232 Matching Results

Search Results

Advanced search parameters have been applied.

RECOVERY OF URANIUM FROM AMINE EXTRACTANTS WITH AMMONIUM CARBONATE

Description: An economical process was developed through benchscale experiments for recovering uranium from amine extractants with ammonium carbonate solution. By recycling the strip solution to allow build-up in the concentration of ammonium sulfate (formed in the stripping reactions) to 1-2M, the solubility of uranium in the aqueous phase was limited to <5 g/liter and ammonium uranyl tricarbonate (AUT) precipitated in the stripping system. The AUT, which settled and filtered rapidly, was readily converted to U/sub 3/>i by calcination at 5OO deg C, yielding a high assay (>97% U/sub 3/O/sub 8/) concentrate virtually free of sodium, molybdenum, and vanadium. Estimated reagent costs for the strippingprecipitation step were 7 cent per pound of U/sub 3/O/sub 8/. (auth)
Date: March 1, 1961
Creator: Hurst, F.J. & Crouse, D.J.
Partner: UNT Libraries Government Documents Department

IN-PILE CORROSION TEST LOOPS FOR AQUEOUS HOMOGENEOUS REACTOR SOLUTIONS

Description: An in-pile corrosion test loop is described which is used to study the effect of reactor radiation on the corrosion of materials of construction and the chemical stability of fuel solutions of interest to the Aqueous Homogeneous Reactor Program at ORNL. Aqueous solutions of uranyl sulfate are circulated in the loop by means of a 5-gpm canned-rotor pump, and the pump loop is designed for operation at temperatures to 300 ts C and pressures to 2000 psia while exposed to reactor radiation in beam-hole facilities of the LITR and ORR. Operation of the first loop in-pile was begun in October 1954, and since that time 17 other in-pile loop experiments were completed. Design criteria of the pump loop and its associated auxiliary equipment and instrumentation are described. In-pile operating procedures, safety features, and operating experience are presented. A cost summary of the design, fabrication, and installation of the loop and experimental facillties is also included. (auth)
Date: December 21, 1960
Creator: Savage, H.C.; Jenks, G.H. & Bohlmann, E.G.
Partner: UNT Libraries Government Documents Department

The Adsorption Of Uranium From Solutions By Activated Carbon

Description: Experimental results on the adsorption of U from solutions by activated C indicate that low pH values reduce the adsorption and that a marked change occurs in the adsorption of U(VI) at pH2. Under a given set of conditions the adsorption of U follows a typical Freundlich isotherm. The particle size of the charcoal affects the rate of adsorption but not the amount of U adsorbed at equilibrium. The temperature coefficient of adsorption is negligible, and the adsorption of U from uranyl solutions is a reversible process. (BJH)
Date: August 15, 1949
Creator: Goodrich, J.C.
Partner: UNT Libraries Government Documents Department

RECYCLE OF UO$sub 2$F$sub 2$ IN THE FLUOROX PROCESS: REACTION OF UO$sub 2$F$sub 2$ WITH HYDROGEN

Description: The reaction of U0/sub 2/F/sub 2/ with hydrogen at 700 to 850 deg C was briefly investigated since it could constitute a major step in the recycle of U0/ sub 2/F/sub 2/ in the Fluorox process. The reaction in this temperature range proceeds according to the equation U0/sub 2/F/sub 2/ + H/sub 2/ yields U0/sub 2/ + 2 HF. Rates of the chemical reaction were not obtsined, since, with the thermogravimetric technique used, the rate-controlling process was bed diffusion. However, there is no doubt that the rate of chemical reaction is sufficiently high for the desired application. No significant amount of UF/sub 4/ was formed by the back-reaction, U0/sub 2/ + 4 HF yields UF/sub 4/ + 2 H/sub 2/0. (auth)
Date: July 1, 1959
Creator: Ferris, L.M. & Gardner, R.P.
Partner: UNT Libraries Government Documents Department

