N FUEL CHEMISTRY DIVISION ANNUAL PROGRESS REPORT for 1988 S. Vaidyanathan
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2-o3 BARC/1991/P/002 00 > n o o to FUEL CHEMISTRY DIVISION ANNUAL PROGRESS REPORT FOR 1988 S. Vaidyanathan 1991 GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION o o U a: < CD FUEL CHEMISTRY DIVISION ANNUAL PROGRESS REPORT FOR 1908 EdiLecl by S. VaidyanaLhan BHADHA ATOMIC RLSLAROI CLN7KI HOMHAY, INDIA 199 I BARC/1991/P/002 BIBLIOGRAPHIC DESCRIPTION SHEET FOR TECHNICAL REPORT (as per IS : 9400 - 1980) 01 Security classification : Uncl assi-f ied 02 Distribution : External 03 Report status : New 04 Series : BARC External 05 Report type : Progress Report 06 Report ND. : BARC/1991/P/002 07 Part No. or Volume No. : 08 Contract No. ; 10 Title and subtitle : Fuel Chemistry Division : annual progress report for 19BB 11 Collation : 158 p., 61 tabs., 13 figs. 13 Project No. : 20 Personal author(s) : S. Vaidyanathan <ed.) 21 Affiliation Df author(s) :Fuel Chemistry Division , Bhabha Atomic Research Centre, Bombay 22 Corporate author(s) : Bhabha Atomic Research Centre, Bombay - 400 0B5 23 Originating unit : Fuel Chemistry Division, BARC, BDHIIJU 24 Sponsor(s) Name ; Department of Atomic Energy Type : Government 30 Date of submission : July 1991 31 Publication/Issue date : August 1991 Contd... <i i) (ii) 40 Publisher/Distributor : Head, Library and Information Division, Bhabha Atomic Research Centre, Bombay 42 Form of distribution : Hard Copy 50 Language of text : Engli sh 51 Language of summary : English 52 No. of references : 53 Gives data on : 60 Abstract : The progress report gives the brief descriptions of various activities of the Fuel Chemistry Division of Bhabha Atomic Research Centre, Bombay for the year 1988. The descriptions of activities arm arranged under the headings :Fuel Development Chemistry, Chemistry of Actinides, Quality Control of Fuel, and Studies related to Nuclear Material Accounting. At the end of report, a list of publications published in journals and papers presented at various conferences/symposia during 1988 is given. 73 Keywords/Descriptors : PROGRESS REPORT; RESEARCH PROGRAMS; MICRDSPHERES; THORIUM OXIDES; URANIUM OXIDES; PLUTONIUM; URANIUM; SOLVENT EXTRACTION; ION EXCHANGE MATERIALS; RESINS; QUANTITATIVE CHEMICAL ANALYSIS; NUCLEAR FUELS; ACCOUNTNG; QUALITY CONTROL; BARC; CALIBRATION STANDARDS 71 Class No. : INIS Subject Category : B16.10 99 Supplementary elements : The previous progress report was published as BARC-1516 covering the period 19B7 ( i ) PREFACE The activities of the Fuel Chemistry Division during 1988 are presented in this Annual Report in four sections. The first section, Fuel Development Chemistry, deals with sol-gel processes for the synthesis of microspheres such as DC, (U,Ce)C and ThO2 and non-nuclear ceramics. Also included in this section are the measurement of some of the thermodynamic parameters of materials like nickel telluride, sodium zirconate, caesium chromate, caesium molybdate etc. which are likely to be encountered in operating reactors. The second section, Chemistry of Actinides, deals with i,he solid state, sol'ition and process chemistry of actinides. Solid state reactions and phase studies are the areas of work covered in solid state chemistry. In solution chemistry, solvent- extraction studies with Di-2 ethylhexyl phosphoric acid (D2EHPA), long chain secondary amine Amtaerlite LA-1 and MOFPA and ion-exchange studies from mixed solvent media have been covered. Studies in Process Chemistry include evaluation of different anion exchange resins for plutonium processing, recovery of U-233 from phosphate containing aqueous waste, recovery and purification of plutonium from fuel fabrication scrap etc. i i ) The third section, Chemical Quality Control of Nuclear Fuels deals with analytical methods, primary ciemica) standards and analytical services. Analytical methods cover the developmental work on electrochemical, titrimetric and mass spectrometric methods for the chemical quality control of nuclear materials. Preliminary studies on the preparation and characterisation of primary chemical assay standards for uranium and plutonium are reported. In the fourth section, Nuclear Materials Account ing,an overview of NUMAC database maintained for the nuclear materials accounting ir. all the DAE Facilities has been given. The report also includes a list of papers published in Journals and presented at various Con f er ences -'Sy rr.pos i a.. The Editor expresses his sincere thanks to Dr. D.D.Sood, Head, Fuel Chemistry Division for his valuable suggestions in the preparation and organisation of this report. He also highly appreciates the cooperation and help rendered by Sri Satya Jyothi in compilation of this report. ( ii i CONTENTS PREFACE ( i ) 1. FUEL DEVELOPMENT CHEMISTRY 1 1.1 Soi-Gel Process Development. 1 1.2 High Temperature Thermodynamics. 20 2. CHEMISTRY OF ACT IN IDES 35 2.1 Solid State Chemistry. 35 2.2 Solution Chemistry. 47 2.3 Process Chemistry. 