Most books on the subject of gas discharges describe the multiple banded structure which appears in the flow between two electrodes. This structure is actually due to the difficulty in getting electrons out of the cathode to support the discharge. These electrons are obtained by having a large enough potential drop near the cathode so that the positive ions may strike it hard enough to product secondary electrons. If one substitutes a hot cathode to produce a copious quantity of electrons, the banded structure will be radially changed. Hence the banding is not a pure property of the discharge, but is a complication brought on by the presence of electrodes.

Bismuth analytical methods were investigated for the purpose of selecting procedures which are satisfactory for the analysis of solutions containing plutonium and bismuth. The gravimetric procedure which is recommended for samples containing these two elements includes removal of the plutonium by peroxide precipitation, separation of the bismuth by precipitation with sodium carbonate, and final ignition of the bismuth as a phosphate. Necessary equipment and experimental technique are described. In the analysis of eight known samples by the recommended method, the average recovery of bismuth was 99.76 percent, with a standard deviation of 0.22 percent. The known samples contained about 35 mg of bismuth and 25 mg of plutonium. For similar samples in routine work, the confidence limits at the 95 percent level for the average of triplicated determinations are +- 0.30 percent of the bismuth in the the sample. Other methods investigated and having possible application for some Pu-Bi analysis problems include electrodeposition of bismuth on a mercury cathode and gravimetric analysis with BiCr(CNS)6 as the weighed product.

Determination of cadmium in plutonium-cadmium solutions was successfully accomplished by separating the plutonium as an insoluble peroxide, evaporating the solution containing the cadmium, and weighing the latter as a sulfate. with 5 t0 20 mg of cadmium and similar amounts of plutonium, the 95% confidence limits for the average of triplicate determinations was to be +- 0.3 percent of the cadmium in the sample. When samples contained as little as 5 mg of cadmium, it was necessary to correct the weight of cadmium sulfate with a carefully determined reagent blank which originated mainly from the action of hydrogen peroxide on glass containers.

A search for gamma-ray activities with period 1-100 msec from thermal neutron fission of U235 gave negative results. 0.43 +- 0.03 sec was the shortest observed. The period of B12 was found to be 27 +- 3 msec. The cyclotron beam was pulsed to supply 1-10 msec neutron bursts. coincidence scintillation deters were employed.

The production yields of hydrazine by various ionization methods are compared. The maximum value of M/N (number of molecules reacting per ion pairs) for electric discharge was 0.25 and for beta particles on liquid ammonia, M/N = 0.31. A 1-Mev reactor could produce 1.6 kg of hydrazine per hour if M/N = 0.04 as determined by alpha particles on liquid ammonia. About 300 ev of energy were needed to form a hydrazine molecule. (C.J.G.)

The results of a series of neutron diffusion calculations relating to an untamped Orally sphere are presented in detail in this report. The three-velocity neutron transport theory was taken as the basis for the analytical work preceding the computations. This particular theory, also known as the transport approximation, is defined in LA-1271 and known to be quite accurate for assemblies primarily involving materials of large atomic weight. For a sphere of uniform density and atomic composition the transport theory has another advantage. It can readily be formulated in terms of simultaneous integral equations (in our case three), relatively simple in form, involving the collision densities [formula] and a set of parameter values describing the materials. Nb(r) is , as indicated, a function of the radial distance [formula] and the velocity index g, g - 1, 2, 3. The parameters, fifteen in number for the three-velocity theory, are comprised of the velocities, the inverse mean free paths, and the transfer coefficients.

Uranium has been successfully impact extruded into typical cylindrical shapes of conventional design. Extrusion was carried out in the "gamma" region by heating cast uranium slugs to a temperature of approximately 1050 degrees C. Protection against oxidation was afforded by surrounding the slugs during heating with an inert atmosphere of argon gas. Impact extruded shapes possessed physical properties which are better than the properties of as-cast metal. Also, extruded shapes show a uniform internal structure with flow lines characteristic of commercial impact extruded pieces formed from other metals. Impact extrusion, as a fabricating processes for uranium, maybe applied successfully to produce complicated shapes or forms not practical by casting or where savings in metal and machining time is desired. The process would not appear to be commercial unless a large quantity of pieces was required.

Exponential rise times, T, of neutron flux in an Oy-Tu assembly have been measured for a set of points essentially equally spaced reactivity-wise in the interval between delayed and prompt critical corresponding to [infinity] > T > 5 seconds. The relationship between positive period and reactivity thus obtained is used to decide (preferentially) between two currently used but divergent collections of delayed neutron data, specifically with respect to the relative abundances of delayed neutrons in the different decay periods. Results of other reactivity measurements supplementing the positive period data are also given.

