VASTER ORNL-2896 UC-4 - Chemistry=-General PHASE EQUILIBRIA IN MOLTEN SALT BREEDER REACTOR FUELS. . THE SYSTEM LiF-Ber-UF4-ThF4 C. F. Weaver R. E. Thoma H. Insley H. A. Friedman OAK RIDGE NATIONAL LABORATORY operated by UNION CARBIDE CORPORATION for the U.S. ATOMIC ENERGY COMMISSION DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Contract No. W-7405-eng-26 REACTOR CHEMISTRY DIVISION PHASE EQUILIBRIA IN MOLTEN SALT BREEDER REACTOR FUELS. I. THE SYSTEM LiF-BeF,-UF,-ThF, C.-F. Weaver R. E. Thoma H. Insley H. A. Friedman DATE ISSUED OAK RIDGE NATTIONAL LABORATORY - Oak Ridge, Tennessee operated by UNION CARBIDE CORPORATION for the U.S. ATOMIC ENERGY COMMISSION THIS PAGE WAS INTENTIONALLY LEFT BLANK 9! iii CONTENTS Abstract..eveecerencees ceecssesesnes ceessscssecs st esssenensnes s cesens 1. Introduction.eceveesoseesvrecacese teessecescsseasanae ecesecreesanas . 2. Experimental Methods..... cicsiessransas crccesnasannonas .o ceee 2.1 Techniques and ApparatuS..ccecereersescescssscencsanss criesas . 2.2 MaterialS...eoesse e eceanes Cecseaseccesesacsasecenosssssens 3. Phase Equilibria and Related Phenomena.....c.eeveeensenss crssnne 3 ol The Components LiF, BeF2 ) ThF4, and IJF4 LI R R B A N N I I I N B A S 3. 2 T:h.e SyStemS BEF2 -lI':hF4 and. BeF2 "UF4 oooooooooo . s e e TR EEEE 3.3 The System LiF-Ber oooooooo e s 00 o e s s 00 s s 008000 N EERE R N . 3.4 The SystemLi:F'TI]F/'oo.-..ooa.ooo-ooo oooooooo s e 068 L] * e T e . 3.5 The SyStemLiF-UF4-.......-.....-. oooooooooooooooo 6 080 P 3.6 The S'y'StEITl .UF4"ThF4lo ooooo A EEEEREEREEER) .o T EEEEE] ¢ NN s e 3.7 The System LiF-BeFo-UF4eeueeereoneraececcacnasannans cesaas 3.8 Tlle System LiF-BeF2 "'ThFZ'_ oooooooo s o s s e s es e e Y . * e o e 3 . 9 The System Ber'ThF4-UF4 " e 9 e s eSS s RS SE SIS OISR TR ESER "e * . . e 3 llo Tkle System LiF—‘[J‘FZ',"T’.b.‘Fer ® 2 8 ¢ 6 9o 3 20 00 s e e s e e e o 000 00 L) . 3.11 The System LiF-BeF,-UF,-ThF, (Selected Portions)......eeee. 4. AcknowledgmentsS...eeeveecosersscanse cesesesessseetsstsnrerernenn Appendix A Optical and Crystallographic PropertieS.ecesevccecces ceoe Appendix B Appendix C X-Ray Dittraction Data f'or the Solid Phases Observed in the Quaternary System LiF-BeF;-UF,;-ThF;..... Specific CompositionS.eecececceosseses Liquidus Temperatures and Primary Phases for 58 o PHASE EQUILIBRIA IN MOLTEN SALT BREEDER REACTOR FUELS. I. THE SYSTEM LiF-BeF,-UF,-ThF', C. F. Weaver R. E. Thoma H. Insley H. A. Friedman ABSTRACT The phase equilibrium relationships for the systems limiting the quaternary system LiF-BeF,-UF,-ThF, are described in detail along with available information on the quaternary system itself. The implications of the extensive solid solutions in the limiting systems are discussed and experimental information supporting the conclusions is presented. U The optical properties, crystallographic properties, and x-ray diffrac- tion patterns for the phases occurring in these systems are tabulated. Specific compositions of project interest to which references have been made in the ORNL literature are given special attention. Reference is made to literature reporting properties of these materials.other than those discussed in this report. ~ 1. INTRODUCTION Fluoride fused salts have attracted general interest for use in high- tempefature reactors because: (1) fluorine has a very low thermal neutron absorption cross section,® (2) fluorides have low vapor pressures at tem- peratures and compositions of i.n.terest,2 (3) molten fluorides are very 2 and (4) there are no serious resistant to damage by nuclear emissions, corrosion probleme between many fluorides and nickel-based structural ma- terial.? Specifically, uranium tetrafluoride, a fissile material, is of interest because it is the only nongaseous fluoride of uranium which does not incur serious metal container corrosion and/or fuel inhomogeneity as 3 an effect of high-temperature disproportionation. Thorium tetrafluoride, 1s. Glasstone, Principles of Nuclear Reactor Engineering, p 841, Van Nostrand, Princeton, N.J., 1955. °H. G. MacPherson, p 567 in Fluid Fuel Reactors, ed. by J. A. Lane, H. G. MacPherson, and F. Maslan, Addison-Wesley, Reading, Mass., 1958. 3W. R. Grimes et al., p 577 in Fluid Fuel Reactors, ed. by J. A Lane, H. G. MacPherson, and F. Maslan, Addison-Wesley, Readlng, Mass., 1958. a fertile material, is the only fluoride of thorium._4 The fluorides PbF,, BiF3, Li’F, NaF, ZrF,, and BeF, have sufficiently low thermal neutron ab- sorption cross sections, vapor pressures, and melting points to allow their use as diluents for the UF, and ThF,. However, PbF, and BiF3; are unsuit- able because the cations are readily reduced to the metallic'state by 5 The lower thermal neutron structural metals such as iron and chromium. absorption cross section of Ii”7 as compared with that of sodium allows the design of reactors which have a smaller holdup of fissile material and superior breeding performance.6 Fluid salt mixtures containing high concentrations of ZrF, are not regarded as attractive reactor fluids because of significant vapor pres- sure of ZrF, above 500°C. In a reactor system sublimation of Zng fol- lowed by deposition as a solid limits the temperatures at which long op- erating times are permissible. Comparable limitations do not occur in mixtures containing BeFé rather than ZrF4.7 Molten salt reactor systems which are designed to operate at sufficiently high temperatures that al- kali fluoride—ZrF, solvents containing 30-40 mole % ZrF, can be employed may offer advantages in the futuré, but present preference must be given to BeF, on the basis of sublimation.® Consequently, mixtures containing Li’F, BeF,, UF,, and ThF, which have liquidus values severallhundred de- greesibelow the ThF, and UF,; melting points are the mdst promising éore materials for a fused salt thermél breeder/converter reactor. A knowl- edge of the liquidus values of such mixtures is necessary since as reac- tor fluids fihey must remain wholly in the liquid state during reactor op- eration. Liquidus data alone are insufficient because mixtures of solids and liquids will be formed during some fuel handling operations. A knowl- edge‘of‘the nature of the'melting-freezing process, of the ufanium-thbrium partition or phase'separation during this process, and of the identity of 4Tbid.,-p 588. °Tbid., p 570. ' ®MSR Quar. Prog. Rep. Jan. 31, 1958 ORNL-2474, p 1. " "H. G. MacPherson, ORNL, personal communlcatlon. 8. R. Grimes et al., p 582-84 in Fluid Fuel Reactors, ed. by J. A. Lane, H. G. MacPherson, and F. Maslan, Addison- Wesley, Reading, Mass., 1958. i b solids formed on cooling of molten mixtures is also necessary. Thus, the phase equilibrium relationships for the quaternary system must be under- stood, especially near liquidus temperatures and at compositions which may afford attractive core or blanket materials. Before the determina- tions of the phase relationships can be made in a quaternary system, the 14 limiting unary, binary, and ternary systems must be understood. All these limiting systems for the quaternary system LiF-BeF,-UF,-ThF, have been reported and are described in detail in the body of this report along with the available data on the quaternary system itself. It is remarkable that these studies have not disclosed the existence of ternary or -of quaternary compounds. The majority of the informdtion included in this report was derived in the High Temperature Phase Equilibrium Group of the Reactor Chemistry Division at the Oak Ridge National Laboratory. Some of the preliminary studies of the phase equilibria in the limiting binary and ternary sys- tems were begun as early as 1951. 