M [EMS LIBRA [TTATNT 3 445k 03kL181 1 CENTRAL RESEARCH LIBRARY DOCUMENT COLLECTION LIBRARY LOAN COPY DO NOT TRANSFER TO ANOTHER PERSON If you wish somecne else to see this document, send in name with document and the librory will arrange a loan. ORNL-2353 C-84 — Reactors-Special Features of Aircraft Reactors This document consists of 22 pages. Ct:bpy/a?}Z of 273 copies. Series A. Contract No, W-7405-eng-26 SHIELD PLUG ASSEMBLY FOR THE ART FUEL PUMPS J. P. Page J. H. Coobs DATE ISSUED APR 2 - 1958 OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee operated by UNION CARBIDE CORPORATION for the U.S. ATOMIC ENERGY COMMISSION Wi TED 3 4456 D3L11LABL L CONTENTS ADSIEACT «nteeeetieeet et e st evee et eeneeteent sesesbebesbasaessarsabeatessans e st s aan e R e R e R e R Re et e b s S as b e R e e s R e e e easeaesr e a s R e R aasrasaeses 1 [EPOAUCEION 11veeveeeeeeeeeeeeee ettt etesesbbese s b assasseases saeesane s s easeseee s eabe et e st e e mtenbee Shbe e b eabbssbea bt bbb a bbb o bt s s b b e besab e st ansnis 1 Shield Plug Design and Materials Specifications ..........cooeviimeimiiiinii 1 Development and Evaluation of Materials and Fabrication of Parts......coccoiiiinn, 4 SUMMGIY <.ooovetieirieeeere e et es e b b e s e e s s b e b e b b e b ee s e e E e 04RS00 8 S 4 e bR e s e e e e s b b e bbb s b e b e bbb ke ke b et s e n b 9 ACKNOWIEAGMENTS ...ueiieiiccee e e bbb e e b bbbt e 10 Appendix A. Density and Conductivity Caleulations ........cccoevriinniniiciiireinicce e 11 Appendix B. Thermal Conductivity Determination Apparatus.........ccccovvviiicnnnninccninncennnneeesersenen. 14 thugr 1Ry SHIELD PLUG ASSEMBLY FOR THE ART FUEL PUMPS J. P. Page'! J. H. Coobs ABSTRACT The shield plug assembly must protect the Aircraft Reactor Test fuel pump motors from gamma and neutron radiation. It must also exhibit limited heat transfer properties. After an evaluation was made of their metallurgical and physical properties, the materials tungsten carbide ~Hastel- loy C (cermet), low-density stabilized zirconia, and stainless-steel-clad copper—boron carbide were selected for use as gamma, thermal, and neutron shielding components, respectively. A full- size assembly was fabricoted. INTRODUCTION One of several unique components of the Aircraft Reactor Test (ART) is the shield plug assembly, Two assemblies will be used in the reactor, one for each fuel pump. The location of one of the assemblies is shown in Fig. 1. The shield plug has three functions: the fuel pump motors from gamma radiation, attenuates stray neutrons, and limits the heat transfer. At full reactor power the heat developed by gamma-ray and neutron absorption must be dissipated, but at zero-power operation the lower face of the shield plug must not cool below the freezing point of the liquid fuel. Such freezing would cause fouling of the impellers. Only the materials-development aspects of the shield plug assembly are discussed. Heat transfer calculations and design detailing were performed by members of the Experimental Engineering Design Group. The gamma- and neutron-shielding specifi- cations were established by the Power Plant Engineering Section. protects SHIELD PLUG DESIGN AND MATERIALS SPECIFICATIONS An exploded view of the shield plug assembly is presented in Fig. 2. This design was arrived at after close and continued cooperation between representatives of the Metallurgy Division and members of the Experimental Engineering Design Group. 'Present address: Wright Air Development Center, Dayton, Ohie. The fabricated assembly consists of a gamma shield, a thermal shield, a neutron shield, and four Inconel-clad Chromel-Alumei thermocouples, all canned in an Inconel container, The upper surface of the container is a heat exchanger through which a noncracking oil is circulated. The gamma shield is brazed directly to the face of the heat exchanger, The specifications for the gamma-shield material are as follows: 1. density of at least 12.0 g/cm?, 2, thermal conductivity not greater than 0.10 cal/em+sec-°C, 3. structural integrity to at least 1500°F, 4. reasonable thermal-shock resistance, 5. brazeability to Inconel. The thermal and neutron shields are below the gamma shield and rest on the lower face of the Inconel can. The thermal-shield specifications called for a refractory material having a thermal conductivity as low as possible and having ade- quate strength for machining and handling. The neutron shield had to have a minimum B'® content