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( * Z * * * A-" & awa - 3/4-7 MASTER PILOT PLANT PREPARATION OF U”-mo, SHARDS * * sol-GH METHOD, preparatory To PRODUCING POWDERS FOR WIBRATORY PACKING INTO FUEL TUBES" By C. C. Haws, Jr. Pilot Plant Section Chemical Technology Division Oak Ridge National Laboratory Focsimile Price #: .* /Y "…#. $_ Avoilable from the | Office of Technical Services Deportment of Commerce Woshington 25, D. C. Presented at the Powder £illed U02 Symposium _2 * held in Worcester, Mass: usetts, *mms November 5-6, 1963, L. : G A l NOW D C : This report wee prepared ee en erroma el Goveranset agreesored werú. Motest as t’arts& •=. * be erasese restslosé Ma Ble regart. •e "at Če use :::::::::: Q £--------------- [rese W* -: UQ * Ae used in Qin where, *gorase setts on bastall of the Commiesbea *:::: pterse er esnaretter el úe Commisstaa. •e easterse of esta rearrettas. : (*@geroe. each sapleyse as centrerest of the C*seesa. ::::::: Cleese"se. e. prwatóse erroes ta. Way Bader-attee pureenst *Jiey w". ©e Createstea. ©e ble wagtegases wheerb centrerter, + Research sponsored by the U. S. Atomic Energy Commission under COn tract with the Union Carbide Corporation. As a ****A*.*.*.* - ... . *** *******, *, *... . . . * ...'... al * I w" ** m". """Twi "rrºw way Imm. “vir arr warml ... "w ** | * * * *"...' ' l : CONTENTS ABSTRACT INTRODUCTION NESCRIPTION OF THE KILOROD FACILITY 3. l Radiation -Control Factors 3.2 Process Flowsheet 3.2. l Floor Plan of the Sol-Gel and Rod Fabrication Units 3.2.2 Location of Feed-Preparation Operations DESCRIPTION OF THE EQUIPMENT AND THE OPERATING PROCEDURE l, . 1 Preparation of Feed Materials l; .l.l. Thorium Oxide Feed Preparation l, . l.2 Powder Blending l, .l. 3 Purification of U233 Feed Solution l, .2 Preparation of Sol-Gel Product l, .2.1 Flowsheet Conditions l; .2.2 Procedure l; .2.3 Descriptions of Sol-Gel Process Equipment RESULTS OF SOL-GEL OPERATIONS KILOROD PROGRAM RADIATION DATA FUTURE SOL-GEL WORK CONCLUSIONS ACKNOWLEDGEMENTS . | lO lO l2 l2 l3 15 2l 21; 26 3l 3l - **:::: l, ABSTRACT Progress for the first five months of sol-gel pilot plant operation is reported. During this period 500 kg of 3% u”02-91% Thoe (solid solution) was prepared in the form of shards that had a density 99% of the theoretical. A sustained throughput of 10 kg/day was demonstrated, and all product met expected chemical standards. The sol-gel process is a unique method for preparing feed materials suitable for vibratory-compaction fabrication of reactor fuel elements: *\ The process upon which the present work was done consisted in the follow- © ing steps: l. Preparation of a Thoe powder suitable for dispersion in weak nitric acid. The powder is prepared by hydrothermal denitration of thorium nitrate crystals at 500°C. 2. Removal of U” solvent extraction. This operation permits use of the lightly shielded 233 daughter products from U feed stocks by glove-box type facility built for this work. 3. Blending at 80°C or the Thoe powder and U l and 2 to form a stable sol. ls. Drying of the sol to a gel state at 80°C. 5. Caleination and reduction of the dried gel at ll30°C under an argon-hydrogen atmosphere to produce shards which are then transferred to the rod-loading facility. 100 x U233 The J/Th ratio: defined as , was controlled to within U233 + Th 3.00 + 0.05 following the start-up period. Gas-release values to 1200°C WeI'e s O.Q3 stol. cc/gm for the calcined product, and < O.5 cc/gm for the 233 solution from steps crushed-sized powder as loaded into the fuel elements. The principal gases released by the product were H2, CO2, water, and CO(or N2). Exposure of workers to radiation was satisfactorily low. Hand- forearm doses did not exceed 200 millirems/wk as contrasted to a 1500 per week permiscible doss. Pilot plant operation will continue until 1000 kg of product has been produced. *Also called weight percent t;233. r * l * ***.*.*.*.*************** **, *, *, *, *.*.*.*..., , , , , a , , , , , , , , , , , , , , , i. ; : ..]." ' ' '... . . . . . . * * *S's">Sewers":"S *~~r" - " "r- N*W*. l * " " " ' " ' " : ""-8 as..?'