2. EXPERIMENTAL METHODS 2.1 Techniques and Apparatus The experimental techniques and apparatus used in the studies of LiF-BeF,-UF,-ThF, phase equiiibria have been described in detaill else- where.®"13 1In general, the data were obtained by thermal analysis of slowly cooled melts and by quenching mixtures which had been equilibrated at known temperatures. Commonly, fused-salt diagrams are based entirely on information from cooling curves (temperature of the sample plotted as a function of time). Changes in the slope of the cooling curve reflect phase changes which occur on cooling, but.are prone to give misleading or irrelevant indications because of the impossibility of maintaining equilibrium during the cooling process. Consequently, predominant use °%C. J. Barton et al., J. Am. Ceram. Soc. 41, 6369 (1958). 10c, J. Barton et al., J. Phys. Chem. 62, 665 (1958). 11y, A. Friedman, J. Am. Ceram. Soc. 42, 284-85 (1959), 12p, A. Tucker and E. F. Joy, Am. Ceram. Soc. Bull. 36, 52-54 (1957). 13L. J. Wittenberg, J. Am. Ceram. Soc. 42, 209-11 (1959). has been made of the much more effective method of quenching.equilibrium . samples and identifying the phases by examination with a polarizing light mlcroscope and by x-ray dlffractlon techniques. A thermal gradient furnace with a single movihg thermocouplel? is used for equilibration in the temperature range 650-1200°C. . Five other thermal gradient furnaces, operating at a maximum temperature of 900°C, incorpérate 18 thermocoufiles.each. The independent readings from these aré'used.to”determine a temperature calibration curve of the thermal .gra- dient within the annealing area of the furnace. Malfunction of a single thermoéouPle-becomeé readily apparent.. In quenching studies made at tem- peraturésvbelow 900°C, sample tubes are distributed among the five fur- - naces randomly, to achieve méximum reproducibility among independent tem- perature readings. The region of temperature overlap, 650-900°C, is used to monitor the single highfitemperéture furnace. 1In the absence of super- cooling effects, the completely separate measurements in.the thermal.anal- .- ysis furnaces agree within 5°C with those from the thermal :gradient. fur- naces. This interlocking system, by which multiple'fhermocouples'within five .of the furnaces and three typeé of furnaces are used, provides a continuous-chéck on. the proper function of the equipment. , The accuracy of the temperature‘measurements'ileimited by the char= acteristicé.of the. Chromel-Alumel thermocouples used.l4 The invariant point temperature data are so precise that a standafd deviation of:l or -~ 2° is obtained. 2:2 Materials The LiF used for this work was reagent grade obtained from Foote Mihepal Company and from Maywood Chemical Works. The UF4 was a product of Mallinékrodt Chemical Works. The ThF, was obtained from Towa State College and from National Lead Company. The BeF, was a product of Brush é% Beryllium Company . No 1mpur1t1es were found in any ‘of these materials. by x-ray diffraction or microscopic analy51s. Spectroscopic analy51s in- - dicates less than 0.25 wt % impurities. 147, F. Potts, Thermocouple Research — Cold Work, ORNL CF-59-6-61 (June 15, 1959). Because thorium!® and uranium fluorides are easily converted to ox- ides or oxyfluorides at elevated temperatures it was necessary to remove small amounts of water and oxygen as completely as possible from the starting materials. In a few cases the molten mixtures were treated with anhydrous HF. For the vast majority of preparations, however, NH,F-HF was added to the mixture before melting. As such mixtures are heated the watcer evaporates from the system. 'I'race quantities of oxide impuri- ties are converted to products which have not yet been identified but nl6,17 ypon further heat- which are likely to be ammonium "fluometallates. ing the ammonium "fluometallates" and the excess NH,F-HF decompose. The products are metal fluorides and the gases NH3 and HF. These gases are quantitatively swept from the system by dry helium. The samples were melted and cooled to obtain thermal analysis data. The purified solids were transferred to an argon-filled dry box which contained BaO as a des- iccant. They wcre grofind to pass a 100-mesh screen and used in the S quenching experiments. The heating cycles were conducted in closed cap- TG sules or under an atmosphere of dry helium or argon. 3. PHASE EQUILIBRIA AND RELATED PHENOMENA 3.1 The Components LiF, BeF,, ThF,, and UF, - o A special character can be assigned to the behavior of combinations of the four compounds LiF, BeF,;, ThF,, and UF,, for in this grouping are to be found a pair of metal cations in the lowest and a pair in the high- est atomic number range. It might, therefore, be expected that the di- verse physical and chemical properties of these four components would contribute to the occurrence of phase behavior in which a wide variety of phenomena would appear. The melting points of the components are shown in Table 1. Of the four components, only BeF, exhibits polymorphic transitions. The equilibrium melting temperature and the nature of these solid-state 1°R. W. M. D'Bye, J. Chem. Soc. 1958, 196. l'E’MSR Quar. Prog. Rep. Apr. 30, 1959, ORNL-2723, p 93. 178, J. Sturm, ORNL, personal communication (May 1960). ‘Table 1. "The Melting Points of the Components Melting Point Component ‘ (°c) LiF g45% BeF», 548b—d ThF,, 1111578 UF,, 1035" %7, B. Douglas and J. L. Dever, J. -Am. Chem. Soc. 76, 4824 (1954). b LiF- BeF2 ThF4," J. Phys. Chem , in press. D. M Roy, R. Roy, and E. F. Osborn, J. Am. Ceram. Soc. 36, 185 R. E. Thoma et al., "Phase Equilibria in the Systems BeF,-ThF, and (1953). ' @M. P. Boryenkova et al., Zhur. Neorg. Khim. 1, 2071 (1956). R. E. Thoma et al., J. Phys. Chem. 63, 1266 (1959). J. Asker, E. R. Segnit, and A. W. Wylie, J. Chem. Soc. 1952, 4470. ®A. J. Darnell and F. J. Keneshea, Jr., J. Phys. Chem. 62, 1143 (1958). ‘ ’ hH. R. Hoekstra and J. J. Katz, p 177 in The Actinide Elements, ed. by G. T. Seaborg and J. J. Katz, McGraw-Hill, New York, 1954. transitions have been the subject of controversy for several- years. 18 The structure of Bng is analogous to that of S5i0Oz, as.was predicted by . | Goldschmldt 19 211 known modifications crystalllze as S1i0,-type struc- tures. Belng similar to 8102, Bng readily forms a glass upon cooling _ from the liquid state. For this reason, establishing solid-state equl— libria with BeF,, in which devitrification of this glass must be accom- plished, is often a very slow process. Opticél and crystallographic properties for the compounds fiiF, Bel'y, ThF,, and UF, may be found in Appendix A. Their x-ray diffraction data are listed in Appendix B. ' . ' ' 187, V. Novoselova, Uspekhi Khim. 27, 33 (1959). - 1%, M. Goldschmidt, Skrifter Norske Videnskaps-Akad. Oslo. I. ‘Mat.