Publications and Reports

    Safety indicators

    The concept of using various types of indicators to complement dose and risk has developed considerably during the last 15 years in national and international projects. Experience has been gained in international fora such as SPIN, PAMINA, INTESC and other national projects. The early emphasis on using just dose and risk as safety indicators has been extended, and several types of complementary indicators are now used, most recently safety function indicators.

    Within the scope of the NEA's Methods for Safety Assessment (MeSA) project, a questionnaire was distributed to IGSC members in 2010 to seek their experiences using indicators in performing safety assessments. Based on the responses of the Indicators Questionnaire, a follow-up question list was then distributed with the intent to delve deeper into specific key issues identified in the questionnaire. Results of the two question lists are documented in a status report. This report (to be published in the 2nd quarter of 2012) examines and documents the current status of methods for safety assessment for long-term safety of geological repositories for disposal of radioactive waste.

    Publications and Reports

    • Indicators in the Safety Case – An NEA Status Report (2012)

    Organisational aspects in confidence building

    In developing a safety case, the structure of an organization and the tools used to manage the development of a safety case are key components in effective integration of information and knowledge. The IGSC recognizes the need to further explore the topic of organizational aspects in confidence building. A task group has since been formed to further develop issues related to this particular topic. Further information will be provided when available.

    Last reviewed: 18 June 2014