of 0.01 g per square centimeter of the exposed face. Thermocouples, located in grooves cut in the upper and lower faces of the thermal shield, measure the temperature drop through this piece. In order for there to be no gamma leakage, the thermocouples run from the thermal shield through helical grooves cut in the gamma shield to the exit hole, which is near the top of the can. The lower face of the shield plug assembly will be exposed to temperatures of 1400 to 1500°F, while IS, PHOTO 27375 SHIELD PLUG Fig. 1. Cross Section of the Aircraft Reactor Test, Showing Shield Plug Assembly. COOLANT OUT GAMMA SHIELD p=12.09/cm3 k = 0.10 cal/cm-sec-°C THERMAL SHIELD — k, AS LOW AS POSSIBLE (. NEUTRON SHIELD | ”."HHY I B!'C CONTENT > 0,01 g/cm? LOWER CAN UNCLASSIFIED ORNL-LR-DWG 15073 T COOLANT IN PPER CAN BRAZED TO UPPER CAN ] THERMOCOUPLES PR %f.“-”’-fir.rfifiiiflnflu’ )fifiw S { 0 1 2 3 4 SCALE IN INCHES Fig. 2. Exploded View of the Shield Plug Assembly. (Confidential with caption) the temperature of the heat exchanger will never exceed 250°F, The design is especially attractive in at least three respects: as much as possible, the functions of the shield plug have been separated, permitting the imposition of a minimum number of require- ments per component; the weight of the dense gamma shield is entirely supported at the coolest part of the assembly; and the use of a canned assembly eliminates the consideration of oxidation and corrosion resistance, although high-temperature compatibilities of the various materials of interest were kept in mind throughout the development program, DEVELOPMENT AND EVALUATION OF MATERIALS AND FABRICATION OF PARTS Development of materials for the three com- ponents, which was performed semiconcurrently, is described below, Gamma Shield A review of the literature and correspondence with several industrial organizations indicated that no existing material had the unusual properties required of the gamma-shield material. Since an optimization of two nonrelated physical properties {density and thermal conductivity) was desired, rather than conventional alloy-development techniques were employed. In order to limit the scope of the investigation, only two-component systems were considered; one of these components was to be a high-density material of fairly low conductivity which would be dispersed in the second component, a very low- conductivity matrix. The gamma shield, being a hollow, right circular cylinder approximately 4 in. powder-metallurgical high by 6 in. in outside diameter by 2‘/2 in, in inside diameter, could probably be fabricated in one piece by conventional hot-pressing techniques, From density, availability, cost, and thermal conductivity considerations the materials tungsten, tungsten carbide, and tantalum were tentatively chosen as possible high-density components; tungsten, because of its relatively high thermal conductivity, was considered to be the least desirable of the three materials. Selected properties of these materials are presented in Table 1. In the search for a low-conductivity matrix material, it became apparent immediately that some member of the nickel-base family of alloys might be suitable. Nickel-base alioys, in general, have solidus temperatures in a range favorable for hot- pressing, yet retain their strengths to high tem- peratures, are fairly dense (approximately 9 g/cm3), have the lowest thermal conductivities of all the commercial alloys, and are very likely to be amenable to brazing. These alloys, however, react extensively with both tungsten and tantalum at elevated temperatures. Also, nickel reacts with graphite (which, as will be described, is the material used for hot-pressing dies) at 1322°C to form a eutectic composition, Hastelloy B, with a density of 9.24 g/cm® and a thermal conductivity of 0.027 cal/cmesec:“C, appeared to be the most promising matrix material. Unfortunately, this alloy is not available in powder form, Hastelloy C has the slightly lower density of 8.94 g/cm? and the slightly higher thermai con- ductivity of 0.030 cal/cm-sec:°C but is available in powder form at the reasonable cost of approxi- mately $5 per pound. The alloy constantan (45% Ni-55% Cu), with a re- ported thermal conductivity of 0.055 cal/cm+sec:°C, Table 1. Selected Properties of Tungsten, Tungsten Carbide, and Tantalum Material Densi;y Thermal Conductivity Approximate Cost {g/em”) (cal/cmesecs°C) ($/1b) Tungsten 19.2 0.394 12 Tungsten carbide 15.6 