76 3. CHEMICAL QUALITY CONTROL OF FUELS 99 3.1 Analytical Methods. 99 3.2 Primary Chemical Assay Standards. 131 3.3 Analytical Services. 139 4. NUCLEAR MATERIALS ACCOUNTING 142 5. PUBLICATIONS 146 FUEL DEVELOPMENT CHEMISTRY 1. 1 SOL-GEL PROCESS DEVELOPMENT 1.1.1 SYNTHESIS OF URANIUM MONOCARBIDE MICROSPHERES BY SOL-GEL PROCESS. S.K. Mukerjee, J.V.Dehadraya, Y.R.Bamankar, V.N.Vaidya and D.D. Sood. Introduction The present trend in fast reactors towards higher operational temperatures, higher linear power rating, and higher breeding ratio points towards the possible use of carbide as nuclear fuel for future systems. Presently carbothermic reduction of UO2 + PuO2 powders followed by grinding and pe11etization of carbide powders is the established route for mixed carbide fuel fabrication. Sol-ge! method of preparation of carbides has several advantages over the conventional pellet route; as it uses a minimum number of steps with carbothermic reduction itself leading to dense particles and no grinding or milling of reactive and pyrophoric powders is required. Several reports^"4-' have been written concerning the carbo- thermic reduction of carbon containing oxide gel particles to carbide. Al1 these reports deal with the reduction carried out in two steps, first the reduction of UO3 to UO2 by hydrogen followed by carbotherinic reduction. This was necessary as the C/M ratio, approximately 3.5, required for direct carbothermic reduction of the particles could not be obtained because of difficulties in dispersion of large amounts of carbon. The hydrogen reduction of UO3 itself is complicated due to side reaction of hydrogen and moisture with carbon and thus fixing of the carbide s to i ch i oine try becomes difficult. The present work overcomes this problem as sufficient quantity of carbon can be dispersed in the gel particles using proper metai ion concentration by the use of gelation field diagram^'' and C/M ratio around 3.5 can be obtained easily in the gel par t ic1es. Ex per i menta1 Internal gelation process and the gelation assembly used for the preparation of gel particles have been described elsewhere^-', Maximum C/M ratio obtainable with standard feed composition is 3.3 as uranium molarity in such a solution is 1.2M and (HMTA, urea)/uranium mole ratio is 1.4. Thus in the present investigations the uranium molarity in the feed solutions was lowered. Uranyl nitrate solution (3M) was mixed with a scliitior, of HMTA and urea containing finely dispersed carbon powder (United KAF) in cold condition (0°C) to obtain feed solution 1.1M in uranium and having (HMTA, ur ea ) / u ran i. urn mole ratio of 1.5. The droplets of this solution were contacted with hot silicone oil to obtain UO3 gel partic! ','F with homogeneously dispersed carbon. Total 9 batches were prepared and C/M mole ratio in the feed was varied between 3.45 to 3.50. The gel particles were washed, dried ami heated in argon upto 300°C to remove moisture, ammonia and residua! gelation agents. Experiments on heat treatment were done on 50 g per bai-rh scale in a tantalum carbide crucible. Heating was carried out in high temperature high vacuum tungsten heater furnace. Initially UO3 was reduced to UUo by reaction at 700°C. Carbothermic reduction of UO2 was initiated around 1200° C and soak time at various temperatures varied from 2 to 10 hrs. Sintering was done for 2 hours at 1700°C in argon. The product was analysed chemically for oxygen uranium and carbon. X-ray diffraction analysis was done to identify the phases present. The density was determined by stereo pycnometer. Results and Discussion The results are summarised in Table 1. In all cases silvery shining and crack free microspheres were obtained. Reduction and sintering carried out at lower temperature resulted in high oxygen content. Thi? could have resulted because of slow rate of reaction at low temperatures as the particles sinter and close the pores and do not allow the reaction to go to completion. Similar results were obtained when the reaction was carried out at high temperature as the sintering became faster than the reduction. A compromise was made by increasing the temperature from 1300 to 1500°C at a very slow rate. This helped the reaction to proceed at a steady rate and the product contained around 1000 ppm of oxygen. Further work is in progress to lower oxygen content. This work has shown the possibility of using direct carbothermic reduction of gel particles to obtain UC microspheres using internal gelation process without resorting to a hydrogen reduction step. References 1. J.I. Federer and V.J. Tenner, ORNUTM-6089119781. 2. K. Bischoff, V. Scherer and H. Schumacher, Symposium on Sol-Gel Processes and Reactor Fuel Cycl e, CONF-700502, U5M 1 970 ) 3. K.Bischoff, M.H. Lloyd and H, Schumacher, So I-Gel Processes for Fuel Fabrication 1AEA-161, International Atomic Energy Agency, Vienna, 95 (1974i 4. A.Facchini and P. Gerontopulos, Sol-Gel Processes for Fuel Fabrication, IAEA-161, Internationa I Atomic Energy Agency,Vienna,95.11974 ). 5. V.N. Vaidya, S.K.