Abstract: A method for separating small amounts of scandium (1 to 10 mg.) from a gram of uranium depends upon formation of insoluble uranium peroxide while the scandium in solution is complexed with ethylenediamine-tetraacetic acid. The precipitated peroxide carries down less than 30 p.p.m. of scandium. Uranium left in solution, less than one milligram in amount, does not interfere when the scandium is precipitated as ammonium scandium tartrate and determined gravimetrically by ignition of the tartrate to the oxide.

The increased use of tritium monitoring devices has made it necessary to devise a scheme for the calibration of such instruments. Several methods for setting up known concentrations of tritium were considered. A dynamic system containing tritium as HTO vapor or gaseous HT was selected because of the ease of control of variables. The variables that have been considered are: ,1. The effect of rate of air flow through the instruments. 2. The effect of humidity on instrument response. 3. The effect of ion collection ahead of the ion chamber. 4. The variation of “hold time” from the generation of tritium to its passage through the ion chamber. 5. The instrument response to several concentrations of tritium as HTO vapor and gaseous HT. The following three types of monitoring devices have been calibrated:1. Model 101 Sniffer of Group P-1. 2. Cl-1 Vibrating Reed Electrometer of Group CMR-7. 3. Modified TIB of Group H-6.

This report brings together an extensive accumulation of material replacement (danger coefficient) data for the various oralloy critical assemblies at Pajarito. Corresponding values of effective absorption and transport cross sections are derived. In certain favorable cases, inelastic scattering contributions to the effective absorption cross sections are estimated. Special applications of material replacement data include computation of the relationship between oralloy critical mass and concentration of a diluent and hydrogen isotopic analysis of heavy water and heavy polythene.

The development of sampling methods and some field results of the off- site air sampling stations at the Nevada Proving Ground are reviewed. A technique of radioautography is presented which yields information about the activities of individual fall-out particles. This technique gives a comparison of particle activities from air drops and tower shots and a reason for the greater contamination associated with the latter. It also indicates that air samplers do not capture the most active fall-out particles, presumably because of their large size.

The quantitative estimation of submicrogram amounts of boron in zirconium hydride using a colorimetric procedure is described. Solution of the sample in sulfuric acid or hydrofluoric acid and subsequent distillation of methyl borate without boron loss or contamination is shown to be possible. Using the curcumin color reaction, quantities of boron as low as 0.01 microgram can be detected. The method should apply equally well to zirconium metal and compounds, providing they can be dissolved under conditions that do not result in loss of boron and if the resulting solution will permit the quantitative removal of boron by distillation as methyl borate.

The fluorometric method for determining microgram quantities of uranium dissolved in concentrated sulfuric acid was reinvestigated for the purpose of measuring any interference caused by plutonium in uranium samples. No plutonium fluorescence, and therefore no positive errors due to plutonium, were observed. Limited transmittance of hexavalent plutonium in sulfuric acid at 513, and especially at 360 millimicrons, produces variable negative errors in uranium determinations.

The initial growth of irregularities on an interface between two compressible fluids is studied for impulsive (i.e., shock) acceleration. It was found that the ultimate rate of growth is roughly the same as that given by the incompressible theory, if the initial compression of the irregularities and of the fluids is taken into account.

From abstract: "An apparatus is described which automatically separates a flow of drops into a series of equal samples."

A method of numerical solution is developed for calculating the Lapre coolant pressure drop and power output with variable coolant inlet pressure, flow rate, and reactor solution temperature. The results of a series of calculations are presented that show excessive pressure drops and sonic exit flow as the flow rate is increased and the inlet pressure is decreased. Both supercritical and subcritical coolant flow regions are investigated. Reactor power is shown to be strongly dependent on the solution temperature in the region of 70O-75O degree F. At the design flow of 12 gal/min, excessive coolant pressure drops are encountered at inlet pressures of 2000 lb/in. and below.

Four uranium alloys containing nominally 0.5, 1.0, 1.5, and 2.0 w/o molybdenum were investigated with respect to their response to hardening by heat treatment. The several alloys were heated at elevated temperatures to secure solid solution, then quenched and reheated at lower temperatures to obtain hardening. The procedure followed the well known industrial practice of solution treatment and precipitation hardening. The results showed that all the alloys could be hardened by a suitable heat treatment. No specific temperatures are recommended; however, within the limits of the investigations, a solution treatment at 850 degree C followed by a water quench and reheat at 450 degree C gave a considerable increase in hardness. The time at temperature to secure maximum hardness would need to be determined as a function of mass and section shape. It is presumed that other mechanical properties of the alloys would be influence by heat treatment in a similar manner corresponding tot he effect upon hardness.

