The spontaneous fission rate of plutonium-240 has been redetermined and found to be 1.51 X 106 events/g/hr.

Field tests were conducted to measure short-period pollutant concentrations at several stack heights during conditions of marked atmospheric instability and low wind speeds. The source was a mechanical smoke generator located at the 185-ft level of a tower.

A manipulator designed to support an irradiated slug at the bottom of the viewing basin, so that an operator could view it through a binocular telescope and be able to see all surfaces, was designed. Hydraulic power, using water, operates the manipulator and gears.

The corrosion resistance of four types of austenitic stainless steels to Purex process first and second acid concentrator bottoms was determined. Although the compositions of the two solutions were very similar, tests in simulated solutions of both compositions were conducted to strengthen the basis for the conclusions which were to be made.

Measurements were taken to provide experimental evidence for determining the feasibility of a proposed method for converting Pu240 to 241 by exposing shielded plutonium to selectively transmitted pile neutrons.

During the canning of slugs for Production Test 313-105-3-M, a high number of rejects were caused by gas voids in the A1-S1 bonding layer. Since the heat treatment of the slugs in a molten salt bath resulted in a chemically altered surface, an investigation was made to determine the volume of gas evolved from salt-bath heat-treated slugs as compared to other types of slugs. This test was designed as a preliminary test to determine if there were a significant differences.

Two xenon extraction runs were made this month. It appears that a small design change in Trap #2 will be necessary so that a dry ice-trichloroethylene slurry can be used for coolant rather than liquid freon. For each of the runs this month the enriched generator was exposed for four hours in the est pile operating at 100 watts. A period of eight hours for cooling and xenon builidup was allowed before the collection and separation runs were started.

Hanford uranium contains minute angular inclusions which affect the microstructure, reactivity, and other important factors controlling the serviceability of the metal. Small quantities of the inclusions have been isolated by chemical means, and the x-ray diffraction patterns and chemical analyses of the isolated materials have been determined. As a first step in the identification of the inclusions present in rolled uranium, a search was made for a chemical method of separating the inclusions from the matrix metal.

Interest has been expressed in continuously monitoring the beta activity of the uranyl nitrate solution pumped to the RCU receiver tank, to facilitate operation at higher flow rates and with younger feeds. A beta scintillation detector has been developed which should make this feasible, and it is proposed that it be tested on stream for this use.

Removal of particles from air is discussed in terms of three classes of filtering media--air-sampling, respirator, and air-cleaning. Plots of efficiency versus filtering velocity are presented. The pressure drop characteristics of the filters are discussed in terms of initial pressure drops of the clean filters, variations in pressure drop of the individual filters, and comparison of loading rates.

The remodeling, fabrication, and instrumentation of a high vacuum system are described. The faults encountered with the old system and their solution are outlined. Tests were made on diffusion pump oils and on the reduction of pump oil back diffusion. The measurement of high vacuum pressures by a cold cathode ionization gage at various points on a vacuum system are discussed.

Several improvements have been made in the gamma scintillation counter (GSC). The Model V gamma scintillation counter uses a canned thallium activated sodium iodide crystal as a detector. Although the electronic components remain unchanged, a modification of the sample support has been made to improve reproducibility of geometry. To assure comparable results between various counters, they must be operated at the same energy threshold and counting yield. Methods have been developed to assure operation at a preferred energy threshold of 0.1 Mev and an arbitrarily fixed counting yield of 3.36% for Cs-Ba-137. Partial pulse height discrimination against U 237 is also accomplished.

The results of electrical resistance measurements have been used as a means of following changes occurring in metals due to irradiation. The electrical conductivity is sensitive to changes in composition and to cold-work or structure damage. In an anisotropic metal, such as uranium, the director of measurement also influences to some extent the values obtained. For these reasons it is essential to use the same material, and if possible the same piece of material, in comparing the electrical properties before and after irradiation. This report is a description of the measurements made on pieces of the same uranium rod before and after an exposure of approximately 150 MWD/T. The results, while preliminary in nature and dealing only with one sample and exposure level, provide data for which a comparison may be made of the electrical resistivity of irradiated and non-irradiated uranium metal.

