IWGGCR/2 I INTERNATIONAL WORKING GROUP on GAS-COOLED REACTORS
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vv International Atomic Energy Agency IWGGCR/2 i INTERNATIONAL WORKING GROUP ON GAS-COOLED REACTORS Specialists Meeting on Coolant Chemistry, Plate-out and Decontamination in Gas-cooled Reactors Juelich, Federal Republic of Germany 2-4 December 1980 SUMMARY REPORT INTERNATIONAL ATOMIC ENERGY AGENCY Specialists' Meeting on Coolant Chemistry, Plate-out and Decontamination in Gas-cooled Reactors Juelich, Federal Republic of Germany 2-4 December 1980 Chairman: C.-B. von der Decken Kernforschungsanlage Juelich GmbH. Institut fuer Reaktorbauelemente Juelich, Federal Republic of Germany Scientific Secretary: J. Kupitz International Atomic Energy Agency Vienna, Austria SUMMARY REPORT Printed by the IAEA in Austria May 1981 CONTENTS 1. INTRODUCTION 5 2. SUMMARY AND CONCLUSIONS 2A. Fission Product Plnte-out 1 & 2 5 2П. Decontamination of Activity 6 2C. Coolant Chemistry 6 21). Discussions, Conclusions and Recommendations 7 3. CONTRIBUTIONS In-pile helium loop "Comédie" 8 J J. Abnssin, R.J. Blanchard, J. Gentil Out-ot'-pile helium loop for liftoff experiments 17 R.J. Blanchard, A. Bros, J. Gentil Experimental facilities for plate-out investigations and future work 26 K. Muenchow, II. Dederichs, N. Iniotakis, B. Sackmann Results from plate-out investigations 35 N. Iniotakis, J. Malinowaki, H. Gottaut, K. Muenchow F.P. plate-out study using in-pile loop OGL-1 44 0. Baba Fission product behavior in the peach bottom and Fort St. Vrain HTGRs 49 D.L. Hanson, N.L. Baldwin, D.E. Strong Iodine sorption and desorption from low-alloy steel. and graphite 55 R.P. Wichner, M.F. Osborne, R.A. Lorenz, R.B. Briggs Remarks on possibilities and limitations of theoretical approach to plate-out problems 64 E. Obryk Fission product behaviour in the primary circuit of an HTR 68 C.-B. von der Decken, N. Iniotakis Derivation of criteria for primary circuit activity in an HTGR 75 S.D. Su, A.W. Barseil The infLucnce of dust on the hazard potential of a depressurization accident of a high temperature reactor 81 N. Iniotakis, C.-B. von der Decken Modelling of plate-out under gas-cooled reactor (GCR), accident conditions 87 A.R. Ta ig Safety research on iodine plate-out during postulated HTGR coie heatup events 94 A.W. Barsell, O.P. Chawla, CG. Hoot Plate-out measurements and decontamination of a component of the AVR reactor at Juelich 99 J. Hanulik, H. Schmied, J. Wahl Evaluation of n decontamination model 107 O.W.T. Rippin, Л. Hanul.ik,^. Schenker, G. Ullrich Decontamination and high temperature materials 114 E. Schenker, G. Ullrich, .1. Ilanulik, W.B. Waeber, K.M. Wiedemann Maintenance concept of the gas turbine in a 1640 MW direct cycle HTR 11H II. Schmied, H. Karaus, К. Rocllig, E. Schenker Coolant Chemistry of the advanced carbon dioxide cooled reactor .... 125 R.L. Faircloth, K.S. Norwood, H.A. Prior Primary coolant chemistry of the Peach Bottom and Fort St.Vrain high-temperature gas-cooled reactors 132 11.D. Burnette, N.L. Baldwin Chemical reactions during nuclear drying of the AVR primary circuit following a water ingress 137 U. Nieder, К. Vey Predictions on an HTR coolant composition after operational experience with experimental reactors 144 R. Nieder Tritium behaviour in an HTR-system based on AVR-experience 153 W. Steinwarz, II.D. Roehrig, R. Nieder 4. AGENDA OF THE MEETING 161 5. LIST OF PARTICIPANTS 163 1. INTRODUCTION 2. SUMMARY AND CONCLUSIONS 2A. FISSION PRODUCT PLATE-OUT 1 & 2 The Specialists' Meeting on "Coolant Chemistry, Plate-out and Session chairmen: Decontamination in Gas-cooled Reactors" was held at the Fission product plate out 1: Mr. Blanchard Kernforschungsanlage Juelich GmbH., Juelich, Federal Republic of Germany, 2-U December 1980. The meeting was sponsored by the International Atomic Fission product plate out 2г.. Кг. ВаЪа Energy Agency (IAEA) on the recommendation of the International Working Group on Gas-cooled Reactors (IWGGCR) and was attended by 38 participants and observers from France, Federal Republic of Germany, Italy, Japan, Prediction of distribution of fission products which are deposited Poland, Switzerland, the United Kingdom of Great Britain and Northern on surfaces in primary circuits of gas-cooled reactors depends on îmow— Ireland and the United States of America. ledge of the value of a large number of parameters. These paraceters are being estimated by experiments in various test facilities. The purpose of the meeting was to provide a forum for exchange of information on experimental and theoretical results of fission product Two categories of test—facilities are used: behaviour in primary loops of gas-cooled reeactors in order to provide comprehensive review of the present status and of directions for future — in-pile loops applications and development. — out-of-pile loops The meeting was divided into five sessions: Specimens of irradiated fuel from gas-cooled reactors are used as the source of fission products in the in-pile loops, ue fuel is irradiated A. Fission Product Plate-out I further during the test by neutrons produced