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1

Uranium dioxide electrolysis  

DOEpatents

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

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

2009-12-29

2

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

Microsoft Academic Search

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,

Charles Burnett Yeamans

2008-01-01

3

Dry process fluorination of uranium dioxide using ammonium bifluoride  

E-print Network

An experimental study was conducted to determine the practicality of various unit operations for fluorination of uranium dioxide. The objective was to prepare ammonium uranium fluoride double salts from uranium dioxide and ...

Yeamans, Charles Burnett, 1978-

2003-01-01

4

Conversion of Uranium Oxide into Nitrate with Nitrogen Dioxide  

Microsoft Academic Search

In order to decrease the amount of aqueous liquid waste discharged from nuclear fuel reprocessing, the conversion of uranium dioxide into its nitrate using liquefied nitrogen dioxide was studied. Uranium dioxide powder was immersed in liquefied nitrogen dioxide at 313 K after a pretreatment by the oxidation of the uranium dioxide with nitrogen dioxide and air at 523 K. Seventy-nine

Kayo Sawada; Daisuke Hirabayashi; Youichi Enokida; Ichiro Yamamoto

2008-01-01

5

Uranium  

SciTech Connect

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

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

2006-07-31

6

Uranium*  

NASA Astrophysics Data System (ADS)

Uranium compounds have been used as colorants since Roman times (Caley, 1948). Uranium was discovered as a chemical element 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 mineral to be a complex oxide of iron and tungsten or of iron and zinc, but Klaproth showed by dissolving it partially in strong acid that the solutions yielded precipitates that were different from those of known elements. Therefore he concluded that it contained a new element (Mellor, 1932); he named it after the planet Uranus, which had been discovered in 1781 by William Herschel, who named it after the ancient Greek deity of the Heavens.

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

7

Conversion of Uranium Oxide into Nitrate with Nitrogen Dioxide  

NASA Astrophysics Data System (ADS)

In order to decrease the amount of aqueous liquid waste discharged from nuclear fuel reprocessing, the conversion of uranium dioxide into its nitrate using liquefied nitrogen dioxide was studied. Uranium dioxide powder was immersed in liquefied nitrogen dioxide at 313 K after a pretreatment by the oxidation of the uranium dioxide with nitrogen dioxide and air at 523 K. Seventy-nine % of the uranium dioxide, whose initial feed amount was 0.3 g, was converted into a water soluble compound. Based on an XRD analysis of the compound, uranyl nitrate trihydrate (UO2(NO3)23H2O) was confirmed.

Sawada, Kayo; Hirabayashi, Daisuke; Enokida, Youichi; Yamamoto, Ichiro

8

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

9

Uranium dioxide dissolution under acidic aqueous conditions  

SciTech Connect

Understanding of the long-term dissolution of waste forms in groundwater is required for the safe disposal of high level nuclear waste in a geologic repository, because waste-form radionuclides could be released by dissolution and transported in groundwater. The dissolution of the uranium dioxide (UO{sub 2}) matrix in spent nuclear fuel is considered the rate-limiting step for release of radioactive fission products. The intrinsic UO{sub 2} dissolution rate sets an upper limit on the aqueous radionuclide release rate. Unsaturated spent fuel tests have shown that pH`s of leachates have decreased to a range of 4 to 6, presumably due to air radiolysis that oxidizes nitrogen, producing nitric acid. Dissolution rates under such acidic conditions may be different than those previously reported for alkaline groundwater conditions. No dissolution rate measurements of UO{sub 2} or spent fuel have been reported for acidic conditions possibly relevant to a geologic repository. The purpose of our work has been to measure the intrinsic dissolution rates of uranium dioxide under acidic conditions that are relevant to a repository and allow for modeling. Experiments have been completed at room-temperature and 75 C, pH`s of 4 and 6, and air and oxygen saturated aqueous solutions. These are compared with earlier work on spent fuel and UO{sub 2} using alkaline solutions.

Steward, S.A.; Mones, E.T.

1995-11-20

10

Molecular dynamics analysis of diffusion of uranium and oxygen ions in uranium dioxide  

Microsoft Academic Search

Diffusion behaviours of oxygen and uranium were evaluated for bulk and grain-boundaries of uranium dioxide using the molecular dynamics (MD) simulation. It elucidated that oxygen behaved like liquid in superionic state at high temperatures and migrated on sub-lattice sites accompanying formation of lattice defects such as Frenkel defects at middle temperatures. Formation energies of Frenkel and Shottky defects were compared

T. Arima; K. Yoshida; K. Idemitsu; Y. Inagaki; I. Sato

2010-01-01

11

Molten uranium dioxide structure and dynamics.  

