Nuclear Safety NEA/CSNI/R(2014)12 January 2015 www.oecd-nea.org Assessment of CFD Codes for Nuclear Reactor Safety Problems – Revision 2 Unclassified NEA/CSNI/R(2014)12 Organisation de Coopération et de Développement Économiques Organisation for Economic Co-operation and Development 16-Jan-2015 ___________________________________________________________________________________________ _____________ English text only NUCLEAR ENERGY AGENCY COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS Unclassified NEA/CSNI/R(2014)12 Assessment of CFD Codes for Nuclear Reactor Safety Problems - Revision 2 JT03369378 English text only 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. NEA/CSNI/R(2014)12 ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT The OECD is a unique forum where the governments of 34 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, Chile, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Luxembourg, Mexico, the Netherlands, New Zealand, Norway, Poland, Portugal, the Republic of Korea, the Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The European Commission 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. NUCLEAR ENERGY AGENCY The OECD Nuclear Energy Agency (NEA) was established on 1 February 1958. Current NEA membership consists of 31 countries: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, the Netherlands, Norway, Poland, Portugal, the Republic of Korea, the Russian Federation, the Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The European Commission 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 the 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. 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. Corrigenda to OECD publications may be found online at: www.oecd.org/publishing/corrigenda. © OECD 2014 You can copy, download or print OECD content for your own use, and you can include excerpts from OECD publications, databases and multimedia products in your own documents, presentations, blogs, websites and teaching materials, provided that suitable acknowledgment of the OECD as source and copyright owner is given. All requests for public or commercial use and translation rights should be submitted to [email protected]. Requests for permission to photocopy portions of this material for public or commercial use shall be addressed directly to the Copyright Clearance Center (CCC) at [email protected] or the Centre français d'exploitation du droit de copie (CFC) [email protected]. 2 NEA/CSNI/R(2014)12 COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS Within the OECD framework, the NEA Committee on the Safety of Nuclear Installations (CSNI) is an international committee made of senior scientists and engineers, with broad responsibilities for safety technology and research programmes, as well as representatives from regulatory authorities. It was set up in 1973 to develop and co-ordinate the activities of the NEA concerning the technical aspects of the design, construction and operation of nuclear installations insofar as they affect the safety of such installations. The committee’s purpose is to foster international co-operation in nuclear safety amongst the NEA member countries. The CSNI’s main tasks are to exchange technical information and to promote collaboration between research, development, engineering and regulatory organisations; to review operating experience and the state of knowledge on selected topics of nuclear safety technology and safety assessment; to initiate and conduct programmes to overcome discrepancies, develop improvements and research consensus on technical issues; and to promote the co-ordination of work that serves to maintain competence in nuclear safety matters, including the establishment of joint undertakings. The clear priority of the committee is on the safety of nuclear installations and the design and construction of new reactors and installations. For advanced reactor designs the committee provides a forum for improving safety related knowledge and a vehicle for joint research. In implementing its programme, the CSNI establishes co-operative mechanisms with the NEA’s Committee on Nuclear Regulatory Activities (CNRA) which is responsible for the programme of the Agency concerning the regulation, licensing and inspection of nuclear installations with regard to safety. It also co-operates with the other NEA’s Standing Committees as well as with key international organizations (e.g., the IAEA) on matters of common interest. 3 NEA/CSNI/R(2014)12 ASSESSMENT OF CFD FOR NUCLEAR REACTOR SAFETY PROBLEMS B. L. Smith (PSI), M. Andreani (PSI), U. Bieder (CEA), F. Ducros (CEA), E. Graffard (IRSN), M. Heitsch (GRS), M. Henriksson (Vattenfall), T. Höhne (FZD), M. Houkema (NRG), E. Komen (NRG), J. Mahaffy (PSU), F. Menter (ANSYS), F. Moretti (UPisa), T. Morii (JNES), P. Mühlbauer (NRI), U. Rohde (HZDR), M. Scheuerer (GRS), C.-H. Song (KAERI), T. Watanabe (JAEA), G. Zigh (US NRC) With additional input from F. Archambeau (EDF), S. Bellet (EDF), D. Bestion (CEA), C. F. Boyd (US NRC), E. Krepper (HZDR), J.M. Muñoz-Cobo (UPV), J.-P. Simoneau (AREVA) 4 NEA/CSNI/R(2014)12 EXECUTIVE SUMMARY Original Initiative Following recommendations made at an “Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety (NRS) Problems”, held in Aix-en-Provence, France, 15-16 May, 2002, and a follow-up meeting “Use of Computational Fluid Dynamics (CFD) Codes for Safety Analysis of Reactor Systems including Containment”, which took place in Pisa on 11-14 Nov., 2002, a CSNI action plan was drawn up which resulted in the creation of three Writing Groups, with mandates to perform the following tasks: (1) Provide a set of guidelines for the application of CFD to NRS problems; (2) Evaluate the existing CFD assessment bases, and identify gaps that need to be filled; (3) Summarise the extensions needed to CFD codes for application to two-phase NRS problems. Work began early in 2003. In the case of Writing Group 2 (WG2), a preliminary report was submitted to WGAMA in September 2004 that scoped the work needed to be carried out to fulfil its mandate, and made recommendations on how to achieve the objective. A similar procedure was followed by the other two groups, and in January 2005 all three groups were reformed to carry out their respective tasks. In the case of WG2, this resulted in the issue of a CSNI report (NEA/CSNI/R(2007)13), issued in January 2008, describing the work undertaken. Background Computational methods have been used in the safety analysis of reactor systems for nearly 40 years. During this time, very reliable numerical programs have been developed for analysing the primary system, and similar programs have also been written for modelling containments and severe accident scenarios. Such codes model the reactor components as networks of 1-D or even 0-D cells. It is evident, however, that the flows in many reactor primary components are essentially 3-D in character, as is natural circulation, mixing and stratification