...' ... . . . . . . . . . ..., '" - " . . . .” . . . . . . . . . . . . ." . . . . . * \ - ..", ... . * , r r # * ' " '''''', * * * * * '*''': *, ' , "...''' ' ', ''''', ''x'': ' , , " " ' ". . . .'' "; , . . . ' ' ' ', ...,' . ". . " * * * * - ' ' " • , - a. ** £% ". !' . . ". "1. v. * *, * ... \ . . . ." l. * - " . . . - - 'i ** . , ", , , - - 2, INTRODUCTION The sol-gel process is a unique recent advancement in the preparation of ceramic nuclear fuels. This process yields a fragmentary, or shard- type, product having a density of 99% of theoretical. These chards are an ideal starting material for fuel element fabrication by Vibratory complac - tion . Since June, a pilot plant comprised of a sol-gel-process, complex and a vibratory -compaction rod-loading unit has prepared 10 kg per day of 3% u”0,-- 97% Thoe. This pilot plant was built to prepare 1000 fuel rods for the Brookhaven National Laboratory; hence, it is called the Kilorod Facility. Basically the operation of the pilot plant includes preparing a Thoe powder by hydrothermal denitration of thorium nitrate 233 solution crystals, blending of a sol using the Thoe powder and a U which has been purifed by solvent extraction, drying of the sol to a gel, and calcination-reduction of the gel to the glass-like product (or shards). To date, about 500 kg of solids has been produced, representing about half of the program commitment. All material produced has met specifications and has been loaded into reactor fuel tubes. This paper will first describe briefly the entire Kilorod Facility i and discuss in detail only the sol-gel portion of the operation. The next speaker will discuss the operation of the fuel-element fabrication portion of the Facility. After the Kilorod Facility has been described, the sol- gel process will be discussed, and the following topics will be covered: l, the source and importance of radiation to the design and operation of the process, 2. the floor plan of the facility, 3. the procedure and the sol-gel equipment, and l, accumulated process control and personnel exposure data. At the conclusion, the applicability of the sol-gel process to the preparation of a variety of ceramic nuclear materials will be shown. 3. DESCRIPTION OF THE KILOROD FACILITY 3.l Radiation-Control Factors Several factors concerning personnel protection were considered in selecting a design for the Kilorod Facility. The containment requirements for U233 are essentially the same as for plutonium, since U233 also emits alpha particles at a high rate. Additionally, U232 233, and 38 ppm is present in the U233 used for the 232 is always produced in the preparation of U Kilorod feed (see Fig. 1). The gamma-emitting daughters of U a penetrating radiation hazard. The daughters can be removed by Golvent present extraction, but grow back in; thus, the gamma emission rate increases rapidly from the time of purification, and a time limit is imposed upon processing. A weekly dose of 1500 millirems to the hands and arms is * permitted, much higher than can be tolerated (100 millirems) for whole- body exposures." Models incorporating the above design criteria were studied, and the following design was selected. The resulting facility is a shielded glove- box type of operation. In this type of operation, higher doses are taken by intent on the hands and arms than on the body. A 20-day time limita- tion from solvent extraction to preparation of the last sol-gel batch of a given processing campaign appeared reasonable. Experience has shown that this design and this time limitation were conservative, as will be shown. 