Nuclear Safety NEA/CSNI/R(2016)6/VOL1 March 2016 www.oecd-nea.org R eactivity Initiated Accident (RIA) Fuel Codes Benchmark Phase-II Volume 1: Simplified Cases Results Summary and Analysis Unclassified NEA/CSNI/R(2016)6/VOL1 Organisation de Coopération et de Développement Économiques Organisation for Economic Co-operation and Development 19-Apr-2016 ___________________________________________________________________________________________ _____________ English text only NUCLEAR ENERGY AGENCY COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS UN nE cA la/ sC sS i fiN eI d/R (2 0 1 6 ) 6 /V O L 1 Reactivity Initiated Accident (RIA) Fuel Codes Benchmark Phase-II Report - Volume 1 Simplified Cases Results Summary and Analysis JT03394281 E n Complete document available on OLIS in its original format glis Tinhteisr ndaotciuonmaeln ftr oanntdi earns ya mnda pb oinucnlduadreides h aenrdei nto atrhee wniathmoeu ot fp arenjyu dteircrei ttoor tyh, ec isttya oturs a orfe ao.r sovereignty over any territory, to the delimitation of h t e x t o n ly NEA/CSNI/R(2016)6/VOL1 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. 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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 2016 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(2016)6/VOL1 COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS The NEA Committee on the Safety of Nuclear Installations (CSNI) is an international committee made up of senior scientists and engineers with broad responsibilities for safety technology and research programmes, as well as representatives from regulatory authorities. It was created 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 among NEA member countries. The main tasks of the CSNI 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 reach 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 priority of the CSNI 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 Committee on Nuclear Regulatory Activities (CNRA), which is responsible for issues concerning the regulation, licensing and inspection of nuclear installations with regard to safety. It also co-operates with other NEA Standing Technical Committees, as well as with key international organisations such as the International Atomic Energy Agency (IAEA), on matters of common interest. 3 NEA/CSNI/R(2016)6/VOL1 ACKNOWLEDGEMENTS This report is prepared by the RIA Benchmark Phase II Task Group of the Working Group of Fuel Safety (WGFS). Special gratitude is expressed to Olivier Marchand (IRSN, France) for drafting the report, to Pierre Ruyer (IRSN, France) for his efforts in drafting Chapter 0 of the report, as well as to Marco Cherubini (NINE, Italy), Vincent Georgenthum (IRSN, France), Luis Enrique Herranz (CIEMAT, Spain), Lars Olof Jernkvist (Quantum Technologies, Sweden), Marc Petit (IRSN, France), Patrick Raynaud (NRC, USA) and Jinzhao Zhang (TRACTEBEL, Belgium) for reviewing the report. The following WGFS members and experts performed calculations and provided valuable input to various chapters of the report: Asko ARKOMA,VTT, Finland Felix BOLDT, GRS, Germany Heng BAN, INL, United States Marco CHERUBINI, NINE, Italy Adrien DETHIOUX, Tractebel (ENGIE), Belgium Thomas DRIEU, Tractebel (ENGIE), Belgium Charles FOLSOM, INL, United States Vincent GEORGENTHUM, IRSN, France Patrick GOLDBRONN, CEA, France Luis Enrique HERRANZ, CIEMAT, Spain Lars Olof JERNKVIST, Quantum Technologies, Sweden Hyedong JEONG, KINS, Korea Jan KLOUZAL, UJV, Czech Republic Olivier MARCHAND, IRSN, France István PANKA, MTA EK, Hungary Patrick RAYNAUD, NRC, United States José M. REY GAYO, CSN, Spain Pierre RUYER, IRSN, France Inmaculada C. SAGRADO GARCIA, CIEMAT, Spain Jérôme SERCOMBE, CEA, France, Heinz Günther SONNENBERG, GRS, Germany Gerold SPYKMAN, TÜV NORD, Germany Yutaka UDAGAWA, JAEA, Japan Jinzhao ZHANG, Tractebel (ENGIE), Belgium 4 NEA/CSNI/R(2016)6/VOL1 LIST OF ABBREVIATIONS AND ACRONYMS BWR Boiling-water reactor CABRI Test reactor in France Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas CIEMAT (Spain) CSN Consejo de seguridad nuclear (Spain) CSNI Committee on the Safety of Nuclear Installations (NEA) CZP Cold Zero Power DNB Departure from nucleate boiling FGR Fission-gas release FWHM Full Width at Half Maximum GRS Gesellschaft für Anlagen- und Reaktorsicherheit (Germany) HZP Hot Zero Power INL Idaho National Laboratory (United States) IRSN Institut de radioprotection et de sûreté nucléaire (France) JAEA Japan atomic energy agency KINS Korean Institute of Nuclear safety MOX Mixed oxide fuel (U and Pu) MTA EK Centre of Energy Research, Hungarian Academy of Sciences NEA Nuclear Energy Agency (OECD) NINE Nuclear and INdustrial Engineering (Italy) NRC Nuclear Regulatory Commission (United States) NSRR Nuclear safety research reactor (Japan) OECD Organisation for Economic Co-operation and Development PCMI Pellet-cladding mechanical interaction PWR Pressurised-water reactor RIA Reactivity-initiated accident SSM Strålsäkerhetsmyndigheten (Swedish Radiation Safety Authority) TRACTEBEL Tractebel Engineering (ENGIE) 5 NEA/CSNI/R(2016)6/VOL1 TSO Technical Support Organisation TUV Technischer überwachungsverein (Germany) UJV Nuclear research institute (Czech Republic), ÚJV Řež VTT Valtion Teknillinen Tutkimuskeskus/Technical Research Centre of Finland WGFS Working Group on Fuel Safety (NEA/CSNI) xD x-dimensional (where x is for 1.5, 2 and 3) 6 NEA/CSNI/R(2016)6/VOL1 TABLE OF CONTENTS LIST OF FIGURES ......................................................................................................................................... 9 LIST OF TABLES ........................................................................................................................................ 12 EXECUTIVE SUMMARY ........................................................................................................................... 13 1. BACKGROUND AND INTRODUCTION ............................................................................................. 17 2. SUMMARY OF SPECIFICATIONS ...................................................................................................... 21 3. PARTICIPANTS AND CODES USED ................................................................................................... 25 4. RESULTS SUMMARY AND ANALYSIS ............................................................................................. 29 4.1 Use of input data ............................................................................................................................... 29 4.2 Thermal behaviour ............................................................................................................................ 30 4.2.1 Analysis of initial state ........................................................................................................... 30 4.2.2 Analysis of overall transient behaviour .................................................................................. 