-Naturv. Kl. 1926, No. 8, p 7-156 (1927). » 3.2 The Systems BeF,-ThF, and BeF,-UF, The systems BeF,-ThF;?° (Fig. 1) and BeF,-UF,?! (Fig. 2) are similar ‘UNCLASSIFIED ORNL-LR-DWG 245514 in that both possess no interme- 1300 —————————— x diate equilibrium compounds, have e THERMAL ANALYSIS RESULT 1200 |- * NoF-BeF,~Thi, EXTRAPOLATION RESULT lowest liquidus values between s THERMAL GRADIENT QUENCHING RESULT 100 | < 97 and 100 mole % BeF,, have a - LIQUID 'y .. . . € 1000 T single eutectic invariant point, w /( o 2 500 7 and have an abrupt change in the B /./ . b - Q. y—® Z 800 I 20 1 - }// LIQUID +ThF, R. E. Thoma et al., "Phase 700 / Equilibria in the Systems BeFj,- co0 g/ HOUD + BeFy ThF, and LiF-BeF,-ThF,," J. Phys. Ve {Ber, +ThF, Chem. ; in press. L a l g . 500 7 l 1T. B. Rhinehammer, P. A. o 0 %0 %0 Mo S0 B0 To 80 s 1 Tucker, and E. F. Joy, Phase Equi- 2 ¢ . libria in the System BeF,-UF,, Fig. 1. The System BeF,-ThF,. MILM-1082 (to be published). UNCLASSIFIED . ORNL-LR-DWG. 28598 oo ] T T T T T I T | T ] T I | | T [ T 1000} - o _ LIQuip 900} - - ¥a00l- - w : UF4 + LIQUID > [ < w 0. 700 - = 7Y - 600} i T %0—00—0000-0-0-0-0-0-00——0—05—v oo — ] QMigH BeFa +UF, 400 | l 1 l i l | l 1 l | 1 l 1 l | l 1 0 10 20 30 a0 50 60 70 80 90 100 BoFp MOLE PERCENT UF4 UFs FPig. 2. The System BeF,-UF,. liquidus slope in the quadrivalent fluoride primary phase region. The eutectic invariant points are at 2 mole % ThF,, 527°, and at 0.5 mole % UF4, 535°, while the change in slope occurs near 12 mole % ThF, and 7 mole % UF; in the corresponding systems. 3. 3 The System LiF- Bng A phase dlagram of the system LiF-BeF,22:23 (Fig. 3) has been derived at ORNL from the results of thermal gradient experiments. A phase diagram nearly identical with that shown has been derived independently at the 22R, E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials, ORNL-2548, p 33 (Nov. 2, 19597. 23R, E. Moore, C.. J. Barton, R. E. Thoma, and T. N.. McVay, ORNL, un- publlshed data. ‘ UNCLASSIFIED ORNL—LR—-DWG {6426R 900" 800 \‘\ ' 700 —N\ %) £ 600 [——LiF + LIQUID - *:; \ [ . - - 2 - \ . — w C . a . S 500 . / BeFp + LIQUID 400 ‘ 2L|F BeFa\ - LIQUID \\/ Lif + 2LiF - BeFp by 2LiF - BeFp + BeF, (HIGH QUARTZ TYPE) 300 l@ | j = 2LiF-BeF, W ! Lo o ~ T 2 9 LiF - BeFo+ BeFp (HIGH QUARTZ TYPE) ' UF-Ber, & 1 | 1 ' 200 IF-BeFp 3 LiF - BeFo+ BeF2 (LOW QUARTZ TYPE) _ LiF 10 20 30 - 40 50 - 60 70 80 90 Bef, BeFla (mole %) Fig. 3. The.System -LiF-BeF,. Mound La'boratory.24 These diagrams are revisions of those published by earlier investigators:?° 27 Two equilibrium compounds occur .in the system LiF-BeF,, the incongruently melting compound 2LiF.BeF, and the subsolidus compound LiF.BeF,. Unsuccessful attempts have been made by the authors to produce the reported compounds 3LiF.2BeF,28 and LiF-2BeF,2° by devitri- ' fication of LiF-BeF, glass and by solid-state equilibration of mixtures of BeF, and 2LiF-.BeF,. Because the special purification techniques de- scribed earlier in this report were not used by other investigators??:28 reports of the existence of 3LiF.2BeF, and LiF.ZBng should be considered tentative. The optical properties, crystallographic properties, and x-ray dif- fraction data for the compounds 2LiF.BeF,; and LiF.BeF, are listed in Ap- pendixes A and B. The compositibns and temperatures of the two invariant points and one upper limit of stability may be found in Table 2. Table 2. Invariant Equilibria in the System LiF-BeF,* Mole % Invariant Type BeF, in Temperature of Fhase Reaction at 2 . Liquid (°c) Equilibrium Invariant Temperature 33.5 454 Peritectic "L + LiF = 2LiF.BeF, 52 355 Eutectic L = 2LiF.-BeF, + BeF, - 280 Upper temperature 2LiF.BeF, + BeF, = LiF-:BeF, of stability for LiF.BeF, *¥R. E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials, ORNL-2548, p 33 (Nov. 6, 1959). Cooling mixtures of LiF and BeF, slowly from the liquid to the solid state rarely produces equilibrium solids, for the subsolidus reaction 243. F. Eichelberger, C. R. Hudgens, L. V. Jones, and T. B. Rhine- hammer Mound Laboratory, unpuihlished data. °D. M. Roy et al., J. Am. Ceram. Soc. 37, 300 (1.954). 2°A V. Novoselova et al., J. Phys. Chem. (USSR) 26, 1244 (1952). 27J. L. Speirs, Ph.D. thesis, University of Michigan, May 29, 1952. 28F, Thilo and H. A. Lehmann, Z. anorg. Chem. 258, 332-55 (1949) Ceram. Abstr. 1950, 82f. - ‘conditions. 10 Li,BeF, + BeF, — 2LiBeF3 proceeds very slowly. The compound LiF.BeF, ~ may be observed to grow slowly into solid'mixtures of LiF and BeF, which are held for several days at temperatures just below 280°C. ‘The fofma— tion of LiF-BeF, glass which devitrifies slowly also prevents compositions rich in BeF, from reaching equilibrium.rapidly. Mixtures of LiF and BeF'5, - containing more than 33.3 mole % BeF, regularly contain only Z2LiF-BelF, and the low-quartz form of BeF, if fhey are cooled under nonequilibrium 29, 30 The compositions, liquidus temperatures, and primary phases for mix- tures of LiF and BeF, which have been referred to in the ORNL literature as C-74, C-112, and C-132 may be found in Appendix C. Solubilities of NaF,3' RbF,32 zrF,,33 PuFs,3% CeFs,35 HF,3% and the 37 noble gases in LiF-BeF, solvents have been reported. The reactions M + HF (M = Fe, Cr, or Ni),3® CeF; + Be0,3? and CeF; + Hp0%® in LiF-BeF, sol- .. vents have been investigated, as have the exchange reactions between CelFj ~and CeO, and between HfC and HfF,.%1 2°R. E. Thoma, X-Ray lefraction Results, ORNL CF-56-6-25, item T- 1437 (JUne 4, 1956) 30R. E. Thoma, Results of X- Ray lefractlon Phase Analyses of Fused Salt Mixtures, ORNL CF-58-2-59, item 1894 (Feb. 18, 1958). _ 31R. E. Thoma (ed ), Phase Diagrams of Nuclear Reactor Materials, ORNL- 2548, p 42 (Nov. 2, 1959). °Tbid., p 44. 33MSR Quar. Prog. Rep Jan. 31 and Apr. 30, 1960, ORNL-2973, p 65. 34C. J. Barton et al., Reactor Chem. Ann. Prog Rep Jan. 31 1960, ORNL- 293l, p 12. 30w, 1. Ward, R. A. Strehlow, and G. M. Watson, Chem. Ann. Prog. Rep. June 20, 1958, ORNL-2584, p 82. 36J. H. Shaffer and G. M. Wetson, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 31. . 37N, V. Smith et al., Reactor Chem. Ann. Prog. Rep. Jen. 31, 1960, ORNL-2931, p 28. ~ | 38¢c. M. Blood et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL—2931, p 39. T - 397, H. Shaffer, G. M. Watson, and W. R. Grlmes, Reactor Chem. Ann. Prog. Rep.. Jan. 31,. 1960, ORNL-2931, p 86. 401pig. , p 88. 4TF H. Shaffer and G. M. Watson, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL- 2931, p 82-84. 11 3.4 The System LiF-ThF, One congruently melting compound (3LiF.ThF,) and three incongruently melting compounds (7LiF-6ThF,, LiF-2ThF,, and LiF.4ThF,) are formed in the system LiF-Tth,42 (Fig. 4). Optical properties, crystallographic properties, and x-ray diffraction UNCLASSIFIED ORNL-LR-DWG 265354 150 — data for these compounds are listed (050 . //”// in Appendixes A and B. The com- 950 ////// positions and temperatures of the five invariant points and one con- /// gruent melting point may be found 750 AN / \\ // in Table 3. 650 \ \»q/ Binary LiF-ThF, mixtures con- 3LiF - Thiy—{ 7LiF-6ThF—~= LiF- 2Thi— TEMPERATURE (°C) - LiF-4ThE, taining more than 25 and less than | | l 450 LUF 40 20 30 40 50 60 70 80 90 Thg, 66.7 mole % ThF, regularly contain Thf, (mole %) ‘ 3LiF.ThF, and LiF.