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1

Uranium dioxide electrolysis  

DOEpatents

This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

Willit, James L. (Batavia, IL); Ackerman, John P. (Prescott, AZ); Williamson, Mark A. (Naperville, IL)

2009-12-29

2

Transport properties of uranium dioxide  

SciTech Connect

In order to provide reliable and consistent data on the thermophysical properties of reactor materials for reactor safety studies, this revision is prepared for the transport properties of the uranium dioxide portion of the fuel property section of the report Properties for LMFBR Safety Analysis. Since the original report was issued in 1976, measurements of thermal diffusivity and emissivity have been made. In addition to incorporating this new data, new equations have been derived to fit the thermal diffusivity and thermal conductivity data. This analysis is consistent with the analysis of enthalpy and heat capacity. A new form of equation for the emissivity is also given. The present report comprises the transport part of the UO/sub 2/ portion of section A of the planned complete revision of Properties for LMFBR Safety Analysis.

Fink, J.K.; Chasanov, M.G.; Leibowitz, L.

1981-04-01

3

Thermodynamic properties of uranium dioxide  

SciTech Connect

In order to provide reliable and consistent data on the thermophysical properties of reactor materials for reactor safety studies, this revision is prepared for the thermodynamic properties of the uranium dioxide portion of the fuel property section of the report Properties for LMFBR Safety Analysis. Since the original report was issued in 1976, there has been international agreement on a vapor pressure equation for the total pressure over UO/sub 2/, new methods have been suggested for the calculation of enthalpy and heat capacity, and a phase change at 2670 K has been proposed. In this report, an electronic term is used in place of the Frenkel defect term in the enthalpy and heat capacity equation and the phase transition is accepted.

Fink, J.K.; Chasanov, M.G.; Leibowitz, L.

1981-04-01

4

Anisotropic thermal conductivity in uranium dioxide.  

PubMed

The thermal conductivity of uranium dioxide has been studied for over half a century, as uranium dioxide is the fuel used in a majority of operating nuclear reactors and thermal conductivity controls the conversion of heat produced by fission events to electricity. Because uranium dioxide is a cubic compound and thermal conductivity is a second-rank tensor, it has always been assumed to be isotropic. We report thermal conductivity measurements on oriented uranium dioxide single crystals that show anisotropy from 4?K to above 300?K. Our results indicate that phonon-spin scattering is important for understanding the general thermal conductivity behaviour, and also explains the anisotropy by coupling to the applied temperature gradient and breaking cubic symmetry. PMID:25080878

Gofryk, K; Du, S; Stanek, C R; Lashley, J C; Liu, X-Y; Schulze, R K; Smith, J L; Safarik, D J; Byler, D D; McClellan, K J; Uberuaga, B P; Scott, B L; Andersson, D A

2014-01-01

5

Uranium  

SciTech Connect

The two important oxidation states for uranium in natural environments are 4+ and 6+. Compounds containing quadrivalent uranium are insoluble in mildly acidic to alkaline conditions; whereas, those containing the linearly uranyl moiety (O=U=O)2+, are highly soluble and mobile. In solution, UO22+ forms soluble complexes with carbonate, oxalate, and hydroxide; UO22+ is also highly susceptible to adsorption either by organic matter, Fe oxyhydroxides, or precipitation with various anions, such as silicate, vanadate, arsenate, and phosphate. In ground water systems U(VI) is reduced to U(IV) if an effective reductant is present, such as H2S. Other reducing agents may be fossil plants, methane, and transported humic material. Uranium minerals display an extraordinary range structural and chemical variability, resulting from the different chemical conditions under which U minerals are formed.

Grenthe, Ingmar; Buck, Edgar C.; Drozdynski, J.; Fujino, T.; Albrecht-Schmitt, Thomas; Wolf, Steven F.

2006-07-31

6

First-principles calculations of uranium diffusion in uranium dioxide  

NASA Astrophysics Data System (ADS)

The present work reports first-principles DFT +U calculations of uranium self-diffusion in uranium dioxide (UO2), with a focus on comparing calculated activation energies to those determined from experiments. To calculate activation energies, we initially formulate a point defect model for UO2x that is valid for small deviations from stoichiometry. We investigate five migration mechanisms and calculate the corresponding migration barriers using both the LDA +U and GGA +U approximations. These energy barriers are calculated using the occupation matrix control scheme that allows one to avoid the metastable states that exist in the DFT +U approximation. The lowest migration barrier is obtained for a vacancy mechanism along the <110> direction. This mechanism involves significant contribution from the oxygen sublattice, with several oxygen atoms being displaced from their original position. The <110> vacancy diffusion mechanism is predicted to have lower activation energy than any of the interstitial mechanisms and comparison to experimental data for stoichiometric UO2 also confirms this mechanism.

Dorado, Boris; Andersson, David A.; Stanek, Christopher R.; Bertolus, Marjorie; Uberuaga, Blas P.; Martin, Guillaume; Freyss, Michel; Garcia, Philippe

2012-07-01

7

Design of a Uranium Dioxide Spheroidization System  

NASA Technical Reports Server (NTRS)

The plasma spheroidization system (PSS) is the first process in the development of tungsten-uranium dioxide (W-UO2) fuel cermets. The PSS process improves particle spherocity and surface morphology for coating by chemical vapor deposition (CVD) process. Angular fully dense particles melt in an argon-hydrogen plasma jet at between 32-36 kW, and become spherical due to surface tension. Surrogate CeO2 powder was used in place of UO2 for system and process parameter development. Particles range in size from 100 - 50 microns in diameter. Student s t-test and hypothesis testing of two proportions statistical methods were applied to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders show great than 800% increase in the number of spherical particles over the stock powder with the mean spherocity only mildly improved. It is recommended that powders be processed two-three times in order to reach the desired spherocity, and that process parameters be optimized for a more narrow particles size range. Keywords: spherocity, spheroidization, plasma, uranium-dioxide, cermet, nuclear, propulsion

Cavender, Daniel P.; Mireles, Omar R.; Frendi, Abdelkader

2013-01-01

8

Helium Migration Mechanisms in Polycrystalline Uranium Dioxide  

SciTech Connect

This study aims at identifying the release mechanisms of helium in uranium dioxide. Two sets of polycrystalline UO{sub 2} sintered samples presenting different microstructures were implanted with {sup 3}He ions at concentrations in the region of 0.1 at.%. Changes in helium concentrations were monitored using two Nuclear Reaction Analysis (NRA) techniques based on the {sup 3}He(d,{alpha}){sup 1}H reaction. {sup 3}He release is measured in-situ during sample annealing at temperatures ranging between 700 deg. C and 1000 deg. C. Accurate helium depth profiles are generated after each annealing stage. Results that provide data for further understanding helium release mechanisms are discussed. It is found that helium diffusion appears to be enhanced above 900 deg. C in the vicinity of grain boundaries possibly as a result of the presence of defects. (authors)

Martin, Guillaume; Desgardin, Pierre; Sauvage, Thierry; Barthe, Marie-France [CERI, CNRS, 3 A rue de la Ferollerie, ORLEANS, 45071 (France); Garcia, Philippe; Carlot, Gaelle [DEN/DEC/SESC/LLCC, CEA Cadarache, Saint Paul Lez Durance, 13108 (France)

2007-07-01

9

SULPHUR DIOXIDE LEACHING OF URANIUM CONTAINING MATERIAL  

Microsoft Academic Search

A process is described for extracting uranlum from uranium containing ; material, such as a low grade pitchblende ore, or mill taillngs, where at least ; part of the uraniunn is in the +4 oxidation state. After comminuting and ; magnetically removing any entrained lron particles the general material is made ; up as an aqueous slurry containing added ferric

A. Thunaes; F. T. Rabbits; K. D. Hester; H. W. Smith

1958-01-01

10

Oxygen diffusion in hypostoichiometric uranium dioxide  

SciTech Connect

The tracer oxygen diffusivity in UO/sub 2-x/ has been measured along the lower two phase boundary. The diffusion couple consisted of two matched hypostoichiometric uranium dioxide wafers, one enriched with /sup 18/O and the other normal. Results showed much higher diffusion coefficients than those of stoichiometric UO/sub 2/. This directly proved that the major defect species in UO/sub 2-x/ is the anion vacancy. Activation energy of anion vacancy migration was measured to be 11.7 +- 3.0 kcal/mole. A diffusion model established for UO/sub 2/ and UO/sub 2+-x/ showed that in stoichiometric UO/sub 2/ both interstitials and vacancies contribute significantly to oxygen diffusion and neither can be neglected; at 1400/sup 0/C their contributions are about equal. This model was extended to nearly stoichiometric UO/sub 2+-x/ to predict oxygen diffusion coefficients in these stoichiometry ranges. Also deduced from the model were the Frenkel defect energy and entropy of 85.6 +- 9.2 kcal/mole and 18.2 +- 7.3 eu, respectively. The contribution of Frenkel disorder to the excess enthalpy of UO/sub 2/ was evaluated. Calculation showed that Frenkel disorder accounts for 87% of the excess enthalpy at 3000/sup 0/K. A simple two band model for electronic excitation, with a band gap of 2.0 ev and effective electron mass of 7.6 m/sub e/, accounted for the remainder of the excess enthalpy.

Kim, K.C.

1980-12-01

11

Mixed uranium dicarbide and uranium dioxide microspheres and process of making same  

DOEpatents

Nuclear fuel microspheres are made by sintering microspheres containing uranium dioxide and uncombined carbon in a 1 mole percent carbon monoxide/99 mole percent argon atmosphere at 1550.degree. C. and then sintering the microspheres in a 3 mole percent carbon monoxide/97 mole percent argon atmosphere at the same temperature.

Stinton, David P. (Knoxville, TN)

1983-01-01

12

THE THERMAL CONDUCTANCE OF URANIUM DIOXIDE\\/STAINLESS STEEL INTERFACES  

Microsoft Academic Search

The thermal conductance of uranium dioxide\\/stainless steel interfaces ; was investigated in a disc-type apparatus under vacuum and with different ; interface gases (helium, argon, neon), and ranges of surface roughness (STA11 to ; 1417! x 10⁻⁶ cm, arithmetical mean height measured from Talysurf profile ; records), interface gas pressure (7 to 1226 mm Hg), contact pressure (0 to 570

A. C. Rapier; T. M. Jones; J. E. McIntosh

1963-01-01

13

Calculation Method for Gas Release from Uranium Dioxide Compacts.  

National Technical Information Service (NTIS)

Described is the method for calculation of gas release from the compacted uranium dioxide. The method is based on the gas atomic diffusion in the fuel. With this method in use the code GRETA has been developed intended for calculation of temperatures and ...

V. S. Sulaberidze A. V. Pershin

1983-01-01

14

Kinetic Study of the Carboreduction of Uranium Dioxide.  

National Technical Information Service (NTIS)

The reduction by graphite, in a carbon monoxide atmosphere, of uranium dioxide, UO sub 2 + 4C reversible UC sub 2 + 2CO has been studied thermogravimetrically in a pressure range of 60 to 510 torr from 1709 to 1818 exp 0 C. The kinetic law is parabolic; s...

G. Danger J. Besson

1974-01-01

15

Diffusion model of the non-stoichiometric uranium dioxide  

NASA Astrophysics Data System (ADS)

Uranium dioxide (UO2), which is used in light water reactors, exhibits a large range of non-stoichiometry over a wide temperature scale up to 2000 K. Understanding diffusion behavior of uranium oxides under such conditions is essential to ensure safe reactor operation. The current understanding of diffusion properties is largely limited by the stoichiometric deviations inherent to the fuel. The present DICTRA-based model considers diffusion across non-stoichiometric ranges described by experimentally available data. A vacancy and interstitial model of diffusion is applied to the U-O system as a function of its defect structure derived from CALPHAD-type thermodynamic descriptions. Oxygen and uranium self and tracer diffusion coefficients are assessed for the construction of a mobility database. Chemical diffusion coefficients of oxygen are derived with respect to the Darken relation and migration energies of defects are evaluated as a function of stoichiometric deviation.

Moore, Emily; Guneau, Christine; Crocombette, Jean-Paul

2013-07-01

16

Alternative Anodes for the Electrolytic Reduction of Uranium Dioxide  

NASA Astrophysics Data System (ADS)

Reprocessing of spent nuclear fuel is an essential step in closing the nuclear fuel cycle. In order to consume current stockpiles, ceramic uranium dioxide spent nuclear fuel will be subjected to an electrolytic reduction process. The current reduction process employs a platinum anode and a stainless steel alloy 316 cathode in a molten salt bath consisting of LiCl-2wt% Li 2O and occurs at 700C. A major shortcoming of the existing process is the degradation of the platinum anode under the severely oxidizing conditions encountered during electrolytic reduction. This work investigates alternative anode materials for the electrolytic reduction of uranium oxide. The high temperature and extreme oxidizing conditions encountered in these studies necessitated a unique set of design constraints on the system. Thus, a customized experimental apparatus was designed and constructed. The electrochemical experiments were performed in an electrochemical reactor placed inside a furnace. This entire setup was housed inside a glove box, in order to maintain an inert atmosphere. This study investigates alternative anode materials through accelerated corrosion testing. Surface morphology was studied using scanning electron microscopy. Surface chemistry was characterized using energy dispersive spectroscopy and Raman spectroscopy. Electrochemical behavior of candidate materials was evaluated using potentiodynamic polarization characteristics. After narrowing the number of candidate electrode materials, ferrous stainless steel alloy 316, nickel based Inconel 718 and elemental tungsten were chosen for further investigation. Of these materials only tungsten was found to be sufficiently stable at the anodic potential required for electrolysis of uranium dioxide in molten salt. The tungsten anode and stainless steel alloy 316 cathode electrode system was studied at the required reduction potential for UO2 with varying lithium oxide concentrations. Electrochemical impedance spectroscopy showed mixed (kinetic and diffusion) control and an overall low impedance due to extreme corrosion. It was observed that tungsten is sufficiently stable in LiCl - 2wt% Li 2O at 700C at the required anodic potential for the reduction of uranium oxide. This study identifies tungsten to be a superior anode material to platinum for the electrolytic reduction of uranium oxide, both in terms of superior corrosion behavior and reduced cost, and thus recommends that tungsten be further investigated as an alternative anode for the electrolytic reduction of uranium dioxide.

Merwin, Augustus

17

PRESSURE BONDING OF ZIRCALOY-CLAD FLAT-PLATE URANIUM-DIOXIDE FUEL ELEMENTS  

Microsoft Academic Search

A solid-state bonding technique involving the use of gas pressure at ; elevated temperatures is being investigated for the preparation of Zircaloy-clad ; flat-plate uranium dioxide fuel elements. In this procedure, the fuel-element ; components, consisting of a compartmented Zircaloy picture frame, uranium dioxide ; fuel plates, and Zircaloy caldding plates, are assembled into a container that is ; evacuated

S. J. Paprocki; E. S. Hodge; D. C. Carmichael

1958-01-01

18

The adsorption of methyl iodide on uranium and uranium dioxide: Surface characterization using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES)  

NASA Astrophysics Data System (ADS)

The adsorption of methyl iodide on uranium and on uranium dioxide has been studied at 25 C. Surfaces of the substrates were characterized before and after adsorption by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The XPS binding energy results indicate that CH 3I adsorption on uranium yields a carbide-type carbon, UC, and uranium iodide, UI 3. On uranium dioxide the carbon electron binding energy measurements are consistent with the formation of a hydrocarbon, CH 3-type moiety. The interpretation of XPS and AES spectral features for CH 3I adsorption on uranium suggest that a complex dissociative adsorption reaction takes place. Adsorption of CH 3I on UO 2 occurs via a dissociative process. Saturation coverage occurs on uranium at approximately two langmuir (1 L = 10 -6 Torr s) exposure whereas saturation coverage on uranium dioxide is found at about five langmuir.

Dillard, J. G.; Moers, H.; Klewe-Nebenius, H.; Kirch, G.; Pfennig, G.; Ache, H. J.

1984-09-01

19

Pathway and energetics of xenon migration in uranium dioxide  

NASA Astrophysics Data System (ADS)

Using a combination of density functional theory (DFT), classical potentials, molecular dynamics, and nudged elastic band (NEB) calculations, we explore the diffusion of xenon in uranium dioxide (UO2). We compare migration barriers of empirical potentials with DFT by performing NEB calculations and subsequently we use the DFT-validated empirical potentials to calculate vacancy clusters, with and without xenon, to determine the migration path and barrier of xenon in bulk UO2. We find the following: (i) Two empirical potentials out of four tested agree qualitatively with DFT derived energetics for Schottky defect migration; (ii) through the use of molecular dynamics with empirical potentials, we have found a path for the diffusion of xenon-tetravacancy clusters (Xe+2VU+2VO); (iii) this path has an energy barrier significantly lower than previously reported paths by nearly 1 eV; (iv) we examine the physical contributions to the migration pathway and find the barrier is largely electrostatic and that xenon contributes very little to the barrier height; (v) once a uranium vacancy attaches to a xenon-Schottky defect, the resulting xenon-tetravacancy cluster is strongly bound; and (vi) as xenon in a tetravacancy, a xenon-double Schottky defect can diffuse in a concerted manor with a comparable barrier to xenon in a tetravacancy, but two of the oxygen vacancies are only weakly bound to the defect.

Thompson, Alexander E.; Wolverton, C.

2013-03-01

20

Irradiation of TZM: Uranium dioxide fuel pin at 1700 K  

NASA Technical Reports Server (NTRS)

A fuel pin clad with TZM and containing solid pellets of uranium dioxide was fission heated in a static helium-cooled capsule at a maximum surface temperature of 1700 K for approximately 1000 hr and to a total burnup of 2.0 percent of the uranium-235. The results of the postirradiation examination indicated: (1) A transverse, intergranular failure of the fuel pin occurred when the fuel pin reached 2.0-percent burnup. This corresponds to 1330 kW-hr/cu cm, where the volume is the sum of the fuel, clad, and void volumes in the fuel region. (2) The maximum swelling of the fuel pin was less than 1.5 percent on the fuel-pin diameter. (3) There was no visible interaction between the TZM clad and the UO2. (4) Irradiation at 1700 K produced a course-grained structure, with an average grain diameter of 0.02 centimeter and with some of the grains extending one-half of the thickness of the clad. (5) Below approximately 1500 K, the irradiation of the clad produced a moderately fine-grained structure, with an average grain diameter of 0.004 centimeter.

Mcdonald, G. E.

1973-01-01

21

Sorption behaviour of uranium and thorium on cryptomelane-type hydrous manganese dioxide from aqueous solution  

SciTech Connect

The kinetics of sorption of uranium and thorium from aqueous nitrate solutions on cryptomelane-type hydrous manganese dioxide (CRYMO) was studied. The exchange of uranium is particle diffusion controlled while that of thorium is chemical reaction at the exchange sites. Sorption of uranium and thorium by CRYMO has been also studied as a function of metal concentrations and temperature. The sorption of both cations is found to be an endothermic process and increases markedly with temperature between 30 and 60{degree}C. The sorption results have been analysed by the langmuir adsorption isotherm over the entire range of uranium and thorium concentrations investigated. 35 refs., 8 figs., 5 tabs.

El-Naggar, I.M.; El-Absy, M.A.; Abdel-Hamid, M.M.; Aly, H.F. [Atomic Authority, Cairo (Egypt)

1993-07-01

22

Boron nitride - boron hybrid coating on uranium dioxide-gadolinium oxide fuel. Final report for the period 1 November 1996 - 1 November 1997.  

National Technical Information Service (NTIS)

The report describes work to develop laboratory-scale technology of the deposition of hybrid boron nitrate-metallic boron coating onto the surface of uranium dioxide ore uranium dioxide - gadolinia dioxide fuel pellets. Methods of chemical vapour depositi...

G. Gunduz

1997-01-01

23

A thermal modelling of displacement cascades in uranium dioxide  

NASA Astrophysics Data System (ADS)

The space and time dependent temperature distribution was studied in uranium dioxide during displacement cascades simulated by classical molecular dynamics (MD). The energy for each simulated radiation event ranged between 0.2 keV and 20 keV in cells at initial temperatures of 700 K or 1400 K. Spheres into which atomic velocities were rescaled (thermal spikes) have also been simulated by MD to simulate the thermal excitation induced by displacement cascades. Equipartition of energy was shown to occur in displacement cascades, half of the kinetic energy of the primary knock-on atom being converted after a few tenths of picoseconds into potential energy. The kinetic and potential parts of the system energy are however subjected to little variations during dedicated thermal spike simulations. This is probably due to the velocity rescaling process, which impacts a large number of atoms in this case and would drive the system away from a dynamical equilibrium. This result makes questionable MD simulations of thermal spikes carried out up to now (early 2014). The thermal history of cascades was compared to the heat equation solution of a punctual thermal excitation in UO2. The maximum volume brought to a temperature above the melting temperature during the simulated cascade events is well reproduced by this simple model. This volume eventually constitutes a relevant estimate of the volume affected by a displacement cascade in UO2. This definition of the cascade volume could also make sense in other materials, like iron.

Martin, G.; Garcia, P.; Sabathier, C.; Devynck, F.; Krack, M.; Maillard, S.

2014-05-01

24

Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis  

SciTech Connect

The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

Nelson, Andrew T. [Los Alamos National Laboratory

2012-08-30

25

Penetrate-leach dissolution of zirconium-clad uranium and uranium dioxide fuels  

Microsoft Academic Search

A new decladding-dissolution process was developed for zirconium-clad uranium metal and UO fuels. The proposed penetrate-leach process consists of penetrating the zirconium cladding with Alniflex solution (2M HF--1M HNO--1M Al(NO)--0.1M KCrO) and of leaching the exposed core with 10M HNO. Undissolved cladding pieces are discarded as solid waste. Periodic HF and HNO additions, efficient agitation, and in-line zirconium analyses are

1975-01-01

26

Process for continuous production of metallic uranium and uranium alloys  

DOEpatents

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

Hayden, Jr., Howard W. (Oakridge, TN); Horton, James A. (Livermore, CA); Elliott, Guy R. B. (Los Alamos, NM)

1995-01-01

27

Process for continuous production of metallic uranium and uranium alloys  

DOEpatents

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

1995-06-06

28

Simulation of uranium dioxide polymorphs and their phase transitions  

NASA Astrophysics Data System (ADS)

In this article first-principles DFT calculations and molecular dynamics simulations using empirical potentials have been used to study four different polymorphs of uranium dioxide that appear under high compressive and tensile deformations. It has been found, as expected, that the ground-state structure is the fluorite-type structure (space group Fm3m). Under high compressive deformation urania transforms into cotunnite-type structure (space group Pnma), as already known experimentally. The calculated transition pressure is 28 GPa in agreement with the experimental data. Under tensile deformation urania transforms into either scrutinyite-type structure (space group Pbcn) or rutile-type (space group P42/mnm) structure. These two phases are almost energetically degenerate; hence it is impossible to distinguish which phase is the most favorable. The transition pressure for both phases is found to be equal to -10 GPa. Subsequently, assessment of four of the most used empirical potentials for UO2Morelon, Arima, Basak, and Yakubhave been carried out comparing the equations of state with those found with DFT calculations. The Morelon potential has been found to be the most accurate to describe the different urania polymorphs. Using this empirical potential and a dedicated minimization procedure, complete transition pathways between the ground state (Fm3m) and both tensile structures (Pbcn or P42/mnm) are described. Finally, uniaxial tensile load molecular dynamics simulations have been performed. It has been found that for load in the <100> direction urania transforms into the Pbcn structure while for load in the <110> direction it transits towards the P42/mnm structure.

Fossati, Paul C. M.; Van Brutzel, Laurent; Chartier, Alain; Crocombette, Jean-Paul

2013-12-01

29

Determination of laser-evaporated uranium dioxide by neutron activation analysis  

SciTech Connect

Safety analyses of nuclear reactors require information about the loss of fuel which may occur at high temperatures. In this study, the surface of a uranium dioxide target was heated rapidly by a laser. The uranium surface was vaporized into a vacuum. The uranium bearing species condensed on a graphite disk placed in the pathway of the expanding uranium vapor. Scanning electron microscopy and X-ray analysis showed very little droplet ejection directly from the laser target surface. Neutron activation analysis was used to measure the amount of uranium deposited. The surface temperature was measured by a fast-response automatic optical pyrometer. The maximum surface temperature ranged from 2400 to 3700/sup 0/K. The Hertz-Langmuir formula, in conjunction with the measured surface temperature transient, was used to calculate the theoretical amount of uranium deposited. There was good agreement between theory and experiment above the melting point of 3120/sup 0/K. Below the melting point much more uranium was collected than was expected theoretically. This was attributed to oxidation of the surface. 29 refs., 16 figs., 7 tabs.

Allred, R.

1987-05-01

30

Depleted Uranium  

MedlinePLUS

... Military Sexual Trauma Radiation Chemical, Biological, and Radiological Weapons Cold Injury Hearing Impairment Visual Impairment Former Prisoners ... from natural uranium used in nuclear reactors or weapons leaves depleted uranium. DU has 40 percent less ...

31

Swelling and gas release of grain-boundary pores in uranium dioxide  

Microsoft Academic Search

The swelling and gas release of overpressured grain boundary pores is sintered unirradiated uranium dioxide were investigated under isothermal conditions. The pores became overpressured when the ambient pressure was reduced, and the excess pressure driving force caused growth and interconnection of the pores, leading to eventual gas release. Swelling was measured continuously by a linear variable differential transformer, and open

Schrire

1983-01-01

32

CALCULATION OF COHESIVE AND SURFACE ENERGIES OF THORIUM AND URANIUM DIOXIDES  

Microsoft Academic Search

S>The cohesive and surface energies of thorium and uranium dioxides were ; estimnted theoreticaily by computations based on a Born-Mayer type of model. The ; sensitivity of the results to changes in the data used for the calculations is ; illustrated and discussed. (auth);

G. C. Benson; P. I. Freeman; E. Dempsey

1963-01-01

33

Heterogeneous nucleation of fission gas bubbles and gas migration in uranium dioxide  

Microsoft Academic Search

The number and size of fission gas bubbles precipitated in irradiated uranium dioxide are calculated from a theory based on a balance between nucleation of bubbles at vacancy clusters produced by fission fragments and the agglomeration of bubbles by random motion. The distribution of bubble sizes is determined by gas atom capture, bubble agglomeration and irradiation re-solution. Irradiation re-solution exceeds

A. D. Whapham

1972-01-01

34

Enriched Uranium  

NSDL National Science Digital Library

This Wikipedia website provides information about the various concentrations of uranium used for different applications. Topics include a brief description of the grades of uranium and methods of isotope separation. There are also links to other aspects of uranium enrichment and related information. This information lays the foundation for informed discussion about the potential of nuclear energy and the risks of nuclear proliferation.

Wikipedia

35

Coating a uranium dioxide nuclear fuel with a zirconium diboride burnable poison  

SciTech Connect

This patent describes a nuclear reactor fuel assembly having a fuel rod containing a burnable poison coated nuclear fuel pellet. The fuel pellet consists of: (a) a generally cylindrical substrate consisting essentially of uranium dioxide; (b) a bondably deposited layer consisting essentially of niobium circumferentially surrounding the substrate; and (c) a bondably deposited burnable poison layer consisting essentially of zirconium diboride circumferentially surrounding the niobium layer.

Chubb, W.

1986-04-15

36

Low cost, proliferation resistant, uraniumthorium dioxide fuels for light water reactors  

Microsoft Academic Search

Our objective is to develop a fuel for the existing light water reactors (LWRs) that, (a) is less expensive to fabricate than the current uranium-dioxide (UO2) fuel; (b) allows longer refueling cycles and higher sustainable plant capacity factors; (c) is very resistant to nuclear weapon-material proliferation; (d) results in a more stable and insoluble waste form; and (e) generates less

J. Stephen Herring; Philip E MacDonald; Kevan D Weaver; Craig Kullberg

2001-01-01

37

THERMODYNAMIC MODEL FOR URANIUM DIOXIDE BASED NUCLEAR FUEL  

SciTech Connect

Many projects involving nuclear fuel rest on a quantitative understanding of the co-existing phases at various stages of burnup. Since the many fission products have considerably different abilities to chemically associate with oxygen, and the oxygen-to-metal molar ratio is slowly changing, the chemical potential of oxygen is a function of burnup. Concurrently, well-recognized small fractions of new phases such as inert gas, noble metals, zirconates, etc. also develop. To further complicate matters, the dominant UO2 fuel phase may be non-stoichiometric and most of the minor phases themselves have a variable composition dependent on temperature and possible contact with the coolant in the event of a sheathing breach. A thermodynamic fuel model to predict the phases in partially burned CANDU (CANada Deuterium Uranium) nuclear fuel containing many major fission products has been under development. The building blocks of the model are the standard Gibbs energies of formation of the many possible compounds expressed as a function of temperature. To these data are added mixing terms associated with the appearance of the component species in particular phases. In operational terms, the treatment rests on the ability to minimize the Gibbs energy in a multicomponent system, in our case using the algorithms developed by Eriksson. The model is capable of handling non-stoichiometry in the UO2 fluorite phase, dilute solution behaviour of significant solute oxides, noble metal inclusions, a second metal solid solution U(Pd-Rh-Ru)3, zirconate, molybdate, and uranate solutions as well as other minor solid phases, and volatile gaseous species.

Thompson, Dr. William T. [Royal Military College of Canada; Lewis, Dr. Brian J [Royal Military College of Canada; Corcoran, E. C. [Royal Military College of Canada; Kaye, Dr. Matthew H. [Royal Military College of Canada; White, S. J. [Royal Military College of Canada; Akbari, F. [Atomic Energy of Canada Limited, Chalk River Laboratories; Higgs, Jamie D. [Atomic Energy of Canada Limited, Point Lepreau; Thompson, D. M. [Praxair Inc.; Besmann, Theodore M [ORNL; Vogel, S. C. [Los Alamos National Laboratory (LANL)

2007-01-01

38

Production of small uranium dioxide microspheres for cermet nuclear fuel using the internal gelation process  

SciTech Connect

The U.S. National Aeronautics and Space Administration (NASA) is developing a uranium dioxide (UO2)/tungsten cermet fuel for potential use as the nuclear cryogenic propulsion stage (NCPS). The first generation NCPS is expected to be made from dense UO2 microspheres with diameters between 75 and 150 m. Previously, the internal gelation process and a hood-scale apparatus with a vibrating nozzle were used to form gel spheres, which became UO2 kernels with diameters between 350 and 850 m. For the NASA spheres, the vibrating nozzle was replaced with a custom designed, two-fluid nozzle to produce gel spheres in the desired smaller size range. This paper describes the operational methodology used to make 3 kg of uranium oxide microspheres.

Collins, Robert T [ORNL] [ORNL; Collins, Jack Lee [ORNL] [ORNL; Hunt, Rodney Dale [ORNL] [ORNL; Ladd-Lively, Jennifer L [ORNL] [ORNL; Patton, Kaara K [ORNL] [ORNL; Hickman, Robert [NASA Marshall Space Flight Center, Huntsville, AL] [NASA Marshall Space Flight Center, Huntsville, AL

2014-01-01

39

Studies on Production of Sinterable Uranium Dioxide in a Small-Scale Batch Process Using Uranyl Nitrate Solution, Ammonum Polyuranate--Uranium Dioxide Method.  

National Technical Information Service (NTIS)

Slow precipitation from aqueous solutions of uranium nitrate with a concentration of about 60 to 65 g uranium per liter, using aqueous solutions of ammonia with a concentration of about 7 to 7.5 mol/liter, and at 60 exp 0 C, are good conditions for produc...

R. Wlodarski W. Dembinski R. Przytycka Z. Nowakowska

1978-01-01

40

Uranium Reduction  

SciTech Connect

The dramatic decrease in solubility accompanying thereduction of U(VI) to U(IV), producing the insoluble mineral uraninite,has been viewed as a potential mechanism for sequestration of environmentaluranium contamination. In the past 15 years, it has been firmlyestablished that a variety of bacteria exhibit this reductive capacity.To obtain an understanding of the microbial metal metabolism, to developa practical approach for the acceleration of in situ bioreduction, and topredict the long-term fate of environmental uranium, several aspects ofthe microbial process have been experimentally explored. This reviewbriefly addresses the research to identify specific uranium reductasesand their cellular location, competition between uranium and otherelectron acceptors, attempts to stimulate in situ reduction, andmechanisms of reoxidation of reduced uranium minerals.

Wall, J.D.; Krumholz, L.R.

2007-04-02

41

Uranium industry annual 1994.  

National Technical Information Service (NTIS)

The Uranium Industry Annual 1994 (UIA 1994) provides current statistical data on the US uranium industry's activities relating to uranium raw materials and uranium marketing during that survey year. The UIA 1994 is prepared for use by the Congress, Federa...

1995-01-01

42

Migration of defect clusters and xenon-vacancy clusters in uranium dioxide  

NASA Astrophysics Data System (ADS)

The possible transition states, minimum energy paths (MEPs) and migration mechanisms of defect clusters and xenon-vacancy defect clusters in uranium dioxide (UO2) have been investigated using the dimer and the nudged elastic-band (NEB) methods. The nearby O atom can easily hop into the oxygen vacancy position by overcoming a small energy barrier, which is much lower than that for the migration of a uranium vacancy. A simulation for a vacancy cluster consisting of two oxygen vacancies reveals that the energy barrier of the divacancy migration tends to decrease with increasing the separation distance of divacancy. For an oxygen interstitial, the migration barrier for the hopping mechanism is almost three times larger than that for the exchange mechanism. Xe moving between two interstitial sites is unlikely a dominant migration mechanism considering the higher energy barrier. A net migration process of a Xe-vacancy pair containing an oxygen vacancy and a xenon interstitial is identified by the NEB method. We expect the oxygen vacancy-assisted migration mechanism to possibly lead to a long distance migration of the Xe interstitials in UO2. The migration of defect clusters involving Xe substitution indicates that Xe atom migrating away from the uranium vacancy site is difficult.

Chen, Dong; Gao, Fei; Deng, Hui-Qiu; Liu, Bo; Hu, Wang-Yu; Sun, Xin

2014-04-01

43

Repository Criticality Control with Depleted-Uranium-Dioxide Cermet Waste Packages  

SciTech Connect

It is proposed that the structural components and internal basket structures of waste packages (WPs) be constructed of depleted uranium dioxide (DUO{sub 2})-steel cermets. The cermet contains 2 DUO{sub 2} imbedded in a steel matrix. The WPs are filled with spent nuclear fuel (SNF) and placed 2 in a geological repository. The WP provides a handling container for placement of SNF in the repository and is an engineered barrier to delay SNF degradation and subsequent release of radionuclides. SNF and other fissile wastes contain enriched uranium and transuranic fissile isotopes; thus, the potential for nuclear criticality exists. Most of the transuranic fissile isotopes, such as {sup 239}Pu, will have decayed to {sup 233}U or {sup 235}U before significant fissile-isotope migration from the degraded SNF or other fissile waste forms has occurred. Consequently, post-closure repository criticality issues are primarily from the fissile isotopes of uranium. As the WP degrades, the {sup 238}U in the DUO{sub 2}-steel cermet would mix with the degrading SNF and isotopically dilute {sup 233}U and {sup 235}U to levels that would ensure that post-closure criticality would not occur.

Forsberg, C.W.

2001-07-12

44

X-ray photoelectron studies of thorium, uranium, and their dioxides  

NASA Astrophysics Data System (ADS)

The valence-band structures of the light actinides thorium, uranium, and their dioxides have been investigated by means of x-ray photoemission spectroscopy. This study shows that the electronic structures of ThO2 and UO2 are quite similar, except for the presence of 5f electrons in UO2 which lie close to the Fermi level. It is these low-binding-energy 5f electrons that give rise to the most dramatic differences in physical properties, notably the magnetism, electrical conductivity, and color. Conduction in UO2 apparently occurs via holes created by excitation of rather localized 5f electrons from the uranium to interstitial oxygen-acceptor sites. Sputtering experiments on thin oxide film and bulk samples show Fermi-level shifts in x-ray photoemission spectra associated with doping changes that result from preferential removal of interstitial ("impurity") oxygen atoms. The deep-trap and polaron conduction models have been reexamined. It is our view, at this time, that neither model can be ruled out. For the pure metal thorium, valence-band spectra were compared with the available density-of-states calculations and satisfactory agreement was obtained. For ?-uranium, no detailed band calculation exists. However, the results agree with the qualitative density-of-states picture presented by Friedel.

Veal, B. W.; Lam, D. J.

1974-12-01

45

Contribution a l'etude du role de dopants dans la densification et la croissance cristalline du dioxyde d'uranium. (Effect of additives on enhanced sintering and grain growth in uranium dioxide).  

National Technical Information Service (NTIS)

The use of sintering additives has been the most effective way of promoting grain growth of uranium dioxide. We have established a same mechanism for additives which belongs to corundum structure: chromium, aluminium, vanadium and titanium sesquioxides. S...

L. Bourgeois

1992-01-01

46

A classical molecular dynamics study of the correlation between the Bredig transition and thermal conductivity of stoichiometric uranium dioxide  

Microsoft Academic Search

Thermophysical properties of uranium dioxide are investigated by classical molecular dynamics for temperatures from 300K to 3000K. An increase of specific heat in the temperature range from 1300K to 2500K is noted. Comparison with a theoretical model shows that the origin of this behavior is only due to anharmonicity. Such characteristic features of the Bredig transition as the peak in

Artem V. Lunev; Boris A. Tarasov

2011-01-01

47

Characteristics of a Mixed Thorium - Uranium Dioxide High-Burnup Fuel  

SciTech Connect

Future nuclear fuel must satisfy three sets of requirements: longer times between refueling; concerns for weapons proliferation; and development of a spent fuel form more suitable for direct geologic disposal. This project has investigated a fuel consisting of mixed thorium and uranium dioxide to satisfy these requirements. Results using the SCALE 4.3 code system indicated that the mixed Th-U fuel could be burned to 72 MWD/kg or 100 MWD/kg using 25% and 35% UO2 respectively. The uranium remained below 20 % total fissile fraction throughout the cycle, making it unusable for weapons. Total plutonium production per MWD was a factor of 4.5 less in the Th-U fuel than in the conventional fuel; Pu-239 production per MWD was a factor of 6.5 less; and the plutonium produced was high in Pu-238, leading to a decay heat 5 times greater than that from plutonium derived from conventional fuel and 40 times greater than weapons grade plutonium. High decay heat would require active cooling of any crude weapon, lest the components surrounding the plutonium be melted. Spontaneous neutron production for plutonium from Th-U fuel was 2.3 times greater than that from conventional fuel and 15 times greater than that from weapons grade plutonium. High spontaneous neutron production drastically limits the probable yield of a crude weapon. Because ThO2 is the highest oxide of thorium, while UO2 can be oxidized further to U3O8, ThO2- UO2 fuel may be a superior wasteform if the spent fuel is ever to be exposed to oxygenated water. Even if the cost of fabricating the mixed Th-U fuel is $100/kg greater, the cost of the Th-U fuel is 13% to 25% less than that of the fuels using uranium only.

Herring, James Stephen; Mac Donald, Philip Elsworth

1999-06-01

48

Characteristics of a Mixed Thorium-Uranium Dioxide High-Burnup Fuel  

SciTech Connect

Future nuclear fuels must satisfy three sets of requirements: longer times between refueling; concerns for weapons proliferation; and development of a spent fuel form more suitable for direct geologic disposal. This project has investigated a fuel consisting of mixed thorium and uranium dioxide to satisfy these requirements. Results using the SCALE 4.3 code system indicated that the mixed Th-U fuel could be burned to 72 MWD/kg or 100 MWD/kg using 25% of 35% UO2 respectively. The uranium remained below 20% total fissile fraction throughout the cycle, making it unusable for weapons. Total plutonium production per MWD was a factor of 4.5 less in the Th-U fuel than in the conventional fuel; Pu-239 production per MWD was a factor of 6.5 less; and the plutonium produced was high in Pu-238, leading to a decay heat 5 times greater than that from plutonium derived from conventional fuel and 40 times greater than weapons grade plutonium. High decay heat would require active cooling of any crude weapon, lest the components surrounding the plutonium be melted. Spontaneous neutron production for plutonium from Th-U fuel was 2.3 times greater than that from conventional fuel and 15 times greater than that from weapons grade plutonium. High spontaneous neutron production drastically limits the probable yield of a crude weapon. Because ThO2 is the highest oxide of thorium, while UO2 can be oxidized further to U3O8, ThO2-UO2 fuel may be a superior wasteform if the spent fuel is ever to be exposed to oxygenated water. Even if the cost of fabricating the mixed Th-U fuel is $100/kg greater, the cost of the Th-U fuel is 13% to 15% less than that of the fuels using uranium only.

J. S. Herring; P. E. MacDonald

1999-06-01

49

Studies on the dissolution kinetics of ceramic uranium dioxide particles in nitric acid by microwave heating  

NASA Astrophysics Data System (ADS)

The kinetics of dissolution of uranium dioxide particles in 4-8 M (M = mol/L) nitric acid by microwave heating has been studied. It is supposed that the UO 2 particles dissolve homogeneously in the form of spherical particles. The dissolution process can be dealt with the well-known shrinking core model. The results show that under the 600 W microwave field, the dissolution of UO 2 particles is controlled by the product layer diffusion at the temperature of 90-110 C. The average activation energy for the dissolution of UO 2 particles in 4-8 M nitric acid was calculated to be 73.2 1.8 kJ/mol from Arrhenius plots.

Zhao, Yunfeng; Chen, Jing

2008-02-01

50

Uranium Industry Annual, 1992  

SciTech Connect

The Uranium Industry Annual provides current statistical data on the US uranium industry for the Congress, Federal and State agencies, the uranium and electric utility industries, and the public. The feature article, ``Decommissioning of US Conventional Uranium Production Centers,`` is included. Data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2.

Not Available

1993-10-28

51

Reaction Model for Fluorination of Uranium Dioxide Using Improved Unreacted Shrinking Core Model for Expanding Spherical Particles  

Microsoft Academic Search

A gas-solid reaction model is developed to represent the fluorination of uranium dioxide (UO2), which consists of a two-step reaction: the formation of a solid intermediate of uranyl fluoride (UO2F2) on thecore of unreacted UO2 and the consumption of UO2F2. The model is an extension of the unreacted shrinking core model with a shrinking spherical particle and takes into account

Shunji HOMMA; Yuki UOI; Artur BRAUN; Jiro KOGA; Shiro MATSUMOTO

2008-01-01

52

Photochemistry of uranium compounds  

SciTech Connect

This paper reviews the unclassified progress on the photochemistry of the following uranium compounds: UF/sub 6/, othe uranium halides, classical coordination complexes, uranium alkoxides, organometallic compounds, and uranium borohydride. Uranyl compounds are mentioned briefly. Recommendations for future studies are given. 61 references. (DLC)

Paine, R.T.; Kite, M.S.

1980-01-01

53

Uranium Industry Annual 1999.  

National Technical Information Service (NTIS)

The Uranium Industry Annual 1999 (UIA 1999) provides current statistical data on the U.S. uranium industry's activities relating to uranium raw materials and uranium marketing. The UIA 1999 is prepared for use by the Congress, Federal and State agencies, ...

