Chemical and engineering data were obtained for the feed digestion system and the extraction-scrub step of the Monex tributyl phosphate solvent-extraction process for recovering thorium and uranium from nitric acid-digested unclarified monasite sludge. Tests of the recommended conditions in a 2-in.-dia pulsed column demonstrated that thorium losses were approximately 1.2% and uranium losses, 1.5%. The flowsheet is workable but is not necessarily optimum.

New systems involving the exchange of boron between boron trifluoride and boron trifluoride addition compounds have been explored. These systems have large separation factors and potentially simple reflux mechanisms. A precise determination of this separation factor for the anisole-boron trifluoride system gave the value (see report). Boron exchange was found to occur between BF and BCl3. Several homogenous catalysts have been found which activate the hydrogen-water exchange, but none are adoptable to the production of deuterium because of the slow exchange rate. Platinum or platinum oxide may be usable as a heterogeneous catalyst with proper support or dispersion techniques. The high-pressure solubility of hydrogen in several amalgams was investigated in connection with a unique countercurrent exchange system. A proposed system involving isotopic exchange between lithium dipivaloylmethane in diethyl ether and lithium hydroxide in aqueous solution was shown to give little or no isotopic separation. Column studies of the carbonate system exchange reaction were concluded with a 40°C run. Slightly higher enrichment of N15 was obtained than at 30°C . The temperature dependence of all in this system was measured between 15 and 45°C. The factor increases with temperature, showing a tendency toward a maximum near 45°C. Isotopic exchange appears to …

In scouting tests, a number of metals used in nuclear reactor fuel elements were dissolved by 44.5-48.5-7.0 mole % ZrF4-KF-NaF fused salt at 675°C through which HF was being passed. These included type 304 stainless steel at 4 mils/hr; type 347Nb stainless steel at 7 mils/hr; thorium at 14 mils/hr; nonirradiated uranium at 17 mils/hr; zirconium at 22-35 mils/hr; titanium at 31 mils/hr; and Zircaloy-2 at 22-46 mils/hr. Only small amounts of volatile fission products formed when irradiated uranium was dissolved. Variables that appear to affect the dissolution rate are the composition of the fused fluoride, the fused fluoride temperature, the HF flow rate, the metallurgical characteristics of the material being dissolved, and the presence of other metals. The low dissolution rate of 0.001 mil/hr observed for nickel suggests that it may be suitable as a material of construction for reaction vessels.

The development of ionic methods for the determination of corrosion products in the highly radioactive Homogeneous Reactor (HR) fuels has been of major interest in the work of the Ionic Analyses Laboratory. Methods for the spectrophotometric determination of aluminum and for the polarographic determination of iron in HR fuels have been developed. The polarographic determination of molybdenum in uranyl sulfate solutions was studied. A polarographic method for the determination of zinc was developed. A fluorometric method for the determination of microgram amounts of fluoride was studied. Three organic reagents were investigated as precipitants for microgram quantities of zirconium in HR fuel. The automatic photometric titration technique was applied to the determination of thorium and of sulfate. A method was developed for the ionexchange separation and potentiometric titration of cobalt. The ultraviolet absorption spectra of technetium and rhenium were studied.

The ORNL 86-in. cyclotron is being modified to provide for deflection of the proton beam. It is expected that operation will be resumed late in the spring. Nuclear physics work was limited, for the most part, to interpretation of previously collected data and to making preparations for utilizing the deflected beam. It was found that for certain isotopes the production rates could be almost doubled by operating at a slightly reduced energy and a much larger current. With the use of the ORNL 63-in. cyclotron, the absolute values of the electron capture and loss cross sections for 26-Mev nitrogen ions were obtained. The angular distribution of the cross sections for elastic scattering of nitrogen by nitrogen was measured at energies from 13 to 22 Mev. A double-focusing 90-deg magnet is being planned for use in identifying stable reaction products from nitrogen-induced reactions. The major components of the revised 44-in. test cyclotron were assembled and are being tested. Consideration is being given to the use of these components, along with a new 20,000-oersted magnet and a shielded cyclotron room, and if the tests are satisfactory the Laboratory will have available a machine which will accelerate N5+ ions to 81 Mev.