-2ThF, if cooled Fig. 4. The System LiF-ThF,. from the liquid state under non- 43 equilibrium conditions. The solidification temperature is not signifi- cantly changed by the failure of 7LiF¥F.6ThF, to form.%? The equilibrium “2R. E. Thoma et al., J. Phys. Chem. 63, 1266 (1959). 43R. E. Thoma, Results of X-Ray Diffraction Phase Analyses of Fused Salt Mixtures, ORNL CF-58-2-59, items 1854, 1873, and 1894 (Feb. 18, 1958). Table 3. Invariant Equilibria in the System LiF-ThI',* Mole % Invariant Type Phase Reaction ThF, in Temperature ~ of at Invariant Liquid (°c) Equilibrium Temperature 23 565 Eutectic = LiF + ' 3LiF-ThF, 25 . 573 Congruent mp L = 3LiF.ThF, 29 568 Eutectic L = 3LiF.ThF,; + 7LiF-6ThF,, 30.5 597 Peritectic LiF.2ThF, + L == 7LiF-6ThF, 42 762 Peritectic LiF«4ThF, + L = LiF-2ThF,, 58 897 Peritectic ThF, + L = LiF-4ThF, XR. E. Thoma et al., J. Phys. Chem. 63, 1267 (1959). .t Rark 2k~ FPIRNILITN 12 B - @ condition will be readily establlshed if the LiF-ThF, mixtures are held D ’ for a short time at temperatures Jjust below the solidus. KA " The comp081t10n, liquidus temperature, and prlmary phases for the mixture of LiF and ThF, referred to in the ORNL literature as C-128 may be found in Appendlx C. | 3.5 The SyStem LiF-UF, Three incongruently melting compounds (4LiF.UF,, 7LiF.6UF,, and LiF.-4UF,) are formed in the system LiF-UF,° (Fig. 5). The metastable UNCLASSIFIED ] ’ ORNL —LR-DWG 17457 - {100 700 \\\ : : / - TEMPERATURE (°C) 600 : N\ | 500 - - / s < LA = 3 E aLiF-ug,—" = W - ~ -} 400 - — : . . LiF " 10 20 30 40 50 60 70 80 90 UF, UF4( mole To) Fig. 5. The System LiF-UF,. _ N compound 3LiF-UF,; is readily formed from melts containing approximately 25 mole % UF, at temperafures above the indongrfient melting point‘bf | 4LiF-UF, when these_mixtures are rapidly cooled from fhe liquid state. The cooling curves of samples,in”thie composition range differ remarkably from one another depending upon thé maximum temperature of the-mirture . e just prior to cooling. 13 The optical properties (except for 3LiF.UF,), crystallographic prop- erties, and x-ray diffraction data for these compounds may be found.in Appendixes A and B. The compositions and temperatures of the four in- variant points and the lower temperature limit of stability for 4LiF-.-UF, may be found in Table 4. The systems LiF-ThF, and LiF-UF, are similar Table 4. Invariant Equilibria in the System LiF-UF,* Mole % Invariant Type of UF, in Temperature oG Phases Present . o Equilibrium Liquid (°c) - 470 Lower stability LiF, 4LiF-UF,, limit for 7LiF«6UF, . 41IAF.UF, 26 500 Peritectic LiF, 4LiF.UF,, liquid liquid 40 $10 Peritectic 7LiF+-6UF,, LiF-4UF,, liquiad 57 775 Peritectic LiF+4UF,, UF,;, liquid *C. J. Barton et al., J. Am. Ceram. Soc. 4L, 63-69 (1958). in that in each the lowest liquidus temperatures are found between 70 and 80 mole % LiF, and in Both systems compounds with alkali fluoride ratios of 3:1, 7:6, and 1l:4 are formed. The compounds 7LiF.6ThF, and 7LiF.6UF, form a continuous series of solid solutions as do the compounds LiF.4ThF, and LiF-4UF,. These solid solutions are described in Sec 3.10 and Ap- rendix A. The solubilities of NaF,%* KF,%> RbF,%® and UF3%7 in LiF-UF, solvents have been investigated. The vapor pressures of LiF-UF, mixtures containing 10 and 20 mole % LiF have been reported.*8 44R. E. Thoma et al., J. Am. Ceram. Soc. 42, 21-26 (1959). 45R. E. Thomalrgdtj, Phase Diagrams of Nuclear Reactor Materials, ORNL-2548, p 98 (Nov. 6, 1959). 461pid., p 102. 47C. J. Barton et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 26. T 48g, Langer, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 51. 14 IS 3.6 The Systeni UF,-ThF, - S S K The isostructural components ThF4 and UF4 form a contlnuous serles - . 1)§ UNCLASSIFIED of solid solutions w1thout max1- ORNL-LR-DWG 27913R 1200 mum or minimum*® (Flg 6). The . £ 1100 teses—— — LIQuio 1nd1ces of refraction of the l&" -‘\‘ m:‘:m__ 1 . b EEE == . . 2 1000 LIQUID + ThF, - UF, SOLID SOLUTION ThF,-UF, solid solutions change a Lu ’ ’ » X . 3 ' = 900 The, - UF, SOLID SOLUTION . regularly with composition but = . . . . 800 | l | not linearly. The optical prop- ThE, 10 20 30 40 50 60 70 80 90 UF, . o : . ) UF, (mole %) * erties for these solid solutions Fig. 6. The System UF,-ThF,. may be found in Appendix A. 3.7 The System LiF-BeF,-UF, Nolternary compounds form within the system LiF-BEFg-UF450’5l (Figs. 7 and 8). Consequently, the solid phases occurring in the system are those of the components or binary compounds described above (Secs 3;1, 3.2, 3.3, and 3.5). The compositions and temperatures of the five in- .variant poinfis may be found in Table 5. Thé equilibrium phase behavior of selected compositions of LiF-BeF,-UF, is given in Table 6 and.in Ap- ‘pendix - Co When mixtures of LiF, Bng, and UF, cool slowly from the lig- uid state, equlllbrlum is rarely, if ever, achieved. 1In the comp081tlons c-75, C-126, C- 130, C-131, and C-136 solids have been routlnely observed in the cooled.melts Wthh are indicatlive of nonequlllbrlum cooling. 352=54 490, F. Weaver et al.,rPhase Equilibria in the Systems UF,-ThF, and L1F UF4-ThF4, ORNL-2719- (Aug. 17, 1959), J. Am. Ceram. Soc. 43 213 (1960). °0L. V. Jones et al.,- Phase Equilibria in the LiF-BeF,- UFfi»Ternary Fused Salt System, MLM—lO8O (Aug. 24, 1959).. 51R. E. Thoma (ed. ), Phase Dlagrams of Nuclear Reactor Materials, ORNL-2548, p 108-9 (Nov. 6, 1959). °2R. E. Thoma, Results of Examinations of Fused Salt Mixtures by -3 Optical and X-Ray lefractlon MEthods, ORNL CF-58-11-40, item 1925 (Nov. 14, 1958). 23R. E. Thoma, Results of ‘X-Ray Diffraction Phase Analyses of Fused - Salt Mixtures, ORNL CF-58-2-59, items 1873 and 1894 (Feb. 18, 1958)." °%R. E. Thoma, Results of Examinations of Fused Salt Mixtures by Optical and X- -Ray Diffraction Methods, ORNL CF-59-10-18, 1tems 2006 2019, 2036 2056, 2061 and 2074 (Oct. 7, 1959) : . 15 Solid-state equilibrium is readily established if the solid mixture is annealed for a short time at temperatures near the solidus. UNCLASSIFIED MOUND LAB. NO. 1035 56-141-29 (REV) UF, ALL TEMPERATURES ARE IN °C £ = EUTECTIC P = PERITECTIC LiF'4UF4 UF, | = PRIMARY PHASE FIELD Fig. 7. The System LiF-BeF,-UF,. Numerous investigations of the interactions of molten mixtures of LiF, BeF,, and UF, with other substances have been reported. The solu- 2LiF - BeFp+BeF, LiF- Ber + BCFZ LiF +2LiF - BeF, 2LiF - BeF, 2LiF-BeF, +LiF - BeF, Fig. 8. The System LiF-BeF,-UF,. BBFZ Table 5. Invariant Equilibria in the System LiF-BeF,-UF,* Composition of il Tempera- Solid Phases e (mole %) ture TYP? O? Present at (*g) IRt Invariant Temperature LiF BeF, UF, 72 6 22 480 Peritectic (de- 4LiF-UF,, LiF, and composition of 7LiF.6UF, 4LiF-UF,; in the ternary system) 69 23 8 426 Eutectic LiF, 2LiF+BeF;, and 7LiF«6UF, 48 51.5 0.5 350 Eutectic 7LiF<6UF,;, 2LiF-BeF,, and BelF', 45.5 54 0.5 381 Peritectic LiF-4UF,, 7LiF-6UFy, and BeF's, 29.5 70 045 483 Peritectic UF,, LiF-4UF,;, and BeF', *¥R. E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials, ORNL-2548, p 109 (Nov. 6, 1959). 