2000-01-01

54

Etching of uranium dioxide in nitrogen trifluoride RF plasma glow discharge  

NASA Astrophysics Data System (ADS)

A series of room temperature, low pressure (10.8 to 40 Pa), low power (25 to 210 W) RF plasma glow discharge experiments with UO2 were conducted to demonstrate that plasma treatment is a viable method for decontaminating UO2 from stainless steel substrates. Experiments were conducted using NF3 gas to decontaminate depleted uranium dioxide from stainless-steel substrates. Results demonstrated that UO2 can be completely removed from stainless-steel substrates after several minutes processing at under 200 W. At 180 W and 32.7 Pa gas pressure, over 99% of all UO2 in the samples was removed in just 17 minutes. The initial etch rate in the experiments ranged from 0.2 to 7.4 mum/min. Etching increased with the plasma absorbed power and feed gas pressure in the range of 10.8 to 40 Pa. A different pressure effect on UO2 etching was also noted below 50 W in which etching increased up to a maximum pressure, 23 Pa, then decreased with further increases in pressure. A computer simulation, CHEMKIN, was applied to predict the NF3 plasma species in the experiments. The code was validated first by comparing its predictions of the NF3 plasma species with mass spectroscopy etching experiments of silicon. The code predictions were within +/-5% of the measured species concentrations. The F atom radicals were identified as the primary etchant species, diffusing from the bulk plasma to the UO2 surface and reacting to form a volatile UF6, which desorbed into the gas phase to be pumped away. Ions created in the plasma were too low in concentration to have a major effect on etching, but can enhance the etch rate by removing non-volatile reaction products blocking the reaction of F with UO2. The composition of these non-volatile products were determined based on thermodynamic analysis and the electronic structure of uranium. Analysis identified possible non-volatile products as the uranium fluorides, UF2-5, and certain uranium oxyfluorides UO2F, UO2F2, UOF3, and UOF 4 which form over the UO2 surface. Successive reactions between these products and F atoms lead to the formation of UF6. The UF 6 has a vapor pressure of 24 kPa, well above the operating pressure at the gas temperature (300 K) of the plasma, and, as a consequence, desorbs into the gas phase. The other Intermediate fluorides and oxyfluorides are solids and remain on the surface, eventually slowing or blocking the etch reaction as they accumulate. These results explain why when power was too low, the etch reactions completely stopped before all detectable UO2 could be fully etched. Comparison of UO2 with previously measured PuO2 etch rates showed that the removal of UO2 and PuO2were comparable and differences could be accounted for by differences in experimental conditions. The chemistry and reaction thermodynamics of UO2 have many parallels to those of PuO2, such as similar vapor pressures at room temperature (24 vs. 14 kPa) and favorable Gibbs free energy of formation of many species. (Abstract shortened by UMI.)

Veilleux, John Mark

1999-10-01

55

Separation and mass spectrometry of nanogram quantities of uranium and thorium from thorium-uranium dioxide fuels  

SciTech Connect

A microchemical procedure was developed for the separation and isotopic analysis of U and Th from irradiated (Th,U)O/sub 2/ fuel. The separation procedure consisted of two stages; in the first a tributyl phosphate impregnated resin bead was equilibrated with the dissolved fuel in 0.08 M HF/6 M HNO/sub 3/ solution. The bead sorbed approximately 1.7 ..mu..g of U and 4.8..mu..g of Th and provided good separation of these from the fission products. In the second stage, the U and Th were back-extracted into 0.025 M HF/8 M HNO/sub 3/ solution, which contained a small anion-exchange membrane disk. The disk adsorbed approximately 14 ng of U and 45 ng of Th, and subsequently was transferred to the ionizing filament of a thermal-ionization mass spectrometer and covered with a starch deposit. Sensitivities were sufficiently high for sequential analysis of these quantities of Th and U from a single disk. Isotopic data obtained for a combined U and Th standard showed excellent agreement with certified values: overall bias and precision were < 0.03% and 0.2% relative standard deviation, respectively, for both elements. The applicability of the procedure to uranium fuels was also demonstrated. 6 figures, 2 tables.

Green, L.W.; Elliot, N.L.; Longhurst, T.H.

1983-12-01

56

The diffusion coefficients of gaseous and volatile species during the irradiation of uranium dioxide  

NASA Astrophysics Data System (ADS)

Measurements of release for rare gas fission products from single and polycrystalline uranium dioxide during irradiation are described. The fuel samples were enriched to 20% in 235U to avoid uncertainties in the fission rate due to plutonium production. The surface area of the single crystals was determined optically to provide a reference of known surface-to-volume ratio for the determination of diffusion coefficients for the rare gases and their halogen precursors. The initial part of the experiment was isothermal, during which the time dependence of release was observed and the polycrystalline material developed extensively interlinked grain-boundary porosity. Subsequently the temperature dependence of the release process was studied. It is concluded that the diffusion of rare gas atoms in UO 2 during irradiation is a complex process involving more than one rate-controlling mechanism and bears a close similarity to cation self-diffusion. In both cases, the low-temperature kinetics are radically affected by irradiation damage. The present results are well represented by a composite diffusion coefficient containing three terms one representing high-temperature intrinsic behaviour whilst the other two represent the effect of irradiation enhancement. This equation should be modified to take account of intragranular bubbles at all temperatures for stable gas release, and at high temperatures in the case of unstable species.

Turnbull, J. A.; Friskney, C. A.; Findlay, J. R.; Johnson, F. A.; Walter, A. J.

1982-06-01

57

Derivation of enhanced potentials for uranium dioxide and the calculation of lattice and intrinsic defect properties  

NASA Astrophysics Data System (ADS)

Previously reported forms of the cation-anion Buckingham potential provide a significantly greater contribution than the repulsive Coulombic component at short-range thus predicting an unphysical attraction between the pair of ions. A detailed reappraisal of the computer modelling of uranium dioxide (UO 2) employing atomistic simulation techniques is presented. An improved set of interatomic potentials is derived in order to describe the lattice correctly under conditions subsequent to radiation damage with the creation of Frenkel pair defects. Novel methodology is employed in the derivation of potentials ensuring applicability over the entire region of interest. The cation-anion potential is obtained via a combination of empirical fitting to crystal structural data and parametric fitting to additional physical properties. These potentials are subsequently verified and validated by calculation of additional bulk lattice properties, whose values agree favourably with those measured experimentally. Atomistic computer simulation techniques are then used to investigate the defect properties of UO 2. The theoretical techniques are based upon efficient energy minimization procedures and Mott-Littleton methodology for accurate defect modelling and employed to calculate intrinsic defect formation energies and enable predictions of the expected type of intrinsic disorder to be made.

Read, Mark S. D.; Jackson, Robert A.

2010-11-01

58

Results of Uranium Dioxide-Tungsten Irradiation Test and Post-Test Examination  

NASA Technical Reports Server (NTRS)

A uranium dioxide (UO2) fueled capsule was fabricated and irradiated in the NASA Plum Brook Reactor Facility. The capsule consisted of two bulk UO2 specimens clad with chemically vapor deposited tungsten (CVD W) 0.762 and 0.1016 cm (0.030-and 0.040-in.) thick, respectively. The second specimen with 0.1016-cm (0.040-in.) thick cladding was irradiated at temperature for 2607 hours, corresponding to an average burnup of 1.516 x 10 to the 20th power fissions/cu cm. Postirradiation examination showed distortion in the bottom end cap, failure of the weld joint, and fracture of the central vent tube. Diametral growth was 1.3 percent. No evidence of gross interaction between CVD tungsten or arc-cast tungsten cladding and the UO2 fuel was observed. Some of the fission gases passed from the fuel cavity to the gas surrounding the fuel specimen via the vent tube and possibly the end-cap weld failure. Whether the UO2 loss rates through the vent tube were within acceptable limits could not be determined in view of the end-cap weld failure.

Collins, J. F.; Debogdan, C. E.; Diianni, D. C.

1973-01-01

59

Design of a uranium-dioxide powder spheroidization system by plasma processing  

NASA Astrophysics Data System (ADS)

The plasma spheroidization system (PSS) is the first process in the development of a tungsten-uranium dioxide (W-UO2) ceramic-metallic (cermet) fuel for nuclear thermal rocket (NTR) propulsion. For the purposes of fissile fuel retention, UO2 spheroids ranging in size from 50 - 100 micrometers (?m) in diameter will be encapsulated in a tungsten shell. The PSS produces spherical particles by melting angular stock particles in an argon-hydrogen plasma jet where they become spherical due to surface tension. Surrogate CeO 2 powder was used in place of UO2 for system and process parameter development. Stock and spheroidized powders were micrographed using optical and scanning electron microscopy and evaluated by statistical methods to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders showed a statistically significant improvement in spherocity, with greater that 60% of the examined particles having an irregularity parameter of equal to or lower than 1.2, compared to stock powder.

Cavender, Daniel

60

Influence of charge states on energies of point defects and clusters in uranium dioxide  

NASA Astrophysics Data System (ADS)

The variation of formation energies of point defects and clusters in uranium dioxide (UO2) as a function of their charge states is studied by density functional theory (DFT). Di- and trivacancies are considered as well as various assemblies of oxygen interstitials, namely the cuboctahedral defect (either empty or filled) and the split-di-interstitial. The energies of formation of these defects for various possible charge states are calculated using the DFT + U approach. The occurrence of multiple minima is circumvented by the use of the U-ramping technique [Meredig , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.82.195128 82, 195128 (2010)]. One finds that point defects and vacancy clusters bear their formal charges, deduced from the ionic picture of bonding in UO2. Conversely, clusters of oxygen interstitials are much less charged than this fully ionic limit. The energy gain upon clustering is vastly modified when the possible charge of defects is taken into account. Vacancy clusters prove only marginally stable compared to their isolated counterparts. Clusters of oxygen interstitials are found energetically unstable with respect to isolated interstitials in the stoichiometric compound.

Crocombette, Jean-Paul

2012-04-01

61

Extraction of uranium from uranium oxides (UO(x)) using beta-diketones and alkyl phosphates dissolved in supercritical carbon dioxide  

NASA Astrophysics Data System (ADS)

In this dissertation, the development of a supercritical fluid extraction (SFE) process for the removal of uranium directly from a solid, crystalline lattice is described. Uranium was chosen as the metal of interest due to its importance to the nuclear industry. While this work was conducted in an attempt to further develop metals extraction using SFE, it has as its main goal the reduction of waste associated with nuclear fuel reprocessing. In this study it was discovered that the beta-diketonate ligand thenoyltrifluoroacetyl-acetone (TTA) was most effective in complexing uranium directly from UOsb3. Approximately 70% of the UOsb3 is converted to uranyl-TTA complex in a typical extraction. Increased solubility of the uranyl-TTA complex (UOsb2(TTA)sb2{*}Hsb2Orbrack was achieved through the formation of adducts with the organophosphorous reagents TBP, TOPO, TPPO and TBPO. In competitive extraction experiments, uranium was efficiently extracted from a mixture of six metal oxides through the formation of UOsb2(TTA)sb2{*}TBP in 2% TBP modified COsb2. Crystal structures of UOsb2(TTA)sb2{*}Hsb2O,\\ UOsb2(TTA)sb2{*}EtOH and UOsb2(TTA)sb2{*}TBP were obtained. The TTA complexes of iron (Fe(TTA)sb3rbrack and thorium (Th(TTA)sb4rbrack were effectively separated from the uranyl complex in SF COsb2 by changing fluid density. It was also shown that the uranyl and thorium complexes could be separated from each other using the same technique. A method for the synthesis of UOsb2(TTA)sb2{*}Hsb2O starting with UOsb3 in hexane is described. A view cell was used to obtain the solubility of acetylacetone (ACAC), trifluoroacetylacetone (TFA), hexafluoroacetylacetone (HFA) and TTA in supercritical fluid (SF) carbon dioxide under varying conditions. Volatility and increased fluorination influence the degree to which each ligand is soluble in SF COsb2. In addition, the equilibrium between the keto and enol tautomers of ACAC, TFA and HFA dissolved in SF COsb2 was determined using sp1H NMR. The observed trends for all ligands studied correlate well with extraction results for this class of compounds.

Phelps, Cindy Lou

62

Uranium industry annual 1994  

SciTech Connect

The Uranium Industry Annual 1994 (UIA 1994) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing during that survey year. The UIA 1994 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the 10-year period 1985 through 1994 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data collected on the ``Uranium Industry Annual Survey`` (UIAS) provide a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1994, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. A feature article, ``Comparison of Uranium Mill Tailings Reclamation in the United States and Canada,`` is included in the UIA 1994. Data on uranium raw materials activities including exploration activities and expenditures, EIA-estimated resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities, including purchases of uranium and enrichment services, and uranium inventories, enrichment feed deliveries (actual and projected), and unfilled market requirements are shown in Chapter 2.

NONE

1995-07-05

63

Ex-Reactor Determination of Thermal Gap Conductance Between Uranium Dioxide and Zircaloy-4  

SciTech Connect

An ex-reactor study of the thermal gap conductance between Uranium Dioxide (UO{sub 2}) and Zircaloy-4 (Zr4) was performed under varying conditions of gas pressure (0.1 to 7 MPa); temperature (283 to 673 K); gas composition (He (100); Ar (100); He:Ar (51.79:48.21); and He:Xe (89.4:10.6)); and, average mean-plane separation distance D{sub mp} = 5.9 {micro}m (light contact); and, D{sub mp} = 23.1 {micro}m). In this report a description of the high pressure autoclave, specimen holder and associated apparatus is given together with experimental results. In conjunction with the experimental apparatus an assessment of determinant and indeterminant errors is made. In this report the predicted gap conductance based on the "ideal" expression for the gap conductance, H{sub g} = K{sub gas}/(d + g{sub 1} + g{sub 2}) and assuming D{sub m}p = d and g{sub 1} = g{sub 2}, is compared to the H{sub g} results and found not to be in agreement. Use of the ideal gap conductance expression under these conditions is seen to under-estimate the value of H{sub g} results. A discussion of possible reasons for the differences between the observed and predicted behavior is made. In addition to experimental errors resulting from gaseous convection, a detailed examination of the ideal gap conductance expression reveals that the basic assumptions (upon which the ideal gap conductance expression is derived) are not valid for real surfaces in close proximity and/or contact.

Garnier, J.; Begej, S.

1980-07-01

64

Bicarbonate leaching of uranium  

SciTech Connect

The alkaline leach process for extracting uranium from uranium ores is reviewed. This process is dependent on the chemistry of uranium and so is independent on the type of mining system (conventional, heap or in-situ) used. Particular reference is made to the geochemical conditions at Crownpoint. Some supporting data from studies using alkaline leach for remediation of uranium-contaminated sites is presented.

Mason, C.

1998-12-31

65

Uranium in Dental Porcelain.  

National Technical Information Service (NTIS)

The radiological health aspects of the use of uranium in dental porcelain are presented. The concentration of uranium is reported for 18 sets of porcelain teeth and 23 samples of porcelain powder. Particle emission rates were obtained for uranium and for ...

D. L. Thompson

1976-01-01

66

PROPERTIES OF URANIUM CARBIDES  

Microsoft Academic Search

Properties of uranium carbides are reviewed and brought up to date. ; Photographs and photomicrographs of uranium carbides fabricated by melting and ; casting techniques and by powder metallurgy techniques are presented. Recent ; data confirm that uranium monocarbide has metallic conductivity (a thermal ; conductivity of approximately 0.055 cal\\/sec-cm- deg C and a resistivity of ; approximately 35 microhm-cm)

W. Chubb; R. F. Dickerson

1962-01-01

67

Fabrication of uranium dioxide ceramic pellets with controlled porosity from oxide microspheres  

NASA Astrophysics Data System (ADS)

This study concerns the fabrication of uranium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Details are given about oxide microsphere synthesis and particularly about loading operation and heat treatments. The fabrication of ceramic pellets is also described and discussed. Results showed that this process allows the preparation of either dense or porous pellets by mixing U3O8 and UO2-like microspheres before pressing and sintering.

Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Dugne, O.; Bisel, I.; Blanchart, P.; Ayral, A.

2014-05-01

68

Probing Surface Oxidation of Reduced Uranium Dioxide Thin Film Using Synchrotron Radiation  

Microsoft Academic Search

The work presents a study of the formation of defects created by argon ion sputtering of UO thin film surfaces using high-resolution X-ray photoelectron spectroscopy with photon energy of 625 eV. Stable-defected surfaces of UO{sub 2-x} were monitored by the uranium core level lines found at the low-binding energy side of the U{sup +4} features. The lower end of these

Sanjaya D Senanayake; G. I. N. Waterhouse; A. S. Y. Chan; T. E. Madey; David R Mullins; H. Idriss

2007-01-01

69

Screened Coulomb interaction calculations: cRPA implementation and applications to dynamical screening and self-consistency in uranium dioxide and cerium  

NASA Astrophysics Data System (ADS)

We report an implementation of the constrained random phase approximation (cRPA) method within the projector augmented-wave framework. It allows for the calculation of the screened interaction in the same Wannier orbitals as our recent DFT+U and DFT+DMFT implementations. We present calculations of the dynamical Coulomb screened interaction in uranium dioxide and ? and ? cerium on Wannier functions. We show that a self-consistent calculation of the static screened interaction in DFT+U together with a consistent Wannier basis is mandatory for ? cerium and uranium dioxide. We emphasize that a static approximation for the screened interaction in ? cerium is too drastic.

Amadon, Bernard; Applencourt, Thomas; Bruneval, Fabien

2014-03-01

70

Method for converting uranium oxides to uranium metal  

DOEpatents

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixtures is then cooled to a temperature less than -100/sup 0/C in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Duerksen, W.K.

1987-01-01

71

Method for converting uranium oxides to uranium metal  

DOEpatents

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Duerksen, Walter K. (Norris, TN) [Norris, TN

1988-01-01

72

Isotopic fractionation of uranium in sandstone  

USGS Publications Warehouse

Relatively unoxidized black uranium ores from sandstone deposits in the western United States show deviations in the uranium-235 to uranium-234 ratio throughout a range from 40 percent excess uranium-234 to 40 percent deficient uranium-234 with respect to a reference uranium-235 to uranium-234 ratio. The deficient uranium-234 is leached preferentially to uranium-238 and the excess uranium-234 is believed to result from deposition of uranium-234 enriched in solutions from leached deposits.

Rosholt, J. N.; Shields, W. R.; Garner, E. L.

1963-01-01

73

THE CONTROL OF URANIUM FIRES  

Microsoft Academic Search

Fires have occurred in the production, storing, handling and shipping of uranium powder and turnings. Batches of uranium powder, swarf and solid scrap have been ignited to observe fire temperatures and combustion rates and materials and methods to suppress or extinguish uranium fires investigated. The effect on various metals in contact with burning uranium has also been examined. The uranium

1952-01-01

74

Probing Surface Oxidation of Reduced Uranium Dioxide Thin Film Using Synchrotron Radiation  

SciTech Connect

The work presents a study of the formation of defects created by argon ion sputtering of UO{sub 2} thin film surfaces using high-resolution X-ray photoelectron spectroscopy with photon energy of 625 eV. Stable-defected surfaces of UO{sub 2-x} were monitored by the uranium core level lines found at the low-binding energy side of the U{sup +4} features. The lower end of these states gave binding energies at 377.1 and 387.7 eV attributed to U4f{sub 7/2} and U4f{sub 5/2} core levels peaks, respectively, for metallic uranium (U{sup {circ}}). In between both states (U{sup {circ}} and U{sup +4}), the clear presence of other electronic states is observed. These lines are attributed to intermediate, metastable states of uranium ions between U{sup {circ}} and U{sup +4}. Temperature-programmed X-ray photoelectron spectroscopy is performed to observe the oxidation process of these reduced states with increasing temperature. The increase in the U{sup +4} intensity is not correlated with the decrease of U ions signal with lower oxidation states indicating that the limitation is the photoelectron escape depth. In other words, sputtering has created reduced clusters or ridges on the surface of average dimensions larger than the escape depth of the 4f photoelectron with kinetic energy of 225 eV. The activation energy for surface oxidation to U{sup +4} is {approx}20 kJ mol{sup -1}. This value is close to other values reported for vacancy-type diffusion mechanism in the fluorite structure.

Senanayake,S.; Waterhouse, G.; Chan, A.; Madey , T.; Mullins, D.; Idriss, H.

2007-01-01

75

Uranium hexafluoride public risk  

SciTech Connect

The limiting value for uranium toxicity in a human being should be based on the concentration of uranium (U) in the kidneys. The threshold for nephrotoxicity appears to lie very near 3 {mu}g U per gram kidney tissue. There does not appear to be strong scientific support for any other improved estimate, either higher or lower than this, of the threshold for uranium nephrotoxicity in a human being. The value 3 {mu}g U per gram kidney is the concentration that results from a single intake of about 30 mg soluble uranium by inhalation (assuming the metabolism of a standard person). The concentration of uranium continues to increase in the kidneys after long-term, continuous (or chronic) exposure. After chronic intakes of soluble uranium by workers at the rate of 10 mg U per week, the concentration of uranium in the kidneys approaches and may even exceed the nephrotoxic limit of 3 {mu}g U per gram kidney tissue. Precise values of the kidney concentration depend on the biokinetic model and model parameters assumed for such a calculation. Since it is possible for the concentration of uranium in the kidneys to exceed 3 {mu}g per gram tissue at an intake rate of 10 mg U per week over long periods of time, we believe that the kidneys are protected from injury when intakes of soluble uranium at the rate of 10 mg U per week do not continue for more than two consecutive weeks. For long-term, continuous occupational exposure to low-level, soluble uranium, we recommend a reduced weekly intake limit of 5 mg uranium to prevent nephrotoxicity in workers. Our analysis shows that the nephrotoxic limit of 3 {mu}g U per gram kidney tissues is not exceeded after long-term, continuous uranium intake at the intake rate of 5 mg soluble uranium per week.

Fisher, D.R.; Hui, T.E.; Yurconic, M.; Johnson, J.R.

1994-08-01

76

Uranium Mill Tailings Management  

SciTech Connect

This book presents the papers given at the Fifth Symposium on Uranium Mill Tailings Management. Advances made with regard to uranium mill tailings management, environmental effects, regulations, and reclamation are reviewed. Topics considered include tailings management and design (e.g., the Uranium Mill Tailings Remedial Action Project, environmental standards for uranium mill tailings disposal), surface stabilization (e.g., the long-term stability of tailings, long-term rock durability), radiological aspects (e.g. the radioactive composition of airborne particulates), contaminant migration (e.g., chemical transport beneath a uranium mill tailings pile, the interaction of acidic leachate with soils), radon control and covers (e.g., radon emanation characteristics, designing surface covers for inactive uranium mill tailings), and seepage and liners (e.g., hydrologic observations, liner requirements).

Nelson, J.D.

1982-01-01

77

Dissolution of uranium dioxide by molten zircaloy. I. Diffusion-controlled reaction  

NASA Astrophysics Data System (ADS)

The morphology, reaction products, kinetics and mechanisms of the reaction of UO 2 with Zircaloy were investigated in laboratory tests at temperatures between 1900 and 2200c and times from 10 to 200 s. To avoid unstable density gradients and the resulting bulk motion of the melt, a disk of UO 2 was used as the bottom of a crucible with walls of thoria to contain the liquid metal. Polished sections of the post-test specimens were examined by optical microscopy, scanning electron microscopy, Auger electron spectroscopy, and electron microprobe analysis. The complicated structures observed in the quenched specimens, which contained up to seven distinct regions, could, with the aid of phase diagrams, be traced to a two-phase interaction region at high temperature. This region arose from inhomogeneous production of metallic uranium in the near-surface part of the oxide, which permitted rapid zirconium penetration of the oxide to depths of hundreds of microns. Kinetic analysis of oxygen and uranium migration into the melt were based on a diffusion model and utilized measured solubilities of these elements in the melt and data on UO 2 specimen thickness decrease and concentration distributions in the specimen.

Tim, K. T.; Olander, D. R.

1988-06-01

78

Preparation of uranium compounds  

DOEpatents

UI.sub.3(1,4-dioxane).sub.1.5 and UI.sub.4(1,4-dioxane).sub.2, were synthesized in high yield by reacting turnings of elemental uranium with iodine dissolved in 1,4-dioxane under mild conditions. These molecular compounds of uranium are thermally stable and excellent precursor materials for synthesizing other molecular compounds of uranium including alkoxide, amide, organometallic, and halide compounds.

Kiplinger, Jaqueline L; Montreal, Marisa J; Thomson, Robert K; Cantat, Thibault; Travia, Nicholas E

2013-02-19

79

Extraction of Uranium from Aqueous Solutions Using Ionic Liquid and Supercritical Carbon Dioxide in Conjunction  

SciTech Connect

Uranyl ions (UO2)2+ in aqueous nitric acid solutions can be extracted into supercritical CO2 (sc-CO2) via an imidazolium-based ionic liquid using tri-n-butylphosphate (TBP) as a complexing agent. The transfer of uranium from the ionic liquid to the supercritical fluid phase was monitored by UV/Vis spectroscopy using a high-pressure fiberoptic cell. The form of the uranyl complex extracted into the supercritical CO2 phase was found to be UO2(NO3)2(TBP)2. The extraction results were confirmed by UV/Vis spectroscopy and by neutron activation analysis. This technique could potentially be used to extract other actinides for applications in the field of nuclear waste management.

Wang, Joanna S.; Sheaff, Chrystal N.; Yoon, Byunghoon; Addleman, Raymond S.; Wai, Chien M.

2009-01-01

80

Extraction of uranium from aqueous solutions by using ionic liquid and supercritical carbon dioxide in conjunction.  

PubMed

Uranyl ions [UO(2)](2+) in aqueous nitric acid can be extracted into supercritical CO(2) (sc-CO(2)) by using an imidazolium-based ionic liquid with tri-n-butyl phosphate (TBP) as a complexing agent. The transfer of uranium from the ionic liquid to the supercritical fluid phase was monitored by UV/Vis spectroscopy using a high-pressure fiber-optic cell. The form of the uranyl complex extracted into the sc-CO(2) phase was identified to be [UO(2)(NO(3))(2)(TBP)(2)]. The extraction results were confirmed by fluorescence spectroscopy and by neutron activation analysis. This technique has potential applications in the field of nuclear waste management for extracting other actinides. PMID:19283821

Wang, Joanna Shaofen; Sheaff, Chrystal N; Yoon, Byunghoon; Addleman, R Shane; Wai, Chien M

2009-01-01

81

Computational Investigation of the Formation of Hyper-stoichiometric Uranium Dioxide (UO{sub 2+x})  

SciTech Connect

Understanding the mechanisms behind the formation of hyper-stoichiometric UO{sub 2} phases is important because oxidation of uranium atoms upon the addition of excess oxygen to the UO{sub 2} structure leads to volume changes that increase the susceptibility of spent fuel to corrosion. While a variety of diffraction and spectroscopic studies have been used to investigate structural changes as UO{sub 2} oxidizes to U{sub 4}O{sub 9}, the effect of interstitial oxygen on the charge distribution of uranium in hyper-stoichiometric UO{sub 2} remains inconclusive. In this study, quantum mechanical techniques were used to model the effects of interstitial oxygen on the structure and charge distribution of atoms in a simplified U{sub 4}O{sub 9} unit cell. A density functional theory-based approach was used to optimize the geometry and charge distribution of a variety of U{sub 4}O{sub 9} starting models with different U{sup 4+}, U{sup 5+} and U{sup 6+} charge configurations. Results from our calculations suggest that the formation of one U{sup 5+} per addition of interstitial oxygen at a perpendicular bisector site is favorable; this oxidation event is accompanied by partial reduction of the interstitial oxygen atom. Deflection of two lattice oxygen atoms along the body diagonal of the cubic site surrounding the U{sup 5+} is also observed upon the addition of one interstitial oxygen atom. Structural and bond length data are compared with experimental data whenever possible. (authors)

Skomurski, Frances; Becker, Udo; Ewing, Rodney [Geological Sciences, University of Michigan, 2534 C.C. Little Building, 1100 North University Ave., Ann Arbor, MI, 48109 (United States)

2007-07-01

82

SELECTIVE DISSOLUTION OF URANIUM IN URANIUM-URANIUM OXIDE MIXTURES  

Microsoft Academic Search

An 8 N solution of Br in ethyl acetate selectively dissolves U metal, ; leaving uranium oxides unattacked. Interfering acids produced by side reactions ; of Br with the solvent are neutralized by MgO, permitting the dissolution period ; to be extended. (auth);

G. F. Brunzie; T. R. Johnson; R. K. Steunenberg

1961-01-01

83

Uranium extraction process  

SciTech Connect

Uranium is extracted from wet process phosphoric acid by extraction with a mixture of a diorganophosphate and a neutral phosphorus compound, which is preferably a triorgano phosphine oxide, in the presence of nitrate to form an organic extract layer containing uranium and an aqueous acid layer, which are separated.

Rose, M.A.

1983-05-03

84

Uranium and Thorium  

ERIC Educational Resources Information Center

The results of President Carter's policy on non-proliferation of nuclear weapons are expected to slow the growth rate in energy consumption, put the development of the breeder reactor in question, halt plans to reprocess and recycle uranium and plutonium, and expand facilities to supply enriched uranium. (Author/MA)

Finch, Warren I.

1978-01-01

85

World Uranium Reserves  

NSDL National Science Digital Library

This American Energy Independence website provides a brief overview of potential supplies of uranium for nuclear energy. The author, nuclear engineer James Hopf, believes that there are large reserves of uranium available, and that more will be discovered if needed. Links to literature cited and related resources are included.

Hopf, James; Independence, American E.

86

SOLUBILITY CHARACTERIZATION OF AIRBORNE URANIUM FROM A URANIUM RECYCLING PLANT  

Microsoft Academic Search

Solubility profiles of uranium dusts in a uranium r ecycling plant were determined by performing in vitro solubility tests on breathing zone air samples con ducted in all process areas of the processing plant. The recycling plant produces hig h density shields, closed end tubes that are punch and formed from uranium sheet metal, and high-fired uranium oxide which is

Robert Metzger; Leslie Cole

2004-01-01

87

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM RECOVERY PROCESSED RELATIVELY PURE MATERIALS AND SOLUTIONS AND SOLID RESIDUES WITH RELATIVELY LOW URANIUM CONTENT. URANIUM RECOVERY INVOLVED BOTH SLOW AND FAST PROCESSES. (4/4/66) - Rocky Flats Plant, General Manufacturing, Support, Records-Central Computing, Southern portion of Plant, Golden, Jefferson County, CO

88

Uranium dioxide in ionic liquid with a tri-n-butylphosphate-HNO3 complex--dissolution and coordination environment.  

PubMed

Uranium dioxide can be dissolved directly in an imidazolium-based ionic liquid (IL) at room temperature with a tri-n-butylphosphate(TBP)-HNO(3) complex. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies show the dissolved uranyl ions are coordinated with TBP in the IL phase with a molar ratio of (UO(2))(2+) : TBP = 1 : 2. The dissolved uranyl species can be effectively transferred to a supercritical fluid carbon dioxide (sc-CO(2)) phase. No aqueous phase is formed in either the IL dissolution or the supercritical fluid extraction process. Absorption spectra of the extracted uranyl species in the sc-CO(2) phase suggests the presence of a UO(2)(TBP)(2)(NO(3))(2) and HNO(3) adduct probably of the form UO(2)(TBP)(2)(NO(3))(2)HNO(3). The adduct dissociates in a water-dodecane trap solution during pressure reduction resulting in UO(2)(TBP)(2)(NO(3))(2) collected in the dodecane phase. PMID:21445434

Wai, Chien M; Liao, Yu-Jung; Liao, Weisheng; Tian, Guoxin; Addleman, Raymond S; Quach, Donna; Pasilis, Sofie P

2011-05-14

89

Charge distribution and oxygen diffusion in hyperstoichiometric uranium dioxide UO2+x (x ? 0.25)  

NASA Astrophysics Data System (ADS)

Quantum-mechanical techniques were used to determine the charge distribution of U atoms in UO2+x (x ? 0.25) and to calculate activation-energy barriers to oxygen diffusion. Upon optimization, the reduction in unit-cell volume relative to UO2, and the shortest and bond-lengths (0.22 and 0.24 nm, respectively) are in good agreement with experimental data. The addition of interstitial oxygen to the unoccupied cubic sites in the UO2 structure deflects two nearest-neighbor oxygen atoms along the body diagonal of uranium-occupied cubic sites, creating lattice oxygen defects. In (1 1 2) supercells, the partial oxidation of two U4+ atoms is observed for every interstitial oxygen added to the structure, consistent with previous quantum-mechanical studies. Results favor the stabilization of two U5+ over one U6+ in UO2+x. Calculated activation energies (2.06-2.73 eV) and diffusion rates for oxygen in UO2+x support the idea that defect clusters likely play an increasingly important role as oxidation proceeds.

Skomurski, F. N.; Wang, J. W.; Ewing, R. C.; Becker, U.

2013-03-01

90

Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium dioxide at high temperatures  

NASA Astrophysics Data System (ADS)

Thermodynamic functions of the gaseous species, thermodynamic functions of the condensed phase, and an oxygen-potential model have been combined to calculate the vapor pressures and vapor compositions in equilibrium with condensed-phase UO 2-x for 1500?T?6000 K and 0? x ?0.5. A method for extending the oxygen-potential model of Blackburn to the liquid region has been derived and evaluated. Results of these calculations show that the oxygen-to-uranium ratio of the vapor is larger than that of the condensed phase with which it is in equilibrium for most of the ranges of T and x of interest. Near 6000 K the vapor is very oxygen-rich so that the composition of the condensed phase would be changed considerably by even a few percent vaporization. In general, the vapor in equilibrium with UO 2-x is poorly approximated at UO 2(g); the species U, UO, UO 3, O 2, and O each have higher partial pressures than UO 2 for some conditions. The calculated total pressures at high temperatures are in good agreement with those recommended by the International Working Group on Fast Reactors (IWGFR).

Green, David W.; Leibowitz, Leonard

1982-02-01

91

India's Worsening Uranium Shortage  

SciTech Connect

As a result of NSG restrictions, India cannot import the natural uranium required to fuel its Pressurized Heavy Water Reactors (PHWRs); consequently, it is forced to rely on the expediency of domestic uranium production. However, domestic production from mines and byproduct sources has not kept pace with demand from commercial reactors. This shortage has been officially confirmed by the Indian Planning Commissions Mid-Term Appraisal of the countrys current Five Year Plan. The report stresses that as a result of the uranium shortage, Indian PHWR load factors have been continually decreasing. The Uranium Corporation of India Ltd (UCIL) operates a number of underground mines in the Singhbhum Shear Zone of Jharkhand, and it is all processed at a single mill in Jaduguda. UCIL is attempting to aggrandize operations by establishing new mines and mills in other states, but the requisite permit-gathering and development time will defer production until at least 2009. A significant portion of Indias uranium comes from byproduct sources, but a number of these are derived from accumulated stores that are nearing exhaustion. A current maximum estimate of indigenous uranium production is 430t/yr (230t from mines and 200t from byproduct sources); whereas, the current uranium requirement for Indian PHWRs is 455t/yr (depending on plant capacity factor). This deficit is exacerbated by the additional requirements of the Indian weapons program. Present power generation capacity of Indian nuclear plants is 4350 MWe. The power generation target set by the Indian Department of Atomic Energy (DAE) is 20,000 MWe by the year 2020. It is expected that around half of this total will be provided by PHWRs using indigenously supplied uranium with the bulk of the remainder provided by breeder reactors or pressurized water reactors using imported low-enriched uranium.

Curtis, Michael M.

2007-01-15

92

Uranium Mill Tailings.  

National Technical Information Service (NTIS)

This bibliography contains information on uranium mill tailings included in the Department of Energy's Energy Data Base from January 1981 through October 1982. The abstracts are grouped by subject category as shown in the table of contents. Entries in the...

L. H. McLaren

1982-01-01

93

Uranium purchases report 1994  

SciTech Connect

US utilities are required to report to the Secretary of Energy annually the country of origin and the seller of any uranium or enriched uranium purchased or imported into the US, as well as the country of origin and seller of any enrichment services purchased by the utility. This report compiles these data and also contains a glossary of terms and additional purchase information covering average price and contract duration. 3 tabs.

NONE

1995-07-01

94

Neurotoxicity of depleted uranium  

Microsoft Academic Search

Depleted uranium (DU) is a byproduct of the enrichment process of uranium for its more radioactive isotopes to be used in\\u000a nuclear energy. Because DU is pyrophoric and a dense metal with unique features when combined in alloys, it is used by the\\u000a military in armor and ammunitions. There has been significant public concern regarding the use of DU by

George C.-T. Jiang; Michael Aschiner

2006-01-01

95

Soviet uranium supply capability  

SciTech Connect

For many years, only limited information concerning uranium deposits in the USSR has been available from Soviet sources. The Soviet Union has, however, cooperated in some past efforts to promote interaction with the international scientific community. For example, in 1984 the Soviet Union hosted the 27th International Geological Congress (IGC). The uranium portion included 50 papers, primarily on uranium deposits in sandstone and metamorphic rocks, presented to about 300 members. The IGC sponsored almost 400 geology field trips, the most noteworthy of which was a five-day trip to the Krivoi Rog iron and uranium district in the south-central Ukraine, including visits to two open-pit iron mines and the underground Novaya uranium mine in Zholtye Vody. That conference was reported in detail on the October 1984 NUEXCO Monthly Report. Some other information that has been made available over the years is contained in the April 1985 Report discussion of uranium deposit classifications. Advanced processing technology, low-cost labor, by-product and co-product recovery, and the large existing production capacity enable MAEI to produce nuclear fuel at low cost. The Soviet Union`s reserve base, technological development, and production experience make it one of the world`s leading producers of nuclear fuel. As additional information is made available for publication, NUEXCO will present updated reports on the nuclear fuel cycle facilities in the Soviet Union.

NONE

1990-02-01

96

Determination of uranium-235 by a delayed neutron counting technique  

SciTech Connect

Annual progress report for the period July 1972 through June Determination of /sup 235/U in uranium dioxide-- thorium dioxide mixtures and pyrocarbon- and silicon carbide-coated uranium-- thorium carbide fuel beads was carried out by bombarding with thermal neutrons and counting the delayed neutrons arising from fission of the /sup 235/U. The precision and accuracy of some results are given. (auth)

Hagenauer, R.C.; Zyskowski, C.L.; Nelson, L.C. Jr.

1973-09-01

97

Enhanced thermal conductivity of uranium dioxide-silicon carbide composite fuel pellets prepared by Spark Plasma Sintering (SPS)  

NASA Astrophysics Data System (ADS)

Uranium dioxide (UO2)-10 vol% silicon carbide (SiC) composite fuel pellets were produced by oxidative sintering and Spark Plasma Sintering (SPS) at a range of temperatures from 1400 to 1600 C. Both SiC whiskers and SiC powder particles were utilized. Oxidative sintering was employed over 4 h and the SPS sintering was employed only for 5 min at the highest hold temperature. It was noted that composite pellets sintered by SPS process revealed smaller grain size, reduced formation of chemical products, higher density, and enhanced interfacial contact compared to the pellets made by oxidative sintering. For given volume of SiC, the pellets with powder particles yielded a smaller grain size than pellets with SiC whiskers. Finally thermal conductivity measurements at 100 C, 500 C, and 900 C revealed that SPS sintered UO2-SiC composites exhibited an increase of up to 62% in thermal conductivity compared to UO2 pellets, while the oxidative sintered composite pellets revealed significantly inferior thermal conductivity values. The current study points to the improved processing capabilities of SPS compared to oxidative sintering of UO2-SiC composites.

Yeo, S.; Mckenna, E.; Baney, R.; Subhash, G.; Tulenko, J.

2013-02-01

98

Relatively Inert Material for Casting Uranium and Uranium Alloys.  

National Technical Information Service (NTIS)

Uranium and uranium alloys are typically induction melted in graphite crucibles under vacuum; but because of the chemical reactivity of the metal and the alloy constituents with graphite, crucibles must be protected with a nonreactive coating. Over the ye...

L. R. Walker C. E. Holcombe W. M. Swartout K. A. Thompson

1986-01-01

99

A study of chemical parameters of the internal gelation based sol-gel process for uranium dioxide  

NASA Astrophysics Data System (ADS)

Internal gelation process is one of the important sol-gel routes for the preparation of spherical particles of fuel materials. Successful preparation of defect free fuel particles has been reported only with a narrow range of feed solution compositions. Investigations have been carried out to study the gelation behaviour of solutions containing uranyl nitrate, hexamethylene-tetramine (hexa) and urea with a view to defining the regions of possible interest to the process. A gelation field diagram has been constructed defining regions where a single phase gel can be readily obtained. A number of compositions from this gelation field diagram have been used for the preparation of UO 2 microspheres and it was observed that good spherical particles could be obtained with uranium concentrations ranging from 0.7 to 1.5 molar. The mole ratio (hexa, urea)/uranium for obtaining good particles decreased with increasing uranium concentration.

Vaidya, V. N.; Mukherjee, S. K.; Joshi, J. K.; Kamat, R. V.; Sood, D. D.

1987-05-01

100

Evaluation of a titanium dioxide-based DGT technique for measuring inorganic uranium species in fresh and marine waters.  

PubMed

A new diffusive gradients in a thin film (DGT) technique for measuring dissolved uranium (U) in freshwater is reported. The new method utilises a previously described binding phase, Metsorb (a titanium dioxide based adsorbent). This binding phase was evaluated and compared to the well-established Chelex-DGT method. Batch experiments showed quantitative uptake (1003%) of dissolved U by Metsorb and an elution efficiency of 95% was obtained using a mixed eluent of 1 mol L(-1) NaOH/1 mol L(-1) H(2)O(2). The mass of U accumulated by Metsorb was linear (R(2)?0.98) with time across the pH range 3.0-8.1, validating the DGT measurement. The measured effective diffusion coefficients were highly dependent on pH, ranging from 2.74-4.8110(-6)cm(2)s(-1), which were in reasonable agreement with values from the literature. Ionic strength showed no effect on the uptake of U, and thereby on diffusion coefficients, at NaNO(3) concentrations ?0.01 mol L(-1), but caused the U concentration to be underestimated by 18% and 24% at 0.1 mol L(-1) NaNO(3) and 0.7 mol L(-1) NaNO(3), respectively. Deployment of Metsorb-DGT in synthetic freshwater resulted in reliable measurement of the dissolved U concentration (C(DGT)/C(Sol)=1.05), whereas Chelex-DGT significantly underestimated the dissolved U concentration (C(DGT)/C(Sol)=0.76). Metsorb-DGT was found to give reliable results after 8h deployments in synthetic seawater but experienced competition effects with longer deployments. The Chelex-DGT was unable to measure U at all in synthetic seawater. A field deployment in a freshwater stream (Coomera River) confirmed the utility of the Metsorb-DGT method for measuring U in natural freshwaters, but performance of field deployments may require further evaluation due to the possibility of major changes in uranium speciation with pH and water composition. We recommend a filtered sample, of any water in which DGT measurements are to be made, be used to determine the appropriate diffusion coefficient under controlled laboratory conditions. PMID:22841121

Hutchins, Colin M; Panther, Jared G; Teasdale, Peter R; Wang, Feiyue; Stewart, Ryan R; Bennett, William W; Zhao, Huijun

2012-08-15

101

Preparation of uranium standard solutions for x-ray fluorescence analysis  

Microsoft Academic Search

A method has been developed for gravimetrically preparing uranium nitrate standards with an estimated mean error of 0.1% (1 sigma) and a maximum error of 0.2% (1 sigma) for the total uranium weight. Two source materials, depleted uranium dioxide powder and NBS Standard Reference Material 960 uranium metal, were used to prepare stock solutions. The NBS metal proved to be

C. M. Wong; J. L. Cate; W. L. Pickles

1978-01-01

102

Uranium: Politics, politics, politics  

SciTech Connect

The world uranium market became much more complex in 1992 when actions of the US Dept. of Commerce resulted in the development of a two-tiered pricing system. These governmental actions severely restrict uranium imports from the Commonwealth of Independent States (CIS) into the United States. Consequently, prices in the restricted US market have increased modestly, to about $10/lb U[sub 3]O[sub 8], while non-US prices have declined slightly to somewhat less than $8/lb U[sub 3]O[sub 8]. World uranium production, which is becoming increasingly well-defined as additional information trickles out of the former Eastern Bloc, declined by about 12% from 1991 levels, to 93.4 million lb U[sub 3]O[sub 8]. Consumption remained steady at 145 million lb/yr U[sub 3]O[sub 8]. This growing supply-demand gap would auger well for the uranium industry were it not for a substantial overhang of excess inventory and potential additions from nuclear disarmament. A reasonable supply-demand balance is unlikely to occur before the turn of the century. The effects of weapons conversion on the uranium market are discussed.

