The following report calculates how many neutrons are produced by the O-16([alpha]-n) reaction in a thin and uniform polonium oxide layer.

Abstract. A review of all work on uranium hydride published in the CC, CT, CN and CE reports to January 1, 1944, is presented. Some additional information not yet published has been included, so this report includes all data known from the above sources and at Ames to the above date. This report supersedes all previous report on uranium hydride coming out of the Ames laboratory.

Technical report describing a gasometrical method for the determination of H2 in extruded U rods.

Technical Report: A generalized review of the chemical problems and researches related principally to the heavy water homogeneous pile is presented herewith. The report covers researches performed principally by the Columbia Group who initiated the study. This report contains a chronological outline of the development, a discussion of some special topics whose significance is paramount in any slurry pile discussion, and finally an outline of important research problems remaining, roughly graded in order of their importance. No attempt has been made to be either complete or detailed in the discussion. The emphasis has been principally on furnishing a broad guide to those who may t some future date take up this work.

Technical report. Areas covered are properties of uranium halides, properties of uranium nitrides, and hydride formation at high pressure.

Technical report describing the investigation of the short-lived activities produced in oxygen compounds by irradiation with pile neutrons. The most prominent of these activities in cooling water is a beta and gamma emitting activity of about 8 second half-life. Because of its production by epicadmium neutrons it was believed to be the 8 second N16 produced in the pile by n,p on O16. The identification has been accomplished and it is established that the 8 second activity is N16. Part 2 of the report deals with the determination of the recoil range of the Al28 atoms formed by pile n,p reaction on Al27.

Technical report. Long-time tests have been made on the effect of various types of radiation on the corrosion of 2S aluminum in simulated W water. In no case was any acceleration of corrosion by the radiation observed; the effect of radiation, if any, appeared to be a protective one. Deuteron irradiation did accelerate the corrosion of mild steel at low flow rates in hot water of pH 6 to 7, but no appreciable effect was observed with copper, stainless steel, or tuballoy. The general theory of the effect of radiation on corrosion is discussed, with the conclusion that no acceleration of corrosion by radiation is to be expected in most cases of practical interest.

Technical report. The extent of the Wigner effect in graphite at any point in a pile is sensitive to the local structural situation. It is greater near a slug. These control experiments give information on changes in graphite to be expected in selected places in the pile.

Technical report containing short reports on (1) Mass spectrometer studies; (2) Purification of heavy water; and (3) Equilibration studies.

Technical report abstract. A rapid procedure for the preparation of very pure carrier-free Zr and Nb tracer involves the chloroform extraction of the cupferrides of Zr and Nb activities from process solutions. Zr and Nb form very stable chloroform soluble cupferrides in acid solutions (CK-993) and are separated from other fission elements almost quantitatively to yield pure mixture of Zr and Nb activity. A minimum of operations is required and the method is easily adaptable to remote control.

Abstract: Experiments on colloid milling and pumping show that uranium trioxide, when carefully dehydrated, can be dispersed in water to form a relatively stable slurry, suitable for a homogeneous slurry pile. At temperatures considerably below those of anticipated pile operation particle size growth occurs attended by increase in settling rate and decrease in viscosity. Theses properties of the slurries may be strongly affected by impurities present as well as by special operating conditions.

Abstract. the electrodeposition of uranium metal, in the form of tree-like deposits, from molten strontium halide baths is described. Under the best conditions studied, approximately 40% recovery is attained. Freedom from side-reactions of the reduced uranium with anode products and/or refractory materials, and high cathode current densities appear to be essential to the success of the process. the refining of uranium under similar conditions appears to occur quite readily, with approximately 50% current efficiency. The preparation of UI3 is also described.

Abstract. Wigner effects on aluminum, beryllium, and tuballoy have been studied by the electrical resistance method. Samples were exposed during an interval which would have produced an increase of approximately 22% in resistance of AGOT-K graphite. The resistance of tuballoy increased approximately 1%. It is shown that the increase can be accounted for by the amount of fission product impurity formed during the exposure. Neither aluminum nor beryllium showed any change. In the case of Be, the Wigner effect may be obscured, to some extent, by the approximately .2 - .3 atom % of impurity present in the samples. Based on the increase occurring in ADOT-K graphite, a change of approximately .2 - .5 x10-6 ohm-om might be expected in the case of Be. The accuracy of the method was sufficiently great to detect a change of this magnitude. Other experiments with Be will be undertaken when purer samples are available. Meanwhile, some samples of the present type ae being subjected to further irradiation.

Abstract. A portion of the liquid-solid phase equilibrium region of the system U-UBr3 has been investigated by the method of thermal analysis. Uranium tribromide was prepared by introducing bromine vapor into a bulb containing finely divided uranium formed from the hydride. Cooling curves were obtained with tribromide and then with various compositions of tribromide and uranium. the information obtained showed that no solid sub halide exists but that the metal was soluble in the halide.