17 Table 6. Phase Behavior of Selected LiF-BeF,-UF, Compositions Tem%fé?ture Phases Present Cc-75: 67 LiF-2.5 UF,~30.5 BeF, (Mole %) 464—450 LiF and liquid 450426 LiF, 2LiF-BeF,, and liquid Below 426 LiF, 2LiF-BeF,, and 7LiF.6UF, C-126: 53 LiF-1 UF,—46 BeF, (Mole %) 400-350 2LiF+BeF,, 7LiF.6UF;, and liquid 350-280 2LiF-BeF2, 7LiF’6UF4, and BeF; Below 280 2LiF+BeF,, 7LiF+6UF,, and LiF-BeF, C-130: 62 LiF-1 UF,-37 BeF, (Mole %) 40—414 2LiF+BeF, and liquid 414~381 2LiF+BeF,, 7LiF+6UF,, and liquid 381280 2LiF+BeF,, 7LiF-6UF,, and BeF, Below 280 2LiF-BeF,, 7LiF-6UF,, and LiF+BeF, Cc-131: 60 LiF—4 UF,—36 BeF, (Mole %) 450~415 7LiF+6UF, and liquid 415381 7LiF+6UF,, 2LiF-BeF,, and liquid 381-280 7LiF-6UF,, 2LiF-BeF,, and BeF, Below 280 7LiF.6UF,, 2LiF-BeF,, and LiF-BeF, C-136: 70 LiF-20 UF,—10 BeF, (Mole %) 500-465 7LiF+6UF, and liquid 465426 7LiF+6UF,, LiF, and liquid Below 426 7LiF.6UF,, LiF, and 2LiF-BeF; 18 bilities of PuFs3,1? CeF3,°° LaF;,°° and SmF3°° in LiF-BeF,-UF, solvents and the reactions of Be0’® and steam’” on these solvents have been in- vestigated. The exchange of SmF; (dissolved) and CeF; (solid),”8 the exchange of Hf in HfF, and HfC,”° and the effect of AlF358 on the solu- bility of the rare-earth trifluorides in LiF-UF,-BeF, molten mixtures have been studied. In addition the effect of thermal cycling on segre- gation,6o the effect of radiation on static corrosion of graphite and 3 64 of INOR-8,6l graphite per.meation,62 dehydration,6 and purification have been reported for LiF-UF,-BeF, mixtures. 3.8 The System LiF-BeF,-ThF, The phase equilibria in the system LiF-BeF,-ThF, (Figs. 9%-15) have been described in a recent report.20 One aspect of the phase equilibria in this system which is of significance is the formation of a solid so- lution in which beryllium replaces both lithium and thorium in the 3LiF-ThF, lattice. The single-phase composition area for this solid so- lution is limited as indicated in Table 7. This results in the forma- tion of phases at the solidus whose compositions are not so diverse as those which would have been formed if the substitutional solid solution °R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 77. T 57, H. Shaffer, G. M. Watson, and W. R. Grimes, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 84. 57Tpid., p 87. >8R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 77-80. ~— °9J. H. Shaffer and G. M. Watson, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 83. 60G. J. Nessle and J. Truitt, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 17-19. 6ly. E. Browning and H. L. Hemphill, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 74-75. ®2R. J. Sheil et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 69. 63c. J. Barton et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 20. o 64J. E. Eorgan et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 64. T 19 - UNCLASSIFIED ORNL-LR-DWG 37420R2 Thi, 1414 TEMPERATURE IN °C COMPOSITION IN mole 7o LiF-4ThE, | , LiF-2Th, " P 762 A 850 e & D wo N ————— " \\;£ 576 (o) N> — = = g LiF O\/ \ \\ \\\f A VA ) 5 \V X AVA > Ber 845 2LiF-BeF, 5001450 400 400 450 500 548 P 465 £ 370 Fig. 9. The System LiF-BeF,-ThF,. Table 7. Limits of Single-Phase in 3LiF+.ThF, were not to occur. 3LiF+ThF, Solid Solution* Composition in mole % This is a way of saying that when such mixtures are used as reactor fuels, the segregation of the tho- . LiF BeF, ThF, rium-containing phase or phases ! 75 0 25 from the LiF-BeF, solvent on cool- 58 16 26 ing will be less than one would 59 20 2% expect without a knowledge of the solid solution. 3 *¥R. E. Thoma (ed.), Phase Dia- R i aRREaRTE grams of Nuclear Reactor Materials, Y P ORNL-2548, p 81 (Nov. 6, 1959). formed in the system. Conse- quently, all the solid phases formed in the system, except for members of the 3LiF.ThF, solid solution, are the components or binary compounds described above (Secs 3.1, 3.2, 3.3, and 3.4). The compositions and the temperatures of the six invariant points may be found in Table 8. UNCLASSIFIED ORNL-LR-DWG 43437 ° Q Q Q (=2 % o ., b 2 N, S Q o 9 & o 5 h s © S & ; S o s ° S EXOF K (@] o/ a S S % 0 BeF,+LIQUID S A o Y b ThE, + LIQUID & € o) ¢ ThE, + BeF, = d s A d 2LiF-BeF, + BeF, - f e A\ e 2LiF-BeF,+LIQUID L e a f LiF + 2LiF-BeF, [ g LiF +LIQUID 500 / o h LiF-4ThF, + LIQUID g / TEMPERATURE IN °C /' TLiF-6Thi, + LIQUID 600 COMPOSITION IN mole % J 3LiF-ThE, ss + LIQUID k LiF-2ThF, +LIQUID 700 /' 3LiF-ThF, + LIQUID m LiF + 3LiF ThE, 800 v A 3LiF-ThE,+ 7LiF-6ThE, L 0 LiF-4ThF, + The, 565 p LiF-2ThF, + LiF - 4ThF, g TLiF-BThF,+ LiF-2ThE, Fig. 10. The System LiF-BeF,-ThF,. The equilibrium phase behavior which will occur in several selected LiF-BeF,-ThF, compositions is described in Table 9. When mixtures of LiF-BeF,-ThF, are cooled slowly from the liquid state, equilibrium is rarely, if ever, achieved. In compositions C-127, Cc-133 (or C-1lla), and BeLT-15, solids have been routinely observed in the cooled melts which are indicative of nonequilibrium cooling.®”:66 6°R. E. Thoma, Results of X-Ray Diffraction Phase Analyses of Fused Salt Mixtures, ORNL CF-58-2-59, item 1854 (Feb. 18, 1958). 66R. E. Thoma, Results of Examinations of Fused Salt Mixtures by Optical and X-Ray Diffraction Methods, ORNL CF-59-10-18, item 2095 (Oct. 7, 19597, 21 UNCLASSIFIED PHOTO 32551 Fig. 11. The System LiF-BeF,;-ThF,. UNCLASSIFIED ORNL-LR-DWG 40224 BeF, 2LiF-BeF, Flg. 12. BeF,-ThF, ¢ The System LiF- 550°C Isotherm. UNCLASSIFIED ORNL-LR-DWG 40223R ?LiF-BeF, < FPig. l4. BeF,-ThF, ¢ The System LiF- 444°C Isotherm. 22 UNCLASSIFIED ORNL~-LR-DWG 40222R LiF-4ThE, LiF-2ThF, 7LiF-6ThE, "y \ 7 LiF 2LiF-BeF, Fig. 13. Bng-ThF4 H The System LiF- 497°C Isotherm. UNCLASSIFIED ORNL-LR-DWG 40224R Thig LiF- 4TI’\F4 LiF-2The 7LIF-6ThE, 3LiF-Th, ,, ) 4 W w‘g& 4 2LiF-BeF2 LiF é— Fig. 15. BeF,-Thl : The System LiF- 433°C Isotherm. Solid-state equilibrium is readily established if the solid mixture is annealed for a short time at temperatures near the solidus. The system pairs LiF-BeF,-ThF, and LiF-BeF,-UF, are very similar. In both, the primary phase fields of the LiF-BeF, compounds occupy a small area, and the lowest liquidus temperatures are very near those in the sys- tem LiF-BeF 2 A rather low temperature region exists on the liquidus surfaces in the vicinity of 70 mole % LiF. The liquidus surfaces in the Table 8. Invariant Equilibria in the System LiF-BeF,-ThF,* Composition of Liquid Invariant (mole %) Type of Solids Present Tem€fg?ture Invariant at Invariant Point LiF BeF, ThF,, 15 83 2 497 Peritectic ThF,, LiF.4ThF,, and Bng 33.5 64 2.5 455 * Peritectic LiF-4ThF,, LiF-2ThF,, ' and BeF; 47 51.5 1.5 356 + Eutectic 2LiF-BeF,, LiF.2ThF,, and BeF, 60.5 36.5 3 433 % Peritectic LiF-2ThF,, 3LiF-.ThF,ss, and 2LiF-.BeF, 65.5 30.5 4 b4bidy Peritectic LiF, P 597 A \ £ 568 3LiF-ThF, £ 565 \ Q P 609 Alf) 2 3 O _ e ] \ 845 aLiF-ury” P500" '£490 P 610 j\ P 775 . LiF-4UF, 055 . TLIiF-6UF, : Fig. 17. The System LiF-UF,-ThF,. UNCLASSIFIED PHOTO 32550 Fig. 18. The System LiF-UF,-ThF,. 