Pool, T.C.

1993-03-01

103

Uranium deposits of Brazil  

SciTech Connect

Brazil is a country of vast natural resources, including numerous uranium deposits. In support of the country`s nuclear power program, Brazil has developed the most active uranium industry in South America. Brazil has one operating reactor (Angra 1, a 626-MWe PWR), and two under construction. The country`s economic challenges have slowed the progress of its nuclear program. At present, the Pocos de Caldas district is the only active uranium production. In 1990, the Cercado open-pit mine produced approximately 45 metric tons (MT) U{sub 3}O{sub 8} (100 thousand pounds). Brazil`s state-owned uranium production and processing company, Uranio do Brasil, announced it has decided to begin shifting its production from the high-cost and nearly depleted deposits at Pocos de Caldas, to lower-cost reserves at Lagoa Real. Production at Lagoa Real is schedules to begin by 1993. In addition to these two districts, Brazil has many other known uranium deposits, and as a whole, it is estimated that Brazil has over 275,000 MT U{sub 3}O{sub 8} (600 million pounds U{sub 3}O{sub 8}) in reserves.

NONE

1991-09-01

104

Uranium hexafluoride handling. Proceedings  

SciTech Connect

The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF{sub 6} from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.

Not Available

1991-12-31

105

Uranium-titanium-niobium alloy  

Microsoft Academic Search

This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

Ludtka

1990-01-01

106

Uranium-titanium-niobium alloy  

SciTech Connect

This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

Ludtka, G.M.

1990-11-06

107

Lung Cancer in Uranium Miners.  

National Technical Information Service (NTIS)

This paper analyese the clinical data of 39 uranium miners with lung cancer and of 20 patients with lung cancer who have not been exposed to uranium as control. The age of uranium miners with lung cancer was 36-61 with an average of 48.8, nine years earli...

Zhou C. Fan J. Wang L. Huang Y. Nie G

1987-01-01

108

URANIUM IN EASTERN NEW MEXICO  

Microsoft Academic Search

Known uranium occurrences in eastern New Mexico are all small; total production of uranium ore is less than 50 tons and reserves are a few hundred tons. The most numerous and largest deposits are near the base of the middle fluviatile sand- stone member of the Chinle Formation of Late Triassic age. Uranium deposits of ore grade occur in the

WARREN I. FINCH

109

Corrosion-resistant uranium  

DOEpatents

The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

Hovis, Jr., Victor M. (Kingston, TN); Pullen, William C. (Knoxville, TN) [Knoxville, TN; Kollie, Thomas G. (Oak Ridge, TN) [Oak Ridge, TN; Bell, Richard T. (Knoxville, TN) [Knoxville, TN

1983-01-01

110

Corrosion-resistant uranium  

DOEpatents

The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

Hovis, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

1981-10-21

111

Solubility characterization of airborne uranium from a uranium recycling plant.  

PubMed

Solubility profiles of uranium dusts in a uranium recycling plant were determined by performing in vitro solubility tests on breathing zone air samples conducted in all process areas of the processing plant. The recycling plant produces high density shields, closed end tubes that are punched and formed from uranium sheet metal, and high-fired uranium oxide, which is used as a catalyst. The recycled uranium is cut and melted in a vacuum furnace, and part of the molten uranium is poured into molds for further processing. Air samples were taken in process areas under normal working conditions. The dissolution rate of the uranium in a simulant solution of extracellular airway lining fluid (Gamble's solution) was then determined over the next 28 d. Airborne uranium in the oxide section of the plant was found to be highly insoluble with 99% of the uranium having a dissolution half time in excess of 100 d. The solubility of the airborne uranium in other areas of the facility was only slightly more soluble with over 90% of the airborne uranium having dissolution half times in excess of 90 d. PMID:15194928

Metzger, Robert; Cole, Leslie

2004-07-01

112

Inhibition of uranium(VI) sorption on titanium dioxide by surface iron(III) species in ferric oxide/titanium dioxide systems.  

PubMed

Uranium (U(VI)) sorption in systems containing titanium dioxide (TiO(2)) and various Fe(III)-oxide phases was investigated in the acidic pH range (pH 2.5-6). Studies were conducted with physical mixtures of TiO(2) and ferrihydrite, TiO(2) with coprecipitated ferrihydrite, and with systems where Fe(III) was mostly present as crystalline Fe(III) oxides. The presence of ferrihydrite resulted in decreased U(VI) sorption relative to the pure TiO(2) systems, particularly below pH 4, an unexpected result given that the presence of another sorbent would be expected to increase U(VI) uptake. In mixtures of TiO(2) and crystalline Fe(III) oxide phases, U(VI) sorption was higher than for the analogous mixtures of TiO(2) with ferrihydrite, and was similar to U(VI) sorption on TiO(2) alone. X-ray absorption spectroscopy of the TiO(2) system with freshly precipitated Fe(III) oxides indicated the presence of an Fe(III) surface phase that inhibits U(VI) sorption-a reaction whereby Fe(III) precipitates as lepidocrocite and/or ferrihydrite effectively blocking surface sorption sites on the underlying TiO(2). Competition between dissolved Fe(III) and U(VI) for sorption sites may also contribute to the observed decrease in U(VI) sorption. The present study demonstrates the complexity of sorption in mixed systems, where the oxide phases do not necessarily behave in an additive manner, and has implications for U(VI) mobility in natural and impacted environments where Fe(III) (oxyhydr)oxides are usually assumed to increase the retention of U(VI). PMID:23013221

Comarmond, M Josick; Payne, Timothy E; Collins, Richard N; Palmer, Gabriel; Lumpkin, Gregory R; Angove, Michael J

2012-10-16

113

Method of preparation of uranium nitride  

DOEpatents

Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

2013-07-09

114

Control of uranium hazards - Portsmouth uranium enrichment plant  

SciTech Connect

This report summarizes the Environmental, Safety and Health programs to control uranium hazards at the Portsmouth Gaseous Diffusion Plant. A description of the physical plant, the facility processes and the attendant uranium flows and effluents are provided. The hazards of uranium are discussed and the control systems are outlined. Finally, the monitoring programs are described and summaries of recent data are provided. 11 figs., 20 tabs.

Wagner, E.R.

1985-11-01

115

Trace determination of uranium, thorium, calcium, and other heavy metals in high-purity refractory metal silicides, niobium, and silicon dioxide with isotope dilution mass spectrometry  

SciTech Connect

A method for the determination of trace impurities (U, Th, Ca, Fe, Cr, Ni, Cu, and Cd) in silicides of refractory metals, in niobium, and in silicon dioxide with isotope dilution mass spectrometry (IDMS) has been developed. This method enables uranium and thorium analyses down to the lowest picogram per gram level with high precision and accuracy, which is especially important for the characterization of microelectronic devices. The other elements can be determined down to the low nanogram per gram level or - depending on the blank values - in some cases less. Selective chromatographic, extractive, and electrolytic procedures for the trace-matrix-separation were combined with positive thermal ionization mass spectrometry. Different samples of high-purity materials (metal and silicide powders, compact silicide, and silicon dioxide powder) for advanced technologies were analyzed.

Herzner, P.; Heumann, K.G. (Universitaet Regensburg (Germany))

1992-12-01

116

Method for fabricating uranium foils and uranium alloy foils  

DOEpatents

A method of producing thin foils of uranium or an alloy. The uranium or alloy is cast as a plate or sheet having a thickness less than about 5 mm and thereafter cold rolled in one or more passes at substantially ambient temperatures until the uranium or alloy thereof is in the shape of a foil having a thickness less than about 1.0 mm. The uranium alloy includes one or more of Zr, Nb, Mo, Cr, Fe, Si, Ni, Cu or Al.

Hofman, Gerard L. (Downers Grove, IL); Meyer, Mitchell K. (Idaho Falls, ID); Knighton, Gaven C. (Moore, ID); Clark, Curtis R. (Idaho Falls, ID)

2006-09-05

117

Uranium price forecasting methods  

SciTech Connect

This article reviews a number of forecasting methods that have been applied to uranium prices and compares their relative strengths and weaknesses. The methods reviewed are: (1) judgemental methods, (2) technical analysis, (3) time-series methods, (4) fundamental analysis, and (5) econometric methods. Historically, none of these methods has performed very well, but a well-thought-out model is still useful as a basis from which to adjust to new circumstances and try again.

Fuller, D.M.

1994-03-01

118

Sputtering of uranium  

NASA Technical Reports Server (NTRS)

Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

Gregg, R.; Tombrello, T. A.

1978-01-01

119

Depleted Uranium in Repositories  

SciTech Connect

For uranium to be useful in most fission nuclear reactors, it must be enriched (i.e. the concentration of the fissile isotope 235U must be increased). Therefore, depleted uranium (DU)-uranium which has less than naturally occurring concentrations of 235U-is a co-product of the enrichment process. Four to six tons of DU exist for every ton of fresh light water reactor fuel. There were 407,006 MgU 407,000 metric tons (t) of DU stored on U.S. Department of Energy (DOE) sites as of July 1993. If this DU were to be declared surplus, converted to a stable oxide form, and emplaced in a near surface disposal facility, the costs are estimated to be several billion dollars. However, the U.S. Nuclear Regulatory Commission has stated that near surface disposal of large quantities of DU tails is not appropriate. Thus, there is the possibility that disposition via disposal will be in a deep geological repository. One alternative that may significantly reduce the cost of DU disposition is to use it beneficially. In fact, DOE has begun the Beneficial Uses of DU Project to identify large scale uses of DU and to encourage its reuse. Several beneficial uses, many of which involve applications in the repository per se or in managing the wastes to go into the repository, are discussed in this report.

Haire, M.J.; Croff, A.G.

1997-12-31

120

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2013 CFR

...ASSETS CONTROL REGULATIONS General Definitions § 540.309 Natural uranium. The term natural uranium means uranium found in nature, with an average concentration of 0.711 percent by weight of the isotope...

2013-07-01

121

Uranium Mill Tailings Remedial Action Technology.  

National Technical Information Service (NTIS)

The uranium milling process involves the hydrometallurgical extraction of uranium from ores and the resultant generation of large quantities of waste referred to as tailings. Uranium mill tailings have been identified as requiring remediation because they...

J. N. Hartley G. W. Gee

1984-01-01

122

Uranium droplet core nuclear rocket  

NASA Technical Reports Server (NTRS)

Uranium droplet nuclear rocket is conceptually designed to utilize the broad temperature range ofthe liquid phase of metallic uranium in droplet configuration which maximizes the energy transfer area per unit fuel volume. In a baseline system dissociated hydrogen at 100 bar is heated to 6000 K, providing 2000 second of Isp. Fission fragments and intense radian field enhance the dissociation of molecular hydrogen beyond the equilibrium thermodynamic level. Uranium droplets in the core are confined and separated by an axisymmetric vortex flow generated by high velocity tangential injection of hydrogen in the mid-core regions. Droplet uranium flow to the core is controlled and adjusted by a twin flow nozzle injection system.

Anghaie, Samim

1991-01-01

123

Developments in uranium in 1986  

SciTech Connect

Imported uranium and low prices continued to plague the domestic uranium industry and, as a result, the Secretary of Energy declared the domestic industry to be nonviable for the second straight year. Uranium exploration expenditures in the US declined for the eighth consecutive year. In 1986, an estimated $19 million was spent on uranium exploration, including 1.9 million ft of surface drilling. This drilling was done mainly in producing areas and in areas of recent discoveries. Production of uranium concentrate increased in 1986, when 13.8 million lb of uranium oxide (U/sub 3/O/sub 8/) were produced, a 22% increase over 1985. Uranium produced as the result of solution mining and as the by-product of phosphoric acid production accounted for about 37% of the total production in the US. At the end of 1986, only 6 uranium mills were operating in the US. Canada continued to dominate the world market. The development under way at the huge Olympic Dam deposit in Australia will increase that country's production. US uranium production is expected to show a small decrease in 1987. 3 figures, 2 tables.

Chenoweth, W.L.

1987-10-01

124

Oxidation states of uranium in depleted uranium particles from Kuwait  

Microsoft Academic Search

The oxidation states of uranium in depleted uranium (DU) particles were determined by synchrotron radiation based ?-XANES, applied to individual particles isolated from selected samples collected at different sites in Kuwait. Based on scanning electron microscopy with X-ray microanalysis prior to ?-XANES, DU particles ranging from submicrons to several hundred micrometers were observed. The median particle size depended on sources

B. Salbu; K. Janssens; O. C. Lind; K. Proost; L. Gijsels; P. R. Danesi

2004-01-01

125

12. VIEW OF DEPLETED URANIUM INGOT AND MOLDS. DEPLETED URANIUM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. VIEW OF DEPLETED URANIUM INGOT AND MOLDS. DEPLETED URANIUM CASTING OPERATIONS CEASED IN 1988. (11/14/57) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO

126

Extraction of uranium from spent fuels using liquefied gases  

SciTech Connect

For reprocessing of spent nuclear fuels, a novel method to extract actinides from spent fuel using highly compressed gases, nitrogen dioxide and carbon dioxide was proposed. As a fundamental study, the nitrate conversion with liquefied nitrogen dioxide and the nitrate extraction with supercritical carbon dioxide were demonstrated by using uranium dioxide powder, uranyl nitrate and tri-n-butylphosphate complex in the present study. (authors)

Sawada, Kayo; Hirabayashi, Daisuke; Enokida, Youichi [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

2007-07-01

127

Method for fluorination of uranium oxide  

DOEpatents

Highly pure uranium hexafluoride is made from uranium oxide and fluorine. The uranium oxide, which includes UO.sub.3, UO.sub.2, U.sub.3 O.sub.8 and mixtures thereof, is introduced together with a small amount of a fluorine-reactive substance, selected from alkali chlorides, silicon dioxide, silicic acid, ferric oxide, and bromine, into a constant volume reaction zone. Sufficient fluorine is charged into the zone at a temperature below approximately 0.degree. C. to provide an initial pressure of at least approximately 600 lbs/sq. in. at the ambient atmospheric temperature. The temperature is then allowed to rise in the reaction zone until reaction occurs.

Petit, George S. (Oak Ridge, TN)

1987-01-01

128

Solubility measurement of uranium in uranium-contaminated soils  

SciTech Connect

A short-term equilibration study involving two uranium-contaminated soils at the Fernald site was conducted as part of the In Situ Remediation Integrated Program. The goal of this study is to predict the behavior of uranium during on-site remediation of these soils. Geochemical modeling was performed on the aqueous species dissolved from these soils following the equilibration study to predict the on-site uranium leaching and transport processes. The soluble levels of total uranium, calcium, magnesium, and carbonate increased continually for the first four weeks. After the first four weeks, these components either reached a steady-state equilibrium or continued linearity throughout the study. Aluminum, potassium, and iron, reached a steady-state concentration within three days. Silica levels approximated the predicted solubility of quartz throughout the study. A much higher level of dissolved uranium was observed in the soil contaminated from spillage of uranium-laden solvents and process effluents than in the soil contaminated from settling of airborne uranium particles ejected from the nearby incinerator. The high levels observed for soluble calcium, magnesium, and bicarbonate are probably the result of magnesium and/or calcium carbonate minerals dissolving in these soils. Geochemical modeling confirms that the uranyl-carbonate complexes are the most stable and dominant in these solutions. The use of carbonate minerals on these soils for erosion control and road construction activities contributes to the leaching of uranium from contaminated soil particles. Dissolved carbonates promote uranium solubility, forming highly mobile anionic species. Mobile uranium species are contaminating the groundwater underlying these soils. The development of a site-specific remediation technology is urgently needed for the FEMP site.

Lee, S.Y.; Elless, M.; Hoffman, F.

1993-08-01

129

SEPARATION OF URANIUM AND THORIUM  

Microsoft Academic Search

A simple and direct ion-exchange method has been suggested for the ; separation of uranium from thorium. Both the elements are absorbed by the resin ; (Amberlite lR) from which uranium can be eluted first with 1.70 M hydrochloric ; acid. After neutralizing the acid by running ammonia solution through the resin ; column, thorium is eluted with l.1 M

S. V. Suryanarayana; Bh. S. V. R. RaO

1958-01-01

130

METHOD OF DISSOLVING URANIUM METAL  

Microsoft Academic Search

This patent relates to an economicai means of dissolving metallic ; uranium. It has been found that the addition of a small amount of perchloric ; acid to the concentrated nitric acid in which the uranium is being dissolved ; greatly shortens the time necessary for dissolution of the metal. Thus the use ; of about 1 or 2 percent

Slotin

1958-01-01

131

Compensation of Navajo Uranium Miners  

NSDL National Science Digital Library

This site addresses policy issues of the compensation of Navajo uranium miners. The site provides an annotated index of current issues, legislation, papers and presentations, books, and links that lead to more information on uranium miners. Imbedded links throughout the text lead to related information.

Project, World I.

132

Emission of Neutrons by Uranium  

Microsoft Academic Search

Fast neutrons emitted by uranium under the action of thermal neutrons were studied by using a radium-beryllium photoneutron source. The background due to the primary neutrons can be neglected since only a few of the photoneutrons are sufficiently fast to be counted. Data are obtained concerning the energy spectrum of the uranium fission neutrons by recording photographically by means of

W. H. Zinn; Leo Szilard

1939-01-01

133

Aluminosilicate Precipitation Impact on Uranium  

SciTech Connect

Experiments have been conducted to examine the fate of uranium during the formation of sodium aluminosilicate (NAS) when wastes containing high aluminate concentrations are mixed with wastes of high silicate concentration. Testing was conducted at varying degrees of uranium saturation. Testing examined typical tank conditions, e.g., stagnant, slightly elevated temperature (50 C). The results showed that under sub-saturated conditions uranium is not removed from solution to any large extent in both simulant testing and actual tank waste testing. This aspect was not thoroughly understood prior to this work and was necessary to avoid criticality issues when actual tank wastes were aggregated. There are data supporting a small removal due to sorption of uranium on sites in the NAS. Above the solubility limit the data are clear that a reduction in uranium concentration occurs concomitant with the formation of aluminosilicate. This uranium precipitation is fairly rapid and ceases when uranium reaches its solubility limit. At the solubility limit, it appears that uranium is not affected, but further testing might be warranted.

WILMARTH, WILLIAM

2006-03-10

134

Developments in uranium in 1987  

SciTech Connect

Legal and political factors, imports, and low prices continued to plague the domestic uranium industry. As a result, the Secretary of Energy in 1987 declared the domestic industry to be nonviable for the third straight year. Uranium exploration expenditures in the US declined for the ninth consecutive year. In 1987, an estimated $18 million was spent on uranium exploration, including 1.9 million ft of surface drilling. This drilling was done mainly in production areas and in areas of recent discoveries. Production of uranium concentrate decreased slightly in 1987, when 12.5 million lb of uranium oxide (U/sub 3/O/sub 8/) were produced, a 7% decrease from 1986. Uranium produced from mine water, solution mining, and as the byproduct of phosphoric acid and copper production accounted for about 38% of the total production in the US. At the end of 1987, only 5 uranium mills were operating in the US. The large, high-grade reserves being discovered and developed in Saskatchewan will enable Canada to dominate the world market for many years. Development of the Olympic Dam deposit continued in Australia and will being production in 1988. US uranium production is expected to increase slightly in 1988, as a new open-pit mine begin production. 3 figs., 2 tabs.

Chenoweth, W.L.

1988-10-01

135

Deradiating the former uranium capital  

SciTech Connect

The city that once proclaimed itself The Uranium Capital of America is in the process of divorcing itself from the radioactive element - literally as well as symbolically. The last vestiges of uranium are being shoveled from the community. The removal is part of the federal Department of Energy's (DOE) Remedial Action program. It was established in 1972 to clean up areas of the country in which radiation exposure in excess of normal background levels could be attributed to wastes from DOE-operated uranium processing plants. Grand Junction was the first area to qualify. A good portion of the city is built on radioactive tailings - by-products of a uranium-processing industry. The DOE and the Environmental Protection Agency established guidelines for action levels of radiation. The standards were extrapolated from data from studies of lung cancer incidence in uranium miners in Europe and the US.

Merz, B.

1987-08-07

136

Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle  

NASA Astrophysics Data System (ADS)

The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (UO2) particle is built. The adsorption effect of the fission product on the surface of the UO2 particle and the delayed decay effect are also considered. The solution is given in terms of MittagLeffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor.

Fang, Chao; Cao, Jian-Zhu; Sun, Li-Feng

2011-05-01

137

Uranium in river water  

SciTech Connect

The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

Palmer, M.R. (Univ. of Bristol (United Kingdom)); Edmond, J.M. (Massachusetts Inst. of Technology, Cambridge, MA (United States))

1993-10-01

138

Uranium and plutonium isotopes in the atmosphere  

Microsoft Academic Search

Uranium 234 and 235 were found to be highly enriched relative to uranium 238 in several rain samples collected at Fayetteville, Arkansas, during the months of April and May 1980. The anomalous uranium appears to have originated from the Soviet satellite Cosmos-954, which fell over Canada on January 24, 1978. The uranium fallout occurred just about the time Mount St.

Y. Sakuragi; J. L. Meason; P. K. Kuroda

1983-01-01

139

OCCURRENCE OF URANIUM IN DIFFERENT ROCKS  

Microsoft Academic Search

A knowlodge of the conditions of the formation of uranium deposits ; depends on a knowledge of the form of uranium in rocks. The latest researches ; indicate that many different uranium minerals are formed (oxides, hydroxides, ; sulfates, carbonates, silicates, phosphates, arsenates, vanadates, etc.). ; Because of isomorphous mixtures uranium enters the crystal lattice of nonuranium ; minerals. In

Gerasimovskiy

1957-01-01

140

ANALYSIS OF URANIUM, THORIUM AND ZIRCONIUM  

Microsoft Academic Search

Considering the physico-chemical conditions for tributyl phosphate ; uranium extraction, the optimum nitrate concentration of the aqueous phase in ; which uranium separation by single extraction amounted virtually to 100% was ; determined. The extraction was carried out in tributyl phosphate--petrol ; solution and the uranium re-extracted in a dilute ammonium carbonate solution. ; The uranium content was determined by

Gy. Almassy; M. Ordogh; A. Schneer

1959-01-01

141

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Natural uranium. 540.309 Section 540.309 Money...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...General Definitions § 540.309 Natural uranium. The term natural uranium means...

2010-07-01

142

THE RECOVERY OF URANIUM FROM GAS MIXTURE  

Microsoft Academic Search

A method of separating uranium from a mixture of uranium hexafluoride ; and other gases is described that comprises bringing the mixture into contact ; with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride ; on the sulfate. The calcium sulfate is then leached with a selective solvent for ; the adsorbed uranium. (AEC)

Jury

1964-01-01

143

FISSION GAS YIELD IN URANIUM  

Microsoft Academic Search

The yield of xenon and krypton in irradiated uranium was found to vary ; with neutron flux from 4.8 cm³(STP)\\/cm³ uranium-atom percent burnup ; at 10¹² neut\\/cm²-sec to neut\\/cm²-sec as a result of neutron ; capture by the unstable isotopes Xe¹³³ and Xe¹³⁵. These results are ; applicable only to uranium irradiated in a thermal flux The fission gas yields

1962-01-01

144

Uranium removal from soils: An overview from the Uranium in Soils Integrated Demonstration program.  

National Technical Information Service (NTIS)

An integrated approach to remove uranium from uranium-contaminated soils is being conducted by four of the US Department of Energy national laboratories. In this approach, managed through the Uranium in Soils Integrated Demonstration program at the Fernal...

C. W. Francis, J. R. Brainard, D. A. York, D. J. Chaiko, G. Matthern

1994-01-01

145

Uranium hexafluoride bibliography  

SciTech Connect

This bibliography is a compilation of reports written about the transportation, handling, safety, and processing of uranium hexafluoride. An on-line literature search was executed using the DOE Energy files and the Nuclear Science Abstracts file to identify pertinent reports. The DOE Energy files contain unclassified information that is processed at the Office of Scientific and Technical Information of the US Department of Energy. The reports selected from these files were published between 1974 and 1983. Nuclear Science Abstracts contains unclassified international nuclear science and technology literature published from 1948 to 1976. In addition, scientific and technical reports published by the US Atomic Energy Commission and the US Energy Research and Development Administration, as well as those published by other agencies, universities, and industrial and research organizations, are included in the Nuclear Science Abstracts file. An alphabetical listing of the acronyms used to denote the corporate sponsors follows the bibliography.

Burnham, S.L.

1988-01-01

146

Preliminary Classification of Uranium Deposits.  

National Technical Information Service (NTIS)

For this classification, uranium deposits in sedimentary rocks are divided into two groups, syngenetic and epigenetic: syngenetic deposits are formed contemporaneously with deposition of the enclosing sediment; while epigenetic deposits are formed by prec...

D. G. Mickle

1978-01-01

147

Review of uranium bioassay techniques.  

National Technical Information Service (NTIS)

A variety of analytical techniques is available for evaluating uranium in excreta and tissues at levels appropriate for occupational exposure control and evaluation. A few (fluorometry, kinetic phosphorescence analysis, (alpha)-particle spectrometry, neut...

J. S. Bogard

1996-01-01

148

Laser induced phosphorescence uranium analysis  

DOEpatents

A method is described for measuring the uranium content of aqueous solutions wherein a uranyl phosphate complex is irradiated with a 5 nanosecond pulse of 425 nanometer laser light and resultant 520 nanometer emissions are observed for a period of 50 to 400 microseconds after the pulse. Plotting the natural logarithm of emission intensity as a function of time yields an intercept value which is proportional to uranium concentration.

Bushaw, Bruce A. (Kennewick, WA)

1986-01-01

149

Uranium and Radiation Education Outreach  

NSDL National Science Digital Library

This is an educational and public program designed to increase awareness of uranium health effects and environmental issues for students and community members that are impacted by uranium mining on the Navajo Nation. The site contains lesson plans, teaching resources and information about problem-based learning. There is also a paper on bridging indigenous and traditional scientific approaches as well as many useful links to additional resources.

Professionals, Northern A.

150

Rescuing a Treasure Uranium-233  

SciTech Connect

Uranium-233 (233U) is a synthetic isotope of uranium formed under reactor conditions during neutron capture by natural thorium (232Th). At high purities, this synthetic isotope serves as a crucial reference for accurately quantifying and characterizing natural uranium isotopes for domestic and international safeguards. Separated 233U is stored in vaults at Oak Ridge National Laboratory. These materials represent a broad spectrum of 233U from the standpoint isotopic purity the purest being crucial for precise analyses in safeguarding uranium. All 233U at ORNL currently is scheduled to be down blended with depleted uranium beginning in 2015. Such down blending will permanently destroy the potential value of pure 233U samples as certified reference material for use in uranium analyses. Furthermore, no replacement 233U stocks are expected to be produced in the future due to a lack of operating production capability and the high cost of returning to operation this currently shut down capability. This paper will describe the efforts to rescue the purest of the 233U materials arguably national treasures from their destruction by down blending.

Krichinsky, Alan M [ORNL; Goldberg, Dr. Steven A. [DOE SC - Chicago Office; Hutcheon, Dr. Ian D. [Lawrence Livermore National Laboratory (LLNL)

2011-01-01

151

Uranium favourability study in Nigeria  

NASA Astrophysics Data System (ADS)

Geological considerations indicate that four types of uranium deposits, three from within the crystalline rocks and the fourth from the sedimentary formations, can be explored for in Nigeria. The Precambrian Basement Complex underwent crustal reactivation in Pan-African times (600 150 Ma) during which migmatites and rocks of the Older Granite suite were emplaced. The occurrences of these rocks in northeastern, north-central and central Nigeria are possible hosts for the granitic type of uranium deposit. Vein-type uranium deposits are often localized in areas of the Basement Complex which have undergone intense brittle deformation. The high-level, anorogenic, peralkaline Younger Granites of Nigeria of Carboniferous to Cretaceous age have geochemical characteristics which are similar to those of the host rocks of non-orogenic type uranium deposit in alkali complexes such as the Bokan mountains of Alaska. The sandstone type of uranium deposit may be found in the Cretaceous-Recent continental sandstone formations in the Sokoto, Niger, Chad and Benue Basins of Nigeria and in the sediments overlying the Oban Massif in Cross Rivers State. Geologically similar sandstone occurrences elsewhere in the world (Gabon, Niger and Colorado, U.S.A.) are known to harbour important uranium mineralization.

Oshin, I. O.; Rahaman, M. A.

152

Investigation of the Uranium Solubility and Absorption  

NASA Astrophysics Data System (ADS)

Particles of uranium oxides were produced by combustion of depleted uranium (isotopic contents: 99.8% 238U, 0.2% 235U). Solubility of uranium oxides as well as solubility of metallic uranium in water of various pH values was investigated by x-ray spectroscopy. Also, eventual absorption of dissolved uranium oxides by plants from uranium contaminated ground was investigated. A thin uranium-oxide layer was spread on the soil planted with various vegetables. After a two-month vegetation period the uranium originated radioactivity in the vegetable samples were measured by x-ray spectroscopy and compared with the measurements of samples treated likewise, but in soil without addition of uranium. Due to low radioactivity of the vegetable samples, the spectra were analyzed using Bayesian inference, too.

Anicin, I.; Banjanac, R.; Dragic, A.; Jokovic, D.; Udovicic, V.

2005-01-01

153

ELECTROCHEMICAL STUDIES OF URANIUM METAL CORROSION MECHANISM AND KINETICS IN WATER  

SciTech Connect

During long-term underwater storage of low burn-up uranium metal fuel, a corrosion product sludge forms containing uranium metal grains1, uranium dioxide1,2, uranates1 and, in some cases, uranium peroxide1,3. Literature data on the corrosion of non-irradiated uranium metal and its alloys2,4 do not allow unequivocal prediction of the paragenesis of irradiated uranium in water. The goal of the present work conducted under the program CORROSION OF IRRADIATED URANIUM ALLOYS FUEL IN WATER is to study the corrosion of uranium and uranium alloys and the paragenesis of the corrosion products during long-term underwater storage of uranium alloy fuel irradiated at the Hanford Site. The elucidation of the physico-chemical nature of the corrosion of irradiated uranium alloys in comparison with non-irradiated uranium metal and its alloys is one of the most important aspects of this work. Electrochemical methods are being used to study uranium metal corrosion mechanism and kinetics. The present part of work aims to examine and revise, where appropriate, the understanding of uranium metal corrosion mechanism and kinetics in water.

Boudanova, Natalya; Maslennikov, Alexander; Peretroukhine, Vladimir F.; Delegard, Calvin H.

2006-10-01

154

Microbial accumulation of uranium, radium, and cesium  

SciTech Connect

Diverse microbial species varied considerably in their ability to accumulate uranium, cesium, and radium. Mechanistic differences in uranium uptake by Saccharomyces cerevisiae and Pseudomonas aeruginosa were indicated. S. serevisiae exhibited a slow (hours) surface accumulation of uranium which was subject to environmental factors, while P. aeruginosa accumulated uranium rapidly (minutes) as dense intracellular deposits and did not appear to be affected by environmental parameters. Metabolism was not required for uranium uptake by either organism. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several species tested.

Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; North, S.E.

1981-05-01

155

Atomistic properties of ? uranium.  

PubMed

The properties of the body-centered cubic ? phase of uranium (U) are calculated using atomistic simulations. First, a modified embedded-atom method interatomic potential is developed for the high temperature body-centered cubic (?) phase of U. This phase is stable only at high temperatures and is thus relatively inaccessible to first principles calculations and room temperature experiments. Using this potential, equilibrium volume and elastic constants are calculated at 0 K and found to be in close agreement with previous first principles calculations. Further, the melting point, heat capacity, enthalpy of fusion, thermal expansion and volume change upon melting are calculated and found to be in reasonable agreement with experiment. The low temperature mechanical instability of ? U is correctly predicted and investigated as a function of pressure. The mechanical instability is suppressed at pressures greater than 17.2 GPa. The vacancy formation energy is analyzed as a function of pressure and shows a linear trend, allowing for the calculation of the extrapolated zero pressure vacancy formation energy. Finally, the self-defect formation energy is analyzed as a function of temperature. This is the first atomistic calculation of ? U properties above 0 K with interatomic potentials. PMID:22293061

Beeler, Benjamin; Deo, Chaitanya; Baskes, Michael; Okuniewski, Maria

2012-02-22

156

Phonon Anomalies in ?-Uranium  

NASA Astrophysics Data System (ADS)

The temperature dependence of the phonon spectra of ?- uranium has recently been measured by Manley et al.[1] using inelastic neutron scattering and inelastic x-ray scattering techniques. Although there is little evidence of any anharmonicity, the phonon shows some softening in the optic modes at the zone boundary. In a later publication [2], an extra mode was reported to form at high temperatures, which is incompatible with a structure composed of a monoclinic Bravais lattice with a two-atom basis. We investigate the effect that the f electron-phonon interaction has on the phonon spectrum and its role on the possible formation of a breathing mode of mixed electron and phonon character. [1] M. E. Manley, B. Fultz, R. J. McQueeney, C. M. Brown, W. L. Hults, J. L. Smith, D. J. Thoma, R. Osborn, and J. L. Robertson, Phys. Rev. Lett. 86 (2001), p3076. [2] M. E. Manley, M. Yethiraj, H. Sinn, H. M. Volz, A. Alatas, J. C. Lashley, W. L. Hults, G. H. Lander, and J. L. Smith, Phys. Rev. Lett. 96 (2006), p125501.

Yang, Xiaodong; Riseborough, Peter

2007-03-01

157

Uranium Oxide Aerosol Transport in Porous Graphite  

SciTech Connect

The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactors lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

2012-01-23

158

Physical characteristics and solubility of long-lived airborne particulates in uranium producing and manufacturing facilities. A report upon completion of Phase I of the study.  

National Technical Information Service (NTIS)

The rates of dissolution in simulated lung fluid of uranium-238, thorium-230, radium-226, and lead-210 from a uranium ore matrix and of uranium-238 only from a uranium dioxide matrix have been studied. Changes in solubility rates accompanying changes in l...

R. Robertson S. Jones

1988-01-01

159

Maintaining the Uranium Resources Assessment Data System and assessing the 1990 US uranium potential resources  

Microsoft Academic Search

The Energy Information Administration's (EIA) Uranium Resource Assessment Data System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the Uranium Resource Assessment Data (URAD) System, (2) to assess the 1990 US uranium potential resources in various cost categories, and

R. B. McCammon; W. I. Finch; W. D. Grundy; C. T. Pierson

1991-01-01

160

??????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????? Comparative Core Analysis of TRIGA Reactor Using Virgin Uranium and Reprocesssing Uranium as Nuclear Fuel  

Microsoft Academic Search

The 10 MW TRIGA Reactor is a reactor using the UZrH fuel with 45 wt % of uranium in UZrH, 19.7 % enrichment. Both of virgin uranium and reprocessed uranium can be used as nuclear fuel for TRIGA reactor. The comparative of TRIGA core using both types of uranium were analyzed. From details on dimensions and compositions of the major

Chatchai Pawong; Sunanta Patrashakorn; Teerasak Veerapasapong

161

Uranium in soils integrated demonstration: 1992 update.  

National Technical Information Service (NTIS)

The Uranium in Soils Integrated Demonstration (ID) was initiated in 1991. The Fernald Environmental Management Project (FEMP), previously known as the Feed Materials Production Center (FMPC), was selected as the host site for the Uranium in Soils ID. The ...

K. R. Nuhfer

1992-01-01

162

Uranium soils integrated demonstration, 1993 status.  

National Technical Information Service (NTIS)

The Fernald Environmental Management Project (FEMP), operated by the Fernald Environmental Restoration Management Corporation (FERMCO) for the DOE, was selected as the host site for the Uranium Soils Integrated Demonstration. The Uranium Soils ID was esta...

K. Nuhfer

1994-01-01

163

Rescuing a Treasure-Uranium-233.  

National Technical Information Service (NTIS)

Uranium-233 (233U) is a synthetic isotope of uranium formed under reactor conditions during neutron capture by natural thorium (232Th). At high purities, this synthetic isotope serves as a crucial reference for accurately quantifying and characterizing na...

A. M. Krichinsky I. D. Hutcheon S. A. Goldberg

2011-01-01

164

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2013 CFR

...ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium enrichment means the process of increasing the concentration of the isotope U235 relative to that of the isotope...

2013-07-01

165

Oak Ridge Uranium Market Model (for Microcomputers).  

National Technical Information Service (NTIS)

The Oak Ridge Uranium Market Model (ORUMM) projects prices, production, imports, inventory, capital expenditures, and employment in the uranium mining and milling industry. The model considers every major production center and utility on a worldwide basis...

1991-01-01

166

National Uranium Resource Evaluation: Laredo Quadrangle, Texas.  

National Technical Information Service (NTIS)

The Laredo Quadrangle, Texas, was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for the occurrence of uranium deposits. The areas were delineated in accordance with criteria established by the National Uranium Resou...

A. J. Cherepon, A. J. Stauber

1982-01-01

167

Western Canada's Geological Promise in Uranium.  

National Technical Information Service (NTIS)

Uranium reserves in Saskatchewan are contained in unconformity-type deposits at the base of the Athabasca sandstone. In 1980 this region accounted for about 70 percent of all surface diamond drilling in Canada. Saskatchewan's share of Canadian uranium res...

L. S. Beck

1982-01-01

168

77 FR 14837 - Bioassay at Uranium Mills  

Federal Register 2010, 2011, 2012, 2013

...REGULATORY COMMISSION [NRC-2012-0057] Bioassay at Uranium Mills AGENCY: Nuclear Regulatory...regulatory guide (DG), DG-8051, ``Bioassay at Uranium Mills.'' This guide describes a bioassay program acceptable to the NRC staff...

2012-03-13

169

Biomonitoring of uranium and heavy metal pollution.  

National Technical Information Service (NTIS)

We examined various enzyme activity changes by intraperitoneal injection uranium. Cathepsin D was purified and characterized in the carp liver. Changes in these enzyme activity can be used as biochemical indicator of internal exposure of uranium. Lysosoma...

K. S. Lee K. J. Chun K. C. Kim J. G. Kim S. B. Kim

1992-01-01

170

Separation of Uranium Isotopes by Gas Centrifugation.  

National Technical Information Service (NTIS)

The uranium isotope enrichment is studied by means of the countercurrent gas centrifuge driven by thermal convection. A description is given of (a) the transfer and purification of the uranium hexafluoride used as process gas in the present investigation;...

I. Jordan

1980-01-01

171

Dissolution of metallic uranium and its alloys  

Microsoft Academic Search

This review focuses on dissolution\\/reaction systems capable of treating uranium metal waste to remove its pyrophoric properties.\\u000a The primary emphasis is the review of literature describing analytical and production-scale dissolution methods applied to\\u000a either uranium metal or uranium alloys. A brief summary of uranium's corrosion behavior is included since the corrosion resistance\\u000a of metals and alloys affects their dissolution behavior.

C. A. Laue; D. Gates-Anderson; T. E. Fitch

2004-01-01

172

Statistical data of the uranium industry  

SciTech Connect

Data are presented on US uranium reserves, potential resources, exploration, mining, drilling, milling, and other activities of the uranium industry through 1980. The compendium reflects the basic programs of the Grand Junction Office. Statistics are based primarily on information provided by the uranium exploration, mining, and milling companies. Data on commercial U/sub 3/O/sub 8/ sales and purchases are included. Data on non-US uranium production and resources are presented in the appendix. (DMC)

none,

1981-01-01

173

Advanced Proliferation Resistant, Lower Cost, Uranium-Thorium Dioxide Fuels for Light Water Reactors (Progress report for work through June 2002, 12th quarterly report)  

SciTech Connect

The overall objective of this NERI project is to evaluate the potential advantages and disadvantages of an optimized thorium-uranium dioxide (ThO2/UO2) fuel design for light water reactors (LWRs). The project is led by the Idaho National Engineering and Environmental Laboratory (INEEL), with the collaboration of three universities, the University of Florida, Massachusetts Institute of Technology (MIT), and Purdue University; Argonne National Laboratory; and all of the Pressurized Water Reactor (PWR) fuel vendors in the United States (Framatome, Siemens, and Westinghouse). In addition, a number of researchers at the Korean Atomic Energy Research Institute and Professor Kwangheon Park at Kyunghee University are active collaborators with Korean Ministry of Science and Technology funding. The project has been organized into five tasks: Task 1 consists of fuel cycle neutronics and economics analysis to determine the economic viability of various ThO2/UO2 fuel designs in PWRs, Task 2 will determine whether or not ThO2/UO2 fuel can be manufactured economically, Task 3 will evaluate the behavior of ThO2/UO2 fuel during normal, off-normal, and accident conditions and compare the results with the results of previous UO2 fuel evaluations and U.S. Nuclear Regulatory Commission (NRC) licensing standards, Task 4 will determine the long-term stability of ThO2/UO2 high-level waste, and Task 5 consists of the Korean work on core design, fuel performance analysis, and xenon diffusivity measurements.

Mac Donald, Philip Elsworth

2002-09-01

174

Y-12 Uranium Exposure Study  

SciTech Connect

Following the recent restart of operations at the Y-12 Plant, the Radiological Control Organization (RCO) observed that the enriched uranium exposures appeared to involve insoluble rather than soluble uranium that presumably characterized most earlier Y-12 operations. These observations necessitated changes in the bioassay program, particularly the need for routine fecal sampling. In addition, it was not reasonable to interpret the bioassay data using metabolic parameter values established during earlier Y-12 operations. Thus, the recent urinary and fecal bioassay data were interpreted using the default guidance in Publication 54 of the International Commission on Radiological Protection (ICRP); that is, inhalation of Class Y uranium with an activity median aerodynamic diameter (AMAD) of 1 {micro}m. Faced with apparently new workplace conditions, these actions were appropriate and ensured a cautionary approach to worker protection. As additional bioassay data were accumulated, it became apparent that the data were not consistent with Publication 54. Therefore, this study was undertaken to examine the situation.

Eckerman, K.F.; Kerr, G.D.

1999-08-05

175

PENECONCORDANT URANIUM DEPOSIT-A PROPOSED TERM  

Microsoft Academic Search

Peneconcordant uranium deposits cover a widespread and important type of ; uranium deposits that have a common and distinctive form, namely, nearly ; concordant to the bedding of the host rock. The term describes the form of the ; numerous and highly productive uranium deposits in sedimentary rocks of the ; Colorado Plateau, Wyoming, North and South Dakota, and Texas.

W. I. Finch

1959-01-01

176

Predicting 232U Content in Uranium  

Microsoft Academic Search

The minor isotope 232U may ultimately be used for detection or confirmation of uranium in a variety of applications. The primary advantage of 232 U as an indicator of the presence of enriched uranium is the plentiful and penetrating nature of the radiation emitted by its daughter radionuclide 208Tl. A possible drawback to measuring uranium via 232U is the relatively

AJ Peurrung

1999-01-01

177

Profile of World Uranium Enrichment Programs - 2007  

Microsoft Academic Search

It is generally agreed that the most difficult step in building a nuclear weapon is acquiring weapons grade fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, while HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium

Laughter; Mark D

2007-01-01

178

Profile of World Uranium Enrichment Programs-2009  

Microsoft Academic Search

It is generally agreed that the most difficult step in building a nuclear weapon is acquiring fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, whereas HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium (LEU) for

Laughter; Mark D

2009-01-01

179

Bioremediation of uranium contaminated soils and wastes  

Microsoft Academic Search

Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (1) stabilization of uranium and toxic metals with reduction

1998-01-01

180

BIOREMEDIATION OF URANIUM CONTAMINATED SOILS AND WASTES  

Microsoft Academic Search

Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (i) stabilization of uranium and toxic metals with reduction

1998-01-01

181

High strength uranium-tungsten alloy process  

DOEpatents

Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

Dunn, Paul S. (Santa Fe, NM); Sheinberg, Haskell (Los Alamos, NM); Hogan, Billy M. (Los Alamos, NM); Lewis, Homer D. (Bayfield, CO); Dickinson, James M. (Los Alamos, NM)

1990-01-01

182

High strength uranium-tungsten alloys  

DOEpatents

Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

Dunn, Paul S. (Santa Fe, NM); Sheinberg, Haskell (Los Alamos, NM); Hogan, Billy M. (Los Alamos, NM); Lewis, Homer D. (Bayfield, CO); Dickinson, James M. (Los Alamos, NM)

1991-01-01

183

SUGGESTED URINARY TOLERANCE LEVELS FOR ENRICHED URANIUM  

Microsoft Academic Search

The animal experimentation basis for estimates of permissible levels of ; airborne, soluble, and insoluble natural uranium is briefly reviewed. It ; suggested that permissibie air and urinary levels for enriched uranium be set at ; values equivalent to those for natural uranium in terms of disintegrations per ; minute per unit volume. An attempt is made to calculate the

Hursh

1957-01-01

184

Uranium Miner Lung Cancer Study. Final Report.  