0.17* 5 Tantalum 16.6 0.13 56 *Estimated by the Wiedemann-Franz relationship. The electric conductivity of tungsten carbide is reported (P.Schwarzkopf and R, Kieffer, Refractory Hard Metals, p 161, Macmillan, New York, 1953) to be 40% of that of pure tungsten. For lack of better data, the thermal conductivity was assumed ta be 40% of that of pure tungsten. also appeared to be attractive. It has been shown? that copper and nickel powders alloy readily at elevated temperature by solid-state diffusion, Copper and nickel powders were on hand for test- ing, and it was felt that a relatively homogeneous alloy could be produced during the hot-pressing operation, The choice of matrix, then, was between Hastel- loy C and constantan. Selected properties of these metals are presented in Table 2, Table 2, Selected Properties of Constantan and Hastelloy C Density Thermal Approximate Material 3 Conductivity Cost (g/cm) o (cal/cmesecs®C) ($/1b) Hastelloy C 8.94 0.03 5 Constantan 8.9 0.055 1 When the number of materials to be considered was reduced to a logical minimum, calculations were performed to determine, semiquantitatively, the physical properties that might be expected of various combinations of these materials. These calculations are described in Appendix A, and although they suggested the limiting compositions, the introduction of another variable, porosity, prohibited a direct calculation from being made of the optimum composition., This variable was considered significant for two reasons: (1) con- sistent hot-pressing to full theoretical density, especially in a piece as large as the gamma shield, is extremely difficult; (2) while voids would lower the bulk density of a hot-pressed piece, they would also lower the thermal conductivity; the relative effects were unknown and could not be predicted. Since the thermal conductivities of the materials could not be rigorously predicted, a fairly simple apparatus for the determination of thermal con- ductivity was designed and built. This apparatus is described in Appendix B. During the fabrica- tion and calibration of the apparatus several smalt (]/2-in.-dic:) composites were hot-pressed. The hot-pressing operation consisted in heat and pressure being applied simultaneously to a weighed and blended mixture of ceramic and/or metallic 2F’. Duwez and C. B. Jordan, Trans. Am. Soc. Metals 41, 194 (1949). powders, Graphite dies were used because tem- peratures greater than 800°C would be encountered. The use of an inert layer between the die wall and the material being compacted may be necessi- tated by a reaction between the charge and graphite; where there is a significant reaction, the use of a molybdenum-foil liner or coating of aluminum oxide powder will usually prove remedial. Typical hot-pressing setups and techniques employed have been described by Coobs and Bomar, 3 The results of the preliminary experiments are presented in Table 3. The data showed that the tantalum—Hastelloy C combination could not be hot-pressed to a high density; compaction was prohibited by the formation of a brittle inter- metallic compound, A similar reaction product was noted in the microstructure of the tantalum- constantan specimen, but the copper evidently retarded the reaction rate to the point that it did not interfere with compaction, Economic factors and the favorable results ob- tained with tungsten carbide—constantan and tungsten carbide—Hastelloy C indicated that these combinations warranted further consideration. The tungsten carbide—constantan composition was most easily fabricated and was therefore investi- gated first. In this system the required density of 12.0 g/ecm3 could be obtained over a composi- tion range extending from 60 wt % tungsten carbide to 100 wt % tungsten carbide simply by varying the porosity of the hot-pressed compact. The sig- nificance of porosity has been mentioned. In order for variations in porosity to be taken into account, and even for the porosity to be used toe advantage if possible, six tungsten carbide- constantan charges were pressed into I-in,-dia by 2]/2-in.