3.2 Process Flowsheet The flowsheet of the entire Kilorod Facility is shown in Fig. 2. To simplify discussion, the facility will be visualized as being composed of three parts, as shown on the flowsheet. These are: l, feed preparation - solvent extraction and hydrothermal denitra- tion, 2. the sol-gel process - preparation of the sintered solids, and 3. the rod-fabrication operation - powder preparation and rod fabrication . As mentioned above, only the first two subjects are covered in this talk. 3.2.1 Floor Plali of the Sol-Gel and Rod-Fabrication Units The equipment for the sol-gel process and rod fabrication was in- t *|w stalled in one cell at the Laboratory. Figure 3 is an artist's conception of the portion of the facility within this cell. Note that the processing Health Physics Manual, Procedures and Practices for Radiation, Protection, Oak Ridge National Laboratory, Procedure 20. --- * #'''f'' are 232'' (n,2n) 233 *U*IN RECYCLE FUEL U t U ~ 10% FROM U239 £ . s a 74 y , 232 £ nérQy : (n, ), | Pb212 | O.25o | P223. Th228 O.72O O. : O.83O | O. 19 £25h , I.O3 OO6 23| Bi212 | 1.34 |OO5 Th” 6.13 h a 1.9 y | 6 || || OO7 (n,2n) | 8 || | OO7 | 2.2 OO35 O.5|O | O.25 Th232 Ac228 Ro224 T1208 O,582 O.80 O859 2.62 a 1.39x10%| /867 y a 3.64 d | | | S | - 64% | G 54.5 s a 3.04 x 10's t * (, . / () Po216 Bi212 Pb206 ! i 6O.6 m (stable) w © . '8 36% 3.1 m a O. 1588 |O.6 8 h | | Pb212 T1208 Fig. 1. Decay Chain and Gamma Activity in Tho2-U°3302 Fuels. *||- -- |:#A , ,|t UNCLASSIFIED THORIUM ORNL-Dw9. 63-62 NITRAT "l HYDROTHERMAL DENITRATOR SOL-GEL FUEL ROD AGED PROCESS FABRICATION U233 m | | - FUEL U233 SOLVENT '': RODS EXTRACTION SOLUTION !. Q FUEL ROD Las DECAY PRODUCTS CARRIER Fig. 2. Kilorod Facility Flowsheet. ... • *** * * ~ -. • * * * - * * * * * = - * ... • * * * * ~. * * * * - * * * ~ . * * * * * * * * * * * * * * * PERSONNEL SHIELD 4-1/2 (IP in. STEEL ------" ... " SOI.-GEL ------" " £ . . . . | s OXIDE *... . . . . . |PREPARATION LEVEL CELL WAll - 5ft concRETE ** A. * ... / PRIMARY * I_* CONTAINMENT -- - (SEALED) L- t a , * **, . 8-1/2-in. BARYTES CONCRETE *-RS SECOND LEVE!. EQUIPMENT |MAINTENANCE *::= " *=T: "..... * ** , , * , & *. * ".” . . ‘. . . .''. ". CONDITIONING SHAFT servicing Ports FIRST LEVEL ROD FABRICATION: VIBRATORY COMPACTION WELDING CLEANING INSPECTION The process flow begins at Fig. 3. Kilorod Solids Preparation and Rod Fabrication Facility. the top left with sol blending, flows to the right where the solids are fired, passes down the vertical shaft as the powder is prepared, and across the bottom as the rods are loaded and tested. #######436.4-iss." cubicles are built in a three-level arrangement within the outer (concrete) walls of the cell. All process cubicles are lined with 1/8-in. -thick mild steel, for alpha particle containment. Shielding of workers from gamma rays is provided by either 4-1/2 in. of steel or by 8 in. of dry, stacked barytes block. The sol-gel cubicle (about 7 ft x 10 ft) is located on the third floor, and the rod-fabrication equipment extends from just below the third floor down to and across the first floor. 3.2.2 Location of Feed-Preparation Operations The solvent extraction plant is located in three adjoining cells within this same building, while denitration is carried out in a separate building. l!. DESCRIPTION OF THE EQUIPMENT AND THE OPERATING PROCEDURE l; .l Preparation of Feed Materials In essence, feed material preparation consists of two processes: Thoe powder is prepared by the hydrothermal denitration of thorium nitrate crystals, and U233 as a nitrate solution is freed by solvent extraction of U232 daughter products. * 1:1 Thorium oxide Feed Preparation: The First step Toward Preparing Mixed oxides (Thoz-UO2) by the Sol-Gel Process The thoritum oxide feed is prepared by hydrothermal denitration of thorium nitrate tetrahydrate (TNT) in a horizontal rotary denitrator (Fig. 1). The calciner shell in which the denitration takes place, with its clamshell heaters, is shown before assembly. The heaters and the calciner shell are shown in final assembly (Fig. 5). The TNT charge (30 kg) is loaded, and the 13.5 kg of Thoe product is discharged through this end of the calciner. The calciner is shown tilted to the unloading position. While operating, the shell turns on these trunnions. Deni- tration is accomplished in 5-1/2 hr at l;50°C under a super-heated steam atmosphere. The product obtained is a free-flowing powder, off-white in color, containing about 95% Tho2. The balance is water and nitric acid. As this unit was scaled up from a 2.5-kg scale without difficulty, further scale-up could undoubtedly be similarly accomplished. UNCt A$$10 it () [*40W J £, ( )?? ( , ue l 1810 * *** Qe {* * * * *W* * [** { "ctorasno" Most to a | Fl ... . ll. \t * Q \, ', }* * Q (l * i !