National Technical Information Service (NTIS)

This study on uranium miners was started in 1957 and extended through June 30, 1986. It consisted of the routine screening of sputum from uranium miners of the Colorado Plateau, and collection of surgical and autopsy material from uranium miners who devel...

G. Saccomanno

1986-01-01

185

Uranium mill tailings and radon  

SciTech Connect

The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the US may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action Program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100.

Hanchey, L A

1981-01-01

186

Uranium mill tailings and radon  

SciTech Connect

The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the United States may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100.

Hanchey, L A

1981-04-01

187

Uranium spectra in the ICP  

NASA Astrophysics Data System (ADS)

Uranium spectra have been studied by inductively coupled plasma atomic emission spectroscopy (ICP-AES). In total, 8361 uranium lines were observed in the wavelength range of 235-500 nm. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with data files and text files for an IBM-compatible computer. The main article discusses the scientific aspects of the subject and explains the purpose of the data files.

Ghazi, A. A.; Qamar, Sajid; Atta, M. A.

1994-05-01

188

Measurement of uranium enrichment for gaseous uranium at low pressure  

SciTech Connect

X-ray fluoresence determines the amount of total uranium present in gaseous UF/sub 6/ inside cascade header pipes of a uranium centrifuge enrichment facility. A highly collimated source, highly collimated detector, and a very rigid, reproducible geometry are required. Two measurements of the 185.7-keV gamma ray from /sup 235/U using two collimators determine the amount of /sup 235/U present only in the gas phase. The ratio of the gas-only /sup 235/U signal to the total uranium gas-only signal is directly proportional to the enrichment of the process UF/sub 6/ gas. This measurement technique is independent of the deposit that forms on a surface in contact with UF/sub 6/. This measurement technique is independent of the pressure of the gaseous UF/sub 6/. This technique has the required sensitivity to determine whether the process gas is of uranium enrichment less than or equal to 20% or >20%. 6 refs., 4 figs., 4 tabs.

Close, D.A.; Pratt, J.C.; Atwater, H.F.; Malanify, J.J.; Nixon, K.V.; Speir, L.G.

1985-01-01

189

NUSIMEP-7: uranium isotope amount ratios in uranium particles.  

PubMed

The Institute for Reference Materials and Measurements (IRMM) has extensive experience in the development of isotopic reference materials and the organization of interlaboratory comparisons (ILC) for nuclear measurements in compliance with the respective international guidelines (ISO Guide 34:2009 and ISO/IEC 17043:2010). The IRMM Nuclear Signatures Interlaboratory Measurement Evaluation Program (NUSIMEP) is an external quality control program with the objective of providing materials for measurements of trace amounts of nuclear materials in environmental matrices. Measurements of the isotopic ratios of the elements uranium and plutonium in small amounts, typical of those found in environmental samples, are required for nuclear safeguards and security, for the control of environmental contamination and for the detection of nuclear proliferation. The measurement results of participants in NUSIMEP are evaluated according to international guidelines in comparison to independent external certified reference values with demonstrated metrological traceability and uncertainty. NUSIMEP-7 focused on measurements of uranium isotope amount ratios in uranium particles aiming to support European Safeguards Directorate General for Energy (DG ENER), the International Atomic Energy Agency's (IAEA) network of analytical laboratories for environmental sampling (NWAL) and laboratories in the field of particle analysis. Each participant was provided two certified test samples: one with single and one with double isotopic enrichment. These NUSIMEP test samples were prepared by controlled hydrolysis of certified uranium hexafluoride in a specially designed aerosol deposition chamber at IRMM. Laboratories participating in NUSIMEP-7 received the test samples of uranium particles on two graphite disks with undisclosed isotopic ratio values n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U). The uranium isotope ratios had to be measured using their routine analytical procedures. Measurement of the major ratio n((235)U)/n((238)U) was obligatory; measurement of the minor ratios n((234)U)/n((238)U) and n((236)U)/n((238)U) was optional. Of the twenty-four institutes that registered for NUSIMEP-7, 17 have reported their results achieved by different analytical methods. The results of NUSIMEP-7 confirm the capability of laboratories in measuring n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U) in uranium particles of the size below 1 ?m diameter. Furthermore, they underpin the recent advances in instrumental techniques in the field of particle analysis. In addition, feedback from the measurement communities from nuclear safeguards, nuclear security and earth sciences was collected in view of identifying future needs for NUSIMEP interlaboratory comparisons. PMID:23548475

Truyens, J; Stefaniak, E A; Aregbe, Y

2013-11-01

190

Reactions of plutonium dioxide with water and oxygen-hydrogen mixtures: Mechanisms for corrosion of uranium and plutonium.  

National Technical Information Service (NTIS)

Investigation of the interactions of plutonium dioxide with water vapor and with an oxygen-hydrogen mixture show that the oxide is both chemically reactive and catalytically active. Correspondence of the chemical behavior with that for oxidation of uraniu...

J. M. Haschke T. H. Allen L. A. Morales

1999-01-01

191

Removal of uranium from aqueous HF solutions  

DOEpatents

This invention is a simple and effective method for removing uranium from aqueous HF solutions containing trace quantities of the same. The method comprises contacting the solution with particulate calcium fluoride to form uranium-bearing particulates, permitting the particulates to settle, and separting the solution from the settled particulates. The CaF.sub.2 is selected to have a nitrogen surface area in a selected range and is employed in an amount providing a calcium fluoride/uranium weight ratio in a selected range. As applied to dilute HF solutions containing 120 ppm uranium, the method removes at least 92% of the uranium, without introducing contaminants to the product solution.

Pulley, Howard (West Paducah, KY) [West Paducah, KY; Seltzer, Steven F. (Paducah, KY) [Paducah, KY

1980-01-01

192

Process for alloying uranium and niobium  

DOEpatents

Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uraniun sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

Holcombe, Cressie E. (Farragut, TN); Northcutt, Jr., Walter G. (Oak Ridge, TN); Masters, David R. (Knoxville, TN); Chapman, Lloyd R. (Knoxville, TN)

1991-01-01

193

Radiation Exposure of Uranium Miners.  

National Technical Information Service (NTIS)

Increasing attention has been given, within recent years, to observations that extended exposure in some uranium mines is associated with an increase in lung cancer. Upon approval by the Federal Radiation Council (FRC), its staff carried out a study on th...

C. L. Comar

1968-01-01

194

Uranium Extraction from Phosphoric Acid.  

National Technical Information Service (NTIS)

A study has been carried out for the extraction of uranium from phosphoric acid produced in Algeria. First of all, the Algerian phosphoric acid produced by SONATRACH has been characterised. This study helped the authors to synthesize a phosphoric acid tha...

A. Lounis

1983-01-01

195

Uranium: Prices, rise, then fall  

SciTech Connect

Uranium prices hit eight-year highs in both market tiers, $16.60/lb U{sub 3}O{sub 8} for non-former Soviet Union (FSU) origin and $15.50 for FSU origin during mid 1996. However, they declined to $14.70 and $13.90, respectively, by the end of the year. Increased uranium prices continue to encourage new production and restarts of production facilities presently on standby. Australia scrapped its {open_quotes}three-mine{close_quotes} policy following the ouster of the Labor party in a March election. The move opens the way for increasing competition with Canada`s low-cost producers. Other events in the industry during 1996 that have current or potential impacts on the market include: approval of legislation outlining the ground rules for privatization of the US Enrichment Corp. (USEC) and the subsequent sales of converted Russian highly enriched uranium (HEU) from its nuclear weapons program, announcement of sales plans for converted US HEU and other surplus material through either the Department of Energy or USEC, and continuation of quotas for uranium from the FSU in the United States and Europe. In Canada, permitting activities continued on the Cigar Lake and McArthur River projects; and construction commenced on the McClean Lake mill.

Pool, T.C.

1997-03-01

196

Enriched uranium recovery flowsheet improvements  

SciTech Connect

Savannah River uses 7.5% TBP to recover and purify enriched uranium. Adequate decontamination from fission products is necessary to reduce personnel exposure and to ensure that the enriched uranium product meets specifications. Initial decontamination of the enriched uranium from the fission products is carried out in the 1A bank, 16 stages of mixer-settlers. Separation of the enriched uranium from the fission product, /sup 95/Zr, has been adequate, but excessive solvent degradation caused by the long phase contact times in the mixer-settlers has limited the /sup 95/Zr decontamination factor (DF). An experimental program is investigating the replacement of the current 1A bank with either centrifugal contactors or a combination of centrifugal contactors and mixer-settlers. Experimental work completed has compared laboratory-scale centrifugal contactors and mixer-settlers for /sup 95/Zr removal efficiencies. Feed solutions spiked with actual plant solutions were used. The /sup 95/Zr DF was significantly better in the mixer-settlers than in the centrifugal contactors. As a result of this experimental study, a hybrid equipment flowsheet has been proposed for plant use. The hybrid equipment flowsheet combines the advantages of both types of solvent extraction equipment. Centrifugal contactors would be utilized in the extraction and initial scrub sections, followed by additional scrub stages of mixer-settlers.

Holt, D L

1986-01-01

197

DETERMINATION OF FLUORINE IN URANIUM  

Microsoft Academic Search

A tentative method for the determination of fluorine in uranium turnings ; has been devised. The most suitable method for dissolving the metal for this ; purpose is by using a mixure of perchloric acid and hydrogen peroxide. The ; titration of fluorine with thorium nitrate using chrome azurol S as indicator ; presents no difficulty to the average operator.

A. B. Crowther; O. Stokoe; W. J. Gray; W. J. McCreath

1951-01-01

198

Uranium Mill Tailings and Radon.  

National Technical Information Service (NTIS)

The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is e...

L. A. Hanchey

1981-01-01

199

Literature information applicable to the reaction of uranium oxides with chlorine to prepare uranium tetrachloride  

SciTech Connect

The reaction of uranium oxides and chlorine to prepare anhydrous uranium tetrachloride (UCl{sub 4}) are important to more economical preparation of uranium metal. The most practical reactions require carbon or carbon monoxide (CO) to give CO or carbon dioxide (CO{sub 2}) as waste gases. The chemistry of U-O-Cl compounds is very complex with valances of 3, 4, 5, and 6 and with stable oxychlorides. Literature was reviewed to collect thermochemical data, phase equilibrium information, and results of experimental studies. Calculations using thermodynamic data can identify the probable reactions, but the results are uncertain. All the U-O-Cl compounds have large free energies of formation and the calculations give uncertain small differences of large numbers. The phase diagram for UCl{sub 4}-UO{sub 2} shows a reaction to form uranium oxychloride (UOCl{sub 2}) that has a good solubility in molten UCl{sub 4}. This appears more favorable to good rates of reaction than reaction of solids and gases. There is limited information on U-O-Cl salt properties. Information on the preparation of titanium, zirconium, silicon, and thorium tetrachlorides (TiCl{sub 4}, ZrCl{sub 4}, SiCl{sub 4}, ThCl{sub 4}) by reaction of oxides with chlorine (Cl{sub 2}) and carbon has application to the preparation of UCl{sub 4}.

Haas, P.A.

1992-02-01

200

Uranium Immobilization in Wetland Soils  

NASA Astrophysics Data System (ADS)

In wetlands, which are a major feature at the groundwater-surface water interface, plants deliver oxygen to the subsurface to keep root tissue aerobic. Some of this oxygen leaches into the rhizosphere where it will oxidize iron that typically precipitates on or near roots. Furthermore, plans provide carbon via root exudates and turnover, which in the presence of the iron oxides drives the activity of heterotrophic iron reducers in wetland soils. Oxidized iron is an important electron acceptor for many microbially-driven transformations, which can affect the fate and transport of several pollutants. It has been shown that heterotrophic iron reducing organisms, such as Geobacter sp., can reduce water soluble U(VI) to insoluble U(IV). The goal of this study was to determine if and how iron cycling in the wetland rhizosphere affects uranium dynamics. For this purpose, we operated a series of small-scale wetland mesocosms in a greenhouse to simulate the discharge of uranium-contaminated groundwater to surface waters. The mesocosms were operated with two different Fe(II) loading rates, two plant types, and unplanted controls. The mesocosms contained zones of root exclusion to differentiate between the direct presence and absence of roots in the planted mesocosms. The mesocosms were operated for several month to get fully established, after which a U(VI) solution was fed for 80 days. The mesocosms were then sacrificed and analyzed for solid-associated chemical species, microbiological characterization, micro-X-ray florescence (-XRF) mapping of Fe and U on the root surface, and U speciation via X-ray Absorption Near Edge Structure (XANES). Results showed that bacterial numbers including Geobacter sp., Fe(III), as well as total uranium, were highest on roots, followed by sediments near roots, and lowest in zones without much root influence. Results from the -XRF mapping on root surfaces indicated a strong spatial correlation between Fe and U. This correlation was stronger for the mesocosms with the higher Fe(II) load. Analysis via XANES showed that a fraction (up to ~1/3) of uranium was reduced to U(IV), for mesocosms operated under low iron loading, indicating that iron cycling in the rhizosphere also results in uranium reduction and immobilization. For mesocosms operating under the higher iron loading, the fraction of uranium immobilized as U(IV) was much lower, indicating that uranium co-precipitation with iron might have been the dominant immobilization process. In parallel to these mesocosm experiments, dialysis samplers have been deployed at the Savannah River National Laboratory near a creek with uranium contamination, to determine dissolved species, including Fe(II) and U(VI) in these wetland soils and their seasonal variability. The results show that there is a strong seasonal variability in dissolved iron and uranium, indicating a strong immobilization during the growing season, which is consistent with the mesocosm experimental results that the rhizosphere iron and uranium cycling are closely linked.

Jaffe, Peter R.; Koster van Groos, Paul G.; Li, Dien; Chang, Hyun-Shik; Seaman, John C.; Kaplan, Daniel I.; Peacock, Aaron D.; Scheckel, Kirk

2014-05-01

201

Summary of an interlaboratory comparison program on the analysis of pyrocarbon- and silicon carbide-coated uranium--thorium carbide beads  

SciTech Connect

Annual progress report for the period July 1972 through June NBL conducted an interlaboratory comparison program on the analysis of pyrocarbon- and silicon carbide-coated uranium-thorium carbide nuclear fuel beads. Samples of the beads from a single production lot, and synthetic uranium dioxide-- thorium dioxide mixtures were analyzed for uranium by 3 laboratories by nondestructive assay techniques, and for uranium and thorium by 7 laboratories by destructive chemical procedures. (auth)

Bingham, C.D.; Whichard, J.

1973-09-01

202

Inherently safe in situ uranium recovery.  

SciTech Connect

Expansion of uranium mining in the United States is a concern to some environmental groups and sovereign Native American Nations. An approach which may alleviate some problems is to develop inherently safe in situ uranium recovery ('ISR') technologies. Current ISR technology relies on chemical extraction of trace levels of uranium from aquifers that, once mined, can still contain dissolved uranium and other trace metals that are a health concern. Existing ISR operations are few in number; however, high uranium prices are driving the industry to consider expanding operations nation-wide. Environmental concerns and enforcement of the new 30 ppb uranium drinking water standard may make opening new mining operations more difficult and costly. Here we propose a technological fix: the development of inherently safe in situ recovery (ISISR) methods. The four central features of an ISISR approach are: (1) New 'green' leachants that break down predictably in the subsurface, leaving uranium, and associated trace metals, in an immobile form; (2) Post-leachant uranium/metals-immobilizing washes that provide a backup decontamination process; (3) An optimized well-field design that increases uranium recovery efficiency and minimizes excursions of contaminated water; and (4) A combined hydrologic/geochemical protocol for designing low-cost post-extraction long-term monitoring. ISISR would bring larger amounts of uranium to the surface, leave fewer toxic metals in the aquifer, and cost less to monitor safely - thus providing a 'win-win-win' solution to all stakeholders.

Krumhansl, James Lee; Beauheim, Richard Louis; Brady, Patrick Vane; Arnold, Bill Walter; Kanney, Joseph F.; McKenna, Sean Andrew

2009-05-01

203

Renal effects of uranium in drinking water.  

PubMed Central

Animal studies and small studies in humans have shown that uranium is nephrotoxic. However, more information about its renal effects in humans following chronic exposure through drinking water is required. We measured uranium concentrations in drinking water and urine in 325 persons who had used drilled wells for drinking water. We measured urine and serum concentrations of calcium, phosphate, glucose, albumin, creatinine, and beta-2-microglobulin to evaluate possible renal effects. The median uranium concentration in drinking water was 28 microg/L (interquartile range 6-135, max. 1,920 microg/L) and in urine 13 ng/mmol creatinine (2-75), resulting in the median daily uranium intake of 39 microg (7-224). Uranium concentration in urine was statistically significantly associated with increased fractional excretion of calcium and phosphate. Increase of uranium in urine by 1 microg/mmol creatinine increased fractional excretion of calcium by 1.5% [95% confidence interval (CI), 0.6-2.3], phosphate by 13% (1.4-25), and glucose excretion by 0.7 micromol/min (-0.4-1.8). Uranium concentrations in drinking water and daily intake of uranium were statistically significantly associated with calcium fractional excretion, but not with phosphate or glucose excretion. Uranium exposure was not associated with creatinine clearance or urinary albumin, which reflect glomerular function. In conclusion, uranium exposure is weakly associated with altered proximal tubulus function without a clear threshold, which suggests that even low uranium concentrations in drinking water can cause nephrotoxic effects. Despite chronic intake of water with high uranium concentration, we observed no effect on glomerular function. The clinical and public health relevance of the findings are not easily established, but our results suggest that the safe concentration of uranium in drinking water may be within the range of the proposed guideline values of 2-30 microg/L.

Kurttio, Paivi; Auvinen, Anssi; Salonen, Laina; Saha, Heikki; Pekkanen, Juha; Makelainen, Ilona; Vaisanen, Sari B; Penttila, Ilkka M; Komulainen, Hannu

2002-01-01

204

Analytical laboratories method No. 4018 - uranium isolation and purification from various matrices for subsequent uranium isotopic analysis  

SciTech Connect

This sample preparation method is designed to purify and isolate measurable quantities of uranium from varying quantities of other elements. The purified uranium is used for subsequent uranium isotope analysis. Steps are included for the purification of uranium from most commonly encountered uranium matrices. Purifications normally require 2 to 6 hours, depending on sample matrix.

Not Available

1987-02-26

205

Diffusive gradient in thin FILMS (DGT) compared with soil solution and labile uranium fraction for predicting uranium bioavailability to ryegrass  

Microsoft Academic Search

The usefulness of uranium concentration in soil solution or recovered by selective extraction as unequivocal bioavailability indices for uranium uptake by plants is still unclear. The aim of the present study was to test if the uranium concentration measured by the diffusive gradient in thin films (DGT) technique is a relevant substitute for plant uranium availability in comparison to uranium

L. Duqune; H. Vandenhove; F. Tack; M. Van Hees; J. Wannijn

2010-01-01

206

Precipitation of uranium peroxide from the leach liquor of uranium ores.  

National Technical Information Service (NTIS)

A chemical precipitation process of recovering uranium from the leach liquor of uranium ores was investigated. The process primarily includes the precipitation of iron with lime, the preprocessing of the slurry of iron hydroxides and the precipitation of ...

Gao Xizhen Lin Sirong Guo Erhua Lu Shijie

1995-01-01

207

Measurement of Trace Uranium Isotopes  

SciTech Connect

The extent to which thermal ionization mass spectrometry (TIMS) can measure trace quantities of 233U and 236U in the presence of a huge excess of natural uranium is evaluated. This is an important nuclear non-proliferation measurement. Four ion production methods were evaluated with three mass spectrometer combinations. The most favorable combinations are not limited by abundance sensitivity; rather, the limitations are the ability to generate a uranium ion beam of sufficient intensity to obtain the required number of counts on the minor isotopes in relationship to detector background. The most favorable situations can measure isotope ratios in the range of E10 if sufficient sample intensity is available. These are the triple sector mass spectrometer with porous ion emitters (PIE) and the single sector mass spectrometer with energy filtering.

Matthew G. Watrous; James E. Delmore

2011-05-01

208

Uranium and plutonium isotopes in the atmosphere  

SciTech Connect

Uranium 234 and 235 were found to be highly enriched relative to uranium 238 in several rain samples collected at Fayetteville, Arkansas, during the months of April and May 1980. The anomalous uranium appears to have originated from the Soviet satellite Cosmos-954, which fell over Canada on January 24, 1978. The uranium fallout occurred just about the time Mount St. Helens erupted on May 18, 1980. The concentration of /sup 238/U in rain increased markedly after the eruption of Mount St. Helens, and it appeared as if a large quantity of natural uranium was injected into the atmosphere by the volcanic eruption. The pattern of variation of the concentrations of uranium in rain after the eruption of Mount St. Helens was found to be similar to that of plutonium isotopes.

Sakuragi, Y.; Meason, J.L.; Kuroda, P.K.

1983-04-20

209

Uranium and plutonium isotopes in the atmosphere  

NASA Astrophysics Data System (ADS)

Uranium 234 and 235 were found to be highly enriched relative to uranium 238 in several rain samples collected at Fayetteville, Arkansas, during the months of April and May 1980. The anomalous uranium appears to have originated from the Soviet satellite Cosmos-954, which fell over Canada on January 24, 1978. The uranium fallout occurred just about the time Mount St. Helens erupted on May 18, 1980. The concentration of 238U in rain increased markedly after the eruption of Mount St. Helens, and it appeared as if a large quantity of natural uranium was injected into the atmosphere by the volcanic eruption. The pattern of variation of the concentrations of uranium in rain after the eruption of Mount St. Helens was found to be similar to that of plutonium isotopes.

Sakuragi, Y.; Meason, J. L.; Kuroda, P. K.

1983-04-01

210

Uranium Metal Analysis via Selective Dissolution  

SciTech Connect

Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation/corrosion in water. A thorough knowledge of the uranium metal concentration in sludge therefore is essential to successful sludge management and waste process design. The goal of this work was to establish a rapid routine analytical method to determine uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of up to 1000-fold higher total uranium concentrations (i.e., up to 30 wt% and more uranium) for samples to be taken during the upcoming sludge characterization campaign and in future analyses for sludge handling and processing. This report describes the experiments and results obtained in developing the selective dissolution technique to determine uranium metal concentration in K Basin sludge.

Delegard, Calvin H.; Sinkov, Sergey I.; Schmidt, Andrew J.; Chenault, Jeffrey W.

2008-09-10

211

Description of the Canadian particulate-fill waste-package (WP) system for spent-nuclear fuel (SNF) and its applicability to light-water reactor SNF WPs with depleted uranium-dioxide fill  

SciTech Connect

The US is beginning work on an advanced, light-water reactor (LWR), spent nuclear fuel (SNF), waste package (WP) that uses depleted uranium dioxide (UO{sub 2}) fill. The Canadian nuclear fuel waste management program has completed a 15-year development program of its repository concept for CANadian Deuterium Uranium (CANDU) reactor SNF. As one option, Canada has developed a WP that uses a glass-bead or silica-sand fill. The Canadian development work on fill materials inside WPs can provide a guide for the development of LWR SNF WPs using depleted uranium (DU) fill materials. This report summarizes the Canadian work, identifies similarities and differences between the Canadian design and the design being investigated in the US to use DU fill, and identifies what information is applicable to the development of a DU fill for LWR SNF WPs. In both concepts, empty WPs are loaded with SNF, the void space between the fuel pins and the outer void space between SNF assemblies and the inner WP wall would be filled with small particles, the WPs are then sealed, and the WPs are placed into the repository.

Forsberg, C.W.

1997-10-20

212

Luminescence of powdered uranium glasses  

NASA Technical Reports Server (NTRS)

Measurement of cathodoluminescence and photoluminescence efficiencies in powdered borosilicate glasses having different particle size and different uranium content. Excitation with 100 to 350 keV electrons and with 253.7 nm light was found to produce identical absolute radiant exitance spectra in powdered samples. The most efficient glass was one containing 29.4 wt% B2O3, 58.8 wt% SiO2, 9.8 wt% Na2O and 2.0 wt% UO2.

Eubanks, A. G.; Mcgarrity, J. M.; Silverman, J.

1974-01-01

213

Visualizing different uranium oxidation states during the surface alteration of uraninite and uranium tetrachloride  

Microsoft Academic Search

Low-temperature alteration reactions on uranium phases may lead to the mobilization of uranium and thereby poses a potential\\u000a threat to humans living close to uranium-contaminated sites. In this study, the surface alteration of uraninite (UO2) and uranium tetrachloride (UCl4) in air atmosphere was studied by confocal laser scanning microscopy (CLSM) and laser-induced fluorescence spectroscopy using\\u000a an excitation wavelength of 408nm.

Kay Grossmann; Thuro Arnold; Robin Steudtner; Stefan Weiss; Gert Bernhard

2009-01-01

214

Maintaining the Uranium Resources Assessment Data System and assessing the 1990 US uranium potential resources  

SciTech Connect

The Energy Information Administration's (EIA) Uranium Resource Assessment Data System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the Uranium Resource Assessment Data (URAD) System, (2) to assess the 1990 US uranium potential resources in various cost categories, and (3) to identify problems and to recommend changes that are needed to improve the URAD System. 13 refs., 5 figs., 4 tabs.

McCammon, R.B. (Geological Survey, Reston, VA (United States)); Finch, W.I.; Grundy, W.D.; Pierson, C.T. (Geological Survey, Denver, CO (United States))

1991-12-31

215

Uranium in the Earth's core  

NASA Astrophysics Data System (ADS)

That there is no radioactivity in the earth's core is a concept that has long been held. The reason is that the major radioactive elements, potassium and uranium, exist as siderophobic compounds, such as silicates and oxides, in the earth's mantle and thus were thought to be immiscible with the metal core. An experimental measurement of the binary system of steel and UO2, however, shows that above 3120 K the system is a two-phase liquid, the one rich in UO2 and the other poor in UO2. The phase diagram predicts that there must be a temperature above which there is total miscibility between UO2 and steel. This temperature may be above the boiling point of UO2, estimated as 3750 K. The temperature at the core-mantle interface of the earth's interior is estimated most recently as 3130 K. Thus there is a strong likelihood that uranium exists in the earth's metal core. Hence the natural alpha radioactivity of uranium offers a power source for the earth's magnetic dynamo.

Feber, Roy C.; Wallace, Terry C.; Libby, Leona Marshall

1984-04-01

216

Review of uranium bioassay techniques  

SciTech Connect

A variety of analytical techniques is available for evaluating uranium in excreta and tissues at levels appropriate for occupational exposure control and evaluation. A few (fluorometry, kinetic phosphorescence analysis, {alpha}-particle spectrometry, neutron irradiation techniques, and inductively-coupled plasma mass spectrometry) have also been demonstrated as capable of determining uranium in these materials at levels comparable to those which occur naturally. Sample preparation requirements and isotopic sensitivities vary widely among these techniques and should be considered carefully when choosing a method. This report discusses analytical techniques used for evaluating uranium in biological matrices (primarily urine) and limits of detection reported in the literature. No cost comparison is attempted, although references are cited which address cost. Techniques discussed include: {alpha}-particle spectrometry; liquid scintillation spectrometry, fluorometry, phosphorometry, neutron activation analysis, fission-track counting, UV-visible absorption spectrophotometry, resonance ionization mass spectrometry, and inductively-coupled plasma mass spectrometry. A summary table of reported limits of detection and of the more important experimental conditions associated with these reported limits is also provided.

Bogard, J.S.

1996-04-01

217

Uranium Production- ChemCases.com  

NSDL National Science Digital Library

Uranium is present in the Earths crust at an average concentration of 2 parts per million. Acidic rocks with high silicate, such as granite, have higher than average concentrations of uranium, while sedimentary and basic rocks have lower than average concentrations. Uranite or pitchblende (U3O8), the most common uranium-containing ores, are mixtures of UO2 (basic) and UO3 (amphoteric) oxides.

Settle, Frank

218

Uranium Content in the External Environment and Human Excreta.  

National Technical Information Service (NTIS)

Uranium migration from soil and water into animal and vegetable products was studied. A direct correlation between the amount of uranium in soil, water, and foodstuffs was found. Uranium accumulates in different proportions on the surface and inside veget...

A. V. Berdnikova

1964-01-01

219

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2013 CFR

...ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched uranium or HEU means uranium enriched to twenty (20) percent or greater in the isotope...

2013-07-01

220

31 CFR 540.315 - Uranium-235 (U235).  

Code of Federal Regulations, 2013 CFR

...TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.315 Uranium-235 (U235). The term uranium-235 or U235 means the fissile isotope found in natural...

2013-07-01

221

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2013 CFR

...AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.308 Low Enriched Uranium (LEU). The term low enriched uranium or LEU means uranium enriched to less than twenty (20) percent in the isotope...

2013-07-01

222

National Uranium Resource Evaluation: Lawton Quadrangle, Oklahoma and Texas.  

National Technical Information Service (NTIS)

Uranium resources of the Lawton Quadrangle, Oklahoma and Texas, were evaluated to a depth of 1500 m using National Uranium Resource Evaluation critieria. Five areas of uranium favorability were delineated. Diagenetically altered, quartzose and sublithic, ...

Z. Al-Shaieb R. G. Thomas G. F. Stewart

1982-01-01

223

National Uranium Resource Evaluation: Lamar Quadrangle, Colorado and Kansas.  

National Technical Information Service (NTIS)

Uranium resources of the Lamar Quadrangle, Colorado and Kansas, were evaluated using National Uranium Resource Evaluation criteria. The environment favorable for uranium is the Lower Cretaceous Dakota Sandstone in the area east of John Martin Reservoir fo...

A. M. Maarouf V. C. Johnson

1982-01-01

224

National Uranium Resource Evaluation, Tularosa Quadrangle, New Mexico.  

National Technical Information Service (NTIS)

Uranium favorability of the Tularosa Quadrangle, New Mexico, was evaluated to a depth of 1500 m using National Uranium Resource Evaluation criteria. Uranium occurrences reported in the literature were located, sampled, and described in detail. Areas of an...

V. P. Berry P. A. Nagy W. C. Spreng C. W. Barnes D. Smouse

1981-01-01

225

Uranium mill tailings quarterly report, January-March 1982  

Microsoft Academic Search

Progress is reported on: radon barrier systems for uranium mill tailings; liner evaluation for uranium mill tailings; revegetation\\/rock cover for stabilization of inactive U-tailings sites; and application of long-term chemical biobarriers for uranium tailings.

Latkovich

1982-01-01

226

INTERNAL DISTRIBUTION OF URANIUM COMPOUNDS IN THE BODY AND ACUTE URANIUM POISONING. (English Text)  

Microsoft Academic Search

Uranium in animals was measured by counting the betarays emitted. ; Uranium concentration in the blood was maximum 6 hours after injection, and then ; gradually decreased. Deposition in the liver. spleen, adrenal glands, and ; muscles paralleled the blood level. In the kidneys, however, uranium ; fragmentation gradually increased with time until it reached up to 9% of the

T. Kitabatake; Y. Mizutani

1961-01-01

227

Maintaining the uranium resources data system and assessing the 1991 US uranium potential resources  

Microsoft Academic Search

The Energy Information Administration's (EIA) Uranium Resource Assessment Data (URAD) System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the URAD system; (2) to assess the 1991 U.S. uranium potential resources in various cost categories; and (3) to describe

R. B. McCammon; W. I. Finch; W. D. Grundy; C. T. Pierson

1992-01-01

228

Colorimetric detection of uranium in water  

DOEpatents

Disclosed are methods, materials and systems that can be used to determine qualitatively or quantitatively the level of uranium contamination in water samples. Beneficially, disclosed systems are relatively simple and cost-effective. For example, disclosed systems can be utilized by consumers having little or no training in chemical analysis techniques. Methods generally include a concentration step and a complexation step. Uranium concentration can be carried out according to an extraction chromatographic process and complexation can chemically bind uranium with a detectable substance such that the formed substance is visually detectable. Methods can detect uranium contamination down to levels even below the MCL as established by the EPA.

DeVol, Timothy A. (Clemson, SC); Hixon, Amy E. (Piedmont, SC); DiPrete, David P. (Evans, GA)

2012-03-13

229

Uranium Enrichment - ChemCases.com  

NSDL National Science Digital Library

Natural uranium contains 0.7205% of the U-235, the fissile isotope of uranium. There are a few U-234 atoms (0.0055%) in the remaining mass of U-238 (99.274%). Uranium-238 does not contribute to slow neutron fission; however, it does react with neutrons to form a fissile isotope of plutonium, Pu-239. Although U-235 and U-238 are chemically identical, they differ slightly in their physical properties, most importantly mass. This small mass difference allows the isotopes to be separated and makes it possible to increase ("enrich") the percentage of U-235 in uranium.

Settle, Frank

230

Chemistry of uranium in aluminophosphate glasses  

NASA Technical Reports Server (NTRS)

The U(VI)-U(V)-U(IV) redox equilibria are investigated in two sodium aluminophosphate base compositions at a variety of melt temperatures, imposed oxygen fugacities, and uranium contents. Results show that the higher redox states of uranium are quite soluble in the phosphate glasses, although U(IV) readily precipitates from the melts as UO2. In addition, comparisons of the uranium redox equilibria established in phosphate melts versus those in silicate melts shows that the coordination sites of the individual uranium species are generally the same in both solvent systems although they differ in detail.

Schreiber, H. D.; Balazs, G. B.; Williams, B. J.

1982-01-01

231

Geology of New Mexico uranium deposits  

SciTech Connect

A discussion of the geology of the uranium deposits of New Mexico was presented. Uranium has been found in all four of the physiographic provinces in New Mexico--the Colorado Plateau, the Southern Rocky Mountains, the Basin and Range, and the Great Plains. The vast majority of uranium is mined in the San Juan Basin of the Colorado Plateau in the northwest corner of New Mexico. More than 50 percent of the nation's uranium reserves are located there. The host rocks range in age from Precambrian to Quaternary and include plutonic, volcanic, and sedimentary rocks. Ten figures including maps and tables were presented in the work.

Hatchell, W.O.

1981-12-01

232

Statistical data of the uranium industry  

SciTech Connect

Statistical Data of the Uranium Industry is a compendium of information relating to US uranium reserves and potential resources and to exploration, mining, milling, and other activities of the uranium industry through 1981. The statistics are based primarily on data provided voluntarily by the uranium exploration, mining, and milling companies. The compendium has been published annually since 1968 and reflects the basic programs of the Grand Junction Area Office (GJAO) of the US Department of Energy. The production, reserves, and drilling information is reported in a manner which avoids disclosure of proprietary information.

none,

1982-01-01

233

Distribution of uranium-bearing phases in soils from Fernald  

SciTech Connect

Electron beam techniques have been used to characterize uranium-contaminated soils and the Fernald Site, Ohio. Uranium particulates have been deposited on the soil through chemical spills and from the operation of an incinerator plant on the site. The major uranium phases have been identified by electron microscopy as uraninite, autunite, and uranium phosphite [U(PO{sub 3}){sub 4}]. Some of the uranium has undergone weathering resulting in the redistribution of uranium within the soil.

Buck, E.C.; Brown, N.R.; Dietz, N.L.

1993-12-31

234

High strength and density tungsten-uranium alloys  

DOEpatents

Alloys of tungsten and uranium and a method for making the alloys. The amount of tungsten present in the alloys is from about 55 vol % to about 85 vol %. A porous preform is made by sintering consolidated tungsten powder. The preform is impregnated with molten uranium such that (1) uranium fills the pores of the preform to form uranium in a tungsten matrix or (2) uranium dissolves portions of the preform to form a continuous uranium phase containing tungsten particles.

Sheinberg, Haskell (Los Alamos, NM)

1993-01-01

235

A review of the environmental behavior of uranium derived from depleted uranium alloy penetrators  

SciTech Connect

The use of depleted uranium (DU) penetrators as armor-piercing projectiles in the field results in the release of uranium into the environment. Elevated levels of uranium in the environment are of concern because of radioactivity and chemical toxicity. In addition to the direct contamination of the soil with uranium, the penetrators will also chemically react with rainwater and surface water. Uranium may be oxidized and leached into surface water or groundwater and may subsequently be transported. In this report, we review some of the factors affecting the oxidation of the DU metal and the factors influencing the leaching and mobility of uranium through surface water and groundwater pathways, and the uptake of uranium by plants growing in contaminated soils. 29 refs., 10 figs., 3 tabs.

Erikson, R.L.; Hostetler, C.J.; Divine, J.R.; Price, K.R.

1990-01-01

236

Uranium Management - Preservation of a National Asset  

SciTech Connect

The Uranium Management Group (UMG) was established at the Department of Energy's (DOE's) Oak Ridge Operations in 1999 as a mechanism to expedite the de-inventory of surplus uranium from the Fernald Environmental Management Project site. This successful initial venture has broadened into providing uranium material de-inventory and consolidation support to the Hanford site as well as retrieving uranium materials that the Department had previously provided to universities under the loan/lease program. As of December 31, 2001, {approx} 4,300 metric tons of uranium (MTU) have been consolidated into a more cost effective interim storage location at the Portsmouth site near Piketon, OH. The UMG continues to uphold its corporate support mission by promoting the Nuclear Materials Stewardship Initiative (NMSI) and the twenty-five (25) action items of the Integrated Nuclear Materials Management Plan (1). Before additional consolidation efforts may commence to remove excess inventory from Environmental Management closure sites and universities, a Programmatic Environmental Assessment (PEA) must be completed. Two (2) noteworthy efforts currently being pursued involve the investigation of re-use opportunities for surplus uranium materials and the recovery of usable uranium from the shutdown Portsmouth cascade. In summary, the UMG is available as a DOE complex-wide technical resource to promote the responsible management of surplus uranium.

Jackson, J. D.; Stroud, J. C.

2002-02-27

237

Bioremediation of uranium contaminated soils and wastes  

SciTech Connect

Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (1) stabilization of uranium and toxic metals with reduction in waste volume and (2) removal and recovery of uranium and toxic metals from wastes and contaminated soils. Stabilization of uranium and toxic metals in wastes is accomplished by exploiting the unique metabolic capabilities of the anaerobic bacterium, Clostridium sp. The radionuclides and toxic metals are solubilized by the bacteria directly by enzymatic reductive dissolution, or indirectly due to the production of organic acid metabolites. The radionuclides and toxic metals released into solution are immobilized by enzymatic reductive precipitation, biosorption and redistribution with stable mineral phases in the waste. Non-hazardous bulk components of the waste volume. In the second process uranium and toxic metals are removed from wastes or contaminated soils by extracting with the complexing agent citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, followed by photochemical degradation of the uranium citrate complex which is recalcitrant to biodegradation. The toxic metals and uranium are recovered in separate fractions for recycling or for disposal. The use of combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in clean-up and disposal costs.

Francis, A.J.

1998-12-31

238

Characterizing In Situ Uranium and Groundwater Flux  

Microsoft Academic Search

The goal of this project is to develop a new sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of uranium and groundwater fluxes. The sensor uses two sorbents and resident tracers to measure uranium flux and specific discharge directly; but, sensor principles and design should also apply to fluxes of other

J. Cho; M. A. Newman; V. Stucker; A. Peacock; J. Ranville; S. Cabaniss; K. Hatfield; M. D. Annable; H. Klammler; I. V. Perminova

2010-01-01

239

Uranium Metal Analysis via Selective Dissolution  

Microsoft Academic Search

Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation\\/corrosion in water. A thorough knowledge of the uranium metal concentration in sludge therefore is essential to successful sludge management and waste process design. The goal of this

Calvin H. Delegard; Sergey I. Sinkov; Andrew J. Schmidt; Jeffrey W. Chenault

2008-01-01

240

Extraction of uranium from carbonaceous sandstone materials  

Microsoft Academic Search

Laboratory characterization studies have investigated the processing variability of carbonaceous uranium-bearing materials found in sandstone deposits. This work was conducted by the Federal Bureau of Mines in support of its goal to maintain an adequate supply of minerals to meet national economic and strategic needs. Conventional processing produces only partial uranium recovery from these ore materials. Ore samples from New

I. L. Nichols; A. G. Lawrence; D. C. Seidel

1979-01-01

241

Uzbekistan unveiled. [Uranium production to commence  

SciTech Connect

Through centuries of revolution, war and strife, the people of Uzbekistan have built a reputation as skilled and tenacious merchants. Since antiquity, when the Silk Road from China turned toward Europe at Smarakand, they have been master traders of such valuable commodities as cotton, fruits, vegetables, spices and gold. Now, they're about to introduce another of their specialties to the world: Uranium. Uranium mining in the country is controlled by a new, independent company, the Kizilkumredmetzoloto, parent of the Navoi Mining Metallurgy Combine [NMMC]. Established in 1958 at the height of the Cold War, when uranium mining for military stockpiles got started in earnest, Navoi was wholly owned by the USSR's Ministry of Medium Machine Building. Up until 1991, virtually all of Navoi's uranium production, strictly in the form of uranium concentrates, was used for either military purposes or for nuclear power plants within the former Soviet Union. The republic exerted no control over the final destination of its uranium. All production and operating decisions for Navoi's mines were dictated by the Soviet Union's Ministry of Atomic Power Industry [MAPI], which developed annual quotas for uranium production in each republic of the country. Uranium from the republics was sold to Techsnabexport [Tenex], the distribution and marketing arm of MAPI. Exports to other countries were handled strictly by Tenex.

Mazurkevich, A.P.

1993-05-01

242

National uranium resource evaluation. Winnemucca Quadrangle, Nevada  

Microsoft Academic Search

The Winnemucca 2° quadrangle, Nevada, was evaluated for geologic environments favorable for uranium deposits, using criteria developed for the National Uranium Resource Evaluation program. Reconnaissance radiometric and geochemical surveys were conducted for all geologic environments open to evaluation. Detailed surface and subsurface investigations were conducted in potential host and source environments. Subsurface data collected by private industry were obtained for

W. C. Berridge; N. J. Wolverson

1982-01-01

243

Tritium transport vessel using depleted uranium  

SciTech Connect

A tritium transport vessel using depleted uranium was tested in the laboratory using deuterium and protium. The vessel contains 0.5 kg of depleted uranium and can hold up to 18 grams of tritium. The conditions for activation, tritium loading and tritium unloading were defined. The safety aspects that included air-ingress, tritium diffusion, temperature and pressure potentials were evaluated.

Heung, L.K.

