Indicators in the Safety Case, A report of the Integrated Group on the Safety Case (IGSC)

JT03324920 Complete document available on OLIS in its original format This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area. The last several years have seen a number of important developments in the use of indicators in safety cases for geological disposal. The NEA has reviewed these developments within the scope of its Methods for Safety Assessment (MeSA) project, and this Status Report presents the findings of that review. This review began by evaluating relevant aspects of previous NEA initiatives into safety cases, in particular the International Experience in Safety Cases (INTESC), Long-Term Safety Criteria (LTSC) and Timescales initiatives, as well as key publications from other international agencies such as the IAEA and EC. That evaluation confirmed the growing international interest in the subject but also highlighted a clear lack of consistency in the terminology, characteristics and methods of application of the indicators used by different organisations. To understand the situation better, a questionnaire was developed that included a number of questions grouped under the headings of (i) regulatory context and guidance, (ii) status of repository development programme, (iii) use of complementary indicators, and (iv) areas of uncertainty and future development. The Indicators Questionnaire was circulated to implementing organisations and regulatory agencies in Member States in February 2010, and twenty one separate responses were received that covered a range of experiences from developing assessment programmes just beginning to consider how to use indicators, to mature programmes that have already performed detailed site-specific assessments. The responses to the Indicators Questionnaire provided the primary source material for this Status Report, together with the outcomes from comparable international work, in particular relevant IAEA Technical Reports and the EC's SPIN and PAMINA Project reports. The main purpose of this Status Report is to increase awareness and understanding of the potential applications of indicators in the safety case, and provide support for further development in the area. Some guidance on the possible use of indicators is given but it is not the objective to seek to propose a 'standard' approach or terminology. This would be neither sensible nor possible given the differences in national regulations concerning their requirements for how indicators should be applied. For the sake of clarity, however, in this report an important distinction is made …