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1

Conversion of uranium hexafluoride to uranium dioxide  

Microsoft Academic Search

This patent describes a process for the preparation of uranium dioxide, comprising: reacting, in the vapor phase, uranium hexafluoride with steam to produce submicron uranyl fluoride powder; simultaneously fluidizing a bed of a uranium oxide material having a uranium to oxygen ratio of from about 1:2.0 to about 1:2.67 with a mixture of steam, hydrogen and an inert gas at

Urza

1989-01-01

2

Production of uranium dioxide  

Microsoft Academic Search

A continuous, four stage fluidized bed process for converting uranium hexafluoride (UF) to ceramic-grade uranium dioxide (UO) powder suitable for use in the manufacture of fuel pellets for nuclear reactors is disclosed. The process comprises the steps of first reacting UF with steam in a first fluidized bed, preferably at about 550°C, to form solid intermediate reaction products UOF, UO

J. E. Hart; D. L. Shuck; W. L. Lyon

1977-01-01

3

Conversion of uranium hexafluoride to uranium dioxide  

SciTech Connect

This patent describes a process for the preparation of uranium dioxide, comprising: reacting, in the vapor phase, uranium hexafluoride with steam to produce submicron uranyl fluoride powder; simultaneously fluidizing a bed of a uranium oxide material having a uranium to oxygen ratio of from about 1:2.0 to about 1:2.67 with a mixture of steam, hydrogen and an inert gas at temperatures in the range of about 580/sup 0/C to about 700/sup 0/C; introducing the submicron uranyl fluoride powder produced from the reaction of uranium hexafluoride and steam at the top of the fluidized bed of uranium oxide material; whereby the submicron uranyl fluoride powder is agglomerated, densified, fluidized, defluorinated and reduced to a fluoride-containing uranium oxide material having a uranium-to-oxygen ratio of from about 1:2.0 to about 1:2.67 and containing minor amounts of fluoride; removing the fluoride-containing material from the fluidized bed at a rate sufficient to maintain the level of the fluidized bed substantially constant; and contacting the removed material with hydrogen and steam at temperatures in the range of about 600/sup 0/C, whereby uranium dioxide essentially free of fluoride is obtained.

Urza, I.J

1989-05-16

4

Process for producing uranium dioxide  

Microsoft Academic Search

This patent describes a process for the production of uranium dioxide powder by calcining a uranium compound, whereby an off-gas stream is produced by an ammonium diuranate calciner which contains ammonium fluoride vapor and uranium-containing particulate matter. The improvement comprises: maintaining the off-gas stream after discharge from the calciner at an elevated temperature in excess of about 340°C; passing the

Noe

1987-01-01

5

URANIUM DIOXIDE NUCLEAR FUEL  

Microsoft Academic Search

Nuclear fuel making is a new and still not-too-large addition to the ; chemical industry. But fuel producers are optimistic, look more to future needs ; than to current requirements. Uranium dioride is the most popular nuclear fuel ; today, and will probably stuy in first place for some time. Mallinokrodt Nuclear ; was the first commercial UO producer. At

Chester Placek; Edward North

1960-01-01

6

FLAME DENITRATION AND REDUCTION OF URANIUM NITRATE TO URANIUM DIOXIDE  

DOEpatents

A process is given for converting uranyl nitrate solution to uranium dioxide. The process comprises spraying fine droplets of aqueous uranyl nitrate solution into a hightemperature hydrocarbon flame, said flame being deficient in oxygen approximately 30%, retaining the feed in the flame for a sufficient length of time to reduce the nitrate to the dioxide, and recovering uranium dioxide. (AEC)

Hedley, W.H.; Roehrs, R.J.; Henderson, C.M.

1962-06-26

7

Process for manufacturing uranium dioxide powder  

Microsoft Academic Search

A process is described for manufacturing uranium dioxide powder which comprises forming fine uranium dioxide powder having a high sinterability and coarse uranium dioxide powder having a low sinterability continuously in one process by changing periodically the precipitation condition of the ammonium diuranate under the same condition of calcining and reducing of the ammonium diuranate. The thus obtained mixture of

Sh. I. Hasegawa; M. Sekine; E. Takano

1985-01-01

8

LOW-TEMPERATURE MAGNETIC STUDIES OF URANIUM HYDRIDE, URANIUM DEUTERIDE, AND URANIUM DIOXIDE  

Microsoft Academic Search

A study of magnetization as a function of temperature and magnetic field ; has been carried out for uranium hydride, uranium deuteride, and uranium dioxide ; at temperatures from 300 deg K to 1.3 deg K and in magnetic fields from 60,000 ; gauss down to zero field. The apparent saturation magnetization for the samples ; of beta-uranium hydride used

Warren Henry

1958-01-01

9

Thermodynamic properties of uranium dioxide  

NASA Astrophysics Data System (ADS)

In order to provide reliable and consistent data on the thermophysical properties of reactor materials for rector safety studies, revision was prepared for the thermodynamic properties of the uranium dioxide portion of the fuel property section of the report Properties for Liquid Metal Fast Breeder Reactors Safety Analysis. International agreement was reached on a vapor pressure equation for the total pressure over UO2, for the calculation of enthalpy and heat capacity, and a phase change at 2670 K. 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

10

Quadrupolar Waves in Uranium Dioxide  

NASA Astrophysics Data System (ADS)

In presence of active orbital degrees of freedom, elementary excitations around a broken-symmetry state may include multipolar waves, but none of these exotic dispersive excitation branches has ever been identified. We show that quadrupolar waves constitute a major component of the dynamics of uranium dioxide in its magnetoquadrupolar ordered phase, and that many unexplained features in existing inelastic neutron scattering data, including a whole excitation branch, are associated with these propagating quadrupolar fluctuations. Our model permits us to separate the role of Jahn-Teller and superexchange mechanisms as sources of quadrupolar interactions.

Carretta, S.; Santini, P.; Caciuffo, R.; Amoretti, G.

2010-10-01

11

Low-Temperature Magnetic Studies of Uranium Hydride, Uranium Deuteride, and Uranium Dioxide  

Microsoft Academic Search

A study of magnetization as a function of temperature and magnetic field has been carried out for uranium hydride, uranium deuteride, and uranium dioxide at temperatures from 300K to 1.3K and in magnetic fields from 60 000 gauss down to zero field. The apparent saturation magnetization for the samples of beta-uranium hydride used is 1.18+\\/-0.03 Bohr magnetons per atom of

Warren E. Henry

1958-01-01

12

Uranium  

Microsoft Academic Search

\\u000a Uranium compounds have been used as colorants since Roman times (Caley, 1948). Uranium was discovered as a chemical element\\u000a in a pitchblende specimen by Martin Heinrich Klaproth, who published the results of his work in 1789. Pitchblende is an impure uranium oxide, consisting partly of the most reduced oxide uraninite (UO2) and partly of U3O8. Earlier mineralogists had considered this

Ingmar Grenthe; Janusz Drozdzynski; Takeo Fujino; Edgar C. Buck; Thomas E. Albrecht-Schmitt; Stephen F. Wolf

2011-01-01

13

Oxidation of Uranium Dioxide (UO2)  

Microsoft Academic Search

IN connexion with earlier investigations on uranium oxides in this Institute, it was observed that uranium dioxide (UO2) can react with oxygen at so low a temperature as 120 C. To obtain more exact information about this low-temperature oxidation of UO2, the oxide was heated in purified oxygen at different temperatures from 100 to 265 C. and the reaction products

Fredrik Genvold; Haakon Haraldsen

1948-01-01

14

URANIUM DIOXIDE AS A NUCLEAR FUEL  

Microsoft Academic Search

Uranium dioxide is the most important and the most utilized high-; temperature reactor fuel. The properties of this material are presented. The ; fabrication process and behavior of UO during irradiation are discussed. ; (auth);

Seidl

1963-01-01

15

Exposure to Subcutaneously Implanted Uranium Dioxide Impairs Bone Formation  

Microsoft Academic Search

The introduction of uranium particles into subcutaneous tissue is a risk that affects workers engaged in the extraction, purification, and manufacture of uranium, as well as soldiers who are wounded with uranium shrapnel. The authors evaluated the effect of an internal source of an insoluble form of uranium on bone. Uranium dioxide powder (0.125 gm\\/kg body weight) was implanted subcutaneously

Paula L. Daz Sylvester; Ricardo Lopez; Angela M. Ubios; Rmulo L. Cabrini

2002-01-01

16

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

17

Uranium  

Microsoft Academic Search

By 1911, the atomic weight of uranium had been refined to 238.5 (Gmelin, vol. A2, 1980a). The natural isotope 235U was discovered in 1935 by mass spectrometry. The artificial isotope 239U, which is the precursor of 239Np and 239Pu, was postulated and identified by Hahn and coworkers (Hahn et al., 1937; Meitner et al., 1937) as a 23 min half-life

Ingmar Grenthe; Janusz Dro?d?yn?ski; Takeo Fujino; Edgar C. Buck; Thomas E. Albrecht-Schmitt; Stephen F. Wolf

2006-01-01

18

Light attrition of uranium dioxide powder  

Microsoft Academic Search

Sinterable uranium dioxide powders prepared through the ammonium diuranate route are prone to agglomeration causing difficulty in compaction and sintering. UO2 powder after light (short duration and low ball to charge ratio) attrition has been found to require lower compaction pressures and resulted in higher yields after sintering and finish grinding. Details of an in-house-built attritor are given. Experimental results

Palanki Balakrishna; B Narasimha Murty; D. V Ratnam; M Anuradha; C Ganguly

2003-01-01

19

Creep deformation of stoichiometric uranium dioxide  

Microsoft Academic Search

The plastic behavior of sintered uranium dioxide of stoichiometric ; composition was studied using a creepin-bending method. The range of temperature ; from 1250 to 1400 deg C and stresses from 700 to 16,000 psi were covered in the ; investigation. Expressions describing the dependence of steady-state creep rates ; on stress and temperature were developed. Materials possessing sintered ;

W. M. Armstrong; W. R. Irvine; R. H. Martinson

1962-01-01

20

METHOD FOR THE ELECTROLYTIC POLISHING OF URANIUM DIOXIDE  

Microsoft Academic Search

A method for the electrolytic polishing and etching of uranium dioxide ; was studied. It was applied to the micrographic examination of fritted uranium ; oxide pellets. A detailed study was made of the microstructure. (tr-auth);

A. Portnoff; H. Frisby

1960-01-01

21

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

22

Theory of Helium Dissolution in Uranium Dioxide. I. Interatomic Forces in Uranium Dioxide  

Microsoft Academic Search

Knowledge of the nature of the interatomic forces in uranium dioxide is required for theoretical treatment of phenomena such as radiation damage, adsorption, and gas solubility. The van der Waals and repulsive forces are of particular interest, for these interactions govern the behavior of neutral species in the crystal. The KirkwoodMuller expression for the coefficients of the 1\\/rn dispersion forces

Donald R. Olander

1965-01-01

23

The growth of fission gas bubbles in irradiated uranium dioxide  

Microsoft Academic Search

The growth of fission gas bubbles from supersaturated solution in irradiated uranium dioxide has been studied by electron microscopy under isothermal annealing conditions between 1300 and 1500C. Measurements of the kinetics of bubble growth have enabled the diffusion coefficients of atomic xenon and krypton in irradiated uranium dioxide to be determined. The diffusion coefficients obtained may be expressed by the

R. M. Cornell

1969-01-01

24

Synthesis of uranium fluorides from uranium dioxide with ammonium bifluoride and ammonolysis of uranium fluorides to uranium nitrides  

NASA Astrophysics Data System (ADS)

This work presents the chemical conversion of uranium oxides to uranium fluorides, and their subsequent conversion to uranium nitrides. Uranium dioxide reacts with ammonium bifluoride at 20C to form compound in the ammonium-uranium fluoride chemical system. This reaction occurs between solid uranium dioxide at the surface of the particles and ammonium fluoride vapor. A shrinking-sphere model demonstrated surface reaction kinetics, not mass transport by diffusion through the product layer, limit the reaction rate when the starting material consists of 100 mum uranium dioxide particles. Powder x-ray diffraction showed the reaction to be complete within 8 hours, with (NH4) 4UF8 the reaction product. High-resolution electron microcopy revealed the product is largely amorphous on a micrometer-scale, but contains well-formed crystal domains on the order of 10x10 nm. X-ray diffraction showed the reaction progresses though beta-NH4UF5, delta-(NH 4)2UF6, and gamma-(NH4)2UF6 intermediate phases before finally forming (NH4)4UF 8. Modeling the system as a series of first-order reaction suggested a fourth intermediate, possibly UF4, is likely to occur. The reaction of (NH4)4UF8 with ammonia gas at 800C forms alpha-U2N3/UN2 solid solution products with a composition of UN1.83. The x-ray powder diffraction pattern of this product is the fcc pattern commonly referenced as that of UN2 and the lattice parameter was 0.53050 nm. Surface area increased by a factor of ten during ammonolysis, consistent with the action of a hydriding agent. The alpha-U2N 3/UN2 solid solution system formed contained 1 wt% UO 2 as an impurity. Upon subsequent heating to 1150C for 4.5 hours under argon, the nitride sample formed UN with a UO2 impurity of 9 wt%. Based on the HRTEM images, oxidation in the UN product appears to be limited to within 20 nm of particle surfaces and grain boundaries.

Yeamans, Charles Burnett

25

Synthesis of colloidal uranium-dioxide nanocrystals.  

PubMed

In this paper, we have developed an organic-phase synthesis method for producing size-controlled, nearly monodispersed, colloidal uranium-dioxide nanocrystals. These UO2 nanocrystals are potentially important to applications such as nuclear fuel materials, catalysts, and thermopower materials. In addition, we have systematically mapped out the functions of the solvents (oleic acid, oleylamine, and 1-octadecene) in the synthesis, and we found that N-(cis-9-octadecenyl)oleamide-a product of the condensation of oleic acid and oleylamine-can substantially affect the formation of UO2 nanocrystals. Importantly, these results provide fundamental insight into the mechanisms of UO2 nanocrystal synthesis. Moreover, because a mixture of oleic acid and oleylamine has been widely used in synthesizing a variety of high-quality metal or metal-oxide nanocrystals, the results herein should also be important for understanding the detailed mechanisms of these syntheses. PMID:17177400

Wu, Huimeng; Yang, Yongan; Cao, Y Charles

2006-12-27

26

Irradiation of Tzm: Uranium Dioxide Fuel Pin at 1700 K.  

National Technical Information Service (NTIS)

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...

G. E. Mcdonald

1973-01-01

27

Calculation of oxygen isotope fractionation between uranium dioxide, uranium trioxide and water  

Microsoft Academic Search

Reduced partition function ratios (r.p.f.r) for uranium dioxide and uranium trioxide are calculated using selected crystal field models for optical modes and Debye functions for acoustic modes at temperatures ranging from 0 to 1000C. The contribution of the acoustic modes is negligibly small in the calculated values of r.p.f.r. in all temperature ranges. The uncertainty of the r.p.f.r. is calculated

Keiko Hattori; Stanislaw Halas

1982-01-01

28

An analysis of the impact of having uranium dioxide mixed in with plutonium dioxide  

SciTech Connect

An assessment was performed to show the impact on airborne release fraction, respirable fraction, dose conversion factor and dose consequences of postulated accidents at the Plutonium Finishing Plant involving uranium dioxide rather than plutonium dioxide.

MARUSICH, R.M.

1998-10-21

29

New method for conversion of uranium hexafluoride to uranium dioxide  

SciTech Connect

Five different methods for conversion of UF/sub 6/ to ceramic-grade UO/sub 2/ powder have been developed to industrial scale. Two of them, the ammonium diuranate (ADU) and AUC processes, are based on precipitation of uranium compounds from aqueous solutions. The other three follow a dry route in which UF/sub 6/ is hydrolyzed and reduced by steam and hydrogen using fluidized bed techniques, rotating kilns, or flame chemistry methods. The ADU process has the advantage of flexible product powder characteristics, while disadvantages include a large quantity of waste, low powder fluidity, and a complicated process. On the other hand, the dry process using fluidized-bed techniques has the advantages of hydrofluoric acid recovery, a free-flowing powder, and process simplicity, but the disadvantages of poorer ceramic properties for the product. The new method developed at Mitsubishi Metal Corp. is a semidry process, which has well-balanced merits over the ADU process and the dry process using fluidized-bed techniques. This process is very attractive from powder characteristics, process simplicity, and waste reduction.

Nakabayashi, S.; Suzuki, M.; Tanaka, H.

1987-01-01

30

Radiative properties of uranium dioxide near its melting points  

SciTech Connect

A new technique for measuring radiative properties of nuclear fuel materials at high temperatures has been developed. The technique is based on pulse diffuse optical probing of the sample surface and on pyroreflectometry used in measuring radiative properties of refractory materials during laser heating or cooling. Pulse diffuse optical probing of the sample has been realized for the first time in subsecond pyrometry of the open surface heated by laser radiation. Such a procedure of sample irradiation during sample laser heating or cooling enables reflectivity and emissivity measurements near high temperature phase transitions to be performed in spite of possible sharp changes of the reflection indicatrix at phase transitions in the investigated material. With the method developed in this study, the spectral emissivity and reflectivity of uranium dioxide near its premelting and melting points have been measured. It has been found that condensation of the vapor plume formed above the sample during laser heating influenced the melting and boiling temperatures of uranium dioxide. The first-order phase transitions in uranium dioxide, such as solid-vapor-solid and liquid-vapor-liquid, have been observed in uranium dioxide for the first time during laser heating. Also, new data on the spectral emissivity of uranium dioxide at a wavelength of 0.644 {micro}m and in the temperature range of 2,000 to 4,200 K are presented.

Salikhov, T.P.; Kan, V.V.; Ronchi, C.

1999-07-01

31

Molecular Beam Study of the Kinetics of the Fluorine--Uranium Dioxide Reaction.  

National Technical Information Service (NTIS)

The kinetics of uranium dioxide fluorination were studied using an experimental system in which a molecular beam of fluorine was directed at a heated uranium dioxide single crystal wafer maintained in high vacuum. Gaseous reaction products desorbed from t...

A. J. Machiels

1976-01-01

32

PREPARATION OF URANIUM DIOXIDE FOR USE IN CERAMIC FUELS. PART III. AMMONIUM DIURANATE REDUCTION STUDIES  

Microsoft Academic Search

Uranium dioxide can be prepared by the reduction of ammonium diuranate ; with hydrogen at elevated temperatures. The results of a study made to define ; the effects of the reduction conditions on the sintered density of the uranium ; dioxide compacts are described. Seven variables which might be expected to ; affect the properties of the uranium dioxide were

A. R. Bancroft; L. C. Watson

1958-01-01

33

Irradiation-induced heterogeneous nucleation in uranium dioxide  

NASA Astrophysics Data System (ADS)

Using classical molecular dynamics simulations, we have studied the first stages of defect cluster formation resulting from 10 keV displacement cascades in uranium dioxide. Nanometre size cavities and dislocation loops are shown to appear as a result of the irradiation process. A specifically designed TEM experiment involving He implanted thin foils have also been carried out to support this modelling work. These results, in conjunction with several other observations taken from the literature of ion implanted or neutron irradiated uranium dioxide, suggest a radiation damage controlled heterogeneous mechanism for insoluble fission product segregation in UO2.

Martin, G.; Garcia, P.; Sabathier, C.; van Brutzel, L.; Dorado, B.; Garrido, F.; Maillard, S.

2010-07-01

34

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

35

Selective Extraction of Uranium from Liquid or Supercritical Carbon Dioxide  

SciTech Connect

Current liquid-liquid extraction processes used in recycling irradiated nuclear fuel rely on (1) strong nitric acid to dissolve uranium oxide fuel, and (2) the use of aliphatic hydrocarbons as a diluent in formulating the solvent used to extract uranium. The nitric acid dissolution process is not selective. It dissolves virtually the entire fuel meat which complicates the uranium extraction process. In addition, a solvent washing process is used to remove TBP degradation products, which adds complexity to the recycling plant and increases the overall plant footprint and cost. A liquid or supercritical carbon dioxide (l/sc -CO2) system was designed to mitigate these problems. Indeed, TBP nitric acid complexes are highly soluble in l/sc -CO2 and are capable of extracting uranium directly from UO2, UO3 and U3O8 powders. This eliminates the need for total acid dissolution of the irradiated fuel. Furthermore, since CO2 is easily recycled by evaporation at room temperature and pressure, it eliminates the complex solvent washing process. In this report, we demonstrate: (1) A reprocessing scheme starting with the selective extraction of uranium from solid uranium oxides into a TBP-HNO3 loaded Sc-CO2 phase, (2) Back extraction of uranium into an aqueous phase, and (3) Conversion of recovered purified uranium into uranium oxide. The purified uranium product from step 3 can be disposed of as low level waste, or mixed with enriched uranium for use in a reactor for another fuel cycle. After an introduction on the concept and properties of supercritical fluids, we first report the characterization of the different oxides used for this project. Our extraction system and our online monitoring capability using UV-Vis absorbance spectroscopy directly in sc-CO2 is then presented. Next, the uranium extraction efficiencies and kinetics is demonstrated for different oxides and under different physical and chemical conditions: l/sc -CO2 pressure and temperature, TBP/HNO3 complex used, reductant or complexant used for selectivity, and ionic liquids used as supportive media. To complete the extraction and recovery cycle, we then demonstrate uranium back extraction from the TBP loaded sc-CO2 phase into an aqueous phase and the characterization of the uranium complex formed at the end of this process. Another aspect of this project was to limit proliferation risks by either co-extracting uranium and plutonium, or by leaving plutonium behind by selectively extracting uranium. We report that the former is easily achieved, since plutonium is in the tetravalent or hexavalent oxidation state in the oxidizing environment created by the TBP-nitric acid complex, and is therefore co-extracted. The latter is more challenging, as a reductant or complexant to plutonium has to be used to selectively extract uranium. After undertaking experiments on different reducing or complexing systems (e.g., AcetoHydroxamic Acid (AHA), Fe(II), ascorbic acid), oxalic acid was chosen as it can complex tetravalent actinides (Pu, Np, Th) in the aqueous phase while allowing the extraction of hexavalent uranium in the sc-CO2 phase. Finally, we show results using an alternative media to commonly used aqueous phases: ionic liquids. We show the dissolution of uranium in ionic liquids and its extraction using sc-CO2 with and without the presence of AHA. The possible separation of trivalent actinides from uranium is also demonstrated in ionic liquids using neodymium as a surrogate and diglycolamides as the extractant.

Farawila, Anne F.; O'Hara, Matthew J.; Wai, Chien M.; Taylor, Harry Z.; Liao, Yu-Jung

2012-07-31

36

Temperatures, thermal stresses and displacements in solid uranium dioxide rods  

Microsoft Academic Search

Expressions are derived for the temperatures, stresses and displacements in a solid uranium dioxide fuel rod, the thermal conductivity of which decreases exponentially with temperature. Graphs of the temperatures and displacements are given, and calculation shows that the rod will fracture when the centre-to-surface temperature drop exceeds 80-90 C.

J P Ellington

1960-01-01

37

SELF-REDUCTION OF AMMONIUM DIURANATE TO URANIUM DIOXIDE  

Microsoft Academic Search

The method is designed to transform ammonium diuranate into uranium ; dioxide without having to use any other agent as a reducer. It rests on the fact ; that this reduction can be achieved by the hydrogen produced by the dissociation ; of the ammonia released from the diuranate when heated. The final total reaction ; is (NH)UO yields 2UO

J. D. Pedregal; R. R. Solano

1959-01-01

38

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

39

Helium thermal diffusion in a uranium dioxide matrix  

Microsoft Academic Search

The behavior of helium and its diffusion mechanisms in uranium dioxide significantly impact the possible evolution of the spent fuel matrix in interim storage or in a disposal repository, and are therefore an essential aspect of the R&D, regarding fuel matrix behavior in a closed system. A specific experimental study has been conducted, the first part being devoted to thermal

Danile Roudil; Xavier Deschanels; Patrick Trocellier; Christophe Jgou; Sylvain Peuget; Jean-Michel Bart

2004-01-01

40

VISIBLE AND ULTRAVIOLET ABSORPTION PROPERTIES OF URANIUM DIOXIDE FILMS  

Microsoft Academic Search

Films of uranium dioxide ranging in thickness from 132 to 280 m mu were ; evaporated onto fused silica, annealed at a pressure of 10⁻⁶ mm Hg and 960 ; deg C, and measured for optical absorption between the wavelengths of 210 and 800 ; m mu . A moderately intense band observed at 240 io 500 m mu has

R. J. Ackermann; R. J. Thorn; G. H. Winslow

1959-01-01

41

DECOMPOSITION OF URANIUM DIOXIDE AT ITS MELTING POINT  

Microsoft Academic Search

The fusion of uranium dioxide in an argon gas arc furnace at 2800 plus ; or minus 100 deg C consistently gave lustrous grey metallic-looking products, ; with a gross analytical composition UO\\/sub 2-x\\/ (0.15> r> 0). The oxygen ; deficiency was found to depend on the time duration in the molten state; after ; prolonged fusion a limiting composition

J. S. Anderson; J. O. Sawyer; H. W. Worner; G. M. Willis; M. J. Bannister

1960-01-01

42

Formation energies and swelling of uranium dioxide by point defects  

NASA Astrophysics Data System (ADS)

Hybrid density functional theory is used to study the stability and behavior of rare gases in uranium dioxide. Three insertion sites are considered: the octahedral interstitial position and the oxygen and uranium substitution sites. The optimized lattice constant, the volume variation induced by gaseous atom incorporation, and the defect formation energy are studied for each rare gas. Both lattice constants and formation energies increase with increase in radii of the rare gases. The octahedral interstitial position is the most favorable occupation site. The formation energy is found to be negative only for He at an interstitial site.

Ma, Li; Ray, Asok K.

2012-03-01

43

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 UO 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

44

First principles modeling of stability mechanism of nonstoichiometric uranium dioxide  

Microsoft Academic Search

To understand the stability mechanism of defects in the nonstoichiometric uranium dioxides, first-principles calculations have been performed by PAW-LSDA+U method for various defects clusters formed from interstitial oxygen atoms and the lattice vacancies. Calculations revealed that the cuboctahedron cluster embedded into the crystal UO2 with one O-atom at the center is the most stable configuration among all known clusters including

Ying Chen; Hua Y. Geng; Yasunori Kaneta; Motoyasu Kinoshita; Shuichi Iwata

2010-01-01

45

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

46

PRODUCTION OF URANIUM HEXAFLUORIDE  

Microsoft Academic Search

A process for the production of uranium hexafluoride from the oxides of ; uranium is reported. In accordance with the method, the higher oxides of uranium ; may be reduced to uranium dioxide (UO), the latter converted into uranium ; tetrafluoride by reaction with hydrogen fluoride, and the UF converted to ; UF by reaction with a fluorinating agent, such

1957-01-01

47

An Ab Initio Study of rare gases in uranium dioxide  

NASA Astrophysics Data System (ADS)

Hybrid density functional theory has been used to study the stability and behavior of rare gases (He, Ne, Ar, Kr and Xe) in uranium dioxide. The calculations have been performed using the all-electron full-potential linearized augmented plane wave plus local orbitals basis (FP-L/APW+lo) method. Three insertion sites are considered: the octahedral interstitial position and the oxygen and uranium substitution sites. The defect formation energy, the optimized lattice constants and the volume variation induced by gaseous atom incorporation, and the electronic structure are studied for each rare gas in anti-ferromagnetic UO2 phase without and with spin-orbit coupling (scalar vs. "full" relativistic). The results indicate that the lattice constants and formation energies increase with the increase of the radius of the rare gases. The octahedral interstitial position is the most favorable occupation site. All incorporation energies are found to be positive implying an exothermic process.

Ma, Li; Ray, Asok

2011-03-01

48

Cytotoxic effect of uranium dioxide on rat alveolar macrophages  

Microsoft Academic Search

Alveolar macrophages obtained by bronchial lavage were used to assess the response of these cells to cultivation in media containing increasing concentrations of particulate UO. The characteristic time course of uranium effects on alveolar macrophages was determined by analyzing cell viability and incorporation of uranium particles. This study reveals the ability of alveolar macrophages to phagocytize uranium particles despite the

D. R. Tasat; B. Derey

1987-01-01

49

Molecular dynamics simulation of the melting of uranium dioxide nanocrystals  

NASA Astrophysics Data System (ADS)

The melting of vacuum-isolated uranium dioxide (UO2) nanocrystals is studied by molecular dynamics simulation using the approximation of pair potentials and point ions. The size dependences of the melting temperature, the heat of melting, and the density jump of cubic crystals up to 1000 nm3 in size are measured for the ten most relevant sets of pair potentials. The linear and parabolic extrapolations of these dependences to macroscopic sizes are considered, and the parabolic extrapolation is found to be better for analyzing data on the melting temperature and heat.

Boyarchenkov, A. S.; Potashnikov, S. I.; Nekrasov, K. A.; Kupryazhkin, A. Ya.

2012-08-01

50

DECONTAMINATION OF URANIUM  

DOEpatents

This patent deals with the separation of rare earth and other fission products from neutron bombarded uranium. This is accomplished by melting the uranium in contact with either thorium oxide, maguesium oxide, alumnum oxide, beryllium oxide, or uranium dioxide. The melting is preferably carried out at from 1150 deg to 1400 deg C in an inert atmosphere, such as argon or helium. During this treatment a scale of uranium dioxide forms on the uranium whtch contains most of the fission products.

Feder, H.M.; Chellew, N.R.

1958-02-01

51

New approaches in the characterization of uranium dioxide  

SciTech Connect

Uranium dioxide has been characterized for several years by the well-known BET, Fisher, and other methods. However, it has now been possible to draw new conclusions by combining the common characteristics to arrive at new characteristics. For example, in the preparation of the powder precursor ammonium diuranate (ADU), the increase in particle size with increase in precipitation temperature (as shown by sieve analysis) could be either due to crystal growth or clustering of smaller crystals. A corresponding increase in specific surface area (SSA) and the decrease in tap density would indicate clustering while the opposite would indicate crystal growth. The product of the SSA and the average particle size (APS) characterizes the compactability of the uranium dioxide powder while the ratio characterizes its sinterability. In addition, new characterization methods have also been evolved. Compaction maps have been drawn to characterize the compaction process in relation to pressing defects, such as cracks, end caps, and low density. The coarsening-densification transition temperature (CDTT) has been suggested to characterize the sintering process in relation to pretreatment.

Narasimha Murty, B.; Balakrishna, Palanki; Yadav, R.B.; Ganguly, C

2002-09-15

52

Production of sized particles of uranium oxides and uranium oxyfluorides  

Microsoft Academic Search

A process is claimed for converting uranium hexafluoride (UF) to uranium dioxide (UO) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride

I. E Knudsen; C. C. Randall

1976-01-01

53

Dissolution of sludges containing uranium dioxide and metallic uranium in nitric acid  

SciTech Connect

The dissolution in nitric acid of sludges containing uranium oxide and uranium has been modeled. That study has shown that it was necessary to continuously feed the dissolver to have an appropriate control of the reaction. If a unique procedure is deemed preferable, NH03 6M has been used.

Flament, T.A.

1998-08-25

54

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

55

Mathematical modelling of uranium dioxide conversion in a moving bed furnace  

Microsoft Academic Search

We present a mathematical model for simulating the steady-state behaviour of a moving bed furnace used in the French nuclear fuel making route. This furnace is a counterflow gassolid reactor which converts uranium trioxide UO3 into uranium dioxide UO2, then into uranium tetrafluoride UF4. The model describes most of the physico-chemical phenomena occurring into the reactor by coupling a mechanistic

B Dussoubs; J Jourde; F Patisson; J. L Houzelot; D Ablitzer

2002-01-01

56

Strain fields and line energies of dislocations in uranium dioxide  

NASA Astrophysics Data System (ADS)

Computer simulations are used to investigate the stability of typical dislocations in uranium dioxide. We explain in detail the methods used to produce the dislocation configurations and calculate the line energy and Peierls barrier for pure edge and screw dislocations with the shortest Burgers vector {1\\over 2} \\langle 110 \\rangle . The easiest slip system is found to be the {100}lang110rang system for stoichiometric UO2, in agreement with experimental observations. We also examine the different strain fields associated with these line defects and the close agreement between the strain field predicted by atomic scale models and the application of elastic theory. Molecular dynamics simulations are used to investigate the processes of slip that may occur for the three different edge dislocation geometries and nudged elastic band calculations are used to establish a value for the Peierls barrier, showing the possible utility of the method in investigating both thermodynamic average behaviour and dynamic processes such as creep and plastic deformation.