in test reactors. In order to B. Fission Product Plate-out II get an appropriate fission product source burnt-up fuel orf in case of C. Decontamination of Activity coated particles, fuel with a certain amount of defect particles is used. D. Coolant Chemistry Fission products are then carried by the heated coolant gas through, the E. Round Table Discussion plate-out section where some deposit on various material samples to be examined later. Subsequently, the gas is filtered, purified ana flows back to the fuel section. During the meeting papers were presented by the participants on behalf of their countries or organizations. Each presentation was In-pile experiments have been performed or are planned in the following followed by an open discussion in the general area covered by the paper. loops: - Saphir (Pégase reactor) CSA, Cadarache, Prance - Comédie (Silo'é reactor) CSA, Grenoble, France - Vampyr I (AVR reactor) KFA, Jülich, Federal Republic of Germany - Vampyr II (AVR reactor) KFA, Jülich, Federal Rerublic of Germany - OGL 1 (JMTR reactor) JAERI, Tokai Mura, Japan. In addition to these in-pile loops, samples of materials that have been loaded with fission products in main circuits of gas-cooled reactors such as in the Dragon Reactor, Peach-Bottom and FSV have been examined. Concerning the out-of—pile loops, single ion sources such as Cesium, Iodine and Silver are used instead of reactor fuel. These loops allow the study of interaction of selected isotopes with various reactor materials. Out-of-pile experiments are performed in, or planned for the followir^ loops: б - Scafex (КРА, Jülich, Federal Republic of Germany) 2B. DECONTAMINATION OF ACTIVITY - Smoc (KFA, Federal Republic of Germany) - Lift-off experiments (CEA, Grenoble, France) - Iodine sorption/desorption test facility (ORNL, Oak Ridge, USA) Session chairman; E. Obryk - Helium loop (EIR, WUrenlingen, Switzerland) Radiation levels caused by fission and activation products deposited in primary circuits of nuclear power plants require decontamination of Experiments are performed under various combinations of several reactor components in order to conduct inspection and repair. The basic parameters such as flow rate, time, temperature, fission product concen concept of decontamination by wet chemical treatment is that the activity tration and composition of coolant gas. near the surface boundary is removed as the surface itself is dissolved away by the decontaminating fluid. Comparison of experimental and theo Results demonstrated that fission product deposition does not only retical results have proved that the extent of penetration of radioactive depend on adsorption and desorption mechanisms at the surface but also on material into the wall material of reactor components can be predicted. irreversible mechanisms such as diffusion into the wall-raaterial. Adsorption Thus, the depth of the surface material to be dissolved can be determined. and desorption are of main importance at lower temperatures than },Q0oC, but Chemical solutions have been developed in order to remove the desired at temperature above 500° diffusion is dominant more and more with increasing surface layer. These substances have been tested successfully on samples temperature and operation time. loaded with fission products and on components of "the Arbeitsgemeinschaft Versuchsreaktor (AVR) in Jülich. Experimental results together with power plant design parameters are the input for computer codes that have been developed for the prediction of The maintenance concepts for the gas "turbine for a 1640 KW direct fission product behaviour. Codes are available in the Federal Republic of cycle HTR were reported and extensively discussed. The maintenance concepts Germany (KFA/IKB), Japan (JAERI), UK (UKAEA) and USA (CAC). foresee minor inspections at two years intervals and zajor inspectiez every six years. The major inspections require disassembling and dismantling of In addition to Iodine the main fission products to be considered are the turbo-machine and the inspection of the individual parts. The "turbo- Ag 110 m, Cs 134, Cs I37 and Ba/La 140. The influence of dust as a transport machine will be transferred by a traction a?chine into a dismantling cell. mechanism for fission products must be taken into account for the prediction The machine wiT.1 be dismantled by remote—handling. For the disassembling of fisBion product plate-out. of the machine blades two variants were reported: — remote controlled disassembly of machine blades — manual disassembly of machine blades with pre—decontamination. After having disassembled the blades they will be decontaminated separately and examined using a special inspection procedure. After having inspected all components of the turbo-machine it will be re—assembled, mounted and connected into the primary circuit. The power plant shut down tine for the major inspection is expected to be ^0-60 days. 2C. COOLANT CHEMISTRY 2D. DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS Session chairman: R. Wichner Session chairman: С. B. von der Decken The operation of the Peach Bottom and Port St.