A detailed study of the activation of low-reactivity UO2 particles toward HF by successive oxidation and reduction was carried out. The effect of repeated successive oxidation and reduction on the reactivity of the UO2 source material toward HF was evaluated by hydrofluorination.

The following report describes the findings of air samplings taken that followed the Wasp detonation of Operation Teapot.

The following report describes the high pressure and temperature homogeneous reactor experiment which has been started at Los Alamos, as well as the hazards and safety aspects for the experiments.

This is a summarizing and reviewing report in which almost all the experimental data representing Project work done prior to 1949 on the corrosion of pure uranium are brought together and analyzed. New data obtained in this laboratory on corrosion rates in laboratory atmosphere and on the identification of corrosion products by electron diffraction are included. The data for corrosion in each of several different media have been plotted according to logarithm-of-the-rate versus reciprocal-temperature coordinates; and from these plots values for the energies and entropies of activation of the corrosion reactions have been obtained. By theoretical treatment of the role of oxygen as a negative catalyst, it is shown that this element may be expected to "poison" the corrosion rection and then act as a corrosion inhibitor. A practical significance of these data analyses is that they explain why machined uranium parts stored in inert atmospheres (helium or argon) containing only very small amounts of water vapor will corrode relatively rapidly with the formation of loose powdery oxide, whereas similar parts may be kept in dry air almost indefinitely with formation on their surface of only a discoloring, but adhered, oxide coating.

Multivariate statistical analysis to support the National Uranium Resource Evaluation and to evaluate strategic and other commercially important mineral resources

The angular distribution of fission fragments from the neutron-induced fission of several isotopes has been studied. Distributions were observed for thermal neutrons on U233 and U235, Lady Godiva leakage neutrons on U235 and U238, and 14 Mev neutrons on U233, U235, U238, Th232, and Np237. No anisotropy was observed for thermal neutron fission, whereas for Lady Godiva neutrons and 14 Mev neutrons the probability of fission along the axis of the neutron beam was determined to be higher than for fission in the orthogonal direction. Experimental results are given on pages 10 and ll.

Magnesium oxide reduction crucibles have been developed that increase the processing efficiency of uranium and plutonium production. The characteristics of the crucibles are described.

By means of measurements with a double ionization chamber, the average fission cross section of U238 for neutrons from the fission of U235 was determined in terms of v, the average number of neutrons per fission of U235. the number of fission of U238 was measured in one of the ionization chambers while the number of fissions from the fission neutron source of U235 was measured in the other chamber. In the nine runs made to determine the cross section, a variety of different methods was used to determine the number of fissions and the mass of U238.

A device has been designed which will support small spheres and cylinders in a vacuum system during a plating operation. While supporting the object to be plated, the device automatically shifts the position of the supports so that the coating is evenly distributed. This report describes the mechanism by which this motion is achieved.

The bibliography provided investigates the following sources: Chemical Abstracts 1947-1950., Metallurgical Abstracts Vols. 1-18., ASM Review of Metals Literature Vols. 1-6., J. Institute of Metals Vols. 78-80 (No. 7)., Physics Abstracts 1937-1950.

Thermal neutron measurements made on five weapons during Operation Teapot indicated that these neutrons contribute at most 2 per cent of the total neutron dose in air. However, the total fluxes were high and thermal neutrons may become important under shielding conditions and may significantly affect the responses of the film badges and certain sensitive dose detectors, especially when the neutron to gamma flux ratio is high.

This technical report is a sequel to LA-596, "Efficiency for Very Slow Assembly" by K. Fuchs. Herein are given estimates of temperature rise and pressure developed as a result of active material slowly being driven supercritical. Marginal assembly rates can thus be determined for both metal and solution assemblies above which the disassembly by thermal expansion is explosive in the sense that the active material or containing vessel is ruptured.

This technical report describes a plant-scale procedure for concentrating plutonium and americium in slag and crucible (metal reduction residues) and other recovery solutions by a calcium oxalate carrier precipitation Conclusions from exploratory laboratory tests on the variables affecting the efficiency are included.

From abstract: "Detailed calculations were undertaken in an attempt to explain some post-shot observations of the underground Bernalillo shot. A procedure was developed to calculate with a one-space dimensional code both the flow of energy up and down the hole and the energy loss into the walls of the hole."

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.

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.

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 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.

From abstract: "The deposit on the rods is in the form of a brittle uneven tube which is cracked off and subsequently pulverized to a 200-mesh powder. This report is chiefly concerned with methods of consolidating this powder and shaping it into forms required, though it also discusses to some extent other methods of shaping boron or born-rich materials."

The corrosion of uranium in moist air is more rapid than had been thought previously. Earlier recommendations were based on test of 300 hr duration. In tests which were conducted for over 1000 hr, moisture has less effect than in those tests made over shorter periods. The corrosion of uranium by dry and moist air has been studied at 38, 57, and 75 degrees C. Although moisture increases the rate of initial attack, after 200 to 500 hr the effect is reduced and an accelerating corrosion rate overshadows the initial effects of moisture.

A uranium metal critical assembly consisted of a 15 inch diameter core with an average U235 content of 16-1/4%, surrounded by a 3 inch thick natural uranium reflector. The critical mass was 692 kg of core material.

Data on critical configurations of fissionable metals are summarized in a form emphasizing the influence of conditions commonly of concern in nuclear safety questions.

Critical mass measurements on graphite-tamped, heterogeneous oralloy-graphite systems have been made as a safety guide for certain oralloy casting procedures. Various concentrations were obtained by alternately stacking 10.5 in. diameter oralloy and graphite plates. In the relation Oralloy critical mass = constant x (fraction of oralloy in the core volume) -n values for the exponent, n, in the neighborhood of 0.70 were obtained.

Certain oralloy (Oy) lattices were immersed in infinite water for determining critical masses at various low-Oy densities. Three Oy unit sizes were used. In a broad sense the experiment shows safe and unsafe conditions for handling heterogeneous Oy-water mixtures.