Six structural materials (aluminum 2S, aluminum 72S, copper, iron, steel, lead and bismuth) were irradiated for about 100 kilowatt hours in the center of the Argonne pile. The alpha and gamma decays were then followed for 130 days on Geiger counters and are presented here graphically as number of rays per minute per gram per kilowatt hour vs. time of decay. A quantitative interpretation of the gamma-ray decay curves gave fair agreement with the chemical analysis of impurities found in the materials.

The temperature coefficient of eta has been measured with the thermal column of the Argonne pile using uranium foils of different isotopic ratios. The temperature change was effected by filtering neutrons through silver. The measured fractional change per degree centigrade is [formula].

The present report is concerned with the electronic relay which, upon the reaching of a pre-determined value of ionization current in the associated chamber, actuates the safety rod release mechanism. The are here proposed two independent suggestions: (1) An improved trip circuit of such sensitivity and stability as to allow it to be actuated by a signal directly from the chamber without the necessity of interposing intermediate amplifier stages. The value of chamber current at which tripping occurs is stable to +- 0.4%. (2) A triple-wound relay to prevent shut-downs of the pile which would otherwise be caused by development of defects in the safety circuits.

The resonance absorption of a lump is described in terms of three components. Calculations of resonance absorption are carried out using the model for the resonance spectrum of uranium recently derived; calculations are also made with variations of this model which involve local fluctuations in level strengths. For metal and oxide lumps the agreement with observation is satisfactory. For dilute mixtures, whose resonance activation was measured by Mitchell, computed values fall 20% to 30% above measured ones.

It is usual to determine the density of neutrons by using foils of metals which become radioactive as a result of bombardment in the region under investigation. From the rate of disintegration of the newly formed radioactive element the number of neutrons absorbed can be calculated. By use of the capture cross section of the element of which the foil is composed the density of the neutrons can then be computed. By counting the alpha particles from a bismuth foil of known weight after exposure to neutrons the density of the neutrons which produced this activity can be calculated. The least accurately known value which enters into this evaluation is the capture cross-section of bismuth for pile neutrons. This value may be improved by future measurements. It is of importance only for absolute measurements of neutron density so that relative values can be measured with considerable accuracy on the basis of known data.

A good determination of the resonance absorption of uranium when admixed with various substances is necessary so that calculations can be made on the efficiency of homogeneous piles. The original experiments along these lines were undertaken by Creutz, Jupnik, and Snyder (C-116) and consisted of experiments on the resonance capture in pure U, UO2, U3O8, and one experiment on capture in a mixture of U3O8 and graphite. These experiments were done at the cyclotron in Princeton and consisted of determining the ratio of the twenty-three minute activity of uranium to an iodine monitor placed in some position with respect to the sample. By using spheres of different radii both the volume and the surface absorptions were measured. It was considered very desirable to extend these measurements to mixtures containing large amounts of graphite to uranium and also to investigate other substances containing hydrogen and deuterium. In addition it was decided to use both iodine and gallium monitors in the experiments. While the experiments were in progress, an absorption curve for uranium metal was made by Marshall using iodine and gallium detectors, which showed that there was a certain amount of overlapping of resonance levels of uranium and iodine.

Technical report with short reports from the (1) Experimental Nuclear Physics Group; (2) Theoretical Physics Group ; (3) Lattice Design Group; (4) Pile Design Group; (5) Exponential Experimental Group; (6) Radiation Group; and (7) Shielding Group.

It was desired to determine a method of evaporating boron to form a rather pure uniform tenacious coat of specified thickness. These coats are needed as monitoring films for neutron intensities, particularly in steel ionization cylinders. The most satisfactory method of evaporating boron employed a graphite filament. A mixture of amorphous boron and Carbenoid A was painted onto the filament which was then heated by electrical resistance method to 2300 degree C at which temperature the boron evaporated. Opaque films with purities up to 98% boron or better could be deposited by this method. Much heat was liberated by the filament, and it was found necessary to cool the steel cylinders during evaporation to prevent alloying of boron with the steel. Cathodic deposition also proved satisfactory for producing high purity films; this method has the advantage that little or no heat is produced during the process, but requires much time. Other less efficacious methods of depositing lighter films of born were developed; these are included in the following discussion.

Fermi, Anderson, and Nagle's experimental distribution of Indium resonance neutrons around a point source of fission neutrons in water has been fitted by analytic expressions which are source functions in the two-group, three-group, Fermi and Christy-Wheeler pile theory. The Christy-Wheeler function (exponential followed by a Gaussian) is the best fit; the two-group function (exponential) is slightly better than the Fermi Gaussian.

The change in the simple [formula] distribution of neutrons in a spherical lump of uranium caused by the distribution in velocities of thermal neutrons is calculated. If the calculated curve is fitted as well as possible by a simple [formula] curve, it is shown that the value of [formula] obtained in this way is a function of [formula], the radius of the sphere. For small radii the [formula] obtained in this manner will be as much as 25% greater than the [formula] corresponding to average velocity neutrons. The change in the thermal utilization caused by the distribution in velocities is discussed. The flux of neutrons into a sphere is calculated taking into account the velocity distribution and this is compared with the usual theory.