PubMed

Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts. PMID:25414311

Skinner, L B; Benmore, C J; Weber, J K R; Williamson, M A; Tamalonis, A; Hebden, A; Wiencek, T; Alderman, O L G; Guthrie, M; Leibowitz, L; Parise, J B

2014-11-21

12

Molecular dynamics analysis of diffusion of uranium and oxygen ions in uranium dioxide  

NASA Astrophysics Data System (ADS)

Diffusion behaviours of oxygen and uranium were evaluated for bulk and grain-boundaries of uranium dioxide using the molecular dynamics (MD) simulation. It elucidated that oxygen behaved like liquid in superionic state at high temperatures and migrated on sub-lattice sites accompanying formation of lattice defects such as Frenkel defects at middle temperatures. Formation energies of Frenkel and Shottky defects were compared to literature data, and migration energies of oxygen and uranium were estimated by introducing vacancies into the supercell. For grain-boundaries (GB) modelled by the coincidence-site lattice theory, MD calculations showed that GB energy and diffusivities of oxygen and uranium increased with the misorientation angle. By analysing GB structures such as pair-correlation functions, it also showed that the disordered phase was observed for uranium as well as oxygen in GBs especially for a large misorientation angle such as S5 GB. Hence, GB diffusion was much larger than bulk diffusion for oxygen and uranium.

Arima, T.; Yoshida, K.; Idemitsu, K.; Inagaki, Y.; Sato, I.

2010-03-01

13

Oxygen diffusion in hypostoichiometric uranium dioxide  

SciTech Connect

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

Kim, K.C.

1980-12-01

14

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 UO 2.

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

2010-07-01

15

Surface blistering and flaking of sintered uranium dioxide samples under high dose gas implantation and annealing  

E-print Network

Surface blistering and flaking of sintered uranium dioxide samples under high dose gas implantation-sur-Yvette, France. a guillaume.martin@cea.fr Keywords: uranium dioxide, helium, hydrogen, implantation, blistering, flaking Abstract. High helium contents will be generated within minor actinide doped uranium dioxide

Boyer, Edmond

16

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

17

Simulation of diffusion of oxygen and uranium in uranium dioxide nanocrystals  

NASA Astrophysics Data System (ADS)

The method of molecular dynamics is used to study phase transitions and ion transport phenomena in uranium dioxide nanocrystals. The temperature dependences of uranium and oxygen diffusion coefficients in the range from 2280 to 3950 K are calculated separately for surface, near-surface and bulk regions of the crystals. On these dependences we have distinguished temperature intervals, which correspond to crystalline phase, superionic state and melt. The activation energies of diffusion and pre-exponential factors for these intervals are determined. The obtained results are compared with experimental data and calculations of other authors.

Kupryazhkin, A. Ya.; Zhiganov, A. N.; Risovany, D. V.; Nekrassov, K. A.; Risovany, V. D.; Golovanov, V. N.

2008-01-01

18

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

NASA Astrophysics Data System (ADS)

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 from the standard deviation of the force constant used for the calculation, which is about 5%. at 0C, 2%. at 200C and 0.2%. at 1000C for both oxides. The r.p.f.r. for both uranium oxides are lower than that of water, implying that uraninite is depleted in 18O with respect to associated fluids at almost all temperature ranges. The fractionation factors between uranium oxides and water are expressed as: 10 3 ln ? = 3.29 10 6/T 2-13.63 10 3/T + 4.65 , and 10 3 ln ? = 3.63 10 6/T 2-13.29 10 3/T + 4.42 for ?-UO 3 and UO 2, respectively. The values of r.p.f.r. for uranium oxides are low compared to those for common rock-forming minerals, however they are similar to the values for other metal oxides, such as magnetite, rutile and probably cassiterite.

Hattori, Keiko; Halas, Stanislaw

1982-10-01

19

Diffusion model of the non-stoichiometric uranium dioxide  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

20

Point defects in uranium dioxide: Ab initio pseudopotential approach in the generalized gradient approximation  

NASA Astrophysics Data System (ADS)

The stability of point defects in uranium dioxide is studied using an ab initio plane wave pseudopotential method in the generalized gradient approximation of the density functional theory. Uranium pseudopotentials are first tested in both the generalized gradient approximation and the local density approximation on metallic phases of uranium and on uranium dioxide. It is found that the generalized gradient approximation gives the best description of these materials. The energies of formation of point defects (single vacancies and interstitials, Frenkel pairs and Schottky defects) in UO 2 are calculated. The values obtained lead to a reliable set of numerical data that are analyzed in the framework of the point defect model commonly used to assess defect concentrations in uranium dioxide as a function of the stoichiometry. The ability of the point defect model to accurately reproduce defect concentrations in uranium dioxide is discussed.