Parfitt, David C.; Bishop, Clare L.; Wenman, Mark R.; Grimes, Robin W.

2010-05-01

57

Strain fields and line energies of dislocations in uranium dioxide.  

PubMed

Computer simulations are used to investigate the stability of typical dislocations in uranium dioxide. We explain in detail the methods used to produce the dislocation configurations and calculate the line energy and Peierls barrier for pure edge and screw dislocations with the shortest Burgers vector ?110?. The easiest slip system is found to be the {100}?110? system for stoichiometric UO(2), in agreement with experimental observations. We also examine the different strain fields associated with these line defects and the close agreement between the strain field predicted by atomic scale models and the application of elastic theory. Molecular dynamics simulations are used to investigate the processes of slip that may occur for the three different edge dislocation geometries and nudged elastic band calculations are used to establish a value for the Peierls barrier, showing the possible utility of the method in investigating both thermodynamic average behaviour and dynamic processes such as creep and plastic deformation. PMID:21393662

Parfitt, David C; Bishop, Clare L; Wenman, Mark R; Grimes, Robin W

2010-04-07

58

Habit planes for U4O9 precipitation in uranium dioxide  

Microsoft Academic Search

A metallographic examination of fused uranium oxide revealed the ; presence of a second phase which had precipitated in a Widmanstatten structure ; along four well defined planes in the matrix. An x-ray powder pattern showed ; that the matrix was UO and the second phase was UO same ; structure was also observed in a sintered uranium dioxide pellet

R. H. Tuxworth; W. Evans

1959-01-01

59

A thermogravimetric study of the kinetics of hydrofluorination of uranium dioxide  

Microsoft Academic Search

The kinetics of the transformation of uranium dioxide to uranium tetrafluoride by hydrofluorination have been studied with the aid of thermogravimetric experiments performed at temperatures from 220 to 450C in a nitrogen-diluted hydrogen fluoride atmosphere. Using the Grainy Pellet Model coupled with an optimization program, the rate controlling mechanisms and the characteristic kinetic parameters were determined. The reaction was found

Ch. Nicole; F. Patisson; D. Ablitzer; J.-L. Houzelot

1996-01-01

60

Determination of Laser-Evaporated Uranium Dioxide by Neutron Activation Analysis.  

National Technical Information Service (NTIS)

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...

R. Allred

1987-01-01

61

Pressure Bonding Ability of Uranium Dioxide Powders in Relation to the Evolution of Their Surface Properties.  

National Technical Information Service (NTIS)

The long term storage of sinterable uranium dioxide powders generally improves their pressure bonding ability and the strength of the resulting green pellets. Evidence of the gradual evolution of the surface texture and composition of these powders during...

J. Danroc

1982-01-01

62

Influence of zirconium and niobium on cathodic deposition of uranium dioxide from alkali chloride melts  

SciTech Connect

Electrocrystallization of uranium dioxide from molten chloride electrolytes in the presence of zirconium(IV) and niobium(V) was studied by voltammetry. Zirconium(IV) was found to react with uranium dioxide according to exchange mechanism to form (1 - x)UO{sub 2}{center_dot}xZrO{sub 2} solid solutions. Niobium(IV), a product of cathodic reduction of niobium(V), enters into the exchange reaction with uranium dioxide to yield (1 - y)UO{sub 2{center_dot}y}NbO{sub 2} solid solutions. In the case of simultaneous presence of Nb(V) and Zr(IV) in electrolyte, ternary (1 - x - y)UO{sub 2 {center_dot}x}ZrO{sub 2{center_dot}y}NbO{sub 2} solid solutions are obtained at the cathode surface. Nucleation of the solid solutions phase was shown to occurs at the most active sites of the crystalline precipitate of uranium dioxide.

Komarov, V.E.; Borodina, N.P.; Martem`yanova, Z.S. [Institute of High-Temperature Electrochemistry, Ekaterinburg (Russian Federation)

1995-07-01

63

PROCESS FOR PRODUCING URANIUM HEXAFLUORIDE  

Microsoft Academic Search

A process for the production of uranium hexafluoride from the oxides of ; uranium is reported. In accordance with the method the higher oxides of uranium ; may be reduced to uranium dioxide (UO), the latter converted into uranium ; tetrafluoride by reaction with hydrogen fluoride, and the UF convented to ; UF by reaction with a fluorinating agent. The

1957-01-01

64

Costs for Manufacturing Thorium-Uranium Dioxide Fuels for Light Water Reactors  

SciTech Connect

The results of a 2-yr effort to determine the capability of U.S. fuel manufacturers to economically manufacture thorium-uranium dioxide (ThO{sub 2}-UO{sub 2}) fuel in plants that have previously only manufactured UO{sub 2} fuel with <5% {sup 235}U enrichment are presented. It was determined that there were no fundamental obstacles to converting the current plants that manufacture a uranium-oxide-only fuel to a mixed thorium-uranium dioxide fuel. However, the differential costs for manufacturing a 75% ThO{sub 2}-25% UO{sub 2} fuel, with the uranium enriched with 20% {sup 235}U, as compared to a 100% UO{sub 2} fuel, was between $269 and $291/kg of metal oxide fuel, depending on the manufacturing method used to convert the uranium and thorium feeds to the dioxide powders. More than 90% of this cost was associated with the increased cost of the uranium feed and the addition of the thorium feed. If a 70% ThO{sub 2}-30% UO{sub 2} fuel were used, the differential costs would increase to between $519 and $542/kg of metal oxide fuel, of which >95% is associated with the uranium and thorium feed materials.

Lahoda, Edward J. [Westinghouse Electric Corporation (United States)

2004-07-15

65

Green strength of zirconium sponge and uranium dioxide powder compacts  

SciTech Connect

Zirconium metal sponge is compacted into rectangular or cylindrical shapes using hydraulic presses. These shapes are stacked and electron beam welded to form a long electrode suitable for vacuum arc melting and casting into solid ingots. The compact electrodes should be sufficiently strong to prevent breakage in handling as well as during vacuum arc melting. Usually, the welds are strong and the electrode strength is limited by the green strength of the compacts, which constitute the electrode. Green strength is also required in uranium dioxide (UO{sub 2}) powder compacts, to withstand stresses during de-tensioning after compaction as well as during ejection from the die and for subsequent handling by man and machine. The strengths of zirconium sponge and UO{sub 2} powder compacts have been determined by bending and crushing respectively, and Weibul moduli evaluated. The green density of coarse sponge compact was found to be larger than that from finer sponge. The green density of compacts from lightly attrited UO{sub 2} powder was higher than that from unattrited category, accompanied by an improvement in UO{sub 2} green crushing strength. The factors governing green strength have been examined in the light of published literature and experimental evidence. The methodology and results provide a basis for quality control in metal sponge and ceramic powder compaction in the manufacture of nuclear fuel.

Balakrishna, Palanki [Nuclear Fuel Complex, Hyderabad 500 062 (India)], E-mail: bpalanki@rediffmail.com; Murty, B. Narasimha; Sahoo, P.K.; Gopalakrishna, T. [Nuclear Fuel Complex, Hyderabad 500 062 (India)

2008-07-15

66

Neptunium interaction with uranium dioxide in aqueous solution  

NASA Astrophysics Data System (ADS)

Neptunium, Np(V) and Np(IV), sorption onto uranium dioxide surface was studied at various values of pH. Sorption was studied in two sets of experiments with different redox conditions that correspond to either Np(V) (Set 1) or Np(IV) (Set 2) in solution. In Set 1 the reduction of Np(V) was established when low pH solution covered a UO2 surface. When the pH increased, the sorption of neptunium is decreased. At pH > 5.5 neptunium sequestration from solution is governed by Np(V) sorption onto UO2.25. In Set 2 (the more anoxic conditions) complete neptunium sorption is established at pH > 2: it is present in the tetravalent form over the whole pH range. The proposed mechanisms of neptunium sorption was suggested by using pH sorption edges of Th(IV) as an analog to Np(IV) onto UO2 and Np(V) onto ThO2. The UO2 surface was characterized by X-ray photoelectron spectroscopy (XPS) after equilibration with aqueous solutions at different pH values.

Batuk, O. N.; Kalmykov, St. N.; Petrov, V. G.; Zakharova, E. V.; Teterin, Yu. A.; Teterin, A. Yu.; Shapovalov, V. I.; Haire, M. J.

2007-05-01

67

A study of helium mobility in polycrystalline uranium dioxide  

NASA Astrophysics Data System (ADS)

The mobility of Helium in polycrystalline uranium dioxide was studied by implanting samples with 3He ions at depths of approximately 1 ?m and at concentrations in the region of 0.1 at.%. Samples were subsequently annealed at temperatures ranging between 700 C and 1100 C. Helium movement was then characterised using three different types of Nuclear Reaction Analysis (NRA) techniques based on the 3He(d,?)p reaction. The fraction of helium released from samples was measured during annealing at high temperature as a function of time. After each annealing sequence, helium depth profiles were obtained for each sample. In some cases, samples were characterised over small areas (60 60 ?m2), using a micrometre size deuteron beam. This enables the measurement of helium distributions at the surface of samples. Using this novel approach which provides time and space dependent information relating to helium atom location, we show that grain boundaries act as effective short circuits for helium movement and release at all temperatures. Also, at temperatures above approximately 800 C, in areas around the grain boundaries extending into the grain over distances of the order of microns, helium diffusion is high. In areas further into the grain, diffusion proceeds much more slowly presumably as a result of helium cluster formation. These observations are interpreted based on radiation damage production and annealing processes.

Garcia, P.; Martin, G.; Desgardin, P.; Carlot, G.; Sauvage, T.; Sabathier, C.; Castellier, E.; Khodja, H.; Barthe, M.-F.

2012-11-01

68

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

69

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

70

Production of uranium dioxide. [Patent 3; stage fluidized bed reaction of UF with H and steam  

Microsoft Academic Search

A three stage fluidized bed process is described for converting uranium hexafluoride (UF) to a ceramic-grade uranium dioxide (UO) powder by first, reacting hydrogen and steam with UF in a first fluidized bed in a temperature range of from about 475 to 600°C to form solid intermediate products UOF and UO; second, reacting hydrogen and steam with the intermediate products

Knudsen

1977-01-01

71

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

72

Irradiation damage effects on helium migration in sintered uranium dioxide  

NASA Astrophysics Data System (ADS)

In this study, the effects of radiation on helium migration are investigated through the analysis of polycrystalline uranium dioxide samples irradiated at fluences up to 5 1015 at. cm-2 with 8 MeV iodine ions. Following irradiation, samples are implanted with 500 keV 3He+ ions at fluences in the range of 1016 at. cm-2. Three nuclear reaction analysis (NRA) techniques are subsequently implemented using the 3He(2H,1H)4He reaction. The influence of temperature using NRA was first studied based upon 3He depth profile changes and the on-line monitoring of helium release. The effect of the sample microstructure was also investigated at the grain scale by performing analyses of the helium spatial distribution with a nuclear microprobe. Neither substantial helium release nor depth profile changes are observed at temperatures below 900 C in irradiated samples. Following annealing at temperatures above 1000 C, a substantial proportion of the implanted helium is released from the samples. From this temperature upwards, the two dimensional He cartographies reveal that the gas has been preferentially released in the vicinity of grain boundaries. These results can be interpreted in the light of previous studies in terms of gas precipitation and re-solution. Helium precipitation is enhanced in irradiated samples up to 900 C because of the presence of irradiation induced defects. At temperatures in excess of 1000 C, the precipitated helium is partly returned to the matrix hence it is preferentially released in regions adjacent to grain boundaries, which appear to act as defect sinks.

Martin, G.; Sabathier, C.; Carlot, G.; Desgardin, P.; Raepsaet, C.; Sauvage, T.; Khodja, H.; Garcia, P.

2012-02-01

73

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

74

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

75

DEPLETED URANIUM DIOXIDE AS SNF WASTE PACKAGE FILL: A DISPOSAL OPTION  

Microsoft Academic Search

The use of depleted uranium (DU) dioxide (DUO ) particles is being investigated for use in 2 repository waste packages (WPs) containing light-water reactor spent nuclear fuel (SNF). The DUO may be incorporated into the WP (1) as a particulate fill of all void spaces including the 2 SNF coolant channels and (2) as a component of the WP structure.

Charles W. Forsberg

76

Relationship between dissolution rate of uranium dioxide pellets in nitric acid solutions and their porosity  

Microsoft Academic Search

Dissolution of uranium dioxide pellets \\/10 mm11 mm\\/ in nitric acid was studied. A dependence of the initial dissolution rate on acid concentration and temperature was observed. The effective surface area of the pellet was measured during the dissolution process, and compared with its apparent surface area. The experimental dissolution curve was in good agreement with the curve obtained by

T. Fukasawa; Y. Ozawa

1986-01-01

77

Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations  

Microsoft Academic Search

The stability range of intrinsic point defects in uranium dioxide is determined as a function of temperature, oxygen partial pressure, and non-stoichiometry. The computational approach integrates high accuracy ab initio electronic-structure calculations and thermodynamic analysis supported by experimental data. In particular, the density functional theory calculations are performed at the level of the spin polarized, generalized gradient approximation and includes

Pankaj Nerikar; Taku Watanabe; James S. Tulenko; Simon R. Phillpot; Susan B. Sinnott

2009-01-01

78

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

Microsoft Academic Search

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

J. S. Herring; P. E. MacDonald

1999-01-01

79

Virus-mediated FCC iron nanoparticle induced synthesis of uranium dioxide nanocrystals.  

PubMed

A reducing system involving M13 virus-mediated FCC Fe nanoparticles was employed to achieve uranium reduction and synthesize uranium dioxide nanocrystals. Here we show that metastable face-centered cubic (FCC) Fe nanoparticles were fabricated around the surface of the M13 virus during the specific adsorption of the virus towards Fe ions under a reduced environment. The FCC phase of these Fe nanoparticles was confirmed by careful TEM characterization. Moreover, this virus-mediated FCC Fe nanoparticle system successfully reduced contaminable U(VI) into UO(2) crystals with diameters of 2-5nm by a green and convenient route. PMID:21730559

Ling, Tao; Yu, Huimin; Shen, Zhongyao; Wang, Hui; Zhu, Jing

2008-02-18

80

Incidence of High Nitrogen in Sintered Uranium Dioxide: A Case Study  

SciTech Connect

Nitrogen content, above the specified limit of 75 {mu}g(gU){sup -1}, was encountered in sintered uranium dioxide in the course of its manufacture. The cause was traced to the sintering process, wherein carbon, a degradation product of the die wall or admixed lubricant, was retained in the compact as a result of inadvertent reversal of gas flow in the sintering furnace. In the presence of carbon, the uranium dioxide reacted with nitrogen from the furnace atmosphere to form nitride. The compacts with high nitrogen were also those with low sintered density, arising from low green density. The low green density was due to filling problems of an inhomogeneous powder. The experiments carried out establish the causes of high nitrogen to be the carbon residue from lubricant when the UO{sub 2} is sintered in a cracked ammonia atmosphere.

Balakrishna, Palanki; Murty, B. Narasimha; Anuradha, M.; Yadav, R.B.; Jayaraj, R.N

2005-05-15

81

AN INTEGRATED ONCE-THROUGH FUEL CYCLE WITH DEPLETED-URANIUM-DIOXIDE SNF MULTIFUNCTION CASKS  

Microsoft Academic Search

An advanced once-through nuclear fuel cycle is proposed that integrates (1) front- and back-end fuel cycle operations and (2) management of all long-lived radionuclides. The front-end of the fuel cycle remains unchanged except that the depleted uranium (DU) from the enrichment facilities (in the form of DU dioxideDUO2) is used to produce multifunction shielded casks. Several years after discharge, spent

Charles W. Forsberg; Les R. Dole

82

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

Microsoft Academic Search

Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric uranium-plutonium dioxide condensed phase (U\\/sub 1-y\\/Pu\\/sub y\\/)O\\/sub 2-x\\/, as functions of T, x, and y, have been calculated for 0.0 less than or equal to x less than or equal to 0.1, 0.0 less than or equal to y less than or equal to 0.3, and for the temperature range

D. W. Green; J. K. Fink; L. Leibowitz

1982-01-01

83

The oxidative dissolution mechanism of uranium dioxide. I. The effect of temperature in hydrogen carbonate medium  

Microsoft Academic Search

The oxidative dissolution of uranium (IV) dioxide has been experimentally investigated as a function of hydrogen carbonate concentration at 4 different temperatures (10, 25, 45, and 60C) by using a continuous thin-layer flow-through reactor. The experimental results have been interpreted as evidence for a bicarbonate-promoted oxidative dissolution mechanism which can be differentiated in to 3 steps: 1) initial oxidation of

Joan de Pablo; Ignasi Casas; Javier Gimnez; Mireia Molera; Miquel Rovira; Lara Duro; Jordi Bruno

1999-01-01

84

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

85

URANIUM COMPOSITIONS  

DOEpatents

This patent relates to high purity uranium alloys characterized by improved stability to thermal cycling and low thermal neutron absorption. The high purity uranium alloy contains less than 0.1 per cent by weight in total amount of any ore or more of the elements such as aluminum, silicon, phosphorous, tin, lead, bismuth, niobium, and zinc.

Allen, N.P.; Grogan, J.D.

1959-05-12

86

URANIUM EXTRACTION  

Microsoft Academic Search

The recovery of uranium values from uranium ore such as pitchblende is ; described. The ore is first dissolved in nitric acid, and a water soluble ; nitrate is added as a salting out agent. The resulting feed solution is then ; contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a ; portion of the impurities

C. D. Harrington; J. V. Opie

1958-01-01

87

Uranium enrichment  

SciTech Connect

GAO was asked to address several questions concerning a number of proposed uranium enrichment bills introduced during the 100th Congress. The bill would have restructured the Department of Energy's uranium enrichment program as a government corporation to allow it to compete more effectively in the domestic and international markets. Some of GAO's findings discussed are: uranium market experts believe and existing market models show that the proposed DOE purchase of a $750 million of uranium from domestic producers may not significantly increase production because of large producer-held inventories; excess uranium enrichment production capacity exists throughout the world; therefore, foreign producers are expected to compete heavily in the United States throughout the 1990s as utilities' contracts with DOE expire; and according to a 1988 agreement between DOE's Offices of Nuclear Energy and Defense Programs, enrichment decommissioning costs, estimated to total $3.6 billion for planning purposes, will be shared by the commercial enrichment program and the government.

Not Available

1989-01-01

88

The oxidative dissolution mechanism of uranium dioxide. I. The effect of temperature in hydrogen carbonate medium  

NASA Astrophysics Data System (ADS)

The oxidative dissolution of uranium (IV) dioxide has been experimentally investigated as a function of hydrogen carbonate concentration at 4 different temperatures (10, 25, 45, and 60C) by using a continuous thin-layer flow-through reactor. The experimental results have been interpreted as evidence for a bicarbonate-promoted oxidative dissolution mechanism which can be differentiated in to 3 steps: 1) initial oxidation of the uranium dioxide solid surface; 2) binding of HCO 3- at the U(VI) sites of the oxidized layer; and 3) detachment of the U(VI)-carbonato surface complex. From this mechanism a general rate equation has been derived: r= k 1k 2{ >UO2} tot[ O2][HCO3-] /k -1+k 2[ HCO3-]+k 1[ O2] Which allows to rationalization of some of the discrepancies found in the literature concerning the dependence of the dissolution rate of uranium dioxide on the hydrogen carbonate concentration. The application of this bicarbonate-promoted oxidative dissolution mechanism allows us to predict unirradiated UO 2 and spent nuclear fuel dissolution rates which are in satisfactory agreement with rates determined experimentally. Some differences observed in spent fuel dissolution rates have been attributed to radiolysis effects.

de Pablo, Joan; Casas, Ignasi; Gimnez, Javier; Molera, Mireia; Rovira, Miquel; Duro, Lara; Bruno, Jordi

89

The oxidative dissolution mechanism of uranium dioxide. 1: The effect of temperature in hydrogen carbonate medium  

SciTech Connect

The oxidative dissolution of uranium (IV) dioxide has been experimentally investigated as a function of hydrogen carbonate concentration at 4 different temperatures (10, 25, 45, and 60 C) by using a continuous thin-layer flow-through reactor. The experimental results have been interpreted as evidence for a bicarbonate-promoted oxidative dissolution mechanism which can be differentiated in to 3 steps: (1) initial oxidation of the uranium dioxide solid surface; (2) binding of HCO{sub 3}{sup {minus}} at the U(VI) sites of the oxidized layer; and (3) detachment of the U(VI)-carbonato surface complex. From this mechanism a general rate equation has been derived, which allows rationalization of some of the discrepancies found in the literature concerning the dependence of the dissolution rate of uranium dioxide on the hydrogen carbonate concentration. The application of this bicarbonate-promoted oxidative dissolution mechanism allows us to predict unirradiated UO{sub 2} and spent nuclear fuel dissolution rates which are in satisfactory agreement with rates determined experimentally. Some differences observed in spent fuel dissolution rates have been attributed to radiolysis effects.

De Pablo, J.; Casas, I.; Gimenez, J.; Molera, M.; Rovira, M.; Duro, L.; Bruno, J.

1999-10-01

90

Study of 5f electron states in Uranium Dioxide using Inelastic Neutron Spectroscopy  

NASA Astrophysics Data System (ADS)

Uranium dioxide, a nuclear fuel material is one of the commonly studied actinide compounds and the nature of their 5f electrons, their degree of localization and their high-temperature thermodynamic properties have been studied in detail. Knowledge of the crystal field potential is an important part of these studies. High-resolution, high-energy transfer inelastic neutron scattering has been used to study the crystal field excitations in Uranium Dioxide. These measurements were made on PHAROS at the Los Alamos Neutron Science Center, Los Alamos National Laboratory. Since all the dipole allowed transitions in the free ion ground manifold are known, the experiments allow a complete determination of the crystal field potential and 5f-electron eigenstates in Uranium Dioxide. The ground state is accurately given by intermediate-coupling approximation with little changes by J-mixing effects. Below the Neel temperature of 30.8 K, a splitting of the cubic crystal field levels is observed. The splittings are shown to be consistent with the triple-k model.

Rajaram, Ramya; Kern, Sanford; Lander, Gerry; McQueeney, Rob; Nakotte, Heinz

2003-03-01

91

PRODUCTION OF URANIUM METAL BY CARBON REDUCTION  

DOEpatents

The preparation of uranium metal by the carbon reduction of an oxide of uranium is described. In a preferred embodiment of the invention a charge composed of carbon and uranium oxide is heated to a solid mass after which it is further heated under vacuum to a temperature of about 2000 deg C to produce a fused uranium metal. Slowly ccoling the fused mass produces a dendritic structure of uranium carbide in uranium metal. Reacting the solidified charge with deionized water hydrolyzes the uranium carbide to finely divide uranium dioxide which can be separated from the coarser uranium metal by ordinary filtration methods.

Holden, R.B.; Powers, R.M.; Blaber, O.J.

1959-09-22

92

First-principles study on oxidation effects in uranium oxides and high-pressure high-temperature behavior of point defects in uranium dioxide  

NASA Astrophysics Data System (ADS)

Formation Gibbs free energy of point defects and oxygen clusters in uranium dioxide at high-pressure high-temperature conditions are calculated from first principles, using the LSDA+U approach for the electronic structure and the Debye model for the lattice vibrations. The phonon contribution on Frenkel pairs is found to be notable, whereas it is negligible for the Schottky defect. Hydrostatic compression changes the formation energies drastically, making defect concentrations depend more sensitively on pressure. Calculations show that, if no oxygen clusters are considered, uranium vacancy becomes predominant in overstoichiometric UO2 with the aid of the contribution from lattice vibrations, while compression favors oxygen defects and suppresses uranium vacancy greatly. At ambient pressure, however, the experimental observation of predominant oxygen defects in this regime can be reproduced only in a form of cuboctahedral clusters, underlining the importance of defect clustering in UO2+x. Making use of the point defect model, an equation of state for nonstoichiometric oxides is established, which is then applied to describe the shock Hugoniot of UO2+x. Furthermore, the oxidization and compression behavior of uranium monoxide, triuranium octoxide, uranium trioxide, and a series of defective UO2 at 0 K are investigated. The evolution of mechanical properties and electronic structures with an increase of the oxidation degree are analyzed, revealing the transition of the ground state of uranium oxides from metallic to Mott insulator and then to charge-transfer insulator due to the interplay of strongly correlated effects of 5f orbitals and the shift of electrons from uranium to oxygen atoms.

Geng, Hua Y.; Song, Hong X.; Jin, K.; Xiang, S. K.; Wu, Q.

2011-11-01

93

PROCESS OF PRODUCING REFRACTORY URANIUM OXIDE ARTICLES  

DOEpatents

A method is presented for fabricating uranium oxide into a shaped refractory article by introducing a uranium halide fluxing reagent into the uranium oxide, and then mixing and compressing the materials into a shaped composite mass. The shaped mass of uranium oxide and uranium halide is then fired at an elevated temperature so as to form a refractory sintered article. It was found in the present invention that the introduction of a uraninm halide fluxing agent afforded a fluxing action with the uranium oxide particles and that excellent cohesion between these oxide particles was obtained. Approximately 90% of uranium dioxide and 10% of uranium tetrafluoride represent a preferred composition.

Hamilton, N.E.

1957-12-01

94

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

95

Machining of uranium and uranium alloys  

SciTech Connect

Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures.

Morris, T.O.

1981-12-14

96

URANIUM ALLOYS  

DOEpatents

Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

Seybolt, A.U.

1958-04-15

97

Uranium industry annual 1996  

SciTech Connect

The Uranium Industry Annual 1996 (UIA 1996) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1996 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. Data on uranium raw materials activities for 1987 through 1996 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2006, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. A feature article, The Role of Thorium in Nuclear Energy, is included. 24 figs., 56 tabs.

NONE

1997-04-01

98

Cask Size and Weight Reduction Through the Use of Depleted Uranium Dioxide DUO2)Steel Cermet Material  

Microsoft Academic Search

Newly developed depleted uranium (DU) composite materials enable fabrication of spent nuclear fuel (SNF) transport and storage casks that are smaller and lighter in weight than casks made with conventional materials. One such material is DU dioxide (DUO2)-steel cermet. This work examines the radiation shielding efficiency of this new cermet material as compared with conventional steel used in Holtec International's

M. Jonathan Haire; Paul M. Swaney

99

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

100

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

101

Effect of the cascade energy on defect production in uranium dioxide  

NASA Astrophysics Data System (ADS)

The primary damage induced by a displacement cascade in a pure uranium dioxide matrix was investigated using classical molecular dynamics simulations. Cascades were initiated by accelerating a uranium primary knock-on atom (PKA) to a kinetic energy ranging from 1 keV to 80 keV inside a perfect UO2 lattice at low temperature (300 K and 700 K). There is little effect of temperature in the temperature range studied. Following the cascade event, the damage level, defined as the total number of defects irrespective of whether they form clusters or not, is proportional to the initial kinetic energy of the PKA, in agreement with the literature relating to other materials. The linear dependence of damage upon initial PKA energy results from the formation of subcascades at high energy and constitutes a simple law which can be applied to any material and used in order to extrapolate molecular dynamics results to high energy PKAs. The nature of irradiation induced defects has also been studied as a function of the cascade energy.

Martin, G.; Garcia, P.; van Brutzel, L.; Dorado, B.; Maillard, S.

2011-07-01

102

PREPARATION OF URANIUM MONOSULFIDE  

DOEpatents

A process is given for preparing uranium monosulfide from uranium tetrafluoride dissolved in molten alkali metal chloride. A hydrogen-hydrogen sulfide gas mixture passed through the solution precipitates uranium monosulfide. (AEC)

Yoshioka, K.

1964-01-28

103

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

SciTech Connect

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 uranium in moist air suggests that similar catalytic processes participate in the mechanism of moisture-enhanced corrosion of uranium and plutonium. Evaluation of chemical and kinetic data for corrosion of the metals leads to a comprehensive mechanism for corrosion in dry air, water vapor, and moist air. Results are applied in confirming that the corrosion rate of Pu in water vapor decreases sharply between 100 and 200 degrees C.

Haschke, John M.; Allen, Thomas H.; Morales, Luis A.

1999-06-18

104

First-principles calculation and experimental study of oxygen diffusion in uranium dioxide  

NASA Astrophysics Data System (ADS)

This work provides an illustration that density functional theory (DFT) + U calculations may quantitatively describe transport phenomena in uranium dioxide. Oxygen diffusion mechanisms are investigated using both ab initio calculations and experimental approaches mainly involving self-diffusion coefficient measurements. The dependences of the experimental data upon oxygen potential and sample impurity content demonstrate, by comparison with basic point defect and diffusion theory, that oxygen migration occurs via an interstitial mechanism. The temperature study provides an estimate of interstitial formation and migration energies which compare very favorably to energies calculated using the DFT+U approximation relating to the interstitialcy mechanism. Also, vacancy migration and Frenkel pair formation energies are shown to agree well with existing data.

Dorado, Boris; Garcia, Philippe; Carlot, Galle; Davoisne, Carine; Fraczkiewicz, Mathieu; Pasquet, Bertrand; Freyss, Michel; Valot, Carole; Baldinozzi, Guido; Simone, David; Bertolus, Marjorie

2011-01-01

105

Multipolar, magnetic, and vibrational lattice dynamics in the low-temperature phase of uranium dioxide  

NASA Astrophysics Data System (ADS)

We report the results of inelastic neutron scattering experiments performed with triple-axis spectrometers to investigate the low-temperature collective dynamics in the ordered phase of uranium dioxide. The results are in very good agreement with the predictions of mean-field random phase approximation calculations, emphasizing the importance of multipolar superexchange interactions. By comparing neutron scattering intensities in different polarization channels and at equivalent points in different Brillouin zones, we show the mixed magnetovibrational-quadrupolar character of the observed excitations. The high-energy resolution afforded by the cold triple-axis spectrometer allowed us to study in detail the magnon-phonon interaction giving rise to avoided crossings along the [00?] reciprocal space direction.

Caciuffo, R.; Santini, P.; Carretta, S.; Amoretti, G.; Hiess, A.; Magnani, N.; Regnault, L.-P.; Lander, G. H.

2011-09-01

106

Swelling due to fission products and additives dissolved within the uranium dioxide lattice  

NASA Astrophysics Data System (ADS)

Simulations using empirical inter-atomic potentials have been used to predict the change in volume of the uranium dioxide lattice due to the accommodation of soluble fuel additives and fission products. The incorporation of divalent, trivalent and tetravalent cations are considered. The change in accommodation mechanism for aliovalent cations between UO2 and UO2+x gives rise to markedly different defect volumes. Experimental data is in good agreement with the predictions made in this work, particularly swelling as a function of dopant concentration under different conditions. The predicted defect volumes have been combined to predict the change in lattice volume with burnup (fission product inventory) due to incorporation of these soluble species, which agrees well with swelling data from irradiated fuel.

Middleburgh, S. C.; Grimes, R. W.; Desai, K. H.; Blair, P. R.; Hallstadius, L.; Backman, K.; Van Uffelen, P.

2012-08-01

107

PREPARATION OF URANIUM TRIOXIDE  

DOEpatents

The production of uranium trioxide from aqueous solutions of uranyl nitrate is discussed. The uranium trioxide is produced by adding sulfur or a sulfur-containing compound, such as thiourea, sulfamic acid, sulfuric acid, and ammonium sulfate, to the uranyl solution in an amount of about 0.5% by weight of the uranyl nitrate hexahydrate, evaporating the solution to dryness, and calcining the dry residue. The trioxide obtained by this method furnished a dioxide with a considerably higher reactivity with hydrogen fluoride than a trioxide prepared without the sulfur additive.

Buckingham, J.S.

1959-09-01

108

Uranium industry annual, 1986  

SciTech Connect

Uranium industry data collected in the EIA-858 survey provide a comprehensive statistical characterization of annual activities of the industry and include some information about industry plans over the next several years. This report consists of two major sections. The first addresses uranium raw materials activities and covers the following topics: exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment. The second major section is concerned with the following uranium marketing activities: uranium purchase commitments, uranium prices, procurement arrangements, uranium imports and exports, enrichment services, inventories, secondary market activities utility market requirements and related topics.

