IAEA-TECDOC-687 Fission and corrosion product behaviour in liquid metal fast breeder reactors (LMFBRs) INTERNATIONAL ATOMIC ENERGY AGENCY The IAEA does not normally maintain stocks of reports in this series. However, microfiche copie f thesso e reportobtainee b n sca d from INIS Clearinghouse International Atomic Energy Agency Wagramerstrasse5 P.O. Box 100 A-1400 Vienna, Austria Orders should be accompanied by prepayment of Austrian Schillings 100,- fore for e chequa th f m th IAEf m o n i o n i r eAo microfiche service coupons orderee whicb y hdma separately fro INIe mth S Clearinghouse. FISSIO CORROSIOD NAN N PRODUCT BEHAVIOUR IN LIQUID METAL FAST BREEDER REACTORS (LMFBRs) IAEA, VIENNA, 1993 IAEA-TECDOC-687 ISSN 1011-4289 Printed by the IAEA in Austria February 1993 FOREWORD In 1969 e Internationath , l Atomic Energy Agency decide o includt d e th e topic of fission and corrosion product behaviour in liquid metal fast breeder reactors (LMFBRs} in its programme of specialists meetings. It was apparent at the time that with the advent of experimental fast reactor systems in the USAe USSRth , ,e Unite Francth d d an eKingdom e expansioth , f supportino n g research programme e fragmenteth d an s d natur f informatioo e n arising from these various activities, it would be beneficial to co-ordinate certain topics at an international level. Suppor thir tfo s approac provides hwa Membey db r States and, against this background e IAEs helth ,Aha d three international specialists meetingse on , Germanyn i o purpose meetinge tw Th provido USSe th .d t i th n f an R s o e wa se a better understanding of the way various radionuclides behave in operating systemo providt d an se guidance safth e r developmenfo e f prototypo t d an e eventually commercial systems o meeT .t these objective e specialistth s s discussed experiment results, reviewed experimental programme identified san d area further fo s r work. e researcth s A h programmes develope d moran de information became available, an introductory review of the topic was published by the IAEA in 1979. Since then the amount of information coming from experimental facilities and operating fast reactors has increased considerably and this document has been written, firstly to keep abreast of current developments and, secondly provido t , presene arte e 'staterecora th th th t a 'f f to e o d time. It is intended that this review will be useful not only to scientists but als thoso ot e concerned with design, day-to-day operatio plantf no , safetd yan decommissioning. Because of this, the review has been widened to include not onl mase yth s transfer behaviou varioue th f ro s radionuclide experimentan si l d operatinan g systems t alse monitorinbu ,th o e variouth f o gs speciese th , methods of measurement and the development of methods to control the buildup of the more important long half-life species in operating plants. e informatioTh reviee n th usebees n wha i dn taken from open literature n sourcethii sd an . contexMichaillsP . Dr t e (Commissaria à l'énergit e atomique, Cadarache, France) has researched existing documents to provide an up-to-date presentation of the behaviour of the various isotopes in LMFBRs. Technical support and assistance with the production of the document has also been provided by Mr. A.W. Thorley, formerly of the UKAEA, Risley. Mr. V. Arkhipov, of the IAEA's Division of Nuclear Power, was responsible for the final drafting of the report. EDITORIAL NOTE In preparing this material press,the International the for staffof Atomic Energy Agency have mounted and paginated the original manuscripts and given some attention to presentation. The views expressed necessarilynot do reflect those governments ofthe Member ofthe Statesor organizations under whose auspices the manuscripts were produced. thisin The bookuse of particular designations countriesof territoriesor does implynot any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities institutions delimitationand the of or theirof boundaries. The mention of specific companies or of their products or brand names does not imply any endorsement recommendationor IAEA. partthe the of on This text was compiled before the recent changes in the former Union of Soviet Socialist Republics. CONTENTS OVERVIEW ................................................................................................... 7 1. INTRODUCTION ...................................................................................... 9 . 2 INTRODUCTORY REMARKS CONCERNING SOURCES, PRODUCTION AND BEHAVIOU VARIOUF RO S RADIONUCLIDES .....................................1 1 . 2.1. Source f radioactivito s y ........................................................................1 1 . 