For some time, the need has been recognized for an X-ray diffraction unit applicable to studies concerning the crystallographic characteristics of pile irradiated materials. Except for studies involving specimens of low activity, it has been impossible in the past to investigate materials which emit intense beta and gamma radiations. The exact type and degree of irradiation damage to high activity materials has been largely a matter of theoretical conjecture. The object of this report is to describe an X-ray diffraction spectrometer that can be used to collect crystallographic data from irradiated materials.

When an aqueous solution containing dissolved irradiated uranium and nitric acid is equilibrated with 30% tributylphosphate solution in kerosene, the distribution co-efficients for sirconium and niobium are decreased by the addition of phosphoric acid to the system.

The decontamination of portable instruments by the Calibration Unit has presented a problem for some time. Most of the contamination is in the 100 to 500 c/m or 500 to 2000 d/m range. Higher levels of contamination can usually be reduced to these levels, but further cleaning proves quite difficult

Three types of stainless steel (309 SCB, Carpenter 20, 304-L) were exposed to both the liquid and vapor phase of each of three types of solutions. The time of exposure totaled ten days during which the specimens were cleaned and weighed periodically. The three synthetic D-12 waste solutions contained respectively chrome-high chloride, chrome-low chloride and high chloride sans chromium. The solutions were renewed at each weighing.

The first of two general methods are discussed based on the removal of the thin layer of aluminum to which graphite adheres. Two electro-polishing techniques, an electrolytic etch, an anodization-deanodication cycle and two chemical etches are described.

An improved method for the determination of boron in plutonium is reported. Precipitation of plutonium (III) acid oxalate prior to color development with curcumin results in increased precision, greater speed, and lower costs. Results are presented of a statistical study involving all variables.

Impurities are separated from plutonium solutions by means of TTA (thenoyltrifluoracetone) extractions. Plutonium in hydrochloric acid solution is reduced to the trivalent state with hydroxylamine, and some impurities are extracted into hezone or a solution of TTA in hezone. The organic phase is removed, and the plutonium in the aqueous phase is oxidized to the tetravalent state with nitric acid. Investigations of several variables which affect the extraction are described..

The construction and operation of a fission gas generator, containing about 25 grams of uranium in the form of a powder with a high specific surface, are described in detail. The purpose of the work discussed in this report was to examine the feasibility of producing, separating, and assaying samples of Xe135 in preparation for a proposed measurement of the neutron cross section of this isotope. Krypton and xenon are separated by selective adsorption on charcoal at reduced temperature while iodine is removed by charcoal sorption at room temperature.

In 1949 Barad presented two solutions to the general diffusion equation. Basic in both solutions is the assumption that in very stable atmospheres a point source may be replaced by a vertical area of uniform concentration at a short distance downwind. This vertical area is considered to exist at the distance at which the plume finally "levels-off" and assumes a flat ribbon-like appearance. In addition if the distance over which diffusion takes place is limited to one or two miles and if only the stable atmosphere with its narrow range of eddy sizes is considered, the average diffusion co-efficient (K) has a signficance which it does not have in the case of neutral equilibrium.

In obtaining the results reported here a double focusing magnetic type spectrometer was used. Momentum spread was about 1%, and in most cases 2560 counts per point were taken. An end window Geiger tube was used as a detector. The window was of mica with areal density of 1.6 mg/cm2.

Various organizations in the Biophysics Section of the Radiological Sciences Department participated in evaluating local radioactive particle fallout as influenced by the nuclear explosions at the Nevada Proving Grounds during the early part of 1953. Data collected from approximately 50 air monitoring stations operated by the Regional Survey forces were used to determine the trend of radioactive particle concentrations in the atmosphere between March and June. These measurements were supplemented with the findings of associated organizations in the Biophysics Section during and immediately after the peak influx on May 26.