- Rot.al \ ben it. I'm t . , " i in the Unl stad int, P.": it is in . * * ‘. . # '. t! w: 4. 'A' A's. . . . . * ...' ' | . . " s #############"A W***** l, * ": **** \ |\ \ , , ". ". ''' £a, "... , 't k . " " ' " ' ". . . . . . . . . . 2. b. UNC 1. A S S 15 || () [**40 W () 58/54 R! I'it'. 9. Donit 1' to the l l and Cl: un: he'll leater: . ... • A "* ...' ' . . . . .# , . . '...",".…" .' W * £ *: ** *:::::#: : lO In the Kilorod operation to date, this installation has processed lOOO kg of a total requirement of ll00 kg, without the rejection of a single batch or a significant equipment failure. A simple dispersion test with nitric acid and water, followed by visual examination of the resulting thoria Sol, is the only analytical acceptance test needed for the thoria batches. Thoria is a "natural" sol former, and one looks for only two things in this simple test: First the sol must wet the glass of a sample bottle uniformly, i. e., with no "chalky" streaks present. Second, the wetting sol film must have a blue color, recognized easily with experience. Denitrator operation is typical of sol-gel simplicity, reliability and ease of operation, "...i.2 Powder Blending - Great care is required to meet the uranium-thorium ratio specifica- tion (see Table 3 for definition). A batch blender was installed to provide large, uniform quantities of powder and thereby to assist in ratio control. The blender is a rotating-drum type and accepts a 70 to 80 kg charge. After blending, the powder is sampled and then weighed into 10-kg (+ 10 gm) batches. These batches are "bagged" into the sol-gel cubicle as one of the two feed materials for the blending operation. ls.l.3 Purification of U233 Feed Solution, An Operation for Removing Gamma-Emitting Daughters from #: in the #: Unlike the denitration operation, the extraction system in the strictest sense is not a portion of the sol-gel process; however, it is a Vital auxiliary. The U232 daughter products are gamma-ray emitters | 233 in order that the Kilorod equipment : and must be removed from the U may be operated with only gloved hands. The solvent extraction flowsheet used in this operation is shown on Fig. 6. The feed for the extraction plant is made up from aged uranyl nitrate solution or by dissolution of U233 metal. Following extraction, the purified uranyl nitrate solution U233 concentration of about 100 g/liter, is concentrated by evaporation to and it is then stored until needed in the sol-gel operation. The results of the extraction operation are given in Table l. Note that all specifications were met. The No:/U mol ratio is of significance in sol-gel operations, as will be discussed later. Decontamination SCRUB Al O.8 // HNOs O4 MAD UCLASSIFIED ORML-LR-Dw9,74963 R- STRIP WATER |DILUENT * DSBPP 2.5% DILUENT S7.5% U | us' Qf u"#" || |J|im.5%: Th O.03:/#ter | " | HNOs O.05A/ HNO3 OOO5A/ D.F. >|O4 Th 1339/liter TO STORAGE A | O.27 M --OR RECYCLE HNos 1.49 M TO SOL-GEL PROCESS Kilorod U233 Purification Flowsheet . * f l2 factors for hard-gamma-emitting isotopes are given in Table 2. These are the U232 daughter products previously discussed. Table l. Uranium Purification by Solvent Extraction Exceeds Purity Specifications Uranium DeContamination UNH Run Recovered Factor Product NO , % GroEST5 Thorium No3/U Ratio HJ -l 99.8 230 3 x 10° 2. l;2 HJ-2 99.6 380 5 x 10° 2.25 HJ-3 99.8 l;16 3 x 10° 2.16 Spec. 99.90 lOO 103 < 2.50 Table 2. Favorable Decontamination Factors in Solvent Extraction Gross y 250 Th228 2,500 Re32" . s 5,000 d Pb212 3OO QQ l;.2 Preparation of Sol-Gel Product Containing Thoa and U02 in Solid Solution The process described below provides a sol-derived gel that can be sintered to near theoretical density, and the process is simple and trouble free. *.2.1 Flowsheet Conditions Three individual operations make up the portion of the sol-gel . process within the shielded facility. These are: | l. blending of the sol, 2. evaporation (or drying) of the sol to a gel, and 3. calcination-reduction-sintering of the gel to