1995-01-01

244

SPECTROPHOTOMETRIC DETERMINATION OF SILICON IN URANIUM COMPOUNDS  

Microsoft Academic Search

On the basis of the colorimetric determination of silicon by the yellow ; silicomolybdic acid formation or by its reduction to molybdenum blue, three ; methods for the determination of the silicon in uranium are proposed. Silicon ; was determined in the solution employing the above methods after extraction of ; the uranyl nitrate by TBP. Finally a direct uranium

L. Lorenzini; C. Stoppa; W. Barbieri

1962-01-01

245

Solubility of uranium in alkaline salt solutions  

SciTech Connect

The solubility of uranium in alkaline salt solutions was investigated to screen for significant factors and interactions among the major salt components and temperature. The components included in the study were the sodium salts of hydroxide, nitrate, nitrite, aluminate, sulfate, and carbonate. General findings from the study included: (1) uranium solubilities are very low (1-20 mg/L) for all solution compositions at hydroxide concentrations from 0.1 to 17 molar (2) carbonate, sulfate, and aluminate are not effective complexants for uranium at high hydroxide concentration, (3) uranium solubility decreases with increasing temperature for most alkaline salt solutions, and (4) uranium solubility increases with changes in solution chemistry that reflect aging of high level waste (increase in nitrite and carbonate concentrations, decrease in nitrate and hydroxide concentrations). A predictive model for the concentration of uranium as a function of component concentrations and temperature was fitted to the data. All of the solution components and temperature were found to be significant. There is a significant lack of fit for the model, which suggests that the dependence on the uranium solubility over the wide range of solution compositions is non-linear and/or that there are other uncontrolled parameters which are important to the uranium solubility.

Hobbs, D.T.; Edwards, T.B.

1994-03-29

246

Extracting Uranium from a Wyoming Granite.  

National Technical Information Service (NTIS)

The Bureau of Mines is examining a variety of low-grade uranium ores because projections indicate that an appreciable percentage of future U.S. uranium production will be derived from resources containing 0.01 to 0.1 percent U3O8. One possible source is r...

J. H. Maysilles I. L. Nichols D. C. Seidel

1977-01-01

247

National Uranium Resource Evaluation: Escalante Quadrangle, Utah.  

National Technical Information Service (NTIS)

Seven areas favorable for the occurrence of uranium deposits meet the minimum size and grade requirements of the National Uranium Resource Evaluation of the US Department of Energy in the Escalante 1 exp 0 x 2 exp 0 Quadrangle, South-Central Utah. Five ar...

F. Peterson, J. A. Campbell, K. J. Franczyk, R. D. Lupe

1982-01-01

248

Development of a Colorimetric Test for Uranium.  

National Technical Information Service (NTIS)

This paper discusses the development of and proposed enhancements to a colorimetric test for the detection of uranium in biological samples such as urine. The goal of this work is to develop a technique for the detection of uranium that could: (1) be cond...

D. E. McClain J. F. Kalinich

2005-01-01

249

Uranium Distribution along the Salinity Gradient  

NASA Astrophysics Data System (ADS)

Uranium distribution has been examined in the estuarine waters of the Keum River, Korea. Water samples were collected along a salinity gradient, range from 0.2 to 31.5 psu. Dissolved uranium in the samples has been extracted by C-18 SPE cartridge after pre-treatment. Extraction of uranium by C-18 cartridge after complexation with APDC/DDDC shows about 90 % recovery. After concentration of sample onto C-18 cartridge, uranium complex has been sequentially extracted by 50 % and 100 % acetonitrile, respectively. Result shows good recovery efficiency at low pH (2.5 _ 3.0) during the pre-treatment of sample which was presumably related with destabilization of uranium-carbonate complex. In the estuary, uranium shows typical conservative behavior along the salinity gradient. The current result substantiates earlier reports that uranium is conservatively transported from the river to the ocean. Most of dissolved trace metals, except cadmium, decreased with increasing salinity in the estuary. Dissolved organic carbon also decreased along the salinity gradient. Copper was rapidly removed during the mixing with seawaters as a result of organic matter flocculation. Dissolved molybdenum, vanadium and uranium distribution in the estuary showed similarities that those concentration increase along the salinity gradient.

Yoon, C.; Yoon, H.; Seo, J.; Lee, J.; Chung, K.

2006-12-01

250

Progress toward uranium scrap recycling via EBCHR.  

National Technical Information Service (NTIS)

A 250 kW electron beam cold hearth refining (EBCHR) melt furnace at Lawrence Livermore National Laboratory (LLNL) has been in operation for over a year producing 5.5 in.-diameter ingots of various uranium alloys. Production of in-specification uranium-6%-...

R. H. McKoon

1994-01-01

251

Estimating U.S. uranium reserves  

NASA Astrophysics Data System (ADS)

This article presents information on the Energy Information Administrations (U.S. Department of Energy) annual estimates of U.S. uranium reserves. Encompassed is information for year-end 1997s uranium reserves, which were estimated by employing numerous resources.

Smith, L. L.

1998-12-01

252

Microbial uptake of uranium, cesium, and radium  

SciTech Connect

The ability of diverse microbial species to concentrate uranium, cesium, and radium was examined. Saccharomyces cerevisiae, Pseudomonas aeruginosa, and a mixed culture of denitrifying bacteria accumulated uranium to 10 to 15% of the dry cell weight. Only a fraction of the cells in a given population had visible uranium deposits in electron micrographs. While metabolism was not required for uranium uptake, mechanistic differences in the metal uptake process were indicated. Uranium accumulated slowly (hours) on the surface of S. cerevisiae and was subject to environmental factors (i.e., temperature, pH, interfering cations and anions). In contrast, P. aeruginosa and the mixed culture of denitrifying bacteria accumulated uranium rapidly (minutes) as dense, apparently random, intracellular deposits. This very rapid accumulation has prevented us from determining whether the uptake rate during the transient between the initial and equilibrium distribution of uranium is affected by environmental conditions. However, the final equilibrium distributions are not affected by those conditions which affect uptake by S. cerevisiae. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several microbial species tested. The potential utility of microorganisms for the removal and concentration of these metals from nuclear processing wastes and several bioreactor designs for contacting microorganisms with contaminated waste streams will be discussed.

Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; McWhirter, D.A.

1980-01-01

253

Bernabe Montano uranium deposit, Sandoval County  

Microsoft Academic Search

Uranium mineralization was discovered on the Bernabe Montano Grant early in 1971. This old land grant, which is part of the Laguna Indian Reservation, is approximately 25 mile northwest of Albuquerque, New Mexico. About 2,000 holes have been drilled on this property to date, and an ore reserve of 10 to 20 million lbs of uranium oxide has been delineated

R. G. Kozusko; A. E. Saucier

1980-01-01

254

Exploration for uranium deposits, Grants mineral belt  

Microsoft Academic Search

Uranium ore deposits in the Grants mineral belt, New Mexico, occur in fluvial sandstones in the Morrison Formation (Jurassic). Uranium mineralization is concentrated by a dark-gray to black substance that has been identified as humate, which is derived from decaying vegetation. Black ore is truncated by overlying sandstone in at least three ore deposits, documenting an early age for mineralization.

Fitch

1980-01-01

255

SANS Measurement of Hydrides in Uranium  

Microsoft Academic Search

SANS scattering is shown to be an effective method for detecting the presence of hydrogen precipitates in uranium. High purity polycrystalline samples of depleted uranium were given several hydriding treatments which included extended exposures to hydrogen gas at two different pressures at 630 C as well as a furnace anneal at 850 C followed by slow cooling in the near

S. Spooner; G. M. Ludtka; J. S. Bullock; R. L. Bridges; G. L. Powell

2001-01-01

256

Uranium settling rates in SRS waste supernate.  

National Technical Information Service (NTIS)

The evaporation of SRS High Level Waste supernate is accompanied by a decrease in the solubility of uranium, and thus uranium precipitates as the complex compound usually referred to as Na(sub 2)U(sub 2)O(sub 7). The precipitated Na(sub 2)U(sub 2)O(sub 7)...

D. G. Karraker

1994-01-01

257

Mechanochemical synthesis of uranium sesquisilicide  

NASA Astrophysics Data System (ADS)

Uranium sesquisilicide (U3Si2) has been prepared by high energy ball milling of the elemental powders. Starting materials were combined in a planetary ball mill and milled with a 10:1 ball-to-powder charge for varying times between 0 and 24 h. Temperature and pressure of the milling vial were monitored to gain insight into reaction kinetics. The development of USi3 as an intermediate phase is discussed. Starting materials and as-milled powders were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), demonstrating the viability of mechanochemical synthesis for U3Si2.

Alanko, Gordon A.; Butt, Darryl P.

2014-08-01

258

Monoiodoacetates of uranium (IV) and thorium  

SciTech Connect

Monoiodoacetates of thorium, viz., the normal compound Th(CH/sub 2/ICOO)/sub 2/ and the basic compound ThO(CH/sub 2/ICOO)/sub 2/.H/sub 2/O, and uranium(IV) oxyiodoacetate UO(CH/sub 2/CIOO)/sub 2/'H/sub 2/O have been synthesized and investigated with the use of a set of physicochemical methods (thermogravimetry, x-ray diffraction analysis, IR spectroscopy). The process of the thermal decomposition of these compounds has been studied under poly- and isothermal conditions. The thermolysis involves the formation of the carbonate, and the final decomposition product is a dioxide containing a large quantity of free carbon. A possible scheme for the occurence of thermolysis has been proposed.

Matveev, Y.S.; Dunaeva, K.M.

1986-03-01

259

Method for fabricating laminated uranium composites  

DOEpatents

The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

Chapman, L.R.

1983-08-03

260

New treatment for uranium in wastewater  

SciTech Connect

The design of an advanced wastewater treatment facility at the Fernald Environmental Management Project (FEMP) near Cincinnati, Ohio, focuses on minimizing discharge of uranium and other priority pollutant metals. The treatment facility will use chemical pretreatment to remove most dissolved and suspended solids, radionuclides, and priority pollutant metals. Ion exchange will be used to ensure that the concentration of uranium discharged to the environment is less than 1.0 [mu]g/L. Designers have evaluated a potassium ferrate (iron VI) treatment procedure for uranium removal, focusing not only on the treatment's efficiency in removing uranium, but also on the volume of contaminated solids that are generated. When performance levels for removal of uranium, volume of contaminated solids generated, and overall costs of treatment and waste removal are considered, potassium ferrate technology compares favorably with conventional treatments. 2 tabs.

Potts, M.E. (Analytical Development Corp., Colorado Springs, CO (United States)); Hampshire, L.H. (Westinghouse Environmental Management Co. of Ohio, Cincinnati (United States))

1993-01-01

261

Thermal Analysis of Uranium Dioxide.  

National Technical Information Service (NTIS)

The oxidation of UO sub 2 was studied by thermogravimetric and differential thermal analysis. It was verified that the physical history of the sample, together with the experimental conditions significantly influenced the oxidation steps, respectively the...

C. N. Turcanu P. Georgeoni R. Deju

1978-01-01

262

Removal of uranium from uranium-contaminated soils -- Phase 1: Bench-scale testing. Uranium in Soils Integrated Demonstration  

SciTech Connect

To address the management of uranium-contaminated soils at Fernald and other DOE sites, the DOE Office of Technology Development formed the Uranium in Soils Integrated Demonstration (USID) program. The USID has five major tasks. These include the development and demonstration of technologies that are able to (1) characterize the uranium in soil, (2) decontaminate or remove uranium from the soil, (3) treat the soil and dispose of any waste, (4) establish performance assessments, and (5) meet necessary state and federal regulations. This report deals with soil decontamination or removal of uranium from contaminated soils. The report was compiled by the USID task group that addresses soil decontamination; includes data from projects under the management of four DOE facilities [Argonne National Laboratory (ANL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and the Savannah River Plant (SRP)]; and consists of four separate reports written by staff at these facilities. The fundamental goal of the soil decontamination task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics or generating waste forms that are difficult to manage and/or dispose of. Emphasis in research was placed more strongly on chemical extraction techniques than physical extraction techniques.

Francis, C. W.

1993-09-01

263

Uranium Pyrophoricity Phenomena and Prediction  

SciTech Connect

We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

DUNCAN, D.R.

2000-04-20

264

Storage vault for uranium oxide  

SciTech Connect

This paper describes the conceptual design of a vault for storing uranium oxide. Unique features of this vault are the storage racks and the method of surveillance. Uranium oxide packaged in 2-l canisters would be stored in a borated concrete slab placed on the vault floor. The slab would be constructed with a rectangular array of vertical holes, each of which could contain up to two canisters. Each hole would be covered with a square tile to serve as a radiation shield and to prevent casual entry. Canisters would be held one atop the other in a basket attached to the lower surface of each tile. Continual surveillance of each storage position would be provided by a network of light sources and photosensors located along opposite edges of the storage rack such that two light beams intersect perpendicularly above each storage hole but below the radiation shield. Accessing a hole activates a unique pair of photosensors, identifying the position to the value inventory control computer system. Protection against adversarial attack and intrusion detection during nonworking hours would be provided by standard methods used in the industry. The photosensor system would protect against insiders working in collusion to divert material. This would be accomplished by limiting the material vulnerable to diversion to that authorized for access.

Hooker, G.J.

1987-01-01

265

Laser melting of uranium carbides  

NASA Astrophysics Data System (ADS)

In the context of the material research aimed at supporting the development of nuclear plants of the fourth Generation, renewed interest has recently arisen in carbide fuels. A profound understanding of the behaviour of nuclear materials in extreme conditions is of prime importance for the analysis of the operation limits of nuclear fuels, and prediction of possible nuclear reactor accidents. In this context, the main goal of the present paper is to demonstrate the feasibility of laser induced melting experiments on stoichiometric uranium carbides; UC, UC 1.5 and UC 2. Measurements were performed, at temperatures around 3000 K, under a few bars of inert gas in order to minimise vaporisation and oxidation effects, which may occur at these temperatures. Moreover, a recently developed investigation method has been employed, based on in situ analysis of the sample surface reflectivity evolution during melting. Current results, 2781 K for the melting point of UC, 2665 K for the solidus and 2681 K for the liquidus of U 2C 3, 2754 K for the solidus and 2770 K for the liquidus of UC 2, are in fair agreement with early publications where the melting behaviour of uranium carbides was investigated by traditional furnace melting methods. Further information has been obtained in the current research about the non-congruent (solidus-liquidus) melting of certain carbides, which suggest that a solidus-liquidus scheme is followed by higher ratio carbides, possibly even for UC 2.

Utton, C. A.; De Bruycker, F.; Boboridis, K.; Jardin, R.; Noel, H.; Guneau, C.; Manara, D.

2009-03-01

266

Identification of uranium enrichment scenarios by multi-method characterisation of immobile uranium phases  

NASA Astrophysics Data System (ADS)

We investigate natural uranium occurrences as analogues for uranium migration and immobilisation in the post-operational phase of a radioactive waste repository. These investigations are aimed at gaining insight into the behaviour of uranium in a complex natural system. We characterise the immobile uranium phase and trace elements distributions in argillaceous uranium-rich samples from the Ruprechtov site, Czech Republic, applying a combination of different analytical methods. We use wet chemistry to determine the distribution of U(IV) and U(VI), sequential extraction to characterise different uranium phases, and 234 U/ 238U-activity ratios to correlate results between U(IV) and U(VI) distributions and the various uranium phases. Most of the uranium was determined to occur in a very long-term stable, tetravalent phase. Results from chemical methods are in good agreement with the results from spectroscopic methods. U(IV) mineral phases are identified by SEM-EDX spectroscopy and synchrotron-based ?-EXAFS. Electron-microprobe analysis confirmed that uraninite is newly formed and not a relictic phase from the altered granite. Correlation of uranium with As(V) located on thin As-rich layers on pyrite surfaces determined by confocal ?-XRF supports element correlations obtained by the sequential extraction. The key processes involved in uranium immobilisation in the argillaceous layers have been identified and can be used to reconstruct the geological history at the site.

Noseck, Ulrich; Brasser, Thomas; Suksi, Juhani; Havlov, Vclava; Hercik, Mirek; Denecke, Melissa A.; Frster, Hans-Jrgen

267

Favorability for uranium in tertiary sedimentary rocks, southwestern Montana  

Microsoft Academic Search

Tertiary sedimentary rocks in the basins of southwestern Montana were studied to determine their favorability for potential uranium resources. Uranium in the Tertiary sedimentary rocks was probably derived from the Boulder batholith and from silicic volcanic material. The batholith contains numerous uranium occurrences and is the most favorable plutonic source for uranium in the study area. Subjective favorability categories of

M. A. Wopat; W. E. Curry; J. W. Robins; D. K. Marjaniemi

1977-01-01

268

Surficial origin of North American pitchblende and related uranium deposits  

Microsoft Academic Search

The ubiquitous association of pitchblende uranium deposits with terrestrial sediments is believed to be the natural result of formation of the orebodies by surficial processes operating under continental conditions. The major uranium deposits of North America illustrate this. The quartz-pebble conglomerate uranium deposits of Elliot Lake, Ontario, have thorium-rich uranium minerals that indicate a detrital origin. With the development of

Langford

1977-01-01

269

Exploring Uranium Resource Constraints on Fissile Material Production in Pakistan  

Microsoft Academic Search

This paper evaluates possible scenarios for Pakistan's uranium enrichment and plutonium production programs since the late 1970s by using Pakistan's supply of natural uranium as a constraint. Since international sanctions have prevented Pakistan from importing uranium for decades, it has had to rely on domestic uranium productioncurrently estimated as approximately 40 tons a year. The paper divides the development of

ZIA MIAN; A. H. NAYYAR; R. RAJARAMAN

2009-01-01

270

Organic matter and sandstone-type uranium deposits: a primer  

USGS Publications Warehouse

Organic material is intimately associated with sandstone-type uranium deposits in the western United States.. This report gives details of the types of organic matter and their possible role in producing a uranium deposit. These steps include mobilization of uranium from igneous rocks, transportation from the surface, concentration by organic matter, reduction by organic matter, and preservation of the uranium deposit.

Leventhal, Joel S.

1979-01-01

271

Qualitative Analysis by Photoacoustic Spectroscopy of Amorphous Uranium Tetrafluoride Deposits  

Microsoft Academic Search

Recent studies concerning uranium plasma chemistry have confirmed the generally complicated nature of uranium chemistry. Uranium plasma, generated by either rf-heating or dc arc torch argon heating of uranium hexafluoride, tends to react with its environment to produce among other compounds both fluorides and oxy-fluorides. The products are characterized as amorphous, powdery deposits. While uranyl fluoride can be identified readily

H. E. Eaton; D. R. Anton; J. D. Stuart

1977-01-01

272

ACID LEACHING OF URANIUM FROM SOME SOUTH DAKOTA LIGNITES  

Microsoft Academic Search

The effect of different variables, such as acid concentration, leaching ; time, oxidation, rate and mode of agitation, temperature, and pulp density on the ; recovery of uranium from three samples of uranium-bearing lignites from South ; Dakota with high, intermediate, and low uranium contents was studied. The ; recovery of uranium increases with increase in acid concentration, leaching time,

S. Sun; J. W. Fetterman

1963-01-01

273

SOME DATE ON THE ANALYSIS OF URANIUM, THORIUM, AND ZIRCONIUM  

Microsoft Academic Search

Considering the physicochemical conditions for tributyl phosphate (TBP) ; uranium extraction, an optimum nitrate concentration of the aqueous phase is ; found, in which uranium separation by single extraction amounts virtually to 100%. ; The extraction is carried out in TBP-petrol solution and the uranium is re-; extracted in a dilute ammonium carbonate solution. The uranium content can be ;

G. Almassy; M. Oerdoegh; A. Schneer

1958-01-01

274

Carbon reduction in uranium alloys utilizing hafnium additions  

Microsoft Academic Search

With increasing environmental concerns regarding the handling and storage of uranium waste, recycling previously used material is becoming exceedingly more important. Carbon is one of the primary trace impurities that builds up in uranium with repeated use. The goal of this study is to reduce carbon in recycled uranium during the casting process to carbon levels associated with virgin uranium

G. Mackiewicz-Ludtka; W. C. Pullen; C. A. Henderson; W. Chu; M. W. Wendel

1990-01-01

275

Batch Tests with unirradiated uranium metal fuel program report.  

SciTech Connect

Although the general environment of the proposed repository at Yucca Mountain is expected to be oxidizing in nature, the local chemistry within fuel canisters may be otherwise. The combination of low dissolved oxygen and corrosion of metallic fuels, such as Hanford's N-Reactor inventory, may produce reducing conditions. This condition may persist for periods sufficient to affect the corrosion and paragenesis of fuels and their reaction products. Starting in September 2001, unirradiated metallic uranium fuel was examined during batch tests under anoxic conditions. A series of tests carried out under inert atmosphere highlighted the rapid corrosion of the metallic uranium in EJ-13 water at 90 C. During the oxidation of the uranium, uranium dioxide fines spilled from the fuel surface generating copious amounts of colloids. The proportion of uranium-associated colloids accounted for nearly 50% to >99% of the uranium in solution after a brief period where no colloids were detected. The colloids were identified as individual (<10nm) and agglomerated uranium dioxide spheres as large as a few hundred nanometers in size. Silicate and alumino-silicate clays of diverse size and shape were also identified. The bulk size distribution as measured by dynamic light scattering was consistent with the microscopy observations in that the polydispersity indices were large, indicating a wide distribution of colloid particle sizes. The colloids were found to persist for periods beyond the scope of these tests and are at least partly stable. The anoxic experiments suggest that at least two mechanisms are responsible for uranium corrosion. The initial corrosion period is variably long but may last more than one month during which there is no net release of gas. Calculations of oxygen concentration in the vessel at the time of vessel closure show that this period is not consistent with the presence of dissolved oxygen, which would suppress H{sub 2} production in undersaturated conditions. After this induction period, the fuel begins to produce H{sub 2} gas until the coupon completely disaggregates into fine UO{sub 2+x} powder.

Kaminski, M. D.

2002-02-21

276

Fuel powder production from ductile uranium alloys.  

SciTech Connect

Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. Grinding was found to be inefficient and introduced impurities into the fuel. Cryogenic milling of machine chips in a steel vial was found to have similar shortcomings. The hydride-dehydride process has historically been used to produce very fine powder that may not be suitable for fuel fabrication. Uranium is made to form its hydride by heating in a hydrogen atmosphere. Subsequent heating under vacuum drives off hydrogen gas and returns the hydride to a metallic state. The volume change on hydride formation results in a fine powder upon dehydriding. The effects of alloying elements, partial hydriding, and subsequent milling treatments on particle size distribution are being explored. Inert gas atomization is used on an industrial scale to produce metal powder. Current designs are not suitable for use with uranium. A system was specifically designed for uranium atomization. A prototype was built and tested using gold as a surrogate for uranium. The system operates efficiently and can produce powder in a variety of size ranges by changing the atomization nozzle.

Clark, C. R.

1998-10-23

277

Bacterial leaching of waste uranium materials.  

PubMed

The effect of ferrobacteria and thiobacteria on the leaching of waste uranium materials from which 70-80% of uranium was previously leached by classical chemical hydrometallurgical procedure has been investigated. The bacteria used are found in the ore and the mine water of Zletovska River locality, Yugoslavia. Parameters of biological leaching were examined in the laboratory. Leaching conditions were changed with the aim of increasing the amount of uranium leached. The effect of pyrite added to the waste materials before the beginning of leaching has also been examined. Uranium leaching is directly proportional to the composition and number of ferrobacteria and thiobacteria, and increased by almost twice the value obtained from the same starting materials without using bacteria. Increased sulphuric acid concentrations stimulate considerably the rate of leaching. Uranium leaching is increased up to 20% while sulphuric acid consumption is simultaneously decreased by the addition of pyrite. Uranium concentrations in starting waste materials used for leaching were extremely low (0.0278 and 0.372% U) but about 60% recovery of uranium was obtained, with relatively low consumption of sulphuric acid. PMID:788361

Barbic, F F; Bracilovi?, D M; Krajincani?, B V; Luci?, J L

1976-01-01

278

Uranium content and leachable fraction of fluorspars.  

PubMed

Much attention in the radiological health community has recently focused on the management and regulation of naturally occurring radioactive materials. Although uranium-bearing minerals are present in a variety of fluorspar deposits, their potential consideration as naturally occurring radioactive materials has received only limited recognition. The uranium content of 28 samples of acid- and cryolite-grade (>97% CaF2) fluorspar from the National Defense Stockpile was found to range from 120 to 24,200 microg kg(-1), with a mean of 2,145 microg kg(-1). As a point of comparison, the average concentration of uranium in the upper crust of the earth is about 2,500 microg kg(-1). Leachability of this uranium was assessed by means of the Toxicity Characteristic Leaching Procedure (TCLP). The TCLP extractable fraction ranged from 1 to 98%, with a mean of 24% of the total uranium. The typically low concentrations of uranium seen in these materials probably reflects the removal of uranium-bearing mineral phases during the beneficiation of the crude fluorspar ore to achieve industrial specifications. Future NORM studies should examine crude fluorspar ores and flotation tailings. PMID:10949254

Landa, E R; Councell, T B

2000-09-01

279

Maintaining the Uranium Resources Assessment Data System and assessing the 1990 US uranium potential resources. Final report  

Microsoft Academic Search

The Energy Information Administration`s (EIA) Uranium Resource Assessment Data System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the Uranium Resource Assessment Data (URAD) System, (2) to assess the 1990 US uranium potential resources in various cost categories, and

R. B. McCammon; W. I. Finch; W. D. Grundy; C. T. Pierson

1991-01-01

280

Electrolytic process for preparing uranium metal  

DOEpatents

An electrolytic process for making uranium from uranium oxide using Cl.sub.2 anode product from an electrolytic cell to react with UO.sub.2 to form uranium chlorides. The chlorides are used in low concentrations in a melt comprising fluorides and chlorides of potassium, sodium and barium in the electrolytic cell. The electrolysis produces Cl.sub.2 at the anode that reacts with UO.sub.2 in the feed reactor to form soluble UCl.sub.4, available for a continuous process in the electrolytic cell, rather than having insoluble UO.sub.2 fouling the cell.

Haas, Paul A. (Knoxville, TN)

1990-01-01

281

Statistical data of the uranium industry  

SciTech Connect

This report is a compendium of information relating to US uranium reserves and potential resources and to exploration, mining, milling, and other activities of the uranium industry through 1982. The statistics are based primarily on data provided voluntarily by the uranium exploration, mining and milling companies. The compendium has been published annually since 1968 and reflects the basic programs of the Grand Junction Area Office of the US Department of Energy. Statistical data obtained from surveys conducted by the Energy Information Administration are included in Section IX. The production, reserves, and drilling data are reported in a manner which avoids disclosure of proprietary information.

none,

1983-01-01

282

Uranium nitride behavior at thermionic temperatures  

NASA Technical Reports Server (NTRS)

The feasibility of using uranium nitride for in-core thermionic applications was evaluated in electrically heated thermal gradient tests and in flat plate thermionic converters. These tests indicated that grain boundary penetration of uranium nitride into both tungsten and rhenium will occur under thermal gradient conditions. In the case of the tungsten thermionic converter, this led to grain boundary rupture of the emitter and almost total loss of electrical output from the converter. It appears that uranium nitride is unsuitable for thermionic applications at the 2000 K temperatures used in these tests.

Phillips, W. M.

1973-01-01

283

Uranium in saline lakes of Northwestern Mongolia  

NASA Astrophysics Data System (ADS)

Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).

Isupov, V. P.; Vladimirov, A. G.; Lyakhov, N. Z.; Shvartsev, S. L.; Ariunbileg, S.; Kolpakova, M. N.; Shatskaya, S. S.; Chupakhina, L. E.; Kuibida, L. V.; Moroz, E. N.

2011-03-01

284

Capstone Depleted Uranium Aerosols: Generation and Characterization  

SciTech Connect

In a study designed to provide an improved scientific basis for assessing possible health effects from inhaling depleted uranium (DU) aerosols, a series of DU penetrators was fired at an Abrams tank and a Bradley fighting vehicle. A robust sampling system was designed to collect aerosols in this difficult environment and continuously monitor the sampler flow rates. Aerosols collected were analyzed for uranium concentration and particle size distribution as a function of time. They were also analyzed for uranium oxide phases, particle morphology, and dissolution in vitro. The resulting data provide input useful in human health risk assessments.

Parkhurst, MaryAnn; Szrom, Fran; Guilmette, Ray; Holmes, Tom; Cheng, Yung-Sung; Kenoyer, Judson L.; Collins, John W.; Sanderson, T. Ellory; Fliszar, Richard W.; Gold, Kenneth; Beckman, John C.; Long, Julie

2004-10-19

285

Uranium\\/plutonium and uranium\\/neptunium separation by the Purex process using hydroxyurea  

Microsoft Academic Search

Hydroxyurea dissolved in nitric acid can strip plutonium and neptunium from tri-butyl phosphate efficiently and has little\\u000a influence on the uranium distribution between the two phases. Simulating the 1B contactor of the Purex process by hydroxyurea\\u000a with nitric acid solution as a stripping agent, the separation factors of uranium\\/plutonium and uranium\\/neptunium can reach\\u000a values as high as 4.7. 104 and

Zhu Zhaowu; He Jianyu; Zhang Zefu; Zhang Yu; Zhu Jianmin; Zhen Weifang

2004-01-01

286

Uranium\\/plutonium and uranium\\/neptunium separation by the Purex process using hydroxyurea  

Microsoft Academic Search

Hydroxyurea dissolved in nitric acid can strip plutonium and neptunium from tri-butyl phosphate efficiently and has little influence on the uranium distribution between the two phases. Simulating the 1B contactor of the Purex process by hydroxyurea with nitric acid solution as a stripping agent, the separation factors of uranium\\/plutonium and uranium\\/neptunium can reach values as high as 4.7104 and 260,

Zhu Zhaowu; He Jianyu; Zhang Zefu; Zhang Yu; Zhu Jianmin; Zhen Weifang

2004-01-01

287

Maintaining the uranium resources data system and assessing the 1991 US uranium potential resources. Final report  

Microsoft Academic Search

The Energy Information Administration`s (EIA) Uranium Resource Assessment Data (URAD) System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the URAD system; (2)to assess the 1991 U.S. uranium potential resources in various cost categories; and (3) to describe the

R. B. McCammon; W. I. Finch; W. D. Grundy; C. T. Pierson

1992-01-01

288

Maintaining the uranium resources data system and assessing the 1991 US uranium potential resources  

SciTech Connect

The Energy Information Administration's (EIA) Uranium Resource Assessment Data (URAD) System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the URAD system; (2) to assess the 1991 U.S. uranium potential resources in various cost categories; and (3) to describe the progress that has been made to automate the generation of the assessment reports and their subsequent transmittal by diskette.

McCammon, R.B. (Geological Survey, Reston, VA (United States)); Finch, W.I.; Grundy, W.D.; Pierson, C.T. (Geological Survey, Denver, CO (United States))

1992-12-31

289

Corrosion resistance of zinc coatings on depleted uranium and uranium alloys  

SciTech Connect

Simulated atmospheric corrosion studies were performed to determine the corrosion protection provided by galvanized zinc coatings on depleted uranium, U-0.75 Ti alloy, and U-6 Nb alloys. The accelerated ASTM tests consisted of exposing the galvanized samples to aqueous and aqueous chloride environments. The test results showed that anodic protection was provided by the electronegative zinc coatings on uranium and uranium alloys. Treating zinc with chromate conversion coatings also provided more protection.

Briggs, J.L.

1985-01-27

290

Energy spectrum of sputtered uranium  

NASA Technical Reports Server (NTRS)

The fission track technique for detecting uranium 235 was used in conjunction with a mechanical time-of-flight spectrometer to measure the energy spectrum in the region 1 eV to 1 keV of material sputtered from a 93% enriched U-235 foil by 80 keV Ar-40(+) ions. The spectrum was found to exhibit a peak in the region 2-4 eV and to decrease approximately as E to the -1.77 power for E is approximately greater than 100 eV. The design, construction and resolution of the mechanical spectrometer are discussed and comparisons are made between the data and the predictions of the ramdom collision cascade model of sputtering.

Weller, R. A.; Tombrello, T. A.

1977-01-01

291

Uranium isotopic composition and uranium concentration in special reference material SRM A (uranium in KCl/LiCl salt matrix)  

SciTech Connect

To help assure that analysis data of known quality will be produced in support of demonstration programs at the Fuel Conditioning Facility at Argonne National Laboratory-West (Idaho Falls, ID), a special reference material has been prepared and characterized. Designated SRM A, the material consists of individual units of LiCl/KCl eutectic salt containing a nominal concentration of 2.5 wt. % enriched uranium. Analyses were performed at Argonne National Laboratory-East (Argonne, IL) to determine the uniformity of the material and to establish reference values for the uranium concentration and uranium isotopic composition. Ten units from a batch of approximately 190 units were analyzed by the mass spectrometric isotope dilution technique to determine their uranium concentration. These measurements provided a mean value of 2.5058 {+-} 0.0052 wt. % U, where the uncertainty includes estimated limits to both random and systematic errors that might have affected the measurements. Evidence was found of a small, apparently random, non-uniformity in uranium content of the individual SRM A units, which exhibits a standard deviation of 0.078% of the mean uranium concentration. Isotopic analysis of the uranium from three units, by means of thermal ionization mass spectrometry with a special, internal-standard procedure, indicated that the uranium isotopy is uniform among the pellets with a composition corresponding to 0.1115 {+-} 0.0006 wt. % {sup 234}U, 19.8336 {+-} 0.0059 wt. % {sup 235}U, 0.1337 {+-} 0.0006 wt. % {sup 236}U, and 79.9171 {+-} 0.0057 wt. % {sup 238}U.

Graczyk, D.G.; Essling, A.M.; Sabau, C.S.; Smith, F.P.; Bowers, D.L.; Ackerman, J.P.

1997-07-01

292

Isotopic evidence of natural uranium and spent fuel uranium releases into the environment.  

PubMed

Uranium and plutonium isotopes were measured in soils, sediments and waters in an area subject to the past and present discharges from the uranium conversion plant of Malvsi (France). The isotopes (236)U and (239)Pu are well known activation products of uranium and they prove to be powerful tracers of spent fuel releases in soils and sediments. On the other hand (234)U and (238)U activities measured in waters can be used to distinguish between releases and background uranium sources. Such findings contribute to improve the monitoring of the actinides releases by nuclear fuel facilities (mining sites, conversion, enrichment and fuel plants, reprocessing plants). PMID:21132170

Pourcelot, L; Boulet, B; Le Corre, C; Loyen, J; Fayolle, C; Tournieux, D; Van Hecke, W; Martinez, B; Petit, J

2011-02-01

293

Monobromoacetates of uranium(IV) and thorium  

SciTech Connect

The monobromoacetates of thorium Th(CH/sub 2/BrCOO)/sub 4/, ThOH(CH/sub 2/BrCOO)/sub 3/ x H/sub 2/O, and ThO(CH/sub 2/BrCOO)/sub 2/ x H/sub 2/O and the monobromoacetates of uranium(IV) UCl/sub 2/ (CH/sub 2/BrCOO)/sub 2/ and UO(CH/sub 2/BrCOO)/sub 2/ x H/sub 2/O have been obtained and investigated with the use of a number of physicochemical methods (thermogravimetry, combined TG-DTG-DTA, x-ray diffraction analysis, and IR spectroscopy). The process of the thermal decomposition of these compounds under poly- and isothermal conditions has been studied. The thermolysis takes place in the 260-490/sup 0/C temperature range and involves the formation of oxo compounds. The final decomposition product is a metal dioxide containing significant (from 1 to 3 C atoms/An atom) quantities of free carbon. The volatile decomposition products are monobromoacetic acid, its anhydride, its acid bromide, formaldehyde, carbon monoxide, carbon dioxide, and hydrogen bromide. A possible scheme for the occurrence of the thermolysis has been proposed.

Matveev, Yu.S.; Dunaeva, K.M.

1986-04-01

294

TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER  

SciTech Connect

The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction mechanism is warranted to resolve the remaining discrepancies between the predicted mechanisms and experimental observations.

Westbrook, M.; Becnel, J.; Garrison, S.

2010-02-25

295

Swelling of Uranium Alloys at High Exposures  

SciTech Connect

This reports summarizes the results of postirradiation examinations of a series of unrestrained dilute uranium alloy specimens irradiated to exposures up to 13,000 MWD/T in NaK-containing stainless steel capsules.

McDonell, W.R.

2001-03-26

296

Indian Creek uranium prospects, Beaver County, Utah  

USGS Publications Warehouse

The secondary uranium minerals metatorbernite (?) and autunite (?) were discovered at Indian Creek in the spring of 1950. The deposits, in sec. 26, T. 27 S., R. 6 T., Beaver County, Utah, are 20 miles west of Marysvale, and about three-eighths of a mile east of a quartz monzonite stock. The uranium minerals are sparsely disseminated in argillized and silicified earlier Tertiary Bullion Canyon latite and related volcanic rock beneart, but close to, the contact of the overlying later Tertiary Mount Belknap gray rhyolite. The prospects are in a landslide area where exposures are scarce. Therefore, trend and possible continuity of the altered and the uraniferous zones cannot be established definitely. The occurrence of secondary uranium minerals in beidellite-montmorillonite rock, formed by alteration of earlier Tertiary rocks near a quartz monzonite stock, is similar to that in some of the deposits in the Marysvale uranium district.

Wyant, Donald G.; Stugard, Frederick, Jr.

1951-01-01

297

Uranium Metal Analysis via Selective Dissolution.  

National Technical Information Service (NTIS)

Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation/corrosion in water. A thorou...

A. J. Schmidt C. H. Delegard J. W. Chenault S. D. Sinkov

2008-01-01

298

Spectrophotometric Determination of Uranium Using Quercetin.  

National Technical Information Service (NTIS)

A spectrophotometric method for quantitative determination of uranium, using a flavone (quercetin) as complexing agent, is described. The method is based on the reaction between uranyl ion and alcoholic solution of quercetin with a complex formation of in...

A. R. Barros

1972-01-01

299

Neurotoxicity From Chronic Exposure to Depleted Uranium.  

National Technical Information Service (NTIS)

This project is designed to test the hypothesis that chronic exposure to depleted uranium (DU) impairs neuronal processes underlying cognitive function via alterations induced at hippocampal glutamatergic synapses. As prescribed by the Statement of Work, ...

S. M. Lasley

2004-01-01

300

Decarburization of Uranium Via Electron Beam Processing.  

National Technical Information Service (NTIS)

For many commercial and military applications, the successive Vacuum Induction Melting of uranium metal in graphite crucibles results in a product which is out of specification in carbon. The current recovery method involves dissolution of the metal in ac...

R. H. McKoon

1998-01-01

301

Uranium casting furnace automatic temperature control development.  

National Technical Information Service (NTIS)

Development of an automatic molten uranium temperature control system for use on batch-type induction casting furnaces is described. Implementation of a two-color optical pyrometer, development of an optical scanner for the pyrometer, determination of fur...

R. F. Lind

1992-01-01

302

Uranium Dissolution from Calciothermic and Magnesiothermic.  

National Technical Information Service (NTIS)

A laboratory study to recover uranium from the slags in a production process, has been undertaken. Main variables considered are concentrations of nitric acid, temperature, etc. Likewise, and acording to the attack variables the slags slurries filtration ...

A. Rodrigo Otero F. Rodrigo Vilaseca G. Morales J. Menendez

1976-01-01

303

Removal of molybdenum from uranium solutions  

Microsoft Academic Search

Molybdenum is removed from a uranium bearing alkaline carbonate leach solution, by adding a compound which provides lead ion to react with the molybdenum present to form insoluble lead molybdate (PbMoO) which precipitates from the solution.

1982-01-01

304

Lung cancer among Navajo uranium miners  

SciTech Connect

Lung cancer has been a rare disease among the Indians of the southwestern United States. However, the advent of uranium mining in the area has been associated with an increased incidence of lung cancer among Navajo uranium miners. This study centers on Navajo men with lung cancer who were admitted to the hospital from February 1965 to May 1979. Of a total of 17 patients with lung cancer, 16 were uranium miners, and one was a nonminer. The mean value of cumulative radon exposure for this group was 1139.5 working level months (WLMs). The predominant cancer type was the small cell undifferentiated category (62.5 percent). The low frequency of cigarette smoking in this group supports the view that radiation is the primary cause of lung cancer among uranium miners and that cigarette smoking acts as a promoting agent.

Gottlieb, L.S.; Husen, L.A.

1982-04-01

305

Uranium in aqueous solutions by colorimetry  

SciTech Connect

The method covers the quantitative determination of uranium in known volumes of aqueous solutions that contain radioactive nuclides. These solutions arise from processing of irradiated nuclear fuel and from laboratory studies on irradiated uranium. The method is applicable to solutions containing a minimum of 30 ..mu..g of uranium per sample although as little as 0.5 ..mu..g can be detected but with lower precision. Highest precision is obtained with 50 to 75 ..mu..g of uranium in the test sample. Dilutions must be made at concentrations above 750 ..mu..g/ml. The method includes a discussion of photometers and photometric practice, apparatus, reagents, cell matching, preparation of standard curves, calibration by the method of internal standards, procedure, calculation, and precision. (JMT)

Not Available

1981-01-01

306

Blood-Brain Barrier Transport of Uranium.  

National Technical Information Service (NTIS)

Recent studies of Gulf War veterans with depleted uranium (DU) embedded fragments in their soft tissues point to DU-induced effects on neurobehavioral and cognitive function. These observations are corroborated by electrophysiological changes in hippocamp...

M. Aschner

2005-01-01

307

Process for reducing beta activity in uranium  

DOEpatents

This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

Briggs, Gifford G. (Cincinnatti, OH); Kato, Takeo R. (Cincinnatti, OH); Schonegg, Edward (Cleves, OH)

1986-01-01

308

Uranium Geochemical Exploration in Northwestern Luzon.  

National Technical Information Service (NTIS)

A reconnaissance geochemical stream water and sediment survey which was conducted in northwestern Luzon was able to detect ten uranium anomalous areas. These anomalous areas are located along a north-south trending zone of Miocene marine clastics and sedi...

G. Santos L. Fernandez M. Ogena G. Tauli

1980-01-01

309

Recovery of Uranium from Refractory Ores.  

National Technical Information Service (NTIS)

Uranium is recovered from refractory carbonaceous-sulfidic ores or concentrates by leaching with nitric acid, followed by sorption on an ion exchange resin. In addition, the nitric acid leach solution is regenerated and recycled.

T. G. Carnahan K. P. V. Lei

1977-01-01

310

Spectrographic Determination of Microconstituents in Uranium Tetrafluoride.  

National Technical Information Service (NTIS)

A espectrographic method for the direct determination of impurities in uranium tetrafluoride (UF sub 4 ) was developed. The major impurities introduced during the preparation of UF sub 4 (Fe, Ni, Cr) and other impurities introduced in the prior stages of ...

L. C. Paula Reino A. R. Lordello

1982-01-01

311

BTD Building Uranium Mass Balance Study.  

National Technical Information Service (NTIS)

Fifteen test firings of depleted uranium (DU) munitions were made during the qualification study of the new target building at the BTD Range operated by the US Army Combat Systems Test Activity (CSTA) at Aberdeen Proving Ground, Maryland. Following these ...

S. L. Sutter J. W. Johnston J. A. Glissmeyer G. F. Athey

1985-01-01

312

Uranium enrichment activities: the SILVA program.  

National Technical Information Service (NTIS)

Through its commitment to a nuclear electricity generation policy, France holds today a specific position in the uranium enrichment market thanks to the modern multinational EURODIF gaseous diffusion plant. France has, altogether, a long-term goal in deve...

J. Guyot J. Cazalet N. Camarcat J. Figuet

1994-01-01

313

Neurotoxicity From Chronic Exposure to Depleted Uranium.  

National Technical Information Service (NTIS)

This project is designed to test the hypothesis that chronic exposure to depleted uranium (DU) impairs neuronal processes underlying cognitive function via alterations induced at hippocampal glutamatergic synapses As prescribed by the Statement of Work, e...

S. M. Lasley

2005-01-01

314

Process for reducing beta activity in uranium  

DOEpatents

This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

Briggs, G.G.; Kato, T.R.; Schonegg, E.

1985-04-11

315

Uranium-Mill-Tailings Conditioning Technology.  

National Technical Information Service (NTIS)

Conditioning of uranium mill tailings involves the physico-chemical alteration of tailings to remove or immobilize mobile radionuclides and toxic trace elements before disposal in a repository. The principal immobilization approach under investigation is ...