Am III and Pu III have been recovered on a plant scale by extraction with tributyl phosphate from slag and crucible and other recovery solutions. Process losses were 0.03% Am and 0.01% Pu. The product stream contained 0.08 gram Am per liter and 0.15 gram Pu per liter. The final solution cleanup to allow discard (total alpha activity equivalent to less than 10(-4) gram Pu per liter) was accomplished by tributyl phosphate extraction of Pu III under conditions of low acidity and high nitrate.

The opacity and thermodynamic properties of air at temperatures above 10 e.v. and densities below normal have been calculated under the guidance of H. Mayer in accordance with the prescription given in AECD 1870 (LA-647). Corresponding to given densities and temperatures, self-consistent distributions of electrons in bound states and their eigen energies are determined. With this information we compute the thermodynamic properties of air and the frequency-dependent absorption coefficients. Finally the opacity--a weighted average of the latter--is found

The following report presents a discussion of the method for hydrodynamic problems, together with some new considerations that have arisen concerning the method.

A spectrophotometric method used in the determination of thorium was modified for the purpose of analyzing plutonium alloys which contained 0.01 to 0.8 percent thorium. Absorbance values were measured at 545 millimicrons for solutions containing thorium and thorin, the organic reagent added to form a colored complex with thorium in the presence of plutonium (III) . With plutonium-thorium 0.8 percent thorium, the average recovery of thorium was 99.6 +- 1.5 percent. For similar samples containing 0.01 to 0.2 percent thorium, the average recovery 101.0 +- 3.4 percent, after the thorium was separated from plutonium by precipitation of thorium fluoride with the aid of lanthanum fluoride as a carrier.

The index of refraction of PuO2 made by thermal decomposition of PU(C2O2, 6H2O gradually increases from a value < 1.9 to 2.40 as the decomposition temperature is increased from 150 degree to l000 degree C. This change in refractive index parallels a gradual change in the x-ray diffraction pattern from weak, diffuse lines for PuO2 ignited at 150° to sharp, well resolved lines for PuO2 ignited at 1000°C. Similar results are observed for PuO2 made by thermal decomposition of Pu2(C2O4)3*11H2O. The refractive index of PuO2 made from Pu metal at 170°C is 2.40 and is not affected by further ignition at higher temperatures, although crystal growth does occur. The rate of solution of PuO2 in an HCl-KI solution is greatest for samples prepared at low temperatures and decreases markedly for oxides ignited at higher temperatures. These observations hive been interpreted to mean that ignition at higher temperatures causes a gradual perfection of the originally highly distorted and impurity-containing PuO2 lattice obtained by low temperature decomposition of the oxalates and promotes the slow growth of crystallites. Both factors decrease the reactivity of the PuO2.

With the assumption of infinite conductivity a simple model may be constructed for the dynamic construction of a current carrying plasma, i.e., the pinch effect. The magneto-hydrodynamic equations of this model are discussed and solved. It is also shown that the infinite conductivity model can be derived from a picture of particles orbiting without collisions in the fields set up by their motions.

The conductivity of ionized gases is treated by a method similar to that used by Alfven in his book "Cosmical Electrodynamics". The results differ from those of Alfven. In particular, it is shown that Alfven's conclusion, that whenever the Hall current disappears the conductivity becomes independent of the magnetic field, is not true in general. Moreover, it is not true under just the conditions of interest for the "Pinch Effect". The main conclusions of the present paper are (1) of currents down a tube, the ion component is the small fraction of m/M of the electron current, regardless of the magnitude of the magnetic field; (2) the conduction along the tube depends on the transverse motion of neutral mass, i.e. on the radial velocity of u(r) of the gas in the tube.

The effects of certain process variables on the production of uranium tetrafluoride from U3O8 on the 250 g. (uranium) scale, and smaller scales in a few cases, have been studied. It was found that the initial step (reduction of U3O8 to UO2 by hydrogen) is essentially complete in 15 minutes at 700 degree C. The rate of conversion was shown to be temperature dependent, the greatest increase in rate of conversion occurring in the vicinity of 500 degree C. In the conversion of UO2 to UF4 by hydrogen fluoride, the optimum temperature was found to be abut 600 degree C. For a reaction time of 5-1/2 hours, both higher and lower temperatures yielded less completely converted products. An increase in rate of conversion, both in reduction and hydro-fluorination, resulted when smaller quantities of material were used. Changes resulting from the present study and yielding an increased efficiency in the production process are described.

