OECD/CSNI Workshop on Best Estimate Methods and Uncertainty Evaluations - Workshop Proceedings

Best-Estimate Methods plus Uncertainty Evaluation are gaining increased interest in the licensing process. On the other hand, lessons learnt from the BEMUSE (NEA/CSNI/R(2011)3) and SM2A (NEA/CSNI/R(2011)3) benchmarks, progress of UAM benchmark, and answers to the WGAMA questionnaire on the Use of Best-Estimate Methodologies show that improvements of the present methods are necessary and new applications appear. The objective of this workshop is to provide a forum for a wide range of experts to exchange information in the area of best estimate analysis and uncertainty evaluation methods and address issues drawn-up from BEMUSE, UAM and SM2A activities. Both, improvement of existing methods and recent new developments are included. As a result of the workshop development, a set of recommendations, including lines for future activities were proposed. The organisation of the Workshop was divided into three parts: Opening session including key notes from OECD and IAEA representatives, Technical sessions, and a Wrap-up session. All sessions included a debate with participation from the audience constituted by 71 attendees. The workshop consisted of four technical sessions: a) Development achievements of BEPU methods and State of the Art: The objective of this session was to present the different approaches to deal with Best Estimate codes and uncertainties evaluations. A total of six papers were presented. One initial paper summarized the existing methods; the following open papers were focused on specific methods stressing their bases, peculiarities and advantages. As a result of the session a picture of the current State of the Art was obtained. b) International comparative activities: This session reviewed the set of international activities around the subject of BEPU methods benchmarking and development. From each of the activities a description of the objectives, development, main results, conclusions and recommendations (in case it is finalized) was presented. This session comprised a total of four papers. c) Applications: licensing, safety analysis support, regulatory body views and industry activities: This session put the focus on the application of current methods in safety analyses. Contribution from industry, technical safety organizations and regulatory bodies was present. As a result, a view of the penetration of BEPU methods in current safety analyses was obtained, as well as an indication of the evolution in the near future. Elements such as licensing practices, assessment process, etc. were considered. This session comprised nine papers. d) BEPU methods extension to new fields: Since the early days of BEPU methods development it was realized that this approach could be extended and its benefits applied to other areas beyond the classic deterministic environment. This session was focused on the extension of BEPU methods beyond this point. The session developed the extension to CFD, quantification of global safety margins, use of PSA, etc. with a total of seven papers