Not Available

1987-10-09

109

Computational Investigation of the Formation of Hyperstoichiometric Uranium Dioxide (U02+X)  

SciTech Connect

The stability of spent nuclear fuel as a waste form depends upon the oxidation behavior of uranium dioxide (UO{sub 2}) under repository conditions. Because U{sup 6+} phases are more soluble than U{sup 4+} phases, understanding the formation of higher-oxidized UO{sub 2} phases is important. While a variety of diffraction and spectroscopic studies have been used to investigate the oxidation behavior of UO{sub 2} to U{sub 4}O{sub 9}, questions still remain as to the effect of interstitial oxygen on the oxidation state of uranium in hyperstoichiometric UO{sub 2}. In this study, computational techniques were used to investigate questions such as: Is the formation of U{sup 5+} or U{sup 6+} more energetically favorable upon the oxidation of UO{sub 2}? And, how do calculated activation energies for the diffusion of interstitial oxygen in UO{sub 2} compare with experimental values? A density functional theory (DFT) approach was used to investigate the structural location of interstitial oxygen, the energy associated with oxygen substitution into different interstitial sites, and the influence of interstitial oxygen on the redox chemistry of uranium dioxide. Two different quantum mechanical programs were used to perform these calculations, one based on planewaves (CASTEP) and another that uses atomic-like basis. functions to describe the electronic structure of each atom (Dmol{sup 3}). Preliminary results from planewave calculations suggest that the formation of one U{sup 6+} is favorable to a more delocalized charge distribution resulting in the formation of two U{sup 5+} for every interstitial oxygen atom. Experimental studies suggest that two symmetrically unique locations exist for the incorporation of interstitial oxygen in bulk UO{sub 2}. Excess oxygen is thought to be incorporated along the perpendicular bisectors or the body diagonals of the unoccupied cubic sites created by lattice oxygen atoms in the UO{sub 2} structure. Using a single unit cell starting model, quantum mechanical calculations allow us to compare the relative energies associated with placing oxygen on these incorporation sites. Activation energies for the diffusion of oxygen from one such local energy minimum site to another are also evaluated. Calculations are expanded to larger defect cluster formations within the computational limits of DFT methods.

F.N. Somurskil; .R.C. Win; U.Ecke

2006-09-11

110

Monte Carlo Criticality Analysis of Simple Geometrics COntaining Tungsten Rhenium Alloys Engrained with Uranium Dioxide and Uranium Mononitride  

SciTech Connect

The critical mass and dimensions of simple geometries containing highly enriched uraniumdioxide (UO2) and uraniummononitride (UN) encapsulated in tungsten-rhenium alloys are determined using MCNP5 criticality calculations. Spheres as well as cylinders with length to radius ratios of 1.82 are computationally built to consist of 60 vol.% fuel and 40 vol.% metal matrix. Within the geometries the uranium is enriched to 93 wt.% uranium-235 and the rhenium content within the metal alloy was modeled over a range of 0 to 30 at.%. The spheres containing UO2 were determined to have a critical radius of 18.29 cm to 19.11 cm and a critical mass ranging from 366 kg to 424 kg. The cylinders containing UO2 were found to have a critical radius ranging from 17.07 cm to 17.844 cm with a corresponding critical mass of 406 kg to 471 kg. Spheres engrained with UN were determined to have a critical radius ranging from 14.82 cm to 15.19 cm and a critical mass between 222 kg and 242 kg. Cylinders which were engrained with UN were determined to have a critical radius ranging from 13.811 cm to 14.155 cm with a corresponding critical mass of 245 kg to 267 kg. The critical geometries were also computationally submerged in a neutronaically infinite medium of fresh water to determine the effects of rhenium addition on criticality accidents due to water submersion. The monte carlo analysis demonstrated that rhenium addition of up to 30 at.% can reduce the excess reactivity due to water submersion by up to $5.07 for UO2 fueled cylinders, $3.87 for UO2 fueled spheres and approximately $3.00 for UN fueled spheres and cylinders.

Jonathan A. Webb; Indrajit Charit

2011-08-01

111

Method for converting uranium oxides to uranium metal  

Microsoft Academic Search

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

Duerksen; Walter K

1988-01-01

112

URANIUM EXTRACTION  

DOEpatents

The recovery of uranium values from uranium ore such as pitchblende is described. The ore is first dissolved in nitric acid, and a water soluble nitrate is added as a salting out agent. The resulting feed solution is then contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a portion of the impurities are taken up by the ether. This acid ether extract is then separated from the aqueous raffinate, and contacted with water causing back extractioa of the uranyl nitrate and impurities into the water to form a crude liquor. After separation from the ether extract, this crude liquor is heated to about 118 deg C to obtain molten uranyl nitrate hexahydratc. After being slightly cooled the uranyl nitrate hexahydrate is contacted with acid free diethyl ether whereby the bulk of the uranyl nitrate is dissolved into the ethcr to form a neutral ether solution while most of the impurities remain in the aqueous waste. After separation from the aqueous waste, the resultant ether solution is washed with about l0% of its volume of water to free it of any dissolved impurities and is then contacted with at least one half its volume of water whereby the uranyl nitrate is extracted into the water to form an aqueous product solution.

Harrington, C.D.; Opie, J.V.

1958-07-01

113

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

114

PRODUCTION OF URANIUM MONOCARBIDE  

DOEpatents

A method of making essentially stoichiometric uranium monocarbide by pelletizing a mixture of uranium tetrafluoride, silicon, and carbon and reacting the mixture at a temperature of approximately 1500 to 1700 deg C until the reaction goes to completion, forming uranium monocarbide powder and volatile silicon tetrafluoride, is described. The powder is then melted to produce uranium monocarbide in massive form. (AEC)

Powers, R.M.

1962-07-24

115

PRODUCTION OF URANIUM TETRACHLORIDE  

DOEpatents

A process is descrlbed for the production of uranium tetrachloride by contacting uranlum values such as uranium hexafluoride, uranlum tetrafluoride, or uranium oxides with either aluminum chloride, boron chloride, or sodium alumlnum chloride under substantially anhydrous condltlons at such a temperature and pressure that the chlorldes are maintained in the molten form and until the uranium values are completely converted to uranlum tetrachloride.

Calkins, V.P.

1958-12-16

116

Ionic liquids for simultaneous preconcentration of some lanthanoids using dispersive liquid-liquid microextraction technique in uranium dioxide powder.  

PubMed

Ionic liquids in a dispersive liquid-liquid microextraction technique were used for determination of lanthanoids such as samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. In this process, an appropriate mixture of extraction solvent and disperser is rapidly injected into an aqueous sample containing samarium, europium, gadolinium, and dysprosium ions complexes with 1-hydroxy-2, 5-pyrrolidinedione, and consequently a cloudy solution is formed. It consists of fine droplets of extraction solventwhich are dispersed entirely into the aqueous phase. After centrifugation of this solution, the whole enriched phase was determined by inductively coupled plasma optical emission spectrometry. In the present work, the preconcentration factor, limit of detection, and relative standard deviation were investigated for samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. PMID:19368197

Mallah, Mohammad H; Shemirani, Farzaneh; Maragheh, Mohammad G

2009-03-15

117

Uranium industry annual 1985  

SciTech Connect

This report consists of two major sections. The first addresses uranium raw materials activities and covers the following topics: exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment. The second major section is concerned with the following uranium marketing activities: uranium purchase commitments, uranium prices, procurement arrangements, uranium imports and exports, enrichment services, inventories, secondary market activities, utility market requirements, and related topics. A glossary and appendices are included to assist the reader in interpreting the substantial array of statistical data in this report and to provide background information about the survey.

Not Available

1986-11-01

118

Determination of radium and uranium isotopes in natural waters by sorption on hydrous manganese dioxide followed by alpha-spectrometry  

Microsoft Academic Search

SummaryWater samples, spiked with 133Ba and 232U radiotracers, are scavenged for radium and uranium isotopes using hydrous manganese dioxide which is produced in-situ, by reacting manganese (+2) and permanganate ions at pH 8-9. The precipitate is solubilized with ascorbic and acetic acids and the resulting solution filtered through a glass fibre filter GF\\/F to remove particulate matter. The radium is

K. Burns; Z. Radecki

2005-01-01

119

Thermophysical Properties of Uranium Dioxide:. a Molecular Dynamics Study of Solid and Liquid Phases of Stoichiometric UO2  

NASA Astrophysics Data System (ADS)

Thermodynamic and transport properties of solid and liquid uranium dioxide were studied using classical molecular dynamics simulation, with a newly parametrized interionic model potential. In addition to the static and transport properties which have been previously reported by the authors, this study further confirms that temperature dependence of the calculated thermophysical properties of uranium dioxide are in agreement with the available experimental data at both solid and liquid phases in providing an alternative rigid ion potential to the other model potentials in literature. Although lattice parameter and density have been underestimated, overall results give a fairly good description of the UO2 system for wide range of temperature (0-4000 K). The transition to the superionic phase, Bredig transition, was successfully observed as a distinct ?-peak in specific heats at about 400 K below the experimental value. The results presented in our previous article and here show that the introduced alternative model potential for uranium dioxide is very promising and we are confident in the success of its use in future studies.

Gnay, S. D.; Kavanoz, H. B.; Akdere, .; Ta?seven, .

120

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

121

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

122

Ab initio construction of interatomic potentials for uranium dioxide across all interatomic distances  

SciTech Connect

We provide a methodology for generating interatomic potentials for use in classical molecular-dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. A rigorous method to objectively determine the shape of an interatomic potential over all length scales is introduced by building upon a charged-ion generalization of the well-known Ziegler-Biersack-Littmark universal potential that provides the short- and long-range limiting behavior of the potential. At intermediate ranges the potential is smoothly adjusted by fitting to ab initio data. Our formalism provides a complete description of the interatomic potentials that can be used at any energy scale, and thus, eliminates the inherent ambiguity of splining different potentials generated to study different kinds of atomic-materials behavior. We exemplify the method by developing rigid-ion potentials for uranium dioxide interactions under conditions ranging from thermodynamic equilibrium to very high atomic-energy collisions relevant for fission events.

Tiwary, P.; Walle, A. van de; Groenbech-Jensen, N. [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Department of Applied Science, University of California, Davis, California 95616 (United States)

2009-11-01

123

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

124

Computer simulation of structural modifications induced by highly energetic ions in uranium dioxide  

NASA Astrophysics Data System (ADS)

The structural modification caused by the high-energy-ion irradiation of single-crystalline uranium dioxide was simulated by the molecular dynamics method. As the initial condition, high kinetic energy was supplied to the individual atoms within a cylindrical region of nanometer-order radius located in the center of the specimen. The potential proposed by Basak et al. [C.B. Basak, A.K. Sengupta, H.S. Kamath, J. Alloys Compd. 360 (2003) 210216] was utilized to calculate interaction between atoms. The supplied kinetic energy was first spent to change the crystal structure into an amorphous one within a short period of about 0.3 ps, then it dissipated in the specimen. The amorphous track radius Ra was determined as a function of the effective stopping power gSe, i.e., the kinetic energy of atoms per unit length created by ion irradiation (Se: electronic stopping power, g: energy transfer ratio from stopping power to lattice vibration energy). It was found that the relationship between Ra and gSe follows the relation Ra2=aln(gS)+b. Compared to the case of Si and ?-cristobalite single crystals, it was harder to produce amorphous track because of the long range interaction between U atoms.

Sasajima, Y.; Osada, T.; Ishikawa, N.; Iwase, A.

2013-11-01

125

Anomalies in nonstoichiometric uranium dioxide induced by a pseudo phase transition of point defects  

NASA Astrophysics Data System (ADS)

A uniform distribution of point defects in an otherwise perfect crystallographic structure usually describes a unique pseudo phase of that state of a nonstoichiometric material. With off-stoichiometric uranium dioxide as a prototype, we show that analogous to a conventional phase transition, these pseudo phases will also transform from one state into another via changing the predominant defect species when external conditions of pressure, temperature, or chemical composition are varied. This exotic transition is numerically observed along shock Hugoniots and isothermal compression curves in UO2 with first-principles calculations. At low temperatures, it leads to anomalies (or quasidiscontinuities) in thermodynamic properties and electronic structures. In particular, the anomaly is pronounced in both shock temperature and the specific heat at constant pressure. With increasing temperature, however, it transforms gradually to a smooth crossover and becomes less discernible. The underlying physical mechanism and characteristics of this type of transition are encoded in the Gibbs free energy and are elucidated clearly by analyzing the correlation with the variation of defect populations as a function of pressure and temperature. The opportunities and challenges for a possible experimental observation of this phase change are also discussed.

Geng, Hua Y.; Song, Hong X.; Wu, Q.

2012-04-01

126

Molecular dynamics simulation of the surface properties of nanocrystalline uranium dioxide  

NASA Astrophysics Data System (ADS)

The molecular dynamics method is used to simulate the nanosized UO2 crystals. The phase-transition temperatures are calculated for the nanosized crystals of the uranium dioxide. It is demonstrated that the melting point and the temperature of the transition to the superionic state (melting of the anion sublattice) of the crystals decrease with decreasing sizes. In particular, melting point ( T m 2300 K) for the cubic nanocrystal with a size of 3.3 nm is lower than the melting point of the single crystal by almost 1000 K. The calculated surface energies are in agreement with the experimental results. The dependence of the surface energy on the size of the UO2 nanocrystals is obtained. The effect of the nanocrystal temperature on the surface energy is studied. The temperature dependence of the thickness of the melt layer is obtained in the framework of the model of the heterogeneous melting. The parameters and dependences can be used for the further analysis of the microstructure properties of nuclear fuel in working systems.

Makhmud-Akhunov, R. Yu.; Tikhonchev, M. Yu.; Svetukhin, V. V.

2013-08-01

127

Partition of soluble fission products between the grey phase, ZrO2 and uranium dioxide  

NASA Astrophysics Data System (ADS)

The energies to remove fission products from UO2 or UO2+x and incorporate them into BaZrO3, SrZrO3 (grey phase constituent phases) and ZrO2 have been calculated using atomistic scale simulation. These energies provide the thermodynamic drive for partition of soluble fission products between UO2 or UO2+x and these secondary oxide constituents of the fuel system. Tetravalent cation partition into BaZrO3, SrZrO3 and ZrO2 was only preferable for species with smaller radii than Zr4+, regardless of uranium dioxide stoichiometry. Under stoichiometric conditions both the larger and the smaller trivalent cations were found to segregate to BaZrO3 but only the smaller fuel additive elements Cr3+ and Fe3+ segregate to SrZrO3. Partition from UO2+x was always unfavourable for trivalent cations. Additions of excess Cr3+ (as a fuel additive) are predicted make the partition into BaZrO3 and SrZrO3 more favourable from UO2 for the larger trivalent cations. Trivalent fission products with radii smaller than or equal to that of Sm3+ were identified to segregate into ZrO2 only from UO2. No segregation to SrO or BaO is predicted.

Cooper, M. W. D.; Middleburgh, S. C.; Grimes, R. W.

2013-07-01

128

Method for Converting Uranium Oxides to Uranium Metal.  

National Technical Information Service (NTIS)

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...

W. K. Duerksen

1987-01-01

129

Process for electroslag refining of uranium and uranium alloys  

DOEpatents

A process is described for electroslag refining of uranium and uranium alloys wherein molten uranium and uranium alloys are melted in a molten layer of a fluoride slag containing up to about 8 weight percent calcium metal. The calcium metal reduces oxides in the uranium and uranium alloys to provide them with an oxygen content of less than 100 parts per million. (auth)

Lewis, P.S. Jr.; Agee, W.A.; Bullock, J.S. IV; Condon, J.B.

1975-07-22

130

Uranium Recovery from Seawater.  

National Technical Information Service (NTIS)

The objective of this study was to assess the feasibility of an electrochemical method of extracting uranium from seawater by laboratory experiments and analysis. The study also was directed at defining prospects for acquiring uranium by methods that resu...

M. J. Wooten C. Hirayama A. J. Panson J. T. Patton

1976-01-01

131

Uranium from phosphate ores  

SciTech Connect

The following topics are described briefly: the way phosphate fertilizers are made; how uranium is recovered in the phosphate industry; and how to detect covert uranium recovery operations in a phsophate plant.

Hurst, F.J.

1983-01-01

132

Uranium Mining in Australia.  

National Technical Information Service (NTIS)

Western world requirements for uranium based on increasing energy consumption and a changing energy mix, will warrant the development of Australia's resources. By 1985 Australian mines could be producing 9500 tonnes of uranium oxide yearly and by 1995 the...

G. A. Mackay

1978-01-01

133

NICKEL COATED URANIUM ARTICLE  

DOEpatents

Nickel coatings on uranium and various methods of obtaining such coatings are described. Specifically disclosed are such nickel or nickel alloy layers as barriers between uranium and aluminum- silicon, chromium, or copper coatings.

Gray, A.G.

1958-10-01

134

Cathodoluminescence of Uranium Oxides.  

National Technical Information Service (NTIS)

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation. (ERA citation 09:043913)

K. Winer C. Colmenares F. Wooten

1984-01-01

135

Cathodoluminescence of uranium oxides  

SciTech Connect

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

Winer, K.; Colmenares, C.; Wooten, F.

1984-08-09

136

EFFECT OF AMMONIUM DIURANATE PRECIPITATION CONDITIONS ON THE CHARACTERISTICS AND SINTERING BEHAVIOUR OF URANIUM DIOXIDE  

Microsoft Academic Search

Ammonium diurannte was prepared by adding aqueous ammonia to uranyl ; nitrate solution under different conditions of temperatare and final pH. The ; resulting precipitates, when dried, can be considered as loosely bound compounds ; with an ammonia\\/uranium ratio of 0: 37 containing varying amounts of water and ; ammonlum nitrate. As well as differing in composition, these precipitates differ

J. B. Ainscough; B. W. Oldfield

1962-01-01

137

Uranium industry annual 1995  

SciTech Connect

The Uranium Industry Annual 1995 (UIA 1995) provides current statistical data on the U.S. uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1995 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 period 1986 through 2005 as collected on the Form EIA-858, ``Uranium Industry Annual Survey``. Data collected on the ``Uranium Industry Annual Survey`` provide a comprehensive statistical characterization of the industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1995, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. Data on uranium raw materials activities for 1986 through 1995 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2005, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. The methodology used in the 1995 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. For the reader`s convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix D along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 14 figs., 56 tabs.

NONE

1996-05-01

138

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

139

PREPARATION OF URANIUM HEXAFLUORIDE  

DOEpatents

A process is described for preparing uranium hexafluoride from carbonate- leach uranium ore concentrate. The briquetted, crushed, and screened concentrate is reacted with hydrogen fluoride in a fluidized bed, and the uranium tetrafluoride formed is mixed with a solid diluent, such as calcium fluoride. This mixture is fluorinated with fluorine and an inert diluent gas, also in a fluidized bed, and the uranium hexafluoride obtained is finally purified by fractional distillation.

Lawroski, S.; Jonke, A.A.; Steunenberg, R.K.

1959-10-01

140

Method for converting uranium oxides to uranium metal  

SciTech Connect

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal.

Duerksen, W.K.

1988-01-05

141

PROCESS OF RECOVERING URANIUM  

Microsoft Academic Search

A method is presented for separating and recovering uranium from a ; complex mixure of impurities. The uranium is dissolved to produce an aqueous ; acidic solution including various impurities. In accordance with one method, ; with the uranium in the uranyl state, hydrogen cyanide is introduced into the ; solution to complex the impurities. Subsequently, ammonia is added to

Kilner

1959-01-01

142

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

143

PREPARATION OF URANIUM HEXAFLUORIDE  

Microsoft Academic Search

A process is described for preparing uranium hexafluoride from carbonate-; leach uranium ore concentrate. The briquetted, crushed, and screened concentrate ; is reacted with hydrogen fluoride in a fluidized bed, and the uranium ; tetrafluoride formed is mixed with a solid diluent, such as calcium fluoride. ; This mixture is fluorinated with fluorine and an inert diluent gas, also in

S. Lawroski; A. A. Jonke; R. K. Steunenberg

1959-01-01

144

PREPARATION OF URANIUM COMPOUNDS  

Microsoft Academic Search

Treatment of Mo- U alloys at an initial temperature of 100 to 300 deg C ; with a gaseous mixture of a hydrogen halide and molecular oxygen gives uranium ; oxide or a mixture of uranium oxyfluoride and uranium tetrafluoride that is\\/are ; substantially free from Mo. Hydriodic hydrobromic, hydro chloric, or ; hydrofluoric acids can be used as the

M. Bourgeois; P. Faugeras

1963-01-01

145

Uranium in Urine  

Microsoft Academic Search

DURING some work in this Research Department on compounds of uranium, as a safety precaution, we commenced to analyse the urine of personnel concerned, using a fluorimetric method. In the preparation of fluorimetric standards, known amounts of uranyl nitrate were added to samples of urine from persons not engaged on the work with uranium. To our surprise we found uranium

H. M. Wilson; A. A. Smales

1946-01-01

146

PRODUCTION OF URANIUM TETRAFLUORIDE  

DOEpatents

A method is presented for producing uranium tetrafluoride from the gaseous hexafluoride by feeding the hexafluoride into a high temperature zone obtained by the recombination of molecularly dissociated hydrogen. The molal ratio of hydrogen to uranium hexnfluoride is preferably about 3 to 1. Uranium tetrafluoride is obtained in a finely divided, anhydrous state.

Shaw, W.E.; Spenceley, R.M.; Teetzel, F.M.

1959-08-01

147

Dependence of the melting temperature on pressure up to 2000 bar in uranium dioxide, tungsten, and graphite  

SciTech Connect

The melting points of uranium dioxide, tungsten, and graphite were measured as a function of the isostatic pressure up to 2,000 bar (200 MPa), in a laser-heated autoclave filled with inert gas. The measured melting curves and their slopes were compared with predictions obtained from the Clausius-Clapeyron equation and existing thermochemical data of these substances. While for tungsten and graphite the results show reasonable agreement with the equilibrium thermodynamic calculations, the melting point of UO{sub 2} increases with pressure with a slope more than three times larger than expected.

Musella, M.; Ronchi, C.; Sheindlin, M.

1999-07-01

148

PROCESS OF RECOVERING URANIUM  

DOEpatents

A process is presented for recovering uranium values from calutron deposits. The process consists in treating such deposits to produce an oxidlzed acidic solution containing uranium together with the following imparities: Cu, Fe, Cr, Ni, Mn, Zn. The uranium is recovered from such an impurity-bearing solution by adjusting the pH of the solution to the range 1.5 to 3.0 and then treating the solution with hydrogen peroxide. This results in the precipitation of uranium peroxide which is substantially free of the metal impurities in the solution. The peroxide precipitate is then separated from the solution, washed, and calcined to produce uranium trioxide.

Carter, J.M.; Larson, C.E.

1958-10-01

149

High loading uranium plate  

SciTech Connect

Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pari of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat hiving a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

Wiencek, T.C.; Domagala, R.F.; Thresh, H.R.

1990-10-16

150

URANIUM RECOVERY PROCESS  

DOEpatents

In the prior art processing of uranium ores, the ore is flrst digested with nitric acid and filtered, and the uranium values are then extracted tom the filtrate by contacting with an organic solvent. The insoluble residue has been processed separately in order to recover any uranium which it might contain. The improvement consists in contacting a slurry, composed of both solution and residue, with the organic solvent prior to filtration. Tbe result is that uranium values contained in the residue are extracted along with the uranium values contained th the solution in one step.

Yeager, J.H.

1958-08-12

151

URANIUM COMPATABILITY STUDIES. PART 6. THE PRODUCTS AND MECHANISM OF THE URANIUM--WATER AND URANIUM HYDRIDE--WATER REACTIONS  

Microsoft Academic Search

Uranium and water react to form hydrogen and a solid product containing non-stoichiometric uranium dioxide, UO{sub 2.06 +- 0.02}, and 2 - 9% UH. The relative amounts of the products vary with the pressure of water vapour and to a smaller extent with the temperature and batch of uranium, but are independent of hydrogen pressure and reaction time. The UH

M. M. Baker; L. N. Less; S. Orman

1965-01-01

152

Method for converting uranium oxides to uranium metal  

SciTech Connect

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

153

Method for converting uranium oxides to uranium metal  

SciTech Connect

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)

1988-01-01

154

Welding of uranium and uranium alloys  

SciTech Connect

The major reported work on joining uranium comes from the USA, Great Britain, France and the USSR. The driving force for producing this technology base stems from the uses of uranium as a nuclear fuel for energy production, compact structures requiring high density, projectiles, radiation shielding, and nuclear weapons. This review examines the state-of-the-art of this technology and presents current welding process and parameter information. The welding metallurgy of uranium and the influence of microstructure on mechanical properties is developed for a number of the more commonly used welding processes.

Mara, G.L.; Murphy, J.L.

1982-03-26

155

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

156

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2013 CFR

... 3 2013-07-01 2013-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2013-07-01

157

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2010 CFR

... 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2010-07-01

158

31 CFR 540.317 - Uranium feed; natural uranium feed.  

Code of Federal Regulations, 2010 CFR

... 3 2009-07-01 2009-07-01 false Uranium feed; natural uranium feed. 540.317 Section 540.317 Money...CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...

2009-07-01

159

PROCESS FOR PRODUCING URANIUM HEXAFLUORIDE  

DOEpatents

A process for the production of uranium hexafluoride from the oxides of uranium is reported. In accordance with the method the higher oxides of uranium may be reduced to uranium dioxide (UO/sub 2/), the latter converted into uranium tetrafluoride by reaction with hydrogen fluoride, and the UF/sub 4/ convented to UF/sub 6/ by reaction with a fluorinating agent. The UO/sub 3/ or U/sub 3/O/sub 8/ is placed in a reaction chamber in a copper boat or tray enclosed in a copper oven, and heated to 500 to 650 deg C while hydrogen gas is passed through the oven. The oven is then swept clean of hydrogen and the water vapor formed by means of nitrogen and then while continuing to maintain the temperature between 400 and 600 deg C, anhydrous hydrogen fluoride is passed through. After completion of the conversion to uranium tetrafluoride, the temperature of the reaction chamber is lowered to ahout 400 deg C, and elemental fluorine is used as the fluorinating agent for the conversion of UF/sub 4/ into UF/sub 6/. The fluorine gas is passed into the chamber, and the UF/sub 6/ formed passes out and is delivered to a condenser.

Fowler, R.D.

1957-10-22

160

Uranium purchases report 1992  

SciTech Connect

Data reported by domestic nuclear utility companies in their responses to the 1991 and 1992 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B ``Uranium Marketing Activities,are provided in response to the requirements in the Energy Policy Act 1992. Data on utility uranium purchases and imports are shown on Table 1. Utility enrichment feed deliveries and secondary market acquisitions of uranium equivalent of US DOE separative work units are shown on Table 2. Appendix A contains a listing of firms that sold uranium to US utilities during 1992 under new domestic purchase contracts. Appendix B contains a similar listing of firms that sold uranium to US utilities during 1992 under new import purchase contracts. Appendix C contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data.

Not Available

1993-08-19

161

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

162

Separation of Zirconium and Uranium.  

National Technical Information Service (NTIS)

This invention relates to separation and recovery of zirconium from aqueous solutions containing zirconium and uranium. Separation of zirconium from uranium is, however, difficult since the uranium tends to accompany the zirconium in the solvent extractio...

H. G. Henry

1981-01-01

163

Five-year inhalation study with natural uranium dioxide (UO) dust. II. Postexposure retention and biologic effects in the monkey, dog, and rat  

Microsoft Academic Search

Inhalation studies show that dogs, monkeys, and rats can breathe a ; natural uranium dioxide aerosol of approximately 1 mu m mass median particle ; diameter at a mean concentration of 5 mg U\\/m³ (25 x Threshold Limit Value ; or 28 x Maximum Permissible Concentration in Air) for periods as long as 5 yr ; with little evidence of

Leonard J. Leach; Charles L. Yuile; Harold C. Hodge; George E. Sylvester; Herbert B. Wilson

1973-01-01

164

Ex-Reactor Determination of Thermal Gap and Contact Conductance between Uranium Dioxide: Zircaloy-4 Interfaces. Stage I: Low Gas Pressure.  

National Technical Information Service (NTIS)

A study of thermal gap and contact conductance between depleted uranium dioxide (UO2) and Zircaloy-4 (Zr4) has been made using two measurement apparatuses developed as part of this program. Both gap and contact conductance experiments were performed using...

J. E. Garnier S. Begej

1979-01-01

165

Depleted uranium dioxide melting in cold crucible melter and production of granules from the melt for use in casks for spent nuclear fuel and radioactive wastes  

Microsoft Academic Search

Available in abstract form only. Full text of publication follows: This paper describes the results of joint research program of Russian Research Institute of Chemical Technology and Oak Ridge National Laboratory to develop new materials for build spent nuclear fuel (SNF) storage, transport, and disposal casks using shielding made with depleted uranium dioxide (DUO) in a DUO-steel cermet or a

Vitaly Gotovchikov; V. A. Seredenko; V. V. Shatalov; B. S. Mironov; V. N. Kaplenkov; A. V. Seredenko; V. K. Saranchin; A. S. Shulgin; Danila Kalmakov; M. J. Haire; C. W. Forsberg

2007-01-01

166

COATING URANIUM FROM CARBONYLS  

DOEpatents

Methods are described for making adherent corrosion resistant coatings on uranium metal. According to the invention, the uranium metal is heated in the presence of an organometallic compound such as the carbonyls of nickel, molybdenum, chromium, niobium, and tungsten at a temperature sufficient to decompose the metal carbonyl and dry plate the resultant free metal on the surface of the uranium metal body. The metal coated body is then further heated at a higher temperature to thermally diffuse the coating metal within the uranium bcdy.

Gurinsky, D.H.; Storrs, S.S.

1959-07-14

167

URANIUM LEACHING AND RECOVERY PROCESS  

DOEpatents

A process is described for recovering uranium from carbonate leach solutions by precipitating uranium as a mixed oxidation state compound. Uranium is recovered by adding a quadrivalent uranium carbon;te solution to the carbonate solution, adjusting the pH to 13 or greater, and precipitating the uranium as a filterable mixed oxidation state compound. In the event vanadium occurs with the uranium, the vanadium is unaffected by the uranium precipitation step and remains in the carbonate solution. The uranium-free solution is electrolyzed in the cathode compartment of a mercury cathode diaphragm cell to reduce and precipitate the vanadium.

McClaine, L.A.

1959-08-18

168

Uranium industry annual 1993  

SciTech Connect

Uranium production in the United States has declined dramatically from a peak of 43.7 million pounds U{sub 3}O{sub 8} (16.8 thousand metric tons uranium (U)) in 1980 to 3.1 million pounds U{sub 3}O{sub 8} (1.2 thousand metric tons U) in 1993. This decline is attributed to the world uranium market experiencing oversupply and intense competition. Large inventories of uranium accumulated when optimistic forecasts for growth in nuclear power generation were not realized. The other factor which is affecting U.S. uranium production is that some other countries, notably Australia and Canada, possess higher quality uranium reserves that can be mined at lower costs than those of the United States. Realizing its competitive advantage, Canada was the world`s largest producer in 1993 with an output of 23.9 million pounds U{sub 3}O{sub 8} (9.2 thousand metric tons U). The U.S. uranium industry, responding to over a decade of declining market prices, has downsized and adopted less costly and more efficient production methods. The main result has been a suspension of production from conventional mines and mills. Since mid-1992, only nonconventional production facilities, chiefly in situ leach (ISL) mining and byproduct recovery, have operated in the United States. In contrast, nonconventional sources provided only 13 percent of the uranium produced in 1980. ISL mining has developed into the most cost efficient and environmentally acceptable method for producing uranium in the United States. The process, also known as solution mining, differs from conventional mining in that solutions are used to recover uranium from the ground without excavating the ore and generating associated solid waste. This article describes the current ISL Yang technology and its regulatory approval process, and provides an analysis of the factors favoring ISL mining over conventional methods in a declining uranium market.