Freyss, Michel; Petit, Thierry; Crocombette, Jean-Paul

2005-12-01

21

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

Microsoft Academic Search

The results of a 2-yr effort to determine the capability of U.S. fuel manufacturers to economically manufacture thorium-uranium dioxide (ThO-UO) fuel in plants that have previously only manufactured UO fuel with <5% ²³⁵U 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

Lahoda; Edward J

2004-01-01

22

Refinement in the ultrasonic velocity data and estimation of the critical parameters for molten uranium dioxide  

E-print Network

uranium dioxide Abdul-Majeed Azad * Department of Chemical and Environmental Engineering, The University, reliable data on the sound prop- agation velocity in molten uranium dioxide have been obtained. An equation reserved. 1. Introduction The analysis of hypothetical and undesirable yet highly improbable accidents

Azad, Abdul-Majeed

23

Standard test methods for analysis of sintered gadolinium oxide-uranium dioxide pellets  

E-print Network

1.1 These test methods cover procedures for the analysis of sintered gadolinium oxide-uranium dioxide pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Section Carbon (Total) by Direct CombustionThermal Conductivity Method C1408 Test Method for Carbon (Total) in Uranium Oxide Powders and Pellets By Direct Combustion-Infrared Detection Method Chlorine and Fluorine by Pyrohydrolysis Ion-Selective Electrode Method C1502 Test Method for Determination of Total Chlorine and Fluorine in Uranium Dioxide and Gadolinium Oxide Gadolinia Content by Energy-Dispersive X-Ray Spectrometry C1456 Test Method for Determination of Uranium or Gadolinium, or Both, in Gadolinium Oxide-Uranium Oxide Pellets or by X-Ray Fluorescence (XRF) Hydrogen by Inert Gas Fusion C1457 Test Method for Determination of Total Hydrogen Content of Uranium Oxide Powders and Pellets by Carrier Gas Extraction Isotopic Uranium Composition by Multiple-Filament Surface-Ioni...

American Society for Testing and Materials. Philadelphia

2006-01-01

24

Immobilization of chlorine dioxide modified cells for uranium absorption.  

PubMed

There has been a trend towards the use of microorganisms to recover metals from industrial wastewater, for which various methods have been reported to be used to improve microorganism adsorption characteristics such as absorption capacity, tolerance and reusability. In present study, chlorine dioxide(ClO2), a high-efficiency, low toxicity and environment-benign disinfectant, was first reported to be used for microorganism surface modification. The chlorine dioxide modified cells demonstrated a 10.1% higher uranium adsorption capacity than control ones. FTIR analysis indicated that several cell surface groups are involved in the uranium adsorption and cell surface modification. The modified cells were further immobilized on a carboxymethylcellulose(CMC) matrix to improve their reusability. The cell-immobilized adsorbent could be employed either in a high concentration system to move vast UO2(2+) ions or in a low concentration system to purify UO2(2+) contaminated water thoroughly, and could be repeatedly used in multiple adsorption-desorption cycles with about 90% adsorption capacity maintained after seven cycles. PMID:24998748

He, Shengbin; Ruan, Binbiao; Zheng, Yueping; Zhou, Xiaobin; Xu, Xiaoping

2014-11-01

25

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

26

Chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade uranium dioxide powders and pellets  

SciTech Connect

Uranium dioxide is used as a nuclear-reactor fuel. In order to be suitable for this purpose, the material must meet certain criteria for uranium content, stoichiometry, isotopic composition, impurity content. The following analytical procedures, which are described in detail, are designed to show whether or not a given material meets specifications: uranium by ferrous sulfate reduction in phosphoric acid and dichromate titration method; uranium and oxygen uranium atomic ratio by the ignition (gravimetric) impurity correction method; oxygen to uranium atomic ratios by the polarographic method; carbon (total) by direct combustion-thermal conductivity method; total chlorine and fluorine by pyrohydrolysis ion-selective electrode method; moisture by the coulometric, electrolytic moisture analyzer method; nitrogen by the Kjeldahl method; total sulfur by distillation-spectrophotometric method; isotopic uranium composition by multiple-filament surface-ionization mass spectrometric method; spectrochemical determination of trace elements in high-purity uranium dioxide; volatile fluoride impurities by spectrochemical method using the rotating-disk spark technique; spectrochemical determination of silver by gallium oxide carrier D-C arc technique; rare earths by copper spark-spectrochemical method; impurity elements by a spark-source mass spectrographic method; surface area by nitrogen absorption method; total gas in reactor-grade uranium dioxide pellets; thorium and rare earth elements by spectroscopy; hydrogen by inert gas fusion; and uranium isotopic analysis by mass spectrometry. (JMT)

Not Available

1981-01-01

27

Irradiation of TZM: Uranium dioxide fuel pin at 1700 K  

NASA Technical Reports Server (NTRS)

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

Mcdonald, G. E.