-|ong slugs for thermal conductivity de- termination. Figure 3 presents the conductivities of the specimens as a function of the volume per- centages of the three phases, tungsten carbide, constantan, and porosity, present in each compact; the closed circles indicate the compositions of the compacts after they were hot-pressed. The conductivities were found to be essentially linear with temperature to 500°C, the upper limit of the apparatus. These data proved conclusively that no combination of tungsten carbide, constantan, and porosity would simultaneously fulfill the 3J. H. Coobs and E. 5. Bomar, Methods of Fabrication of Control and Safety Element Components for the Aircraft and Homogeneous Reactor Experiments, ORNL- 1463 (March 15, 1953), Table 3. Results of Preliminary Hot«Pressing Experiments . 3 Maxi COmPOSifiOI’I Dens”.y (g/cm ) axtmum R l'( - - Temperature emarks (wt %) Theoretical Attained o (- C) 60 tantalum— 12.3 12.1 1275 Compacted readily; definite Ta-Ni 40 constantan reaction; no Ni-graphite reaction 60 tantglum— 12.4 8.2 1300 Would not compact; definite Ta-Ni 40 Hastelloy C reaction; slight Ni-graphite re- action 60 tungsten carbide — 12.0 11.9 1275 Compacted readily; no WC-Ni 40 constantan reaction; no Ni-graphite reaction 60 tungsten carbide — 12,0 11.8 1300 Compacted with some difficulty; no 40 Hastelloy C WC-Ni reaction; slight Ni-graphite reaction UNCLASSIFIED ORNL-LR-DWG 15034 VALUES SHOWN ARE THERMAL CONDUC;TIVITY {cal/em-sec- C) o, ~Itns . TR IR TUNGSTEN 10 200 30 40 50 60 70 RBI CARBIDE CONSTANTAN (vol %) Fig. 3. Thermal Conductivity of Tungsten Carbide-~ Constantan, thermal conductivity and density specifications (£ < 0.10 cal/cmesec:°C, p > 12.0 g/cm?®) set by the Experimental Engineering Design Group. Investigation of the tungsten carbide—constantan system was therefore discontinued. The tungsten carbide—Hastelloy C system was then investigated in a similar manner. Four specimens were hot-pressed and their thermal con- ductivities determined. The results are presented in Fig. 4. It is evident that the conductivity is almost constant for compositions with a density of 12.0 g/cm3, probably because of the opposing effects of tungsten carbide and porosity. With the density held constant, an increase in the volume percentage of tungsten carbide produces an increase in the volume percentage of pore space. The tendency of tungsten carbide to raise the conductivity of the compact is therefore opposed by the insulating effect of pore space. UNCLASSIFIED ORNL-LR-DWG 15030 VALUES SHOWN ARE THERMAL CONDUCTIVITY ¥ }*fi, . {cal/em-sec- C) = -1y . Tt LN f’ h ; ; o S IS0 N SN . > {%fi/ ??‘\'0.0T, S < TUNGSTEN 10 20 30 40 50 60 70 CARBIDE HASTELLOY C (vol %) Fig. 4. Thermal Conductivity of Tungsten Carbide~ Hastelloy C. The composition that was tentatively chosen for use in the gamma shield was 75 wt % tungsten carbide—25 wt % Hastelloy C. The microstructure of this composition, at the specified density of 12.0 g/cm?, is shown in Fig. 5. The feasibility of hot-pressing a full-size gamma shield of this composition and density was confirmed by the successful pressing of two models of the cylinders, Because existing dies were utilized, the models were not true miniatures of the gamma shield but had charges calculated to give the same ratio of cross-sectional area to die wall area as would exist in the gamma shield. This ratio is a domi- nant consideration in hot-pressing practice. The two models were 1.20 and 2.36 in. in inside diameter, 2.23 and 3.86 in. in outside diameter, 1.25 and 174 in. high, and were pressed to densities of 11.9 and 12.4 g/cm?, respectively. - o ey Aot v !..-. " -2y ot s sAad e 4 ) e W | % UNCLASSIFIED °* | Y.22381 B3 y g | | 3 S Ve L Fig. 5. Microstructure of Tungsten Carbide —Hastelloy C. 500X, These models and smaller trial pieces were given to the Welding and Brazing Group for brozing evaluation. The tungsten carbide—Hastelloy C material was successfully copper-brazed to Inconel in a dry-hydrogen atmosphere; the copper readily wet both materials. The models were brazed to ]fiz-in.-thick Inconel plate and subjected to several thermal shocks. They were heated in an argon-filled muffle furnace at 1500°F, then air-cooled to room temperature, No cracking or thermal-shock sensitivity was noted. Figure 6 shows a small trial piece, a typical thermal conductivity specimen, and the two models after they were brazed. The only unattractive property exhibited by this material was its extremely poor machinability. All finishing operations had to be performed by grinding, pref- erably with a diamond wheel. The fabrication of two full-size gamma shields was accomplished ofter several problems had been solved in upscaling from the 3.86-in.