2.2. Production of various isotopes and their behaviour in LMFBRs ....................... 11 BEHAVIOUE TH . 3 ACTIVATIOF RO N PRODUCT LMFBRN SI s ........................7 1 . 3.1. phass Behaviouga e th .................................................................... n i r 7 1 . 3.2. Behaviour in the sodium ........................................................................ 19 4. CONTAMINATION OF LMFBRs BY RADIOACTIVE CORROSION PRODUCTS ... 24 4.1. Level f gammo s a activity induce corrosion di n products ................................4 2 . 4.2. Corrosio f materialno LMFBRn i s s .........................................................5 2 . 4.3. Corrosion equations .............................................................................. 34 4.4. Deposition behaviour of corrosion products — General comments .................... 37 4.5. Experimental results of release and deposition of radioactive corrosion products ..............................................................................0 4 . 4.6. Developmen f release/depositioo t n model r radioactivfo s e corrosion products 8 .....4 . 4.7. Compariso f codno e results with reactor measurements .................................3 5 . 5 FISSION PRODUCT LMFBRN SI s ...............................................................2 6 . 5.1. Formation and release from fuel .............................................................. 62 5.2. Transfer to the sodium .......................................................................... 65 5.3. In-sodium behaviour of fission products ..................................................... 69 5.4. Method r estimatinfo s distributioe gth f fissiono n product fissild an s e material in LMFBRs ........................................................................................ 79 6. THE BEHAVIOUR OF TRITIUM IN LMFBRs ................................................ 84 6.1. Model to describe the distribution of tritium in LFMBRs ............................... 84 6.2. Source processed an s s which affec distributioe th t f tritiuo n LMFBRmn i s .........7 8 . 6.3. Instrumentation use r measurindfo g tritium levels ........................................1 9 . 6.4. In-reactor measurements .......................................................................2 9 . 6.5. Validation of the Kumar model using reactor measurements ............................ 95 7. RADIOACTIVITY LEVELS IN LMFBRs - REACTOR MEASUREMENTS ........... 97 7.1. Reactor measurements — Methods used ..................................................... 97 7.2. Result f reactoo s r measurements .............................................................2 10 . REMOVAE TH . 8 RADIONUCLIDEF LO S FROD COVEE AN MTH S RGA SODIUM COOLANT OF LMFBRs ................................................................ 113 8.1. Removal of radioactive impurities from the cover gas — Methods used on operating reactors ...........................................................................3 11 . e remova8.2Th . f fissioo l activatiod an n n products from sodiu coly mb d trap ..........8 11 . 8.3. Removal by special radionuclide traps — Development and experience .............. 121 . 9 SUMMAR BEHAVIOUE TH MORE F YO TH EF RO IMPORTAN T RADIONUCLIDES IN LMFBRs ................................................................... 131 . AREA10 FURTHER SFO R WORK ..................................................................5 13 . REFERENCES ...............................................................................................7 13 . OVERVIEW The behaviour of radionuclides in sodium loops and reactor systems has been extensively studied thre r o ove pas e o erth ttw decade supporn si f to the safe operation of LMFBRs. The studies, which are reported and discussed in this review, have shown that in common with other reactor designs the production of radionuclides in LMFBRs operating with mixed oxide fuel contained in Type 300 stainless steel cladding is by activation of the cover-gas, the coolant, core components and fission processes in the fuel. The coolant transports radionuclides away frocor e increased mth e an d activity levels can occur in regions such as the cover-gas, the intermediate heat-exchanger pumpsd san . The review indicates that after plant shut-down prior activation of the cover-gas and the sodium coolant should not significantly affect activity level bees sha n onc a alloweN e 2decayo 4dt . Reactor experience indicates that Xe and Kr from tramp fuel or failed pins can be effectively removed by 85 carbon bed delad san y tanks respectively longee th d r, an half-lif n ca r K e be safely vented to atmosphere. Contaminants in the sodium such as Zn, are know preseno nt t problems however chemicae th d ,an l behaviou thif