1973-01-01

28

Elementary excitations in uranium dioxide: Unravelling the tangle  

NASA Astrophysics Data System (ADS)

In solids with d- and f-electrons, under certain conditions the orbitals align to form an ordered structure. Collective excitations breaking this arrangement can take the form of oscillations of electric quadrupoles, the so-called quadrupolar waves. These represent a propagating pattern of charge densities implying a modulation of quadrupolar moments. Quadrupolar waves constitute a major component of the dynamics of uranium dioxide in its magneto-quadrupolar ordered phase. Together with spin-waves and phonons, these produce a very complex spectrum of elementary excitations having hybrid character over most of the Brillouin zone. Although neutron scattering spectra only reveal the tip of the iceberg of this spectrum, its complete and detailed modelling is needed to understand such experiments. Distinct roles of Jahn-Teller and superexchange mechanisms as sources of quadrupolar interactions can be clearly identified by such modelling. xml:lang="fr"

Santini, Paolo

2014-08-01

29

High temperature behavior of metallic inclusions in uranium dioxide  

SciTech Connect

The object of this thesis was to construct a temperature gradient furnace to simulate the thermal conditions in the reactor fuel and to study the migration of metallic inclusions in uranium oxide under the influence of temperature gradient. No thermal migration of molybdenum and tungsten inclusions was observed under the experimental conditions. Ruthenium inclusions, however, dissolved and diffused atomically through grain boundaries in slightly reduced uranium oxide. An intermetallic compound (probably URu/sub 3/) was formed by reaction of Ru and UO/sub 2-x/. The diffusivity and solubility of ruthenium in uranium oxide were measured.

Yang, R.L.

1980-08-01

30

Standard test method for the determination of uranium by ignition and the oxygen to uranium (O/U) atomic ratio of nuclear grade uranium dioxide powders and pellets  

E-print Network

1.1 This test method covers the determination of uranium and the oxygen to uranium atomic ratio in nuclear grade uranium dioxide powder and pellets. 1.2 This test method does not include provisions for preventing criticality accidents or requirements for health and safety. Observance of this test method does not relieve the user of the obligation to be aware of and conform to all international, national, or federal, state and local regulations pertaining to possessing, shipping, processing, or using source or special nuclear material. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.4 This test method also is applicable to UO3 and U3O8 powder.

American Society for Testing and Materials. Philadelphia

2000-01-01

31

A thermal modelling of displacement cascades in uranium dioxide  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

32

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

33

Studies on the sintering behaviour of uranium dioxide powder compacts  

NASA Astrophysics Data System (ADS)

Uranium dioxide fuel pellets are normally made from their precursor ammonium diuranate, followed by calcination, subsequent reduction to sinterable grade powders and a post operation treatment of pressing and sintering. The low temperature calcined powders, usually exhibiting non-crystalline behaviour (under X-ray diffraction studies) progressively transforms into a crystalline variety on subsequent heat treatment at higher temperature. It is observed however that powders calcined between 800 to 900C exhibit enhanced densification behaviour when sintered at higher temperatures. The isothermal shrinkage versus time plot of the sintered compacts are well described by a hyperbolic relationship which takes care of the observed shrinkage (?) as caused due to a cumulative effect from the initial sintering of the powder compacts at zero time (?) and that caused due to the structural transformation from a non-crystalline modification with increased thermal treatment (?). The derived equation is a modification of the sintering mechanism of the viscous flow type proposed by Frenkel, involving sintering of an amorphous phase, the viscosity of the latter is presumed to increase with increasing thermal treatment to assume the final modified form as ? = {t}/{(? +?t)}, where t = time, ? = shrinkage and ? and ? are the unknown parameters.

Das, Pranab; Chowdhury, Ranjit

1988-09-01

34

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

35

Heavy Ion Beam in Resolution of the Critical Point Problem for Uranium and Uranium Dioxide  

E-print Network

Important advantages of heavy ion beam (HIB) irradiation of matter are discussed in comparison with traditional sources - laser heating, electron beam, electrical discharge etc. High penetration length (~ 10 mm) is of primary importance for investigation of dense matter properties. This gives an extraordinary chance to reach the uniform heating regime when HIB irradiation is being used for thermophysical property measurements. Advantages of HIB heating of highly-dispersive samples are claimed for providing free and relatively slow quasi-isobaric heating without fast hydrodynamic expansion of heated sample. Perspective of such HIB application are revised for resolution of long-time thermophysical problems for uranium and uranium-bearing compounds (UO2). The priorities in such HIB development are stressed: preferable energy levels, beam-time duration, beam focusing, deposition of the sample etc.