Composition for detecting uranyl

Description: The present invention relates to an indicator composition for use in spectrophotometric detection of a substance in a solution, and a method for making the composition. Useful indicators are sensitive to the particular substance being measured, but are unaffected by the fluid and other chemical species that may be present in the fluid. Optical indicators are used to measure the uranium concentration of process solutions in facilities for extracting uranium from ores, production of nuclear fuels, and reprocessing of irradiated fuels. The composition comprises an organohalide covalently bonded to an indicator for the substance, in such a manner that the product is itself an indicator that provides increased spectral resolution for detecting the substance. The indicator is preferably arsenazo III and the organohalide is preferably cyanuric chloride. These form a composition that is ideally suited for detecting uranyl.
Date: January 1, 1994
Creator: Baylor, L.C. & Stephens, S.M.
Partner: UNT Libraries Government Documents Department

Optical apparatus and method for sensing uranyl

Description: An optical sensing device for uranyl and other substances, a method for making an optical sensing device and a method for chemically binding uranyl and other indicators to glass, quartz, cellulose and similar substrates. The indicator, such as arsenazo III, is immobilized on the substrate using a chemical binding process. The immobilized arsenazo III causes uranyl from a fluid sample to bind irreversibly to the substrate at its active sites, thus causing absorption of a portion of light transmitted through the substrate. Determination of the amount of light absorbed, using conventional means, yields the concentration of uranyl present in the sample fluid. The binding of uranyl on the substrate can be reversed by subsequent exposure of the substrate to a solution of 2,6-pyridinedicarboxylic acid. The chemical binding process is suitable for similarly binding other indicators, such as bromocresol green.
Date: January 1, 1994
Creator: Baylor, L.C. & Buchanan, B.R.
Partner: UNT Libraries Government Documents Department

Retention of neptunium in uranyl alteration phases formed during spent fuel corrosion

Description: Uranyl oxide hydrate phases are known to form during contact of oxide spent nuclear fuel with water under oxidizing conditions; however, less is known about the fate of fission and neutron capture products during this alteration. We describe, for the first time, evidence that neptunium can become incorporated into the uranyl secondary phase, dehydrated schoepite (UO{sub 3}.8H{sub 2}O). Based on the long term durability of natural schoepite, the retention of neptunium in this alteration phase may be significant during spent fuel corrosion in an unsaturated geologic repository.
Date: September 1, 1997
Creator: Buck, E.C.; Finch, R.J.; Finn, P.A. & Bates, J.K.
Partner: UNT Libraries Government Documents Department

Retention of neptunium in uranyl alteration phases formed during spent fuel corrosion

Description: Uranyl oxide hydrate phases are known to form during contact of oxide spent nuclear fuel with water under oxidizing conditions; however, less is known about the fate of fission and neutron capture products during this alteration. We describe, the first time, evidence that neptunium can become incorporated into the uranyl secondary phase, dehydrated schoepite (UO{sub 3}{lg_bullet}0.8H{sub 2}O). Based on the long-term durability of natural schoepite, the retention of neptunium in this alteration phase may be significant during spent fuel corrosion in an unsaturated geologic repository.
Date: October 1, 1997
Creator: Buck, E.C.; Finch, R.J.; Finn, P.A. & Bates, J.K.
Partner: UNT Libraries Government Documents Department

Corrosion mechanisms of spent fuel under oxidizing conditions

Description: The release of {sup 99}Tc can be used as a reliable marker for the extent of spent oxide fuel reaction under unsaturated high drip rate conditions at 90{degrees}C. Evidence from the leachate data and from scanning and transmission electron microscopy (SEM and TEM) examination of reacted fuel samples is presented for radionuclide release, potential reaction pathways, and the formation of alteration products. In the ATM-103 fuel, 0.03 of the total inventory of {sup 99}Tc is release in 3.7 years under unsaturated and oxidizing conditions. Two reaction pathways that have been identified from SEM are (1) through-grain dissolution with subsequent formation of uranyl alteration products, and (2) grain-boundary dissolution. The major alteration product identified by X-ray diffraction (XRD) and SEM, is Na-boltwoodite, Na[(UO{sub 2})(SiO{sub 3}OH)].H{sub 2}O, which is formed from sodium and silicon in the water leachant.
Date: September 1, 1997
Creator: Finn, P. A.; Finch, R. J.; Buch, E. C. & Bates, J. K.
Partner: UNT Libraries Government Documents Department