The pressure and temperature cycles developed during the bomb reduction of uranium tetrafluoride by calcium have been determined. Data for the 250, 500, and 1000 gram scale reductions are given, and the apparatus used is described.

Design and construction of remote control equipment for plutonium metal production are described. Criteria for the design of the equipment included the following: rubber gloves were to be completely eliminated; all mechanisms were to be built as integral units to facilitate replacement through use of the plastic- bag technique; no accessory equipment such as switches, valves, piping, or cylinders were to be inside the contaminated enclosure unless required to handle the plutonium; and all units were to be tested in mockups before final design. The chemical process, general layout, and operating function are outlined. Descriptions are given of all mechanical units, electrical systems, hydroxide slurry systems, ventilation systems, and chemical tanks and manifolds. (W.L.H.)

Abstract: "Decontamination factors of the order of 10-4 were obtained for Beta and Gamma emitters present as fission products when uranium was precipitated from 50 mC activity level solutions as uranyl oxalate under normal uranium yield conditions for three cycles (~60%). Factors of the order of 10-3 were obtained by the use of this reaction with similar solutions under relatively high uranium yield conditions for three cycles (~90%). The uranium peroxide precipitation reaction proved to be of no value on such solutions, yielding decontamination factors of only 17.1 Beta emitters and 1.2 for Gamma emitters for three cycles."

A spectrophotometric method for the determination of plutonium wing sodium alizarin sulfonate has been developed. The red plutonium-alizarin sulfonate color is developed in solutions having a pH of about three in the presence of a formic acid-sodium formate buffer, and the resulting absorption is measured at 530 millimicrons. Most interfering cations, particularly iron(III), are removed from the plutonium solutions by means of electrolysis using a mercy cathode. Aluminum(III), in quantities up to 3 percent of the plutonium content, may be tolerated in this procedure. Chloride and nitrate ions produce no interference over the concentration range studied, while tartrate, citrate, oxalate, and fluoride ions cause low results. The analysis of a large series of pure plutonium solutions, ranging from about 25 to 150 micrograms of plutonium in 10 milliliters, have a standard deviation of 0.92 percent for the determined plutonium content.

The relative physiological and toxicological properties of americium and plutonium have been studied following their intravenous administration to rats. The urinary and fecal excretion of americium was similar to that of plutonium administered as Pu(N03)4. The deposition of americium the tissues and organs of the rat was also similar to that observed for plutonium. The liver and the skeleton were the major sites of deposition. Zirconium citrate administered 15 minutes after injection of americium increased the urinary excretion of americium and decreased the amount found in the liver and the skeleton at 4 and 16 days. LD305° studies showed americium was slightly less toxic when given in the acute toxic range than was plutonium. The difference was, however, too slight to be important in establishing a larger tolerance dose for americium. Survival studies, hematological observations, bone marrow observations, comparison of tumor incidence and incidences of skeletal abnormalities indicated that americium and plutonium have essentially the same chronic toxicity when given on an equal basis. These studies support the conclusion that the tolerance values for americium should be essentially the same as those for plutonium.

It has been found relatively easy to form uranium in the gamma phase temperature range by hot pressing, forging, or extrusion. The metal is quite plastic and flows readily to form a shape. Several temperatures from 800 degree C to 1000 degree C were investigated. No forming difficulties were experienced with the metal at the several temperatures concerned. The major difficulty in gamma phase hot pressing or extruding was associated with the tools. Metals or ceramics were not successful as tools for one or more reasons concerned with: lack of hot strength, reactions with the uranium, failure in thermal shock, and tendency to spall. Graphite was found to be the best material available, but it is not entirely satisfactory because of low strength. Uranium formed in the gamma phase possesses some refinement of grain structure as compared with as-cast metal; however, the grain size is quite large. No physical properties of the gamma phase formed metal were determined.

Critical mass of an Oy (93.9%) sphere in graphite is given as a function of graphite tamper thickness. It was shown that approximately 20(in) of graphite is effectively infinite and that the approximately 17(in) used herein is approximately 98% infinite. Critical mass measurements of Oy (93.9%) spheres and cylinders of different diameters are given for approximately 17(in) graphite tamper, for effectively infinite paraffin tamper, and for effectively infinite water tamper. From these measurements cylindrical shape factors were computed. Both shape factors and critical masses are shown in Figs. 22 and 23 as function of the critical height to diameter rate of the cylinders.

Experimental techniques are described for the spectral measurement of a collimated fast neutron beam. A hydrogen filled cloud chamber, proton recording nuclear plates, and threshold fission foils were used as neutron detectors in the measurements. As an application of the above technique, the energy distribution and absolute flux of the fast neutron beam emerging from port 5W of the Los Alamos fast rector has been measured from 0.1 Mev to 18 Mev. The result show a spectral curve possessing a maximum between 9.25 and 0.30 Mev and having an exponential decrease at energies above 1.5 Mev. The mass energy of the distribution is at 0.55 Mev and the slope of the exponential section is 3.1 - 0.1 Mev per decade of intensity decrease.