the final product. | !si ********, *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*, * : , . . . . . . . . . . . l3 The flowsheet given as Fig. 7 lists operating conditions for each of these steps, as well as the operating conditions for the denitrator. l; .2.2 Procedure Preparatory to blending the batch of sol, the 10-kg batch of deni- trator product (Thoe) is bagged into the sol-gel cubicle. Precisely analyzed U233 feed solution is piped into the cubicle and a calculated Volume carefully measured. This volume is calculated to yield the desired U233/233 + Th ratio, The U233 feed solution is then transferred to the blend tank and a calculated quantity of nitric acid is added. The blending pump, which is installed on a pipe loop outside the blend tank, is started to agitate the batch. Steam is admitted to the steam heater, a jacketed section of the pipe loop. The amount of nitric acid added depends upon the total No: already present in the uranium solution and the quantity of thorium used. Sufficient nitrate is added to increase the No'-to-In ratio by O.077; if the No:/Th ratio is 2.5, then no nitric acid is added, and a ratio ~ 2.5 is not acceptable for processing (see Table 1). When the blend-tank temperature reaches 60°C, the thoria powder is added to the blend tank through a funnel at the top of the tank. During addition, the batch temperature continues to rise until it reaches 80°C, where it is controlled. The batch is allowed to agitate for 30 min at 80°C after the thoria addition. Ammonium hydroxide is then added in an amount equivalent to O. Ol'7 g-niole of NH,0H per g-atom weight of thorium. Circulation is continued for another 30 min; the batch is sampled; and it is then ready for transfer to the tray dryer. The inherent latitude of all sol-gel operations is well illustrated by the nitric acid and ammonia addition just mentioned. First, note that in nitrate addition no consideration was given to the quantity of nitrate in the Thoa feed. The Thoa is sufficiently uniform, and process control limits are so broad that the variation in nitrate concentration in the Thoe is not significant. The back adjustment with ammonia need not be controlled precisely, either. This adjustment is satisfactory over the NH,/Th mole ratio of O. Ol3 to 0.022. This broad control range actually allows some control of the crushing and grinding characteristics of the calciner product as toughness increases with the amount of ammonia added. *. ! STEAM THORIUM NITRATE DENITRATION SOLUTION 185-475°C (N 2 M) T STEAM 350-450°C DENSE UO2-Tho? TO SIZING AND UNCLASSIFIED ORNL-LR-DWG 7484 VIBRATORY COMPACTION # t: - 7. UO2(NO )2 H2O SOLUTION (~0.2M) SOL PREPARATION BLENDING, 80°C Tho? 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I Iw 1u E/I- 'i ul ogo, II on o.int.todulon uloo. uto.1.1 pos! at s! 3.Inn".toduo. toul otho otli, "...I ou I ol Bo otú on ul popuot ptin Sotoy cn.13 umptinTV on up podump si u on tid ou', ‘Rul A.Ip ...ton.JV pop.tod tu-o, a tead ‘o.66 on 09 at ano politbo 91 301 A.I.G Gl i 16 UNCLA$$1516 D P}4OWO 50412-RI *!. % * ' ' '," * * * } # Spicy Moisie. * # weshing Down wells of vessel ''', ' , , * * * ors." * . £". " # . . #. '''. ' w * : *i; ū (4000 meteoGew le w lett (aet showa) * , A: | “…. : *: Fig. 8. Cold-Testing Blend Tank. At this point in the preparation the uranyl nitrate solution is in the tank and be ready for thoria addition. Sol ing heated, UNCIA:3:3 IFIED PHOTO 98.315 Solids From Pump - Agitotow Sight Gloss A | Connection - i Fig. 9. Blend Tank. *Maussula. l * wr ww" *...*.*:M * * * * * * 'w, in '' ! is ;" • , , , "w, ' ' ' ' ' ' ' ... ** 'll) 1 * * ''1 1 ( ' ' ' ' ' ' ' ' ' ' ' ' ' ' W' " I''' * . " ". . . . . . '', - * @ ' ' , " | . " * , , , , , ” - - :- a ‘. . . .''." Rut. * * *.*.*.****** *w Fr", ww * ***"www". "war", " r - - - - - t !, a 1.4k. t/#4% '' w 1. - - r " ' ". . . . a k'ir ' ' ' , , , , - ** * - *. # # # # £: .# ! . . . . '...'", : * ... " ***.