A preliminary chemical flowsheet is presented of a fluoride volatility process for recovering and decontaminating uranium from heterogeneous reactor fuels after dissolution in a fused salt. In laboratory work, a gross β decontamination factor of > 10 4 was obtained in the fluorination of a UF4-NaF-ZrF4 melt by passing the product UF6 through NaF at 650°C. The solubility of UF6 in molten NaF-ZrF4 was shown in kinetic studies to cause a lag in the evolution of UF6 from the fluorinator. Corrosion of nickel in the fluorination step appeared to be 2-4 mils/hr during the time that uranium was present. The average corrosion rate over the process as a whole was less than O.4 mil/hr. Earlier studies were reported in ORNL-1709 and 1877.

A satisfactory ion-exchange-polarographic method was developed for the determination of either chromium(VI) or total chromium in Homogeneous Reactor fuels. Total chromium is determined as chromium (VI) , i.e., chromate, and in the same way as is chromium(VI), after chromium in the lower valence states is oxidized to chromate by potassium permanganate. Chromate is separated from all interfering metal ions in the fuel by ion exchange on a Dowex 50 resin column. The Chromate in the effluent is determined polarographically in approximately 0.75 M sodium hydroxide solution as supporting electrolyte. A well polarographic wave is obtained for the chromium (VI) chromium (III) reduction at a half-wave potential of -0.85 volt vs. the S.C.E. The relative standard deviation of the data for 2 μg of chromium (VI) per ml was 2%; for 4 μg of total chromium per ml, it was 3%. An ion-exchange-polarographic method was developed also for the determination of chromium(III). Chromium (III) is separated from all interfering ions in the fuel by ion exchange on a Dowex 1 resin column. The chromium (III) in the effluent is determined polarographically in a 1M ammonia-1M ammonium chloride supporting electrolyte. The wave obtained at a half-wave potential of -1.42 volt vs. the …

A theoretical and experimental investigation of the coefficient for diffusion of ions across a magnetic field Is described. The resultant diffusion coefficient is found to vary inversely as the square of the magnetic field strength, in accord with the usual collison-diffusion theory. The magnitude of the coefficient is much larger (x700) than the coefficient predicted by the usual ambipolar diffusion theory. This discrepancy is resolved by showing that diffusion across a magnetic field is not ambipolar in character in most arc experiments. The final experimental and theoretical values are in good agreement, and it is unecessary to postulate any additional diffusion mechanisms, such as plasma oscillations.

Part I. Experimental Reactors: The effect of prompt-neutron lifetime upon reactor safety was investigated for the HRT. It was found that for a given pressure rise the allowable rate of reactivity addition was relatively insensitive to the average prompt-neutron lifetime, although the rate de creased somewhat with decreasing lifetime for the higher pressure rises. With only source neutrons present and the reactor initially subcritical, the allowable rate was practically independent of the initial value of k£. For a core-pressure rise of 400 psi, the corresponding rate of reactivity addition was about 0.8% per second; for a pressure rise of 4000 psi, the rate was 2.5 to 3.0% per second. Part II. Thorium Breeder Reactor: An economic study of one-region thorium breeder reactors was completed. Where possible, the process characteristics and cost factors were the same as those used previously in studies of two-region-type reactors. The mini mum-cost reactor is about 12 ft in diameter, operating with 260 g of thorium per liter on a chemical processing cycle of about 450 days. The ratio of U232 to U233 produced is approximately 2 x 10~4 VIM in the minimum-cost one-region system, compared with 4 x 10 5 in the two-region system. The …

The development of the reactor layout is continuing. New features that have been incorporated because of stress, fluid flow, or fabricability considerations include an elliptical fuel expansion tank, a rounded dome to enclose the top of the reactor, a newly designed sodium pump impeller, and other related items. Recently completed heat exchanger tests yielded consistent data from which a series of heat exchangers is being designed. The most promising of these will be chosen for the ART.