-dia model to the 6-in,-dia gomma shield. These problems arose from the necessity of changing die materials and as a result of the difficulty of setting up the large dies in a confined space. The grade C-18 graphite which had been used as die material for the trial pieces was not available in the large (15-in,) diameter required; therefore the substan- tially weaker grade CS-312 was used for the large dies. As a result, only two runs were made be- cause the dies cracked open. A longer pressing time at a lower pressure (1500 psi as against 2500 psi) and elimination of the stress-raising sight hole used for optical pyrometer temperature measurement prevented similar difficulty in sub- sequent runs made with a new die. The second run was terminated just before the end of the pressing cycle, and even though the outside di- ameter of the piece had swelled after the die broke, the inside diameter remained true, After this was accurately as was the diameter of the mandrel cooling, inside diameter measured, UNCLASSIFIED ¥-19835 Fig. 6. Hot-PressingDevelopment Series. (a) Trial piece, (b) typical thermal conductivity specimen, (c) 2.23-in.-0D model, (d) 3.86-in.-0D model. which had formed it. A relative expansion co- efficient was then calculated which was utilized in the design of the new die. The new die produced two gamma shields which required little or no grinding of the cylindrical surfaces. The gamma shields were merely faced by grinding and the helical grooves cut with a Efi-in.-wide diamond wheel, The grooves were cut by means of an ingenious grinding technique in which a slab-mill cutter was used as a guide. The gamma shields were then copper-brazed to the heat exchanger faces of two Inconel cans. Figure 7 shows a brazed assembly before the intro- duction of the thermocouples and final sealing of the can. Thermal Shield A survey of the literature showed zirconium dioxide (zirconia) to have the lowest thermal con- ductivity of the more common ceramic materials, The thermal conductivity of zirconia is reported* 4E. H. Norton et al., The Measurement of Thermal Conductivity of Refractory Materials, NYO-3643 (March 15, 1953). UNCLASSIFIED ¥-22865 NEUTRON SHIELD THERMAL SHIELD GAMMA SHIELD Fig. 7. Fabricated Shield Plug Assembly. to be 0.004 cal/cm-sec:°C, The effect of density on thermal conductivity was not reported, nor was the effect of stabilization (addition of a small amount of calcium oxide for the stabilization of the cubic phase). Arrangements were made with Battelle Memorial Institute for them to determine the thermal con- ductivities of zirconia specimens supplied by the Oak Ridge National Laboratory. Three specimens of stabilized zirconia, one each of density 3.08, 3,52, and 4.41 g/cm®, were cold-pressed and sintered by the Ceramics Group of the Metallurgy Division at ORNL. These were machined to BMI specifications and sent there for thermal conduc- tivity determination. The thermal conductivity of these specimens is shown as a function of tem- perature and density in Fig. 8, After the thermal conductivities were determined by BMI, the Ceramics Group fabricated the thermal shields for the shield plug assembly to a density of 3.25 g/cm>; one of the shields is shown in Fig. 7. UNCLASSIFIED DRNL -LR-DWG 18704 “y S 0.0038 0.0034 .I 20 L éo)b 0.0030 o{} o o 3 ol £ & < / £ 0002 / > - = - / = 0 3 Z 0.0022 ,/ o = <{ = o I " 0.0018 / / 0.0044 / 0.0040 3.00 3.50 400 4.50 5.00 DENSITY (g/cm3) Fig. 8. Thermal Conductivity of Zirconia as a Func- tion of Temperature and Density. Neutron Shield A stainless-steel-clad copper—boron carbide neutron shielding material has been developed at ORNL for the ART.®> This material is directly applicable for use as the neutron shield in the shield plug assembly, This neutron shield is a laminated sheet con- sisting of a copper—boron carbide core clad with copper foil and stainless steel, in that order. The use of a copper matrix in the core lends a certain amount of ductility to the sheet. This core is enclosed in a copper diffusion barrier which separates the boron carbide particles on the surface of the core from the stainless steel cladding, The stainless steel, in turn, acts as a diffusion barrier between the copper and Inconel. The composite sheet is fabricated by the well- known technique; the cold-pressed and sintered core is wrapped with a copper foil and inserted in a stainless steel envelope, or billet, The billet is evacuated and sealed, then hot- and cold-rolled, The neutron shields for the shield plug assembly were cut from a 0.106-in.