*... . . . . , s:... . . . . ####"…####". A 4 a.m. ... * * :'''' r: *: # #. ** ... ". . . .” u% '*'.",. '. * w: : w". *::: "... £: '*'. # # * Wi | ''''' *''''', UNCLASSIFIED PMOYO 50016. R. Type Troy Inclined Lower Lip of Troy Guide * , a W. s a it " *, * : ... "..."' m i . . " * * * ls "... ', ' , , '' I w! | "..." ". * * : '' ": '' '' r s * | | " *... ** . * , 'i 4. * #. * : * ' '. wi '* . . . " | *}. .." s i s * o Troy Filler " * . . . . . . . Positioning ... ." " . " '' '. * | '...' s " " " - "....." ". i , * * *:::: , - "it Y2 Fig. 10. Betch Evaporator with Trays Partially Pulled * | W' r . . . . . . " .. " . . . . . . . . . . . s . . ' ' ' 'I', ' ". ... '' . '' . . . . . . . ' ' ' ' ', " . . . . ' ' " . . . . . . . . . . " , "I " , * | wins' *** **i..., I.' '.' ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ' " . . . . | s . . . *: #4. 'a' *.*.*.*** "...i h: * * * * * * : "my, k … * } : ' ' ". . " "... ' ' ' ' ' ' ' ' " ' " , , , ' ' ' ' ' ' ' ' ' ' ". . . . ." . " * . . . . . . . ." e.' ' ' " . " " ' ". . . . . . . . . . . . . . . h i ". * * * * 1. *...I * * "w "N." * I'" . " * * , . " " ..." in Il- * - |-1's - • * "", " ' " , " ' " , liki' . . * : * * • - - ls - * * # *:::::::::: * * : , i. # ... '''',' '...' ...:"...', '', 'k', ' ' ', " ": "...'... . . . . . . . . . . . ... "1" |'', 'I, ...' ' ' ' ' ' , " ' " * , " ", , '' . ' ' ' ' ' '. l t II* , UNCLASSIFIED PHCYC 63257-RI Fig. ll. Evaporator Tray Containing Dried Gel, as Seen Through Cubicle-Shielding Window. . *... ". 1. . . . ... " ' . . . ..... . * '' . . . . ** # * : . . . ...'. ! . . . . . . . - - • - - ...''' i!'...". '* - "...' ... ." ". . '** . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " . . . . . . . **** *::##&#: ** *:::::::: * : *, ''. .. #. ". ... ', !. *.*, *, ' ' ', '…' * *, *, 1:1, Fig. 12. Batch Calciner, with Door Raised. latches permit operation by one gloved hand. UNCLASSIFIEO PHOTO 5823O-RI Door mounting and 2l revised to make manipulation easier. The heating element is Kanthal A-l. A sample of typical fired product is shown in Fig. 13. 5. RESULTS OF THE SOL-GEL OPERATIONS As of November 1, 1963, the sol-gel operation had produced 500 kg of U°oe-Thoe meeting chemical specifications. Within the period covered in processing the first 12 "hot" batches (about 120 kg), some difficulty was encountered in holding the weight percent U233 within the 3.00 + 0.09% specified. This difficulty lay entirely in our inability to agitate and sample the U233 feed tank properly. This difficulty was corrected by a new feed tank. Actually, all material prepared during this early period was usable since, it met all other specifications and since blending of the 233 various batches to obtain the desired percentage of U was permitted by the customer. Only one instance of equipment repair has been experienced in the sol-gel cubicle to date. This item was minor, delaying operations less than an hour. No cubicle entries, the indicator of major equipment repair, have been required. Kilorod specifications and analytical results obtained thus far are summarized on the following table: Table 3. Operating Results of the Sol-Gel Kilorod Prograla Specification Tsummary of Analytical Data or Desired Average Range Property Measured Max. Walue Walue Of Values 33 * U°33 x 100 3.00% + 0.05" 3. Ol 2.96-3.05 g 35 + Th Gas Release: w Calcined Product 0.05 cc/g max. O.O22 0.004-0.05 Crushed Oxide 0.3 cc/g max. O.ll O.05–0.28 "Powders falling within the 2.9-3.1 may be blended to yield the desired concentration. 233 Note that control of the percentage of U in the product has been ex- cellent and, in fact, is well within recognized limits of analytical error. The results of the first 12 runs, incidentally, are not included in this figure, because they are not representative of the control 22 UNCLASSIFIED PHOTO M2755-Ri Fig. 13. Sintered Sol-Gel Product. Shown here are typical shapes of cal ciner product . capability of the process as already discussed. Gas-release data for both the calcined product and the crushed oxide also show average and maximum values within the desired ranges. Actual 0/U ratios have not been determined for the "hot" product since proper facilities are not available. However, the actual oxygen present in stoichiometric excess is known to be low. Cold operations experience shows that a