International Atomic Knerg> Agentv IAEA-TC-560.03 X1J COMPUTER AIDED SAFETY ANALYSIS 1989 PROCEEDINGS OF A TECHNICAL COMMITTEE/WORKSHOP ORGANIZED BY THE INTERNATIONAL ATOMIC ENERGY AGENCY AND HELD IN BERLIN. 17-21 APRIL 1989 INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1990 > / >X / COMPUTER AIDED SAFETY ANALYSIS 1989 PROCEEDINGS OF A TECHNICAL COMMITTEE/WORKSHOP ORGANIZED BY THE INTERNATIONAL ATOMIC ENERGY AGENCY AND HELD IN BERLIN, 17-21 APRIL 1989 I V •i INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1990 r >/ COMPUTER AIDED SAFETY ANALYSIS 1989 IAEA, VIENNA, 1990 IAEA-TC-560.03 Printed by the IAEA in Austria April 1990 FOREWORD The Technical Committee/Workshop on Computer Aided Safety Analysis was organized by the IAEA in cooperation with the National Board for Safety and Radiological Protection (SAAS) of the German Democratic Republic in Berlin. The purpose of the meeting was to provide an opportunity for discussions on experiences in the use of computer codes used for safety analysis of nuclear power plants. In particular it was intended to provide a forum for exchange of information among experts using computer codes for safety analysis under the Technical Cooperation Programme on Safety of WWER Type Reactors (RER/9/004) and other experts throughout the world. The detailed programme of the meeting, containing a list of all papers presented, is shown in Annex 1. The meeting was conducted in a workshop style, to encourage involvement of all participants during the discussions. Forty five (45) experts'from 19 countries, plus 22 experts from the GDR participated in the meeting. A list of participants can be found at the end of this volume. Forty-two (42) papers were presented and discussed during the meeting. Additionally an open discussion was held on the possible directions of the IAEA programme on Computer Aided Safety Analysis. A summary of the conclusions of these discussions is presented in the following section. The remainder of this proceedings volume comprises the transcript of selected technical papers presented in the meeting. It is the intention of the IAEA that the publication of these proceeding will extend the benefits of the discussions held during the meeting to a larger audience throughout the world. EDITORIAL NOTE In preparing this material for the press, staff of the International Atomic Energy Agency have mounted and paginated the original manuscripts as submitted by the authors and given some attention to the presentation. The views expressed in the papers, the statements made and the general style adopted are the responsibility of the named authors. The views do not necessarily reflect those of the governments of the Member States or organizations under whose auspices the manuscripts were produced. The use in this book of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of specific companies or of their products or brand names does not imply any endorsement or recommendation on the part of the IAEA. Authors are themselves responsible for obtaining the necessary permission to reproduce copyright material from other sources. > / CONTENTS SUMMARY OF DISCUSSIONS 7 IAEA activities in computer aided safety analysis 13 C. Almeida Experience of participants from the German Democratic Republic in DBA analysis for VVERs in the framework of the IAEA regional programme RER/9/004 28 D. Hennig, H. W. Roder, E. Adam, H. Hilse, K. Horche Applications of safety analysis codes at the Institute of Atomic Energy, Beijing 34 Erjun Yu The GRS thermalhydraulic system code ATHLET 41 H. Austregesilo, J.E. Miro, V. Teschendorff ICARE, a computer code for severe fuel damage analysis — general description of the second version, ICARE2 49 P. Chatelard, R. Gonzalez, F. Jacq, A. Porrachia Large nuclear reactor transient simulation 68 A.I. lonov, V.M. Panin, L.N. Podlazov, V.D. Rogova, T.Yu. Sakharova, B.E. Trekhov Verification of computer codes used in licensing 75 J. Hôhn, J. Rumpf Comparison of PMK-NVH experimental results in the event of 7.4% cold and hot leg breaks 79 G. Ézsôl, L. Szabados Post-test calculation of SPE-2 with RELAP5/MOD2 98 S. Petelin, I. Parzer, M. Gregoric, B. Mavko, A. Stritar, M. Osredkar Post-test analysis of SPE-2 with TRAC-PFl 105 M.R.S. Galetti, A.A. Madeira, R.C. Borges, A.C. Pontedeiro Thermohydraulic analysis for supporting PSA of SB LOCA in WWER-440 113 M. Kulig, J. Szczurek Emergency operating procedures for SGTR sequence 121 M. Gregoric, S. Petelin, B. Mavko, I. Parzer Post-test analysis of natural circulation, flow coastdown, and pressurizer spray tests in a large four loop PWR using RELAP5/MOD2 127 C.R. Brain Safety of the advanced VVER-1000 in condition of failure of the emergency protection system 133 N.S. Fil, B.E. Volkov, LA. Latyeva, G.V. Aljekhin Computer operating support system of NPP main equipment 140 N.N. Lebedev, O.N. Glasov, L.N. Podlazov