D. R. Dreesen E. J. Cokal P. D. O'Brien E. F. Thode L. E. Wangen

1982-01-01

316

Biodegradation of Uranium-Contaminated Waste Oil.  

National Technical Information Service (NTIS)

The Portsmouth Gaseous Diffusion Plant routinely generates quantities of uranium-contaminated waste oil. The current generation rate of waste oil is approximately 2000 gallons per year. The waste is presently biodegraded by landfarming on open field soil ...

L. F. Hary

1983-01-01

317

Engineering Assessment of Inactive Uranium Mill Tailings.  

National Technical Information Service (NTIS)

The Grand Junction site has been reevaluated in order to revise the October 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Grand Junction, Colorado. This engineering assessment has included...

1981-01-01

318

Tree Growth Studies on Uranium Mill Tailings.  

National Technical Information Service (NTIS)

Coniferous trees planted in 1974 and deciduous species, that have volunteered since 1970 on uranium mill tailings that had been stabilized to varying degrees using limestone and vegetation, were evaluated. Their survival and growth rates were compared wit...

D. R. Murray M. Turcotte

1982-01-01

319

All-Metal Uranium Bed Loading System.  

National Technical Information Service (NTIS)

The uranium bed processing system is essentially a vacuum system designed to transfer tritium gas from a large shipping container into small, portable containers called beds. The portable beds, designed to contain specific amounts of tritium or deuterium ...

C. C. Eichman

1979-01-01

320

Dynamic Response of High Temperature Uranium Phases  

Microsoft Academic Search

Unalloyed uranium and uranium-0.78 wt%Ti alloy were studied in planar impact experiments with initial sample temperature ranging from 27 to 860C. The velocity of the free surface of the samples was monitored by VISAR. It was found that the dynamic compressive strength of both the materials undergoes two-fold increase in the narrow temperature interval corresponding to the domain of beta-phase

E. Zaretsky; B. Herrmann; D. Shvarts

2006-01-01

321

BIOREMEDIATION OF URANIUM CONTAMINATED SOILS AND WASTES.  

SciTech Connect

Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (i) stabilization of uranium and toxic metals with reduction in waste volume and (ii) removal and recovery of uranium and toxic metals from wastes and contaminated soils. Stabilization of uranium and toxic metals in wastes is accomplished by exploiting the unique metabolic capabilities of the anaerobic bacterium, Clostridium sp. The radionuclides and toxic metals are solubilized by the bacteria directly by enzymatic reductive dissolution, or indirectly due to the production of organic acid metabolites. The radionuclides and toxic metals released into solution are immobilized by enzymatic reductive precipitation, biosorption and redistribution with stable mineral phases in the waste. Non-hazardous bulk components of the waste such as Ca, Fe, K, Mg and Na released into solution are removed, thus reducing the waste volume. In the second process uranium and toxic metals are removed from wastes or contaminated soils by extracting with the complexing agent citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, followed by photochemical degradation of the uranium citrate complex which is recalcitrant to biodegradation. The toxic metals and uranium are recovered in separate fractions for recycling or for disposal. The use of combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in clean-up and disposal costs.

FRANCIS,A.J.

1998-09-17

322

Uranium Sorption from Sulfate Solutions with Polyampholytes  

Microsoft Academic Search

Sorption of uranium from sulfate solutions with amino carboxylic, amino phosphonic poly-ampholytes was studied in relation to the pH and concentrations of sulfuric acid, ammonium sulfate, and themetal. The sorption is satisfactorily described by the equation Kd = KCeZ, similar to the Freundlich isotherm equation. The mechanism of uranium sorption on ampholytes is suggested on the basis of calculated data

V. N. Rychkov

2003-01-01

323

Depleted uranium: A DOE management guide  

SciTech Connect

The U.S. Department of Energy (DOE) has a management challenge and financial liability in the form of 50,000 cylinders containing 555,000 metric tons of depleted uranium hexafluoride (UF{sub 6}) that are stored at the gaseous diffusion plants. The annual storage and maintenance cost is approximately $10 million. This report summarizes several studies undertaken by the DOE Office of Technology Development (OTD) to evaluate options for long-term depleted uranium management. Based on studies conducted to date, the most likely use of the depleted uranium is for shielding of spent nuclear fuel (SNF) or vitrified high-level waste (HLW) containers. The alternative to finding a use for the depleted uranium is disposal as a radioactive waste. Estimated disposal costs, utilizing existing technologies, range between $3.8 and $11.3 billion, depending on factors such as applicability of the Resource Conservation and Recovery Act (RCRA) and the location of the disposal site. The cost of recycling the depleted uranium in a concrete based shielding in SNF/HLW containers, although substantial, is comparable to or less than the cost of disposal. Consequently, the case can be made that if DOE invests in developing depleted uranium shielded containers instead of disposal, a long-term solution to the UF{sub 6} problem is attained at comparable or lower cost than disposal as a waste. Two concepts for depleted uranium storage casks were considered in these studies. The first is based on standard fabrication concepts previously developed for depleted uranium metal. The second converts the UF{sub 6} to an oxide aggregate that is used in concrete to make dry storage casks.

NONE

1995-10-01

324

Uranium induces apoptosis in lung epithelial cells  

Microsoft Academic Search

Uranium is a naturally occurring radioactive material present everywhere in the environment. It is toxic because of its chemical\\u000a or radioactive properties. Uranium enters environment mainly from mines and industry and cause threat to human health by accumulating\\u000a in lungs as a result of inhalation. In our previous study, we have shown the effectiveness of antioxidant system response\\u000a to the

Adaikkappan Periyakaruppan; Shubhashish Sarkar; Prabakaran Ravichandran; Bindu Sadanandan; Chidananda S. Sharma; Vani Ramesh; Joseph C. Hall; Renard Thomas; Bobby L. Wilson; Govindarajan T. Ramesh

2009-01-01

325

Radium226 in uranium mill tailings  

Microsoft Academic Search

A study of the physical state of226Ra in uranium mill tailings was undertaken by Chemex Laboratories Ltd. under contract to NUTP. A test portion of a leached uranium ore was collected just prior to neutralization with lime and subjected to repetitive batch water leaching. The leachates were analyzed for barium, lead,226Ra, iron and sulphate. The experimental results suggest that226Ra is

H. F. Steger; M. Legeyt

1987-01-01

326

Conversion and Blending Facility Highly enriched uranium to low enriched uranium as uranium hexafluoride. Revision 1  

SciTech Connect

This report describes the Conversion and Blending Facility (CBF) which will have two missions: (1) convert surplus HEU materials to pure HEU UF{sub 6} and a (2) blend the pure HEU UF{sub 6} with diluent UF{sub 6} to produce LWR grade LEU-UF{sub 6}. The primary emphasis of this blending be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. The chemical and isotopic concentrations of the blended LEU product will be held within the specifications required for LWR fuel. The blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry.

NONE

1995-07-05

327

Physical characteristics and solubility of long-lived airborne particulates in uranium producing and manufacturing facilities Phase IV - Part II.  

National Technical Information Service (NTIS)

The rates of dissolution in simulated lung fluid of uranium dusts associated with three yellowcake processing areas at the Blind River Mill in Ontario and from uranium dioxide powder produced by a fluid bed process at Port Hope, Ontario were determined. B...

D. C. Stuart R. Robertson

1995-01-01

328

Permitting and licensing new uranium recovery facilities  

SciTech Connect

With the nuclear renaissance, the uranium mining industry has undergone a dramatic renaissance, as well. This was evidenced with the 2006 National Mining Association (NMA)/Nuclear Regulatory Commission (NRC) workshop drawing its largest attendance ever, with more than 180 attendees representing both established, as well as many new junior firms. And the meeting focused, not on site closure - but on the growing industry and plans for permitting new uranium recovery facilities. With this, the program provided overviews of the programs for permitting and licensing new uranium mines, from both the State and Federal perspectives. A subsequent one-day licensing workshop presented in February 2007 by NRC at its headquarters in Rockville, Maryland drew a crowd of experienced and first-time license applicants. Modern uranium mining is both safer and more environmentally protective than past practices - due largely to the industry's maturing and continuous efforts to improve. This paper will look at the new generation of uranium mining and recovery facilities that are developing in the US, and focus primarily on US permitting and licensing requirements and trends. Understanding these trends is essential to ensuring a vibrant US uranium recovery industry; assured supplies of this important fuel for our energy and the US economy; and environmental protection. (authors)

Rehmann, M. [Tetra Tech EM, Inc., Breckenridge, Colorado (United States); Sweeney, K. [National Mining Association, Washington, DC (United States); Pugsley, C. [Thompson and Simmons, Washington DC (United States)

2007-07-01

329

Microbial transformation of uranium in wastes  

SciTech Connect

Contamination of soils, water, and sediments by radionuclides and toxic metals from the disposal of uranium processing wastes is a major national concern. Although much is known about the physico- chemical aspects of U, we have little information on the effects of aerobic and anaerobic microbial activities on the mobilization or immobilization of U and other toxic metals in mixed wastes. In order to understand the mechanisms of microbial transformations of uranium, we examined a contaminated pond sediment and a sludge sample from the uranium processing facility at Y-12 Plant, Oak Ridge, TN. The uranium concentration in the sediment and sludge samples was 923 and 3080 ug/g dry wt, respectively. In addition to U, the sediment and sludge samples contained high levels of toxic metals such as Cd, Cr, Cu, Hg, Pb, Ni, and Zn. The association of uranium with the various mineral fractions of the sediment and sludge was determined by selective chemical extraction techniques. Uranium was associated to varying degrees with the exchangeable carbonate, iron oxide, organic, and inert fractions in both samples. Initial results in samples amended with carbon and nitrogen indicate immobilization of U due to enhanced indigenous microbial activity under anaerobic conditions. 23 refs., 4 figs., 5 tabs.

Francis, A.J.; Dodge, C.J.; Gillow, J.B.; Cline, J.E. (Brookhaven National Lab., Upton, NY (USA); Oak Ridge Y-12 Plant, TN (USA))

1989-01-01

330

The United States Uranium Industry, 1993  

SciTech Connect

Low prices and foreign competition continue to plague the United States uranium industry. For eight years (1984-1991) the Secretary of Energy has declared the industry to be nonviable. A similar declaration is expected late in 1993 for 1992. Surface drilling for uranium in 1993 is expected to be about 1 million ft., because deposits are developed prior to mining. Drilling for claim assessment purposes has ceased due to changes in the mining law. All conventional mining and milling in the United States ceased in early 1992 when the last open-pit mine closed. Underground mining ceased in late 1990. Current uranium production is from solution mining (in-situ leaching) in Wyoming, Texas, and Nebraska. Uranium is recovered from Florida phosphate rock processed in Louisiana and from mine water in New Mexico. Uranium concentrate production in 1993 is expected to be about 5 million lbs U[sub 3]O[sub 8]. The United States has large reserves of uranium, but a significant price increase is needed for the industry to rebound.

Chenoweth, W.L.

1993-08-01

331

Electrochemical method of producing eutectic uranium alloy and apparatus  

DOEpatents

An apparatus and method for continuous production of liquid uranium alloys through the electrolytic reduction of uranium chlorides. The apparatus includes an electrochemical cell formed from an anode shaped to form an electrolyte reservoir, a cathode comprising a metal, such as iron, capable of forming a eutectic uranium alloy having a melting point less than the melting point of pure uranium, and molten electrolyte in the reservoir comprising a chlorine or fluorine containing salt and uranium chloride. The method of the invention produces an eutectic uranium alloy by creating an electrolyte reservoir defined by a container comprising an anode, placing an electrolyte in the reservoir, the electrolyte comprising a chlorine or fluorine containing salt and uranium chloride in molten form, positioning a cathode in the reservoir where the cathode comprises a metal capable of forming an uranium alloy having a melting point less than the melting point of pure uranium, and applying a current between the cathode and the anode.

Horton, James A. (Livermore, CA); Hayden, H. Wayne (Oakridge, TN)

1995-01-01

332

Laser luminescence determination of uranium impurities in ThO/sub 2/  

SciTech Connect

The purpose of this work was to study the possibility of the direct luminescence determination of an admixture of uranium in thorium dioxide with the use of a crystal phosphor based on a 1:1 Na/sub 2/CO/sub 3/-NaF mixture, as well as to study the influence of some quenchers on the intensity of the luminescence of uranium.

Nikitina, S.A.; Aleksandruk, V.M.; Stepanov, A.V.

1988-01-01

333

Analytical laboratories method No. 4011 - radiometric determination of uranium-232 in uranium bearing materials  

SciTech Connect

The method is designed for use on recycled uranium materials and is applicable to materials that will yield at least 100 mg of uranium. Typical analysis time is 24 to 30 hours. U-232 can be measured to a lower limit of detection of 1 ppb (U-235 basis).

Not Available

1987-01-14

334

Maintaining the uranium resources data system and assessing the 1989 US uranium potential resources  

Microsoft Academic Search

Under the Memorandum of Understanding (MOU) between the EIA, US Department of Energy, and the US Geological Survey (USGS), US Department of the Interior, the USGS develops estimates of uranium endowment for selected geological environments in the United States. New estimates of endowment are used to update the Uranium Resources Assessment Data (URAD) System which, beginning in 1990, is maintained

R. B. McCammon; W. I. Finch; W. D. Grundy; C. T. Pierson

1990-01-01

335

Selective leaching of uranium from uranium-contaminated soils: Progress report 1  

Microsoft Academic Search

Three soils and a sediment contaminated with uranium were used to determine the effectiveness of sodium carbonate and citric acid leaching to decontaminated or remove uranium to acceptable regulatory levels. Two of the soils were surface soils from the DOE facility formerly called the Feed Materials Production Center (FMPC) at Fernald, Ohio. This facility is presently called the Femald Environmental

C. W. Francis; A. J. Mattus; L. L. Farr; M. P. Elless; S. Y. Lee

1993-01-01

336

A NEW METHOD BASED ON PAPER CHROMATOGRAPHY FOR THE DETERMINATION OF URANIUM IN URANIUM MINERALS  

Microsoft Academic Search

A titraiion using ethylenediaminetetraacetate for uranium determination ; is described. Xylenol orange is used as indicator, This method makes possible ; the separation of uranium from other constituents of its mineral by paper ; chromatography, and subsequeat determination via the EDTA titration. The method ; is fully described. (J.R.D.);

I. I. M. Elbeih; M. A. Abou-Elnaga

1958-01-01

337

Photoluminescence of uranium(VI): quenching mechanism and role of uranium(V).  

PubMed

The photoluminescence of uranium(VI) is observed typically in the wavelength range 400-650 nm with the lifetime of several hundreds mus and is known to be quenched in the presence of various halide ions (case A) or alcohols (case B). Here, we show by density functional theory (DFT) calculations that the quenching involves an intermediate triplet excited state that exhibits uranium(V) character. The DFT results are consistent with previous experimental findings suggesting the presence of photoexcited uranium(V) radical pair during the quenching process. In the ground state of uranyl(VI) halides, the ligand contributions to the highest occupied molecular orbitals increase with the atomic number (Z) of halide ion allowing larger ligand-to-metal charge transfer (LMCT) between uranium and the halide ion. Consequently, a larger quenching effect is expected as Z increases. The quenching mechanism is essentially the same in cases A and B, and is driven by an electron transfer from the quencher to the UO(2)(2+) entity. The relative energetic stabilities of the triplet excited state define the "fate" of uranium, so that in case A uranium(V) is oxidized back to uranium(VI), while in case B uranium remains as pentavalent. PMID:20533460

Tsushima, Satoru; Gtz, Christian; Fahmy, Karim

2010-07-19

338

An evaluation and revision of the gravimetric determination of uranium in uranium hexafluoride  

SciTech Connect

An evaluation of the indirect gravimetric determination of uranium in uranium hexafluoride has been made, and the accuracy has been established by comparison to a direct titration of uranium using potassium dichromate (SRM-136c). From this study the gravimetric method has been revised to increase accuracy. The revised method is biased less than 0.01 percent low as compared to 0.02 percent with the unrevised method. It was found that the gravimetric factor must be based on the stoichiometry of the U/sub 3/O/sub 8/ which varies with pyrohydrolysis conditions. The low bias was caused by volatilization loss of uranium as uranium hexafluoride during pyrohydrolysis and very small errors in the determination of the sample weight. Because of the volatilization loss the use of a bias correction factor with the revised method is justified. 5 refs., 7 tabs.

Vita, O.A.; Trivisonno, C.F.; Shoaf, R.E.

1982-01-26

339

Pulsed laser nitriding of uranium  

NASA Astrophysics Data System (ADS)

Pulsed laser nitriding offers several advantages such as high nitrogen concentration, low matrix temperature, fast treatment, simple vacuum chamber and precise position control compare to ion implantation, which is favorable for radioactive material passivation. In this work, uranium metal was nitrided using an excimer laser for the first time. The nitrided layers are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The nitride layer is composed mainly of UN and U 2N 3 and depends on nitriding process. The amount of nitride increases with energy density and pressure. The irradiated area has a wavy structure which increases the roughness, while scratches and asperities caused by sand paper polishing were eliminated. Scan speed has a profound influence on the nitride layer, at low speed U 2N 3 is more likely to form and the nitride layer tends to crack. XPS analysis shows that nitrogen has diffused into interior, while oxygen is only present on the surface. Ambient and humid-hot corrosion tests show the nitrided sample has good anticorrosion property.

Zhang, Yongbin; Meng, Daqiao; Xu, Qinying; Zhang, Youshou

2010-02-01

340

Atomistic Properties of Y Uranium  

SciTech Connect

The properties of the body-centered cubic y phase of uranium (U) are calculated using atomistic simulations. First, a modified embedded-atom method interatomic potential is developed for the high temperature body-centered cubic (y) phase of U. This phase is stable only at high temperatures and is thus relatively inaccessible to first principles calculations and room temperature experiments. Using this potential, equilibrium volume and elastic constants are calculated at 0 K and found to be in close agreement with previous first principles calculations. Further, the melting point, heat capacity, enthalpy of fusion, thermal expansion and volume change upon melting are calculated and found to be in reasonable agreement with experiment. The low temperature mechanical instability of y U is correctly predicted and investigated as a function of pressure. The mechanical instability is suppressed at pressures greater than 17.2 GPa. The vacancy formation energy is analyzed as a function of pressure and shows a linear trend, allowing for the calculation of the extrapolated zero pressure vacancy formation energy. Finally, the self-defect formation energy is analyzed as a function of temperature. This is the first atomistic y calculation of U properties above 0 K with interatomic potentials.

Benjamin Beeler; Chaitanya Deo; Mmichael Baskes; Maria Okuniewski

2012-02-01

341

Characterizing In Situ Uranium and Groundwater Flux  

NASA Astrophysics Data System (ADS)

The goal of this project is to develop a new sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of uranium and groundwater fluxes. The sensor uses two sorbents and resident tracers to measure uranium flux and specific discharge directly; but, sensor principles and design should also apply to fluxes of other radionuclides. Flux measurements will assist with obtaining field-scale quantification of subsurface processes affecting uranium transport (e.g., advection) and transformation (e.g., uranium attenuation) and further advance conceptual and computational models for field scale simulations. Project efforts will expand our current understanding of how field-scale spatial variations in uranium fluxes and those for salient electron donor/acceptors, and groundwater are coupled to spatial variations in measured microbial biomass/community composition, effective field-scale uranium mass balances, attenuation, and stability. The new sensor uses an anion exchange resin to measure uranium fluxes and activated carbon with resident tracers to measure water fluxes. Several anion-exchange resins including Dowex 21K and 21K XLT, Purolite A500, and Lewatit S6328 were tested as sorbents for capturing uranium on the sensor and Lewatit S6328 was determined to be the most effective over the widest pH range. Four branched alcohols proved useful as resident tracers for measuring groundwater flows using activated carbon for both laboratory and field conditions. The flux sensor was redesigned to prevent the discharge of tracers to the environment, and the new design was tested in laboratory box aquifers and the field. Geochemical modeling of equilibrium speciation using Visual Minteq and an up-to-date thermodynamic data base suggested Ca-tricarbonato-uranyl complexes predominate under field conditions, while calculated uranyl ion activities were sensitive to changes in pH, dissolved inorganic carbon (DIC) and alkaline earth metals. Initial field tests at the Rifle IFRC site were conducted to assess ambient groundwater and uranium fluxes, monitor microbial growth on the sensor during field deployment, and further resolve any unforeseen problems evolving from field deployment. Ten flux sensors were deployed in five wells for three weeks from mid-November to early December 2009. Observed water fluxes varied from 1.2 - 5.3 cm/d while uranium fluxes ranged from 0.01 - 2.2 ug/cm2d. Uranium and water flux variations corresponded closely with changes in lithology. Uranium fluxes were typically observed to increase with depth. Stochastic simulations were conducted to estimate the magnitude of uranium discharge over a 10.5 m2 transect. The mean discharge was approximately 52 mg/d with a narrow 90% confidence interval of 11%.

Cho, J.; Newman, M. A.; Stucker, V.; Peacock, A.; Ranville, J.; Cabaniss, S.; Hatfield, K.; Annable, M. D.; Klammler, H.; Perminova, I. V.

2010-12-01

342

Plutonium and uranium adsorption on monosodium titanate  

SciTech Connect

Adsorption of Pu and U onto monosodium titanate (MST) in alkaline salt solution was measured. Changes in MST particle size distribution do not significantly affect the loadings of actinides. Max loading of plutonium-239 is 0.68 wt% at 0.79 mg/L Pu, below the infinitely safe value of 0.80 wt%. Max loading of uranium-235 onto MST is 1.4 wt% at a concentration of 20.3 {plus_minus} 2.0 mg/L U, slightly higher than the calculated infinitely safe limit of 1.2 wt%. Experimental data indicated there is competition between plutonium and uranium for sites on the MST, and that the loading will favor the higher concentration species. Since the solubility of uranium is 10--100 times higher than of plutonium, uranium will be loaded to its maximum limit, but plutonium will be below its maximum limit. To ensure that the concentration of fissile materials cannot exceed nuclear safety limits, it is recommended that plutonium and uranium solubility tests be conducted with solutions which bound the compositions of waste which will be treated in ITP process.

Hobbs, D.T.; Walker, D.D.

1992-08-13

343

Plutonium and uranium adsorption on monosodium titanate  

SciTech Connect

Adsorption of Pu and U onto monosodium titanate (MST) in alkaline salt solution was measured. Changes in MST particle size distribution do not significantly affect the loadings of actinides. Max loading of plutonium-239 is 0.68 wt% at 0.79 mg/L Pu, below the infinitely safe value of 0.80 wt%. Max loading of uranium-235 onto MST is 1.4 wt% at a concentration of 20.3 [plus minus] 2.0 mg/L U, slightly higher than the calculated infinitely safe limit of 1.2 wt%. Experimental data indicated there is competition between plutonium and uranium for sites on the MST, and that the loading will favor the higher concentration species. Since the solubility of uranium is 10--100 times higher than of plutonium, uranium will be loaded to its maximum limit, but plutonium will be below its maximum limit. To ensure that the concentration of fissile materials cannot exceed nuclear safety limits, it is recommended that plutonium and uranium solubility tests be conducted with solutions which bound the compositions of waste which will be treated in ITP process.

Hobbs, D.T.; Walker, D.D.

1992-08-13

344

Uranium soils integrated demonstration, 1993 status  

SciTech Connect

The Fernald Environmental Management Project (FEMP), operated by the Fernald Environmental Restoration Management Corporation (FERMCO) for the DOE, was selected as the host site for the Uranium Soils Integrated Demonstration. The Uranium Soils ID was established to develop and demonstrate innovative remediation methods which address the cradle to grave elements involved in the remediation of soils contaminated with radionuclides, principally uranium. The participants in the ID are from FERMCO as well as over 15 other organizations from DOE, private industry and universities. Some of the organizations are technology providers while others are members of the technical support groups which were formed to provide technical reviews, recommendations and labor. The following six Technical Support Groups (TSGs) were formed to focus on the objective of the ID: Characterization, Excavation, Decontamination, Waste Treatment/Disposal, Regulatory, and Performance Assessment. This paper will discuss the technical achievements made to date in the program as well as the future program plans. The focus will be on the realtime analysis devices being developed and demonstrated, the approach used to characterize the physical/chemical properties of the uranium waste form in the soil and lab scale studies on methods to remove the uranium from the soil.

Nuhfer, K.

1994-08-01

345

Calixarene cleansing formulation for uranium skin contamination.  

PubMed

An oil-in-water cleansing emulsion containing calixarene molecule, an actinide specific chelating agent, was formulated in order to improve the decontamination of uranium from the skin. Commonly commercialized cosmetic ingredients such as surfactants, mineral oil, or viscosifying agents were used in preparing the calixarene emulsion. The formulation was characterized in terms of size and apparent viscosity measurements and then was tested for its ability to limit uranyl ion permeation through excoriated pig-ear skin explants in 24-h penetration studies. Calixarene emulsion effectiveness was compared with two other reference treatments consisting of DTPA and EHBP solutions. Application of calixarene emulsion induced the highest decontamination effect with an 87% decrease in uranium diffusion flux. By contrast, EHBP and DTPA solutions only allowed a 50% and 55% reduction of uranium permeation, respectively, and had the same effect as a simple dilution of the contamination by pure water. Uranium diffusion decrease was attributed to uranyl ion-specific chelation by calixarene within the formulation, since no significant effect was obtained after application of the same emulsion without calixarene. Thus, calixarene cleansing emulsion could be considered as a promising treatment in case of accidental contamination of the skin by highly diffusible uranium compounds. PMID:23982616

Phan, Guillaume; Semili, Nama; Bouvier-Capely, Cline; Landon, Graldine; Mekhloufi, Ghozlene; Huang, Nicolas; Rebire, Franois; Agarande, Michelle; Fattal, Elias

2013-10-01

346

Uranium binding by emulsan and emulsanosols.  

PubMed

Emulsan, the extracellular bioemulsifier of Acinetobacter RAG-1, bound up to 0.9 microm of uranium per 1 mg emulsan. The dissociation constant for the emulsan-uranium complex, K(app) (I) was 1.2 x 10(-4)M. Much larger amounts of uranium were bound to emulsan when the biopolymer occurred on hexadecane-water interfaces. Under these conditions, more than 3.5 microm uranium were bound per 1 mg emulsan and the dissociation constant K(app) (II) was 5.1 x 10(-5)M. At pH 2, more than 90% of the uranium bound to emulsan on the hexadecane-water interface was desorbed, while less than 10% bioemulsifier was released from the interface. The different binding parameters of emulsan when free in solution and while adsorbed onto the hexadecane water interface are discussed in view of potential applications and as a model system for studying the properties of an extracellular amphipathic polymer bound to a hydrophobic surface. PMID:18551477

Zosim, Z; Gutnick, D; Rosenberg, E

1983-07-01

347

Search for uranium in western United States  

USGS Publications Warehouse

The search for uranium in the United States is one of the most intensive ever made for any metal during our history. The number of prospectors and miners involved is difficult to estimate but some measure of the size of the effort is indicated by the fact that about 500 geologists are employed by government and industry in the work--more than the total number of geologists engaged in the study of all other minerals together except oil. The largest part of the effort has been concentrated in the western states. No single deposit of major importance by world standards has been discovered but the search has led to the discovery of important minable deposits of carnotite and related minerals on the Colorado Plateau; of large, low grade deposits of uranium in phosphates in the northwestern states and in lignites in the Dakotas, Wyoming, Idaho and New Mexico; and of many new and some promising occurrences of uranium in carnotite-like deposits and in vein deposits. Despite the fact that a large number of the districts considered favorable for the occurrence of uranium have already been examined, the outlook for future discoveries is bright, particularly for uranium in vein and in carnotite-like deposits in the Rocky Mountain States.

McKelvey, Vincent Ellis

1953-01-01

348

RESOLUTION OF URANIUM ISOTOPES WITH KINETIC PHOSPHORESCENCE ANALYSIS  

SciTech Connect

This study was conducted to test the ability of the Chemchek Kinetic Phosphorescence Analyzer Model KPA-11 with an auto-sampler to resolve the difference in phosphorescent decay rates of several different uranium isotopes, and therefore identify the uranium isotope ratios present in a sample. Kinetic phosphorescence analysis (KPA) is a technique that provides rapid, accurate, and precise determination of uranium concentration in aqueous solutions. Utilizing a pulsed-laser source to excite an aqueous solution of uranium, this technique measures the phosphorescent emission intensity over time to determine the phosphorescence decay profile. The phosphorescence intensity at the onset of decay is proportional to the uranium concentration in the sample. Calibration with uranium standards results in the accurate determination of actual concentration of the sample. Different isotopes of uranium, however, have unique properties which should result in different phosphorescence decay rates seen via KPA. Results show that a KPA is capable of resolving uranium isotopes.

Miley, Sarah M.; Hylden, Anne T.; Friese, Judah I.

2013-04-01

349

National Uranium Resource Evaluation: Klamath Falls Quadrangle, Oregon and California.  

National Technical Information Service (NTIS)

The Klamath Falls Quadrangle, Oregon, was evaluated to identify and delineate areas favorable for uranium deposits according to criteria developed for the National Uranium Resource Evaluation. Surface radiometric reconnaissance and geochemical sampling we...

S. B. Castor M. R. Berry J. W. Robins

1982-01-01

350

Epidemiologic Studies to Evaluate Health Effects of Uranium Milling.  

National Technical Information Service (NTIS)

The overall goals of this research effort are to test whether chronic respiratory and renal effects are associated with exposures to silica and uranium dusts in former uranium mill workers. These objectives are congruent with the directives of the United ...

W. E. Lambert

2002-01-01

351

Distribution of uranium in mice using the fission track technique  

NASA Astrophysics Data System (ADS)

Four groups of mice were dissected at various time intervals from 0.5 to 144 hours after their intravenous injection of uranium. The uranium distribution and deposition in the tissues of kidney, lung, marrow, liver, heart, muscle and blood have been studied using the fission track technique (FTT). Our experimental results show that trace uranium is more likely to be deposited in kidneys and lungs than in marrow and liver. The presence of uranium in the blood is so transient that blood-uranium level cannot be used to estimate the degree of the storage of uranium in the body. However, the mice injected with high dose uranium die soon because the uranium poisons the heart severely.

Yulin, Cheng; Junying, Lin; Jiong, Zhang; Guaofu, Liu; Liping, Zheng; Xiaoyu, Cheng; Xiuhong, Hao

1992-09-01

352

Investigation of the Relationship Between Organic Matter and Uranium Deposits.  

National Technical Information Service (NTIS)

Topical literature and the initial results of investigations on the relationship between organic matter and uranium ore formation are summarized. Primary emphasis is focused on the investigation of humic and fulvic acids and their uranium complexes as the...

J. J. Schmidt-Collerus

1978-01-01

353

Cancer Epidemiology in Respiratory System among Uranium Miners.  

National Technical Information Service (NTIS)

A summary of some published papers about cancer in the respiratory system among uranium miners is presented. A comparative table relating cancer cases among uranium miners is shown. A table relating cases among miners in Czechoslovakia and cumulative expo...

A. Moraes

1976-01-01

354

Uranium in Hot Water Tanks: A Source of Tenorm.  

National Technical Information Service (NTIS)

Elevated concentrations of uranium have been detected in private drinking water wells of residents near Simpsonville, South Carolina. Elevated levels of uranium were first detected by private sampling at one home in Simpsonville in January 2001. A member ...

R. L. Woodruff

2002-01-01

355

Reducing the environmental impact of uranium in-situ recovery.  

SciTech Connect

This session will explore the current technical approaches to reducing the environmental effects of uranium ISR in comparison to the historical environmental impact of uranium mining to demonstrate advances in this controversial subject.

Siegel, Malcolm Dean; Simmons, Ardyth

2010-10-01

356

What Price Energy? Hazards of Uranium Mining in the Southwest.  

ERIC Educational Resources Information Center

This article describes the hazards, sickness, death and destruction caused by uranium mining/nuclear energy development in the Southwest focusing on the experiences of several Indian uranium mines. (RTS)

Barry, Tom

1979-01-01

357

Influence of Uranium on Bacterial Communities: A Comparison of Natural Uranium-Rich Soils with Controls  

PubMed Central

This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil.

Mondani, Laure; Benzerara, Karim; Carriere, Marie; Christen, Richard; Mamindy-Pajany, Yannick; Fevrier, Laureline; Marmier, Nicolas; Achouak, Wafa; Nardoux, Pascal; Berthomieu, Catherine; Chapon, Virginie

2011-01-01

358

Uranium geochemistry on the Amazon shelf: Evidence for uranium release from bottom sediments  

SciTech Connect

In Amazon-shelf waters, as salinity increases to 36.5 x 10{sup {minus}3}, dissolved uranium activities increase to a maximum of 4.60 dpm 1{sup {minus}1}. This value is much higher than the open-ocean value (2.50 dpm 1{sup {minus}1}), indicating a source of dissolved uranium to shelf waters in addition to that supplied from open-ocean and riverine waters. Uranium activities are much lower for surface sediments in the Amazon-shelf sea bed (mean: 0.69 {plus minus} .09 dpm g{sup {minus}1}) than for suspended sediments in the Amazon river (1.82 dpm g{sup {minus}1}). Data suggest that the loss of particulate uranium from riverine sediments is probably the result of uranium desorption from the ferric-oxyhydroxide coatings on sediment particles, and/or uranium release by mobilization of the ferric oxyhydroxides. The total flux of dissolved {sup 238}U from the Amazon shelf (about 1.2 x 10{sup 15} dpm yr{sup {minus}1}) constitutes about 15% of uranium input to the world ocean, commensurate to the Amazon River's contribution to world river-water discharge. Measurement of only the riverine flux of dissolved {sup 238}U underestimates, by a factor of about 5, the flux of dissolved {sup 238}U from the Amazon shelf to the open ocean.

McKee, B.A.; DeMaster, D.J.; Nittrouer, C.A. (North Carolina State Univ., Raleigh (USA))

1987-10-01

359

Uranium and thorium solubilities in subduction zone fluids  

Microsoft Academic Search

Uranium is enriched in depleted island arc magmas more than would be anticipated, due to the overall enrichment in large ion lithophile elements. To attempt to understand this enrichment calculations were performed to establish concentrations of uranium and thorium in fluids under the pressure and temperatures experienced in a subduction zone. The solubility and speciation of uranium(VI), uranium(IV) and thorium(IV)

Elizabeth H. Bailey; K. Vala Ragnarsdottir

1994-01-01

360

ToF-SIMS characterization of uranium hydride  

Microsoft Academic Search

Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) has been employed for the first time to investigate uranium hydride. The deuterated form of uranium hydride (UD3) was formed on a polycrystalline uranium sample by exposure to high-purity D2 gas at room temperature. The characteristic positive and negative secondary-ion fragments observed from uranium hydride are reported and assigned. Our investigations show that negative-ion fragments

P. Morrall; D. W. Price; A. J. Nelson; W. J. Siekhaus; E. Nelson; K. J. Wu; M. Stratman; W. McLean II

2007-01-01

361

Retrieval of buried depleted uranium from the T-1 trench  

SciTech Connect

The Trench 1 remediation project will be conducted this year to retrieve depleted uranium and other associated materials from a trench at Rocky Flats Environmental Technology Site. The excavated materials will be segregated and stabilized for shipment. The depleted uranium will be treated at an offsite facility which utilizes a novel approach for waste minimization and disposal through utilization of a combination of uranium recycling and volume efficient uranium stabilization.

Burmeister, M. [Rocky Mountain Remediation Services, Golden, CO (United States); Castaneda, N. [Dept. of Energy, Golden, CO (United States). Rocky Flats Field Office; Greengard, T. [Kaiser-Hill Co., Golden, CO (United States)]|[Science Applications International Corp. (United States); Hull, C. [S.M. Stoller Corp., Boulder, CO (United States); Barbour, D.; Quapp, W.J. [Starmet Corp. (United States)

1998-07-01

362

Uranium internal exposure evaluation based on urine assay data  

SciTech Connect

The difficulties in assessing internal exposures to uranium from urine assay data are described. A simplified application of the ICRP-30 and ICRP Lung Model concepts to the estimation of uranium intake is presented. A discussion follows on the development of a computer code utilizing the ICRP-30-based uranium elimination model with the existing urine assay information. The calculated uranium exposures from 1949 through 1983 are discussed. 13 references, 1 table.

Lawrence, J.N.P.

1984-09-01

363

Postirradiation examination of higher uranium density fuels at JAERI  

Microsoft Academic Search

A reduced enrichment program for research and test reactor fuels at Japan Atomic Energy Research Institute (JAERI), in which the JRR-2 and Japan Material Testing Reactor (JMTR) are to be converted to the use of medium-enriched uranium (MEU) (45% enriched uranium) aluminide fuels and the JRR-3 and JRR-4 to the use of low-enriched uranium (LEU) (19.5% enriched uranium) aluminide fuels

Y. Futamura; A. Yamamoto; E. Shirai; R. Oyamada; M. Saito; M. Adachi; H. Sakai

1987-01-01

364

The Dissolution of Uranium Oxides in HB-Line Phase 1 Dissolvers  

SciTech Connect

A series of characterization and dissolution studies has been performed to define flowsheet conditions for the dissolution of uranium oxide materials in dissolvers. The samples selected for analysis were uranium oxide materials. The selection of these uranium oxide materials for characterization and dissolution studies was based on high enriched uranium content and trace levels of plutonium. Test results from the characterization study identified ferric oxide (Fe2O3) and iron/chromium/nickel (Fe/Cr/Ni) particles as impurities along with the tri-uranium oxide (U3O8) and uranium trioxide (UO3). The weight percent uranium in this material was found to vary depending on the impurity content. The trace impurity plutonium appears to be associated with the Fe/Cr/Ni particles. A small amount of absorbed moisture and waters of hydration is present. Most of the uranium oxides easily dissolved in low-molar nitric acid solutions without fluoride within one to two hours at solution temperature s between 60-80 degrees C. A small amount of residue remained following this dissolution step. To assure complete dissolution of uranium from these oxide materials, an additional dissolution step at 90 degrees C to boiling for at least one to two hours has been suggested. Only trace amounts of iron associated with Fe2O3 and Fe/Cr/Ni particles will dissolve during the dissolution steps. Neither hydrogen nor heat will be generated during the dissolution of these uranium oxide materials in nitric acid solutions. Some brown nitrogen dioxide (NO2) fumes will be generated during the dissolution of U3O8.

Gray, J.H.

2003-08-28

365

Decontamination of uranium-contaminated steel surfaces by hydroxycarboxylic acid with uranium recovery.  

PubMed

We developed a simple, safe method to remove uranium from contaminated metallic surfaces so that the materials can be recycled or disposed of as low-level radioactive or nonradioactive waste. Surface analysis of rusted uranium-contaminated plain carbon-steel coupons by X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy showed that uranium was predominantly associated with ferrihydrite, lepidocrocite, and magnetite, or occluded in the matrix of the corrosion product as uranyl hydroxide and schoepite (UO3 x 2H2O). Citric acid formulations, consisting of oxalic acid-hydrogen peroxidecitric acid (OPC) or citric acid-hydrogen peroxidecitric acid (CPC), were used to remove uranium from the coupons. The efficiency of uranium removal varied from 68% to 94% depending on the extent of corrosion, the association of uranium with the iron oxide matrix, and the accessibility of the occluded contaminant. Decontaminated coupons clearly showed evidence of the extensive removal of rust and uranium. The waste solutions containing uranium and iron from decontamination by OPC and CPC were treated first by subjecting them to biodegradation followed by photodegradation. Biodegradation of a CPC solution by Pseudomonas fluorescens resulted in the degradation of the citric acid with concomitant precipitation of Fe (>96%), whereas U that remained in solution was recovered (>99%) by photodegradation as schoepite. In contrast, in an OPC solution citric acid was biodegraded but not oxalic acid, and both Fe and U remained in solution. Photodegradation of this OPC solution resulted in the precipitation of iron as ferrihydrite and uranium as uranyl hydroxide. PMID:16053105

Francis, A J; Dodge, C J; McDonald, J A; Halada, G P

2005-07-01

366

Health concerns in uranium mining and milling  

SciTech Connect

Mortality of uranium miners from both lung cancer and other respiratory diseases is strongly dependent on exposure to radon daughters, cigarette smoking and height. Lung cancer among 15 different mining groups (uranium, iron, lead, zinc) was analyzed to determine what factors influence incidence and the induction-latent period. At low exposure or exposure rates, alpha radiation is more efficient in inducing lung cancer, producing an upward convex exposure-response curve. The induction-latent period is shortened by increased age at start of mining, by cigarette smoking and by high exposure rates. Instead of extrapolating downward from high exposures to estimate risk at low levels, it is suggested that it might be more appropriate to use cancer rates associated with background radiation as the lowest point on the exposure-response curve. Although health risks are much greater in uranium mines than mills, there is some health risk in the mills from long-lived radioactive materials.

Archer, V.E.

1981-07-01

367

Depleted uranium plasma reduction system study  

SciTech Connect

A system life-cycle cost study was conducted of a preliminary design concept for a plasma reduction process for converting depleted uranium to uranium metal and anhydrous HF. The plasma-based process is expected to offer significant economic and environmental advantages over present technology. Depleted Uranium is currently stored in the form of solid UF{sub 6}, of which approximately 575,000 metric tons is stored at three locations in the U.S. The proposed system is preconceptual in nature, but includes all necessary processing equipment and facilities to perform the process. The study has identified total processing cost of approximately $3.00/kg of UF{sub 6} processed. Based on the results of this study, the development of a laboratory-scale system (1 kg/h throughput of UF6) is warranted. Further scaling of the process to pilot scale will be determined after laboratory testing is complete.

Rekemeyer, P.; Feizollahi, F.; Quapp, W.J.; Brown, B.W.

1994-12-01

368

Monitoring genotoxic exposure in uranium mines  

SciTech Connect

Recent data from deep uranium mines in Czechoslovakia indicated that miners are exposed to other mutagenic factors in addition to radon daughter products. Mycotoxins were identified as a possible source of mutagens in these mines. Mycotoxins were examined in 38 samples from mines and in throat swabs taken from 116 miners and 78 controls. The following mycotoxins were identified from mines samples: aflatoxins B{sub 1} and G1, citrinin, citreoviridin, mycophenolic acid, and sterigmatocystin. Some mold strains isolated from mines and throat swabs were investigated for mutagenic activity by the SOS chromotest and Salmonella assay with strains TA100 and TA98. Mutagenicity was observed, especially with metabolic activation in citro. These data suggest that mycotoxins produced by molds in uranium mines are a new genotoxic factor im uranium miners. 17 refs., 4 tabs.

Sram, R.J.; Vesela, D.; Vesely, D. [Institute of Experimental Medicine, Prague (Czech Republic)] [and others

1993-10-01

369

Plutonium recovery from spent reactor fuel by uranium displacement  

DOEpatents

A process for separating uranium values and transuranic values from fission products containing rare earth values when the values are contained together in a molten chloride salt electrolyte. A molten chloride salt electrolyte with a first ratio of plutonium chloride to uranium chloride is contacted with both a solid cathode and an anode having values of uranium and fission products including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is reestablished.

Ackerman, John P. (Downers Grove, IL)

1992-01-01

370

Electrokinetic removal of uranium from contaminated, unsaturated soils  

SciTech Connect

Electrokinetic remediation of uranium-contaminated soil was studied in a series of laboratory-scale experiments in test cells with identical geometry using quartz sand at approximately 10 percent moisture content. Uranium, when present in the soil system as an anionic complex, could be migrated through unsaturated soil using electrokinetics. The distance that the uranium migrated in the test cell was dependent upon the initial molar ratio of citrate to uranium used. Over 50 percent of the uranium was recovered from the test cells using the citrate and carbonate complexing agents over of period of 15 days. Soil analyses showed that the uranium remaining in the test cells had been mobilized and ultimately would have been extracted. Uranium extraction exceeded 90 percent in an experiment that was operated for 37 days. Over 70 percent of the uranium was removed from a Hanford waste sample over a 55 day operating period. Citrate and carbonate ligand utilization ratios required for removing 50 percent of the uranium from the uranium-contaminated sand systems were approximately 230 moles ligand per mole uranium and 1320 moles ligand per mole uranium for the waste. Modifying the operating conditions to increasing the residence time of the complexants is expected to improved the utilization efficiency of the complexing agent.

