Application and Selection of Nuclear Event Investigation Methods, Tools and Techniques

This final report presents the results gained in the last step of a project launched in the frame of technical task “Comparative study of event assessment methodologies with recommendations for an optimized approach in the EU” for 2010 -2011. It contains analysis and evaluation of the existing practices and some developed conclusions and recommendations to facilitate selection and implementation of relevant instruments to improve quality of nuclear event investigations. Study is based on the results of the performed survey with participation of experts from nuclear power plants and regulatory bodies representing 12 European countries and USA. Main attention was paid to analysis of the existing practices and organizational aspects of nuclear event investigation, as well as to qualitative evaluation of currently employed event investigation methods, tools and techniques. Some methodological inconsistencies, existing barriers, bottlenecks and emerging traps in event investigation process were identified and analyzed more thoroughly. In order to avoid the existing ambiguities and misunderstandings in system of terms and definitions, used in event investigation and root cause analysis concretely, the several improved definitions were suggested. Aiming to distinguish better event investigation instruments of different levels and applicability, the original system of classification of basic root cause analysis methods and tools was suggested. This system should facilitate comparison of characteristics and selection of the most relevant instruments for event investigation. Some methodological and practical recommendations how to conduct analysis overcoming the identified obstacles were put forward. The detailed recommendations for selection of root cause analysis methods and tools are presented as well.JRC.F.5-Nuclear Reactor Safety Assessmen