Not Available

1994-09-01

169

The Metabolism of Ceramic and Non-ceramic Forms of Uranium Dioxide after Deposition in the Rat Lung  

Microsoft Academic Search

Ceramic and non-ceramic forms of uranium dixoide, produced industrially, were administered to rats either by inhalation or as an aqueous suspension which was injected directly into the pulmonary region of the lungs. The results showed that:1 both materials should be assigned to inhalation class Y as defined by the International Commission on Radiological Protection;2 whilst the translocation of uranium to

G. N. Stradling; J. W. Stather; S. A. Gray; J. C. Moody; A. Hodgson; D. Sedgwick; N. Cooke

1988-01-01

170

URANIUM SEPARATION PROCESS  

DOEpatents

The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

McVey, W.H.; Reas, W.H.

1959-03-10

171

DECONTAMINATION OF URANIUM  

DOEpatents

A process is given for separating fission products from uranium by extracting the former into molten aluminum. Phase isolation can be accomplished by selectively hydriding the uranium at between 200 and 300 deg C and separating the hydride powder from coarse particles of fissionproduct-containing aluminum. (AEC)

Spedding, F.H.; Butler, T.A.

1962-05-15

172

The international uranium market  

Microsoft Academic Search

This book reviews the history of the world uranium industry and analyzes the present economic and political forces shaping export policies, pricing, inventories, investment, and security measures. The technical structure of the nuclear fuel-supply system is examined and the implications of this structure for uranium and nuclear fuel supply and demand are explored. Topics considered include fuel-cycle economics, the trends

Neff

1984-01-01

173

Uranium in river water  

Microsoft Academic Search

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

M. R. Palmer; J. M. Edmond

1993-01-01

174

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.

175

Transporting uranium fuels  

Microsoft Academic Search

The transport of nuclear materials is often overlooked when viewing the front-end of the nuclear fuel cycle. However, when book transfers are not practical, a well-managed transport program is a significant factor in customer satisfaction for nuclear fuel purchases. Some of the logistical considerations of transporting uranium concentrates and uranium hexafluoride include which type of cylinders to use for transport,

J. D. Price; A. L. Wolcott

1992-01-01

176

Uranium hexafluoride for enrichment  

SciTech Connect

The specification applies to uranium hexafluoride containing uranium of any U-235 concentration that is intended for a feed material to a gaseous diffusion plant. The specification includes isotopic content, chemical requirements, methods of chemical and isotopic analysis, packaging, handling, and shipping. (JMT)

Not Available

1981-01-01

177

Uranium purchases report 1994.  

National Technical Information Service (NTIS)

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 purch...

1995-01-01

178

Prospects for uranium enrichment  

Microsoft Academic Search

It is pointed out that the lack of suitable lasers constitutes the biggest technological barrier to practical laser techniques for the enrichment of uranium isotopes. Costs of laser isotope-separation techniques are compared with those of other approaches, taking into account as a basis conservative extrapolations of existing laser technology. Attention is given to the demand for enriched uranium, the types

R. J. Jensen; J. G. Marinuzzi; C. P. Robinson; S. D. Rockwood

1976-01-01

179

PREPARATION OF URANIUM TRIOXIDE  

Microsoft Academic Search

The production of uranium trioxide from aqueous solutions of uranyl ; nitrate is discussed. The uranium trioxide is produced by adding sulfur or a ; sulfur-containing compound, such as thiourea, sulfamic acid, sulfuric acid, and ; ammonium sulfate, to the uranyl solution in an amount of about 0.5% by weight of ; the uranyl nitrate hexahydrate, evaporating the solution to

Buckingham

1959-01-01

180

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

181

Another Comeback for Uranium  

Microsoft Academic Search

The uranium market has been unstable since private industry entered the nuclear power generating business in the early 1960s. Uranium supply has always exceeded demand throughout the Free World. In 1982, production was 106 million pounds U308 and accumulated inventory totaled over 400 million pounds; consumption was only 63 million pounds. Recent inventory selling, production cutbacks and producers buying from

T. A. Boyden

1983-01-01

182

Thermal conductivity of uranium dioxide up to 2900 K from simultaneous measurement of the heat capacity and thermal diffusivity  

NASA Astrophysics Data System (ADS)

The thermal diffusivity and heat capacity of uranium dioxide have been measured from 500 to 2900 K with an advanced laser-flash technique. These two quantities were determined simultaneously by means of an accurate numerical fitting of the experimental thermograms. At high temperatures the precision of the method used is much better than that associated with conventional laser-flash measurements. It was found that the heat capacity continues to increase even at temperatures above the expected lambda transition (2670 K). The inverse of the thermal diffusivity increases linearly with temperature up to 2600 K, whilst at higher temperatures the slope markedly decreases. A new expression for the thermal conductivity as a function of temperature is proposed, which is corroborated by some theoretical considerations on the underlying heat transport mechanisms.

Ronchi, C.; Sheindlin, M.; Musella, M.; Hyland, G. J.

1999-01-01

183

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

NASA Astrophysics Data System (ADS)

Thermophysical properties of uranium dioxide are investigated by classical molecular dynamics for temperatures from 300 K to 3000 K. An increase of specific heat in the temperature range from 1300 K to 2500 K 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 specific heat and high ionic conductivity are investigated. We show that one more important feature was left unnoticed: the rise in the lattice contribution to thermal conductivity at high temperatures. An explanation is provided for this effect which is specific to superionic conductors. Reasonable agreement with experimental data up to 3000 K is obtained for thermal conductivity, even in the absence of electronic excitations.

Lunev, Artem V.; Tarasov, Boris A.

2011-08-01

184

A NRA study of temperature and heavy ion irradiation effects on helium migration in sintered uranium dioxide  

NASA Astrophysics Data System (ADS)

Helium implanted uranium dioxide sintered samples were studied using nuclear reaction analysis prior to and following heavy ion irradiations and temperature anneals at 800 C and 1100 C. The results show that the heavy ion irradiations do not produce measurable long range movement of helium atoms. However, the ion irradiations do affect the behaviour of helium during subsequent temperature anneals. As regards the 800 C anneal, the reduced mobility of helium in the ion-irradiated samples is interpreted as resulting from enhanced helium atom segregation produced by the ion-irradiation. Conversely at 1100 C, the initial heavy ion irradiation appears to produce a greater than expected movement of helium within the bulk of the sample which could be an indication of defect assisted helium diffusion. Thermal diffusion coefficients are also reported at 800 C and 1100 C based on an analysis using a one-dimensional diffusion model.

Martin, G.; Garcia, P.; Labrim, H.; Sauvage, T.; Carlot, G.; Desgardin, P.; Barthe, M. F.; Piron, J. P.

2006-10-01

185

Melting and casting of uranium and uranium alloys  

Microsoft Academic Search

Uranium and uranium alloys are typically vacuum induction melted in graphite crucibles, but due to the chemical reactivity of uranium and most alloying elements with carbon, a protective coating is generally applied to the crucibles. The form of the melting stock and final ingot shape may also influence the specific melting technique chosen. The major impurities in uranium are iron,

N. C. Jr

1982-01-01

186

Jabiluka uranium project  

SciTech Connect

The Jabiluka uranium and gold deposit located in the Northern Territory of Australia is the world's largest known primary uranium deposits and as such has the potential to become one of the most important uranium projects in the world. Despite the financial and structural challenges facing the major owner Pancontinental Mining Limited and the changing political policies in Australia, Jabiluka is well situated for development during the 1990's. With the availability of numerous financial and development alternatives, Jabiluka could, by the turn of the century, take its rightful place among the first rank of world uranium producers. The paper discusses ownership, location, property rights, licensing, environmental concerns, marketing and development, capital costs, royalties, uranium policy considerations, geologic exploration history, regional and site geology, and mining and milling operations.

Not Available

1991-05-01

187

URANIUM PRECIPITATION PROCESS  

DOEpatents

A method for the recovery of uranium from sulfuric acid solutions is described. In the present process, sulfuric acid is added to the uranium bearing solution to bring the pH to between 1 and 1.8, preferably to about 1.4, and aluminum metal is then used as a reducing agent to convert hexavalent uranium to the tetravalent state. As the reaction proceeds, the pH rises amd a selective precipitation of uranium occurs resulting in a high grade precipitate. This process is an improvement over the process using metallic iron, in that metallic aluminum reacts less readily than metallic iron with sulfuric acid, thus avoiding consumption of the reducing agent and a raising of the pH without accomplishing the desired reduction of the hexavalent uranium in the solution. Another disadvantage to the use of iron is that positive ferric ions will precipitate with negative phosphate and arsenate ions at the pH range employed.

Thunaes, A.; Brown, E.A.; Smith, H.W.; Simard, R.

1957-12-01

188

Method of recovering uranium  

SciTech Connect

Uranium is recovered from a carbonate leach solution containing a dissolved uranium salt and a monovalent ion. The pH of the leach solution is adjusted to about 5 to about 7.5, and preferably to about 6 to about 7. Phosphate ion is then added to typical in-situ leach solutions in an amount from about 10 to about 30 mole % in excess of the amount needed to stoichiometrically react with the uranium in said solution. This results in the precipitation of a compound made up of the monovalent ion, uranium, and the phosphate ion, which is insoluble in the solution. The precipitate is then separated from the solution preferably by means of a centrifuge or a vortex clarifier. It can then be dissolved in acid, and the uranium extracted into an organic solvent such as DEHPA-TOPA in kerosene.

Camp, F.E.; Swartzlander, A.B.

1984-10-09

189

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

190

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

191

Electrochemical properties of uranium in lactones: Kinetics and electrodeposition  

Microsoft Academic Search

The electrochemical reductions of hexavalent and tetravalent uranium are reported in -butyrolactone, -valerolactone, -octanoiclactone and in the mixed solvent -butyrolactone\\/tetrahydrofuran. The transient techniques foresee either the formation of uranium dioxide or uranium metal according to a two-step reduction but the presence of these cathodic products is difficult to ascertain in controlled potential electrolysis. While mixing a lactone with tetrahydrofuran, the

L. Martinot; L. Lopes; B. Andrianne; F. Gilet; F. Lebon

1994-01-01

192

Chemical reactivity of oxide materials with uranium and uranium trichloride  

Microsoft Academic Search

A graphite crucible is used for the manufacturing of uranium ingots in the uranium casting equipment of the electrorefining\\u000a process. Uranium and uranium alloys are typically induction melted in graphite crucibles under a vacuum condition; however,\\u000a due to the chemical reactivity of uranium and most alloying elements with carbon, a protective ceramic coating is generally\\u000a applied to the graphite crucibles.

Sung Ho Lee; Choon Ho Cho; Yoon Sang Lee; Han Soo Lee; Jeong-Guk Kim

2010-01-01

193

THE DEVELOPMENT OF A HIGH CAPACITY, CONTINUOUS PROCESS FOR THE PREPARATION OF URANIUM HEXAFLUORIDE FROM URANIUM OXIDES AND ORE CONCENTRATES  

Microsoft Academic Search

Methods and equipment were successfully developed for converting uranium ; oxides to uranium hexafluoride continuously and economically. The process ; involves a series of three highly exothermic reactions in which uranium triioxide ; is converted to dioxide with hydrogen to tetrafluoridc with anhydrous hydrogen ; fluoride. and finally to hexafluoride with fluorine. The hexafluoride can be ; recovered by solid

S. H. Smiley; D. C. Brater

1958-01-01

194

PROCESS OF RECOVERING URANIUM  

DOEpatents

A method is presented for separating and recovering uranium from a complex mixure of impurities. The uranium is dissolved to produce an aqueous acidic solution including various impurities. In accordance with one method, with the uranium in the uranyl state, hydrogen cyanide is introduced into the solution to complex the impurities. Subsequently, ammonia is added to the solution to precipitate the uraniunn as ammonium diuranate away from the impurities in the solution. Alternatively, the uranium is precipitated by adding an alkaline metal hydroxide. In accordance with the second method, the uranium is reduced to the uranous state in the solution. The reduced solution is then treated with solid alkali metal cyanide sufficient to render the solution about 0.1 to 1.0 N in cyanide ions whereat cyanide complex ions of the metal impurities are produced and the uranium is simultaneously precipituted as uranous hydroxide. Alternatively, hydrogen cyanide may be added to the reduced solution and the uranium precipitated subsequently by adding ammonium hydroxide or an alkali metal hydroxide. Other refinements of the method are also disclosed.

Kilner, S.B.

1959-12-29

195

Mining of Uranium in Kazakhstan  

Microsoft Academic Search

\\u000a Approximately one-fifth of the world uranium reserves are found in Kazakhstan. Deposits are divided among six uranium ore\\u000a provinces according to geological positions, generic features and territorial location. Characteristics of uranium mineralization\\u000a of deposits are given. In-situ leaching (ISL) technology of uranium recovery from low-grade ore of sand-stone deposits is\\u000a given and based on selective dissolving of uranium bearing minerals.

Gulzhan Ospanova; Ivan Mazalov; Zhaksylyk Alybayev

196

Depleted uranium management alternatives  

SciTech Connect

This report evaluates two management alternatives for Department of Energy depleted uranium: continued storage as uranium hexafluoride, and conversion to uranium metal and fabrication to shielding for spent nuclear fuel containers. The results will be used to compare the costs with other alternatives, such as disposal. Cost estimates for the continued storage alternative are based on a life-cycle of 27 years through the year 2020. Cost estimates for the recycle alternative are based on existing conversion process costs and Capital costs for fabricating the containers. Additionally, the recycle alternative accounts for costs associated with intermediate product resale and secondary waste disposal for materials generated during the conversion process.

Hertzler, T.J.; Nishimoto, D.D.

1994-08-01

197

On the melting behaviour of uranium/plutonium mixed dioxides with high-Pu content: A laser heating study  

NASA Astrophysics Data System (ADS)

The melting behaviour of mixed uranium-plutonium dioxides (MOX) has been investigated by laser heating under controlled atmosphere in the PuO2-rich composition range (with amount-of-substance fraction x(PuO2) ?75%). The observed solidus/liquidus points are in agreement with the newly measured melting point of pure plutonium dioxide (3017 K). They suggest the existence of a minimum freezing temperature at a composition x(PuO2) between 50% and 80%, in contrast with earlier research carried out with traditional furnace heating methods. The current results have been obtained under optimised experimental conditions aimed at maintaining the integrity and original composition of the samples throughout the laser heating cycles. With this goal in mind, experiments have been carried out under controlled gas pressure (pressurised air or argon) and short time duration (<0.25 s). A critical discussion of the present results highlights the fact that the formation of the gas phase has to be taken into account in the study of the high-Pu MOX behaviour at high temperature. The experimental results obtained thus correspond to slightly hypo-stoichiometric (U, Pu)O2-x compositions in equilibrium with the gas phase.

De Bruycker, F.; Boboridis, K.; Konings, R. J. M.; Rini, M.; Eloirdi, R.; Guneau, C.; Dupin, N.; Manara, D.

2011-12-01

198

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

2011-03-29

199

Migration energies of native defects and fission products in uranium dioxide  

NASA Astrophysics Data System (ADS)

Despite the importance of fission products like Xe in nuclear fuels, the mechanism of how these atoms diffuse in the lattice is not known. In an effort to identify this mechanism, we have used density functional theory as well as a variety of different classical potentials for to study the migration energies of a variety of atomic steps in UO2, with and without Xe impurities and native defects. We find that the classical potential of Basak gives results which compare favorably with density functional theory for the diffusion of a Schottky defect cluster. We observe a new path for xenon-tetravacancy (a UO2 Schottky defect plus an additional U vacancy) motion using molecular dynamics. This path has a lower energy barrier than previously reported xenon-tetravacancy paths. We examine the possibility of a uranium vacancy dissociating from the xenon-tetravacancy cluster and find that large barriers for this dissociation. We also calculate xenon-double Schottky defect migration and find it has a slightly larger barrier than xenon-tetravacancy motion with the oxygen vacancies being weakly bound to the defect.

Thompson, Alexander; Wolverton, Chris

2011-03-01

200

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

201

On the role of strong electron correlations in the surface properties and chemistry of uranium dioxide.  

PubMed

We report density functional calculations of the surface properties and chemistry of UO(2)(111) performed within the generalized gradient approximation corrected with an effective Hubbard parameter (GGA + U within Dudarev's formalism) to account for the strong on-site Coulomb repulsion between U 5f electrons. The variation of the properties of periodic slab models, with collinear ferromagnetic and antiferromagnetic arrangements of the uranium magnetic moments, was investigated while ramping up the effective Hubbard parameter from U(eff) = 0 eV, corresponding to standard density functional theory, up to U(eff) = 4 eV, the value that correctly reproduces the antiferromagnetic ground state of bulk UO(2). The chemical interactions of molecular water, dissociated water, dissociated oxygen and co-adsorbed molecular water and monatomic oxygen with the UO(2)(111) surface were also studied as functions of the U(eff) parameter. Calculations reveal that some of the key electronic and chemical properties controlling the surface reactivity are very sensitive to the value of this strong electron correlation parameter. PMID:23354003

Weck, Philippe F; Kim, Eunja; Jov-Coln, Carlos F; Sassani, David C

2013-04-01

202

Uranium in alkaline rocks  

SciTech Connect

Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential.

Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

1978-04-01

203

300 AREA URANIUM CONTAMINATION  

SciTech Connect

{sm_bullet} Uranium fuel production {sm_bullet} Test reactor and separations experiments {sm_bullet} Animal and radiobiology experiments conducted at the. 331 Laboratory Complex {sm_bullet} .Deactivation, decontamination, decommissioning,. and demolition of 300 Area facilities

BORGHESE JV

2009-07-02

204

Uranium purchases report 1993  

SciTech Connect

Data reported by domestic nuclear utility companies in their responses to the 1991 through 1993 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B,`` Uranium Marketing Activities,`` are provided in response to the requirements in the Energy Policy Act 1992. Appendix A contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data. Additional information published in this report not included in Uranium Purchases Report 1992, includes a new data table. Presented in Table 1 are US utility purchases of uranium and enrichment services by origin country. Also, this report contains additional purchase information covering average price and contract duration. Table 2 is an update of Table 1 and Table 3 is an update of Table 2 from the previous year`s report. The report contains a glossary of terms.

Not Available

1994-08-10

205

Uranium hexafluoride handling. Proceedings.  

National Technical Information Service (NTIS)

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 inf...

1991-01-01

206

Advanced Uranium Enrichment Processes.  

National Technical Information Service (NTIS)

Three advanced Uranium enrichment processes are dealt with in the report: AVLIS (Atomic Vapour LASER Isotope Separation), MLIS (Molecular LASER Isotope Separation) and PSP (Plasma Separation Process). The description of the physical and technical features...

M. Clerc P. Plurien

1986-01-01

207

Method of recovering uranium  

Microsoft Academic Search

Uranium is recovered from a carbonate leach solution containing a dissolved uranium salt and a monovalent ion. The pH of the leach solution is adjusted to about 5 to about 7.5, and preferably to about 6 to about 7. Phosphate ion is then added to typical in-situ leach solutions in an amount from about 10 to about 30 mole %

F. E. Camp; A. B. Swartzlander

1984-01-01

208

Worldwide developments in uranium  

SciTech Connect

World uranium production will continue to change in most major producing nations. Canadian production will increase and will be increasingly dominated by western producers as eastern Canadian high-cost production declines. Australian production will increase as major projects come into operation before 2000. US production will stabilize through the end of the century. South African production will be dependent upon the worldwide support for economic sanctions. China's entry into the world market injects yet another variable into the already cloudy supply picture. Many risks and uncertainties will face uranium producers through the 1980s. Recognizing that the uranium industry is not a fast-growing market, many existing and potential producers are seeking alternate investment courses, causing a restructuring of the world uranium production industry in ways not anticipated even a few years ago. During the restructuring process, world uranium production will most likely continue to exceed uranium consumption, resulting in a further buildup of world uranium inventories. Inventory sales will continue to redistribute this material. As inventory selling runs its course, users will turn to normal sources of supply, stimulating additional production to meet needs. Stimulation in the form of higher prices will be determined by how fast producers are willing and able to return to the market. Production costs are expected to have an increasing impact as it has become apparent that uranium resources are large in comparison to projected consumption. Conversely, security-of-supply issues have seemed to be of decreasing magnitude as Canada, Australia, and other non-US producers continue to meet delivery commitments.

Hoellen, E.E.

1987-05-01

209

URANIUM SEPARATION PROCESS  

DOEpatents

A method of separating uranium oxides from PuO/sub 2/, ThO/sub 2/, and other actinide oxides is described. The oxide mixture is suspended in a fused salt melt and a chlorinating agent such as chlorine gas or phosgene is sparged through the suspension. Uranium oxides are selectively chlorinated and dissolve in the melt, which may then be filtered to remove the unchlorinated oxides of the other actinides. (AEC)

Lyon, W.L.

1962-04-17

210

URANIUM EXTRACTION PROCESS  

DOEpatents

A process is described for recovering uranium values from acidic aqueous solutions containing hexavalent uranium by contacting the solution with an organic solution comprised of a substantially water-immiscible organlc diluent and an organic phosphate to extract the uranlum values into the organic phase. Carbon tetrachloride and a petroleum hydrocarbon fraction, such as kerosene, are sultable diluents to be used in combination with organlc phosphates such as dibutyl butylphosphonate, trlbutyl phosphine oxide, and tributyl phosphate.

Baldwin, W.H.; Higgins, C.E.

1958-12-16

211

Method for the recovery of uranium values from uranium tetrafluoride  

DOEpatents

The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions whereas the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

Kreuzmann, A.B.

1982-10-27

212

Method for the recovery of uranium values from uranium tetrafluoride  

DOEpatents

The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions wherein the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

Kreuzmann, Alvin B. (Cincinnati, OH)

1983-01-01

213

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Uranium enrichment. 540.316 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium...

2013-07-01

214

Interaction of uranium with nitrate melts  

SciTech Connect

Interaction of metallic uranium with a eutectic mixture of KNO/sub 3/-NaNO/sub 3/ melt at 234-510/sup 0/C in an inert atmosphere is studied. It is shown that the degree of uranium oxidation depends on the melt temperature. At 236-367/sup 0/C uranium dioxide is formed; the latter undergoes oxidation to diuranate at a higher temperature. The interaction is accompanied by accumulation of alkali metal nitrates in a nitrate melt and by NO/sub 2/ evolution.

Denisov, V.P.; Korobeinikov, I.V.; Kutyrev, K.N.; Pyatkov, V.I.; Raspopin, S.P.

1987-07-01

215

Reprocessed uranium exposure and lung cancer risk.  

PubMed

This study investigated the risk of lung cancer in regards to protracted occupational exposure to reprocessed uranium compounds. Two thousand seven hundred and nine male workers employed at the AREVA NC uranium processing plant between 1960 and 2005 in France were included in the cohort. Historical exposure to reprocessed uranium compounds classified by their solubility type was assessed on the basis of the plant's specific job-exposure matrix. Cox proportional hazard models adjusted for attained age, calendar period, and socioeconomic status were used to estimate relative risks in regards of each type of uranium compound. The relative risk of lung cancer tended to increase with decreasing solubility of reprocessed uranium compounds. The highest-though not statistically significant-relative risk was observed among workers exposed to slowly soluble reprocessed uranium dioxide. This study is the first suggesting an increasing risk of lung cancer associated with exposure to reprocessed uranium. Our results are consistent with data from experimental studies of biokinetics and the action mechanism of slowly soluble uranium compounds, but need to be confirmed in larger studies with more detailed dose-response analyses. PMID:20699691

Canu, Irina Guseva; Jacob, Sophie; Cardis, Elisabeth; Wild, Pascal; Car-Lorho, Sylvaine; Auriol, Bernard; Laurier, Dominique; Tirmarche, Margot

2010-09-01

216

Process for electrolytically preparing uranium metal  

DOEpatents

A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

Haas, Paul A. (Knoxville, TN)

1989-01-01

217

Vaporization of Uranium Mononitride and Heat of Sublimation of Uranium  

Microsoft Academic Search

The vaporization of uranium mononitride UN has been investigated by the Knudsen effusion technique in combination with a mass spectrometer. The vaporization occurs incongruently by preferential loss of nitrogen forming the two-phase system nitrogen-saturated liquid uraniumuranium-saturated nonstoichiometric uranium mononitride. The vapor pressures of U and N2 have been obtained by silver calibration over the two-phase system UN0.4&sngbnd;UN0.9 in the temperature

Karl A. Gingerich

1969-01-01

218

Pyrophoric behaviour of uranium hydride and uranium powders  

Microsoft Academic Search

Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (<0.5wt.%) was obtained by heat treatment at low temperature in flowing Ar\\/5%H2. Pure uranium powder was

F. Le Guyadec; X. Gnin; J. P. Bayle; O. Dugne; A. Duhart-Barone; C. Ablitzer

2010-01-01

219

Comment on ``Interplay of defect cluster and the stability of xenon in uranium dioxide from density functional calculations''  

NASA Astrophysics Data System (ADS)

Geng [H. Y. Geng, Y. Chen, Y. Kaneta, M. Kinoshita, and Q. Wu, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.82.094106 82, 094106 (2010)] recently reported DFT+U calculations of xenon behavior in uranium dioxide UO2. One of the main conclusions of their work is that the quasiannealing (QA) procedure allowed them to avoid metastable states created by the DFT+U approximation. However, based on a comparison of total energies, they stated that an incomplete implementation of occupation matrix control (OMC) had been done in our previous work [B. Dorado, G. Jomard, M. Freyss, and M. Bertolus, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.82.035114 82, 035114 (2010)] and that we failed to reach the ground state of the perfect UO2 fluorite structure. In this Comment, we show that the discrepancy they observed does not stem from an incomplete implementation of OMC, but from the calculation of the compensation charge used in the projector augmented-wave formalism.

Dorado, Boris; Amadon, Bernard; Jomard, Grald; Freyss, Michel; Bertolus, Marjorie

2011-09-01

220

Enhanced thermal conductivity of uranium dioxidesilicon 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 UO2SiC 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 UO2SiC composites.

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

2013-02-01

221

Conversion of uranium hexafluoride to oxides of uranium  

Microsoft Academic Search

In a process for the conversion of uranium hexafluoride to a uranium oxide by injecting uranium hexafluoride and dry steam into a first region of a vessel so as to form a plume of particles of uranyl fluoride and reacting the uranyl fluoride in a second region of the vessel with a countercurrent flow of steam and\\/or hydrogen the operation

G. Butler; G. Gillies; T. Heal; J. Littlechild

1983-01-01

222

Separation of Zirconium and Uranium.  

National Technical Information Service (NTIS)

Zirconium- and uranium-containing hydrocarbon-amine solutions are treated for separation of zirconium and uranium by means of a process comprising: (1) selctive stripping of zirconium with an aqueous chloride solution, and (2) scrubbing the resulting aque...

D. J. MacDonald H. G. Henry

1982-01-01

223

Cathodoluminescence of uranium oxides*1  

Microsoft Academic Search

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

K. Winer; C. Colmenares; F. Wooten

1984-01-01

224

Microbial reduction of uranium  

USGS Publications Warehouse

REDUCTION of the soluble, oxidized form of uranium, U(VI), to insoluble U(IV) is an important mechanism for the immobilization of uranium in aquatic sediments and for the formation of some uranium ores1-10. U(VI) reduction has generally been regarded as an abiological reaction in which sulphide, molecular hydrogen or organic compounds function as the reductant1,2,5,11. Microbial involvement in U(VI) reduction has been considered to be limited to indirect effects, such as microbial metabolism providing the reduced compounds for abiological U(VI) reduction and microbial cell walls providing a surface to stimulate abiological U(VI) reduction1,12,13. We report here, however, that dissimilatory Fe(III)-reducing microorganisms can obtain energy for growth by electron transport to U(VI). This novel form of microbial metabolism can be much faster than commonly cited abiological mechanisms for U(VI) reduction. Not only do these findings expand the known potential terminal electron acceptors for microbial energy transduction, they offer a likely explanation for the deposition of uranium in aquatic sediments and aquifers, and suggest a method for biological remediation of environments contaminated with uranium.

Lovley, D. R.; Phillips, E. J. P.; Gorby, Y. A.; Landa, E. R.

1991-01-01

225

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

2012-05-17

226

ELUTION OF URANIUM FROM RESIN  

Microsoft Academic Search

A method is described for eluting uranium from anion exchange resins so ; as to decrease vanadium and iron contamination and permit recycle of the major ; portion of the eluats after recovery of the uranium. Diminution of vanadium and ; iron contamination of the major portion of the uranium is accomplished by ; treating the anion exchange resin, which

1959-01-01

227

Prospects for the uranium market  

Microsoft Academic Search

The Uranium Institute tries to find reasonably meaningful figures to identify the market for uranium. Reactor requirements are expected to rise by about 12000 tonnes by the year 2000. Actual uranium production has been lower than reactor requirements since the mid-1980s, but a high level of inventory was built up during years of excess production. United States buyers are less

1989-01-01

228

METHOD OF ELECTROPLATING ON URANIUM  

Microsoft Academic Search

This patent relates to a preparation of metallic uranium surfaces for ; receiving coatings, particularly in order to secure adherent electroplated ; coatings upon uranium metal. In accordance with the invention the uranium ; surface is pretreated by degreasing in trichloroethylene, followed by immersion ; in 25 to 50% nitric acid for several minutes, and then rinsed with running water,

E. W. Rebol; R. F. Wehrmann

1959-01-01

229

Gulf war depleted uranium risks  

Microsoft Academic Search

US and British forces used depleted uranium (DU) in armor-piercing rounds to disable enemy tanks during the Gulf and Balkan Wars. Uranium particulate is generated by DU shell impact and particulate entrained in air may be inhaled or ingested by troops and nearby civilian populations. As uranium is slightly radioactive and chemically toxic, a number of critics have asserted that

Albert C Marshall

2008-01-01

230

PROCESS OF PREPARING URANIUM CARBIDE  

DOEpatents

A process of preparing uranium monocarbide is de scribed. Uranium metal is dissolved in cadmium, zinc, cadmium-- zinc, or magnesium-- zinc alloy and a small quantity of alkali metal is added. Addition of stoichiometric amounts of carbon at 500 to 820 deg C then precipitates uranium monocarbide. (AEC)

Miller, W.E.; Stethers, H.L.; Johnson, T.R.

1964-03-24

231

PROCESS FOR RECOVERING URANIUM  

DOEpatents

A process is described for recovering uranium from deposits on stainless steel liner surfaces of calutrons. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickels copper, and iron is treated with excess of ammonium hydroxide to precipitatc the uranium, irons and chromium and convert thc nickel and copper to soluble ammonia complexions. The precipitated material is removed, dried, and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/sub 4/, UCl/sub 5/, FeCl/ sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temprrature of about 300 to400 deg C.

MacWood, G.E.; Wilder, C.D.; Altman, D.

1959-03-24

232

PROCESS FOR RECOVERYING URANIUM  

DOEpatents

A process useful in recovering uranium from deposits on stainless steel liner surfaces of calutrons is presented. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickel, copper, and iron is treated with an excess of ammonium hydroxide to precipitnte the uranium, iron, and chromium and convert the nickel and copper to soluble ammonio complexions. The precipitated material is removed, dried and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/ sub 4/, UCl/sub 5/, FeCl/sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temperature of about 500 to 400 deg C.

MacWood, G.E.; Wilder, C.D.; Altman, D.

1959-03-24

233

EXTRACTION OF URANIUM  

DOEpatents

An improved process is presented for recovering uranium from a carnotite ore. In the improved process U/sub 2/O/sub 5/ is added to the comminuted ore along with the usual amount of NaCl prior to roasting. The amount of U/sub 2/O/ sub 5/ is dependent on the amount of free calcium oxide and the uranium in the ore. Specifically, the desirable amount of U/sub 2/O/sub 5/ is 3.2% for each 1% of CaO, and 5 to 6% for each 1% of uranium. The mixture is roasted at about 1560 deg C for about 30 min and then leached with a 3 to 9% aqueous solution of sodium carbonate.

Kesler, R.D.; Rabb, D.D.