An accidental burst of radiation occurred at the laboratory on 1 February 1951 during remote control operation of a critical experiment. There was no personnel hazard. Normal operations were resumed within 24 hr, and the active material involved in the burst returned to service within three weeks. An unforeseen brief excursion into the prompt critical region was engendered in the act of scramming the assembly at the end of a series of measurements. This report describes the effects of the burst and analyzes the probable causes in some detail.

Abstract: An appraisal is made of the radiologic hazard created by a 1000-ft. high air burst of a nominal sized nuclear bomb. Three sets of graphs are included which show the relations between dose rate (milliroentgens per hour), time post-shot, and distance from Ground Zero for a soil having given constituents. Estimates are given for fall-out activity (gamma) for distances up to about 200 miles from Ground Zero immediately after fall-out. It is pointed out that the radiologic hazard due to fall-out in the example cited is insignificant; further, that the radiologic hazard from similar nuclear bombs bursting at different heights above the ground will vary to a considerable extent.

A polarographic method for the determination of titanium in the presence of plutonium has been devised. Hydrochloric acid solutions of plutonium and titanium are reduced with zinc, made one molar in tartaric acid, and further reduced in the polarographic cell with liquid zine amalgam. Plutonium is thus reduced to the non-interfering (III) oxidation state and a well defined anodic wave for the oxidation of titanium (III) to titanium (IV) is obtained. The height of this wave is directly proportional to the titanium concentration for plutonium-titanium solutions containing 20 grams plutonium per liter. The precision for the analyses of duplicate samples has been calculated at the 95 percent confidence level to be 2.9 percent for those containing 0.025 to 0.050 gm titanium per liter and 1.1 percent for those containing 0.089 to 0.51 gm titanium per liter.

Strubl's polarographic method for the determination of uranium in the presence of iron can be used for the determination of uranium in plutonium solutions. A hydroxylamine hydrochloride solution (2M) is used as the supporting electrolyte. This reduces the plutonium to the plus three oxidation state without reducing the uranium. The uranium may then be determined polarographically by measuring the height of the uranyl reduction wave (UVI to UV) at -0.35 volts (vs. S.C.E.) applied potential. Solutions with a U/Pu weight ratio as low as 3.5 x 10(-3) were analyzed with an error of less than 2%. This error increased to 6% for solutions of 1 x 10(-3) U/Pu ration and is considerably larger for smaller U/Pu ratios.

The total cross sections of the reactions DDp, DDn, TD at 10 kev to 10 Mev are estimated from a review of the experimental data up to January 1951. Maxwell averages for DDp and TD computed from these estimates are given, together with some fitted analytic expressions provided for machine use. A collection of the identifiable earlier estimates is also included for reference and for comparison with the new figures. For relative order of magnitude purposes, cross sections and the derived Maxwell averages are given down to 50 ev using the theoretical Gamow slopes for the extrapolation. Gamow plots for the derived cross sections above l0 kev arc also given. Much of the primary experimental data exists in the form of thick target yields and we find the most uncertain factor in converting these thick targets yields into cross sections is the magnitude of the D/sub 2/O stopping cross section. The particular D/sub 2/O stopping cross section relation used in this derivation together with some of the earlier stopping cross sections are given. Thick target yields are included for both DD and TD on D/sub 2/ targets, at 0.01 to 1 Mev, experimental values being supplemented by calculated values.

Report discussing the reaction of uranium with pure water. The reaction was followed by using a method of measuring hydrogen evolution.

A tentative nickel-plutonium constitutional diagram was based on data obtained by thermal analysis, metallography, and x-ray-diffraction techniques. The systema is a complex one with the following important features. Nickel is soluble in epsilon plutonium, extending the epsilon field to 4.3 at.% nickel at 465 deg C. Nickel and plutonium form six intermetallic compounds, PuNi, EnNi/sub 2/, PuNi/sub 3/, PuNi/sub 4/, PuNi/sub 5/, and PuNi/sub 9/. The compound PuNi/ sub 5/ forms congruently from the melt at approximately l300 deg C, whereas the other compounds form peritectoidally. The extended epsilon field terminates in a eutectoid reaction at 415 deg C and l.5 at.% nickel. Epsilon plutonium and the compound PuNi form a eutectic system at 465 deg C with a eutectic composition of l2.5 at,% nickel. Nickel and the compound PuNi/sub 9/ form a eutectic system at l2l0 deg C with a eutectic composition of 92 at.% nickel. Plutonium forms a limited solid solution with nickel.