Booher, W.F. [IT Corp., Albuquerque, NM (United States); Lindgren, E.R.; Brady, P.V. [Sandia National Laboratories, Albuquerque, NM (United States)

1997-01-01

371

National Uranium Resource Evaluation, Klamath Falls Quadrangle, Oregon and California  

SciTech Connect

The Klamath Falls Quadrangle, Oregon, was evaluated to identify and delineate areas favorable for uranium deposits according to criteria developed for the National Uranium Resource Evaluation. Surface radiometric reconnaissance and geochemical sampling were used for overall evaluation of the quadrangle. Detailed rock sampling, geologic mapping, and examinations of uranium mines and occurrences were performed in suspected favorable areas. Results of the work indicate good potential for shallow hydrothermal volcanogenic uranium deposits in the Lakeview favorable area, which comprises a northwest-trending belt of rhyolite intrusions in the eastern half of the quadrangle. The young age, peraluminous chemistry, and low thorium-to-uranium ratios of the rhyolite intrusions, as well as low uranium content of groundwater samples, indicate that uranium has not been leached from the intrusions by ground water. Therefore, supergene uranium deposits are not likely in the area. Scattered occurrences of ash-flow tuff in the east half of the quadrangle that contain high uranium and (or) thorium contents, and four occurrences of secondary uranium minerals in ash-flow tuff, indicate possible uranium deposits in ash flows in a poorly defined area that is partially coextensive with the Lakeview favorable area. Small granitic plutons with associated quartz-tourmaline breccia veins and base-metal occurrences may also be favorable for uranium deposits but were not examined during this study.

Castor, S.B.; Berry, M.R.; Robins, J.W.

1982-07-01

372

Occupational Exposures to Uranium: Processes, Hazards, and Regulations.  

National Technical Information Service (NTIS)

The United States Uranium Registry (USUR) was formed in 1978 to investigate potential hazards from occupational exposure to uranium and to assess the need for special health-related studies of uranium workers. This report provides a summary of Registry wo...

D. R. Fisher G. A. Stoetzel G. R. Hoenes S. Marks W. D. McCormack

1981-01-01

373

Plutonium recovery from spent reactor fuel by uranium displacement  

DOEpatents

A process is described for separating uranium values and transuranic values from fission products containing rare earth values when the values are contained together in a molten chloride salt electrolyte. A molten chloride salt electrolyte with a first ratio of plutonium chloride to uranium chloride is contacted with both a solid cathode and an anode having values of uranium and fission products including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is reestablished.

Ackerman, J.P.

1992-03-17

374

Uranium favorability of part of the Raleigh Quadrangle, North Carolina  

Microsoft Academic Search

Part of the Raleigh, North Carolina, 1° by 2° quadrangle was evaluated to identify geologic environments favorable for uranium. Tabular sandstone deposits may occur in the Triassic basins where the Cumnock Formation interfingers with the Sanford Formation. The uranium deposits may have formed where humic and fulvic acids were expelled from lacustrine sediments to form tabular humate deposits. Later, uranium

R. T. Chew; C. M. Hacke

1982-01-01

375

National Uranium Resource Evaluation: Lamar quadrangle, Colorado and Kansas  

Microsoft Academic Search

Uranium resources of the Lamar Quadrangle, Colorado and Kansas, were evaluated using National Uranium Resource Evaluation criteria. The environment favorable for uranium is the Lower Cretaceous Dakota Sandstone in the area east of John Martin Reservoir for south Texas roll-type sandstone deposits. Carbonaceous trash and sulfides are abundant in the Dakota Sandstone. The unit underlies a thick Upper Cretaceous section

A. M. Maarouf; V. C. Johnson

1982-01-01

376

Oil yield and uranium content of black shales  

Microsoft Academic Search

Some black shales contain as much as one hundred times more uranium than other common sedimentary rocks and they also contain organic matter that will yield oil when subjected to destructive distillation. Such shales may be referred to as uraniferous oil shales and have been considered as a potential source of both oil and uranium; oil yield and uranium determinations

1960-01-01

377

Uranium Mill Tailings Remedial Action Project surface project management plan  

SciTech Connect

This Project Management Plan describes the planning, systems, and organization that shall be used to manage the Uranium Mill Tailings Remedial Action Project (UMTRA). US DOE is authorized to stabilize and control surface tailings and ground water contamination at 24 inactive uranium processing sites and associated vicinity properties containing uranium mill tailings and related residual radioactive materials.

Not Available

1994-09-01

378

Tributyl-phosphate-impregnated sorbents for plutonium-uranium separations  

SciTech Connect

Bayer AG Lewatit OC-1023, a macroporous sorbent impregnated with tributyl phosphate (TBP), was evaluated for the separation of uranium and plutonium from mixed actinide residues. The sorbent was tested for uranium breakthrough capacity, plutonium washing, and uranium elution behavior. TBP-impregnated Amberlite XAD-4 was compared to the Lewatit OC-1023.

Alford, C.E.; Navratil, J.D.

1986-03-24

379

Maintaining the uranium resources data system and assessing the 1991 US uranium potential resources. Final report  

SciTech Connect

The Energy Information Administration`s (EIA) Uranium Resource Assessment Data (URAD) System contains information on potential resources (undiscovered) of uranium in the United States. The purpose of this report is: (1) to describe the work carried out to maintain and update the URAD system; (2)to assess the 1991 U.S. uranium potential resources in various cost categories; and (3) to describe the progress that has been made to automate the generation of the assessment reports and their subsequent transmittal by diskette.

McCammon, R.B. [Geological Survey, Reston, VA (United States); Finch, W.I.; Grundy, W.D.; Pierson, C.T. [Geological Survey, Denver, CO (United States)

1992-12-31

380

The Nopal 1 Uranium Deposit: an Overview  

NASA Astrophysics Data System (ADS)

The Nopal 1 natural analogue is located in the Pena Blanca uranium district, about 50 kms north of Chihuahua City, Mexico. The deposit is hosted in tertiary ignimbritic ash-flow tuffs, dated at 44 Ma (Nopal and Colorados formations), and overlying the Pozos conglomerate formation and a sequence of Cretaceous carbonate rocks. The deposit is exposed at the ground surface and consists of a near vertical zone extending over about 100 m with a diameter of 40 m. An interesting characteristic is that the primary mineralization has been exposed above the water table, as a result of the uplift of the Sierra Pena Blanca, and subsequently oxidized with a remobilization of hexavalent uranium. The primary mineralization has been explained by various genetic models. It is associated to an extensive hydrothermal alteration of the volcanic tuffs, locally associated to pyrite and preserved by an intense silicification. Several kaolinite parageneses occur in fissure fillings and feldspar pseudomorphs, within the mineralized breccia pipe and the barren surrounding rhyolitic tuffs. Smectites are mainly developed in the underlying weakly welded tuffs. Several radiation-induced defect centers have been found in these kaolinites providing a unique picture of the dynamics of uranium mobilization (see Allard et al., this session). Another evidence of this mobilization is given by the spectroscopy of uranium-bearing opals, which show characteristic fluorescence spectra of uranyl groups sorbed at the surface of silica. By comparison with the other uranium deposits of the Sierra Pena Blanca and the nearby Sierra de Gomez, the Nopal 1 deposit is original, as it is one of the few deposits hving retained a reduced uranium mineralization.

Calas, G.; Allard, T.; Galoisy, L.

2007-05-01

381

U. S. forms uranium enrichment corporation  

SciTech Connect

After almost 40 years of operation, the federal government is withdrawing from the uranium enrichment business. On July 1, the Department of Energy turned over to a new government-owned entity--the US Enrichment Corp. (USEC)--both the DOE enrichment plants at Paducah, Ky., and Portsmouth, Ohio, and domestic and international marketing of enriched uranium from them. Pushed by the inability of DOE's enrichment operations to meet foreign competition, Congress established USEC under the National Energy Policy Act of 1992, envisioning the new corporation as the first step to full privatization. With gross revenues of $1.5 billion in fiscal 1992, USEC would rank 275th on the Fortune 500 list of top US companies. USEC will lease from DOE the Paducah and Portsmouth facilities, built in the early 1950s, which use the gaseous diffusion process for uranium enrichment. USEC's stock is held by the US Treasury, to which it will pay annual dividends. Martin Marietta Energy Systems, which has operated Paducah since 1984 and Portsmouth since 1986 for DOE, will continue to operate both plants for USEC. Closing one of the two facilities will be studied, especially in light of a 40% world surplus of capacity over demand. USEC also will consider other nuclear-fuel-related ventures. USEC will produce only low-enriched uranium, not weapons-grade material. Indeed, USEC will implement a contract now being completed under which the US will purchase weapons-grade uranium from dismantled Russian nuclear weapons and convert it into low-enriched uranium for power reactor fuel.

Seltzer, R.

1993-07-12

382

National Uranium Resource Evaluation: Craig Quadrangle, Colorado  

SciTech Connect

The Craig Quadrangle in northwestern Colorado contains five areas that are considered favorable for uranium deposits that could contain at least 100 tons U/sub 3/O/sub 8/ at an average grade not less than 100 ppM U/sub 3/O/sub 8/ and less than 1500 m deep. Three of the areas (A, B, and C) are in the Browns Park Formation (Miocene) in the west-central part of the quadrangle and are classed as favorable for nonchannel-controlled and channel-controlled peneconcordant sandstone-type deposits (Subclasses 244 and 243). Area A also contains fault-controlled vein deposits in sandstone (Class 730). Area A contains most of the Maybell-Lay uranium mining district. Area B differs from Area A mainly in that large uranium deposits have not been discovered and developed. The Browns Park of Area C is poorly exposed and contains only a few uranium occurrences. The area is considered favorable mainly on the likely projection of the same geologic characteristics that are favorable in Area A. Area D is in the Salt Wash Member of the Morrison Formation (Upper Jurassic) in the southwest part of the Craig Quadrangle and uranium deposits are classed as nonchannel-controlled peneconcordant sandstone-type deposits (Subclass 244). The favorable Area is essentially a projection of the Meeker mining district based on the regional stratigraphy of the Salt Wash Member, and the presence of relatively thick, high-energy sandstone beds containing carbonaceous trash. Area E is in the Troublesome Formation (Miocene) in the southeastern part of the Craig Quadrangle and most uranium deposits are classed as channel-controlled peneconcordant sandstone-type deposits (Subclass 243).

Craig, L.C.; Hail, W.J. Jr.; Luft, S.J.; Boudette, E.L.; Snyder, G.L.

1982-09-01

383

Uranium in NIMROC standard igneous rock samples  

NASA Technical Reports Server (NTRS)

Results are reported for analysis of the uranium in multiple samples of each of six igneous-rock standards (dunite, granite, lujavrite, norite, pyroxenite, and syenite) prepared as geochemical reference standards for elemental and isotopic compositions. Powdered rock samples were examined by measuring delayed neutron emission after irradiation with a flux of the order of 10 to the 13th power neutrons/sq cm per sec in a nuclear reactor. The measurements are shown to compare quite favorably with previous uranium determinations for other standard rock samples.

Rowe, M. W.; Herndon, J. M.

1976-01-01

384

Determining uranium speciation in contaminated soils by molecular spectroscopic methods: Examples from the Uranium in Soils Integrated Demonstration.  

National Technical Information Service (NTIS)

The US Department of Energy's former uranium production facility located at Fernald, OH (18 mi NW of Cincinnati) is the host site for an Integrated Demonstration for remediation of uranium-contaminated soils. A wide variety of source terms for uranium con...

P. G. Allen, J. M. Berg, C. J. Chisholm-Brause, S. D. Conradson, R. J. Donohoe

1994-01-01

385

Alpha Radiolysis of Sorbed Water on Uranium Oxides and Uranium Oxyfluorides  

SciTech Connect

The radiolysis of sorbed water and other impurities contained in actinide oxides has been the focus of a number of studies related to the establishment of criteria for the safe storage and transport of these materials. Gamma radiolysis studies have previously been performed on uranium oxides and oxyfluorides (UO{sub 3}, U{sub 3}O{sub 8}, and UO{sub 2}F{sub 2}) to evaluate the long-term storage characteristics of {sup 233}U. This report describes a similar study for alpha radiolysis. Uranium oxides and oxyfluorides (with {sup 238}U as the surrogate for {sup 233}U) were subjected to relatively high alpha radiation doses (235 to 634 MGy) by doping with {sup 244}Cm. The typical irradiation time for these samples was about 1.5 years, which would be equivalent to more than 50 years irradiation by a {sup 233}U sample. Both dry and wet (up to 10 wt % water) samples were examined in an effort to identify the gas pressure and composition changes that occurred as a result of radiolysis. This study shows that several competing reactions occur during radiolysis, with the net effect that only very low pressures of hydrogen, nitrogen, and carbon dioxide are generated from the water, nitrate, and carbon impurities, respectively, associated with the oxides. In the absence of nitrate impurities, no pressures greater than 1000 torr are generated. Usually, however, the oxygen in the air atmosphere over the oxides is consumed with the corresponding oxidation of the uranium oxide. In the presence of up to 10 wt % water, the oxides first show a small pressure rise followed by a net decrease due to the oxygen consumption and the attainment of a steady-state pressure where the rate of generation of gaseous components is balanced by their recombination and/or consumption in the oxide phase. These results clearly demonstrate that alpha radiolysis of either wet or dry {sup 233}U oxides will not produce deleterious pressures or gaseous components that could compromise the long-term storage of these materials.

Icenhour, A.S.

2003-09-10

386

South Australia, Uranium Enrichment. Second Interim Report of the Uranium Enrichment Committee, February 1976.  

National Technical Information Service (NTIS)

The Report sets out the salient data relating to the establishment of a uranium processing centre at Redcliff in South Australia. It is conceived as a major development project for the Commonwealth, the South Australian Government and Australian Industry ...

1976-01-01

387

Conversion and Blending Facility highly enriched uranium to low enriched uranium as metal. Revision 1  

SciTech Connect

The mission of this Conversion and Blending Facility (CBF) will be to blend surplus HEU metal and alloy with depleted uranium metal to produce an LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. The blended LEU will be produced as a waste suitable for storage or disposal.

NONE

1995-07-05

388

Migration of uranium process wastes from the uranium-233thorium232 cycle  

Microsoft Academic Search

With the advent of fuel loadings of ²³³U in the Shippingport Reactor, it has become important to understand the migratory behavior of uranium. The purpose of this study is the determination of the parameters influencing the migration of U(VI), the most likely chemical form of uranium to be mobilized from a repository. Samples of rhyolite tuff were used to measure

S. Fried; C. Sabau; J. Hines; A. Friedman

1978-01-01

389

Fungi outcompete bacteria under increased uranium concentration in culture media.  

PubMed

As a key part of water management at the Ranger Uranium Mine (Northern Territory, Australia), stockpile (ore and waste) runoff water was applied to natural woodland on the mine lease in accordance with regulatory requirements. Consequently, the soil in these Land Application Areas (LAAs) presents a range of uranium concentrations. Soil samples were collected from LAAs with different concentrations of uranium and extracts were plated onto LB media containing no (0 ppm), low (3 ppm), medium (250 ppm), high (600 ppm) and very high (1500 ppm) uranium concentrations. These concentrations were similar to the range of measured uranium concentrations in the LAAs soils. Bacteria grew on all plates except for the very high uranium concentrations, where only fungi were recovered. Identifications based on bacterial 16S rRNA sequence analysis showed that the dominant cultivable bacteria belonged to the genus Bacillus. Members of the genera Paenibacillus, Lysinibacillus, Klebsiella, Microbacterium and Chryseobacterium were also isolated from the LAAs soil samples. Fungi were identified by sequence analysis of the intergenic spacer region, and members of the genera Aspergillus, Cryptococcus, Penicillium and Curvularia were dominant on plates with very high uranium concentrations. Members of the Paecilomyces and Alternaria were also present but in lower numbers. These findings indicate that fungi can tolerate very high concentrations of uranium and are more resistant than bacteria. Bacteria and fungi isolated at the Ranger LAAs from soils with high concentrations of uranium may have uranium binding capability and hence the potential for uranium bioremediation. PMID:23416228

Mumtaz, Saqib; Streten-Joyce, Claire; Parry, David L; McGuinness, Keith A; Lu, Ping; Gibb, Karen S

2013-06-01

390

Laboratory simulation studies of uranium mobility in natural waters  

NASA Astrophysics Data System (ADS)

The effects of imposed variations of pH and Eh on aqueous uranium mobility at 25C have been studied in three simulations of natural water systems. Constituents tested for their effect on uranium mobility were: (a) hydrous ferric oxide, to represent adsorptive solids which precipitate or dissolve in response to variations in pH and Eh. (b) kaolinite, representing minerals which, although modified by pH and Eh changes, are present as solids over the pH-Eh range of natural waters. (c) carbonate, to represent a strong uranium-complexing species. Uranium mobility measurements from each simulation were regressed against pH and Eh within a range appropriate to natural waters. Hydrous ferric oxide and kaolinite each affected uranium mobility, but in separate pH-Eh domains. Aqueous carbonate increased mobility of uranium, and adsorption of UO 2(CO 3) 34- caused colloidal dispersion of hydrous ferric oxide, possibly explaining the presence of 'hydrothermal hematite' in some uranium deposits. Enhanced uranium mobility observed in the pH-Eh domains of thermodynamically insoluble uranium oxides could be explained if the oxides were present as colloids. Uranium persisting as a mobile species, even after reduction, has implications for the near surface genesis of uranium ores.

Giblin, A. M.; Batts, B. D.; Swaine, D. J.

1981-05-01

391

Calcium Uranium Titanate - a New Pyrochlore.  

National Technical Information Service (NTIS)

A calcium uranium dititanate pyrochlore (A/sub 2/B/sub 2/O/sub 7/), as a component of a high level nuclear waste ceramic, was characterized by powder X-ray diffraction, analytical electron microscopy and selected area electron diffraction. The cubic unit ...

F. J. Dickson K. D. Hawkins T. J. White

1988-01-01

392

Experimental Leaching of Uranium from Tuffaceous Rocks.  

National Technical Information Service (NTIS)

The premise to be tested in this work is that felsic volcanic rocks particularly ash-flow tuffs, can serve as source rocks for certain uranium deposits. The applicability of this idea to several geologic environments is investigated. A genetic model is de...

P. C. Goodell R. C. Trentham

1980-01-01

393

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

Uranium contamination of the subsurface remains a persistent problem plaguing remedial design at sites across the U.S. that were involved with production, handling, storage, milling, and reprocessing of uranium for both civilian and defense related purposes. Remediation efforts to date have relied upon excavation, pump-and-treat, or passive remediation barriers (PRB?s) to remove or attenuate uranium mobility. Documented cases convincingly demonstrate that excavation and pump-and-treat methods are ineffective for a number of highly contaminated sites. There is growing concern that use of conventional PRB's, such as zero-valent iron, may be a temporary solution to a problem that will persist for thousands of years. Alternatives to the standard treatment methods are therefore warranted. The core objective of our research is to demonstrate that a phosphorous amendment strategy will result in a reduction of dissolved uranium to below the proposed drinking water standard. Our hypothesis is that long-chain sodium polyphosphate compounds forestall precipitation of sparingly soluble uranyl phosphate compounds, which is paramount to preventing fouling of wells at the point of injection.

Icenhower, Jonathan P.; Burns, Peter C.

2005-06-01

394

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

Uranium contamination of the subsurface remains a persistent problem plaguing remedial design at sites across the U.S. that were involved with production, handling, storage, milling, and reprocessing of uranium for both civilian and defense related purposes. Remediation efforts to date have relied upon excavation, pump-and-treat, or passive remediation barriers (PRB?s) to remove or attenuate uranium mobility. Documented cases convincingly demonstrate that excavation and pump-and-treat methods are ineffective for a number of highly contaminated sites. There is growing concern that use of conventional PRB?s, such as zero-valent iron, may be a temporary solution to a problem that will persist for thousands of years. Alternatives to the standard treatment methods are therefore warranted. The core objective of our research is to demonstrate that a phosphorus amendment strategy will result in a reduction of dissolved uranium to below the proposed drinking water standard. Our hypothesis is that long-chain sodium polyphosphate compounds forestall precipitation of sparingly soluble uranyl phosphate compounds, which is paramount to preventing fouling of wells at the point of injection.

Burns, Peter C.

2004-12-01

395

Production of uranium ore in capitalist countries  

Microsoft Academic Search

The uranium deposits of the USA are concentrated in the sedimentary rocks of the Colorado plateau [2, 12]. The ore bodies are adapted to arkosic sandstones, conglomerates, limestones, and argillites. The reserves are distributed into a rather small number of large deposits and a large number of small deposits. Large deposits, each with reserves of from 50 to 100 thousand

N. I. Chesnokov; V. G. Ivanov

1973-01-01

396

Sono-chemical leaching of uranium  

Microsoft Academic Search

A fundamental study on the mechanism of uranium leaching in nitric acid and sulphuric acid media has been carried out to understand the effect of the ultrasound on leaching. The use of ultrasound clearly improves the leaching rate within the studied leach acid media. The enhancement in the leaching rate in the presence of ultrasound is higher with low leach

Balasubrahmanyam Avvaru; S. B. Roy; Yogesh Ladola; Sujit Chowdhury; K. N. Hareendran; Aniruddha B. Pandit

2008-01-01

397

MEETING REPORTS: SRP Scientific Meeting: Depleted Uranium  

Microsoft Academic Search

London, January 2002 The meeting was organised by the SRP to review current research and discuss the use, dispersion into the environment and radiological impact of depleted uranium (DU) by the UK and US in recent military conflicts. Brian Spratt chaired the morning session of the meeting and stressed the need to gauge the actual risks involved in using DU

David Kestell

2002-01-01

398

National Uranium Resource Evaluation: Marfa Quadrangle, Texas  

SciTech Connect

The uranium favorability of the Marfa 1/sup 0/ by 2/sup 0/ Quadrangle, Texas, was evaluated in accordance with criteria established for the National Uranium Resource Evaluation. Surface and subsurface studies, to a 1500 m (5000 ft) depth, and chemical, petrologic, hydrogeochemical, and airborne radiometric data were employed. The entire quadrangle is in the Basin and Range Province and is characterized by Tertiary silicic volcanic rocks overlying mainly Cretaceous carbonate rocks and sandstones. Strand-plain sandstones of the Upper Cretaceous San Carlos Formation and El Picacho Formation possess many favorable characteristics and are tentatively judged as favorable for sandstone-type deposits. The Tertiary Buckshot Ignimbrite contains uranium mineralization at the Mammoth Mine. This deposit may be an example of the hydroauthigenic class; alternatively, it may have formed by reduction of uranium-bearing ground water produced during diagenesis of tuffaceous sediments of the Vieja Group. Although the presence of the deposit indicates favorability, the uncertainty in the process that formed the mineralization makes delineation of a favorable environment or area difficult. The Allen intrusions are favorable for authigenic deposits. Basin fill in several bolsons possesses characteristics that suggest favorability but which are classified as unevaluated because of insufficient data. All Precambrian, Paleozoic, other Mesozoic, and other Cenozoic environments are unfavorable.

Henry, C D; Duex, T W; Wilbert, W P

1982-09-01

399

Decarburization of uranium via electron beam processing  

Microsoft Academic Search

For many commercial and military applications, the successive Vacuum Induction Melting of uranium metal in graphite crucibles results in a product which is out of specification in carbon. The current recovery method involves dissolution of the metal in acid and chemical purification. This is both expensive and generates mixed waste. A study was undertaken at Lawrence Livermore National Laboratory to

McKoon

1998-01-01

400

Dissolution Treatment of Depleted Uranium Waste  

Microsoft Academic Search

Researchers at LLNL have developed a 3-stage process that converts pyrophoric depleted uranium metal turnings to a solidified final product that can be transported to and buried at a permitted land disposal site. The three process stages are: (1) pretreatment; (2) dissolution; and (3) solidification. Each stage was developed following extensive experimentation. This report presents the results of their experimental

D D Gates-Anderson; C A Laue; T E Fitch

2004-01-01

401

Dissolution Treatment of Depleted Uranium Waste  

SciTech Connect

Researchers at LLNL have developed a 3-stage process that converts pyrophoric depleted uranium metal turnings to a solidified final product that can be transported to and buried at a permitted land disposal site. The three process stages are: (1) pretreatment; (2) dissolution; and (3) solidification. Each stage was developed following extensive experimentation. This report presents the results of their experimental studies.

Gates-Anderson, D D; Laue, C A; Fitch, T E

2004-02-09

402

DISSOLUTION OF URANIUM METAL AND ITS ALLOYS  

Microsoft Academic Search

The most useful methods for the dissolution of uranium metal and its ; alloys are reviewed, with particular emphasis on the preparation of solutions for ; analysis. The behavior of the metal and its alloys in the common acids, ethyl ; acetate solutions of bromine and hydrogen chloride, and sodium hydroxide- ; peroxide mixtures is described. Recommendations for dissolving each

R. P. Larsen

1959-01-01

403

High Temperature Thermodynamics of Uranium Carbides.  

National Technical Information Service (NTIS)

Two articles are presented. In the first equations are proposed with four parameters for describing the activities of uranium and carbon as functions of the composition of the cubic solid solution UC(y). Formally, these equations correspond to a nonideal ...

S. S. Nikolskii I. N. Levina

1970-01-01

404

Transportable calorimeter measurements of highly enriched uranium  

Microsoft Academic Search

A sensitive calorimeter has been combined with a small temperature-controlled water bath to compose a transportable system that is capable of measuring multikilogram quantities of highly enriched uranium (HEU). The sample chamber size, 5 in. in diameter by 10 in. high, is large enough to hold sufficient HEU metal or high-grade scrap to provide a measurable thermal signal. Calorimetric measurements

C. Rudy; D. S. Bracken; P. Staples; L. Carrillo

1997-01-01

405

Uranium, the World's Largest Energy Reserve.  

National Technical Information Service (NTIS)

Uranium is the only primary energy carrier which is able to substitute for the limited fossil energy sources in the long term and to give a vital contribution to their lengthening in the intermediate term. This is pointed out in this short survey. It deal...

B. F. Roth

1982-01-01

406

Experimental Study of Uranium Plastic Scintillator Calorimeters,  

National Technical Information Service (NTIS)

As preparation for the ZEUS high resolution calorimeter, sampling calorimeters made from 3.2 mm plates of depleted uranium read out by plastic scintillator of 3 mm and 5 mm thickness have been built. The response of hadrons, electrons and muons has been m...

G. d'Agostini A. Bamberger F. Barreiro E. Bernardi K. Dierks

1988-01-01

407

Structure and phase transformations in uranium metal  

SciTech Connect

In common with other elemental actinides, metallic uranium exists in several allotropic forms, differing from one another by complex but subtle atomic rearrangements. This article reviews progress in understanding the successive phase transformations from the perspective of soft-mode instabilities.

Axe, J.D. [Brookhaven National Lab., Upton, NY (United States); Gruebel, G. [European Synchrotron Radiation Facility, 38 - Grenoble (France); Lander, G.H. [Inst., for Transurmanium Elements, Karlsruhe, (Germany)

1993-12-01

408

Plutonium to Uranium Fission Ratio Measurements.  

National Technical Information Service (NTIS)

The measurement of the ratio of plutonium to uranium fissions has for some years been used as a method of characterizing the thermal spectrum in reactor lattices. This report describes the method of analysis of this type of measurement which has been deve...

R. H. Waterson

1971-01-01

409

Removal of molybdenum from uranium solutions  

SciTech Connect

Molybdenum is removed from a uranium bearing alkaline carbonate leach solution, by adding a compound which provides lead ion to react with the molybdenum present to form insoluble lead molybdate (PbMoO/sub 4/) which precipitates from the solution.

Gardner, H.E.

1982-12-28

410

Uranium miner lung cancer study. Final report  

SciTech Connect

This study on uranium miners was started in 1957 and extended through June 30, 1986. It consisted of the routine screening of sputum from uranium miners of the Colorado Plateau, and collection of surgical and autopsy material from uranium miners who developed lung cancer. The projects resulted in: (1) Proof, for the first time, that cancer takes from 10 to 15 years to develop from the maximum accumulated carcinogenic insult and can be demonstrated through progressive cellular changes of the bronchial tree; (2) Development of a method for preserving, concentrating, and processing sputum samples. This is known as the Saccomanno Technique, and is used worldwide in diagnosing lung cancer; (3) Publication of the 1st and 2nd editions of a full-color textbook entitled ''Diagnostic Pulmonary Cytology;'' (4) Presentation of conclusive data on the effects of cigarette smoking and alpha progeny radiation on uranium miners, and information on safe radiation exposure levels; (5) Development of a brush-wash tube for collecting, concentrating, and preparing bronchial brushings and washings; (6) Development of cytological criteria which has improved sensitivity from 30% to about 60%; (7) Development of criteria for cytologic identification of carcinoma in situ, making it possible to diagnose lung cancer before it can be detected on chest x-ray.

Saccomanno, G.

1986-06-01

411

Mountain wetlands: Efficient uranium filters potential impacts  

Microsoft Academic Search

Wetlands are common in montane and subalpine settings in the Rocky Mountains, Sierra Nevada, and other mountainous regions of the western U.S. Because they are efficient filters, many contain anomalous concentrations of uranium and other metals. Sorption by organic matter, complexing of the uranyl ion, (UO2) 2+, with humic and fulvic acids, and action by bacteria has produced geochemical enrichment

Douglass E. Owen; James K. Otton

1995-01-01

412

Uranium solution mining cost model. Final report  

Microsoft Academic Search

The model represents a process oriented approach to estimating both requirements and costs associated with a commercial uranium in situ leaching project. The analysis covers the project's life cycle, from the exploration stage through project termination. The methodology computes both capital and operating requirements for an in situ project using the ''borehole mining technique.'' All costs are subsequently aggregated in

G. W. Toth; C. K. Chase

1978-01-01

413

Uranium on the Checkerboard: Crisis at Crownpoint  

ERIC Educational Resources Information Center

Some 22 companies are currently exploring for uranium in the Crownpoint, New Mexico area. Due to complicated patterns of land and mineral ownership on the Navajo Reservation, the mining companies do not feel obligated to communicate, and the Navajo are, consequently, worried about their social and physical environment. (JC)

Barry, Tom; Wood, Beth

1978-01-01

414

Thermophysical properties of gas phase uranium tetrafluoride  

NASA Technical Reports Server (NTRS)

Thermophysical data of gaseous uranium tetrafluoride (UF4) are theoretically obtained by taking into account dissociation of molecules at high temperatures (2000-6000 K). Determined quantities include specific heat, optical opacity, diffusion coefficient, viscosity, and thermal conductivity. A computer program is developed for the calculation.

Watanabe, Yoichi; Anghaie, Samim

1993-01-01

415

ACID LEACHING OF URANIUM AND THORIUM CARBIDES  

Microsoft Academic Search

Experiments with the formation of organic compounds in reaction of 6N ; HNO with uranium carbides are described. After removal of U with TBP in ; benzene, the aqueous raffinate was evaporated and the residue esterified with ; diazomethane. The presence of mellitic and oxalic acids is attributed to ; formation of graphitic carbon which is then oxidized. Up to

P. L. Pauson; J. McLean; W. J. Clelland

1963-01-01

416

ACID LEACHING OF ALUMINA FOR URANIUM RECOVERY  

Microsoft Academic Search

It was found that up to 99.9% uranium can be removed from alumina ; efficiently and economically in geometrically safe equipment by continuous ; leaching with dilute nitric acid for about eight hours. Resulting solutions of ; uranyl nitrate require littie adjustment for solvent extraction recovery ; operations. The small amount of fines present can be readily removed by settling.

W. S. Fleshman; J. R. Davis

1961-01-01

417

Heap Leaching Studies on Uranium Ore.  

National Technical Information Service (NTIS)

Laboratory amenability studies as well as a pilot heap-leaching investigation of low-grade sandstone uranium ores from Wyoming, New Mexico, and Colorado are described. Sulfuric acid heap leaching with oxidation, for 120 days, extracted up to 98 percent, 9...

C. N. Wentz H. D. Peterson R. C. Merritt

1976-01-01

418

Acid Leaching of Uranium and Thorium Carbides  

Microsoft Academic Search

IN a recent communication by Sasaki et al.1 attention is directed to the use of the carbides of uranium, plutonium and thorium as nuclear fuels and to the problems associated with processing and recovery of the irradiated fuel. It is revealed that in the acid leaching of thorium carbide (ThC2) with nitric acid of concentrations below 4 N gaseous hydrocarbons

P. L. Pauson; J. McLean; W. J. Clelland

1963-01-01

419

All-metal uranium bed loading system  

Microsoft Academic Search

The uranium bed processing system is essentially a vacuum system designed to transfer tritium gas from a large shipping container into small, portable containers called beds. The portable beds, designed to contain specific amounts of tritium or deuterium gas, are attached to various production systems for the purpose of hydriding occluder films in the production of neutron generators. The beds

Eichman

1979-01-01

420

Uranium contamination of the Aral Sea  

Microsoft Academic Search

Located in an endorrheic basin, the Aral Sea is mainly fed by water from two large rivers, the Syrdarya and the Amudarya. As a result, contaminants in dissolved and suspended form discharged by the rivers are accumulating in the lake. The northern Small Aral water contained 37g l?1uranium and water in the western basin of the Large Aral up to

Jana Friedrich

2009-01-01

421

Aqueous uranium concentrations in the natural environment.  

National Technical Information Service (NTIS)

Published geochemical data from groundwater and surface water throughout the world has been compiled in order to compare the concentration of naturally occurring dissolved uranium to lithology, sampling depth, pH, Eh, HCO(sub 3), SO(sub 4) and PO(sub 4) c...

M. T. Anderson

1992-01-01

422

Method for the Separation of Uranium Isotopes.  

National Technical Information Service (NTIS)

A method for the separation of uranium isotopes, particularly U235 is disclosed. The method employs a frequency selective laser irradiation of an adiabatically cooled beam of UF6 molecules, followed by the 'chemionization' i.e., SbF5 + UF6 SbF6(-) + UF5(+...

A. Auerbach

1980-01-01

423

URANIUM MINING TENORM TECHNICAL REPORT - VOLUME I  

EPA Science Inventory

The intent of this effort is to publish a series of individual reports, using a consistent approach, on industries that makes use of or produces TENORM waste. The first three products of this effort will be a URANIUM MINE LOCATION DATABASE, included in the Science Inventory as a...

424

Statistical design of a uranium corrosion experiment  

SciTech Connect

This work supports an experiment being conducted by Roland Schulze and Mary Ann Hill to study hydride formation, one of the most important forms of corrosion observed in uranium and uranium alloys. The study goals and objectives are described in Schulze and Hill (2008), and the work described here focuses on development of a statistical experiment plan being used for the study. The results of this study will contribute to the development of a uranium hydriding model for use in lifetime prediction models. A parametric study of the effect of hydrogen pressure, gap size and abrasion on hydride initiation and growth is being planned where results can be analyzed statistically to determine individual effects as well as multi-variable interactions. Input to ESC from this experiment will include expected hydride nucleation, size, distribution, and volume on various uranium surface situations (geometry) as a function of age. This study will also address the effect of hydrogen threshold pressure on corrosion nucleation and the effect of oxide abrasion/breach on hydriding processes. Statistical experiment plans provide for efficient collection of data that aids in understanding the impact of specific experiment factors on initiation and growth of corrosion. The experiment planning methods used here also allow for robust data collection accommodating other sources of variation such as the density of inclusions, assumed to vary linearly along the cast rods from which samples are obtained.

Wendelberger, Joanne R [Los Alamos National Laboratory; Moore, Leslie M [Los Alamos National Laboratory

2009-01-01

425

DIFFUSION OF XENON IN URANIUM MONOCARBIDE (thesis)  

Microsoft Academic Search

The lattice diffusion coefficient of Xe¹³³ in cast uranium ; monocarbide was measured in postirradiation anneal experiments in the temperature ; range 100 to 2000 un. Concent 85% C. It was found that the diffusion coefficient ; of specimens consisting of large grains (700 to 1000 ) was best approximated ; by D = (1.17 450 deg C in a

Shaked

1962-01-01

426

Thermodynamic Properties of Uranium--Mercury System.  

National Technical Information Service (NTIS)

The EMF values in the fused salt cells of the type U( alpha )/KCl--LiCl--BaCl sub 2 eutectic, UCl sub 3 /U--Hg alloy, for the different two-phase alloys in the uranium--mercury system have been measured and the thermodynamic properties of this system have...

T. S. Lee

1979-01-01

427

Linear solution for hydriding of uranium.  

National Technical Information Service (NTIS)

A set of equations describing the hydriding of solid pieces of uranium is presented, together with an approximate solution of the equations. The solution predicts a constant velocity of the spall front in the solid piece, which leads to a constant value o...

J. R. Kirkpatrick J. B. Condon

1990-01-01

428

Bernabe Montano uranium deposit, Sandoval County  

SciTech Connect

Uranium mineralization was discovered on the Bernabe Montano Grant early in 1971. This old land grant, which is part of the Laguna Indian Reservation, is approximately 25 mile northwest of Albuquerque, New Mexico. About 2,000 holes have been drilled on this property to date, and an ore reserve of 10 to 20 million lbs of uranium oxide has been delineated in the Westwater Canyon Member of the Morrison Formation. The mineralization consists of multiple, stacked blankets of mineralized humate which appear to be localized in an area of slightly thicker and more laterally continuous sandstones. The blankets occur along a relatively straight mineral trend about a half mile wide and several miles in length. Holes drilled on-trend usually encounter gamma anomalies, whereas holes drilled off-trend are barren. The uranium is believed to have been carried through the Westwater Canyon Member by ground water that followed the palochannel systems shortly after burial in Late Jurassic time. This discovery once again confirms the trend-ore concept, and it probably represents the present eastern economic limit of the Grants mineral belt. The orebody is unusual because it occurs in a structurally deformed area called the Rio Puerco fault zone. The mineralization, which does not conform to a roll-front model, represents an important addition to the ore reserves of the Grants uranium region.

Kozusko, R.G. (Conoco Minerals Co., Spokane, WA); Saucier, A.E.

1980-01-01

429

DEVELOPMENT OF TECHNIQUES FOR ROLLING URANIUM METAL  

Microsoft Academic Search

Uranium can be rolled from cast metal or forged ingot to sheet ; satisfactory for cupping, deep drawing,and similar fabrication procedures by a ; combination of hot breakdown in the neighborhood of 600 deg C and warm finishing ; at 225 to 325 deg C. Sheet may also be obtained by hot rolling alone and by warm ; rolling alone.

D. E. Deutsch; G. S. Hanks; J. M. Taub; D. T. Doll; G. E. Jaynes; R. E. Anderson; V. Vigil; R. Osborn; G. Sweeney

1950-01-01

430

Directionally Solidified Uranium--Silicon Hypoeutectic Composite.  

National Technical Information Service (NTIS)

When uranium--0.763 wt percent silicon (hypoeutectic) is directionally solidified, an in-situ composite is formed. This composite must be heat treated to decompose the U sub 3 Si sub 2 (formed during solidification) to U sub 3 Si in order to achieve the i...

R. C. Anderson

1975-01-01

431

Radiological hazards of uranium mill tailings piles  

Microsoft Academic Search

This paper examines reasons for the radiological health problems associated with the front end of the nuclear fuel cycle. The increases of radioactivity in the general environment attributable to uranium mill tailings are small but never ending. Sources of radiation - mainly particulate matter and radon gas - are discussed. Management of the piles seems to provide the only viable

G. A. Watford; J. A. Jr. Wethington

1981-01-01

432

Understanding Uranium Behavior in a Reduced Aquifer  

NASA Astrophysics Data System (ADS)

Uranium contamination of groundwater is a concern at several US Department of Energy sites, such Old Rifle, CO. Uranium transport in the environment is mainly controlled by its oxidation state, since oxidized U(VI) is relatively mobile, whereas U(IV) is relatively insoluble. Bio-remediation of contaminated aquifers aims at immobilizing uranium in a reduced form. Previous laboratory and field studies have shown that adding electron donor (lactate, acetate, ethanol) to groundwater stimulates the activity of metal- and sulfate-reducing bacteria, which promotes U(VI) reduction in contaminated aquifers. However, obtaining information on chemical and physical forms of U, Fe and S species for sediments biostimulated in the field, as well as kinetic parameters such as U(VI) reduction rate, is challenging due to the low concentration of uranium in the aquifers (typically < 10 ppm) and the expense of collecting large number of cores. An in-situ technique has been developed for studying uranium, iron and sulfur reduction dynamics during such bioremediation episodes. This technique uses in-well columns to obtain direct access to chemical and physical forms of U(IV) produced in the aquifer, evolving microbial communities, and trace and major ion groundwater constituents. While several studies have explored bioreduction of uranium under sulfate-reducing conditions, less attention has been paid to the initial iron-reducing phase, noted as being of particular importance to uranium removal. The aim of this work was to assess the formation of U(IV) during the early stages of a bio-remediation experiment at the Old Rifle site, CO, from early iron-reducing conditions to the transition to sulfate-reducing conditions. Several in-well chromatographic columns packed with sediment were deployed and were sampled at different days after the start of bio-reduction. X-ray absorption spectroscopy and X-ray microscopy were used to obtain information on Fe, S and U speciation and distribution. Chemical extractions of the reduced sediments have also been performed, to determine the rate of Fe(II) and U(IV) accumulation.

Janot, N.; Lezama-Pacheco, J. S.; Williams, K. H.; Bernier-Latmani, R.; Long, P. E.; Davis, J. A.; Fox, P. M.; Yang, L.; Giammar, D.; Cerrato, J. M.; Bargar, J.

2012-12-01

433

Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils  

SciTech Connect

A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group minerals react to form U(VI)- bearing aluminum phosphates. (author)

Jerden, James L. Jr. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 (United States)

2007-07-01

434

RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION  

SciTech Connect

The H Canyon online spectrophotometers are calibrated for measurement of the uranium and nitric acid concentrations of several tanks in the 2nd Uranium Cycle.[1] The spectrometers, flow cells, and prediction models are currently optimized for a process in which uranium concentrations are expected to range from 0-15 g/L and nitric acid concentrations from 0.05-6 M. However, an upcoming processing campaign will involve 'Super Kukla' material, which has a lower than usual enrichment of fissionable uranium. Total uranium concentrations will be higher, spanning approximately 0-30 g/L U, with no change in the nitric acid concentrations. The new processing conditions require the installation of new flow cells with shorter path lengths. As the process solutions have a higher uranium concentration, the shorter path length is required to decrease the absorptivity to values closer to the optimal range for the instrument. Also, new uranium and nitric acid prediction models are required to span the extended uranium concentration range. The models will be developed for the 17.5 and 15.4 tanks, for which nitric acid concentrations will not exceed 1 M. The restricted acid range compared to the original models is anticipated to reduce the measurement uncertainty for both uranium and nitric acid. The online spectrophotometers in H Canyon Second Uranium Cycle were modified to allow measurement of uranium and nitric acid for the Super Kukla processing campaign. The expected uranium concentrations, which are higher than those that have been recently processed, required new flow cells with one-third the optical path length of the existing cells. Also, new uranium and nitric acid calibrations were made. The estimated reading uncertainties (2{sigma}) for Tanks 15.4 and 17.5 are {approx}5% for uranium and {approx}25% for nitric acid.

