Feasibility of conversion of uranyl nitrate to uranium trioxide by the continuous addition of concentrated uranyl nitrate solution to hot, agitated UO3 powder.

From introduction: "Five appendices, each of which pertains to a separate phase of the Filtration of Radioactive Aerosols by Glass Fibers program."

Thermal spikes occurring during the life of a slug in a pile cause a momentary destruction of the original configuration of atoms in the metal. This process occurs at such a rate that in a thermal neutron flux of 10(13) neutrons per square centimeter per second each atom in the metal will be subject to temperatures above the melting point of uranium every 40 minutes.

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.

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.

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.

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.

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.

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

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.

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.

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 uranium recovery processes which are in operation or under construction at the present time--TBP, Redox and Purex--yield an aqueous uranyl nitrate solution as the recovered uranium product. For conversion of this recovered uranium to UF6 for feed to the gaseous diffusion plants, the uranyl nitrate in the solution is concentrated with or without prior organic stripping, calcined to UC3, reduced to UO2 with hydrogen, hydro-fluorinated to UF4 with RF, and finally fluorinated to UF6 with elemental fluorine.

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.

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.

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 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.

The effects of oxidation and irradiation on the microsurface structure of pile graphite have been investigated by measuring the surface area and pore size distribution of several samples. The results obtained for both oxidized and irradiated graphite samples indicate that changes in surface characteristics which occur are determined by the flux, temperature of irradiation, and gaseous atmosphere in which the radiation takes place.

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.