Analysis of bypass lines efficiency in WWER-440 148 E. Balabanov, A. Ivanovo, A. Sartmadjiev DOEL-4 — loss of external load transient: simulation and analysis 153 E.J. Stubbe, L. Vanhoenacker, P. Moeyart, P. de Schutter, R. Baeyens Analysis of loop asymmetry in Paks nuclear power plant in the event of a cold leg break 169 /. Tôth, L. Perneczky Licensing analysis of steam generator tube plugging: influence on LB-LOCA 180 A. Stritar, B. Mavko Important conclusions from intermediate cold leg LOCA analysis of WWER 440 with RELAP4/MOD6 and SLAP 187 J. Misâk, Z. Bazsô, E. Vaclav Siemens UB KWU-Code package for severe accidents 195 P. Gast A suite of codes for nuclear power plant design safety analysis 205 Yu.D. Baranaev, A.N. Viktorov, A. P. Suvorov ANNEX 1: LIST OF PAPERS PRESENTED AT THE MEETING 209 List of Participants 210 X SUMMARY OF DISCUSSIONS The participants of the Technical Committee/Workshop on Computer Aided Safety Analysis met in the final session and agreed upon the following conclusions: The Programme on Computer-Aided Safety Analysis, run by the IAEA since 1982, has been very fruitful until now. Technical Committee meetings are a good opportunity for the exchange of information at 1.5 to 2 years' intervals. In order to improve the exchange of information a computerized bulletin board system in the field of nuclear safety should be promoted. The system should be established in one of the Member States and could be open and accessible via digital network or telephone lines. That would provide means for very fast information exchange between users on different problems of safety analysis. In the course of time, the collected material would become a valuable source of guidelines for users. For further assessment of safety analysis codes a third standard problem exercise based on the PMK-NVH test facility with a leak from primary to secondary side of a steam generator should be organized. - Member States are encouraged to participate in standard problems, since such problems are the best training for safety analyses. The exchange of information related to separate effect tests and standard problem exercises should be further promoted. Results of some severe accident experiments (e.g. ACE, LACE, fuel behaviour) performed in different countries should be made available to Member States for the validation of severe accident evaluation codes. A meeting on computer codes for radiological consequence analysis, should be organized in the future. Computer codes using trajectory type models for radiological consequence assessment (e.g. TRADOS, CRACHEAT) should be implemented at the IAEA computer and made available to Member States. Experience gathered by Member States participating in the Regional Programme could be disseminated to other Member States by accepting trainees from these countries. In the future it is desirable that both the DBA and the severe accident groups prepare guidelines for using the RELAP5/MOD2 and STCP codes. The guidelines and recommendations from OECD international standard problems should be disseminated among all participants. Guidelines for the training of code users should be developed. Guidelines for QA and QC on use of computer codes for safety analyses should be developed. The next TC meeting should include topics on uncertainty analysis for best estimate codes. Member States are encouraged to start with the activity of uncertainty analysis in the field of nuclear safety. The possibility of including analytical tools for structural analysis in the IAEA's future activities on computer aided safety analysis should be investigated. Specific Conclusions Related to IAEA Programmes on WWER Type Reactors Participants from countries constructing and operating WWER units consider a supporting role of the IAEA as very valuable in the past and of great importance in i^he future for their effort to analyse and improve NPP safety. Substantial progress has been achieved in the field of codes assessment and a wide spectrum of accidents has been analysed. Coordinated 8 activity of participants, consultants and observers within the framework of the IAEA WWER oriented regional projects provided a very good basis for obtaining positive results. For further progress in computer-aided safety analysis and its application for safety of VVER units, the Agency's support is considered to be of great value in the following areas: 1. Analysis of operational transients and accidents within design basis Continuation of WER-440 DBA analysis is of common interest. Several new problems have been recognized in previous calculations which have to be analysed by a more sophisticated approach, such as long-term core cooling by low-pressure injection system, impact of the primary loops asymmetry on core cooling and on overall system behaviour, importance of the secondary side cooling modes for accident mitigation.