-thick sheet of this type of material, as manufactured by the Allegheny Ludlum Steel Corporation, The material has 6.6 wt % normal boron carbide in a 0.080-in.-thick core., The B0 content of the sheet, at 0,011 g/cm?, adequately fulfills the B'® specifications (B1% > 0.01 g/cm?) of the shield plug assembly. A microstructure of the neutron shield disk shown in Fig. 7 is given in Fig. 9. evacuated picture-frame SUMMARY The shield plug assembly protects the fuel pump motors of the ART from gamma and neutron radia- tion. |t also has limited heat transfer properties, allowing heat dissipation at full reactor power operation, yet acting as an insulator during zero- power operation to prevent solidification of the liquid fuel. The shield plug assembly consists essentially of three layers stacked in an Inconel container, Each layer, or component, has a spe- cific function; each has specific materials require- ments, After evaluation of its metallurgical and physical properties, a 75 wt % tungsten carbide—25 wt % Hastelloy C cermet was selected for use as the SH. Inouye, M. R. D'Amore, and J. H. Coobs, The Neutron Shield for the ART (to be published). Fig. 9. Microstructure of Neutron-Shield Material. gamma-shield material. The gamma-shield com- ponent was fabricated by hot-pressing a mixture of tungsten carbide and Hastelloy C powders to a density of slightly greater than 12,0 g/em>, This material fulfills the specifications of density greater than 12.0 g/cm®, thermal conductivity of less than 0.10 cal/cm:sec:°C, brazeability to Inconel, moderate thermal-shock resistance, and structural integrity to at least 1500°F, The thermal shield requires a refractory material of very low thermal conductivity., Low-density stabilized zirconia was selected for use in this component after its thermal conductivity was de- termined as a function of density and temperature, The neutron-shield specifications call for a material with o B'? content greater than 0,01 g/cm? 10 UNCLASSIFIED Y-19509 Cols 55430 T o = 0.02 Q.03 > - O 2 100 X, of the exposed foce. Stainless-steel-clad copper— boron carbide, with a B'? concentration of 0.011 a/em?, was utilized in this component of the shield plug assembly. ACKNOWLEDGMENTS The authors are indebted to o great number of Qak Ridge National Laboratory personnel for their assistance throughout this investigation and especially to the following for the work indicated: A. G, Grindell oand W. K. Stair, design; W. R. Johnson, powder metallurgy; D. H. Stafford, thermal conductivity; R. L. Homner aond J. A, Griffin, ceramics; R. L. Newbert, grinding; and G. M. Slaughter and C. E. Shubert, brazing. Appendix A DENSITY AND CONDUCTIVITY CALCULATIONS The bulk density of a heterogeneous material The densities of two-phase composites of the may be rigorously calculated by where It materials of interest are shown as a function of composition in Fig, A. 1. The thermal conductivity may be approximated by the analogy of heat flow to electric current. Limiting cases of parallel flow and series flow (assuming a purely two-phase solid) are repre- P = LV i bulk density (mass/length?), sented by Eqs. 1 and 2, respectively (see Fig. A.2 volume fraction, component i, for derivations): , : 3 _ density, component ; (mass/length”), (1 kg =k Vo +kV, UNCLASSIFIED ORNL-LR-DWG. 21985 8 PART 1 DENSITY TANTALUM o / TUNGSTEN CARBIDE a4 7 € / s > = 2 - SPECIFICATION MINIMUM wl 12 —————— — . T e el ey v v " w— e v— O 10 7 F—CONSTANTAN AND HASTELLOY C 0 20 40 60 B8O 100 HIGH = DENSITY COMPONENT (vol %5 ) MATERIAL COMPOSITION FULFILLING DENSITY SPECIFICATION Ta— CONSTANTAN >40vol Y Ta Ta—HASTELLOYC 240 vol P Ta WC —CONSTANTAN > 46 vol P, WC WC —HASTELLOY C > 46 vol T, WC Fig. A.1. Density as a Function of Composition of Two-Phase Composites. where function of composition in Fig. A.3. The calcu- lated composition ranges in which the density and ky = bulk thermal conductivity i anges _ (cal/cmesec:°C), conductivity specifications are simultaneously fulfilled are presented below: ki k, = thermal conductivities of components 1 and 2, respectively, Material c . V,,V, = volume fractions of components 1 and e cmpesthen 2, respectively. Tantalum-constantan 51 to 60 vol % Ta or 1 V] V2 66 to 74 wt % Ta (2) - = 3 . Tantalum=Hastelloy C 5% to 68 vol % Ta or kg Ry Ry 66 1o 80 wt % Ta The value resulting from the case of parallel Tungsten carbide—constantan Not fulfilled flow is the more conservative (yields highest Tungsten carbide—Hastelloy C 52 to 57 vol % WC or value of conductivity). This value is plotted as a 66 to 70 wt % WC UNCLASSIFIED ORNL-LR—DWG 21984 SERIES FLOW PARALLEL FLOW A A‘ 77_'42 "44"’W i ¢ J 1 Z PHASE f 3 - < L & - | f H HHH“HH' o Z PHASE { PHASE 2 »I \ £ PHASE 2| ||| | I ' P ! N J LI ‘ | ‘ o 1 4 A= =L / ki A R; = RESISTANCE OF COMPONENT / k; = CONDUCTIVITY OF COMPONENT / £ = LENGTH OF COMPONENT / A; = AREA OF COMPONENT / 4 Ry =Ry +FRy Fro R P o A AT M4 R kr Ar ky A, ko A, Ly T Ay £, IF Zr=1: 4=V, AND 4=V, IF Ar=1; 4= V) AND 4,=V, V; = VOLUME FRACTION, COMPONENT / V; = VOLUME FRACTION, COMPONENT / 7 V. g 1A e k= kY Ckr Tk ks Fig. A.2. Derivation of Conductivity Equations. 