28 UNCLASSIFIED ORNL-LR-DWG 27915AR & THERMAL BREAKS © QUENCH DATA SEPARATING REGIONS (2)(4)(¢) AND (¢) 1100 THE SYMBOLS BELOW INDICATE CHANGES WITH DECREASING TEMPERATURE o (a) TO (&) ® (5) TO (¢) ®(c) TO (2) < | e (5) TO (d) (@) 1000 ] \\‘ A 3 & I(m = LIQUID + UF, — ThF, ss & 900 } s = ILIOUID+ UF, =ThFy ss + LiF+4 UF, —LiF - 4 ThF, ss ™ . s S 800 - (d) t e LiF - 4UF4 —LiF - 4ThF, ss 700 0 10 20 30 40 50 60 70 80 UF, (mole %) Fig. 19. The System LiF-UF,- ThF,: 20 Mole % LiF Section. points are listed in Table 10. The temperatures and compositions equilibrium phase behavior of a ternary system involving solid solutions can be clearly and un- ambiguously described only by an extensive series of isothermal sections, fractionation paths in the primary phase areas, and tie lines in the subsolidus regions. Four isothermal sections which il- lustrate the invariant and the subsolidus phenomena are shown in Figs. 23-26. paths for the primary phase areas The fractionation of the solutions may be found in Fig. 27. Tie lines for three of the subsolidus two-phase regions are shown in Fig. 28. of the three ternary invariant The compatibility triangles associated with these invariant points are shown in Fig. 29 and Table 10. TEMPERATURE (°C) 1100 1000 900 800 700 600 500 (@) (b) () (d) (e) (#) (g) (h) 29 UNCLASSIFIED ORNL-LR-DWG 35506R UFa — ThFs ss + LIQUID LiF - 4UF, ~ LiF - 4ThF, + LIQUID UF,—ThF, ss + LIQUID + LiF - 4UF, = LiF - 4ThF, ss LiF - 2ThF, ss + LIQUID + LiF- 4UF, — LiF - 4ThF, ss LiF - 4UF, —LiF- 4ThF, ss + LIQUID + 7LiF- 6 UFy — TLiF- 6ThF, ss ~ LiF- 2ThF, ss | ' | LiF- 4UF,—LiF - 4ThF, ss + 7LiF - 6 UF4— 7LiF - 6ThFa ss LiF - 4UFy —LiF-4ThF, ss + 7LiF - 6UF, ~7LiF - 6ThF, ss +LiF- 2ThF, ss A THERMAL BREAKS ® QUENCH RESULTS O TIE LINE INTERSECTION (@) -7 o~ ‘\ LIQUID (£) (T \ - A NQ (o) R T ——— ‘ A \ .\‘_\\ \--\‘C \\“§ (b) ' A\ (£) \}-‘ll/ (€) I (9 I |1t 0 10 20 30 a0 50 60 662, UF, (mole %) Fig. 20. The System LiF-UF4-ThF,: 33-1/3 Mole % LiF Section. TEMPERATURE (°C) 850 800 $= 700 650 {a) (b (c) (&) (6) (7) 30 LiF - 4UF, = LiF ~.4ThFy ss + LIQUID LiF - 2ThF, ss + LiF - 4UF, —LiF-- 4ThF, ss + LIQUID LiF - 2ThF, ss + LIQUID _ LifF -2ThF, ss + 7LiF - 6UF, — 7LiF - 6ThF, ss + LIQUID 7LiF - 6UF, — TLiF -6 ThF, ss + LIQUID 7LiF - 6UF,— 7LiF - 6 ThF, ss UNCLASSIFIED ORNL-LR-DWG 27917AR A THERMAL BREAKS ® QUENCH RESULTS © TIE LINE INTERSECTION LIdUID (@) () Fig. 21. The System LiF-UF,-ThF,: 53.8 Mole % LiF Section. 20 25 UFy (mole %) 30 35 " 40 45 46.2 o Fig. 22. The System LiF-UF,-ThF,: TEMPERATURE (°C) 575 550 525 500 475 450 31 UNCLASSIFIED ORNL-LR-DWG 35503R LIQUID + 3LiF ThF, ss LiF+ LIQUID LiF + 3LiF - ThF, ss + LIQUID LiF + 7LiF - 6 Thf, — 7LiF - 6UF, ss + LIQUID 4LiF-UF, + LIQUID + LiF 4LiF - UF, + LIQUID 4LiF-UF, + 7LiF-6ThF, —7LiF-6UF, ss + LIQUID 3LiF- ThFy ss 3LiF - ThF, ss + 7LiF - 6 ThF, — 7LiF - 6UF, ss + LiF LiF + 7LiF - 6 ThFy— 7LiF - 6 UF, ss LiF + 4LiF -UF, + 7LiF -6 ThF, — 7LiF - 6 UF,; ss 4 LiF - UF, + 7LiF - 6 ThF, — 7LiF - 6 UF, ss T i A THERMAL DATA ® QUENCH DATA p - v:\ . O TIE LINE DATA < LIQuUID (c) (M / () ® (d) 1 (Y2 VA IS ) Vo™ AN o (6] 10 15 20 UF, (mole %) 25 75 Mole % LiF Section. 32 UNCLASSIFIED ORNL—LR—DWG 35742 a {a} CONTAINS: 1) LiF- 4 ThE,— Lif- 4UFy ss 2} LiF - 2ThF,ss 3) 7LiF- 6 ThF, — 7 LiF- 6UFss 4) LIQUID LiF - 4ThF, ’ Y t L ] o. _ . (’-i\ . ¥ N ) LiF -2ThE, AL ’. <. 44\ [ 0 e N ¥ . ' . \ L) =4 e © . A % .. ’;X 4('\ .. z\;\ O. g\ po .. P\ \o v o)) (gfi '.“{'s\ ;‘\{}\ o (,‘qp% . a . 7 % » ‘ D x Za % /// . =S % Te %S W e /” 4 . /! .o [ ] By > /s 7/ ¢ . /7 = . /7 7 < it Y o, % VA ) e /s 7 A * 'y { ?(\P\ [ ,’l,/“o. P\A (’.&\ o. \ X A% <. @ % (6('*"43 % G % LIQUID X & %, . . C.’«‘“'o . fal % LiF v\ e o . ') [ ] + ¢ % % _LIQUID . LF v, \/ VARRCOURY, \/ \/ LY V uF, 7LiF -6 UF, ' Lif - 4UF, Fig. 23. The System LiF-UF,-ThF,: 609°C Isothermal Section. & 33 UNCLASSIFIED ORNL—LR—DWG 357414R TLIF-6Thfy £ (@) CONTAINS: 1) TLiF- 6UF; — 7TLiF- 6ThF;ss 2) 3LiF- ThF, ss 3) LiF 4) LI1QUID (5} CONTAINS: 1) 7LIF- BUF, — 7LiF - 6 ThF, ss 2) LiF- 4UF4—LiF-4ThF455 3} LiF- 2 ThF,ss 3LiF-ThF ss + SLIF-Thf, 7LiF - BUF, —7LiF - 6ThF, ss . LiF + 3 LiF - ThF4 5S Pt e LiouiD + . PP b Oy TUF-BUE — R Pt LiF + LIQUID C. TLiF- 6ThF,ss % T /’:”’ © .. %\ - - Y LiF L2V \/ v AV \/ v Y V VAN 7LiF- BUF, Fig. 24. The System LiF-UF,-ThF,: 500°C Isothermal Section. 34 UNCLASSIFIED ORNL —LR—DWG 35738 (6) CONTAINS: 1) 7LiF+ 6UF, — 7LiF- 6 ThF,ss 2) 4LiF- UF, 3) LiF 4) LIQUID () CONTAINS: 1) TLiF - 6UF, —7LiF-6ThF, ss 2) LiF - QUF, —LiF- 4 ThF, ss - 3) LiF- 2 ThRyss ' | 3LIF-ThE, ss + e 7LiF BUFy — 7 LiF- 6ThF, 55 LiF + . . 3LiF - ThF, . ———TT - Thigss %o e - . S —— - . 'éfi //‘ ”’ . .. P.s\ -7 BLIF-Thigss + -~ o5 - g TLIF-6UF, — ”,— . CA;‘\ L7 TLiF -6 Thf 55 -~ O LiIF+ . L77 HUF -7 TLIF-6UR — TLIF - 6ThE,ss % 4 LiF - UF, Fig. 25. The System LiF-UF,;-ThF,: 488°C Isothermal Section. # 35 UNCLASSIFIED ORNL—LR—DWG 35739 ThF, {g) CONTAINS: 1) LiF- 4UF, —LiF - 4ThF, ss 2) 7 LiF-8UF, — 7TLiF- 6 ThF, ss 3) LiF- 2ThE, {L) CONTAINS: 1} 7Lil- GUFZ — 7 LiF: GTth L1 2} 3LiF- ThE, ss 3) LifF {c) CONTAINS: 1) 3LiF - ThF, ss 2} LiF [ ] 3LiF- ThF,ss*, , 2N ) +7LIF-BUF, =%, 4 IR o —— - LiF + . % P [ ] [ o LR BU = /L b ing s S, ", - L N - I/,’/ A o. I’ . LiF \/ Vi \/ v v Vi v °/ Vi U, 7 LiF - 6UF, LiF -4UF, Fig. 26. The System LiF-UF,-ThF,: 450°C Isothermal Section. 36 UNCLASSIFIED ORNL-LR-DWG 358505R ThF, LiF - 4ThF, LiF-2ThF, : P P // _ \\94 / . 2 \/ ‘g‘, >-45\/ \/ N, \/ aLIF-UE, PE P TLIF-BURy LiF: QUF, LiF UF, Fig. 27. The System LiF-UF,-ThF,: Fractionation Paths. A L1 37 UNCLASSIFIED ORNL—LR—0OWG 35740R 50% ThF, 7LiF-6ThF, ® PHASE COMPOSITION. 4 QUENCH COMPOSITION 3LiF - ThF, - — - -—— 4 Lif - UF, _ — UF, 7LiF-6UFR, Fig. 28. The System LiF-UF,-ThF,: Tie Lines. 38 - Table 10. Invariant Equilibria in the System LiF-UF,-ThF,* Composition of Invariant Point Invariént . Type Solid Phases . . C in Equilibrium (mole. %) ' '-Tempfrature O? . at the Invariant (°c) Equilibrium Temperature LiF UF, ThF, - | 63 19 18 - 609 Peritectic LiF«4ThF,-LiF-4UF,ss ' . containing 28 mole % UF,, - LiF-2Th(U)F ss containing 23 mole % UF,, 7LiF<6ThF,- 7LiF.6UF,ss con- taining 23 mole % 4 UF,; . 72.5 20.5 7 500 Peritectic 7LiF+6ThF,, - - . o o 7LiF.-6UF,ss contain- ing 31 mole % UF,, 3LiF-Th(U)F,ss con- taining 15.5 mole % UF,, LiF | 72 26.5 1.5 488 . Eutectic 7LiF +6ThF, -~ | | 7LiF-6UF,ss contain- ing 42.5 mole % UF,, LLiF-UF,, LiF *C. F. Weaver et al., Phase Equilibria in the Systems UF,-ThF, and LiF-UF4-ThF,, ORNL-2719 (Aug. 17, 1959); J. Am. Ceram. Soc. 43, 213 (1960). 39 UNCLASSIFIED ORNL-LR-0WG 35504 Thf, LiF - 4ThF,, LiF - 2ThF, 7LiF - 6ThF, ——609°C 3LiF . ThF4 (c) LiF 4LiF - UF, 7LiF - 6UF, LiF- qUF, UF, Fig. 29. The System LiF-UF,-ThF,: Compatibility Triangles. 