Abstract: "The thermal and electrical conductivities of a series of Pu-Al alloys have been determined in the range 0.12 atomic percent Pu. The conductivities are approximately proportional to the volume of free aluminum."

Abstract: "The general utility of vacuum evaporated films is discussed. The characteristics that makes this technique most useful are the uniformity of the films, the easy control of their thickness over a large range, and the adaptability of the system to different metals and compounds. The design of a vacuum evaporator should provide adequate pumping speed, cooling of components, filament heater supply, and general flexibility and adaptability of the components to different materials. The design of filaments or boats and the evaporation of Al, Ag, Au, Li, Na, UCl4, ThF4, Be, SiO, Nal (Tl), U, and UO2 are considered. Special attention is given to the problem of obtaining uniform layers of UO2 on a large, flat target relatively close to the source."

The following report investigates part of the variability of the computed fall-out intensity patterns due to the variability of the winds, on the basis of winds from four Pacific shot days. An extreme case from Operation Sandstone is also considered.

Report discussing the effectiveness of various methods for removing plutonium from contaminated gloves. The cost of decontaminating the gloves using the most effective method was three times the cost of new gloves, and "consumer resistance" was noted among users of treated gloves.

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.

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.

The oxidation of uranium metal has been studied from the standpoint of the oxygen dependence of the reaction rate in an effort to establish the mechanism. The experimental data of Perkins agree with the theoretical dependence of the oxygen pressure derived this report. This agreement supports the hypothesis that the rate-controlling step in the migration of cations in the DO2 lattice, although the observed time dependence is not necessarily in agreement with this conclusion. Experimental entropies of activation are corrected for the observed pressure dependence. No firm conclusion could be reached as to whether the rate of diffusion or adsorption is rate-controlling.

The coefficient of linear expansion of alpha plutonium has been determined for the range -180 to +100 degree C by the silicon-tube and dial-indicator method. The value of the expansion coefficient is reported as [formula]. Included are a detailed description of the apparatus and a discussion of the method.

The coefficient of linear expansion of alpha plutonium has been determined for the range -180 to +100 degree C by the silicon-tube and dial-indicator method. The value of the expansion coefficient is reported as [formula]. Included are a detailed description of the apparatus and a discussion of the method.

Certain types of neutron diffusion calculations were considerably simplified when the Serber.Wilson Method was introduced about eight years ago. This method, semi-empirical In nature and named after its co-discoverers, was first formulated for the one-velocity isotropic theory and applied to spherical geometries. Within these limits it has in general proved to be a fairly accurate method. If restricted source-free case it has, in addition, turned out to be quite manageable both analytically and numerically.

Measurement of the color intensity of the uranium thiocyanate complex is discussed as a method for the quantitative determination of uranium. Two procedures for amounts from 1 microgram to 1 milligram are described, and standard curves are shown. The effects of numerous foreign ions are shown, and methods of removal for some of these are discussed.

It has been found that two silver atoms replace one polonium ion during the electrochemical exchange of polonium ion with silver metal. It is believed that the most probable exchange reaction may be described by the equation Po++ + 2Ag = Po + 2Ag+ . From the concentrations of polonium ion and Ag+ ion when the exchange reactions were terminated, calculations indicate Po = Po^ + 2e", E°< - 0.7.

The sample, water or urine, is prepared for counting in a vacuum line. Urine or water is dropped onto metallic calcium, and hydrogen and tritium are evolved. The gas flowing into the evacuated system is passed through liquid nitrogen cooled traps to remove unreacted water and condensable gases. The gas is allowed to flow into a tube similar to a Geiger-Muller tube until a pressure of 15 cm of mercury is attained. Ethylene and argon are added to give a total pressure of 22 cm of mercury. The beta activity is counted with a scaling circuit having an input sensitivity of 1/4 volt. A tube similarly filled with inert hydrogen is counted simultaneously to determine the environmental background. The background count is subtracted from the sample count to obtain the true sample count. The method has a precision of ± 5% in the range of 1 to 250 pc of tritium per liter of sample. Samples with higher concentrations may be determined with appropriate dilutions. An experienced operator can do approximately 50 determinations per day. The tolerance used at LASL for tritium in urine is 250 pc/liter.

A batch-type incinerator has been built which will dry and burn 12 liters of wet, packed rags or the equivalent in other organic matter in 8 hours. The material is ignited and burned in a stream of oxygen. Tars in the off-gas are trapped in a water bubble, residual contaminated particles are caught by a CWS filter, and acid vapors are reacted in a caustic scrubber. The unit was designed to processes plutonium residues; however, other radioactive materials could be handled by the use of appropriate shield and manipulators.

An analytical procedure for 0.04 to 1.6 percent ruthenium in plutonium metal was developed. Determination of ruthenium in metallic plutonium was investigated as part of a program for securing analytical procedures for various metals in plutonium. However, results of the investigation are given in this report with emphasis on the determination of ruthenium in plutonium chloride solutions. Specifically, this report is primarily concerned with the separation and determination of 40 to 400 micrograms of ruthenium in a hydrochloric acid solution of 25 to 100 milligrams of plutonium.

As an alternative to recovering Ba140 from the spent MTR fuel assemblies a new enriched-uranium fuel pin was designed for irradiation. Two specimens, each containing about 3 g. of uranium (93% enriched), were irradiated to 1.3% and about 18% burnup. Examination after irradiation indicated that design improvements were needed; photographs are presented to illustrate the damage incurred during irradiation. A simple inorganic chemical process using precipitation and filtration techniques was developed to separate Ba140 from other fission products and uranium.

Recent measurements on the long counter efficiency in which comparisons were made with the (n, p) scattering cross section, additional variations in efficiency were found which varied slowly with neutron energy but were still correlated with the total neutron cross section of carbon. Because of these variations in efficiency there are errors in the fission cross sections reported in LA-1714. Corrections to these data have been given here.