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)

    FEPs database

    The FEP database assembles features, events and processes for geological disposal as an aid to national programmes to identify, classify and screen FEPs in safety assessment. The database consists of two main parts:

    • The International FEP List – a comprehensive and structured list of factors relevant to the assessment of long-term safety of nuclear waste repositories.
    • Project Databases – a collection of FEP lists and databases, with references, compiled during repository safety assessment studies.

    An NEA publication on the Features, Events and Processes (FEPs) for the Geologic Disposal of Radioactive Waste was released in 1999. An updated version of the FEP database was completed in 2006; this version (2.1) can be downloaded as a zip file (4 Mb).

    In light of the findings from the 2010 questionnaire on “the use of FEPs in performance assessment studies and the scope for related NEA IGSC activities”, the NEA is supporting the revision of the NEA International FEP list and the associated database to ensure that they remain useful and relevant to the work of member states. The update of the International FEP list and database is currently being updated. More information of this work activities will be provided when available.

    Publications and 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