1959-07-28

234

Uranium Transport Modeling  

SciTech Connect

Uranium contamination is prevalent at many of the U.S. DOE facilities and at several civilian sites that have supported the nuclear fuel cycle. The potential off-site mobility of uranium depends on the partitioning of uranium between aqueous and solid (soil and sediment) phases. Hexavalent U (as uranyl, UO{sub 2}{sup 2+}) is relatively mobile, forming strong complexes with ubiquitous carbonate ion which renders it appreciably soluble even under mild reducing conditions. In the presence of carbonate, partition of uranyl to ferri-hydrate and select other mineral phases is usually maximum in the near-neutral pH range {approx} 5-8. The surface complexation reaction of uranyl with iron-containing minerals has been used as one means to model subsurface migration, used in conjunction with information on the site water chemistry and hydrology. Partitioning of uranium is often studied by short-term batch 'equilibrium' or long-term soil column testing ; MCLinc has performed both of these methodologies, with selection of method depending upon the requirements of the client or regulatory authority. Speciation of uranium in soil may be determined directly by instrumental techniques (e.g., x-ray photoelectron spectroscopy, XPS; x-ray diffraction, XRD; etc.) or by inference drawn from operational estimates. Often, the technique of choice for evaluating low-level radionuclide partitioning in soils and sediments is the sequential extraction approach. This methodology applies operationally-defined chemical treatments to selectively dissolve specific classes of macro-scale soil or sediment components. These methods recognize that total soil metal inventory is of limited use in understanding bioavailability or metal mobility, and that it is useful to estimate the amount of metal present in different solid-phase forms. Despite some drawbacks, the sequential extraction method can provide a valuable tool to distinguish among trace element fractions of different solubility related to mineral phases. Four case studies are presented: Water and Soil Characterization, Subsurface Stabilization of Uranium and other Toxic Metals, Reductive Precipitation (in situ bioremediation) of Uranium, and Physical Transport of Particle-bound Uranium by Erosion.

Bostick, William D. [Materials and Chemistry Laboratory, Inc. (MCLinc), East Tennessee Technology Park, Building K-1006, 2010 Highway 58, Suite 1000, Oak Ridge, Tennessee 37830-1702 (United States)

2008-01-15

235

PROCESS OF RECOVERING URANIUM  

DOEpatents

An improved precipitation method is described for the recovery of uranium from aqueous solutions. After removal of all but small amounts of Ni or Cu, and after complexing any iron present, the uranium is separated as the peroxide by adding H/sub 2/O/sub 2/. The improvement lies in the fact that the addition of H/sub 2/O/sub 2/ and consequent precipitation are carried out at a temperature below the freezing; point of the solution, so that minute crystals of solvent are present as seed crystals for the precipitation.

Price, T.D.; Jeung, N.M.

1958-06-17

236

Oscillatory extraction of uranium  

SciTech Connect

The kinetics of U and Ce extraction by tri-n-butyl-phosphate (TBP) and the redox potential behavior in the aqueous phase have been investigated in an oscillatory extraction system. The extraction has been followed continuously by UV-visible spectroscopy, potentiometry, and radioactive counting methods. Data collected showed the changes of Ce{sup 4+} and UO{sub 2}{sup 2+} concentrations in organic and aqueous phases with time. Uranium actively responded to the redox potential fluctuations. The uranium distribution coefficient changed repeatedly and was out-of-phase with Ce(IV) fluctuations.

Afonin, M.A.; Romanovski, V.V. [Saint Petersburg Inst. of Tech. (Russian Federation); Scherbakov, V.A. [Khlopin Radium Inst., Saint Petersburg (Russian Federation)

1998-08-01

237

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); Kollie, Thomas G. (Oak Ridge, TN); Bell, Richard T. (Knoxville, TN)

1983-01-01

238

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

239

PRODUCTION OF URANIUM TUBING  

DOEpatents

The manufacture of thin-walled uranium tubing by the hot-piercing techique is described. Uranium billets are preheated to a temperature above 780 d C. The heated billet is fed to a station where it is engaged on its external surface by three convex-surfaced rotating rollers which are set at an angle to the axis of the billet to produce a surface friction force in one direction to force the billet over a piercing mandrel. While being formed around the mandrel and before losing the desired shape, the tube thus formed is cooled by a water spray.

Creutz, E.C.

1958-04-15

240

High loading uranium fuel plate  

DOEpatents

Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry R. (Palos Heights, IL)

1990-01-01

241

Uranium Reduction by Clostridia  

SciTech Connect

The FRC groundwater and sediment contain significant concentrations of U and Tc and are dominated by low pH, and high nitrate and Al concentrations where dissimilatory metal reducing bacterial activity may be limited. The presence of Clostridia in Area 3 at the FRC site has been confirmed and their ability to reduce uranium under site conditions will be determined. Although the phenomenon of uranium reduction by Clostridia has been firmly established, the molecular mechanisms underlying such a reaction are not very clear. The authors are exploring the hypothesis that U(VI) reduction occurs through hydrogenases and other enzymes (Matin and Francis). Fundamental knowledge of metal reduction using Clostridia will allow us to exploit naturally occurring processes to attenuate radionuclide and metal contaminants in situ in the subsurface. The outline for this report are as follows: (1) Growth of Clostridium sp. under normal culture conditions; (2) Fate of metals and radionuclides in the presence of Clostridia; (3) Bioreduction of uranium associated with nitrate, citrate, and lepidocrocite; and (4) Utilization of Clostridium sp. for immobilization of uranium at the FRC Area 3 site.

Francis, A.J.; Dodge, Cleveland J.; Gillow, Jeffrey B.

2006-04-05

242

Worldwide developments in uranium  

Microsoft Academic Search

World uranium production will continue to change in most major producing nations. Canadian production will increase and will be increasingly dominated by western producers as eastern Canadian high-cost production declines. Australian production will increase as major projects come into operation before 2000. US production will stabilize through the end of the century. South African production will be dependent upon the

Hoellen

1987-01-01

243

URANIUM SOLVENT EXTRACTION PROCESS  

DOEpatents

A method is given for extracting uranium values from ores of high phosphate content consisting of dissolving them in aqueous nitric acid, adjusting the concentration of the aqueous solution to about 2 M with respect to nitric acid, and then contacting it with diethyl ether which has previously been made 1 M with respect to nitric acid.

Harrington, C.D.

1959-09-01

244

Uranium hexafluoride bibliography  

Microsoft Academic Search

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

Burnham

1988-01-01

245

Separation of uranium isotopes  

SciTech Connect

Methods and apparatus for separation of uranium isotopes by selective isotopic excitation of photochemically reactive uranyl salt source material at cryogenic temperatures, followed by chemical separation of selectively photochemically reduced U/sup +4/ thereby produced from remaining uranyl source material.

Porter, J.T. II

1984-03-27

246

Self-diffusion of oxygen in superstoichiomertric uranium dioxide in the range of the superion phase transition  

NASA Astrophysics Data System (ADS)

The self-diffusion of oxygen in the superion transition range (1300-3000 K) of superstoichiometric uranium dioxide UO2 + x is studied by the method of molecular dynamics using the pair interaction potential recovered from data for the thermal expansion of the UO2 lattice. It is shown that three portions can be distinguished in the temperature dependence of the coefficient of oxygen self-diffusion in UO2 + x , ln D = f(1/ T), for all the compositions studied ( x = 0, 0.008, and 0.030). These portions, each being described by the Arrhenius relationship, correspond to the crystalline, transition, and superion states of UO2 + x . At low temperatures (1300-1820 K), the activation energies of oxygen diffusion for the above compositions are, respectively, 2.66 0.44, 1.33 0.10, and 1.00 0.09 eV. At the beginning of the transition region, these activation energies rise to 3.40 0.11, 2.24 0.10, and 1.66 0.60 eV. In the superion state, the activation energy of oxygen diffusion for all the compositions is the same, 1.25 0.15 eV, within the error limit. As the oxygen content in UO2 + x grows, the phase transition temperature decreases considerably and may reach 1600 K at x = 0.2. Comparison with experimental data for the low-temperature oxygen diffusion coefficient and with the data of UO2 simulation using graphic processors shows good agreement of the results. By comparing the concentration dependences of the oxygen diffusion coefficient that are obtained by magnetic dynamics simulation with experimental data, it is shown that quantitative calculation of these dependences in the case of UO2 + x can be carried out only for compositions with x < 0.03 if the given type of potential is used.

Kupryazhkin, A. Ya.; Svetlichnyi, D. G.; Zhiganov, A. N.

2011-02-01

247

Uranium from seawater  

SciTech Connect

A novel process for recovering uranium from seawater is proposed and some of the critical technical parameters are evaluated. The process, in summary, consists of two different options for contacting adsorbant pellets with seawater without pumping the seawater. It is expected that this will reduce the mass handling requirements, compared to pumped seawater systems, by a factor of approximately 10/sup 5/, which should also result in a large reduction in initial capital investment. Activated carbon, possibly in combination with a small amount of dissolved titanium hydroxide, is expected to be the preferred adsorbant material instead of the commonly assumed titanium hydroxide alone. The activated carbon, after exposure to seawater, can be stripped of uranium with an appropriate eluant (probably an acid) or can be burned for its heating value (possible in a power plant) leaving the uranium further enriched in its ash. The uranium, representing about 1% of the ash, is then a rich ore and would be recovered in a conventional manner. Experimental results have indicated that activated carbon, acting alone, is not adequately effective in adsorbing the uranium from seawater. We measured partition coefficients (concentration ratios) of approximately 10/sup 3/ in seawater instead of the reported values of 10/sup 5/. However, preliminary tests carried out in fresh water show considerable promise for an extraction system that uses a combination of dissolved titanium hydroxide (in minute amounts) which forms an insoluble compound with the uranyl ion, and the insoluble compound then being sorbed out on activated carbon. Such a system showed partition coefficients in excess of 10/sup 5/ in fresh water. However, the system was not tested in seawater.

Gregg, D.; Folkendt, M.

1982-09-21

248

Elevated urine uranium excretion by soldiers with retained uranium shrapnel.  

PubMed

The use of depleted uranium in munitions has given rise to a new exposure route for this chemically and radioactively hazardous metal. A cohort of U.S. soldiers wounded while on or in vehicles struck by depleted uranium penetrators during the Persian Gulf War was identified. Thirty-three members of this cohort were clinically evaluated, with particular attention to renal abnormalities, approximately 3 y after their injury. The presence of retained shrapnel was identified by x ray, and urine uranium concentrations were measured on two occasions. The absorption of uranium from embedded shrapnel was strongly suggested by measurements of urine uranium excretion at two time intervals: one in 1993/1994 and one in 1995. Mean urine uranium excretion was significantly higher in soldiers with retained shrapnel compared to those without shrapnel at both time points (4.47 vs. 0.03 microg g(-1) creatinine in 1993/1994 and 6.40 vs. 0.01 microg g(-1) creatinine in 1995, respectively). Urine uranium concentrations measured in 1995 were consistent with those measured in 1994/1993, with a correlation coefficient of 0.9. Spot urine measurements of uranium excretion were also well correlated with 24-h urine collections (r = 0.95), indicating that spot urine samples can be reliably used to monitor depleted uranium excretion in the surveillance program for this cohort of soldiers. The presence of uranium in the urine can be used to determine the rate at which embedded depleted uranium fragments are releasing biologically active uranium ions. No evidence of a relationship between urine uranium excretion and renal function could be demonstrated. Evaluation of this cohort continues. PMID:10524504

Hooper, F J; Squibb, K S; Siegel, E L; McPhaul, K; Keogh, J P

1999-11-01

249

Iron EDTA chelate catalyzed oxidation of uranium  

Microsoft Academic Search

Uranium ore deposits which contain uranium in the relatively insoluble tetravalent state are readily selectively leached in situ to recover relatively pure uranium compounds, by: (A) passing through the ore deposit a relatively dilute aqueous leach solution of ammonium bicarbonate, ferric ammonium ethylenediaminetetraacetic acid (EDTA), and a source of oxygen, the leach solution converting the tetravalent uranium to hexavalent uranium

J. F. Jackovitz; A. J. Panson; E. A. Pantier

1981-01-01

250

Enzymatic Reduction and Precipitation of Uranium.  

National Technical Information Service (NTIS)

A method is presented for removing uranium from uranium contaminated water that involves adding uranium reducing microorganisms and an electron donor to uranium contaminated water to reduce U(VI) in the uranium contaminated water to U(IV), which in turn f...

D. R. Lovley

1992-01-01

251

Method of separating molybdenum from uranium  

Microsoft Academic Search

A method is disclosed for separating uranium from molybdenum in an aqueous solution. The pH of the solution is lowered to about 1 to about 4 using an inorganic acid such as hydrochloric acid. The carbon dioxide is then removed from the solution which can be done by aeration. The pH of the solution is raised to about 9 in

T. J. Crosssley; T. P. Zinge

1983-01-01

252

Uranium speciation in waters of different uranium mining areas  

Microsoft Academic Search

The uranium speciation in three uranium mining-related waters from Saxony\\/Germany was experimentally determined by laser spectroscopy. The obtained species distributions were successfully compared with modeling predictions for the different U(VI) species that were calculated with the modeling software EQ3\\/6 using the NEA data base [1, 2]. Three different solution complexes characterize the uranium speciation in the investigated waters:1. In carbonate-

G Bernhard; G Geipel; V Brendler; H Nitsche

1998-01-01

253

Method of preparing uranium nitride or uranium carbonitride bodies  

DOEpatents

Sintered uranium nitride or uranium carbonitride bodies having a controlled final carbon-to-uranium ratio are prepared, in an essentially continuous process, from U.sub.3 O.sub.8 and carbon by varying the weight ratio of carbon to U.sub.3 O.sub.8 in the feed mixture, which is compressed into a green body and sintered in a continuous heating process under various controlled atmospheric conditions to prepare the sintered bodies.

Wilhelm, Harley A. (Ames, IA); McClusky, James K. (Valparaiso, IN)

1976-04-27

254

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

255

PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM  

Microsoft Academic Search

Processes are described for preparing plutonium, particularly processes ; of separating plutonium from uranium and fission products in neutron-irradiated ; uraniumcontaining matter. Specifically, plutonium solutions containing uranium, ; fission products and other impurities are contacted with reducing agents such as ; sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ; ferrous ion whereby the plutoninm is reduced to

R. E. Connick; J. W. Gofman; G. C. Pimentel

1959-01-01

256

Method for fabricating uranium foils and uranium alloy foils  

SciTech Connect

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

257

RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS  

DOEpatents

An improvement was made in a process of recovering uranium from a uranium-zirconium composition which was hydrochlorinated with gsseous hydrogen chloride at a temperature of from 350 to 800 deg C resulting in volatilization of the zirconium, as zirconium tetrachloride, and the formation of a uranium containing nitric acid insoluble residue. The improvement consists of reacting the nitric acid insoluble hydrochlorination residue with gaseous carbon tetrachloride at a temperature in the range 550 to 600 deg C, and thereafter recovering the resulting uranium chloride vapors. (AEC)

Gens, T.A.

1962-07-10

258

Extraction of impurities of rare-earth elements from uranium dioxide using bromine trifluoride for their preconcentration and analytical determination  

Microsoft Academic Search

The behavior of impurities of rare-earth elements in the fluorination of UO2 with bromine trifluoride is studied by the radioactive tracer method using152Eu radionuclide. It is demonstrated that uranium is completely removed as hexafluoride, whereas impurities of rare-earth elements\\u000a quantitatively remain in the crucible because of the nonvolatility of their fluorides. Based on this fact, the concentrations\\u000a of rare-earth elements

V. N. Mitkin; B. M. Shavinskii; A. I. Kamelin

2000-01-01

259

Application of bromine trifluoride for pre-concentration and determination of rare-earth elements in fuel uranium dioxide  

Microsoft Academic Search

Radioactive indicator's (152Eu) method was used to study the behavior of rare-earth element (REE) micro-impurities at fluorination of fuel UO2 with bromine trifluoride. The proposed process is very simple and carried out under a blanket layer of Freon-113 in the glassy carbon (vitreous) crucibles.It was shown that uranium matrix completely removes from reaction sphere in the form of UF6 and

V. N. Mitkin; B. M. Shavinsky

2009-01-01

260

METHOD OF PRODUCING URANIUM  

DOEpatents

A modified process is described for the production of uranium metal by means of a bomb reduction of UF/sub 4/. Difficulty is sometimes experienced in obtaining complete separation of the uranium from the slag when the process is carried out on a snnall scale, i.e., for the production of 10 grams of U or less. Complete separation may be obtained by incorporating in the reaction mixture a quantity of MnCl/sub 2/, so that this compound is reduced along with the UF/sub 4/ . As a result a U--Mn alloy is formed which has a melting point lower than that of pure U, and consequently the metal remains molten for a longer period allowing more complete separation from the slag.

Foster, L.S.; Magel, T.T.

1958-05-13

261

FORMATION OF URANIUM PRECIPITATES  

DOEpatents

A method is described for precipitation of uranium peroxide from uranium- containing solutions so as to obtain larger aggregates which facilitates washings decantations filtrations centrifugations and the like. The desired larger aggregate form is obtained by maintaining the pH of the solution in the approximate range of 1 to 3 and the temperature at about 25 deg C or below while carrytng out the precipitation. Then prior to removal of the precipitate a surface active sulfonated bicarboxyacids such as di-octyl sodium sulfo-succinates is incorporated in an anount of the order of 0.01 to 0.05 percent by weights and the slurry is allowed to ripen for about one-half hour at a temperatare below 10 deg C.

Googin, J.M. Jr.

1959-03-17

262

PROCESS FOR PRODUCING URANIUM TETRAFLUORIDE  

DOEpatents

>This patent relates to improvements in the method for producing uranium tetrafluoride by treating an aqueous solutlon of a uranyl salt at an elevated temperature with a reducing agent effective in acld solutlon in the presence of hydrofluoric acid. Uranium tetrafluoride produced this way frequentiy contains impurities in the raw material serving as the source of uranium. Uranium tetrafluoride much less contaminated with impurities than when prepared by the above method can be prepared from materials containing such impurities by first adding a small proportion of reducing agent so as to cause a small fraction, for example 1 to 5% of the uranium tetrafluoride to be precipitated, rejecting such precipitate, and then precipitating and recovering the remainder of the uranium tetrafluoride.

Harvey, B.G.

1954-09-14

263

Treatment of effluents from uranium oxide production.  

PubMed

The nuclear fuel cycle comprises a series of industrial processes which involve the production of electricity from uranium in nuclear power reactors. In Brazil the conversion of uranium hexafluoride (UF6) into uranium dioxide (UO2) takes place in Resende (RJ) at the Nuclear Fuel Factory (FCN). The process generates liquid effluents with significant concentrations of uranium, which might be treated before being discharged into the environment. This study investigates the recovery of uranium from three distinct liquid effluents: one with a high carbonate content and the other with an elevated fluoride concentration. This paper also presents a study on carbonate removal from an effluent that consists of a water-methanol solution generated during the filtration of the yellow cake (ammonium uranyl tricarbonate). The results showed that: (1) the uranium from the carbonated solution can be recovered through the ion exchange technique using the strong base anionic resin IRA 910-U, as the carbonate has been removed as CO2 after heating; (2) the most suitable technique to recover uranium from the fluoride solution is its precipitation as (NH4)2UO4F2 (ammonium fluorouranate peroxide), (3) the solution free of carbonate can be added to the fluoride solution and the uranium from the final solution can be recovered by precipitation as ammonium fluorouranate peroxide as well; (4) the carbonate from the water-methanol solution can be recovered as calcium carbonate through the addition of calcium chloride, or it can be recovered as ammonium sulphate through the addition of sulphuric acid. The ammonium sulphate product can be used as a fertilizer. PMID:21473275

Ladeira, A C Q; Gonalves, J S; Morais, C A

2011-01-01

264

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

265

WELDED JACKETED URANIUM BODY  

DOEpatents

A fuel element is presented for a neutronic reactor and is comprised of a uranium body, a non-fissionable jacket surrounding sald body, thu jacket including a portion sealed by a weld, and an inclusion in said sealed jacket at said weld of a fiux having a low neutron capture cross-section. The flux is provided by combining chlorine gas and hydrogen in the intense heat of-the arc, in a "Heliarc" welding muthod, to form dry hydrochloric acid gas.

Gurinsky, D.H.

1958-08-26

266

64 FR 42728 - International Uranium (USA) Corporation  

Federal Register 2010, 2011, 2012, 2013

...Number 40-9048] International Uranium (USA) Corporation AGENCY: Nuclear Regulatory...a request from International Uranium (USA) Corporation that the NRC terminate all...a predecessor of International Uranium (USA) Corporation. The NRC received a...

1999-08-05

267

Demonstration of Jackhammer Incorporating Depleted Uranium.  

National Technical Information Service (NTIS)

The United States government currently has an abundance of depleted uranium (DU). This surplus of about 1 billion pounds is the result of an enrichment process using gaseous diffusion to produce enriched and depleted uranium. The enriched uranium has been...

L. E. Fishcer R. W. Hoard D. L. Carter

2000-01-01

268

77 FR 12880 - Uranium From Russia  

Federal Register 2010, 2011, 2012, 2013

...731-TA-539-C (Third Review)] Uranium From Russia Determination On the basis...termination of the suspended investigation on uranium from Russia would be likely to lead to...Publication 4307 (February 2012), entitled Uranium from Russia: Investigation No....

2012-03-02

269

Determination of Uranium in Urine by Fluorometry.  

National Technical Information Service (NTIS)

The report describes fluorometric determination of traces of uranium in the urine of mine workers and persons handling uranium. After preliminary treatment uranium is extracted by solvent extraction with TBP:MIBK mixtures. An aliquot of the extracted solu...

M. Afsar A. Aziz M. A. Mubarak

1978-01-01

270

NEWS AND INFORMATION: Depleted uranium  

Microsoft Academic Search

The potential health effects arising from exposure to depleted uranium have been much in the news of late. Naturally occurring uranium contains the radioisotopes 238U (which dominates, at a current molar proportion of 99.3%), 235U and a small amount of 234U. Depleted uranium has an isotopic concentration of 235U that is below the 0.7% found naturally. This is either because

Richard Wakeford

2001-01-01

271

Uranium resources in New Mexico  

Microsoft Academic Search

For nearly three decades (1951-1980), the Grants uranium district in northwestern New Mexico produced more uranium than any other district in the world. The most important host rocks containing economic uranium deposits in New Mexico are sandstones within the Jurassic Morrison Formation. Approximately 334,506,000 lb of UO were produced from this unit from 1948 through 1987, accounting for 38% of

V. T. McLemore; W. L. Chenoweth

1989-01-01

272

METHOD OF JACKETING URANIUM BODIES  

DOEpatents

An improved process is presented for providing uranium slugs with thin walled aluminum jackets. Since aluminum has a slightiy higher coefficient of thermal expansion than does uraaium, both uranium slugs and aluminum cans are heated to an elevated temperature of about 180 C, and the slug are inserted in the cans at that temperature. During the subsequent cooling of the assembly, the aluminum contracts more than does the uranium and a tight shrink fit is thus assured.

Maloney, J.O.; Haines, E.B.; Tepe, J.B.

1958-08-26

273

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

274

Two stage selective oxidative leach method to separately recover uranium and refractory uranium-mineral complexes  

SciTech Connect

The present invention relates to a process for the recovery of uranium and other minerals from uranium ore where at least part of the uranium is present as refractory uranium-mineral complexes, comprising subjecting the uranium ore to mild oxidative carbonate leach fluid to dissolve and remove readily soluble uranium minerals, subsequently subjecting the uranium ore to an oxidative chemically severe leaching system to dissolve and remove the refractory uranium-mineral complexes, and separating and recovering the uranium and other mineral species in the leachate fluids. The process may be applied to in-situ uranium leaching operations or to surface leaching operations.

Tsui, T.F.

1984-03-20

275

Geological classification of uranium deposits  

SciTech Connect

The worst of times for the uranium producer may be over and a new episode in the tale of uranium is starting to unfold. In this next episode, trade restrictions, civilian inventories, and even HEU are drifting slowly backstage. With the changing scene-uranium prices having finally crossed the $13 per pound U{sub 3}O{sub 8} threshold, and with expectations of continued strengthening-the uranium producer is once again assuming the role protagonist. The price gap that was opened with restrictions on CIS-origin uranium is now closing as this lower-priced supply appears to be scarce. Even matched sales may lose their appeal to both producer and utility. HEU and other inventories, once thought to be able to flood the market, are now turning out to be mostly pomp, with little circumstance. Meanwhile, industry participants, especially utilities, sit on the edge of their seats, already wondering if a soliloquy by the uranium producer can keep their undivided attention. The question in 1996 and through the turn of the century will be whether uranium producers are capable of mining enough uranium to satisfy utility requirements. If so, at what prices? And for how long? Where will 150 million pounds per year of uranium come from? Producers are already gearing up exploration crews in almost every continent in an effort to increase minable reserves. Some are even exploring in new areas, hopeful that lower-cost reserves will be found in addition to their discovered deposits.

NONE

1996-02-01

276

ELECTROLYTIC PRODUCTION OF URANIUM TETRAFLUORIDE  

DOEpatents

This patent relates to electrolytic methods for the production of uranium tetrafluoride. According to the present invention a process for the production of uranium tetrafluoride comprises submitting to electrolysis an aqueous solution of uranyl fluoride containing free hydrofluoric acid. Advantageously the aqueous solution of uranyl fluoride is obtained by dissolving uranium hexafluoride in water. On electrolysis, the uranyl ions are reduced to uranous tons at the cathode and immediately combine with the fluoride ions in solution to form the insoluble uranium tetrafluoride which is precipitated.

Lofthouse, E.

1954-08-31

277

THERMAL DECOMPOSITION OF URANIUM COMPOUNDS  

DOEpatents

A method is presented of preparing uranium metal of high purity consisting contacting impure U metal with halogen vapor at between 450 and 550 C to form uranium halide vapor, contacting the uranium halide vapor in the presence of H/sub 2/ with a refractory surface at about 1400 C to thermally decompose the uranium halides and deposit molten U on the refractory surface and collecting the molten U dripping from the surface. The entire operation is carried on at a sub-atmospheric pressure of below 1 mm mercury.

Magel, T.T.; Brewer, L.

1959-02-10

278

The Toxicity of Depleted Uranium  

PubMed Central

Depleted uranium (DU) is an emerging environmental pollutant that is introduced into the environment primarily by military activity. While depleted uranium is less radioactive than natural uranium, it still retains all the chemical toxicity associated with the original element. In large doses the kidney is the target organ for the acute chemical toxicity of this metal, producing potentially lethal tubular necrosis. In contrast, chronic low dose exposure to depleted uranium may not produce a clear and defined set of symptoms. Chronic low-dose, or subacute, exposure to depleted uranium alters the appearance of milestones in developing organisms. Adult animals that were exposed to depleted uranium during development display persistent alterations in behavior, even after cessation of depleted uranium exposure. Adult animals exposed to depleted uranium demonstrate altered behaviors and a variety of alterations to brain chemistry. Despite its reduced level of radioactivity evidence continues to accumulate that depleted uranium, if ingested, may pose a radiologic hazard. The current state of knowledge concerning DU is discussed.

Briner, Wayne

2010-01-01

279

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

280

SEPARATION OF THORIUM FROM URANIUM  

DOEpatents

A description is given for the separation of thorium from uranium by forming an aqueous acidic solution containing ionic species of thorium, uranyl uranium, and hydroxylamine, flowing the solution through a column containing the phenol-formaldehyde type cation exchange resin to selectively adsorb substantially all the thorium values and a portion of the uranium values, flowing a dilute solution of hydrochloric acid through the column to desorb the uranium values, and then flowing a dilute aqueous acidic solution containing an ion, such as bisulfate, which has a complexing effect upon thortum through the column to desorb substantially all of the thorium.

Bane, R.W.

1959-09-01

281

Production and analysis of ultradispersed uranium oxide powders  

NASA Astrophysics Data System (ADS)

Spectroscopic studies are made of the laser plasma formed near the surface of a porous body containing nanoquantities of uranium compounds which is irradiated by two successive laser pulses. The feasibility of using laser chemical methods for obtaining nanoclusters of uranium oxide particles in the volume of a porous body and the simultaneous possibility of determining the uranium content with good sensitivity are demonstrated. The thermochemical and spectral characteristics of the analogs of their compounds with chlorine are determined and studied. The possibility of producing uranium dioxides under ordinary conditions and their analysis in the reaction products is demonstrated.

Zajogin, A. P.; Komyak, A. I.; Umreiko, D. S.; Umreiko, S. D.

2010-05-01

282

METHOD FOR RECOVERING URANIUM FROM OILS  

DOEpatents

A method is presented for recovering uranium from hydrocarbon oils, wherein the uranium is principally present as UF/sub 4/. According to the invention, substantially complete removal of the uranium from the hydrocarbon oil may be effected by intimately mixing one part of acetone to about 2 to 12 parts of the hydrocarbon oil containing uranium and separating the resulting cake of uranium from the resulting mixture. The uranium in the cake may be readily recovered by burning to the oxide.

Gooch, L.H.

1959-07-14

283

Method for fluorination of uranium oxide  

SciTech Connect

This patent describes an improved method for the conversion of uranium oxide to uranium hexafluoride, which comprises introducing the oxide, together with a small amount of fluorine-reactive substance, selected from the group consisting of alkali chlorides, silicon dioxide, silicic acid, ferric oxide, and bromine, into a constant volume reaction zone, charging sufficient fluorine into the zone at a temperature below approximately 0/sup 0/C to provide an initial pressure of at least approximately 600 lbs/sq.in. at the ambient atmospheric temperature, and then permitting the temperature to rise in the reaction zone until reaction ensues.

Petit, G.S.

1987-11-03

284

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

285

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

286

Conversion of depleted uranium hexafluoride to a solid uranium compound  

DOEpatents

A process for converting UF.sub.6 to a solid uranium compound such as UO.sub.2 and CaF. The UF.sub.6 vapor form is contacted with an aqueous solution of NH.sub.4 OH at a pH greater than 7 to precipitate at least some solid uranium values as a solid leaving an aqueous solution containing NH.sub.4 OH and NH.sub.4 F and remaining uranium values. The solid uranium values are separated from the aqueous solution of NH.sub.4 OH and NH.sub.4 F and remaining uranium values which is then diluted with additional water precipitating more uranium values as a solid leaving trace quantities of uranium in a dilute aqueous solution. The dilute aqueous solution is contacted with an ion-exchange resin to remove substantially all the uranium values from the dilute aqueous solution. The dilute solution being contacted with Ca(OH).sub.2 to precipitate CaF.sub.2 leaving dilute NH.sub.4 OH.

Rothman, Alan B. (Willowbrook, IL); Graczyk, Donald G. (Lemont, IL); Essling, Alice M. (Elmhurst, IL); Horwitz, E. Philip (Naperville, IL)

2001-01-01

287

Decay Heat Calculations for PWR and BWR Assemblies Fueled with Uranium and Plutonium Mixed Oxide Fuel using SCALE  

Microsoft Academic Search

In currently operating commercial nuclear power plants (NPP), there are two main types of nuclear fuel, low enriched uranium (LEU) fuel, and mixed-oxide uranium-plutonium (MOX) fuel. The LEU fuel is made of pure uranium dioxide (UO or UOX) and has been the fuel of choice in commercial light water reactors (LWRs) for a number of years. Naturally occurring uranium contains

Brian J Ade; Ian C Gauld

2011-01-01

288

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

289

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.

290

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

291

METHOD OF SEPARATING URANIUM SUSPENSIONS  

DOEpatents

A process is presented for separating colloidally dissed uranium oxides from the heavy water medium in upwhich they are contained. The method consists in treating such dispersions with hydrogen peroxide, thereby converting the uranium to non-colloidal UO/sub 4/, and separating the UO/sub 4/ sfter its rapid settling.

Wigner, E.P.; McAdams, W.A.

1958-08-26

292

Separation Equipment for Uranium Isotopes.  

National Technical Information Service (NTIS)

Separation equipment for uranium isotopes consists of a first laser using a rare gas or a rare gas compound as its active substance; a second, tunable laser which is subjected to photoexcitation by the first laser; a device for generating uranium vapor; a...

M. Yamamoto

1977-01-01

293

Components of uranium enrichment plant  

Microsoft Academic Search

A cross-linked product of ethylene-hexafluoropropylene copolymer is a good elastic material and has excellent resistance to attack by uranium hexafluoride even at a high temperature. Components made of said copolymer exhibit surprisingly long life, when used in a uranium enrichment plant.