The index of refraction of PuO2 made by thermal decomposition of PU(C2O2, 6H2O gradually increases from a value < 1.9 to 2.40 as the decomposition temperature is increased from 150 degree to l000 degree C. This change in refractive index parallels a gradual change in the x-ray diffraction pattern from weak, diffuse lines for PuO2 ignited at 150° to sharp, well resolved lines for PuO2 ignited at 1000°C. Similar results are observed for PuO2 made by thermal decomposition of Pu2(C2O4)3*11H2O. The refractive index of PuO2 made from Pu metal at 170°C is 2.40 and is not affected by further ignition at higher temperatures, although crystal growth does occur. The rate of solution of PuO2 in an HCl-KI solution is greatest for samples prepared at low temperatures and decreases markedly for oxides ignited at higher temperatures. These observations hive been interpreted to mean that ignition at higher temperatures causes a gradual perfection of the originally highly distorted and impurity-containing PuO2 lattice obtained by low temperature decomposition of the oxalates and promotes the slow growth of crystallites. Both factors decrease the reactivity of the PuO2.

A method is developed for using the relatively easily measured fission parameters, together with the mass equation of fission and the evaporation model of the nucleus, to determine the emission probabilities of the fission neutrons. The distribution of the kinetic energies of the fragment pairs enters into these calculations in a sensitive manner. Neutron emission probabilities are computed for the fission of the compound nuclei U/sup 234/ U/sup 236/, and Pu/sup 240/, for which cases reasonably adequate data on the fragment pair energies are available. Although the corresponding data for the fission of the compound nuclei Th/sup 233/, U/sup 238/, and U/sup 239/ are considerably poorer, neutron emission probabilities are also computed. The calculated results from this method are in good agreement with direct measurements of fission neutrons.

Specific surface and bulk density measurements were made on samples of 22 U308 materials which had been prepared by calcination at 900°C of widely differing uranium peroxide precipitates and had been evaluated as to "reactivity" by successive treatment with hydrogen and a mixture of anhydrous hydrogen fluoride and hydrogen in a production-type batch process for the preparation of UF4. Specific surface and bulk density measurements were also made on samples of the 22 corresponding U02 intermediates. The ranges of values encountered in the U308 samples and in the U02 samples were 0.05 m /g to 0.37 m /g and 0.03 m /g to 0.33 m /g, respectively, for specific surface and 3.7 g/cm to 1.8 g/cm and 4.9 g/cm to 2.7 g/cm3, respectively, for packed bulk density. Specific surface varied inversely with packed bulk density for U308, the data showing a good correlation. A very poor correlation between specific surface and packed bulk density of U02 was obtained. The conversion of U308 to UF4 n the standard process varied from 22% for the lowest specific surface, highest bulk density oxide to 98 to 99% for the high specific surface, low bulk density oxides. The observed values for properties of the …

Part 1. The neutron fission cross section of U237 has been measured in a thermal neutron spectrum and in a somewhat degraded fission spectrum. The fission cross section for thermal neutrons is found to be <2 barns; the ratio of the fission cross section of U237 to that of U235 in the degraded fission spectrum is found to be 0.476 +- 15% which corresponds to [formula] in this spectrum equal to 0.66 +- 0.10 barns. Part 2. The average neutron fission cross section of U237 has been measured in a neutron energy range extending from approximately 100 ev to fission spectrum. the average fission cross section in this spectrum is found to be 0.70 +- 0.07 barns. Part 3. The low thermal fission cross section for U237 (<2 barns) indicated that the excitation function for fission probably shows an effective threshold. If the excitation function is like all other heavy element (Z > 90) neutron fission excitation functions, it will exhibit a region of approximate constancy starting at a neutron energy of 0.5 to 1 Mev above its effective threshold and extending to a neutron energy in the neighborhood of 5.5 Mev. A hypothetical excitation function for neutron fission of …

The extraction of americium nitrate with tributyl phosphate has been investigated for aqueous solutions containing sodium nitrate and nitric acid. Americium nitrate is found in the organic phase as free molecules or ions and as the complex (Am(NO3)3. Aqueous solutions containing nitric acid introduce a competitive factor through the formation of the TBP-KNO3 complex in the solvent layer. In addition. americium nitrate is complexed in the aqueous phase by nitric acid.

A class of critical assemblies has been considered in which the core consists of an oralloy bearing gas at more or less standard pressure and temperature and the reflector is an efficient moderator with a small thermal capture cross section. Age and diffusion theory have been applied to compute the probability that a fast neutron is thermalized by the reflector and them captured by the core. It is first assumed that fast or epithermal neutrons do not interact wit the core and it is later shown that this assumption should be a good one for many cases. The reflector may be a thick spherical shell. It is shown that oralloy masses of a few kilograms can be critical within thick reflectors of D2O, Be, C or combinations thereof. Curves are attached which enable one to estimate critical configurations.