g is release for this product of ~ 0.03 cc/gm is < UO2.oh. This UO2.0, the lower analytical limit of detection for this uran um concentration. is actually Some pickup of gases is noted and expected in the preparation of the powder. No attempt is made to control this pickup because the powder is prepared in contact with the atmosphere. The composition of the gases released was also as expected. Hydro- gen, the gas of greatest interest, was not expected to exceed 50 vol % (see Table l;). The highest value thus far was 33%. The scatter and the uncertainties encountered in collection of the data make interpretation exceedingly difficult . Table 4. Quantity and Composition of Gases Released" by Solid Products CalcIned Productt. -Crushed OxTäge Gas Average Range Average Range Quantity of gases released: (std cc/gm) 0.022 0.004-0.06 0.ll 0.05-0.28 Analysis of gases released: (vol %) H2 7.6 0.7-16 2l l, -33 CH, l .5 O. 7-2 0.5 O.3-l H20 7.8 0.4-25 2. T 0.1-18 N2 or CO 30.9 O7-7l 39 7-59 92 l2. ' 0.3-56 0.6 O.l-3 A O. l; O.2-0. 7 O.l O.l-O.2 CO2 lil.8 Ol.9-73 l;0 6-83 “obtained by heating to 1200°C under vacuum. "Results represent first 28 calciner batches. "Results represent first l;0 rods. 2l; 6. KILOROD PROGRAM RADIATION DATA Compilation of radiation data from each of the sol-gel manipulations is an important objective of the Kilorod Program. These data are neces- sary for the design of future facilities and the handling of higher U232 concentrations. At the conclusion of the Kilorod program, the U232 COI) • tent of a batch will be increased to the equivalent of about 1000 ppm for radiation control data of interest to power reactor recycle work. Personnel exposures have been consistently well below permissible levels, and the accumulation of aet i Vlty by the equipment has also been low (Table 5). Individual hand and foretirm exposures will average about 100 millirems per week, as opposed to the 1500 permissible value. The highest rate recorded in surveying any equipment piece to date is 50 mr, found inside the calcin ing chamber. Radiation levels of process material: have been monitored, and the highest levels obtained are given in Table © . Dett iled data, in tiddlt ion, have been fitted to the calculated buildup curve, as shown in Fig. 14. Table 5. Personnel Radiation Exposures and Accumulated Activity in Equipment: Less than Maximum Permissible Max. Accumulated -FFT. Weekly Exposure Background" Operation (millirems) (millirems) Blending 7 6(a) Dryer "( 7(a) Calciner l') 50(b) Total Exposure to Individual < 200° "Exposure taken by a finger ring which is used only at the given work station. "This reading taken from individual finger ring which accumulates in- dividual dose for all duties. “Readings taken with G-M survey meter (a) and ion chamber (b). About 1/3 of program had been completed and all equipment given normal cleaning. F- * * * * * * * * *... * * * *** * * * * * *****, * * * **** –t Iw . * : * * 3. - * i i U233 SOLUTION - STORAGE . BEHAVIOR () | | | | | • r * } , s ... ." . . . . . . '' "... '" . . . . . * * * * *.*.*.*, *, *, *, *, *, *, '...' * * * * * > . . . . . . . . . . . . . . ' ' '. " . . . . . . . . . . . . . . . . . , ''': ' ' ' "…#,'?…"'''''''''''''' -t:'''''''''''''''''''44, #4,####". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * * * . . . .''''''''''''''' ". . .” #. ###, ########## ####### ######. ' ' ' ' ' ' ' ' ' ' ' ' … . . . . . . . . . . . . . . . . l l ! ", , , , " . • * M ; ; ". . . . M. : w . . . . . . . . ." . . . .'; ' '.' ' ' ' ' ' ', " , " … ' ' ' ' ' , , ''I'', ', TYPICAL KILOROD |OO 2OO 3OO 4OO 500 TIME SINCE PURIFICATION, hours UNCLASSIFIED | > | - CALCULATED () ****** * * * *** * * * , 600 1 h. TIA' A'tivity at a l'unction of Time Since Puritication. ORNL Dwg 63-422 R2 " " -->] s: " " 4 oth k" wril - “. wo. A * W. “ - 26 - Table 6, Radiation Levels of Process Materials WRXTREETIng-TEKen Days STREE Material (millirems/hr) Extraction Crucible of dried gel (5 kg)" < 20O 50 Crucible of fired particles (5 kg)" * 200 50 Finished rods" 77 78 96 98 ll3 l2l "G-M survey meter used. Probe held in contact with and across top of crucible. "G-M survey meter used. Probe held in contact with rod and with axis of rod and probe parallel. 