M. Ito; S. Machi; G. Okamoto; K. Shirayama

1981-01-01

294

Uranium mining in East Germany (\\  

Microsoft Academic Search

Underground uranium mining was performed in East Germany after World War II on a large scale. Working conditions were very poor during the post-war years from approx. 1946 to 1955. During later years mining conditions improved. In 1990, uranium production was generally stopped as a consequence of German reunification. A company-based health care system commenced in the early years with

G. J. Enderle; K. Friedrich

1999-01-01

295

The gamma Rays of Uranium  

Microsoft Academic Search

OUR knowledge of the gamma rays of uranium has until now been confined to their discovery by Rutherford (Phys. Zeit., 1902, 517) and to the observations of Eve (ibid., 1907, 185). The latter directed attention to their extraordinary feebleness and to their relatively low penetrating power. Eve found that uranium gives out only about one-tenth as much gamma radiation as

Frederick Soddy; Alexander S. Russell

1909-01-01

296

Estudo dos parametros de processo da reducao do tricarbonato de amonio e uranilo a dioxido de uranio em forno de leito fluidizado. (Study of process parameters for reducing ammonium uranyl carbonate to uranium dioxide in fluidized bed furnace).  

National Technical Information Service (NTIS)

This work consists of studying the process parameters of AUC (ammonium uranyl carbonate) to UO(sub 2) (uranium dioxide) reduction, with good physical and chemical characteristics, in fluidized bed. Initially, it was performed UO(sub 2) cold fluidization e...

C. B. Leitao Junior

1992-01-01

297

Uranium hexafluoride subsampling system  

SciTech Connect

A uranium hexafluoride sampling system is currently being used at the Oak Ridge Gaseous Diffusion Plant (ORGDP) which (1) is low cost to fabricate, (2) is easy to maintain, (3) is convenient to operate, and (4) reduces risks associated with the use of high-heat sources (open flame torches). The new systems have been in use at the ORGDP for more than 15 months without substantial maintenance or operational problems. Use of the systems have not influenced analytical results and thus have the same quality of sample integrity as was inherent in the former systems. 2 refs., 5 figs.

Hall, H.J.; Hedge, W.D.; Reid, D.D.

1985-07-01

298

Uranium hexafluoride carrier  

US Patent & Trademark Office Database

A container complying with ANSI.RTM. N14.1 for containing uranium hexafluoride (UF.sub.6) which minimizes entrapment of contaminants, thereby increasing the decontaminability of the container. The container includes a cylindrical shell welded to two cylinder heads wherein the weld inside the container provides a smooth transition between the heads and the shell while complying with ANSI.RTM. N14.1. The heads and the shell each have an annular land. A plasma weld fully penetrates the opposing lands to join the heads and the shell. No backup bar is used during the welding process.

Rasel; Gerald E. (Columbiana, OH); Eckert; Alan (Leetonia, OH); Rummel; Trevor M. (Leetonia, OH)

1998-07-07

299

Electrocrystallization of uranium oxides from molten salt media with adjustable oxygen coefficient value  

Microsoft Academic Search

In order to determine the conditions necessary to produce uranium oxides with the preset oxygen coefficient value by electrolyzing salt electrolytes, we have investigated the chemical and electrochemical behavior of the oxychloride uranium compounds with various valancies in molten alkali chlorides. The electrochemical production conditions for uranium dioxide of the pre-stoichiometric composition were determined.

V. V. Smolenski; A. L. Bovet; V. E. Komarov

1993-01-01

300

Converting {sup 99}Mo production from high- to low-enriched uranium  

SciTech Connect

This paper discusses efforts towards LEU substitution in two HEU targets. One type is the Cintichem target, a closed cylinder with a thin coating of uranium dioxide electroplated ion the inside wall. To successfully increase the amount of uranium per target, we are developing a target that uses LEU metal foil. Uranium surface preparation is discussed.

Vandegrift, G.F.; Conner, C.J.; Sedlet, J.; Wygmans, D.G.

1997-09-01

301

Method and combustion reactor for converting uranium hexafluoride gas to an oxide of uranium  

Microsoft Academic Search

This patent describes a method for converting uranium hexafluoride to uranium oxide in a gaseous reaction medium, comprising the steps of: (a) supplying gases individually comprising uranium hexafluoride, oxygen and hydrogen, and mixing same; (b) feeding the mixed gases as a combined jet stream into a reactor zone wherein the uranium hexafluoride is converted to an oxide of uranium; (c)

D. G. Linz; R. K. Jr. Grier; J. A. Wetzel; A. G. Dada; J. D. Connolly

1987-01-01

302

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

Microsoft Academic Search

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

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

2008-01-01

303

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

304

Uranium mill tailings stabilization  

SciTech Connect

Uranium mill tailings pose a potential radiation health hazard to the public. Therefore, stabilization or disposal of these tailings in a safe and environmentally sound way is needed to minimize radon exhalation and other environmental hazards. One of the most promising concepts for stabilizing U tailings is the use of asphalt emulsion to contain radon and other hazardous materials within uranium tailings. This approach is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admixture seal (2.5 to 12.7 cm thick) containing about 18 wt % residual asphalt. A field test was carried out in June 1979 at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 15.2-cm (6-in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer was used to apply the admix. Following compaction, a spray coat seal was applied over the admix as the final step in construction of a radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration.

Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

1980-02-01

305

Process for removing carbon from uranium  

DOEpatents

Carbon contamination is removed from uranium and uranium alloys by heating in inert atmosphere to 700.degree.-1900.degree.C in effective contact with yttrium to cause carbon in the uranium to react with the yttrium. The yttrium is either in direct contact with the contaminated uranium or in indirect contact by means of an intermediate transport medium.

Powell, George L. (Oak Ridge, TN); Holcombe, Jr., Cressie E. (Knoxville, TN)

1976-01-01

306

Uranium accumulation by Pseudomonas sp. EPS5028  

Microsoft Academic Search

Pseudomonas sp. EPS-5028 was examined for the ability to accumulate uranium from solutions. The uptake of uranium by this microorganism is very rapid and is affected by pH but not by temperature, metabolic inhibitors, culture time and the presence of various cations and anions. The amount of uranium absorbed by the cells increased as the uranium concentration of the solution

Ana M. Marqus; Xavier Roca; M. Dolores Simon-Pujol; M. Carmen Fuste; Francisco Congregado

1991-01-01

307

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 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...

2013-07-01

308

The recrystallization of cold-rolled uranium  

Microsoft Academic Search

This paper gives the results of investigations into the effect of rolling and annealing in the a region on the structure and mechanical properties of uranium. The initial material was uranium which had been cast, rolled in the ? region and quench-hardened from the region. Smallgrain recrystallized uranium has much higher strength than the initial coarse-grained uranium. Approximate recrystallization

G. Ya. Sergeev; V. V. Titova; L. I. Kolobneva

1961-01-01

309

THE RECOVERY OF URANIUM FROM GAS MIXTURE  

DOEpatents

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, S.H.

1964-03-17

310

METHOD OF APPLYING COPPER COATINGS TO URANIUM  

Microsoft Academic Search

A method is presented for protecting metallic uranium, which comprises ; anodic etching of the uranium in an aqueous phosphoric acid solution containing ; chloride ions, cleaning the etched uranium in aqueous nitric acid solution, ; promptly electro-plating the cleaned uranium in a copper electro-plating bath, ; and then electro-plating thereupon lead, tin, zinc, cadmium, chromium or nickel ; from

Gray

1959-01-01

311

PREPARATION OF URANIUM-ALUMINUM ALLOYS  

DOEpatents

A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

Moore, R.H.

1962-09-01

312

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

313

National Uranium Resource Evaluation: Durango Quadrangle, Colorado  

Microsoft Academic Search

The Durango Quadrangle (2), Colorado, was evaluated using National Uranium Resource Evaluation criteria to determine environments favorable for uranium deposits. General reconnaissance, geologic and radiometric investigations, was augmented by detailed surface examination and radiometric and geochemical studies in selected areas. Eight areas favorable for uranium deposits were delineated. Favorable geologic environments include roscoelite-type vanadium-uranium deposits in the Placerville and Barlow

N. J. Theis; M. E. Madson; G. C. Rosenlund; W. R. Reinhart; H. A. Gardner

1981-01-01

314

Conversion of uranium hexafluoride to oxides of uranium  

SciTech Connect

In a process for the conversion of uranium hexafluoride to a uranium oxide by injecting uranium hexafluoride and dry steam into a first region of a vessel so as to form a plume of particles of uranyl fluoride and reacting the uranyl fluoride in a second region of the vessel with a countercurrent flow of steam and/or hydrogen the operation of the process is such that a major proportion of the uranyl fluoride is caused to circulate within the first region so that the original uranyl fluoride particles are able to grow and agglomerate in a dendritic manner.

Butler, G.; Gillies, G.; Heal, T.; Littlechild, J.

1983-08-09

315

ELUTION OF URANIUM FROM RESIN  

DOEpatents

A method is described for eluting uranium from anion exchange resins so as to decrease vanadium and iron contamination and permit recycle of the major portion of the eluats after recovery of the uranium. Diminution of vanadium and iron contamination of the major portion of the uranium is accomplished by treating the anion exchange resin, which is saturated with uranium complex by adsorption from a sulfuric acid leach liquor from an ore bearing uranium, vanadium and iron, with one column volume of eluant prepared by passing chlorine into ammonium hydroxide until the chloride content is about 1 N and the pH is about 1. The resin is then eluted with 8 to 9 column volumes of 0.9 N ammonium chloride--0.1 N hydrochloric acid solution. The eluants are collected separately and treated with ammonia to precipitate ammonium diuranate which is filtered therefrom. The uranium salt from the first eluant is contaminated with the major portion of ths vanadium and iron and is reworked, while the uranium recovered from the second eluant is relatively free of the undesirable vanadium and irons. The filtrate from the first eluant portion is discarded. The filtrate from the second eluant portion may be recycled after adding hydrochloric acid to increase the chloride ion concentration and adjust the pH to about 1.

McLEan, D.C.

1959-03-10

316

f-f origin of the insulating state in uranium dioxide: X-ray absorption experiments and first-principles calculations  

NASA Astrophysics Data System (ADS)

We have performed x-ray absorption experiments on uranium dioxide (UO2) at the O 1s, U 4d, U 4f, and U 5d edges. After comprehensive energy calibrations for O 1s, U 4d, and U 4f spectra, we have used the U 4d and 4f spectra to sort the energetic positions of the 5f and the 6d states in the unoccupied band unambiguously. This demonstrates conclusively that UO2 is an f-f Mott-Hubbard insulator, where the electronic repulsion between f electrons is responsible for the insulating state. Calculations performed within the U-corrected generalized gradient approximation of the optical response of UO2 permit direct comparison with the absorption spectra and confirm the experimental results.

Yu, S.-W.; Tobin, J. G.; Crowhurst, J. C.; Sharma, S.; Dewhurst, J. K.; Olalde-Velasco, P.; Yang, W. L.; Siekhaus, W. J.

2011-04-01

317

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

318

URANIUM RECOVERY FROM NUCLEAR FUEL  

DOEpatents

A process of recovering uranium from a UF/sub 4/-NaFZrF/sub 4/ mixture by spraying the molten mixture at about 200 deg C in nitrogen of super- atmospheric pressure into droplets not larger than 100 microns, and contacting the molten droplets with fluorine at about 200 deg C for 0.01 to 10 seconds in a container the walls of which have a temperature below the melting point of the mixture is described. Uranium hexafluoride is formed and volatilized and the uranium-free salt is solidified. (AEC)

Vogel, R.C.; Rodger, W.A.

1962-04-24

319

Determination of uranium in zircon  

USGS Publications Warehouse

A routine fluorimetric procedure is described for the determination of trace amounts of uranium in zircon. It employs the direct extraction of uranyl nitrate with ethyl acetate using phosphate as a retainer for zirconium. Submicrogram amounts or uranium are separated in the presence of 100,000 times the amount of zirconium. The modified procedure has been worked out using synthetic mixtures of known composition and zircon. Results of analyses have an accuracy of 97-98% of the contained uranium and a standard deviation of less than 2.5%. ?? 1959.

Cuttitta, F.; Daniels, G. J.

1959-01-01

320

Measurement of uranium enrichment for gaseous uranium at low pressure  

NASA Astrophysics Data System (ADS)

X-ray fluorescence determines the amount of total uranium present in gaseous UF6 inside cascade header pipes of a uranium centrifuge enrichment facility. A highly collimated source, highly collimated detctor, and a very rigid, reproducible geometry are required. Two measurements of the 185.7 keV gamma ray from U-235 using two collimators determine the amount of U-235 present only in the gas phase. The ratio of the gas only U235 signal to the total uranium gas only signal is directly proportional to the enrichment of the process UF6 gas. This measurement technique is independent of the deposit that forms on a surface in contact with UF6. This measurement technique is independent of the pressure of the gaseous UF6. This technique has the required sensitivity to determine whether the process gas is of uranium enrichment less than or equal to 20% or 20%.

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

321

Technology for increasing the uranium-235 isotopic abundance in natural uranium feed on a productive scale  

SciTech Connect

First, the uses of enriched uranium are discussed, then the technologies for enriching uranium, how these technologies are developed and applied, and the current and future supplies of enriched uranium compared to forecasts of demand are explained. 29 figs.

Evans, E.C.

1985-04-19

322

Elements beyond uranium  

SciTech Connect

This book is the 12th volume in a series on transuranium elements. Varied techniques for production of these elements, the methods used in the identification, and the exquisitely refined microchemical techniques required to deal wth samples sometimes involving only a few atoms are described in detail. The chapter on synthesis of the new elements is liberally laced with reminiscences of the proud progenitors as well as the criteria for the discovery of a new chemical element. The authors lament that the superheavy elements (elements in the region of atomic number 114) still elude detection even though their creation should be possible, and some, at least, should survive long enough to be detected. One chapter in the book is devoted to practical applictions of uranium, and the transuranic elements.

Seaborg, G.T.; Loveland, W.D.

1990-01-01

323

The Core: Uranium Institute  

NSDL National Science Digital Library

The Uranium Institute (UI) is an international organization comprised of members who are involved in all "stages of the production of nuclear generated electricity" in the hopes of promoting the use of nuclear energy to supply energy demands, while minimizing environmental risks. The goals of the Institute are to monitor the outlook for the world's nuclear fuel markets, provide a forum between the nuclear fuel industry and the international organizations concerned with environmental issues as well as energy policy, and to make the public gain a general understanding of the nuclear fuel cycle. Sections are divided into three categories: Features, the UI, and the Industry. Although the site is somewhat news-oriented, it informs users about industries involved with nuclear-generated electricity and how they manage radioactive waste.

1999-01-01

324

Disposition of uranium-233  

SciTech Connect

The US is developing a strategy for the disposition of surplus weapons-usable uranium-233 ({sup 233}U). The strategy (1) identifies the requirements for the disposition of surplus {sup 233}U; (2) identifies potential disposition options, including key issues to be resolved with each option; and (3) defines a road map that identifies future key decisions and actions. The disposition of weapons-usable fissile materials is part of a US international arms-control program for reduction of the number of nuclear weapons and the quantities of nuclear-weapons-usable materials worldwide. The disposition options ultimately lead to waste forms requiring some type of geological disposal. Major options are described herein.

Tousley, D.R. [Dept. of Energy, Washington, DC (United States). Office of Fissile Materials Disposition; Forsberg, C.W.; Krichinsky, A.M. [Oak Ridge National Lab., TN (United States)

1997-10-16

325

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

326

Deep Drawing of Uranium Metal.  

National Technical Information Service (NTIS)

A procedure was developed to fabricate uranium forming blanks with high ''draw-ability'' so that cup shapes could be easily and uniformly deep drawn. The overall procedure involved a posttreatment to develop optimum mechanical and structural properties in...

R. J. Jackson M. R. Lundberg

1987-01-01

327

Yeelirrie Uranium Project - Western Australia.  

National Technical Information Service (NTIS)

The Yeelirrie uranium deposit is situated approximately 670 kilometers north-east of Perth, the capital of the State of Western Australia and approximately 500 kilometers north of the mining town of Kalgoorlie. The surrounding areas are somewhat desolate ...

R. J. Crawley

1982-01-01

328

Reactor for preparing uranium trioxide  

SciTech Connect

Nuclear fuels, such as uranium trioxide, are prepared by thermal decomposition of a nitrate in a fluidized bed reactor. The fluidized bed reactor for preparing uranium trioxide from uranyl nitrate by thermal decomposition has (a) a rectangularly shaped bed which satisfies the critical safety shape of /sup 235/U, (b) plural holes to supply an aqueous solution of uranyl nitrate into the reactor, (c) at least two reaction rooms divided by barriers, the bottoms of the barriers being capable of being lifted to control their distance from the floor and a mechanism by which uranium trioxide powder is taken out mainly by being overflowed from the top of the barriers through the reaction rooms, (d) heating means inside and outside of the fluidized-bed, and (e) a head structure which is upwardly V-shaped. Continuous operation can be attained with ease, and uranium trioxide can be made efficiently.

Ueda, K.

1983-08-16

329

Interview regarding Uzbekistan Uranium Reserves  

SciTech Connect

In his first extensive interview, Nicolay I. Kuchersky, President of Kyzylkumredmetzoloto and General Director of the Novoi Mining and Metallurgy Combine, discusses the business of mining uranium in Uzbekistan. This is a companion article following one that took an in-depth look at this newly independent country's activities in uranium mining. The president of the responsible organization discusses plans, wages, and interactions with the western world.

Kuchersky, N.

1993-05-01

330

Aging effects in uranium tritide  

Microsoft Academic Search

The aging behaviors of uranium tritide, such as the release of helium-3, changes of equilibrium desorption isotherms, and tritium heels, have been investigated. It is suggested that part of 3He from decay should be retained in the aged uranium tritide. The plateau of PCT curve is still wide and flat, and the change of the equilibrium plateau pressure is inconspicuous.

Rong Li; Ying Sun; Yongjun Wei; Wensheng Guo

2006-01-01

331

Systematic Analysis of Uranium Isotopes  

Microsoft Academic Search

We describe recent nuclear model calculations and evaluations of neutron reactions on the uranium isotopes 232-241U in the keV to 30-MeV energy range. This work makes use of extensive sets of measurements for fission, elastic, inelastic, (n,xn) and capture, as well as fission probability data. The 235U(n.f) standard cross section was revised, and the fission cross sections of the uranium

Phillip G. Young; Mark B. Chadwick; Robert E. Macfarlane; David G. Madland; Peter Moeller; William B. Wilson; Patrick Talou; Toshihiko Kawano

2005-01-01

332

Systematic Analysis of Uranium Isotopes  

Microsoft Academic Search

We describe recent nuclear model calculations and evaluations of neutron reactions on the uranium isotopes 232241U in the keV to 30-MeV energy range. This work makes use of extensive sets of measurements for fission, elastic, inelastic, (n,xn) and capture, as well as fission probability data. The 235U(n.f) standard cross section was revised, and the fission cross sections of the uranium

Phillip G. Young; Mark B. Chadwick; Robert E. MacFarlane; David G. Madland; William B. Wilson; Patrick Talou; Toshihiko Kawano

2005-01-01

333

LIQUID METAL COMPOSITIONS CONTAINING URANIUM  

DOEpatents

Liquid metal compositions containing a solid uranium compound dispersed therein is described. Uranium combines with tin to form the intermetallic compound USn/sub 3/. It has been found that this compound may be incorporated into a liquid bath containing bismuth and lead-bismuth components, if a relatively small percentage of tin is also included in the bath. The composition has a low thermal neutron cross section which makes it suitable for use in a liquid metal fueled nuclear reactor.

Teitel, R.J.

1959-04-21

334

HEAT TREATMENT OF ELECTROPLATED URANIUM  

DOEpatents

A method is described for improving electroplated coatings on uranium. Such coatings are often porous, and in an effort to remedy this, the coatings are heat treated by immersing the coated specimen ln a bath of fused salt or molten methl. Since the hase metal, uranium, is an active metal, such a procedure often results in reactions between the base metal and the heating medium. This difficulty can be overcome by using liquid organopolysiloxanes as the heating medium.

Hoglund, P.F.

1958-07-01

335

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

336

Reactor for preparing uranium trioxide  

Microsoft Academic Search

Nuclear fuels, such as uranium trioxide, are prepared by thermal decomposition of a nitrate in a fluidized bed reactor. The fluidized bed reactor for preparing uranium trioxide from uranyl nitrate by thermal decomposition has (a) a rectangularly shaped bed which satisfies the critical safety shape of ²³⁵U, (b) plural holes to supply an aqueous solution of uranyl nitrate into the

1983-01-01

337

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.

338

MELTING AND PURIFICATION OF URANIUM  

DOEpatents

A process is described for treating uranium ingots having inner metal portions and an outer oxide skin. The method consists in partially supporting such an ingot on the surface of a grid or pierced plate. A sufficient weight of uranium is provided so that when the mass becomes molten, the oxide skin bursts at the unsupported portions of its bottom surface, allowing molten urantum to flow through the burst skin and into a container provided below.

Spedding, F.H.; Gray, C.F.

1958-09-16

339

FLUORIMETRIC DETERMINATION OF URANIUM TRACES  

Microsoft Academic Search

For the quantitative determination of natural uranium a fluorimeter, ; which works according to the reflection principle, was built. With the use of a ; NaF--LiF mixture 5 x 10⁻⁹ g and with the carbonate mixture 10⁻⁹ g of ; uranium per melt test could be detected. The mean relative apparatus error was ; from 1.1 to 10% of the

1963-01-01

340

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

341

Mortality among uranium enrichment workers  

SciTech Connect

A retrospective cohort mortality study was conducted on workers at the Portsmouth Uranium Enrichment facility in Pike County, Ohio, in response to a request from the Oil, Chemical and Atomic Workers International Local 3-689 for information on long-term health effects. Primary hazards included inhalation exposure to uranyl fluoride containing uranium-235 and uranium-234, technetium-99 compounds, and hydrogen-fluoride. Uranium-238 presented a nephrotoxic hazard. Statistically significant mortality deficits based on U.S. death rates were found for all causes, accidents, violence, and diseases of nervous, circulatory, respiratory, and digestive systems. Standardized mortality rates were 85 and 54 for all malignant neoplasms and for other genitourinary diseases, respectively. Deaths from stomach cancer and lymphatic/hematopoietic cancers were insignificantly increased. A subcohort selected for greatest potential uranium exposure has reduced deaths from these malignancies. Insignificantly increased stomach cancer mortality was found after 15 years employment and after 15 years latency. Routine urinalysis data suggested low internal uranium exposures.

Brown, D.P.; Bloom, T.

1987-01-01

342

Beneficial Uses of Depleted Uranium  

SciTech Connect

Naturally occurring uranium contains 0.71 wt% {sup 235}U. In order for the uranium to be useful in most fission reactors, it must be enriched the concentration of the fissile isotope {sup 235}U must be increased. Depleted uranium (DU) is a co-product of the processing of natural uranium to produce enriched uranium, and DU has a {sup 235}U concentration of less than 0.71 wt%. In the United States, essentially all of the DU inventory is in the chemical form of uranium hexafluoride (UF{sub 6}) and is stored in large cylinders above ground. If this co-product material were to be declared surplus, converted to a stable oxide form, and disposed, the costs are estimated to be several billion dollars. Only small amounts of DU have at this time been beneficially reused. The U.S. Department of Energy (DOE) has begun the Beneficial Uses of DU Project to identify large-scale uses of DU and encourage its reuse for the primary purpose of potentially reducing the cost and expediting the disposition of the DU inventory. This paper discusses the inventory of DU and its rate of increase; DU disposition options; beneficial use options; a preliminary cost analysis; and major technical, institutional, and regulatory issues to be resolved.

Brown, C. [U.S. Department of Energy, Germantown, MD (United States); Croff, A.G.; Haire, M. J. [Oak Ridge National Lab., TN (United States)

1997-08-01

343

THE DETERMINATION OF NIOBIUM IN URANIUM NIOBIUM ALLOYS  

Microsoft Academic Search

The niobium-uranium alloy is dissolved in hydrofluoric nitric acids and ;\\u000a the fluoride removed by fuming sulfuric acid. The niobium is hydrolyzed in an ;\\u000a acid-sulfur dioxide medium and converted to niobic oxide by ignition at 900 deg ;\\u000a C. The method covers the determination of niobium in niobium-uranium alloys ;\\u000a having a niobium content of 8 to 12%. Metals

G. W. Goward; T. M. Reinhold; V. R. Wiederkehr

1958-01-01

344

Relationship between isotopic uranium activities and total uranium at various uranium enrichments  

Microsoft Academic Search

There is often a need to calculate isotopic uranium activities from total uranium mass or gamma spectrometry measurement data.\\u000a This calculation is based on a model of the relationship of the234U activity to that of235U since both are enriched together in the normal gaseous diffusion enrichment process. This paper presents equations for calculating\\u000a these activities that have been developed from

T. L. Rucker; C. M. Johnson

1998-01-01

345

Process for alloying uranium and niobium  

DOEpatents

Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uranium 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, C.E.; Northcutt, W.G.; Masters, D.R.; Chapman, L.R.

1990-12-31

346

SOLVENT EXTRACTION PROCESS FOR URANIUM RECOVERY  

DOEpatents

A process is described for extracting uranium from uranium ore, wherein the uranium is substantially free from molybdenum contamination. In a solvent extraction process for recovering uranium, uranium and molybdenum ions are extracted from the ore with ether under high acidity conditions. The ether phase is then stripped with water at a lower controiled acidity, resaturated with salting materials such as sodium nitrate, and reextracted with the separation of the molybdenum from the uranium without interference from other metals that have been previously extracted.

Clark, H.M.; Duffey, D.

1958-06-17

347

Depleted uranium dioxide melting in cold crucible melter and production of granules from the melt for use in casks for spent nuclear fuel and radioactive wastes  

SciTech Connect

This paper describes the results of a joint research program between the Russian Research Institute of Chemical Technology and Oak Ridge National Laboratory in the United States to develop new radiation shielding materials for use in the construction of casks for spent nuclear fuel (SNF) and radioactive wastes. Research and development is underway to develop SNF storage, transport, and disposal casks using shielding made with two new depleted uranium dioxide (DUO{sub 2}) materials: a DUO{sub 2}-steel cermet, and, DUCRETE with DUAGG (DUO{sub 2} aggregate). Melting the DUO{sub 2} and allowing it to freeze will produce a near 100% theoretical density product and assures that the product produces no volatile materials upon subsequent heating. Induction cold-crucible melters (ICCM) are being developed for this specific application. An ICCM is, potentially, a high throughput low-cost process. Schematics of a pilot facility were developed for the production of molten DUO{sub 2} from DU{sub 3}O{sub 8} to produce granules <1 mm in diameter in a continuous mode of operation. Thermodynamic analysis was conducted for uranium-oxygen system in the temperature range from 300 to 4000 K in various gas mediums. Temperature limits of stability for various uranium oxides were determined. Experiments on melting DUO{sub 2} were carried out in a high frequency ICCM in a cold crucible with a 120 mm in diameter. The microstructure of molten DUO{sub 2} was studied and lattice parameters were determined. It was experimentally proved, and validated by X-ray analysis, that an opportunity exists to produce molten DUO{sub 2} from mixed oxides (primarily DU{sub 3}O{sub 8}) by reduction melting in ICCM. This will allow using DU{sub 3}O{sub 8} directly to make DUO{sub 2}-a separate unit operation to produce UO{sub 2} feed material is not needed. Experiments were conducted concerning the addition of alloying components, gadolinium et al. oxides, into the DUO{sub 2} melt while in the crucible. These additives improve neutron and gamma radiation shielding and operation properties of the final solids. Cermet samples of 50 wt % DUO{sub 2} were produced. (authors)

Gotovchikov, V.T.; Seredenko, V.A.; Shatalov, V.V.; Mironov, B.S.; Kaplenkov, V.N.; Seredenko, A.V.; Saranchin, V.K.; Shulgin, A.S. [All-Russian Research Institute of Chemical Technology (ARRICT), Moscow (Russian Federation); Haire, M.J.; Forsberg, C.W. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

2007-07-01

348

The end of cheap uranium.  

PubMed

Historic data from many countries demonstrate that on average no more than 50-70% of the uranium in a deposit could be mined. An analysis of more recent data from Canada and Australia leads to a mining model with an average deposit extraction lifetime of 102 years. This simple model provides an accurate description of the extractable amount of uranium for the recent mining operations. Using this model for all larger existing and planned uranium mines up to 2030, a global uranium mining peak of at most 584 ktons around the year 2015 is obtained. Thereafter we predict that uranium mine production will decline to at most 545 ktons by 2025 and, with the decline steepening, to at most 415 ktons around 2030. This amount will not be sufficient to fuel the existing and planned nuclear power plants during the next 10-20 years. In fact, we find that it will be difficult to avoid supply shortages even under a slow 1%/year worldwide nuclear energy phase-out scenario up to 2025. We thus suggest that a worldwide nuclear energy phase-out is in order. If such a slow global phase-out is not voluntarily effected, the end of the present cheap uranium supply situation will be unavoidable. The result will be that some countries will simply be unable to afford sufficient uranium fuel at that point, which implies involuntary and perhaps chaotic nuclear phase-outs in those countries involving brownouts, blackouts, and worse. PMID:23683936

Dittmar, Michael

2013-05-16

349

Atomistic properties of ? uranium  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

350

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

351

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

352

Microbial Accumulation of Uranium, Radium, and Cesium.  

National Technical Information Service (NTIS)

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 (hour...

G. W. Strandberg S. E. Shumate J. R. Parrott S. E. North

1981-01-01

353

POTENTIAL TOXICITY OF URANIUM IN WATER  

EPA Science Inventory

The nephrotoxic responses of mammalian species, including humans, to injected, inhaled, ingested, and topically applied uranium compounds have been thoroughly investigated. Because there appears to be on unequivocal reports of uranium-induced radiation effects in humans, it is ne...

354

New reagent for uranium - plutonium partitioning.  

National Technical Information Service (NTIS)

We have investigated the feasibility of achieving uranium-plutonium partition of the Purex Process by using a new reagent: Uranous nitrate - hydroxylamine nitrate. Laboratory test tube studies and uranium-plutonium partitioning runs have shown that pluton...

M. Germain B. Gillet J. Y. Pasquiou

1990-01-01

355

Liquid Uranium Reaction with Coated Graphite Crucibles.  

National Technical Information Service (NTIS)

Carbon contamination in uranium from yttria-coated graphite crucibles containing uncoated defects has been measured at typical foundry melting conditions as a function of defect area. The reaction of liquid uranium with graphite at crucible coating defect...

R. H. Reiner

1987-01-01

356

Alternatives for Disposal of Depleted Uranium Waste.  

National Technical Information Service (NTIS)

Large quantities of depleted uranium wastes are generated at Eglin AFB each year due to testing of armor penetrating munitions. The majority of this waste consists of sand contaminated with small amounts of depleted uranium. In the study various alternati...

C. W. Mallory J. G. Funk W. S. Sanner

1985-01-01

357

National Uranium Resource Evaluation: Pratt Quadrangle, Kansas.  

National Technical Information Service (NTIS)

Surface reconnaissance and detailed subsurface studies were done within the Pratt Quadrangle, Kansas, to evaluate uranium favorability using National Uranium Resource Evaluation criteria. These studies were designed in part to follow up previous airborne ...

C. L. Fair D. E. Smit

1982-01-01

358

National Uranium Resource Evaluation: Casper Quadrangle, Wyoming.  

National Technical Information Service (NTIS)

The Casper Quadrangle, Wyoming, was evaluated for areas favorable for the occurrence of uranium deposits. Examination of surface exposures of known uranium occurrences, reconnaissance geochemical sampling, and ground radiometric surveys were conducted. An...

E. J. Milton J. R. Griffin

1982-01-01

359

Impacts of Canada's Uranium Mining Industry.  

National Technical Information Service (NTIS)

This study examines economic and environmental impacts of uranium mining in Canada and compares these impacts with those of other extractive and energy industries. The uranium industry generates taxes and royalties, income, employment, foreign exchange ea...

G. J. Holman

1982-01-01

360

Statistical Data of the Uranium Industry.  

National Technical Information Service (NTIS)

Statistical data are given on the following: ore and concentrate purchases; uranium resources--ore reserves, ore production, and potential resources; distribution of $8, $10, and $15 reserves; drilling statistics; uranium exploration expenditures; land ho...

1975-01-01

361

Granulation of Uranium Trioxide and Ammonium Diuranate.  

National Technical Information Service (NTIS)

The possibilities of the granulation in small laboratory scale of the uranium trioxide and ammonium diuranate were examined. For the uranium trioxide it was stated, that the most advantageous results were obtained by means of the granulation with rotary p...

R. Wlodarski Z. Nowakowska

1975-01-01

362

National Uranium Resource Evaluation: Durango Quadrangle, Colorado.  

