The pinhole neutron experiment is sometimes called ``Pinex``, a name which has also been used to describe the pin method of measuring the time required for imploding metals to travel to certain locations in space. The two experiments are not related and should not be confused with each other. The pinhole neutron experiment is very similar to the optical pinhole camera in which light passing through a pinhole in an opaque screen produces an inverted image of the source. In the pinhole neutron experiment 14 Mev neutrons from a thermonuclear device travel in straight.lines from their respective points of origin outward in all directions. Those which pass through a pinhole in an opaque neutron shield make an inverted neutron image of the source. Some of the neutrons which form the image are captured by threshold detector plates which have been suitably located behind the pinhole. Neutrons that have sufficient energy react with the nuclei of the detector plate to form radioactive nuclei that by their decay locate the position of the image on the plate. The image may be made visible by autoradiography or counting techniques. In the autoradiograph, an x-ray film is placed in contact with the image plate. …

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The development of new techniques of initiating nuclear weapons has amplified the requirement for an accurate knowledge of the probability of initiation as a function of the various parameters involved. The results of the codes presently used to calculate these probabilities are self-consistent, but have been shown to be quite sensitive to the value of fission cross section used. Accordingly the critical assemblies group vas requested informally by small weapons division to investigate the feasibility of providing a prompt critical assembly which could give an experimental basis for normalization of the code results. A study of the various assemblies which met the requirements of this experiment was therefore conducted to determine which was best suited. The conclusion of the study is that a bare spherical oralloy assembly similar in operation to that of the Los Alamos Godiva would be the most suitable device with which to make these measurements. This conclusion was based on the fact that the prompt critical behavior of such a bare oralloy sphere is well understood and further, this behavior can be calculated by means of the present weapons codes. Such an assembly could be in operation in less than six months and would require an …

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The radiators designated Cambridge #1 and #2 were visually examined and modified before operation. The initial examination revealed poor quality braze joints at the top and bottom plates of Cambridge #1. However, the same plates of Cambridge #2 were adequately brazed. The copper core of the fins was exposed in many of the tube-to-fin joints on both radiators, indicating that the braze material had not covered the fin collars. Samples were removed from each radiator and examined for evidence of mass transfer. Samples were also removed from the air inlet and outlet banks of both radiators and examined for fin-to-tube integrity.

The neocuproine colorimetric method was applied to the determination of copper in yttrium metal. From 5 to 80 - g of copper was determined in the presence of as much as 5OO mg of yttrium with a coefficient of variation of 2%. Copper was reduced to copper (I) with hydroxylamine and complexed with neocuproine (2,9-dimethyl-1,10-phenanthroline). The colored complex was extracted into chloroform and its absorbance measured, after dilution with ethanol, at 457 m - . (auth)

Several problems connected with vortex cavity reactors were studied analytically. They include, the generation of high-strength vortices by utilization of bleed through a porous tube wall to stabilize the shear layer on the wall; the nuclear criticality problem; the suitability of various compounds of plutonium as gaseous fissionable materials; and the problem of retaining the fission fragments within the vortex tube. It is concluded that the shear layer on the vortex tube wall can be stabilized if a mass flow greater than or equal to the vortex through flow is bled through the porous wall, and that the tangential Mach numbers which can be obtained are then slightly more than one-half the inviscid values. Beryllium oxide or graphite-moderated reactors of reasonable size and weight can attain criticality if the product of the hydrogen pressure in the vortex core and the maximum value of the ratio of fissionable gas density to hydrogen density in the tube is greater than about 100 atm. The reactor weights are then in the order of 10,000 lb or less. Of the several compounds of plutonium considered as gaseous fuel carriers, plutonium trifluoride and plutonium tribromide appear to be the most promising. It is probable that …

The reactivities of several U--Nb-- Zr alloys in the Sodium Reactcr Experiment are compared with that of 2.8% enriched U fuel. The alloys considered have the following compositions: 15% Nb--70% U--15% Zr; 12% Nb--82% U--6% Zr; and 6% Nb--82% U-- 12% Zr. Each alloy is studied at U enrichments of 3, 7, and 11%, and the alloy enrichments necessary to give the same reactivity as the 2.8% enriched U fuel are found by interpolation. (T.F.H.)

A method for the direct determination of uranium in a cyclohexane solution of tri-n-octylphosphine oxide (TOPO) is presented. The adduct, UO/sub 2/ Cl/sub 2/ x 2TOPO, that is formed when uranium(VI) is extracted from hydrochloric acid solutions by tri-n-octylphosphine oxide absorbs light in the ultraviolet region. This absorbance is measured at 230 m mu vs. a TOPO-cyclohexane solution that was contacted with hydrochloric acid of the same concentration as that in the test aliquot. The molar absorbance index is 5500. The method is not selective; of the elements that are extracted by TOPO from hydrochloric acid, iron(III), zirconium, molybdenum, tin and thorium, only thorium can be tolerated. (auth)

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Data obtained from testing and observing samples of 63S Al irradiated for approximately three months are presented. Tensile data show a slight, general increase in strength during pile exposure with a slight decrease in elongation. It is uncertain whether tkis increase in strength is a result of irradiation, exposure to slightly elevated temperatures, or a combination of the two effects. Metallographic examination revealed no apparent damage to the microstructure. As a result of these tests. it was determined that there is no daruage in the 63S Al samples caused by irradiation. (auth)