Iosilevskiy, Igor

2010-01-01

36

Heavy Ion Beam in Resolution of the Critical Point Problem for Uranium and Uranium Dioxide  

E-print Network

Important advantages of heavy ion beam (HIB) irradiation of matter are discussed in comparison with traditional sources - laser heating, electron beam, electrical discharge etc. High penetration length (~ 10 mm) is of primary importance for investigation of dense matter properties. This gives an extraordinary chance to reach the uniform heating regime when HIB irradiation is being used for thermophysical property measurements. Advantages of HIB heating of highly-dispersive samples are claimed for providing free and relatively slow quasi-isobaric heating without fast hydrodynamic expansion of heated sample. Perspective of such HIB application are revised for resolution of long-time thermophysical problems for uranium and uranium-bearing compounds (UO2). The priorities in such HIB development are stressed: preferable energy levels, beam-time duration, beam focusing, deposition of the sample etc.

Igor Iosilevskiy; Victor Gryaznov

2010-05-23

37

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

38

Advanced, lower-cost, proliferation-resistant, uranium-thorium dioxide fuels for LWRs  

Microsoft Academic Search

The overall 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 (UO) fuel, (b) allows longer refueling cycles and higher sustainable plant capacity factors, (c) is very resistant to nuclear weapons-material proliferation, (d) results in a more stable and insoluble waste form, and (e) generates

J. S. Herring; P. E. MacDonald

1999-01-01

39

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

40

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

41

Energy calibrations in the x-ray absorption spectroscopy of uranium dioxide  

SciTech Connect

Proper and accurate placement of the components of the unoccupied density of states in uranium dioxide requires a careful calibration of the energy scales in the spectroscopic investigations. Here, the energy scale calibrations and corresponding spectroscopic measurements are described in detail, including photoelectron spectroscopy, inverse photoelectron spectroscopy and, most important, x-ray absorption spectroscopy.

Yu, Sung Woo; Tobin, J. G.; Olalde-Velasco, Paul; Yang, Wan Li; Siekhaus, Wigbert J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 and Instituto de Ciencias Nucleares, UNAM, Distrito Federal 04510 (Mexico); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-01-15

42

Continuous process for the production of powdered uranium dioxide from uranyl nitrate  

SciTech Connect

A method is described of producing uranium dioxide powder for the fabrication of nuclear fuel from acidic solutions containing uranyl nitrate, comprising the sequence of steps of: (a) continuously reacting an acidic aqueous solution of uranyl nitrate with ammonium hydroxide added in less than stoichiometric amount for complete uranium precipitation, neutralizing any free acid and precipitating a portion of the uranium content of the solution as ammonium uranate solids; (b) continuously aging the product resulting from reacting the uranyl nitrate of the solution with less than a stoichiometric amount of ammonium hydroxide, including the precipitated ammonium uranate solids while maintaining the solids substantially suspended in the medium of the aqueous solution; (c) thereafter continuously reacting the aged product comprising uranyl nitrate and precipitated ammonium uranate with additional added ammonium hydroxide in amount at least sufficient to complete the precipitation of the uranium of the solution as ammonium uranate solids; and (e) calcining the dewatered ammonium uranate solids in a reducing atmosphere and thereby converting the ammonium uranate solids in a reducing atmosphere and thereby converting the ammonium uranate to uranium dioxide powder.

Divins, L.A.; Runion, H.L.

1987-04-07

43

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

44

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

45

Etching of uranium dioxide in nitrogen trifluoride RF plasma glow discharge  

Microsoft Academic Search

A series of room temperature, low pressure (10.8 to 40 Pa), low power (25 to 210 W) RF plasma glow discharge experiments with UO2 were conducted to demonstrate that plasma treatment is a viable method for decontaminating UO2 from stainless steel substrates. Experiments were conducted using NF3 gas to decontaminate depleted uranium dioxide from stainless-steel substrates. Results demonstrated that UO2

John Mark Veilleux

1999-01-01

46

Depleted Uranium  

MedlinePLUS

... Toll Free Numbers VA Health Care Public Health Military Exposures Depleted Uranium Public Health Public Health Public Health Home Military Exposures Military Exposures Home 4 Ways to Find ...

47

THERMODYNAMIC MODEL FOR URANIUM DIOXIDE BASED NUCLEAR FUEL  

SciTech Connect

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

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

2007-01-01

48

Interplay of defect cluster and the stability of xenon in uranium dioxide from density functional calculations  

NASA Astrophysics Data System (ADS)

Self-defect clusters in bulk matrix might affect the thermodynamic behavior of fission gases in nuclear fuel such as uranium dioxide. With first-principles local spin-density approximation plus U calculations and taking xenon as a prototype, we find that the influence of oxygen defect clusters on the thermodynamics of gas atoms is prominent, which increases the solution energy of xenon by a magnitude of 0.5 eV, about 43% of the energy difference between the two lowest lying states at 700 K. Calculation also reveals a thermodynamic competition between the uranium vacancy and trivacancy sites to incorporate xenon in hyperstoichiometric regime at high temperatures. The results show that in hypostoichiometric regime neutral trivacancy sites are the most favored position for diluted xenon gas, whereas in hyperstoichiometric condition they prefer to uranium vacancies even after taking oxygen self-defect clusters into account at low temperatures, which not only confirms previous studies but also extends the conclusion to more realistic fuel operating conditions. The observation that gas atoms are ionized to a charge state of Xe+ when at a uranium vacancy site due to strong Madelung potential implies that one can control temperature to tune the preferred site of gas atoms and then the bubble growth rate. A solution to the notorious metastable states difficulty that frequently encountered in density functional theory plus U applications, namely, the quasiannealing procedure, is also discussed.