National Technical Information Service (NTIS)

The Durango Quadrangle (2 exp 0 ), Colorado, was evaluated using National Uranium Resource Evaluation criteria to determine environments favorable for uranium deposits. General reconnaissance, geologic and radiometric investigations, was augmented by deta...

N. J. Theis M. E. Madson G. C. Rosenlund W. R. Reinhart H. A. Gardner

1981-01-01

363

Reducing emissions from uranium dissolving  

SciTech Connect

This study was designed to assess the feasibility of decreasing NO[sub x] emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO[sub x] fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO[sub x] emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO[sub 2] which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

1992-10-01

364

Reducing emissions from uranium dissolving  

SciTech Connect

This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2} which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

1992-10-01

365

RECOVERY OF URANIUM VALUES FROM URANIUM BEARING RAW MATERIALS  

DOEpatents

Uranium leaching from ground uranium-bearing raw materials using MnO/sub 2/ in H/sub 2/SO/sub 4/ is described. The MnO/sub 2/ oxidizes U to the leachable hexavalent state. The MnO/sub 2/ does not replace Fe normally added, because the Fe complexes P and catalyzes the MnO/sub 2/ reaction. Three examples of continuous processes are given, but batch operation is also possible. The use of MnO/sub 2/ makes possible recovery of very low U values. (T.R.H.)

Michal, E.J.; Porter, R.R.

1959-06-16

366

URANIUM BISMUTHIDE DISPERSION IN MOLTEN METAL  

DOEpatents

The formation of intermetallic bismuth compounds of thorium or uranium dispersed in a liquid media containing bismuth and lead is described. A bismuthide of uranium dispersed in a liquid metal medium is formed by dissolving uranium in composition of lead and bismuth containing less than 80% lead and lowering the temperature of the composition to a temperature below the point at which the solubility of uranium is exceeded and above the melting point of the composition.

Teitel, R.J.

1959-10-27

367

Phosphate Bariers 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 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.

Peter C. Burns

2007-01-26

368

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

369

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, P.S.; Sheinberg, H.; Hogan, B.M.; Lewis, H.D.; Dickinson, J.M.

1989-03-28

370

Liquid uranium reaction with coated graphite crucibles  

Microsoft Academic Search

Carbon contamination in uranium from yttria-coated graphite crucibles containing uncoated defects has been measured at typical foundry melting conditions as a function of defect area. The reaction of liquid uranium with graphite at crucible coating defects is proportional to the defect surface area and is approx.270 times greater than the reaction at a coated region of equivalent area. Uranium carbon

1987-01-01

371

National uranium resource evaluation, Havre Quadrangle, Montana  

Microsoft Academic Search

The Havre, Montana, 1° x 2° Quadrangle was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for uranium deposits, using criteria established for the National Uranium Resource Evaluation program. The methods of surface investigationn included evaluation of aerial radiometric and hydrogeochemical and stream-sediment reconnaissance data, verification of reported uranium occurrences, and general field geology

Gebhardt

1982-01-01

372

Medical effects of internal contamination with uranium.  

PubMed

The purpose of this work is to present an outline of the metabolic pathways of uranium isotopes and compounds, medical consequences of uranium poisoning, and an evaluation of the therapeutic alternatives in uranium internal contamination. The chemical toxicity of uranium has been recognized for more than two centuries. Animal experiments and human studies are conclusive about metabolic adverse affects and nephro- toxicity of uranium compounds. Radiation toxicity of uranium isotopes has been recognized since the beginning of the nuclear era, with well documented evidence of reproductive and developmental toxicity, as well as mutagenic and carcinogenic consequences of uranium internal contamination. Natural uranium (238U), an alpha emitter with a half-life of 4.5x10(9) years, is one of the primordial substances of the universe. It is found in the earth's crust, combined with 235U and 234U, alpha, beta, and gamma emitters with respective half-lives of 7.1x10(8) and 2.5x10(5) years. A special emphasis of this paper concerns depleted uranium. The legacy of radioactive waste, environmental and health hazards in the nuclear industry, and, more recently, the military use of depleted uranium in the tactical battlefield necessitates further insight into the toxicology of depleted uranium. The present controversy over the radiological and chemical toxicity of depleted uranium used in the Gulf War warrants further experimental and clinical investigations of its effects on the biosphere and human organisms. PMID:9933897

Durakovi?, A

1999-03-01

373

Method for Preparation of Uranium Hydride.  

National Technical Information Service (NTIS)

A method for preparation of uranium hydride starting from hydrogen and uranium is described. In the temperature range of 250 deg up to 350 deg C, and pressures above 10 torr, hydrogen reacts smoothly with uranium turnings forming a fine black or dark gray...

M. S. Gorski M. Goncalves A. Mirage W. Lima

1985-01-01

374

ENRICHED-URANIUM HYDRIDE CRITICAL ASSEMBLIES  

Microsoft Academic Search

Assemblies considered consist of approximate spheres of enriched-uranium ; hydride composition (approximating UH) in 8-in. thick normal uranium and ; nickel reflectors and in a uranium reflector with nickel liner. Data are of the ; following types- (1) critical sizes, (2) values of Rossi alpha in the ; neighborhood of delayed critical, (3) activation rates of various internal ; neutron

G. A. Linenberger; J. D. Orndoff; H. C. Paxton

1960-01-01

375

Thorium and uranium contents of some sandstones  

Microsoft Academic Search

Average values have been obtained by gamma-ray spectrometry for the thorium and uranium contents of some orthoquartzites and graywackes. The Atoka and Jackfork quartz sandstones of western Arkansas average approximately 4 ppm thorium and 1 ppm uranium. The Umpqua and Tyee graywackes of western Oregon average approximately 7 ppm thorium and 2 ppm uranium. Weighted average concentrations for all sandstones

John J. W. Rogers; Keith A. Richardson

1964-01-01

376

Recovery of uranium by immobilized microorganisms  

Microsoft Academic Search

Some attempts were made to recover uranium from sea and fresh water using immobilized Streptomyces viridochromogenes and Chlorella regularis cells. The cells immobilized in polyacrylamide gel have the most favorable features for uranium recovery; high adsorption ability, good mechanical properties, and applicability in a column system. The adsorption of uranium by the immobilized cells is not affected by the pH

Akira Nakajima; Takao Horikoshi; Takashi Sakaguchi

1982-01-01

377

Accumulation of Uranium by Immobilized Persimmon Tannin  

Microsoft Academic Search

We have discovered that the extracted juice of unripe astringent persimmon fruit, designated as kakishibu or shibuol, has an extremely high affinity for uranium. To develop efficient adsorbents for uranium, we tried to immobilize kakishibu (persimmon tannin) with various aldehydes and mineral acids. Persimmon tannin immobilized with glutaraldehyde can accumulate 1.71 g (14 mEq U) of uranium per gram of

Takashi Sakaguchi; Akira Nakajima

1994-01-01

378

Iron EDTA chelate catalyzed oxidation of uranium  

SciTech Connect

Uranium ore deposits which contain uranium in the relatively insoluble tetravalent state are readily selectively leached in situ to recover relatively pure uranium compounds, by: (A) passing through the ore deposit a relatively dilute aqueous leach solution of ammonium bicarbonate, ferric ammonium ethylenediaminetetraacetic acid (EDTA), and a source of oxygen, the leach solution converting the tetravalent uranium to hexavalent uranium which readily dissolves in the leach solution; (B) withdrawing the reacted leach solution enriched in dissolved uranium from the ore deposit; and (C) stripping the uranium from the withdrawn leach solution. The stripping of the uranium from the leach solution is preferably accomplished by countercurrent flow of the enriched leach solution to a column of base anion exchange material which preferentially extracts the uranium. Base anion exchange material loaded with uranium is separated from the leach solution and is treated with an aqueous alkaline eluant to extract the uranium and to regenerate the base anion exchange material. The stripped leach solution is adjusted by adding ammonium bicarbonate, peroxide, and ferric ammonium edta, and its ph corrected if necessary, and the leach solution is recycled through the ore deposit. The uranium bearing eluant is then acidified and treated with ammonia to precipitate relatively pure ammonium diuranate (Adu).

Jackovitz, J.F.; Panson, A.J.; Pantier, E.A.

1981-01-06

379

IMPREGNATION OF POROUS GRAPHITE WITH URANIUM  

Microsoft Academic Search

A method for impregnating porous graphite with UO using uranyl ; nitrate hexahydrate is described. The theoretical amount of possible ; impregmation based on graphite of 25% porosity and apparent density 1.67 using ; uranyl nitrate hexahydrate, uranium carbide, and uranium metal is tabulated. The ; analytical method employed for the determination of uranium in graphite is ; outlined. (L.T.W.)

Sanz

1947-01-01

380

Health effects of uranium: new research findings.  

PubMed

Recent plans for a nuclear renaissance in both established and emerging economies have prompted increased interest in uranium mining. With the potential for more uranium mining worldwide and a growth in the literature on the toxicology and epidemiology of uranium and uranium mining, we found it timely to review the current state of knowledge. Here, we present a review of the health effects of uranium mining, with an emphasis on newer findings (2005-2011). Uranium mining can contaminate air, water, and soil. The chemical toxicity of the metal constitutes the primary environmental health hazard, with the radioactivity of uranium a secondary concern. The update of the toxicologic evidence on uranium adds to the established findings regarding nephrotoxicity, genotoxicity, and developmental defects. Additional novel toxicologic findings, including some at the molecular level, are now emerging that raise the biological plausibility of adverse effects on the brain, on reproduction, including estrogenic effects, on gene expression, and on uranium metabolism. Historically, most epidemiology on uranium mining has focused on mine workers and radon exposure. Although that situation is still overwhelmingly true, a smaller emerging literature has begun to form around environmental exposure in residential areas near uranium mining and processing facilities. We present and critique such studies. Clearly, more epidemiologic research is needed to contribute to causal inference. As much damage is irreversible, and possibly cumulative, present efforts must be vigorous to limit environmental uranium contamination and exposure. PMID:22435323

Brugge, Doug; Buchner, Virginia

2011-01-01

381

THORIUM, URANIUM AND POTASSIUM IN SOME SANDSTONES  

Microsoft Academic Search

Thorinm, uranium, and potassium concentrations have been determined in ; nineteen sands and sandstones by gamma -ray spectrometry, fluorometric uranium ; analysis, and alpha counting. The samples were selected so that both common ; and extreme thorium and uranium ratios would be represented. The average and ; nearly uniform values found in orthoquartzitic, clay-free sands were potassium ; (as metal)

E. G. Murray; J. A. S. Adams

1958-01-01

382

Thorium, uranium and potassium in some sandstones  

Microsoft Academic Search

Thorium, uranium, and potassium concentrations have been determined in nineteen sands and sandstones by -ray spectrometry, fluorometric uranium analysis, and -counting. The samples were selected so that both common and extreme thorium and uranium ratios would be represented. The average and nearly uniform values found in orthoquartzitic, clay-free sands were potassium (as metal) 0.64 0.04 per cent ; thorium

Elaine G. Murray; John A. S. Adams

1958-01-01

383

CATALYZED OXIDATION OF URANIUM IN CARBONATE SOLUTIONS  

DOEpatents

A process is given wherein carbonate solutions are employed to leach uranium from ores and the like containing lower valent uranium species by utilizing catalytic amounts of copper in the presence of ammonia therein and simultaneously supplying an oxidizing agent thereto. The catalysis accelerates rate of dissolution and increases recovery of uranium from the ore. (AEC)

Clifford, W.E.

1962-05-29

384

The three primary uranium producers  

SciTech Connect

The world`s largest producers of uranium concentrates are Cameco, Cogema, and RTZ Corp. In 1989, these three producers will have a total net production interest of 37.7 million pounds U{sub 3}O{sub 8} and will participate in the production of 64.4 million pounds U{sub 3}O{sub 8}, or 65 percent of world production. By 1995, they are expected to participate in 68 percent of world production capability. While Cameco has found its success in a small corner of Saskatchewan, Cogema and RTZ have wide-ranging interests in a variety of political and economic settings. Cameco and Cogema provide downstream nuclear fuel services in addition to uranium concentrates. All three companies have a long history which traces the development of the uranium industry from infancy to maturity, and which puts them in the forefront of activity well into the next century.

NONE

1989-03-01

385

Recovery of uranium and lanthanides  

SciTech Connect

The authors discuss how solutions containing Ca(H{sub 2}PO{sub 4}){sub 2}-Ca(NO{sub 3}){sub 2-H}{sub 2}O and Ca(H{sub 2}PO{sub 4}){sub 2}-CaCI-H{sub 2}O obtained by leaching phosphate rock in situ or in dumps can be treated for uranium and lanthanides recovery prior to P{sub 2}O{sub 5}recovery as follows: In a nitrate system, uranium is first extracted by a mixture of bis(2-ethylehexl)phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in hexane followed by the extraction of the lanthanides with TBP. In a chloride system, uranium is first extracted by the same mixture, D2EHPA + TBP, followed by the extraction of lanthanides with D2EHPA in toluene.

Awadalla, F.T.; Habashi, F. (Laval Univ., Dept. of Mining and Metallurgy, Quebec City (CA))

1989-07-01

386

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

387

Potential exposures from uranium enrichment  

SciTech Connect

Public radiation doses resulting from gaseous diffusion enrichment facility effluents can be assessed by considering the potential environmental exposure pathways. These exposure pathways result from releases to both air and water, and rely on model evaluations to predict environmental transport. For most airborne releases, inhalation is the primary exposure pathway. Secondary pathways, including external exposure during plume passage, ingestion of uranium deposited on or contained in vegetation, and external exposure to uranium deposited on land surfaces also contribute. For liquid effluents, the primary exposure pathway is ingestion of drinking water, with secondary contributions to dose from ingestion of aquatic biota and ingestion of irrigated vegetation. This paper reviews the important considerations for conducting collective dose assessments for gaseous diffusion enrichment facility operations, including a discussion of the dosimetric considerations for uranium and a summary of estimated collective doses resulting from gaseous diffusion enrichment in the United States. 11 refs., 2 figs., 4 tabs.

Kennedy, W.E. Jr.

1987-09-01

388

Determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions by potentiometric titration  

SciTech Connect

A simple, fast method for the determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions has been adapted from the Davies-Gray volumetric method to meet the needs of Y-12. One-gram duplicate aliquots of uranium metal or uranium oxide are dissolved in 1:1 HNO/sub 3/ and concentrated H/sub 2/SO/sub 4/ to sulfur trioxide fumes, and then diluted to 100-mL volume. Duplicate aliquots are then weighed for analysis. For uranyl nitrate samples, duplicate aliquots containing between 50 and 150 mg of U are weighed and analyzed directly. The weighed aliquot is transferred to a Berzelius beaker; 1.5 M sulfamic acid is added, followed in order by concentrated phosphoric acid, 1 M ferrous sulfate, and (after a 30-second interval) the oxidizing reagent. After a timed 3-minute waiting period, 100 mL of the 0.1% vanadyl sulfate-sulfuric acid mixture is added. The sample is then titrated past its endpoint with standard potassium dichromate, and the endpoint is determined by second derivative techniques on a mV/weight basis.

Tucker, H.L.; McElhaney, R.J.

1983-01-01

389

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

390

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

391

Reaction of uranium oxides with chlorine and carbon or carbon monoxide to prepare uranium chlorides  

SciTech Connect

The preferred preparation concept of uranium metal for feed to an AVLIS uranium enrichment process requires preparation of uranium tetrachloride (UCI{sub 4}) by reacting uranium oxides (UO{sub 2}/UO{sub 3}) and chlorine (Cl{sub 2}) in a molten chloride salt medium. UO{sub 2} is a very stable metal oxide; thus, the chemical conversion requires both a chlorinating agent and a reducing agent that gives an oxide product which is much more stable than the corresponding chloride. Experimental studies in a quartz reactor of 4-cm ID have demonstrated the practically of some chemical flow sheets. Experimentation has illustrated a sequence of results concerning the chemical flow sheets. Tests with a graphite block at 850{degrees}C demonstrated rapid reactions of Cl{sub 2} and evolution of carbon dioxide (CO{sub 2}) as a product. Use of carbon monoxide (CO) as the reducing agent also gave rapid reactions of Cl{sub 2} and formation of CO{sub 2} at lower temperatures, but the reduction reactions were slower than the chlorinations. Carbon powder in the molten salt melt gave higher rates of reduction and better steady state utilization of Cl{sub 2}. Addition of UO{sub 2} feed while chlorination was in progress greatly improved the operation by avoiding the plugging effects from high UO{sub 2} concentrations and the poor Cl{sub 2} utilizations from low UO{sub 2} concentrations. An UO{sub 3} feed gave undesirable effects while a feed of UO{sub 2}-C spheres was excellent. The UO{sub 2}-C spheres also gave good rates of reaction as a fixed bed without any molten chloride salt. Results with a larger reactor and a bottom condenser for volatilized uranium show collection of condensed uranium chlorides as a loose powder and chlorine utilizations of 95--98% at high feed rates. 14 refs., 7 figs., 14 tabs.

Haas, P.A.; Lee, D.D.; Mailen, J.C.

1991-11-01

392

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

393

Distribution of uranium in rats implanted with depleted uranium pellets  

Microsoft Academic Search

During the Persian Gulf War, soldiers were injured with de- pleted uranium (DU) fragments. To assess the potential health risks associated with chronic exposure to DU, Sprague Dawley rats were surgically implanted with DU pellets at 3 dose levels (low, medium and high). Biologically inert tantalum (Ta) pellets were used as controls. At 1 day and 6, 12, and 18

T. C. Pellmar; A. F. Fuciarelli; J. W. Ejnik; J. Hogan; S. Strocko; C. Emond; H. M. Mottaz; M. R. Landauer

1999-01-01

394

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

2013-03-30

395

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

396

Photoluminescence and vibrational spectroscopic studies on weathered uranium oxides  

NASA Astrophysics Data System (ADS)

Spectroscopic studies were performed both on uranium oxides as baseline and on uranium oxides artificially weathered under known laboratory conditions in air, varying humidity, carbon dioxide concentration, temperature and exposure to UV light. Spectroscopic techniques included photoluminescence and diffuse reflectance FTIR. Photoluminescence measurements were made using a Spex Fluorolog-3TM spectrofluorometer with phosphorimeter. FTIR measurements were made using a Bomem MB157 FTIR spectrophotometer with DTGS detector and approximately 450 cm-1 cut-off and a Graseby SelectorTM diffuse reflectance accessory with special cells and diamond dust as diluent and internal standard. Weathered-related reactions involving the uranium oxides that have been studied include oxidation and the formation of hydroxides and carbonates. Data are discussed with respect to both the reactions of the uranium oxides in the study and in context of reaction chemistry and mechanisms that have been previously documented. The results will be discussed in the context of environmental monitoring.

Eastwood, Delyle; Martin, Jeffrey B.; Burggraf, Larry W.; Rand, Dennis S.; Zickafoose, Matthew S.; Perry, Dale L.

1999-02-01

397

Removal of uranium from aqueous HF solutions  

SciTech Connect

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 separating the solution from the settled particulates. The CaF2 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, H.; Seltzer, S.F.

1980-11-18

398

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); Seltzer, Steven F. (Paducah, KY)

1980-01-01

399

Method for producing uranium atomic beam source  

DOEpatents

A method for producing a beam of neutral uranium atoms is obtained by vaporizing uranium from a compound UM.sub.x heated to produce U vapor from an M boat or from some other suitable refractory container such as a tungsten boat, where M is a metal whose vapor pressure is negligible compared to that of uranium at the vaporization temperature. The compound, for example, may be the uranium-rhenium compound, URe.sub.2. An evaporation rate in excess of about 10 times that of conventional uranium beam sources is produced.

Krikorian, Oscar H. (Danville, CA)

1976-06-15

400

Isotopic ratio method for determining uranium contamination  

SciTech Connect

The presence of high concentrations of uranium in the subsurface can be attributed either to contamination from uranium processing activities or to naturally occurring uranium. A mathematical method has been employed to evaluate the isotope ratios from subsurface soils at the Rocky Flats Nuclear Weapons Plant (RFP) and demonstrates conclusively that the soil contains uranium from a natural source and has not been contaminated with enriched uranium resulting from RFP releases. This paper describes the method used in this determination which has widespread application in site characterizations and can be adapted to other radioisotopes used in manufacturing industries. The determination of radioisotope source can lead to a reduction of the remediation effort.

Miles, R.E.; Sieben, A.K.

1994-02-03

401

Oxidation states of uranium in depleted uranium particles from Kuwait.  

PubMed

The oxidation states of uranium in depleted uranium (DU) particles were determined by synchrotron radiation based mu-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 mu-XANES, DU particles ranging from submicrons to several hundred micrometers were observed. The median particle size depended on sources and sampling sites; small-sized particles (median 13 microm) were identified in swipes taken from the inside of DU penetrators holes in tanks and in sandy soil collected below DU penetrators, while larger particles (median 44 microm) were associated with fire in a DU ammunition storage facility. Furthermore, the (236)U/(235)U ratios obtained from accelerator mass spectrometry demonstrated that uranium in the DU particles originated from reprocessed fuel (about 10(-2) in DU from the ammunition facility, about 10(-3) for DU in swipes). Compared to well-defined standards, all investigated DU particles were oxidized. Uranium particles collected from swipes were characterized as UO(2), U(3)O(8) or a mixture of these oxidized forms, similar to that observed in DU affected areas in Kosovo. Uranium particles formed during fire in the DU ammunition facility were, however, present as oxidation state +5 and +6, with XANES spectra similar to solid uranyl standards. Environmental or health impact assessments for areas affected by DU munitions should therefore take into account the presence of respiratory UO(2), U(3)O(8) and even UO(3) particles, their corresponding weathering rates and the subsequent mobilisation of U from oxidized DU particles. PMID:15511555

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

2005-01-01

402

Domestic utility attitudes toward foreign uranium supply  

SciTech Connect

The current embargo on the enrichment of foreign-origin uranium for use in domestic utilization facilities is scheduled to be removed in 1984. The pending removal of this embargo, complicated by a depressed worldwide market for uranium, has prompted consideration of a new or extended embargo within the US Government. As part of its on-going data collection activities, Nuclear Resources International (NRI) has surveyed 50 domestic utility/utility holding companies (representing 60 lead operator-utilities) on their foreign uranium purchase strategies and intentions. The most recent survey was conducted in early May 1981. A number of qualitative observations were made during the course of the survey. The major observations are: domestic utility views toward foreign uranium purchase are dynamic; all but three utilities had some considered foreign purchase strategy; some utilities have problems with buying foreign uranium from particular countries; an inducement is often required by some utilities to buy foreign uranium; opinions varied among utilities concerning the viability of the domestic uranium industry; and many utilities could have foreign uranium fed through their domestic uranium contracts (indirect purchases). The above observations are expanded in the final section of the report. However, it should be noted that two of the observations are particularly important and should be seriously considered in formulation of foreign uranium import restrictions. These important observations are the dynamic nature of the subject matter and the potentially large and imbalanced effect the indirect purchases could have on utility foreign uranium procurement.

Not Available

1981-06-01

403

Determination of Uranium by Fluorometry.  

National Technical Information Service (NTIS)

The purpose of this work is to investigate the analytical parameters for the fluorometric determination of uranium applied in the analysis of geological materials. A mixture of 9 parts sodium fluoride, 45.5 parts sodium carbonate and 45.5 parts potassium ...

V. Leenanupan N. Ratanalert

1984-01-01

404

Recovery of uranium from solutions  

Microsoft Academic Search

A process is described of separating uranium from a dilute waste solution derived from the ammonium diuranate process of converting UF to UO and containing U(VI), fluoride ion, and ammonium ion, which comprises adding sodium hydrosulfite to the solution and recovering a precipitate containing fluorine, sodium, ammonium, and U(IV).

R. A. Hermens; J. B. Kendall; J. A. Partridge

1987-01-01

405

Why is Brazil enriching uranium?  

Microsoft Academic Search

In Brazil construction began in 1971 on Angra 1, a 626MW Westinghouse pressurized water reactor (PWR). It was completed in 1984. Later, Angra 2 (a Kraftwerk Union PWR) achieved commercial operation in 2000. Brazil is considering the construction of seven nuclear power plants over the next 15 years. In preparation for this nuclear industry expansion, Brazil is building a uranium

Belkis Cabrera-Palmer; Geoffrey Rothwell

2008-01-01

406

Thermodynamic Data for Uranium Fluorides.  

National Technical Information Service (NTIS)

Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF sub 4 and UF sub 6 , including UF sub 4 (solid and gas), U sub 4 F sub 17 (solid), U sub 2 F sub 9 (solid), UF sub 5 (solid and gas), U sub 2 F sub 10 (gas), and UF su...

J. M. Leitnaker

1983-01-01

407

Economics of Australian Uranium Mining.  

National Technical Information Service (NTIS)

This paper argues that the uranium industry in Australia is inefficient in economic terms. The author also states that it is inefficient in that various social resources are tied up in producing a material which has an intrinsically negative value, in bei...

P. McMahon

1983-01-01

408

Discordant Uranium-Lead Ages  

Microsoft Academic Search

The solution to the equation for the diffusion of lead and uranium from a sphere, including the effect of a pulse of metamorphism, is applied to the problem of discordant U-Pb ages. It is found that a pulse of metamorphism can greatly disturb the straight-line pattern found by Tilton, and the implications of this with regard to the thermal history

G. W. WETHERILL

1963-01-01

409

GRAIN REFINEMENT OF URANIUM BILLETS  

DOEpatents

A method of refining the grain structure of massive uranium billets without resort to forging is described. The method consists in the steps of beta- quenching the billets, annealing the quenched billets in the upper alpha temperature range, and extrusion upset of the billets to an extent sufficient to increase the cross sectional area by at least 5 per cent. (AEC)

Lewis, L.

1964-02-25

410

METHOD OF PURIFYING URANIUM METAL  

DOEpatents

The removal of lmpurities from uranlum metal can be done by a process conslstlng of contacting the metal with liquid mercury at 300 icient laborato C, separating the impunitycontalnlng slag formed, cooling the slag-free liquld substantlally below the point at which uranlum mercurlde sollds form, removlng the mercury from the solids, and recovering metallic uranium by heating the solids.

Blanco, R.E.; Morrison, B.H.

1958-12-23

411

Uranium enrichment and public policy  

Microsoft Academic Search

Alternative policies to the present government monopoly of the uranium enrichment process are discussed in this monograph. Alternative policies analyzed are continued government monopoly and operation by the Department of Energy, establishment of a government corporation, and complete relinquishing of government control with the private sector taking the risks of constructing additional capacity. The material is divided into 6 chapters.

1978-01-01

412

Mortality among Uranium Enrichment Workers.  

National Technical Information Service (NTIS)

A retrospective cohort mortality study was conducted on workers at the Portsmouth Uranium Enrichment facility (SIC-1094) in Pike County, Ohio, in response to a request from the Oil, Chemical and Atomic Workers International Local 3-689 for information on ...

D. P. Brown T. Bloom

1987-01-01

413

The Measurement of Uranium Enrichment  

Microsoft Academic Search

Uranium and plutonium samples are present in the nuclear fuel cycle in a wide variety of isotopic compositions; so the isotopic composition of a sample is often the object of measurement (see Chapter 8). In this chapter, we consider a special case of isotopic analysis: the determination, by radiation measurement, of the fractional abundance of a specific isotope of an

Hastings A Smith

414

Uranium enrichment: technology, economics, capacity  

Microsoft Academic Search

Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being

W. R. Jr. Voigt; P. R. Vanstrum; D. E. Saire; D. K. Gestson; S. E. Peske

1982-01-01

415

Ventilation requirements for uranium mines  

Microsoft Academic Search

The planning and operation of ventilation network systems for uranium mines require special considerations since ventilation is the primary technique of controlling ambient concentrations of radon progeny. The major environmental challenge facing the ventilation engineer is the requirement to dilute radon progeny to below the Working Level Month per year of worker exposure required by law. The application of large

C. Gherghel; E. De Souza

416

RADIATION HAZARDS IN URANIUM MINES  

Microsoft Academic Search

There is no conclusive evidence that lung cancer among uranium miners is ; wholly due to radioactivity, although most investigators believe that radon and ; its daughters are the causative agents. Health hazards involved are essentially ; inhalation hazards-- the exposure to external radiation being not very ; significant. Except in abnormal cases of radon contamination, which are ; infrequent,

Kamath

1958-01-01

417

Australia prepares for uranium mining  

Microsoft Academic Search

Six bills represent the Australian Government's legislative program for setting environmental policies that will permit uranium mining. The bills provide for coordinated research and monitoring activities, leasing of park lands and aboriginal land claims, application of nuclear safeguards, protective measures for health and safety, and enforcement of environmental requirements. Australia's goal is an orderly and responsible development of its sizeable

1978-01-01

418

Environmental Planning in Uranium Milling.  

National Technical Information Service (NTIS)

Effluents from uranium milling in the Achala region in the province of Cordoba are studied. Liquids from lixiviation-recovery and from precipitation-washing of yellow-cake were analyzed. Separation of both liquids before treatment and disposal is recommen...

L. F. Bertello

1987-01-01

419

Uranium uptake by hydroponically cultivated crop plants.  

PubMed

Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC(50) value about 0.1mM. Cucumis sativa represented the most resistant plant to uranium (EC(50)=0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1mM or 0.5mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. PMID:21486682

Soudek, Petr; Petrov, Srka; Beneov, Dagmar; Dvo?kov, Marcela; Van?k, Tom

2011-04-12

420

Recovery of uranium by a reverse osmosis process  

SciTech Connect

A method for concentrating and recovering uranium material from an aqueous solution, comprises passing a feed solution containing uranium through at least one reverse osmosis membrane system to concentrate the uranium, and then flushing the concentrated uranium solution with water in a reverse osmosis membrane system to further concentrate the uranium.

Cleary, J.G.; Stana, R.R.

1980-06-03

421

Chemical separation method for uranium isotopes  

SciTech Connect

This patent describes a process for isotopic enrichment of uranium. The steps of this process are: (A) preparing a solution of a uranium compound and solvent characterized in that the uranium compound involves a mixture of uranium isotopes. The isotopic mixture is to be enriched and the uranium compound is further characterized in that it possesses at least one excited state in solution. The respective isotopes in the excited state preferentially react at different rates by virtue of dissimilar nuclear magnetic moment contributions to the chemical kinetics of the excited state reactions and the chemical reactions of the excited state lead to the isolation of a phase that possesses a uranium isotopic distribution characteristic of enrichment, the uranium compound being the uranyl ion in the presence of at least one complexing ligand, the ligand being selected from the group consisting of CO/sub 3//sup 2 -/, O/sub 2//sup 2 -/, F/sup -/, Ch/sub 3/Coo/sup -/, C/sub 2/O/sub 4//sup 2 -/, and H/sub 2/O; (B) exciting the uranium compound in solution thus promoting the chemical reaction that preferentially forms the isolated phase containing the enriched uranium isotopic distribution the excitation involving photolysis of the complexed uranyl ion; and (C) separating the enriched phase thus recovering enriched uranium.

Peterson, S.H.; Phillips, D.C.

1986-01-28

422

Radiation-Chemical Behavior of Uranium in Ground Water  

Microsoft Academic Search

?-Radiolysis of aqueous solutions of mellitic acids (mellitic, pyromellitic, and trimellitic) simulating natural ground water was studied in the presence and absence of UO2 powder. It was found spectrophotometrically that in the absence of uranium dioxide with increasing irradiation dose the acid concentration decreases. At certain irradiation dose, specific for each mellitic acid, these acids are fully converted to carboxylic

D. A. Fedoseev; M. A. Dunaev; M. V. Vladimirova

2002-01-01

423

Magnesium bicarbonate as an in situ uranium lixiviant  

SciTech Connect

In the subsurface solution mining of mineral values, especially uranium, in situ, magnesium bicarbonate leaching solution is used instead of sodium, potassium and ammonium carbonate and bicarbonates. The magnesium bicarbonate solution is formed by combining carbon dioxide with magnesium oxide and water. The magnesium bicarbonate lixivant has four major advantages over prior art sodium, potassium and ammonium bicarbonates.

Sibert, J.W.