Bench scale studies have been made of the recovery of uranium from acid leach liquors (and slurries) by solvent extracting with di (2-ethylhexyl) phosphoric acid in an organic diluent. Uranium may be stripped from the organic solvent by either alkaline or acidic reagents, the former having been studied in greater detail. On the basis of these tests, a recovery process may be considered which shows promise both from the standpoint of operation and chemical costs. Under proper conditions, vanadium can also be extracted by the di (2-ethylhexyl) phosphoric acid and stripping again may be accomplished with either acidic or alkaline reagents. Preliminary studies have been made of these possibilities. In addition to di (2-ethylhexyl) phosphoric acid, some other organophosphorus acids, have been cursorily examined in respect to their extraction and/or stripping performance.

A summary of the laboratory development program on aqueous uranium slurry fuels for the Homogenous Reactor Project during the period April 1951 through March 1953 is presented. These investigations were devoted primarily to a study of the uranium oxides in aqueous suspensions. It was concluded that U(VI) was most likely to be the stable valence state in such slurry fuels and it was shown that β-UO3·H2O platelet crystals were the stable modification at 250°C. Very pure slurries of β-UO3·H2O platelets, uranium concentration of 250g/liter and average particle size of about 10 μ, had favorable settling rates and could be easily redispersed. Their viscosity and corrosion rate in stainless steel were comparable with those in water. Exposure of these slurries to pile radiation disclosed that radiolytic hydrogen and oxygen gas pressure comparable in magnitude to those of uncatalyzed uranyl sulfate solutions could be expected. Fission products in the irradiated slurries were predominantly associated with the solids. Radiation also tended to promote caking of these solids on the walls of the radiation bombs. Uranyl phosphate and the magnesium uranates were briefly investigated as alternate system but were not found satisfactory. The program was discontinued before the feasibility of uranium slurries for reactor …

An investigation of the materials for use in the water-moderated and cooled Aray Package Power Reactor (APPR) operating at about 500°F was made. The available literature was analyzed, and the results of the different investigators were compared and averaged. Twenty different materials, including stainless steels, nickel alloys, Stellites and others, were investigated from the point of view of physical properties, susceptibility to radiation damage, and corrosion resistance. Corrosion rates were established for all the materials under various conditions, such as irradiation, flow weld, stress, and various water conditions. Type-304 stainless steel was selected as the basic structural material. Operating conditions, to maintain minimum corrosion, were established also.

An investigation of the materials for use in the water-moderated and cooled Aray Package Power Reactor (APPR) operating at about 500°F was made. The available literature was analyzed, and the results of the different investigators were compared and averaged. Twenty different materials, including stainless steels, nickel alloys, Stellites and others, were investigated from the point of view of physical properties, susceptibility to radiation damage, and corrosion resistance. Corrosion rates were established for all the materials under various conditions, such as irradiation, flow, weld, stress, and various water conditions. Type-304 stainless steel was selected as the basic structural material. Operating conditions, to maintain minimum corrosion, were established also.

The indicated methods for determining the following constituents of Diban, which is an aqueous solution of dibasic aluminum nitrate, Al(OH)2NO3, were evaluated statistically: 1aluminum by gravimetric, volumetric, and spectrophotometric procedures, 2. basicity (hydroxyl value) by formation of an aluminum complex and titration of the free acid with standard alkali solution, 3. total nitrogen by the Kjeldahl method, 4. ammonia by the Kjeldahl method, and 5. nitrates by means of a cation-exchange resin and titration of the liberated acid with standard alkali solution. Recommendations are made regarding the preferred methods of determining the constituents in dibasic aluminum nitrate and regarding means of minimizing errors in these analyses.

The fabrication of heat exchangers and radiators to be used in conjunction with high-temperature nuclear reactors may present exceedingly complex problems. Rigid heat transfer requirements may necessitate the use of compact assemblies of thin-walled small-diameter tubes as integral parts of the heat transfer units. Intricate designs may also be required in which cooling fins must be securely joined to the tubes at closely spaced intervals. In addition to the difficulties in fabrication imposed by the designs themselves, the high operating temperatures involved require the careful selection of materials and joining techniques. The choice of fabrication procedure for a given component must not only be based upon the stresses and temperatures to be encountered, but also upon special factors peculiar to nuclear service. Since many reactor applications employ highly corrosive environments, compatibility of the structural ma terials with the corrosive media is of paramount importance. The low nuclear cross-section require ment for brazing alloys to be used inside the re actor also places stringent limitations on the possible choices of in-pile applications. The use of boron in alloys for certain service may not be considered feasible, for example, because of its high nuclear absorption cross section. Although welding is used extensively …