12 UNCLASSIFIED ORNL-LR-DWG, 21985 PART 2 0.20 TUNGSTEN CARBIDE (ESTIMATED)\‘ 0.146 THERMAL CONDUCTIVITY (ASSUMING PARALLEL HEAT FLOW) TANTALUM \l = ~ /cm-sec-°C) O N SPECIFICATION ° MAXIMUM > A SN GEEES TS el T S SR = 2 5008 2 / o Z o O - CONSTANTAN 0.04 @~ HASTELLOY C 0 0 20 40 60 8O 100 HIGH - DENSITY COMPONENT (vol %,) MATERIAL COMPOSITION FULFILLING CONDUCTIVITY SPECIFICATION Ta— CONSTANTAN < 60 vot % To Ta— HASTELLOY C < 6Bvo! Y, To WC— CONSTANTAN < 40 vol ¥, WC WC— HASTELLOY C < 52 vol T WC Fig. A.3. Conductivity as a Function of Composition of Two-Phase Composites. 13 Appendix B THERMAL CONDUCTI!VITY DETERMINATION APPARATUS A diagram of the thermal conductivity apparatus used for the evaluation of the gamma-shield ma- terials is given in Fig, B,1. This apparatus is a modification of a design presented by Kitzes and Hullings. The thermal conductivity, k£, was obtained by measurement of the temperature gradient, AI/ATS, in a specimen of cross-sectional area A and of the temperature rise, ATw, of water flowing through a Solution of the equation WeohTu Al A AT, simple heat exchanger. E = ! ]A. S. Kitzes and W. Q. Hullings, Boral, A New Thermal Neutron Shield, AECD-3625 (May, 1954). UNCLASSIFIED ORNL-LR-DWG 15084 DIMENSIONS ARE IN INCHES e T INCONEL 0.030in VERMICULITE —- ‘ | GUARD HEATER- R — HEAT SOURCE - — o = | o ™ ‘ o GUARD RING 1 | ‘ Y4-in. INCONEL - L } © o o ! - . S —7 I SPECIMEN Si T HEAT EXCHANGER — T r GUARD COOLER—— i = ' o 7L RN e pLYwooD——_——h(( { L NE 12 IF e e 3 L INSULATING |~ + THERMOPILE H _THERMOPILE BRICK COLD JUNCTION HOT JUNCTION < A ... WATER FROM - \ At L OWMETER — 1 .——WATER QUT ; Fig. B.1. Thermal Conductivity Apparatus, Where k = thermal conductivity (cal/cm-sec+°C), Wf = water flow (g/sec), €, = specific heat of water (cal/g-°C), yielded, directly, the value of thermal conductivity. The use of a multiple-point recorder allowed matching of the thermal gradients in the specimen and the guard tube. The heat inputs to the speci- men and guard heaters were individually controlled through Variac autotransformers. The temperature rise in the water was measured by a 20-junction Chromel-Alumel thermopile. The voltage developed in each of ten hot junctions was opposed by a voltage developed in a cold junction. Therefore temperature sensitivity was This ther- in conjunction with a Rubicon model 2732 portable potentiometer, gave temperature- differential readings that were reproducible to 0.01°C. The specimen was held in the heat exchanger by a neoprene O-ring. This ring also effected a water-tight seal around the specimen and allowed direct impingement of water on the end of the specimen. The water entered the heat exchanger at the center, was baffied through a circular path, and left through the side. This apparatus was found to be quite accurate. increased by an order of magnitude. mopile, Inconel, type A nickel, and Armco iron were tested and most results fell within 0.005 cal/emesec:°C of published data. The upper temperature limit was 600°C, resulting in a con- ductivity datum point at 500°C, due to the thermal gradient. It was, however, very difficult to match the specimen and guard tube in this temperature range. The upper temperature limit of dependable measurement was approximately 300°C, Attempts to measure high-conductivity materials, such as aluminum alloys, were unsuccessful be- cause a suitable gradient could not be established. 4 R 1. R. G. Affel 2. J. W, Allen 3. C. J. Barton 4. M. Bender 5. D. S. Billingten 6. F. F. Blankenship 7. E. P. Blizard 8. C. J. Borkowski 9. W. F. Boudreau 10. G. E. Boyd 11. M. A, Bredig 12. E. J. Breeding 13. W. E. Browning 14. F. R. Bruce 15. A. D. Callihan 16. D. W, Cardwell 17. C. E. Center (K-25) 18. R. A. Charpie 19. R. L. Clark 20. C. E. Clifford 21. J. H. Coobs 22. W, B, Cottrell 23. R. S. Crouse 24, F. L. Culier 25, D. R. Cuneo 26. J. H. DeVan 27. L. M. Doney 28. D. A. Douglas 29. W. K, Eister 30. L. B. Emlet (K-25) 31. D. E. Ferguson 32. A. P. Fraas 33. J. H. Frye 34, W. T. Furgerson 35. R. J. Gray 36. A. T, Gresky 37. W. R. Grimes 38. A. G. Grindell 39. E. Guth 40. C. S, Harrill 41. M. R. Hili 42, E. E. Hoffman 43. H. W. Hoffman 44. A. Holigender 45. A. S. Householder 46, J. T. Howe ORNL.