1984-09-25

424

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

425

Factors influencing the solution rate of uranium dioxide under conditions applicable to in situ leaching. Final report April 1977November 1978  

Microsoft Academic Search

This report presents the results of a study of controls on UO2 solution rate pertinent to lixiviants for in situ leaching operations. The report is divided into six sections: (1) discussion of the aqueous geochemistry of uranium applicable to leach studies; (2) brief outline of the kinetic concepts that have been considered in evaluating this and previous work; (3) review

R. Amell; D. Langmuir

1978-01-01

426

RAPID DETERMINATION OF TETRAVALENT URANIUM IN URANIUM TETRAFLUORIDE  

Microsoft Academic Search

A rapid and accurate analytical method is proposed for the titrimetric ; determination of U(IV) in uranium tetrafluoride. A sample weighing about 600 mg ; is treated with l0 ml of aluminum sulfate (2m)-sulfuric acid (6m) mixture and ; exactly 50 ml of 0.1 n potassium dichromate solution. By heating to 80 deg C for ; 10 to 20 min,

K. Motojima; H. Hashitani; K. Katsuyama

1961-01-01

427

Temperature programmed desorption characterization of oxidized uranium surfaces: Relation to some gas-uranium reactions  

SciTech Connect

The chemisorption characteristics and surface composition of oxidation overlayers developing on metals when exposed to oxidizing atmospheres are important in determining the protective ability of these layers against certain gas-phase reactions (e.g., corrosion and hydriding). In the present study, a special setup of supersonic molecular beam-temperature-programmed desorption was utilized to determine the different chemisorbed species present on oxidized uranium surfaces. The main identified species included water (in different binding forms) and hydrogen. The latter hydrogen originates from the water-uranium oxidation reaction, which produces uranium dioxide and two types of hydrogen: a near surface hydride and a surface-chemisorbed form that desorbs at a lower temperature than that of the hydride. Assignments of the different water desorption peaks to different binding sites were proposed. In general, four water desorption features were identified (labeled W{sub 0}, W{sub 1}, W{sub 2}, and W{sub 3}, respectively, in the order of increasing desorption temperatures). These features correspond to a reversibly chemisorbed molecular form (W{sub 0}), a more tightly bound water (chemisorbed on different type of oxide sites) or hydroxyl clusters (W{sub 1}), and strongly bounded (possibly isolated) hydroxyl groups (W{sub 2}). The highest temperature peak (W{sub 3}) is related to the formation of complex water-carbo-oxy compounds and is present only on oxidation overlayers, which contain proper chemisorbed carbo-oxy species. The relation of the water and hydrogen thermal release behavior to some problems addressed to certain effects observed in hydrogen-uranium and water-uranium reactions is discussed. For the latter, a microscopic mechanism is proposed.

Danon, A.; Koresh, J.E.; Mintz, M.H.

1999-08-31

428

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

429

ION EXCHANGE APPLIED TO RECOVERY OF URANIUM FROM SPRINGFIELDS CALCIUM FLUORIDE REACTION SLAG  

Microsoft Academic Search

Uraniferous liquor obtained by leaching Springfields' calcium fluoride ; reaction slag with 10% sulfuric acid containing manganese dioxide oxidizing agent ; was stripped of uranium by single column and multiple column ion exchange ; operations. The work was done on a laboratory scale using Dowex-1, a strong-base ; resin, in the nitrate form, which absorbs uranium as an anionic sulfate

Ware

1953-01-01

430

Intercomparison of reactive transport models applied to UO 2 oxidative dissolution and uranium migration  

Microsoft Academic Search

Oxidative dissolution of uranium dioxide (UO2) and the subsequent migration of uranium in a subsurface environment and an underground waste disposal have been simulated with reactive transport models. In these systems, hydrogeological and chemical processes are closely entangled and their interdependency has been analyzed in detail, notably with respect to redox reactions, kinetics of mineralogical evolution and hydrodynamic migration of

L. De Windt; A. Burnol; P. Montarnal; J. van der Lee

2003-01-01

431

Licensed Uranium Mills, Uranium Hexafluoride Production Plants, and Fuel Facilities: A Historical Review Through 1977.  

National Technical Information Service (NTIS)

This report is a historical review of currently licensed uranium mills, uranium hexafluoride production plants, and fuel facilities. Data are presented for each license on the licensing history, license amendment history, licensee event history, inspectio...

E. Touriguy

1978-01-01

432

Uranium in Nova Scotia: A Background Summary for the Uranium Inquiry, Nova Scotia.  

National Technical Information Service (NTIS)

Since the mid 1970's Nova Scotia has experienced increased exploration for a number of commodities including uranium. The exploration activity for uranium has resulted in discovery of significant occurrences of the element. It became obvious to the Govern...

1982-01-01

433

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

434

Depleted uranium disposal options evaluation  

SciTech Connect

The Department of Energy (DOE), Office of Environmental Restoration and Waste Management, has chartered a study to evaluate alternative management strategies for depleted uranium (DU) currently stored throughout the DOE complex. Historically, DU has been maintained as a strategic resource because of uses for DU metal and potential uses for further enrichment or for uranium oxide as breeder reactor blanket fuel. This study has focused on evaluating the disposal options for DU if it were considered a waste. This report is in no way declaring these DU reserves a ``waste,`` but is intended to provide baseline data for comparison with other management options for use of DU. To PICS considered in this report include: Retrievable disposal; permanent disposal; health hazards; radiation toxicity and chemical toxicity.

Hertzler, T.J.; Nishimoto, D.D.; Otis, M.D. [Science Applications International Corp., Idaho Falls, ID (United States). Waste Management Technology Div.

1994-05-01

435

Uranium-enrichment pricing policies  

SciTech Connect

Auditors found that the interest expense used in uranium enrichment pricing is based on the average rate Treasury pays on all Government issues outstanding, regardless of when they were issued, or for what purpose. Use of the Treasury's prevailing market rate would better ensure that enrichment prices more closely reflect actual costs incurred. Auditors also noted that in Fiscal Years 1979 through 1981, the interest charged on Government-owned feedstock added $515 million to enrichment costs, accounting for 32 percent of the Activity's interest costs and 12 percent of its total costs - costs that are passed on to customers in the form of higher prices. This was in response to a 1978 GAO recommendation. The Deputy Assistant Secretary for Uranium Enrichment and Assessment disagreed with the first finding but concurred in the second. His views are discussed.

Not Available

1983-07-06

436

Separation of zirconium and uranium. [Patent application  

SciTech Connect

This invention relates to separation and recovery of zirconium from aqueous solutions containing zirconium and uranium. Separation of zirconium from uranium is, however, difficult since the uranium tends to accompany the zirconium in the solvent extraction and stripping steps. It is therefore desirable, and an object of the invention, to provide a simple and economical way of removing a major portion of the zirconium from the zirconium and uranium-containing strip solutions, with minimal removal of uranium. It has now been found, according to the present invention, that such a removal of zirconium may be accomplished by means of a process involving precipitation of zirconium from such zirconium and uranium-containing feed solutions by means of tartaric acid or a tartrate.

Henry, H.G.

1981-05-27

437

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

438

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

439

Removal of uranium by biosorption  

Microsoft Academic Search

The technology developed here will exploit the ability of microorganisms to remove dissolved metals from aqueous solutions. Microbial sorbents for uranium will be immobilized biosorbents will be deployed ex situ within flow-through reactors for the continuous or semicontinuous treatment of recovered wastewaters. The proposed technology will primarily be applied within a pump-and-treat process using immobilized biosorbents for the large-scale, long-term

B. D. Faison; J. D. Bonner; N. D. Munroe; G. F. Bloomingburg

1993-01-01

440

Radiological hazards from uranium mining  

Microsoft Academic Search

\\u000a At all the French uranium mines where it made radiological surveys, the CRIIRAD laboratory discovered situations of environmental\\u000a contamination and a lack of proper protection of the inhabitants against health risks due to ionizing radiation. Radiological\\u000a problems are not only to be addressed during mining or milling operations but also on the longer term after mine closure.

Bruno Chareyron

441

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Highly Enriched Uranium (HEU). 540.306 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

2013-07-01

442

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Low Enriched Uranium (LEU). 540.308 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...Definitions § 540.308 Low Enriched Uranium (LEU). The term low enriched...

2013-07-01

443

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Highly Enriched Uranium (HEU). 540.306 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly enriched...

2009-07-01

444

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Low Enriched Uranium (LEU). 540.308 Section 540...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS...Definitions § 540.308 Low Enriched Uranium (LEU). The term low enriched...

2010-07-01

445

REMOVAL OF URANIUM FROM ORGANIC LIQUIDS  

DOEpatents

A process is described for recovering small quantities of uranium from organic liquids such as hydrocarbon oils. halogen-substituted hydrocarbons, and alcohols. The organic liquid is contacted with a comminuted alkaline earth hydroxide, calcium hydroxide particularly, and the resulting uranium-bearing solid is separated from the liquid by filtration. Uranium may then be recovered from the solid by means of dissolution in nitric acid and conventional extraction with an organic solvent such as tributyl phosphate.

Vavalides, S.P.

1959-08-25

446

Method of separating iron from uranium  

Microsoft Academic Search

In uranium recovery by solvent extraction processes, uranium is separated from iron in an organic extract by stripping the extract with a dilute aqueous solution containing carbonate ions, hydroxyl ions, and ammonium or alkali metal ions. The iron precipitates during stripping as FeO.nHO which is filtered off. The uranium is then precipitated from the filtrate as UO3.2H2O by steam stripping

Chiang

1981-01-01

447

EXTRACTION OF URANIUM FROM NATURAL WATER  

Microsoft Academic Search

As the result of hydrochemical studies it was found that in a number of ; the largest natural water sources the uranium content is 2.0 to 67 mg\\/m³. ; In some mine and oil waters the uranium concentration is 0.2 to 1.0 g\\/m³. ; The extraction of uranium from natural waters of different salt contents by means ; of mineral

B. N. Laskorin; S. S. Metalnikov; A. S. Terentiev

1959-01-01

448

Commercial considerations in enriched uranium transactions  

SciTech Connect

This article is the third in a series of articles on the commercial considerations of uranium transactions. Previous articles have dealt with UF6 and conversion services (February 1994), and U3O8 (March 1988). The present article focuses on the commercial considerations associated with enriched uranium and the enrichment process. Within this article are discussions of the specifications, handling and transport, and commercial transactions for enrichment and enriched uranium products.

Ruthowski, E.; White, G. Jr.

1995-03-01

449

ELECTROCHEMICAL DECONTAMINATION AND RECOVERY OF URANIUM VALUES  

DOEpatents

An electrochemical process is described for separating uranium from fission products. The method comprises subjecting the mass of uranium to anodic dissolution in an electrolytic cell containing aqueous alkali bicarbonate solution as its electrolyte, thereby promoting a settling from the solution of a solid sludge from about the electrodes and separating the resulting electrolyte solution containing the anodically dissolved uranium from the sludge which contains the rare earth fission products.

McLaren, J.A.; Goode, J.H.

1958-05-13

450

Immobilization of Uranium in Groundwater Using Biofilms  

Microsoft Academic Search

\\u000a Uranium is one of the most common radionuclides in soils, sediments, and groundwater at radionuclides-contaminated sites.\\u000a At these contaminated sites, uranium leaches into the groundwater, which has become a widespread problem at mining and milling\\u000a sites across North America, South America, and Eastern Europe. The movement of groundwater usually transports soluble uranium\\u000a contaminants beyond their original boundaries, causing a global

Bin Cao; Bulbul Ahmed; Haluk Beyenal

451

Systematic Analysis of Uranium Isotopes  

SciTech Connect

We describe recent nuclear model calculations and evaluations of neutron reactions on the uranium isotopes 232-241U in the keV to 30-MeV energy range. This work makes use of extensive sets of measurements for fission, elastic, inelastic (n,xn) and capture, as well as fission probability data. The 235U(n.f) standard cross section was revised, and the fission cross sections of the uranium isotopes, as well as 237Np and 239Pu, were updated using the revised standard. Nuclear reaction model calculations were performed for the whole suite of uranium isotopes to allow us to take advantage of the systematical properties from isotope-to-isotope, which is especially useful for nuclides where few measurements exist. In addition to improving the neutron cross sections and energy-angle distributions, new prompt fission neutron spectra and prompt/delayed neutron multiplicity evaluations are included for several isotopes. These evaluations are among the pre-ENDF/B-VII evaluations that are currently being considered for the new ENDF file. A companion paper in this Conference by MacFarlane describes critical-assembly integral data testing results for U isotopes.

Young, Phillip G.; Chadwick, Mark B.; MacFarlane, Robert E.; Madland, David G.; Moeller, Peter; Wilson, William B.; Talou, Patrick; Kawano, Toshihiko [T-16, Nuclear Physics Group, Los Alamos National Laboratory (United States)

2005-05-24

452

Uranium market issues and outlook  

SciTech Connect

The market for uranium has become increasingly international in scope. This trend is expected to continue, with additional sources of competitive supply entering the market. The decrease in constant-dollar uranium prices over the past 11-12 years has realigned competitive supply sources. Implementation of the US-Canada Free Trade Agreement in 1989 is a significant event in its implications for future trade patterns. Namibian independence from South Africa would open additional markets for Rossing production. Decisions by the government of Australia concerning the three mine policy and the floor price for contracts are crucial in the development of supply in that country. Uranium from China and the USSR may become increasingly available and acceptable to some worldwide buyers. Over the long run, the competitive status of the US with respect to certain foreign producers will probably depend more on the success of US producers in minimizing costs or using unconventional mining techniques, such as in-situ leach where feasible, than on legislative measures. Investment in promising areas outside of the US is a potential avenue to be explored for profitable ventures. Price formation is dependent on a number of interacting supply-and-demand factors. Future price movement will be the major factor determining which production centers will be competitive.

Julian, L.C. (Tennessee Valley Authority, Chattanooga (USA))

1989-09-01

453

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

454

Uranium and other contaminant migration in groundwater at a tropical Australian Uranium Mine  

Microsoft Academic Search

Hydrogeochemical modelling (utilising the modelling tools MODFLOW, MT3D and HARPHRQ) has been used in conjunction with laboratory-based experiments and a field monitoring program to investigate the fate of uranium and other contaminants in excess water sprayed on a 33 ha region of the Ranger Uranium Mine (RUM), northern Australia. The results indicate that uranium is retained in the surficial layer

Paul L Brown; Marianne Guerin; Stuart I Hankin; Richard T Lowson

1998-01-01

455

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

Microsoft Academic Search

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

Antonio Garralon; Paloma Gomez; Maria Jesus Turrero; Belen Buil; Lorenzo Sanchez

2007-01-01

456

Method for removing uranium-containing deposits in uranium hexafluoride processing equipment  

SciTech Connect

This invention pertains to a method for removing deposits of uranium compounds in uranium hexafluoride handling equipment. A fluorocarbon containing bromine is internally injected into the handling equipment at or below ambient pressure and this brominating agent removes uranium compounds which have been formed therein. A fluoridating agent is also preferably used in conjunction with the fluorocarbon containing bromine.

Bacher, W.; Jacob, E.

1982-01-19

457

Method for removing uranium-containing deposits in uranium hexafluoride processing equipment  

Microsoft Academic Search

This invention pertains to a method for removing deposits of uranium compounds in uranium hexafluoride handling equipment. A fluorocarbon containing bromine is internally injected into the handling equipment at or below ambient pressure and this brominating agent removes uranium compounds which have been formed therein. A fluoridating agent is also preferably used in conjunction with the fluorocarbon containing bromine.

W. Bacher; E. Jacob

1982-01-01

458

National Uranium Resource Evaluation program. Uranium geochemical survey in the Crystal City and Beeville Quadrangles, Texas  

Microsoft Academic Search

A uranium geochemical survey was conducted in the Crystal City and western half of the Beeville Quadrangles, Texas, an area of approximately 34,000 km². Using the Texas Gulf Coast Uranium Province as a study area, this survey demonstrates the applicability of a 2 phase hierarchical sampling program with multielement analysis of the samples for regional geochemical reconnaissance for uranium. Phase

C. E. Nichols; T. R. Butz; G. W. Cagle; V. E. Kane

1977-01-01

459

Possible uranium sources for the largest uranium district associated with volcanism: the Streltsovka caldera (Transbaikalia, Russia)  

Microsoft Academic Search

The uranium deposits of the Late Jurassic Streltsovka caldera (Transbaikalia, Russia) represent the largest uranium field associated with volcanics in the world (280,000 t U) and Russia's largest uranium resources. About one third of the caldera stratigraphic pile consists of rhyolites which are strongly altered. The rhyolitic magma preserved as melt inclusions in quartz phenocrysts corresponds to a mildly peralkaline

Aliouka Chabiron; Michel Cuney; Bernard Poty

2003-01-01

460

METHOD FOR DISSOLVING ZIRCONIUM-URANIUM COMPOSITIONS  

DOEpatents

A method is descrioed for treating a zirconium-- uranium composition to form a stable solution from which uranium and other values may be extracted by contacting the composition with at least a 4 molar aqueous solution of ammonium fluoride at a temperature of about 100 deg C, adding a peroxide, in incremental amounts, to the heated solution throughout the period of dissolution until all of the uranium is converted to soluble uranyl salt, adding nitric acid to the resultant solution to form a solvent extraction feed solution to convert the uranyl salt to a solvent extractable state, and thereafter recovering the uranium and other desired values from the feed solution by solvent extraction.

Gens, T.A.

1961-07-18

461

Liquid uranium reaction with coated graphite crucibles  

SciTech Connect

Carbon contamination in uranium from yttria-coated graphite crucibles containing uncoated defects has been measured at typical foundry melting conditions as a function of defect area. The reaction of liquid uranium with graphite at crucible coating defects is proportional to the defect surface area and is approx.270 times greater than the reaction at a coated region of equivalent area. Uranium carbon contamination is much more sensitive to coating defects than to furnace pressure, coating-graphite reaction, or binder outgassing. Although the typical contribution of coating defects is small, perturbations in production crucible loading or coating procedures could increase the defect area to produce uranium alloy castings with high carbon content.

Reiner, R.H.

1987-01-30

462

SEPARATION OF URANIUM, PLUTONIUM AND FISSION PRODUCTS  

DOEpatents

The separation of uranium and plutonium from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in nitric acid to provide an aqueous solution 3N in nitric acid. The fission products of the solution are extruded by treating the solution with dibutyl carbitol substantially 1.8N in nitric acid. The organic solvent phase is separated and neutralized with ammonium hydroxide and the plutonium reduced with hydroxylamine base to the trivalent state. Treatment of the mixture with saturated ammonium nitrate extracts the reduced plutonium and leaves the uranium in the organic solvent.

Nicholls, C.M.; Wells, I.; Spence, R.

1959-10-13

463

High strength and density tungsten-uranium alloys  

DOEpatents

Alloys of tungsten and uranium and a method for making the alloys. Amount of tungsten present in the alloys is from about 55 to 85. 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 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, H.

1991-12-31

464

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

465

77 FR 33782 - License Amendment To Construct and Operate New In Situ Leach Uranium Recovery Facility; Uranium...  

Federal Register 2010, 2011, 2012, 2013

...Amendment To Construct and Operate New In Situ Leach Uranium Recovery Facility; Uranium One Americas; Ludeman AGENCY: Nuclear Regulatory...referenced. The Ludeman facility In Situ Leach Uranium Recovery Project License Amendment Request is...

2012-06-07

466

Process of extracting both uranium and radium from uranium-containing ores  

SciTech Connect

Ferric chloride leaching at temperatures in the range 47-74/sup 0/C. is found to remove up to 97% of the uranium from ores occurring in the Elliot Lake area of Canada, but radium removal was found to be poor due to the formation of sulphates from the sulphides present in the ore. In processes of the invention the sulphides are initially removed by flotation, when aqueous acidic ferric chloride of relatively low concentration, e.g., 0.1 M can extract as much as 92% of the radium, giving tailings which are effectively sulphide-free and with radium levels approaching a desired maximum of 24 pCi/g. Radium may be removed by adsorption on manganese dioxide and uranium may be removed by liquid extraction with D2EHPA (DAPEX process). The ferric chloride may be recirculated for further leaching, with reduction before the uranium extraction and reoxidation afterwards. Because of the recycle, it is possible to keep chloride ion levels in the effluent below the prescribed level in Ontario, Canada of 750 ppm.

Nirdosh, I.; Baird, M.H.; Banerjee, S.; Muthuswami, S.V.

1984-06-12

467

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

468

Uptake of uranium, molybdenum, copper, and selenium by the radish from uranium-rich soils.  

PubMed

Radishes were grown in the naturally occurring uranium-containing soils found in the Okanagan Valley of British Columbia. The movement of uranium, molybdenum, copper, and selenium from the soil to the roots and the above-ground plant was investigated. Bioaccumulation was not observed for uranium, copper, and with some exceptions, selenium. Molybdenum bioaccumulates readily in the radish. Uranium and molybdenum uptake appears to be pH-dependent in this plant. Radish roots can be a significant source of uranium and molybdenum. Ingestion of radishes from these soils could easily surpass the maximum daily intake levels of uranium set by the Canadian government. Other crops and possible sources of uranium exposure around these deposits should be investigated. PMID:6870355

van Netten, C; Morley, D R

469

Canadian Experience with Uranium Tailings Disposal.  

National Technical Information Service (NTIS)

During the first years of uranium production in Canada uranium tailings were discharged directly into valleys or lakes near the mill. Treatment with barium chloride to precipitate radium began in 1965 at the Nordic Mine at Elliot Lake, Ontario. In the mid...

K. B. Culver

1982-01-01

470

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

471

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

472

National Uranium Resource Evaluation: Casper Quadrangle, Wyoming  

Microsoft Academic Search

The Casper Quadrangle, Wyoming, was evaluated for areas favorable for the occurrence of uranium deposits. Examination of surface exposures of known uranium occurrences, reconnaissance geochemical sampling, and ground radiometric surveys were conducted. Anomalous areas recognized from airborne radiometric surveys were ground checked. Electric and gamma logs were used to determine subsurface structure, stratigraphy, lithology, and areas of anomalous radioactivity. Fourteen

J. R. Griffin; E. J. Milton

1982-01-01

473

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

474

PROCESSES OF RECOVERING URANIUM FROM A CALUTRON  

Microsoft Academic Search

An improved process is described for recovering the residue of a uranium ; compound which has been subjected to treatment in a calutron, from the parts of ; the calutron disposed in the source region upon which the residue is deposited. ; The process may be utilized when the uranium compound adheres to a surface ; containing metals of the

D. O. Baird; L. R. Zumwalt

1958-01-01

475

PREPARATION OF ARC-MELTED URANIUM CARBIDES  

Microsoft Academic Search

Arc-melted uranium carbides are prepared for aluminum reactor fuel ; elements in which the U²³⁵ enrichment is limited to 20%. Aluminum-uranium ; carbide fuel plates, fabricated by the picture frame technique, retain their ; dimensional tolerance during heat treatment. Microstructures in color and in ; black and white were studied in detail. (auth);

R. J. Gray; W. C. Thurber; C. K. H. DuBose

1958-01-01

476

Chemical Properties of Uranium Hexafluoride, UF6  

Microsoft Academic Search

Uranium hexafluoride has the distinction of being the only stable gaseous compound of uranium known up to the present moment. Because of this property it is the only compound that can be used for processes of isotope separation, such as diffusion, thermal diffusion, centrifuge separation, distillation, and other of a similar nature. Here is a short description of the properties

Grosse; Aristid V

1941-01-01

477

Do diatom algae frustules accumulate uranium?  

Microsoft Academic Search

Neutron Activation Analysis (NAA) and Synchrotron Radiation X-ray Fluorescent Analysis (SRXRFA) were used to measure the content of uranium and a few other trace elements in samples of bottom sediments of Lake Baikel separated into biogenic (diatom algae frustules) and clastic components by an aerodynamic method. Uranium is rejected, rather than accumulated by diatom algae frustules.

E. L. Goldberg; M. A. Grachev; V. A. Bobrov; A. V. Bessergenev; B. V. Zolotaryov; Ye. V. Likhoshway

1998-01-01

478

The coprecipitation of uranium with calcium carbonate  

Microsoft Academic Search

This report is one of the studies on the factors controlling the trace element contents of marine calcareous skeletons. The values of the distribution coefficients of UO22+ between solutions and carbonate precipitates were measured in the laboratory at 201C. From the determination of the uranium contents of marine calcareous skeletons and sea water, the values of uranium between marine calcareous

Yasushi Kitano; Tamotsu Oomori

1971-01-01

479

The United States Uranium Industry, 1993  

Microsoft Academic Search

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

1993-01-01

480

Radiological aspects of in situ uranium recovery  

Microsoft Academic Search

In the last few years, there has been a significant increase in the demand for Uranium as historical inventories have been consumed and new reactor orders are being placed. Numerous mineralized properties around the world are being evaluated for Uranium recovery and new mining \\/ milling projects are being evaluated and developed. Ore bodies which are considered uneconomical to mine

STEVEN H

2007-01-01

481

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

482

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

483

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

484

OPERATION OF SMALL SCALE URANIUM REMOVAL SYSTEMS  

EPA Science Inventory

The design and Operation of a small full-scale ion exchange system used to remove uranium from well water in the foothills west of Denver, Colo., are described. onsistent removal of uranium was accomplished by anion exchange treatment at a reasonable cost. ecause of a lack of cle...

485

ENVIRONMENTAL OVERVIEW OF UNCONVENTIONAL EXTRACTION OF URANIUM  

EPA Science Inventory

Uranium mining areas in the United States are identified and briefly described, and the geologic, geochemical, and hydrologic factors associated with the various types of ore deposits are discussed. Uranium deposits that are now being mined or have recently been mined by solution...

486

The hydrofluorination of uranium and plutonium  

NASA Astrophysics Data System (ADS)

The preparation of uranium and plutonium deposits by vacuum deposition of their fluorides has a number of advantages over other methods, but requires anhydrous fluorides, which are preferably prepared using the dry hydrofluorination process. However this process depends on the way the starting materials have been prepared. Both for uranium and plutonium oxides preparation via the oxalate way is recommended.

Eykens, R.; Pauwels, J.; van Audenhove, J.

1985-06-01

487

An Estimate of India's Uranium Enrichment Capacity  

Microsoft Academic Search

Although the existence of India's uranium enrichment program has been known for a while, there is little technical information on the program available in the public domain. Here, we try to estimate its capacity based on the assumption that it has succeeded in producing sufficient enriched uranium for the core of the prototype reactor for the nuclear submarine that India

M. V. Ramana

2004-01-01

488

Radiometric Sorting of Rio Algom Uranium Ore.  

National Technical Information Service (NTIS)

An ore sample of about 0.2 percent uranium from Quirke Mine was subjected to radiometric sorting by Ore Sorters Limited. Approximately 60 percent of the sample weight fell within the sortable size range: -150 + 25 mm. Rejects of low uranium content (<0.01...

M. A. Cristovici

1983-01-01

489

National uranium resource evaluation: Nogales Quadrangle, Arizona  

Microsoft Academic Search

Literature research, surface geologic investigations, rock sampling, and radiometric surveys were conducted in the Nogales Quadrangle, Arizona, to identify environments and to delineate areas favorable for uranium deposits according to criteria formulated during the National Uranium Resource Evaluation program. The studies were augmented by aerial radiometric and hydrogeochemical and stream-sediment surveys. No favorable environments were identified. Environments that do display

R. H. Luning; L. A. Brouillard

1982-01-01

490

TERNARY ALLOYS OF URANIUM, COLUMBIUM, AND ZIRCONIUM  

DOEpatents

Ternary alloys of uranium are described which are useful as neutron- reflecting materials in a fast neutron reactor. They are especially resistant to corrosion caused by oxidative processes of gascous or aqueous origin and comprise uranium as the predominant metal with zirconiunn and niobium wherein the total content of the minor alloying elements is between 2 and 8% by weight.

Foote, F.G.

1960-08-01

491

Health concerns in uranium mining and milling  

Microsoft Academic Search

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

Victor E. Archer

1981-01-01

492

Modeled atmospheric radon concentrations from uranium mines  

Microsoft Academic Search

Uranium mining and milling operations result in the release of radon from numerous sources of various types and strengths. The US Environmental Protection Agency (EPA) under the Clean Air Act, is assessing the health impact of air emissions of radon from underground uranium mines. In this case, the radon emissions may impact workers and residents in the mine vicinity. To

Droppo

1985-01-01

493

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

494

PROCESSES OF RECOVERING URANIUM FROM A CALUTRON  

DOEpatents

An improved process is described for recovering the residue of a uranium compound which has been subjected to treatment in a calutron, from the parts of the calutron disposed in the source region upon which the residue is deposited. The process may be utilized when the uranium compound adheres to a surface containing metals of the group consisting of copper, iron, chromium, and nickel. The steps comprise washing the surface with an aqueous acidic oxidizing solvent for the uranium whereby there is obtained an acidic aqueous Solution containing uranium as uranyl ions and metals of said group as impurities, treating the acidic solution with sodium acetate in the presenee of added sodium nitrate to precipitate the uranium as sodium uranyl acetate away from the impurities in the solution, and separating the sodium uranyl acetate from the solution.

Baird, D.O.; Zumwalt, L.R.

1958-07-15

495

Mica Surfaces Stabilize Pentavalent Uranium  

SciTech Connect

We used high-resolution x-ray photoelectron spectroscopy to demonstrate that reduction of aqueous U6+ at ferrous mica surfaces at 25oC preserves U5+ as the dominant sorbed species over a broad range of solution compositions. Polymerization of sorbed U5+ with sorbed U6+ and U4+ is identified as a possible mechanism for how mineral surfaces circumvent the rapid disproportionation of aqueous U5+. The general nature of this mechanism suggests that U5+ could play an important, but previously unidentified, role in the lowtemperature chemistry of uranium in reducing, heterogeneous aqueous systems.

Ilton, Eugene S.; Haiduc, Anca; Cahill, Christopher L.; Felmy, Andrew R.

2005-05-02

496

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

PubMed

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 concentration in the soil solution or uranium recovered by ammonium acetate. Ryegrass (Lolium perenne L. var. Melvina) is grown in greenhouse on a range of uranium spiked soils. The DGT-recovered uranium concentration (C(DGT)) was correlated with uranium concentration in the soil solution or with uranium recovered by ammonium acetate extraction. Plant uptake was better predicted by the summed soil solution concentrations of UO(2)(2+), uranyl carbonate complexes and UO(2)PO(4)(-). The DGT technique did not provide significant advantages over conventional methods to predict uranium uptake by plants. PMID:19822385

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

2009-10-12

497

RADIOLOGICAL PROTECTION OF WORKERS ENGAGED IN THE MANUFACTURE OF NATURAL URANIUM FUEL AT THE SPRINGFIELDS' FACTORY OF THE U.K.A.E.A  

Microsoft Academic Search

The Works manufactures uranium metal from ore concentrates and sheaths ; it in aluminum and magnesium alloy. Uranium hexafluoride is also manufactured ; from pile-depleted uranyl nitrate. There are laboratories engaged in physical ; and chemical research in addition to chemical and metallurgical plants. ; Processes include solvent extraction of uranyl nitrate, hydrofluorination of ; uranium dioxide, magnesium reduction of

A. Butterworth; A. Cook; H. Mason

1959-01-01

498

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

499

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

500

Mortality among Navajo uranium miners.  

PubMed Central

OBJECTIVES. To update mortality risks for Navajo uranium miners, a retrospective cohort mortality study was conducted of 757 Navajos from the cohort of Colorado Plateau uranium miners. METHODS. Vital status was followed from 1960 to 1990. Standardized mortality ratios were estimated, with combined New Mexico and Arizona non-White mortality rates used for comparison. Cox regression models were used to evaluate exposure-response relationships. RESULTS. Elevated standardized mortality ratios were found for lung cancer (3.3), tuberculosis (2.6), and pneumoconioses and other respiratory diseases (2.6). Lowered ratios were found for heart disease (0.6), circulatory disease (0.4), and liver cirrhosis (0.5). The estimated relative risk for a 5-year duration of exposure vs none was 3.7 for lung cancer, 2.1 for pneumoconioses and other respiratory diseases, and 2.0 for tuberculosis. The relative risk for lung cancer was 6.9 for the midrange of cumulative exposure to radon progeny compared with the least exposed. CONCLUSIONS. Findings were consistent with those from previous studies. Twenty-three years after their last exposure to radon progeny, these light-smoking Navajo miners continue to face excess mortality risks from lung cancer and pneumoconioses and other respiratory diseases.

Roscoe, R J; Deddens, J A; Salvan, A; Schnorr, T M

1995-01-01