Geng, Hua Y.; Chen, Ying; Kaneta, Yasunori; Kinoshita, Motoyasu; Wu, Q.

2010-09-01

49

Uranium reduction.  

PubMed

The dramatic decrease in solubility accompanying the reduction of U(VI) to U(IV), producing the insoluble mineral uraninite, has been viewed as a potential mechanism for sequestration of environmental uranium contamination. In the past 15 years, it has been firmly established that a variety of bacteria exhibit this reductive capacity. To obtain an understanding of the microbial metal metabolism, to develop a practical approach for the acceleration of in situ bioreduction, and to predict the long-term fate of environmental uranium, several aspects of the microbial process have been experimentally explored. This review briefly addresses the research to identify specific uranium reductases and their cellular location, competition between uranium and other electron acceptors, attempts to stimulate in situ reduction, and mechanisms of reoxidation of reduced uranium minerals. PMID:16704344

Wall, Judy D; Krumholz, Lee R

2006-01-01

50

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

SciTech Connect

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

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

2014-01-01

51

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

E-print Network

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 poi...

Geng, Hua Y; Jin, K; Xiang, S K; Wu, Q

2011-01-01

52

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

53

Microbeam x-ray absorption spectroscopy study of chromium in large-grain uranium dioxide fuel  

NASA Astrophysics Data System (ADS)

Synchrotron-based microprobe x-ray absorption spectroscopy (XAS) has been used to study the local atomic structure of chromium in chromia-doped uranium dioxide (UO2) grains. The specimens investigated were a commercial grade chromia-doped UO2 fresh fuel pellet, and materials from a spent fuel pellet of the same batch, irradiated with an average burnup of ~40?MW d kg-1. Uranium L3-edge and chromium K-edge XAS have been measured, and the structural environments of central uranium and chromium atoms have been elucidated. The Fourier transform of uranium L3-edge extended x-ray absorption fine structure shows two well-defined peaks of U-O and U-U bonds at average distances of 2.36 and 3.83?. Their coordination numbers are determined as 8 and 11, respectively. The chromium Fourier transform extended x-ray absorption fine structure of the pristine UO2 matrix shows similar structural features with the corresponding spectrum of the irradiated spent fuel, indicative of analogous chromium environments in the two samples studied. From the chromium XAS experimental data, detectable next neighbor atoms are oxygen and uranium of the cation-substituted UO2 lattice, and two distinct subshells of chromium and oxygen neighbors, possibly because of undissolved chromia particles present in the doped fuels. Curve-fitting analyses using theoretical amplitude and phase-shift functions of the closest Cr-O shell and calculations with ab initio computer code FEFF and atomic clusters generated from the chromium-dissolved UO2 structure have been carried out. There is a prominent reduction in the length of the adjacent Cr-O bond of about 0.3? in chromia-doped UO2 compared with the ideal U-O bond length in standard UO2 that would be expected because of the change in effective Coulomb interactions resulting from replacing U4+ with Cr3+ and their ionic size differences. The contraction of shortest Cr-U bond is ~0.1? relative to the U-U bond length in bulk UO2. The difference in the local chromium environment between fresh and irradiated UO2 is discussed based on the comparison of quantitative structural information obtained from the two chromia-doped fuel samples analyzed.

Mieszczynski, C.; Kuri, G.; Bertsch, J.; Martin, M.; Borca, C. N.; Delafoy, Ch; Simoni, E.

2014-09-01

54

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

55

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

56

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

57

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

58

Uranium industry annual, 1991  

SciTech Connect

In the Uranium Industry Annual 1991, data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2. A feature article entitled ``The Uranium Industry of the Commonwealth of Independent States`` is included in this report.

Not Available

1992-10-01

59

Uranium industry annual, 1991  

SciTech Connect

In the Uranium Industry Annual 1991, data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2. A feature article entitled The Uranium Industry of the Commonwealth of Independent States'' is included in this report.