-2353 C-84 — Reactors-Special Features of Aircraft Reactors INTERNAL DISTRIBUTION 47, 48. 49. 50. 51. 52. 53. 54, 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 635. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 8l. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. PME-CUAPIZTPIC-OPLPICOEICAMACDPODINCETNMEMNIIADDN--TEINOOE . H. Jordan . W. Keilholtz . P. Keim . L. Keller . T. Kelley . Kertesz . Lindaver . Livingston Lyon . MacPherson . MacPherson . Maienschein . Manly . Mann Mann . McDonald McNally . McQuilkin . Meghreblian . Milford Miller Moore Morgan . Morgan . Murphy . Murray (Y-12) . Nelson . Nessle t_r-'U‘—NSDfnf—'U<;U?UUCJ?>;UUfimO_ZU‘UJ,>. . G. Overholser . Patriarca K, Penny . M. Perry . Phillips Pigg . Reyling . Richt . Robinson . Savage . Savolainen . Schultheiss O=s==—1mxO . Scott . L. Scott . D. Shipley . Simon 15 16 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 0. Sisman J. Sites M. J. Skinner A. H. Snell C. D. Susano J. A. Swartout E. H. Taylor R. E. Thoma D. B. Trauger D. K. Trubey G. M. Watson A. M. Weinberg 105. J. C. White 106. G. D. Whitman 107. E. P. Wigner {consultant) 108. G. C. Williams 109. J. C. Wilson 110. C. E. Winters 111. W. Zobel 112-114. ORNL - Y-12 Technical Library, 115--122. 123. 124-.126. Document Reference Section Laboratory Records Department Laboratory Records, ORNL R.C. Central Research Library 127-129. 130131, 132. 133. 134. 135-137. 138. 139-140. 141. 142. 143-144. 145. 146. 147. 148-161. 162. 163-165. 166. 167. 168. 169. 170. 171-176. 177. 178. 179-180. 181. 182. 183. 184. 185. 186. 187. 188. 189. 190. EXTERNAL DISTRIBUTION Air Force Ballistic Missile Division AFPR, Boeing, Seattle AFPR, Boeing, Wichita AFPR, Curtiss-Wright, Clifton AFPR, Douglas, Long Beach AFPR, Douglas, Santa Monica AFPR, Lockheed, Burbank AFPR, Lockheed, Marietta AFPR, North American, Canoga Park AFPR, North American, Downey Air Force Special Weapons Center Air Materiel Command Air Research and Development Command (RDGN) Air Research and Development Command (RDTAPS) Air Research and Development Command (RDZPSP) Air Technical Intelligence Center ANP Project Office, Convair, Fort Worth Albuquerque Operations Office Argonne National Laboratory Armed Forces Special Weapons Project, Sandia Armed Forces Special Weapons Project, Washington Assistant Secretary of the Air Force, R&D Atomic Energy Commission, Washington Atomics International Battelle Memorial Institute Bettis Plant (WAPD) Bureau of Aeronautics Bureau of Aeronautics General Representative BAR, Aerojet-General, Azusa BAR, Convair, San Diego BAR, Glenn L. Martin, Baltimore BAR, Grumman Aircraft, Bethpage Bureau of Yards and Docks Chicago Operations Office Chicago Patent Group Curtiss-Wright Corporation 191. 192-195. 196. 197. 198. 199. 200. 201. 202. 203. 204. 205. 206. 207. 208. 209. 210. 211, 212. 213. 214, 215. 216-219. 220. 221, 222. 223. 224. 225. 226. 227. 228-229. 230--247. 248-272. 273. Engineer Research and Development Laboratories General Electric Company (ANPD) General Nuclear Engineering Corporation Hartford Area Office ldaho Operations Office Knolis Atomic Power Laboratory Lockland Area Office Los Alamos Scientific Laboratory Marquardt Aircraft Company Martin Company National Advisory Committee for Aeronautics, Cleveland National Advisory Committee for Aeronautics, Washington Naval Air Development Center Naval Air Material Center Naval Air Turbine Test Station Naval Research Laboratory New York Operations Office Nuclear Development Corporation of America Nuclear Metals, Inc. Office of Naval Research Office of the Chief of Naval Operations (OP-361) Patent Branch, Washington Pratt and Whitney Aircraft Division San Francisco Operations Office Sandia Corporation Schoo! of Aviation Medicine Sylvania-Corning Nuclear Corporation Technical Research Group USAF Headquarters USAF Project RAND U.S. Naval Radiological Defense Laboratory University of California Radiation Laboratory, Livermore Wright Air Development Center (WCOSI-3) Technical Information Service Extension, Qak Ridge Division of Research and Development, AEC, ORO 17