3.11 The System LiF-BeF,-UF,-ThF, (Selected Portions) Detailed phase equilibrium studies for an entire quaternary system require such a vast amount of time and money that they aré usually cuuw- pleted over a number of years if at all. The system LiF-BeF,-UF,-ThF, is no exception in this respect, and consequently the experimental work was directed toward compositions which posses sufficiently low liquidus and viscosity values to be of project interest. The similarities between the systems BeF,;-ThF, and BeF,-UF,, the systems LiF-ThF, and LiF-UF,, and the systems LiF-BeF,-''nt, and LiF-BeF,- UF, have been discussed in Secs 3.2, 3.5, and 3.8 of this report. Within the systems 1JF,-ThF, and Li¥F-UF,-ThF, extensive solid solutions are formed between corresponding compounds. The existence of these similar systems and of solid solutions between analogous compounds leads to the hypothesis 40 that UF, and ThF, are very nearly interchangeable in the quaternary mix- turestwith respect to their liquidus values and that the phase relation- ships in the quaférfiary system will be very much like those in the ternary systems LiF-BeF,-ThF, and LiF-BeF,-UF,. Four sections of constant mole | per cent LiF and BeF, were studied experimentally as a means of partially N verifying this hypothesis. These sections contain 70 LiF and 10 BeF,, 67.5 LiF and 17.5 BeF,, 70 LiF and 6 BeF,, and 65 LiF and 25 BeF, (mole %). The first two sections include the compositions C-136 and BeLT-15 (see Appendix C). The experimental results of these experiments may be found in Table 11. The liquidus values along the first three joins are nearly linear functions of the composition (Figs. 30-32). The deviation from linearity in the fourth join (Fig. 33) is in the direction of lower liquidusttemperaturesL The ThF,-containing end member has the maximum liquidus temperature for all the joins, while the UF,-containing end member has the minimum liquidus temperature for three of the four joins. The solid solution 7LiF+6(U,Th)F, is the primary phase for all the com- positions on the joins listed above. The interchangeability of UF, and ThF, implies that a breeder blanket selected from the quatérnary.system or its limiting systems will contain the maximum concentration of ThF, for a given temperature only if no UF, is present. 1In other'words; if UF, is added an approximately equal amount of ThF, must be removed to maintain the same liquidus temperature. ' Mixtures containing a maximum amount of ThF, for a given temperature are found in the system LiF-BeF,-ThF, (Figs. 9%-11) up to 568°C. Above 568° the mixtures must contain no BeF,; thus they will be binary mixtures of LiF and ThF,. : - | The members.of a second series contain a small total mole percentage of UF, and ThF, (Table 11). They represent the breeder fuels, such as C-134, BULT 4-0.5U, and BULT 4-1U. Cdmpositions containing up to 5 mole - % UF, + ThF, in the range 30-38 mole % BeF, have 1iquidus values close to those. of the system LiF-BeF,. These compositions differ from the LiF- = ‘Bng binary mixtures in that their liquidus values are slightly lower and solid solutions containing UF,; and ThF, precipitate as primary or Table 11. Thermal Gradient Quench Data for the System LiF-BeF,-UF,-ThF, Composition a (mole %) : Tem?fg?ture Phasesb Above Temperature Phasesb Below Temperature LiF BeF's UF4 ThF4 55 35 3 7 427 + 3 LS and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and 2LiF -BeF, 56 35 2 7 432 *+ 3 L and 7LiF-6(U,Th)F,ss L, 7LiF+6(U,Th)F,;ss, and 2LiF -BeF, 57 35 3 5 488 + L L and LiF-2ThF,ss 57 35 3 5 480 * L and LiF-2ThF,ss L and 7LiF.6(U,Th)F,ss 57 35 3 5 433 L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and | 2LiF -BeF, 58 35 2 5 498 + 3 L L and LiF-2ThF,ss (15 mole | % UF,) 58 35 2 5 460 + 2 L and LiF.2ThF.ss 'L and 7LiF-6(U,Th)Fsss (11 ' mole % UF,) 58 35 2 5 433 £ 3 L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and 2LiF-BeF2 59 35 3 3 479 + 2 L L and 7LiF.6(U,Th)F,ss (22 mole % UF.) 59 35 3. 3 434 £ 2 L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and 2LiF-BeF2 60 35 2 3 449 + 2 L L and 7LiF.6(U,Th)F,ss 60 35 2. 3 440 * L and 7LiF.6(U,Th)F,ss L, 7LiF-6{U,Th)F,ss, and 2LiF-BeF, 60 35 2 3 ~425 L, 7LiF-6(U,Th)F;ss, and 2LiF.BeF, and 2LiF-BeF, 7LiF-6(U,Th)F,ss (20 mole % UF,) 17 Table 11 .(continued) Composition a . ) . . (mole %) Tem%igjfiure A Phasesb Above Temperature ‘Phasesb-Bele Temperature LiF BeF, UF; ThF, 60 36 3 1 449 + L . L and 7LiF.6(U,Th)F,ss 60 36 3 1 432 * L and 7LiF+6(U,Th)F,ss L, 2LiF-BeF,, and o ‘ _ - 7LiF-6(U,Th)F, 60 37 2 1 - 434 * L L and 7LiF+6(U,Th)F;ss - - 60 37 - 2 1 431 * L and 7LiF+6(U,Th)F,ss L, 7LiF+6(U,Th)F,;ss, and " , - : S 2LiF.BeF, 60 38 442+ L . | L and 2LiF.BeF, 60 38 1 1 433 %2 I and 2LiF-BeF, L, 2LiF+BeF,, and | : . : 7LiF+6(U,Th)F,ss (20 mole | | b UF,) 61 36 2 1 437 2 L - L and 2LiF-BeF, 61 36 2 1 434 + 2 L and 2LiF-BeF, L, 2LiF-BeF,, and ‘ ' ' - 7LiF-6(U,Th)F,ss (23 mole . : % UF,) | 61 37.5 0.5 1 439 + 3 L I and 2LiF-BeF, 62 34 3 1 446 * 2 . . L and 7LiF.6(U,Th)F,ss 62. 34 -3 1 443 % L and 7LiF-6(U,Th)F,ss L, 7LiF+6(U,Th)F,ss, and . . . 2LiF°BeF2 ' 62 36 . 1. 1 446 + 2 L L and 2LiF Several investigations of | < S y A _ ) the interaction of molten mix- tures of LiF, BeF,, UF,, and ThF4 found in the ORNL literature. | | . ! . . . /' . ! with other substances may be 12.0 ‘ ' i | B 5 w0 1’ 25 30 35 40 45 The. solubility of CeF3’' in o LiF-BeF,-UF,-ThF, liquids and the . Fig. 35. Hydration—Vacuum-Dehy- reactions of Be07? and steam on dration Cycle for LiF-BeF,-~ThF,-UF, (62-36.5-1-0.5). these solvents have been reported. _ The exchange of CeF; (dissolved in a quaternary solvent) and LaFs; (solid) has been studied.’® The segre- 60 gation effect of thermal cycling,®® graphite compatibility,®? and the 1eaching of chromium from INOR-872 have been investigated. 4. ACKNOWLEDGMENTS It is a pleasure to acknowledge the assistance of G. M. Hebert, who prepared a number of the quenched samples. We are especially grateful to J. H. Burns, F. F. Blankenship, H. G. MacPherson, and J. E. Ricci for " suggestions and advice concerning many phases of the investigation. 7!R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep: Jan. 31, 1960 ORNL-2931, p 79. 72J. H. Shaffer, G. M. Watson, and W. R. Grlmes, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931, p 86. _ 735, E. Eorgan et al., Reactor Chem. Ann. Prog. Rep. Jan. 31 1960, ORNL-2931, p 67.. . N Appendix A 51 OPTICAL AND CRYSTALLOGRAPHIC PROPERTIES The optical and crystallographic properties of the compounds which occur in the system LiF-UF,-ThF,-BeF, are summarized in Tables A-1 and A-2 respectively. No. ternary or quaternary compounds have been observed. The refractive indices of the LiF-UF,-ThF, and UF,-Th¥, solid solutions may be found in Figs. Table A-1. A-1 through A-5. Optical Properties of the Components and Binary Compounds in the System LiF-UF,-1hF,-BeF, Optiéal Optic Optic Refractive Indices Compound Character Angle, Sign : Color 2V Nw or Na N€ or Ny LiF Isotropic 1.3915 Colorless BeF> Uniaxial + 1.325 Colorless UF,° Biaxial ~60° —~ 1.552 1.598 Green ThF4b Biaxial ~60° — 1.500 1.534 Colorless 2LiF-BeF,’ Uniaxial + 1.312 1.319 Colorless LiF-BeF; Biaxial Large 1.35 (average) Colorless 4LiF-UF4b Biaxial ~10° — 1.560 1.472 Green 7LiF-6UF,° Uniaxial — 1.554 1.551 Green LiFoAUF4b Biaxial ~10° — 1.584 1.600 Green 3LiF°ThF4d’e Biaxial ~10° — 1.480 1.488 Colorless ’7LiF'6'I‘hF4d Uniaxial + 1.502 1.508 Colorless L1F-2ThF4d Ufiiaxial - 1.554 1.548 Colorless LlF-4ThF4d’e Biaxial ~10° - 1.528 1.538 Colorless “Am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 4-0857. bH. Insley et al., Optical Properties and X-Ray Diffraction Data for Some Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct. 23, 1956). °W. W. Harris and R. A. Wolters, Optical Properties of UF,, MDDC-1662 (Nov. 5, 1947); USAEC, Abstracts of Declassified Documents, vol 2, p 103 Techni- cal Information Div., Oak Ridge, dR. E. Thoma EE al., J. Phys. Tenn., 1948. Chem. 63, 1266 (1959). ©This routinely observed biaxialifiy appears to be a function of strain, since the crystal type is tetragonal as determined by x-ray diffraction measurements (see Table A-2). Table A-2. (Crystallographic Properties of the Components and the Binary Compounds Which Occur in the System LiF-UF,-ThF,-BeF; Lattice Parameters X-Ray Compound g;zizzl Space Group Density ag (A) bo (A) co (A) B (g/cc) LiF® © Cubic (face- 4.0270 0’-Fm3m 2.638 o centered) ’ ' BeFéb S Hexagonal 4.72 5.18 : D¢ = C6,2, ' DI = C6,2 ThrF,° Monoclinic 13.1 11.0L 8.6 126° 5, -c2/ec - 5.71 U’Fg,c’d Monoclinic 12.82 - 10.74 8.41 126°10" Cgh-C2/c _ 6.70 7LiF-6UF,° Tetragonal 10.48 | | 5.98 T4y /a 3LiF-’I‘hF4f Tetragonal 6.206 6.470 P4/nmm or P4/n 5.143 '7LiF-6ThF4f Tetragonal 15.10 6.60 | T4, /a | 5.387 LiF'ZThF4f Tetragonal 11.307 6.399 Body-centered(?) LiF-4ThF4f - Tetragonal 12.984 . 