32 4.2.3 Analysis of heat-up phase....................................................................................................... 42 4.3 Mechanical behaviour ....................................................................................................................... 45 4.3.1 Analysis of initial state ........................................................................................................... 46 4.3.2 Analysis of overall transient behaviour .................................................................................. 48 4.3.3 Analysis of heat-up phase....................................................................................................... 58 4.3.4 Influence of clad temperature ................................................................................................. 63 4.3.5 Influence of clad/fuel modelling ............................................................................................ 64 5. RIA THERMAL HYDRAULICS – STATE-OF-THE-ART REVIEW................................................... 69 5.1 Introduction ...................................................................................................................................... 69 5.2 High clad temperature transients during a RIA ................................................................................ 70 5.2.1 Quantities of interest ............................................................................................................... 70 5.2.2 A high temperature phase that appears for large enthalpy insertion ...................................... 70 5.2.3 Main difficulties to model the heat transfer coefficient ......................................................... 73 5.2.4 Partial conclusion ................................................................................................................... 75 5.3 Boiling flows of interest for RIA-related heat transfer ..................................................................... 75 5.3.1 The onset of boiling ................................................................................................................ 75 5.3.2 Nucleate boiling ..................................................................................................................... 75 5.3.3 Departure from Nucleate boiling ............................................................................................ 76 5.3.4 Film boiling ............................................................................................................................ 76 5.3.5 Rewetting ............................................................................................................................... 78 5.3.6 Wettability of the fluid onto the wall and boiling .................................................................. 78 5.3.7 Models for the boiling curve .................................................................................................. 78 5.4 Analysis of the different phases of the RIA-related boiling heat transfer ........................................ 79 5.4.1 Till the peak heat flux ............................................................................................................. 79 5.4.2 Transition toward film boiling and peak cladding temperature ............................................. 80 5.4.3 Film boiling till quenching ..................................................................................................... 81 7 NEA/CSNI/R(2016)6/VOL1 5.5 Conclusion ........................................................................................................................................ 84 6. CONCLUSIONS AND RECOMMENDATIONS ................................................................................... 85 7. REFERENCES ......................................................................................................................................... 87 8. APPENDIX I: GENERAL DESCRIPTION OF THE CODES ............................................................... 92 8.1 ALCYONE V1.4 .............................................................................................................................. 93 8.2 BISON .............................................................................................................................................. 95 8.3 FRAPTRAN ..................................................................................................................................... 96 8.4 RANNS ............................................................................................................................................. 98 8.5 SCANAIR ......................................................................................................................................... 99 8.6 TESPAROD.................................................................................................................................... 101 8.7 TRANSURANUS ........................................................................................................................... 103 9. APPENDIX II: SPECIFIC DESCRIPTION OF THERMAL HYDRAULICS MODELS USED IN CODES .................................................................................................................................. 105 9.1 ALCYONE ..................................................................................................................................... 105 9.2 BISON ............................................................................................................................................ 106 9.3 FRAPTRAN ................................................................................................................................... 109 9.3.1 Standard Version ................................................................................................................... 109 9.3.2 TRABCO coupling................................................................................................................ 110 9.4 RANNS ........................................................................................................................................... 111 9.5 SCANAIR ....................................................................................................................................... 115 9.5.1 Standard Version ................................................................................................................... 115 9.5.2 QT-COOL Model .................................................................................................................. 124 9.6 TESPAROD.................................................................................................................................... 126 9.7 TRANSURANUS ........................................................................................................................... 128 8