Not Available

1992-10-01

60

Cermet Transport, Storage, and Disposal Packages Using Depleted Uranium Dioxide and Steel  

SciTech Connect

It is proposed that the steel components of spent nuclear fuel (SNF) storage casks, transport casks, and repository waste packages (WPs) be replaced with a depleted uranium dioxide (DUO{sub 2})-steel cermet consisting of DUO{sub 2} particulates embedded in a continuous-steel phase. Typical cermets use a sandwich-type construction with clean uncontaminated steel layers on both sides of the cermet. Cermets have several potential advantages over other materials of construction: (1) better gamma and neutron shielding than steel; (2) ability to withstand extreme conditions (fire, accident, sabotage); (3) potential to improve repository performance when used in WPs; and (4) use of excess DUO{sub 2} and recycled steel from nuclear facilities, thereby avoiding disposal costs for these materials. New methods of manufacture and other factors may provide economic incentives for cermet packages when large numbers of casks are manufactured.

Forsberg, C.W.

2001-08-21

61

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

NASA Astrophysics Data System (ADS)

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

Zhao, Yunfeng; Chen, Jing

2008-02-01

62

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

63

Uranium Ore Uranium is extracted  

E-print Network

reaction. Generation of Electricity at Nuclear Power Plants Electricity is generated by nuclear power is concentrated in a solid substance called"yellowcake." Chemical Conversion Plants convert the uranium plants with reactors that use water for moderating nuclear reactions and cooling. Spent Nuclear Fuel Used

64

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

65

Geometallurgy of uranium deposits  

Microsoft Academic Search

Mineralogical controls exert significant control over the extraction of uranium from its ores. Uranium speciation, associated mineralogy, deportment and uranium mineral availability are all factors for consideration when assessing leachability. This study presents data from laboratory uranium extractions undertaken on several contrasting uranium ores from a wide range of orebodies. The results provide insight into the mineralogical factors of importance

R. J. Bowell; J. Grogan; M. Hutton-Ashkenny; C. Brough; K. Penman; D. J. Sapsford

2011-01-01

66

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

67

SEMICONDUCTIVE PROPERTIES OF URANIUM OXIDES  

Microsoft Academic Search

Semiconductors that are based on uranium dioxide (or other actinide compounds) appear possible and could offer significant improvements in performance as compared to conventional Si, Ge, and GaAs materials. The energy band gap (forbidden band gap) for uranium dioxide (UO2) lies between Si and GaAs at the optimum of the band gap vs efficiency curve (1), indicating that one should

Thomas Meek; Michael Hu; M. Jonathan Haire

2001-01-01

68

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

69

URANIUM IN ALKALINE ROCKS  

E-print Network

GENERAL Significant reserves of uranium have been identifieduranium deposit at Kvanefjeld, the Ilimaussaq intrusion, South Greenland, geology, reservesreserves well in excess of ten thousand tons of uranium

Murphy, M.

2011-01-01

70

First principles computational modeling of the surface properties of uranium dioxide  

NASA Astrophysics Data System (ADS)

The interaction of uranium dioxide (UO2) with environmental elements occurs at its exposed surface and a fundamental understanding of this interaction process begins at the atomic scale. In this regard, atomic scale modeling of the properties of clean and adsorbate-covered uranium dioxide (UO2) surfaces can be used to elucidate UO2 surface mechanisms such as corrosion and the formation of complex species via environmental gas adsorption. In this thesis, structural and electronic properties of clean and adsorbatecovered low index UO2 surfaces were modeled using regular and hybrid density functional theory. Specifically, the properties of the clean (111) and (110) surfaces were modeled with hybrid density functional theory. To gain some insight into the surface oxidation of UO2, we performed preliminary modeling studies on the interaction of atomic oxygen with the UO2 (111) surface using density functional theory and hybrid density functional theory. For the clean surface, the evolution of the work function, surface energy, incremental energy, and band gap with respect to the system size was studied. We observed that at five formula units and beyond the surface properties of UO2 converge. The estimated work function, surface energy, and band gap of the (111) surface were 3.5 eV, 0.97 J/m2, and 1.2 eV respectively; the corresponding values for the (110) surface were 2.2 eV, 1.76 J/m2, and 0.65 eV respectively. The localization of the 5f electron states is pronounced at the top surface layer while bulk-like behavior is exhibited at and below the subsurface layer. The Mott-Hubbard type insulating behavior in the bulk is retained in the surfaces, albeit with a smaller band gap. The adsorption of O in the UO2 (111) surface indicates that UO2 oxidation is a stable process. The top site is the preferred adsorption site with adsorption energy of 5.37 eV. The presence of the adsorbate results in the change of the electronic work function by 2.56 eV, implying charge transfer from U to O. The analysis of the electronic density of states indicates hybridization between the O adsorbate 2p electron states and the neighboring U 5f electron states. Furthermore, the presence of the adsorbate did not alter the Mott-Hubbard insulating behavior seen in the bulk crystal and clean surface.