Several plates of 98.7% Th - 1.2% U 235 (clad in aluminum) were irradiated in the MTR for an integrated flux of 2.6 x 10 21 neutrons/cm2. Although these samples represent an early development in bonding of aluminum to thorium and there are better methods at present, the bond proved to be quite strong and both clad and core were dimensionally stable under irradiation. The production of uranium 233 was as much as theory would indicate and the total amount of fissionable material material after irradiation and after decay of the protactinium 233 was greater than before irradiation. A fuel element of this nature appears to offer excellent potentialities from the standpoint of radiation stability.

Continued work on the adsorbability of metal complexes from concentrated LiCl solutions and LiCl-HCl mixtures on a strong-base anion-exchange resin further demonstrated the much higher adsorbability of these complexes from LiCl solutions than from HCl solutions. The effect is believed to be due to the formation of less strongly adsorbed undissociated chloro-complex acids in the case of the HCl solutions.

This report presents data obtained from processing 33 Clementine Reactor fuel elements in the ORNL Metal Recovery Plant to recover approximately 15 kg of plutonium and 0.16 g of americium.

Construction of the HRT reactor shield tank was completed, and the inside surfaces were painted. The roof structure for the tank is being assembled in preparation for an acceptance pressure test. Service piping and instrument lines are being installed in the central room area by ORNL craft forces. This work is approximately 50% complete. Fabrication of all temperature system components, except the blanket outer storage tanks, has been completed.

LITR Fluoride-Fuel Loop. — The inconel loop was dismantled for removal of the samples and for recovery of the uranium by using the remote cutting tools installed in a half cell of the Solid State Building. Disassembly proceeded without incident. An electric-arc cutting technique was developed for removal of the stainless steel enclosure around the pump bowl. Fission power and maximum flux were determined by irradiating a simulated loop, by heat-balance calculations, by radiochemical analyses for fission products in the fuel, by measuring the activation of cobalt foils attached to the loop, and by activation of the loop tubing itself. The determination of the power by these various methods gave 2.5 to 2.8 kw during operation of the loop, and the maximum power density was 0.4 kw/cc. Chemical analyses of the fuel were carried out to determine U, Zr, and the major constituents of inconel: Ni, Cr, and Fe.

Progress report of the Oak Ridge National Laboratory Biology Division providing updates on various projects, experiments, and other work. This report includes a summary of scholarly output from the division and departmental activities in: cytology and genetics, microbial protection and recovery, mammalian recovery, mammalian genetics and development, pathology and physiology, microbiology, biochemistry, enzymology and photosynthesis, plant biochemistry, general physiology, and biophysics.

An ion-exchange -- polarographic method was developed for the determination of iron(III) in Homogeneous Reactor Fuels. Copper, which interferes, is removed from the fuel by plating it onto a cadmium coil. Iron is oxidized to iron(III) by potassium permanganate, and the iron(III) is separated from interfering metal ions by ion exchange on a Dowex 1 resin column that is in the sulfate form. The iron(III) in the effluent is determined polarographically in 0.5 M sodium citrate solution as supporting electrolyte. A fairly well defined polarographic wave is obtained for the iron(III) → iron(II) reduction at a half-wave potential of approximately -0.15 v. vs. the S.C.E. The relative standard deviation of the data for 2 µg of iron(III) per ml of solution in the polarographic cell was 6.5%; for 10 µg of iron(III) per ml it was 0.6%.

Two 500-kw fused-fluoride-to-Nak heat exchangers, two 500-kw NaK-to-air radiators, and a 20-tube high-velocity heat exchanger were fabricated for a heat-exchanger development program. A construction procedure, utilizing both inert-arc-welding and high temperature dry-hydrogen brazing, was used successfully on all of the units. The tube-to-header joints were welded and back-brazed; the manifold joints were inert-arc-welded with full penetration; and the tube-to-fin joints were brazed. A detailed description of the fabrication of each type of component is discussed and a cost analysis of the 500-kw units is presented.