Radioactive Waste Management Linkage of Geoscientific Arguments and Evidence in Supporting the Safety Case Second AMIGO Workshop Proceedings Toronto, Canada 20-22 September 2005 © OECD 2007 NEA No. 6119 NUCLEAR ENERGY AGENCY ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT The OECD is a unique forum where the governments of 30 democracies work together to address the economic, social and environmental challenges of globalisation. The OECD is also at the forefront of efforts to understand and to help governments respond to new developments and concerns, such as corporate governance, the information economy and the challenges of an ageing population. The Organisation provides a setting where governments can compare policy experiences, seek answers to common problems, identify good practice and work to co-ordinate domestic and international policies. The OECD member countries are: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Korea, Luxembourg, Mexico, the Netherlands, New Zealand, Norway, Poland, Portugal, the Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities takes part in the work of the OECD. OECD Publishing disseminates widely the results of the Organisation’s statistics gathering and research on economic, social and environmental issues, as well as the conventions, guidelines and standards agreed by its members. * * * This work is published on the responsibility of the Secretary-General of the OECD. The opinions expressed and arguments employed herein do not necessarily reflect the official views of the Organisation or of the governments of its member countries. NUCLEAR ENERGY AGENCY The OECD Nuclear Energy Agency (NEA) was established on 1st February 1958 under the name of the OEEC European Nuclear Energy Agency. It received its present designation on 20th April 1972, when Japan became its first non-European full member. NEA membership today consists of 28 OECD member countries: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, the Netherlands, Norway, Portugal, Republic of Korea, the Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities also takes part in the work of the Agency. The mission of the NEA is: to assist its member countries in maintaining and further developing, through international co-operation, the scientific, technological and legal bases required for a safe, environmentally friendly and economical use of nuclear energy for peaceful purposes, as well as to provide authoritative assessments and to forge common understandings on key issues, as input to government decisions on nuclear energy policy and to broader OECD policy analyses in areas such as energy and sustainable development. Specific areas of competence of the NEA include safety and regulation of nuclear activities, radioactive waste management, radiological protection, nuclear science, economic and technical analyses of the nuclear fuel cycle, nuclear law and liability, and public information. The NEA Data Bank provides nuclear data and computer program services for participating countries. In these and related tasks, the NEA works in close collaboration with the International Atomic Energy Agency in Vienna, with which it has a Co-operation Agreement, as well as with other international organisations in the nuclear field. © OECD 2007 No reproduction, copy, transmission or translation of this publication may be made without written permission. Applications should be sent to OECD Publishing: [email protected] or by fax (+33-1) 45 24 99 30. Permission to photocopy a portion of this work should be addressed to the Centre Français d’exploitation du droit de Copie (CFC), 20 rue des Grands-Augustins, 75006 Paris, France, fax (+33-1) 46 34 67 19, ([email protected]) or (for US only) to Copyright Clearance Center (CCC), 222 Rosewood Drive Danvers, MA 01923, USA, fax +1 978 646 8600, [email protected]. FOREWORD The long-term safety of a deep geological repository for radioactive waste will be strongly dependent on the performance of the geosphere. The geosphere potentially isolates the radioactive waste from possible future intrusions by humans; provides a stable physical and chemical environment for the engineered barriers within the repository, insulating against external perturbations such as earthquakes and climate change; and prevents, delays and attenuates radionuclide transport by virtue of its hydraulic and sorptive properties. A safety case for a deep geological repository typically makes use of geoscientific information within a long-term safety assessment that evaluates potential impacts. These studies require a conceptual model of the geosphere that quantifies, for instance, groundwater flow rates and consequent radionuclide transport. However, geoscientific information can play a larger role in the safety case. In particular, geoscience can offer multiple and independent lines of evidence (qualitative and quantitative) to support a safety case. Moreover, geoscience can play an important role in other repository activities that bear on safety, such as site selection and repository design. AMIGO, an OECD/NEA international project on Approaches and Methods for Integrating Geological Information in the Safety Case, brings together geoscientists from across the international community, most of whom are involved in studies on deep geological repositories. AMIGO is organised as a series of biennial workshops with sessions that include comprehensive technical presentations from the host organisation, plenary discussions on topical issues, and small group discussions concentrating on specific questions. Each of these sessions has a single unifying goal: to enhance the role of geoscience in the safety case. The AMIGO workshops generally focus on improving the use of geoscientific information in the safety case, and more specifically on: • the role of the geosphere and its representation in the safety case; • capabilities of site characterisation versus the needs of safety assessment modelling and the safety case; and • procedures that encourage integration of a wide range of geoscientific information to contribute to the safety case more effectively. The first AMIGO workshop (AMIGO-1) was held in Yverdon-les-Bains, Switzerland in June 2003, and was hosted by the Swiss National Co-operative for the Disposal of Radioactive Waste (Nagra), the Swiss Federal Nuclear Safety Inspectorate (HSK) and the University of Bern. Amongst the topics investigated was the use of multiple lines of evidence to build confidence in the geoscientific understanding that underlies the safety case. These proceedings present the outcomes of the second AMIGO workshop (AMIGO-2), held in Toronto, Canada in September 2005 and hosted by Ontario Power Generation (OPG) and the Canadian Nuclear Safety Commission (CNSC). This second workshop expanded upon the AMIGO-1 deliberations to examine how geoscientific arguments and evidence are linked in supporting a safety case. It also examined the extrapolation and transfer of geoscientific information in time and space, and the practicalities of collecting, linking and communicating this information. 3 Acknowledgements On behalf of all participants, the NEA wishes to express its gratitude to Ontario Power Generation and the Canadian Nuclear Safety Commission who hosted the workshop in Toronto, Canada. Special thanks are also expressed to the following individuals: • Members of the AMIGO Steering Group,1 who were responsible for the management of the AMIGO workshop series as a whole, and who set the general objectives for this and the first AMIGO workshops. • Members of the Scientific Programme Committee,2 who were responsible for the detailed planning of this second AMIGO workshop, and who defined the lists of issues to be considered during the plenary and working group presentations. • The working group chairpersons and rapporteurs, who led and summarised the debates that took place in the four working groups, and who presented their observations during the final plenary discussion. • The speakers for their interesting and stimulating presentations, and all participants for their active and constructive contributions. These proceedings drew from presentations made at the workshop, including introductory comments by Rick Beauheim, a summary of the AMIGO-1 workshop by Andreas Gautschi, summary comments by the session chair- and co-chairpersons, reports crafted by the working group rapporteurs with the assistance of the group chairperson and participants, and concluding remarks by Johan Andersson. The draft proceedings were prepared by Bruce Goodwin and Mark Jensen and reviewed by members of the Steering Group and the Scientific Programme Committee. 1. Klaus-Jürgen Röhlig (GRS Köln, chair), Johan Andersson (Streamflow AB), Rick Beauheim (SNL), Gérard Bruno (IRSN), Andreas Gautschi (Nagra), Mark Jensen (OPG), Patrick Lebon (Andra) and Sylvie Voinis (NEA). 2. Rick Beauheim (SNL, chairperson), Johan Andersson, (Streamflow; SKB representative), Bruce Goodwin (GEACI, OPG representative), Mark Jensen (OPG, co-chairperson and host), Vincent Nys (AVN), Shizong Lei (CNSC), Georges Vigneron (Andra) and Sylvie Voinis