11.46 - 2LiF-BeF,® Hexagonal 13.23 8.87 ) “Am. Soc. Testing Materials, X-Ray lefractlon Data Cards, card No. 4-0857; H. E. Swanson and E. Tatge, J C Fel Reports, NBS 1949. A bThlS is the B-quartz form of BeF, routinely observed in the systems described in this report. . The B- quartz and three other forms of BeF, are.described by A. V. Novoselova, Uspekhi Khim 27, 33 (1959). w H. Zacharlasen, Acta Cryst. 2, 388 (1949). Am Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 8-428. L A. Harris, The Crystal Structures of 7:6 Type Compounds of Alkali Fluorldes with Uranium Tetrafluoride, ORNL CF-58-3-15 (Mar. 6, 1958). fL, A. Harris, G. D. White, and R. E. Thoma, J. Phys. Chem. 63, 1974 (1959) €am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 6-0557; E. Thilo and H. A. Lehmann, Z. anorg: Chem. 258, 332 (1949). (4 UNCLASSIFIED ORNL—LR—DWG 27944R 1.62 1.60 —— = // ‘ 3 1.58 " = L Q / E 1.56 /, w | (¢4 | "] % 154 — / ;’/ x ,/ ‘é 152 P = / ’/‘ 150 "] 148 THE, 20 40 60 80 UF, UR, (mole %) Fig. A-1. Refractive Indices of the UF,-ThF, Solid Solutions. 53 UNCLASSIFIED ORNL-LR-DWG 27916R 1.62 1.60 b4 2 A O 1.58 I R T T 156 > w ' (T © —"SCd INDEX OF & ,//‘,o’/‘ T REFRACTION 2 1.54 o Z v [ 1.52. 1.50 0 0 20 30 40 S0 60 70 80 UF, (mole %) Fig. A-2. Refractive Indices of the LiFo4UF4-LiF-4ThF4 Solid So- lutions. UNCLASSIFIED ORNL-LR-DWG 35507R 1.57 N, =ORDINARY INDEX OF REFRACTION 1.56 //( " Q | | /‘1 O ~ INDEX OF REFRACTION %) o N =EXTRAORDINARY INDEX OF REFRACTION PROBABLE LIMIT OF EXISTENCE FOR 1iF- 2ThFg ss ) IS 1.53 15 20 29 a0 - UF; (mole %) Fig. A-3. Refractive Indices of the LiF-2Th(U)F, Solid Solutions. 54 UNCLASSIFIED UNCLASSIFIED -l R~ ORNL-LR-DWG 312t7R2 1.62 - ORN.L LR-DWG 279{8R2 1.540 1.60 2 1.530 = S 1.58 x - . N, =ORDINARY INDEX OF REFRACTION<' z wi N, =EXTRAORDINARY [NDEX OF REFRACTION\ Q 1.520 MAXIMUM EXTENT OF x 1.56 3 5 3LiF- ThF, o S = p SOLID sownon—-l x w ! w 1,54 ‘ & 1.510 f 8 T A i - A ) .—0'/¢ © / 1.52 /‘,//I - 5 1.500 c‘(\ON / | ) < RS cFRM * " . = % of RET : /0 1501 | y WoE _— | 0 "5 10 .15 20 25 30, 35 40 45 490 - Efauc“°§*“ ! o ' P R | UF4 (mO'e o) ) . ] \NDE‘L Offi/ | Fig. A-4. Refractive Indices 1-480¢ 5 5 é Of the 7L1F 6IJF4"7L1F 6ThF4 SOlld UF4 CONTENT {mole %) Solutions. Fig. A-5. Refractive Indices of the 3LiF.Th(U)F, Solid Solu- tions. Appendix.B X-RAY DIFFRACTION DATA FOR THE SOLID PHASES OBSERVED IN- THE- QUATERNARY SYSTEM LiF-BeF,-UF,~ThF, . LiF> | ThF,, ThF, (continued) Bngb a (A) I/11 a4 (a) I/Iy a (a) I/13 7.63 10 2.528 12 . 5.24 10 2.495 12 4 .09 - 70 4.75 20 | 2.361 5 3.21 100 4 46 12 2.350 10 2.367 100 4.29 20 | 2.338 10 2.189 - 100 - 4.02 60 2.259 5 2.154 100 © 3.80 100 2.242 5 1.905 70 3.72 5 2.196 5 1.748 50 3,63 - 50 2.156 15 1.606 35 3.43 ' 15 2.132 35 1.591 20 3.35 50 2.113 - 35 1.550 30 3.04 5 2.067 5 1.484 30 2.848 5 2.040 20 1.320 30 2.796 5 2.023 20 1.233 15 2.747 15 . 1.985 . 35 1.208 15 2.723 .5 1.965 15 - ' 2.629 5 | 1.937 .15 UF, o 1.922 25 (s ¥ 55 Appendix B (continued) ThF, (continued) 3LiF-UF4b - 7LiF-6UF4b (metastable) (continued) a (a) 1/1, a (A) I/I,1 a (A) I/I, 1.881 10 1.859 - 5. 4 .98 20 3.33 90 1.771 10 4% .80 15 3.15 70 1.737 10 4 41 100 3.07 10 1.683 20 4 .34 100 2.99 95 - 1.666 10 3.98 15 2.771 30 1.640 10 3.91 8 2.707 30 1.612 10 3.60 80 2 .542 25 1.588 5 3.40 10 2.350 13 1.575 10 3.14 25 2.286 25 .1.520 20 3.07 50 2.264 13 1.484 5 2.84 80 2.184 10 1.455 20 2.771 30 2.097 30 1.431 10 2.529 35 2.060 30 1. 404 5 2.169 15 2.047 75 1.373 10 2.083 75 1.993 25 _ o 2.055 35 1.972 20 4LIiF-UF, 1.943 50 1.947 25 1.913 - 25 1.924 15 a (a) 1/1, 1.861 30 1.909 30 1.751 25 1.854 45 5.67 20 1.723 25 1.825 20 5.46 25 1.685 25 1.773 20 5.13 70 1.662 8 1.757 25 4.93 100 1.646 20 1.709 15 4 .55 45 1.599 8 1.680 15 A 100 1.625 15 4 .23 7 7LiF-6UF,, 1.579 25 3.82 40 : 1.562 8 3.55 30 a (A) 1/1, = 3.03 50 LiF-4UF, 2.89 25 6.61 6 2.866 30 5.97 20 a (a) I/1, 2.747 50 5.82 15 2.468 40 5.24 90 7.02 8 2.398 20 5.15 10 6.33 12 2.221 40 4.65 10 6.07 5 2.107 75 4 .37 13 5.73 25 2.07% 20 3,95 55 4.98 8 2.025 20 3.85 13 4.70 25 1.872 20 3.68 20 .25 90 1.836 25 3.49 75 3.88 20 56 Appendix B (continued) LiF-4UF4b4 3LiF-ThF4d ‘(continued) (continued) da (A) I/1, da (a) I/I1 3.78 100 1.701 35 3.52 90 1.661 10 3.16 8 1.618 10 3.13 8 1.547 35 3.06 12 1.520 35 2.84 40 g:zzg 52 7LiF‘6ThF4d 2.350 10 2.310 10° a (a) 1/1, 2.226 8 2.000 10 6.07 15 2.088 35 5.91 20 2.016 60 5.36 90 1.991 50 5.25 15 1.888 20 4 .95 30 1.819 8 .85 . 20 1.767 25 475 100 - T 4.01 85 3LiF-ThF, 3.92 15 —— ‘ 3.74 15 a (a) I/1, 3.55 65 ' - . 3.44 10 6.42 100 3.39 70 4.6 100 3.29 60 4,37 100 3.03 100 3.62 85 2.814 25 3.09 55 2.747 25 2.866 70 2.578 20 2.788 30 2.430 10 2.542 25 2.392 10 2.327 10 2.302 20 2.189 20 2.137 20 2.104 65 2.018 5 1 2.071 25 2.001 15 2.036 40 1.892 55 1.959 30 1.859 15 1.933 .- .60 1.804 15 1.877 .25 1.680 15 1.771 25 1.653 20 1.743 30 1.600 20 LiF°2ThF4d da (A) 1/1, 7.97 5 6.37 10 3.96 100 3.57 65 3.25 5 3.21 5 2.97 20 2.822 25 2.675 7 2-.528 10 2.388 5 2.123 85 2.053 "~ 30 2.001 65 1.787 7 1.701 10 1.689 5 1.603 5 1.519 5 LiF°4ThF4d a (A) I1/1, 8.34 3 7.76 3 6.51 5 5.80 25 4 .62 5 4.33 70 3.88 100 3.60 60 3.25 10 2.92 25 2.822 25 2.603 10 2.398 10 2.137 25 2.053 35 2.040 10 2.018 10 2.005 30 y— _Appendix B (continued) LiF-4Thr, LiF.BeF,T LiF-BeF,~ (continued) (continued) a () - 1n - h ¢ (0 I/12 1.937 .20 4.353 20 2.040 20 1.820 20 3 .;1.80 50 1.829 10 1.778 3 3.084 30 1.691 10 1.725 5 2.926 20 1.558 - 5 1.719 5 2.836 5 1.488 2 1.666 5 2.780 50 1.439 2 1.605 5 2.739 10 1.324 10 1.595 5 2.455 40 1.303 1 1.563 5 2.259 50 1.244 2 2.201 100 - 1.233 1 2LiF . Bng € 2 .074 80 . 1. 216 2 “Am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 4"0857 . : bH. Insley et al., Optical Properties and X-Ray Diffraction Data. for Some Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct. 23, 1956). cAm.ASoc. Testing Materials, X-Ray Diffraction Data Cards, card No. 8-428. . E. Thoma et al., J. Phys. Chem. 63, 1266 (1959). 'eAm. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 6-0557. fg. Thilo and H. A. Lehmann, Z. anorg. Chem. 258, 332-55 (1949). ~ Appendix C 58 ; LIQUIDUS TEMPERATURES AND PRIMARY PHASES FOR SPECIFIC COMPOSITIONS FULL 73 73 27 Composition Liquidus (mole %) TquLed Primary Phase Code Temperature . . (°C) or Phases LiF BeF2 U-Fz, ThF4 C-9 .. 100 548 BeF, c-10 100 845 LiF C-74 69 31 530 LiF C-75 67 30.5 2.5 464 LiF C-111 71 16 1 12 505 3LiF+ThF,ss c-112 50 50 370 2LiF «BeF, C-126 53 46 1 400 2LiF-BeFs c-127 58 35 7 460 LiF.2ThF, c-128 71 29 568% 3LiF