LAPPEENRANNAN TEKNILLINEN KORKEAKOULU LAPPEENRANTA UNIVERSITY OF TECHNOLOGY TIETEELLISIA JULKAISUJA RESEARCH PAPERS 67 FOURTH INTERNATIONAL SEMINAR ON HORIZONTAL STEAM GENERATORS LAPPEENRANTA 1997 LTKK-TJ-6} F 980002 LAPPEENRANNAN TEKNILLINEN KORKEAKOULU UDK 621.1 LAPPEENRANTA UNIVERSITY OF TECHNOLOGY 621.039 621.311.25 TIETEELLISIA JULKAISUJA RESEARCH PAPERS 67 FOURTH INTERNATIONAL SEMINAR ON HORIZONTAL STEAM GENERATORS LAPPEENRANTA 1997 ISBN 951-764-189-3 ISSN 0356-8210 FOURTH INTERNATIONAL SEMINAR ON HORIZONTAL STEAM GENERATORS 11-13 March 1997, Lappeenranta, Finland LTKK GROUP 1 FOURTH INTERNATIONAL SEMINAR ON HORIZONTAL STEAM GENERATORS 11-13 March 1997, Lappeenranta, Finland PREFACE A series of International Seminars of Horizontal Steam Generator Modelling were initiated by Finnish nuclear organisations a few years ago. Three seminars have been arranged in March 1991, September 1992 and October 1994 in Lappeenranta, Finland. Improvement in understanding of realistic thermal hydraulic behaviour of the horizontal steam generators when performing safety analyses for WER reactors has been a general objective. The initiated international cooperation has proven to be effective in collecting existing experimental and theoretical knowledge of the behaviour of horizontal steam generators under normal operation, transient and accident conditions. The first two seminars concentrated on thermal hydraulic experiments and analytical modelling of the flow behaviour both in the primary side and in the secondary side. New experimental results, comparisons of existing experimental facilities and approaches to calculational modelling were presented. The scope of the third seminar was enwidened to structural and aging issues. It turned out to be very beneficial to bring structural and thermal hydraulic experts together and thus decrease the difficulties in governing the interface of these areas. It was agreed to include the same subjects to the fourth seminar. Consequently, overall objectives for the fourth seminar were set as • to enhance understanding of horizontal SG behaviour during normal operating and accidental conditions, • to provide forum for discussion among the experts, • to collect new experimental and theoretical results, and • thus enhance safety and economy of WER operation. The fourth seminar consisted of six sessions. The topics were thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the WER safety technology. As in the previous seminars, the organisers were IVO Power Engineering Ltd, Lappeenranta University of Technology (LTKK) and VTT Energy. There were 70 participants in total. They game from 10 countries and 25 papers were presented. The participants represented designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organisations, universities and regulatory authorities. Session I dealt with thermal hydraulic experiments. New results were available from the Finnish PACTEL facility concerning heat transfer degradation and flow distributions during boil-off under natural circulation conditions. Direct measurements of water inventory of the WER-440 steam generator in operation (measured at Rovno Unit 1) were discussed by OKB Gidropress. Thermal hydraulic experiments were presented by Mitsubishi Heavy Industry on the flow behaviour of the secondary side of the horizontal steam generator designed for the passive next generation PWR concept. Influence of dissolved nitrogen in the ECCS accumulator water on the steam generator heat transfer was discussed based on the ii experiments by OKB Gidropress. Finally, the sixth paper of the session introduced the results from experiments in the German HORUS-II facility. Session II consisted of various papers on modelling the horizontal steam generators with thermal hydraulic system codes and their validation against experiments. Coolant flow distribution in the steam generator primary side was also discussed. Session HI started with papers on mechanical integrity aspects of the primary collectors. The significance of temperature stratification in the collectors under natural circulation conditions was discussed and scoping experiments were presented. Session IV dealt with the problem of the feedwater distributor experiencing severe erosion- corrosion in the WER-440 steam generators. Two principally different designs have been applied to replace the eroded pipe sections: one by Gidropress and its modification for Loviisa, and the other by Vitkovice. The first two papers presented the experiments on condensation driven water hammers of the Loviisa designs, and the other papers discussed operating experience and effects on flow distributions of the latter design. Session V