A concentration cell electrode was installed in a fritted glass surface and was used to measure the surface KCl concentration while water was being transpired through the surface into a mixed tank of 0.1 M KCl. The results from the first Fluorox run made with crude UF/sub 4/ showed that 85.3% of the theoretical amount of UF/sub 6/ was accounted for, with 17.9% being collected in cold traps and the remainder being consumed in various side reactions. Installation was completed of apparatus to study the electrolytic removal of nickel on an engineering scale from concentrated HRT fuel solution. An extremely low yield stress of 0.02 lb/sq ft was measured for a thoria-urania slurry containing 2.5 wt.% Al/sub 2/O/sub 3/ and spherical particles of 1.7 micron mean diameter. Preliminary data on the rate of uranium sorption on Dowex 21K from sulfate solutions were correlated with a simple spherical diffusion model. Laboratory scale studies to determine the effect of reflux time, HNO/sub 3/ concentration, and air sparge on chloride removal from APPR-type Darex dissolver product showed that an air sparge is definitely beneficial in chloride removal. Preliminary cyclic cleaning tests showed that boiling 25% caustic solution was adequate for cleaning type F …

The recent Windscale incident has emphasized the need for available light aircraft and proper instrumentation for aerial surveys following a release of large quantities of airborne radioactive materials. Early tests (1951 and 1955) are reviewed, and the program now in effect at the Oak Ridge National Laboratory is presented. (auth)

Eleven thorium-carbon alloys in the range 0.02 to 2.0% carbon were prepared by vacuum-arc melting. The hardness varied from 19 R/sub A/ for the 0.02% alloy to 108 R/sub B/ for the 2.0% alloy. The preparation of thorium- chromium alloy was hampered by a reaction with the zirconia molds, which results in porosity in the casting. The failure of aluminum-silicon bonded X-10 slugs after heat treatment for seven days at 400 deg C was traced to the failure to remove tin after the tin dip and the presence of a gas during heat treatment. Tensile tests were made on extruded thorium, and no correlation was found with extrusion variables. A composition effect was found, however, which showed a linear relationship between carbon content and tensile strength. Creep tests on thorium, uranium, and Inconel continue. The program of evaluating the variables in the fabrication of clad fuel elements, using MTR techniques was concerned mainly with the distribution of UO/sub 2/ in the core compact, the temperature of rolling, and the particle size of the metallic core powder. Progress is being made in the preparation of three-layer laminates without the use of a protective can during the hot-rolling operation but with the …

Studies of reflector control for the Advanced Engineering Test Reactor were made. The performance of various parts of the reflector control system model such as the safety reflector and the water jet educator, boric acid injection, and demineralizer systems is discussed. The experimental methods and results obtained are discussed. Four reflector control schemes were studied. The schemes were a single-region and three-region reflector schemes two separate reflectors, and two connected reflectors. Calculations were made of shim and safety reflector worth for a variety of parameters. Safety reflector thickness was varied from 7.75 to 0 inches, with and without boron. Boric acid concentration was varied from 100 to 2% of saturation in the shim reflectors. Neutron flux plots are presented (C.J.G.)

This report describes the design of the plant that was construrcted to remove insoluble fission and corrosion products from the circulating fuel solution of the Homogeneous Reactor Test (HRT). (auth)

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1. The r a t e s of photosynthesis and subsequent respiration of Chlorella pyrenoidosa were measured using an oxygen analyzer (sensitive to paramagnetism). The energy absorbed during the photosynthesis periods was determined and the quantum requirement was calculated. 2. Dark respiration r a t e was found to depend on the r a t e of light absorption during the period of photosynthesis, and increased with increasing photosynthesis rate. 3 . The quantum requirement, corrected for respiration, varied from 4. 9 ( a t a ratio of photosynthesis to respiration of 1.4) to 6. 9 (at a r a t i o of 12). Both uncorrected and corrected quantum requirements approach an experimental value of 7. 4 a t high light intensity. 4. The lower quantum requirement obtained a t low light intensity is believed to be due to a relatively greater importance of contribution of energy from respiration t o photosynthesis. An expression i s derived for the relation between this contribution and the enhancement of dark respiration due to the level of photosynthesis to which the plants a r e conditioned. 5. Attempts to obtain the blue -light stimulation of photosynthesis with algae photosynthesizing in r e …

This report covers studies of the excretion and retention of 'tracer' and toxic doses of the 11.2-day Ra{sup 223} isotope, its acute toxicity (organ weight changes, gross and microscopic pathology, and Fe{sup 59} utilization by the bone marrow), and long-term histopathological changes and alterations in the hemogram.

A brief survey of decarboxylation reactions and carboxylation reactions that are known or presumed in biological systems will be presented. While a considerable number of amino acid decarboxylations are known, their mechanisms will not be included in the present discussion but will be reserved for a later paper in the symposium. The remaining decarboxylation reactions may be subdivided into oxidative and nonoxidative decarboxylations. In most cases, these reactions are practically irreversible except when coupled with suitable energy-yielding systems. The carboxylation reactions which are useful in the formation of carbon-carbon bonds in biological systems seem to fall into two or three groups: those which exhibit an apparent ATP requirement, and those which exhibit a reduced pyridine nucleotide requirement, and those which exhibit no apparent ATP requirement. Of the first group at least four cases, and possibly six or seven, are known, and one interpretation of them involves the preliminary formation of 'active' carbon dioxide, generally in the form of a carbonic acid-phosphoric acid anhydride. Those exhibiting no apparent ATP requirement seem to be susceptible to classifications as enol carboxylations in which the energy level of the substrate compound is high, rather than that of the carbon dioxide. There appear to be …

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