7, FUTURE SOL-GEL WORK The variety of ceramic nuclear fuels which can be prepared by the sol-gel technique has already been mentioned. The materials already prepared on a laboratory scale by using variations of this procedure are given on Fig. 15. Note that uranium, plutonium, and thorium have been prepared in combination. Plutonium dioxide has also been prepared. Note that preparation of certain carbides has also been demonstrated. Further, since the preparation of this slide, the Thoa-Z102 combination has been made. The future of pilot plant work, lies within the products shown. An interesting variation, one yielding an unpowdered product, is used to illustrate the flexibility of the sol-gel process. Figure 16 shows microspheres of Thoe prepared by a sol-gel procedure. These microspheres are about 100 u in diameter. These same microspheres coated with pyrolitic carbon are shown on the following figure (Fig. 17). A microradiograph of these carbon- coated spheres is shown next on Fig. 18a and polished sections on 18b. The primary application for fuel in microsphere form lies in the prepara- tion of dispersion fuels. it'. : :-|i ||| :| | . ''#.b. * * | -| UNCLASSIFIED ORNL Dwg 64-2369 STARTING MATER ALS PRODUCTS FOrm J . C := -= Gel-Tho2-UC2 microspheres U02 (NO3)2–~ Sol = *- Gel —a-ThC2-UO2 Th(NO3)4—as-Tho2 == Sol —- Gel —- ThC2 PuO2(NO3)2 -e- Sol *- Gel —- Tho2-PuO2 Fig. 15. Examples of Flexibility of Sol-Gel Process. This flowsheet illustrates the many types of thoria based reactor fuels already prepared in the laboratory by Sol-Gel techniques. * "…": tra : " .… * *r---, - 16. 28 Sol-Gel Microspheres. UNCLASSIFIED 4 -RI PMOYO Y - T. * r ***** *** * * ****'. "'A'.…." k.v P.. "... • , * - t ********:::::::... . #| : ! ." X. * # # - y - £ :*: , #. i: '' 'Ali " * * | * l | * i * * # * * '''' : * 29 £2. | #6 Y52663-R C p l T l g (PMOYO W- $2660 O 1Q g X |:* * - I. # - U 75 x 2 (> IN CHES # incais o. Autor odiogroph b. Sections Fig. 18. Sol-Gel Thorium Oxide Microspheres. Notice in Fig. 18b that the coating (in cross section) the same as shown in Fig. 17 and Fig. 18a. 3l 8. CONCLUSIONS The Kilorod Program has reached the half-way point, and the follow- ing conclusions have been reached: l. The sol-gel process has been demonstrated at the 10 kg/day scale and has met chemical specifications. 2. Personnel exposures have in all cases been well below established limits. 3. Materials exhibiting considerably higher levels of radiation may be processed in the existing facility. The process represents a significant breakthrough in the preparation of ceramic reactor fuel materials. Kilorod operating results to date show that the sol-gel process offers advantages in simplicity, reliability, and ease of control. The flexibility of the sol-gel approach in preparing a variety of materials has now been demonstrated in laboratory tests. These other materials obviously can and will be made by this process. 9. ACKNOWLEDGEMENTS The efforts of the following Chemical Technology Division personnel are acknowledged in performance of the work upon which this paper is based and in the preparation of this paper: Messrs. J. L. Matherne, F. W. Miles, J. M. Chandler, L. J. King, D. E. Ferguson, The pyrolitic coating of the microspheres and the slides materials are the work of Mr. R. L. Beatty of the Metals Division. The analytical data and the patience of F. M. Sites are appreciated. The contributions of F. W. Davis and Wilcox Company are also acknowledged. and O. C. Dean. showing these and Ceramics Hill and J. R. Of the Babcock - *...* uult a *…*.* t . ... v. w ~ , i } \t £ " ' " ' "... 0- .3 £ # #. ;: }: '. '..." : , *'. '. A'. : * '' - #: ! f This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accu- racy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report. As used in the above, “person acting on behalf of the Commission” includes any em- ployee or contractor of ths Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Coromission, or his employment with such contractor. **** *** *-*"www". "