was dedicated to the aspects of primary-to-secondary (PRISE) leakage accidents. Plugging criteria and integrity assessment of the heat transfer tubes were discussed by the first two papers. And there was a presentation of thermal hydraulic analyses to support development of the PRISE management concepts. Final Session VI was devoted for new developments in the VVER safety technology. The first paper of the session presented the design and construction status of the large scale KMS facility that is an integral facility to model WER-640 plant concept with passive safety systems. The KMS facility has a volume scaling ratio of 1:27 and it includes the integrated primary circuit with containment. It is being constructed by NITI Institute at Sosnovy Bor near to St. Petersburg, Russia. There was a presentation of the modernisation and power upgrading project of the Loviisa WER-440 Plant. Finally, mechanical component developments of horizontal steam generators in the Czech Republic were presented. Final discussion of the seminar started with a proposal by Dr. Trunov of OKB Gidropress concerning continuation of the common code validation excercises. After obtaining new data on the secondary side water inventory a common calculational excercise could be arranged and every participant would calculate by applying various codes the secondary side water inventory e g. on power levels 0%, 40%, 60%, 80% and 100% The proposal was well taken. Prof. Blagovechtchenski of St.Petersburg State Technical University proposed that cooperative experimental program of his university, Kalinin NPP, LTKK and VTT at Lappeenranta should be supported. Temperature stratifications make an important input from thermal hydraulics to structural integrity assessments of primary components including steam generators. There was common agreement among participants that more papers from the plant operators particularly on the operating experience should be emphasized for future seminars. Dr. Hyvarinen felt that these seminars serve as an excellent forum from the regulator's viewpoint. Organizers should encourage more regulatory authorities to participate and focus even more on operational experience. Ill It was felt that the next seminar should be organised in the time frame of two to three years. It was emphasized that communication between thermal hydraulic and structural and material experts should be sought even more strongly. Also various stratification phenomena and their significance for various plant operations modes and for plant aging should be further studied. The Finnish organizers volunteered to continue as organizers and they also continue to seek for support from international organisations for the arrangements of the next seminar and proposed tentatively to have the next seminar in Lappeenranta in 1999. Harri Tuomisto, NO Heikki Purhonen, VTT Virpi Kouhia, LTKK IV FOURTH INTERNATIONAL SEMINAR ON HORIZONTAL STEAM GENERATORS 11 - 13 March 1997, Lappeenranta, Finland PROGRAMME Tuesday, 11 March 1997 8:30 Registration 9:00 Opening of the Seminar 9:15 Aim and Programme of the Seminar Dr. Harri Tuomisto, IVO Power Engineering Session I THERMAL-HYDRAULIC EXPERIENTS ON HORIZONTAL STEAM GENERATORS Chair: Dr. N. Trunov, OKB Gidropress, Russia Co-Chair: Prof. H. Kalli, LTKK, Finland 9:30 J. Hyvarinen, J. Kouhia: Experimental Verification of the Horizontal Steam Generator Boil-Off Heat Transfer Degradation at Natural Circulation. 10:00 G.A. Tamkov, N.B Trunov, B.N. Dranchenko, W.W. Kamiagin: Direct measurements of water inventory of steam generator PGV-213 in operation. 10:30 Coffee break 11:00 K. Sakata, Y. Nakamura, N. Nakamori, T. Mizutani, S. Uwagawa, I. Saito, T. Tsuyoshi: Advanced Technologies on Steam generators - Study on Thermal- Hydraulic Behavior of Horizontal Steam Generators. 11:30 S.A. Logvinov, Yu.K. Sitnik:Study of Steam Condensation in SG Tubes with Large amount of Nitrogen to be Accumulated. 12:00 S. Alt, W. Lischke: Experiments with the HORUS-II Test Facility 12:30 Discussion on Session I. 13:00 Lunch V Session II THERMAL HYDRAULIC ANALYSES OF HORIZONTAL STEAM GENERATORS Chair: Mr. P. Matejovic, VUJE, Slovakia Co-Chair: Mr. J. Miettinen, VTT Energy, Finland 14:30 F. D’Auria, M. Frogheri, G.M. Galassi: Modelling of WWER-1000 Steam Generators by Relap5/Mod 3.2. Code. 15:00 L. Pemeczky: Possible Thermal Shock Events During Large Primary to Secondary Leakage. 15:30 Coffee Break 16:00 N. Agafonova, J. Banati: The Evaluation of Validity of the RELAP5/MOD3 Flow Regime Map for Horizontal Small Diameter Tubes at Low Pressures. 16:30 A. Blagovechtchenski, V. Leontieva A. Mitrioukhin,: Coolant Rate Distribution in Horizontal Steam Generator Tubes under