Lascola, R

2008-10-29

435

Chemical Equilibrium of the Dissolved Uranium in Groundwaters From a Spanish Uranium-Ore Deposit  

SciTech Connect

The main objectives of this work are to determine the hydrogeochemical evolution of an uranium ore and identify the main water/rock interaction processes that control the dissolved uranium content. The Mina Fe uranium-ore deposit is the most important and biggest mine worked in Spain. Sageras area is located at the north part of the Mina Fe, over the same ore deposit. The uranium deposit was not mined in Sageras and was only perturbed by the exploration activities performed 20 years ago. The studied area is located 10 Km northeast of Ciudad Rodrigo (Salamanca) at an altitude over 650 m.a.s.l. The uranium mineralization is related to faults affecting the metasediments of the Upper Proterozoic to Lower Cambrian schist-graywacke complex (CEG), located in the Centro-Iberian Zone of the Hesperian Massif . The primary uranium minerals are uraninite and coffinite but numerous secondary uranium minerals have been formed as a result of the weathering processes: yellow gummite, autunite, meta-autunite, torbernite, saleeite, uranotile, ianthinite and uranopilite. The water flow at regional scale is controlled by the topography. Recharge takes place mainly in the surrounding mountains (Sierra Pena de Francia) and discharge at fluvial courses, mainly Agueda and Yeltes rivers, boundaries S-NW and NE of the area, respectively. Deep flows (lower than 100 m depth) should be upwards due to the river vicinity, with flow directions towards the W, NW or N. In Sageras-Mina Fe there are more than 100 boreholes drilled to investigate the mineral resources of the deposit. 35 boreholes were selected in order to analyze the chemical composition of groundwaters based on their depth and situation around the uranium ore. Groundwater samples come from 50 to 150 m depth. The waters are classified as calcium-bicarbonate type waters, with a redox potential that indicates they are slightly reduced (values vary between 50 to -350 mV). The TOC varies between <0.1 and 4.0 mgC/L and the dissolved uranium has a maximum value of 7.7 mg/L. According the analytical data of dissolved uranium, the mineral closest to equilibrium seems to be UO{sub 2}(am). The tritium contents in the groundwaters vary between 1.5 and 7.3 T.U. Considering that the mean value of tritium in rainwater from the studied area has a value of 4 T.U., it can be concluded that the residence times of the groundwaters are relatively short, not longer than 50 years in the oldest case. (authors)

Garralon, Antonio; Gomez, Paloma; Turrero, Maria Jesus; Buil, Belen; Sanchez, Lorenzo [Departamento de Medio Ambiente, CIEMAT, Avda. Complutense 22. Edificio 19, Madrid, 28040 (Spain)

2007-07-01

436

Experimental Reprocessing of Irradiated Uranium Fuel from BOR-60 Reactor by Fluoride Volatility Method.  

National Technical Information Service (NTIS)

The results are described of experiments on fluoride regeneration of irradiated assemblies of the BOR-60 reactor with uranium dioxide, with an average burn-up about 10% and a hold-up time of 3 and 6 months prior to reprocessing. In the course of the exper...

I. K. Kikoin V. A. Tsykanov M. A. Dem'yanovich

1976-01-01

437

SEPARATION OF URANIUM FROM THORIUM BY LIQUID METAL EXTRACTION THORIUM RECOVERY AND FISSION PRODUCT DISTRIBUTION  

Microsoft Academic Search

Additional results were obtained on the small-scale separation of ; uranium from thorium by molten magnesium extraction. This process is aimed at ; the separation and recovery of uranium and thorium from a thorium breeder blanket. ; On dissolution of a thorium-uranium alloy in molten magnesium, 90 to 95% of the ; uranium introduced was recovered as a uranium -thorium

J. D. Chilton; L. A. Hanson; E. W. Murbach; F. W. Dodge

1962-01-01

438

The roles of organic matter in the formation of uranium deposits in sedimentary rocks  

Microsoft Academic Search

Because reduced uranium species have a much smaller solubility than oxidized uranium species and because of the strong association of organic matter (a powerful reductant) with many uranium ores, reduction has long been considered to be the precipitation mechanism for many types of uranium deposits. Organic matter may also be involved in the alterations in and around tabular uranium deposits,

Charles S. Spirakis

1996-01-01

439

Assessing the environmental availability of uranium in soils and sediments  

SciTech Connect

Soils and sediments contaminated with uranium pose certain environmental and ecological risks. At low to moderate levels of contamination, the magnitude of these risks depends not only on the absolute concentrations of uranium in the material but also on the availability of the uranium to drinking water supplies, plants, or higher organisms. Rational approaches for regulating the clean-up of sites contaminated with uranium, therefore, should consider the value of assessing the environmental availability of uranium at the site before making decisions regarding remediation. The purpose of this work is to review existing approaches and procedures to determine their potential applicability for assessing the environmental availability of uranium in bulk soils or sediments. In addition to making the recommendations regarding methodology, the authors have tabulated data from the literature on the aqueous complexes of uranium and major uranium minerals, examined the possibility of predicting environmental availability of uranium based on thermodynamic solubility data, and compiled a representative list of analytical laboratories capable of performing environmental analyses of uranium in soils and sediments.

Amonette, J.E.; Holdren, G.R. Jr.; Krupa, K.M.; Lindenmeier, C.W. [Pacific Northwest Lab., Richland, WA (United States)

1994-06-01

440

Effectiveness of chelation therapy with time after acute uranium intoxication  

SciTech Connect

The effect of increasing the time interval between acute uranium exposure and chelation therapy was studied in male Swiss mice. Gallic acid, 4,5-dihydroxy-1,3- benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) were administered ip at 0, 0.25, 1, 4, and 24 hr after sc injection of 10 mg/kg of uranyl acetate dihydrate. Chelating agents were given at doses equal to one-fourth of their respective LD50 values. Daily elimination of uranium into urine and feces was determined for 4 days after which time the mice were killed, and the concentration of uranium was measured in kidney, spleen, and bone. The excretion of uranium was especially rapid in the first 24 hr. Treatment with Tiron or gallic acid at 0, 0.25, or 1 hr after uranium exposure significantly increased the total excretion of the metal. In kidney and bone, only administration of Tiron at 0, 0.25, or 1 hr after uranium injection, or gallic acid at 1 hr after uranium exposure significantly reduced tissue uranium concentrations. Treatment at later times (4 to 24 hr) did not increase the total excretion of the metal and did not decrease the tissue uranium concentrations 4 days after uranyl acetate administration. The results show that the length of time before initiating chelation therapy for acute uranium intoxication greatly influences the effectiveness of this therapy.

Domingo, J.L.; Ortega, A.; Llobet, J.M.; Corbella, J. (Univ. of Barcelona, Reus (Spain))

1990-01-01

441

Uranium provinces of North America; their definition, distribution, and models  

USGS Publications Warehouse

Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River?Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada. Sandstone uranium deposits are of two principal subtypes, tabular and roll-front. Tabular sandstone uranium deposits are mainly in upper Paleozoic and Mesozoic rocks in the Colorado Plateau Uranium Province (CPUP). Roll-front sandstone uranium deposits are in Tertiary rocks of the Rocky Mountain and Intermontane Basins Uranium Province (RMIBUP), and in a narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico. Volcanic uranium deposits are concentrated in the Basin and Range Uranium Province (BRUP) stretching from the McDermitt caldera at the Oregon-Nevada border through the Marysvale district of Utah and Date Creek Basin in Arizona and south into the Sierra de Pe?a Blanca District, Chihuahua, Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Lower Permian Phosphoria Formation in Idaho and adjacent States, but only in Florida has economic recovery been successful. The Florida Phosphorite Uranium Province (FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum, nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces. Many major epochs of uranium mineralization occurred in North America. In the BRELUP, uranium minerals were concentrated in placers during the Early Proterozoic (2,500?2,250 Ma). In the ABUP, the unconformity-related deposits were most likely formed initially by hot saline formational water related to diagenesis (?1,400 to 1,330 Ma) and later reconcentrated by hydrothermal events at ?1,280??1,000, ?575, and ?225 Ma. Subsequently in North America, only minor uranium mineralization occurred until after continental collision in Permian time (255 Ma). Three principal epochs of uranium mineralization occurred in the CPUP: (1) ??210?200 Ma, shortly after Late Triassic sedimentation; (2) ??155?150 Ma, in Late Jurassic time; and (3) ??135 Ma, after sedimentation of the Upper Jurassic Morrison Formation. The most likely source of the uranium was silicic volcaniclastics for the three epochs derived from a volcanic island arc at the west edge of the North American continent. Uranium mineralization occurred during Eocene, Miocene, and Pliocene times in the RMIBUP, GCUP, and BRUP. Volcanic activity took place near the west edge of the continent during and shortly after sedimentation of the host rocks in these three provinces. Some volcanic centers in the Sierra de Pe?a Blanca district within the BRUP may have provided uranium-rich ash to host rocks in the GCUP. Most of the uranium provinces in North America appear to have a common theme of close associations to volcanic activity related to the development of the western margin of the North American plate. The south and west margin of the Canadian Shield formed the leading edge of the progress of uranium source development and mineralization from the Proterozoic to the present. The development of favorable hosts and sources of uranium is related to various tectonic elements developed over time. Periods of major uranium mineralization in North America were Early Proterozoic, Middle Proterozoic, Late Triassic?Early Jurassic, Early Cretaceous, Oligocene, and Miocene. Tertiary mineralization was the most pervasive, covering most of Western and Southern North America.

Finch, Warren Irvin

1996-01-01

442

Aquifer restoration at in-situ leach uranium mines: evidence for natural restoration processes  

SciTech Connect

Pacific Northwest Laboratory conducted experiments with aquifer sediments and leaching solution (lixiviant) from an in-situ leach uranium mine. The data from these laboratory experiments and information on the normal distribution of elements associated with roll-front uranium deposits provide evidence that natural processes can enhance restoration of aquifers affected by leach mining. Our experiments show that the concentration of uranium (U) in solution can decrease at least an order of magnitude (from 50 to less than 5 ppM U) due to reactions between the lixiviant and sediment, and that a uranium solid, possibly amorphous uranium dioxide, (UO/sub 2/), can limit the concentration of uranium in a solution in contact with reduced sediment. The concentrations of As, Se, and Mo in an oxidizing lixiviant should also decrease as a result of redox and precipitation reactions between the solution and sediment. The lixiviant concentrations of major anions (chloride and sulfate) other than carbonate were not affected by short-term (less than one week) contact with the aquifer sediments. This is also true of the total dissolved solids level of the solution. Consequently, we recommend that these solution parameters be used as indicators of an excursion of leaching solution from the leach field. Our experiments have shown that natural aquifer processes can affect the solution concentration of certain constituents. This effect should be considered when guidelines for aquifer restoration are established.

Deutsch, W.J.; Serne, R.J.; Bell, N.E.; Martin, W.J.

1983-04-01

443

Utilizing Uranium-Uranium Collisions at Relativistic Energies to Recreate the Little Big Bang  

NASA Astrophysics Data System (ADS)

Based on strong interaction theories it has been predicted that collisions between two heavy nuclei at relativistic energies can create on earth the same form of matter, the Quark-Gluon Plasma (QGP), that filled the universe for the first moment of its existence after the Big Bang. Recent experiments at the European Laboratory for Particle Physics (CERN) have found compelling evidence for the formation of the QGP in lead-on-lead collisions at relativistic energies[1]. However, since in the lead-on-lead collisions the energy density reached is just slightly above the threshold for the formation of the QGP, more conclusive evidence of this state of matter is needed. It is therfore important to investigate new approaches to increase the energy density during the reaction[2]. In this work we explore the possibility to use collisions between two uranium nuclei which are not only heavier but also highly deformed. In particular, we study deformation and orientation effects on compression, collective flow and particle production within a relativistic transport model ART. We found that the energy density in uranium-on-uranium collisions increase by about 30% and lasts approximately 50% longer than the lead-on- lead collisions. New opportunities provided by the uranium-on-uranium collisions in studying properties of the QGP will be discussed. 1 New York Times, Feb. 10, 2000. 2 Bao-An Li, Physical Review C61, 021903(R) (2000).

Tilley, M.; Li, B.-A.; Sustich, A.

2000-10-01

444

Uranium contents in plants and mushrooms grown on a uranium-contaminated site near Ronneburg in Eastern Thuringia/Germany.  

PubMed

Uranium concentrations in cultivated (sunflower, sunchoke, potato) and native plants, plant compartment specimens, and mushrooms, grown on a test site within a uranium-contaminated area in Eastern Thuringia, were analyzed and compared. This test site belongs to the Friedrich-Schiller University Jena and is situated on the ground of a former but now removed uranium mine waste leaching heap. For determination of the U concentrations in the biomaterials, the saps of the samples were squeezed out by using an ultracentrifuge, after that, the uranium concentrations in the saps and the remaining residue were measured, using ICP-MS. The study further showed that uranium concentrations observed in plant compartment and mushroom fruiting bodies sap samples were always higher than their associated solid residue sample. Also, it was found that the detected uranium concentration in the root samples were always higher than were observed in their associated above ground biomass, e.g., in shoots, leaves, blossoms etc. The highest uranium concentration was measured with almost 40ppb U in a fruiting body of a mushroom and in roots of butterbur. However, the detected uranium concentrations in plants and mushrooms collected in this study were always lower than in the associated surface and soil water of the test site, indicating that under the encountered natural conditions, none of the studied plant and mushroom species turned out to be a hyperaccumulator for uranium, which could have extracted uranium in sufficient amounts out of the uranium-contaminated soil. In addition, it was found that the detected uranium concentrations in the sap samples, despite being above the sensitivity limit, proved to be too low-in combination with the presence of fluorescence quenching substances, e.g., iron and manganese ions, and/or organic quenchers-to extract a useful fluorescence signal, which could have helped to identify the uranium speciation in plants. PMID:23812734

Baumann, Nils; Arnold, Thuro; Haferburg, Gtz

2014-06-01

445

Statistical data of the uranium industry  

SciTech Connect

This document is a compilation of historical facts and figures through 1979. These statistics are based primarily on information provided voluntarily by the uranium exploration, mining, and milling companies. The production, reserves, drilling, and production capability information has been reported in a manner which avoids disclosure of proprietary information. Only the totals for the $1.5 reserves are reported. Because of increased interest in higher cost resources for long range planning purposes, a section covering the distribution of $100 per pound reserves statistics has been newly included. A table of mill recovery ranges for the January 1, 1980 reserves has also been added to this year's edition. The section on domestic uranium production capability has been deleted this year but will be included next year. The January 1, 1980 potential resource estimates are unchanged from the January 1, 1979 estimates.

none,

1980-01-01

446

Uranium series dating of Allan Hills ice  

NASA Technical Reports Server (NTRS)

Uranium-238 decay series nuclides dissolved in Antarctic ice samples were measured in areas of both high and low concentrations of volcanic glass shards. Ice from the Allan Hills site (high shard content) had high Ra-226, Th-230 and U-234 activities but similarly low U-238 activities in comparison with Antarctic ice samples without shards. The Ra-226, Th-230 and U-234 excesses were found to be proportional to the shard content, while the U-238 decay series results were consistent with the assumption that alpha decay products recoiled into the ice from the shards. Through this method of uranium series dating, it was learned that the Allen Hills Cul de Sac ice is approximately 325,000 years old.

Fireman, E. L.

1986-01-01

447

Uranium enrichment management review: summary of analysis  

SciTech Connect

In May 1980, the Assistant Secretary for Resource Applications within the Department of Energy requested that a group of experienced business executives be assembled to review the operation, financing, and management of the uranium enrichment enterprise as a basis for advising the Secretary of Energy. After extensive investigation, analysis, and discussion, the review group presented its findings and recommendations in a report on December 2, 1980. The following pages contain background material on which that final report was based. This report is arranged in chapters that parallel those of the uranium enrichment management review final report - chapters that contain summaries of the review group's discussion and analyses in six areas: management of operations and construction; long-range planning; marketing of enrichment services; financial management; research and development; and general management. Further information, in-depth analysis, and discussion of suggested alternative management practices are provided in five appendices.

Not Available

1981-01-01

448

In-line assay monitor for uranium hexafluoride  

DOEpatents

An in-line assay monitor for determining the content of uranium-235 in a uranium hexafluoride gas isotopic separation system is provided which removes the necessity of complete access to the operating parameters of the system for determining the uranium-235 content. The method and monitor for carrying out the method involve cooling of a radiation pervious chamber connected in fluid communication with the selected point in the system to withdraw a specimen and solidify the specimen in the chamber. The specimen is irradiated by means of an ionizing radiation source of energy different from that of the 185 keV gamma emissions from uranium-235. The uranium-235 content of the specimen is determined from comparison of the accumulated 185 keV energy counts and reference energy counts. The latter is used to measure the total uranium isotopic content of the specimen.

Wallace, S.A.

1980-03-21

449

Development of uranium metal targets for {sup 99}Mo production  

SciTech Connect

A substantial amount of high enriched uranium (HEU) is used for the production of medical-grade {sup 99}Mo. Promising methods of producing irradiation targets are being developed and may lead to the reduction or elimination of this HEU use. To substitute low enriched uranium (LEU) for HEU in the production of {sup 99}Mo, the target material may be changed to uranium metal foil. Methods of fabrication are being developed to simplify assembly and disassembly of the targets. Removal of the uranium foil after irradiation without dissolution of the cladding is a primary goal in order to reduce the amount of liquid radioactive waste material produced in the process. Proof-of-concept targets have been fabricated. Destructive testing indicates that acceptable contact between the uranium foil and the cladding can be achieved. Thermal annealing tests, which simulate the cladding/uranium diffusion conditions during irradiation, are underway. Plans are being made to irradiate test targets.

Wiencek, T.C.; Hofman, G.L.

1993-10-01

450

Measurements of uranium mass confined in high density plasmas  

NASA Technical Reports Server (NTRS)

An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

Stoeffler, R. C.

1976-01-01

451

National Uranium Resource Evaluation: Walker Lake Quadrangle, California and Nevada  

SciTech Connect

The Miocene Relief Peak Formation occurs in the Sierra Nevada, where it consists mainly of andesitic flows, autobrecciated flows, and mudflows. However, fluviatile rocks are common in the lower part of the formation. They contain abundant carbonaceous material, are commonly permeable, and are interbedded with less permeable rocks. The Juniper mine, the principal uranium occurrence in the fluviatile rocks, reportedly has produced more than 20 tons of U/sub 3/O/sub 8/. Although rocks of the Relief Peak Formation lack aerial radiometric uranium anomalies and generally have only average uranium content away from uranium occurrences, the fluviatile rocks of the formation are considered favorable for uranium deposits because of their lithologic characteristics and uranium occurrences. Some areas of Tertiary sedimentary rocks presently are categorized as unfavorable for the required minimum endowment. They have some geologically favorable characteristics, however, as well as indications of industry exploration activities, and they may prove to be favorable as more information becomes available.

Durham, D.L.; Felmlee, J.K.

1982-09-01

452

Reductive dissolution approaches to removal of uranium from contaminated soils  

SciTech Connect

Traditional approaches to uranium recovery from ores have employed oxidation of U(IV) minerals to form the uranyl cation which is subsequently complexed by carbonate or maintained in solution by strong acids. Reductive approaches for uranium decontamination have been limited to removing soluble uranium from solutions by formation of U{sup 4+} which readily hydrolyses and precipitates. As part of the Uranium in Soils Integrated Demonstration, we have developed a reductive approach to solubilization of uranium from contaminated soils which employs reduction to destabilize U(VI) solid and sorbed species, and strong chelators for U(IV) to prevent hydrolysis and solubilize the reduced from. This strategy has particular application to sites where the uranium is present primarily as intractable U(VI) phases and where high fractions of the contamination must be removed to meet regulatory requirements.

Brainard, J.R.; Iams, H.D.; Strietelmeier, B.A.; Del-Rio Garcia, M.

1994-06-01

453

Extraction behavior of uranium(VI) with polyurethane foam  

SciTech Connect

The extraction of uranium(VI) from aqueous solution with polyether-based polyurethane (PU) foam was studied. The effects of the kinds and concentrations of nitrate salts, uranium(VI) concentration, temperature, nitric acid concentration, pH, the content of poly(ethylene oxide) in the polyurethane foam, and the ratio of PU foam weight and solution volume on the extraction of uranium(VI) were investigated. The interferences of fluoride and carbonate ions on the extraction of uranium(VI) were also examined, and methods to overcome both interferences were suggested. It was found that no uranium was extracted in the absence of a nitrate salting-out agent, and the extraction behaviors of uranium(IV) with polyurethane foam could be explained in terms of an etherlike solvent extraction mechanism. In addition, the percentage extraction of a multiple stage was also estimated theoretically.

Tingchia Huang; Donghwang Chen (National Cheng Kung Univ., Tainan (Taiwan)); Muchang Shieh; Chingtsven Huang (Inst. of Nuclear Energy Research, Lung-Tan (Taiwan))

1992-10-01

454

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

Uranium contamination of the subsurface has remained a persistent problem plaguing remedial design at sites across the U.S. that were involved with production, handling, storage, milling, and reprocessing of fissile uranium for both civilian and defense related purposes. Remediation efforts to date have relied upon excavation, pump-and-treat, or passive remediation barriers (PRB's) to remove or attenuate uranium mobility. Documented cases convincingly demonstrate that excavation and pump-and-treat methods are ineffective for a number of highly contaminated sites. There is growing concern that use of conventional PRB?s, such as zero-valent iron, are a temporary solution to a problem that will persist for thousands of years. Alternatives to the standard treatment methods are therefore warranted. The core objective of our research is to demonstrate that a phosphorus amendment strategy will result in a reduction of dissolved uranium to below the proposed drinking water standard. Our hypothesis is that long-chain polyphosphate compounds forestall precipitation of sparingly soluble uranyl phosphate compounds, which is key to preventing fouling of wells at the point of injection. Our other fundamental objective is to synthesize and correctly characterize the uranyl phosphate phases that form in the geochemical conditions under consideration. This report summarizes work conducted at the University of Notre Dame through November of 2003 under DOE grant DE-FG07-02ER63489, which has been funded since September, 2002. The objectives at Notre Dame are development of synthesis techniques for uranyl phosphate phases, together with detailed structural and chemical characterization of the myriad of uranyl phosphate phases that may form under geochemical conditions under consideration.

Burns, Peter C.

2005-06-01

455

Texture in ZIRCALOY-clad uranium  

Microsoft Academic Search

An enriched (30%²³⁵U) uranium target is being fabricated for the ANL spallation neutron source (IPNS). They have measured the orientation distribution of neutron diffraction intensities (texture) of test casting made of depleted ²³⁸U. Their results indicate the presence of large grains which may swell anisotropically with radiation damage and produce a separation of the ZIRCALOY protective cladding from the surface

F. Ross; D. Reichel; A. Krawitz; M. Mueller; J. Richardson

2009-01-01

456

Engineering assessment of inactive uranium mill tailings  

SciTech Connect

The Grand Junction site has been reevaluated in order to revise the October 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Grand Junction, Colorado. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.9 million tons of tailings at the Grand Junction site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation are also factors. The eight alternative actions presented herein range from millsite and off-site decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Options II through VIII). Cost estimates for the eight options range from about $10,200,000 for stabilization in-place to about $39,500,000 for disposal in the DeBeque area, at a distance of about 35 mi, using transportation by rail. If transportation to DeBeque were by truck, the cost estimated to be about $41,900,000. Three principal alternatives for the reprocessing of the Grand Junction tailings were examined: (a) heap leaching; (b) treatment at an existing mill; and (c) reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be about $200/lb by heap leach and $150/lb by conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Therefore, reprocessing the tailings for uranium recovery appears not to be economically attractive.

Not Available

1981-07-01

457

The ultimate disposition of depleted uranium  

SciTech Connect

Significant amounts of the depleted uranium (DU) created by past uranium enrichment activities have been sold, disposed of commercially, or utilized by defense programs. In recent years, however, the demand for DU has become quite small compared to quantities available, and within the US Department of Energy (DOE) there is concern for any risks and/or cost liabilities that might be associated with the ever-growing inventory of this material. As a result, Martin Marietta Energy Systems, Inc. (Energy Systems), was asked to review options and to develop a comprehensive plan for inventory management and the ultimate disposition of DU accumulated at the gaseous diffusion plants (GDPs). An Energy Systems task team, under the chairmanship of T. R. Lemons, was formed in late 1989 to provide advice and guidance for this task. This report reviews options and recommends actions and objectives in the management of working inventories of partially depleted feed (PDF) materials and for the ultimate disposition of fully depleted uranium (FDU). Actions that should be considered are as follows. (1) Inspect UF{sub 6} cylinders on a semiannual basis. (2) Upgrade cylinder maintenance and storage yards. (3) Convert FDU to U{sub 3}O{sub 8} for long-term storage or disposal. This will include provisions for partial recovery of costs to offset those associated with DU inventory management and the ultimate disposal of FDU. Another recommendation is to drop the term tails'' in favor of depleted uranium'' or DU'' because the tails'' label implies that it is waste.'' 13 refs.

Not Available

1990-12-01

458

Uranium enrichment export control guide: Gaseous diffusion  

SciTech Connect

This document was prepared to serve as a guide for export control officials in their interpretation, understanding, and implementation of export laws that relate to the Zangger International Trigger List for gaseous diffusion uranium enrichment process components, equipment, and materials. Particular emphasis is focused on items that are especially designed or prepared since export controls are required for these by States that are party to the International Nuclear Nonproliferation Treaty.

Not Available

1989-09-01

459

Uranium isotopes in Tunisian bottled mineral waters  

Microsoft Academic Search

234U and 238U activity concentrations and their relative effective doses have been determined in 10 bottled mineral waters in Tunisia. Alpha spectrometry was used as technique to measure uranium isotopes. The obtained isotopic ratio 234U\\/238U varies between 1.1 and 3 which means that the two isotopes are not in radioactive equilibrium. Measured activity concentration varies between 3.2 and 40mBq\\/l for

F. Gharbi; S. Baccouche; W. Abdelli; M. Samaali; M. Oueslati; A. Trabelsi

2010-01-01

460

BTD building uranium mass balance study  

SciTech Connect

Fifteen test firings of depleted uranium (DU) munitions were made during the qualification study of the new target building at the BTD Range operated by the US Army Combat Systems Test Activity (CSTA) at Aberdeen Proving Ground, Maryland. Following these test firings, the total mass and mass distribution of DU inside the BTD facility was determined to define decontamination requirements for the new target building. 4 references, 17 figures, 17 tables.

Sutter, S.L.; Johnston, J.W.; Glissmeyer, J.A.; Athey, G.F.

1985-01-01

461

The CZTU uranium concentration analysis code  

SciTech Connect

A {sup 235}U analysis code, CZTU, has been written that can non- destructively evaluate the percentage of {sup 235}U in a uranium sample from the analysis of the emitted gamma rays. This code utilizes gamma spectra measured from room temperature Cadmium Zinc Telluride (CdZnTe or CZT) detectors. It has an accuracy midway between that obtained with sodium iodide and germanium crystal detectors. This report describes how to use the code, some results, limitations and design considerations.

Clark, D., LLNL

1998-07-17

462

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

Uranium contamination of the subsurface has remained a persistent problem plaguing remedial design at sites across the U.S. that were involved with production, handling, storage, milling, and reprocessing of fissile uranium for both civilian and defense related purposes. Remediation efforts to date have relied upon excavation, pump-and-treat, or passive remediation barriers (PRB?s) to remove or attenuate uranium mobility. Documented cases convincingly demonstrate that excavation and pump-and-treat methods are ineffective for a number of highly contaminated sites. There is growing concern that use of conventional PRB?s, such as zero-valent iron, are a temporary solution to a problem that will persist for thousands of years. Alternatives to the standard treatment methods are therefore warranted. The core objective of our research is to demonstrate that a phosphorous amendment strategy will result in a reduction of dissolved uranium to below the proposed drinking water standard. Our hypothesis is that long-chain polyphosphate compounds forestall precipitation of sparingly soluble uranyl phosphate compounds, which is key to preventing fouling of wells at the point of injection. Our other fundamental objective is to synthesize and correctly characterize the uranyl phosphate phases that form in the geochemical conditions under consideration. This report summarizes work conducted at the University of Notre Dame through November of 2003 under DOE grant DE-FG07-02ER63489, which has been funded since September, 2002. The objectives at Notre Dame are development of synthesis techniques for uranyl phosphate phases, together with detailed structural and chemical characterization of the myriad of uranyl phosphate phases that may form under geochemical conditions under consideration.

Burns, Peter C.

2005-06-01

463

Thermal stabilization of uranium mill tailings  

Microsoft Academic Search

The treatment of uranium mill tailings by high-temperature sintering (>1050°C) has been investigated as a means of controlling the release of ²²²Rn and leachable contaminants. Thermal stabilization in laboratory trials at 1200°C reduced the radon emanation of various tailings by factors ranging from 37 to 1400 depending on the mineralogy of the tailings. The leachability of most contaminants (e.g., Al,

David R. Dreesen; Edward J. Cokal; Lawrence E. Wangen; Joel M. Williams; Edward F. Thode

1984-01-01

464

Uranium-mill-tailings conditioning technology  

Microsoft Academic Search

Conditioning of uranium mill tailings involves the physico-chemical alteration of tailings to remove or immobilize mobile radionuclides and toxic trace elements before disposal in a repository. The principal immobilization approach under investigation is sntering tailings at high temperatures (1100 to 1200°C) to radically alter the structure of tailings. This thermal stabilization at 1200°C reduced radon emanation power for tailings sands

D. R. Dreesen; E. J. Cokal; P. D. OBrien; E. F. Thode; L. E. Wangen; J. M. Williams

1982-01-01

465

Process for uranium separation and preparation of UO. 2NH. 2HF. [Effluents from UF. -->. UO conversion  

Microsoft Academic Search

A process for treating the aqueous effluents that are produced in converting gaseous UF (uranium hexafluoride) into solid UO (uranium dioxide) by way of an intermediate (NH) UO (CO) (''AUC'' Compound) is disclosed. These effluents, which contain large amounts of NH\\/sup +\\/, CO\\/sup 2 -\\/, F⁻, and a small amount of U are mixed with HSO (sulfuric acid) in order

Dokuzoguz

1976-01-01

466

Colloids generation from metallic uranium fuel  

SciTech Connect

The possibility of colloid generation from spent fuel in an unsaturated environment has significant implications for storage of these fuels in the proposed repository at Yucca Mountain. Because colloids can act as a transport medium for sparingly soluble radionuclides, it might be possible for colloid-associated radionuclides to migrate large distances underground and present a human health concern. This study examines the nature of colloidal materials produced during corrosion of metallic uranium fuel in simulated groundwater at elevated temperature in an unsaturated environment. Colloidal analyses of the leachates from these corrosion tests were performed using dynamic light scattering and transmission electron microscopy. Results from both techniques indicate a bimodal distribution of small discrete particles and aggregates of the small particles. The average diameters of the small, discrete colloids are {approximately}3--12 nm, and the large aggregates have average diameters of {approximately}100--200 nm. X-ray diffraction of the solids from these tests indicates a mineral composition of uranium oxide or uranium oxy-hydroxide.

Metz, C.; Fortner, J.; Goldberg, M.; Shelton-Davis, C.

2000-07-20

467

Grouting of uranium mill tailings piles  

SciTech Connect

A program of remedial action was initiated for a number of inactive uranium mill tailings piles. These piles result from mining and processing of uranium ores to meet the nation's defense and nuclear power needs and represent a potential hazard to health and the environment. Possible remedial actions include the application of covers to reduce radon emissions and airborne transport of the tailings, liners to prevent groundwater contamination by leachates from the piles, physical or chemical stabilization of the tailings, or moving the piles to remote locations. Conventional installation of liners would require excavation of the piles to emplace the liner; however, utilization of grouting techniques, such as those used in civil engineering to stabilize soils, might be a potential method of producing a liner without excavation. Laboratory studies on groutability of uranium mill tailings were conducted using samples from three abandoned piles and employing a number of particulate and chemical grouts. These studies indicate that it is possible to alter the permeability of the tailings from ambient values of 10/sup -3/ cm/s to values approaching 10/sup -7/ cm/s using silicate grouts and to 10/sup -8/ cm/s using acrylamide and acrylate grouts. An evaluation of grouting techniques, equipment required, and costs associated with grouting were also conducted and are presented. 10 references, 1 table.

Boegly, W.J. Jr.; Tamura, T.; Williams, J.D.

1984-03-01

468

National uranium resource evaluation: Billings Quadrangle, Montana  

SciTech Connect

Five environments in the Billings Quadrangle are favorable for the occurrence of uranium deposits that could contain at least 100 tons U/sub 3/O/sub 8/ in rocks that have an average grade of not less than 100 ppM U/sub 3/O/sup 8/. The Mississippian Madison Limestone of the Pryor Mountains, a favorable environment for limestone-type deposits, contains a small mining district that has produced over 110,000 pounds of U/sub 3/O/sub 8/. The Cambrian Flathead Sandstone along the eastern flanks of the Beartooth Mountains is favorable for unconformity-related deposits; the area contains several uranium occurrences. The Pennsylvanian Tensleep Sandstone along the southern flanks of the Pryor Mountains is a favorable environment for Texas roll-type deposits because of lithology, structure, depositional environment, and proximity to a potential source area. The Cretaceous Lakota and Virgelle Sandstones exhibit the lithology, permeability, and volume to host sandstone-type uranium deposits. All other environments in the quadrangle are unfavorable or unevaluated.

Warchola, R.J.; Stockton, T.J.

1982-05-01

469

Determination of uranium in natural waters  

USGS Publications Warehouse

A method is described for the determination of very low concentrations of uranium in water. The method is based on the fluorescence of uranium in a pad prepared by fusion of the dried solids from the water sample with a flux of 10 percent NaF 45.5 percent Na2CO3 , and 45.5 percent K2CO3 . This flux permits use of a low fusion temperature and yields pads which are easily removed from the platinum fusion dishes for fluorescence measurements. Uranium concentrations of less than 1 microgram per liter can be determined on a sample of 10 milliliters, or less. The sensitivity and accuracy of the method are dependent primarily on the purity of reagents used, the stability and linearity of the fluorimeter, and the concentration of quenching elements in the water residue. A purification step is recommended when the fluorescence is quenched by more than 30 percent. Equations are given for the calculation of standard deviations of analyses by this method. Graphs of error functions and representative data are also included.

Barker, Franklin Butt; Johnson, J. O.; Edwards, K. W.; Robinson, B. P.

1965-01-01

470

Health concerns in uranium mining and milling  

SciTech Connect

Mortality of uranium miners form both lung cancer and other respiratory diseases is strongly dependent on exposure to radon daughters, cigarette smoking and height. Lung cancer among 15 different mining groups (uranium, iron, led, zinc) was analyzed to determine what factors influence incidence and the induction-latent period. At low exposure or exposure rates, alpha radiation is more efficient in inducing lung cancer, producing an upward convex exposure-response curve. The induction-latent period is shortened by increased age at start of mining, by cigarette smoking and by high exposure rates. For a follow-up period of 20 to 25 years, the incidence increases with age at start of mining, with magnitude of exposure and with amount of cigarette smoking. Instead of extrapolating downward from high exposures to estimate risk at low levels, it is suggested that it might be more appropriate to use cancer rates associated with background radiation as the lowest point on the exposure-response curve. Although health risks are much greater in uranium mines than mills, there is some health risk in the mills from long-lived radioactive materials.

Archer, V.E.

1981-07-01

471

X-Ray Emission from "Uranium" Stars  

NASA Technical Reports Server (NTRS)

The project aims to secure XMM observations of two targets with extremely low abundances of the majority of heavy elements (e.g., log[Fe/H] $\\sim$-4), but that show absorption lines of uranium. The presence of an r-process element such as uranium requires a binary star system in which the companion underwent a supernova explosion. A binary star system raises the distinct possibility of the existence of a compact object, most likely a neutron star, in the binary, assuming it survived the supernova blast. The presence of a compact object then suggests X-ray emission if sufficient matter accretes to the compact object. The observations were completed less than one year ago following a series of reobservations to correct for significant flaring that occurred during the original observations. The ROSAT all-sky survey was used to report on the initial assessment of X-ray emission from these objects; only upper limits were reported. These upper limits were used to justify the XMM observing time, but with the expectation that upper limits would merely be pushed lower. The data analysis hinges critically on the quality and degree of precision with which the background is handled. During the past year, I have spent some time learning the ins and outs of XMM data analysis. In the coming year, I can apply that learning to the analysis of the 'uranium' stars.

Schlegel, Eric; Mushotzky, Richard (Technical Monitor)

2005-01-01

472

Monitoring genotoxic exposure in uranium miners  

SciTech Connect

Recent data from deep uranium mines in Czechoslovakia indicated that in addition to radon daughter products, miners are also exposed to chemical mutagens. Mycotoxins were identified as a possible source of mutagenicity present in the mines. Various methods of biomonitoring were used to examine three groups of miners from different uranium mines. Cytogenetic analysis of peripheral lymphocytes, unscheduled DNA synthesis (UDS) in lymphocytes, and lipid peroxidation (LPO) in both plasma and lymphocytes were studied on 66 exposed miners and 56 controls. Throat swabs were taken from 116 miners and 78 controls. Significantly increased numbers of aberrant cells were found in all groups of miners, as well as decreased UDS values in lymphocytes and increased LPO plasma levels in comparison to controls. Molds were detected in throat swabs from 27% of miners, and 58% of these molds were embryotoxic. Only 5% of the control samples contained molds and none of them was embryotoxic. The following mycotoxins were isolated from miners' throat swab samples: rugulosin, sterigmatocystin, mycophenolic acid, brevianamid A, citreoviridin, citrinin, penicilic acid, and secalonic acid. These data suggest that mycotoxins are a genotoxic factor affecting uranium miners.

Sram, R.J.; Binkova, B.; Dobias, L.; Roessner, P.T.; Topinka, J.; Vesela, D.; Vesely, D.; Stejskalova, J.; Bavorova, H.; Rericha, V. (Institute of Experimental Medicine, Prague (Czechoslovakia))

1993-03-01

473

National Uranium Resource Evaluation: Escalante Quadrangle, Utah  

SciTech Connect

Seven areas favorable for the occurrence of uranium deposits meet the minimum size and grade requirements of the National Uranium Resource Evaluation of the US Department of Energy in the Escalante 1/sup 0/ x 2/sup 0/ Quadrangle, South-Central Utah. Five areas identified in the Late Jurassic Salt Wash Member of the Morrison Formation are: the Henry Mountains mineral belt, and the Bitter Creek, Cat Pasture, Carcass Canyon, and Fiftymile Point areas. The evaluation of these areas was based on the presence of the following features: fluvial sandstones deposited by low-energy streams; actively subsiding synclines; paleostream transport directions approximately perpendicular to the trend of the paleofolds; presence of favorable gray lacustrine mudstone; and known uranium occurrences associated with the favorable gray mudstones. Four favorable areas identified in the Late Triassic Chinle Formation are the White Canyon-Elk Ridge, Dirty Devil-Orange Cliffs, Monument Valley, and the Greater Circle Cliffs subareas. These areas were identified as favorable on the basis of the sandstone-to-shale ratio for the Chinle Formation, and the geographic distribution of the Petrified Forest Member of the Chinle.

Peterson, F.; Campbell, J.A.; Franczyk, K.J.; Lupe, R.D.

1982-09-01

474

Critical analysis of world uranium resources  

USGS Publications Warehouse

The U.S. Department of Energy, Energy Information Administration (EIA) joined with the U.S. Department of the Interior, U.S. Geological Survey (USGS) to analyze the world uranium supply and demand balance. To evaluate short-term primary supply (015 years), the analysis focused on Reasonably Assured Resources (RAR), which are resources projected with a high degree of geologic assurance and considered to be economically feasible to mine. Such resources include uranium resources from mines currently in production as well as resources that are in the stages of feasibility or of being permitted. Sources of secondary supply for uranium, such as stockpiles and reprocessed fuel, were also examined. To evaluate long-term primary supply, estimates of uranium from unconventional and from undiscovered resources were analyzed. At 2010 rates of consumption, uranium resources identified in operating or developing mines would fuel the world nuclear fleet for about 30 years. However, projections currently predict an increase in uranium requirements tied to expansion of nuclear energy worldwide. Under a low-demand scenario, requirements through the period ending in 2035 are about 2.1 million tU. In the low demand case, uranium identified in existing and developing mines is adequate to supply requirements. However, whether or not these identified resources will be developed rapidly enough to provide an uninterrupted fuel supply to expanded nuclear facilities could not be determined. On the basis of a scenario of high demand through 2035, 2.6 million tU is required and identified resources in operating or developing mines is inadequate. Beyond 2035, when requirements could exceed resources in these developing properties, other sources will need to be developed from less well-assured resources, deposits not yet at the prefeasibility stage, resources that are currently subeconomic, secondary sources, undiscovered conventional resources, and unconventional uranium supplies. This reports analysis of 141 mines that are operating or are being actively developed identifies 2.7 million tU of in-situ uranium resources worldwide, approximately 2.1 million tU recoverable after mining and milling losses were deducted. Sixty-four operating mines report a total of 1.4 million tU of in-situ RAR (about 1 million tU recoverable). Seventy-seven developing mines/production centers report 1.3 million tU in-situ Reasonably Assured Resources (RAR) (about 1.1 million tU recoverable), which have a reasonable chance of producing uranium within 5 years. Most of the production is projected to come from conventional underground or open pit mines as opposed to in-situ leach mines. Production capacity in operating mines is about 76,000 tU/yr, and in developing mines is estimated at greater than 52,000 tU/yr. Production capacity in operating mines should be considered a maximum as mines seldom produce up to licensed capacity due to operational difficulties. In 2010, worldwide mines operated at 70 percent of licensed capacity, and production has never exceeded 89 percent of capacity. The capacity in developing mines is not always reported. In this study 35 percent of developing mines did not report a target licensed capacity, so estimates of future capacity may be too low. The Organisation for Economic Co-operation and Developments Nuclear Energy Agency (NEA) and International Atomic Energy Agency (IAEA) estimate an additional 1.4 million tU economically recoverable resources, beyond that identified in operating or developing mines identified in this report. As well, 0.5 million tU in subeconomic resources, and 2.3 million tU in the geologically less certain inferred category are identified worldwide. These agencies estimate 2.2 million tU in secondary sources such as government and commercial stockpiles and re-enriched uranium tails. They also estimate that unconventional uranium supplies (uraniferous phosphate and black shale deposits) may contain up to 7.6 million tU. Although unconventional resources are currently subeconomic, the improvement of extraction te

Hall, Susan; Coleman, Margaret

2013-01-01

475

Exploration for uranium deposits, Grants mineral belt  

SciTech Connect

Uranium ore deposits in the Grants mineral belt, New Mexico, occur in fluvial sandstones in the Morrison Formation (Jurassic). Uranium mineralization is concentrated by a dark-gray to black substance that has been identified as humate, which is derived from decaying vegetation. Black ore is truncated by overlying sandstone in at least three ore deposits, documenting an early age for mineralization. Ore deposits in the Grants mineral belt vary greatly in size and shape, tend to occur in clusters, and often present difficult drill targets. Current exploration is largely a matter of drilling in stages to distinguish favorable from unfavorable ground on a wide spacing, to seek mineralization in favorable ground, and to conduct close-spaced drilling in mineralized areas. Criteria for favorability differ among exploration groups but generally include 1) presence of a host sandstone, 2) anomalous mineralization, 3) color of the host rock, 4) presence of carbonaceous matter, and 5) position of the area relative to mineralized trends. A description of the drilling sequence, from ore discovery to the development of a mine at the Johnny M deposit (in the east part of the Ambrosia Lake district), exemplifies the problem of predicting where orebodies may occur. A study of the drill data at the Johnny M indicates the uranium ore is not related to specific geologic features other than humate, which is commonly associated with coalified plant fragments in mudstone-rich parts of the host sandstone.

Fitch, D.C.

1980-01-01

476

Sandstone Uranium Deposits in the United States: A Review of the History, Distribution, Genesis, Mining Areas, and Outlook (69 References).  

National Technical Information Service (NTIS)

Sandstone uranium deposits account for about 94 percent of uranium reserves in the United States. Most sandstone uranium districts had been found by the mid-1950s in response to incentives promulgated by the US Atomic Energy Commission. Principal