Hoover, Megan

71

Etching of uranium dioxide in nitrogen trifluoride RF plasma glow discharge  

NASA Astrophysics Data System (ADS)

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

Veilleux, John Mark

1999-10-01

72

Issues in uranium availability  

Microsoft Academic Search

The purpose of this publication is to show the process by which information about uranium reserves and resources is developed, evaluated and used. The following three papers in this volume have been abstracted and indexed for the Energy Data Base: (1) uranium reserve and resource assessment; (2) exploration for uranium in the United States; (3) nuclear power, the uranium industry,

J. J. Jr. Schanz; S. S. Adams; R. L. Gordon

1982-01-01

73

Morphologies of uranium and uranium zirconium electrodeposits  

NASA Astrophysics Data System (ADS)

Uranium and uranium-zirconium electrodeposits produced in the Fuel Cycle Facility at Argonne National Laboratory-West were examined using standard metallurgical techniques. Substantial differences in the morphologies of the two types of deposits were observed. Samples from pure uranium deposits were comprised of chains of uranium crystals with a characteristic rhomboidal shape, while the morphologies of samples from deposits containing zirconium in excess of approximately 0.5 wt% showed more polycrystalline features. Zirconium was found to be present as a second, zirconium metal phase at or very near the uranium-zirconium dendrite surfaces. Higher collection efficiencies and total deposit weights were observed for the uranium-zirconium deposits; this performance increase is likely a result of better mechanical properties exhibited by the uranium-zirconium dendrite morphology.

Totemeier, Terry C.; Mariani, Robert D.

1997-12-01

74

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

75

An investigation into the influence of implanted oxygen on krypton behaviour in uranium dioxide during annealing  

NASA Astrophysics Data System (ADS)

It is generally agreed that fission gas release in hyperstoichiometric uranium dioxide is strongly influenced by the excess oxygen. However, the exact mechanisms have not been studied at the fundamental level. The aim of the work reported here was to obtain information on this topic by controlled experiments using an ion implantation approach rather than working with irradiated nuclear fuel. Krypton implants were used to create krypton bubbles in UO 2 samples to which oxygen was then added, again by implantation, to induce local changes in stoichiometry. The effect of the oxygen on subsequent krypton desorption was studied during annealing to high temperatures using transmission electron microscopy and thermal desorption spectroscopy. This combination of techniques on individual samples allowed bubble substructure changes to be followed and directly matched to the gas release measurements. Two clear effects of oxygen were seen. At around 1300 K, a new gas release stage was found; it appeared to be related to the 1600 K peak seen after Kr-only implants and could be attributed to the loss of near-surface krypton gas atom clusters, with accelerated migration in hyperstoichiometric UO 2. However, at higher temperatures the coarsening of bubbles in (Kr + O) regions was surprisingly suppressed with the bubbles appearing more uniform and smaller than in Kr-only areas. It is suggested that excess oxygen might form a complex bubble coating effectively pinning the bubbles to slow bubble migration.

Evans, J. H.; van Veen, A.; Westerduin, K. T.

1994-02-01

76

Vacuum carbothermic reduction of uranium dioxide microspheres in a static graphite bed  

SciTech Connect

Experimental work has been carried out to evaluate the formation of different carbide phases during vacuum carbothermic reduction of UO[sub 2] microspheres in a static bed of graphite powder. Uranium monocarbide has been found to be the only product after 3.6 kilosecond at temperatures up to 2,023 K. In order to find out the reasons for this, present results along with other available information on formation of uranium carbides during carbothermic reduction of UO[sub 2] have been analyzed in detail on the basis of intermediate phase equilibria likely to be present in U-C-O system. It is concluded that uranium monocarbide formation is the result of restricted carbon availability at the surface microspheres.

Mehrotra, R.S. (Bhabha Atomic Research Centre, Bombay (India). Radiometallurgy Div.)

1993-11-01

77

Percutaneous absorption of uranium compounds.  

PubMed

Percutaneous absorption of soluble and insoluble uranium compounds has been induced in order to obtain information on penetration routes and the tissue injury produced by uranium salts. The high electron density of uranium provided a reliable way to visualize, by electron microscopy, the precise localization of the heavy compounds within the tissues. Few minutes after topical application of uranyl nitrate, dense deposits of uranium were observed at the epidermal barrier level. A few hours later, dense deposits were seen filling the intercellular spaces and were also scattered in the cytoplasm and nucleus. Mortality and body weight measurements indicated the high toxicity of uranyl nitrate and ammonium uranyl tricarbonate; uranyl acetate and ammonium diuranate were less toxic. As no penetration was achieved after uranium dioxide, no variations were detected on these parameters. PMID:6832127

de Rey, B M; Lanfranchi, H E; Cabrini, R L

1983-04-01

78

Uranium industry annual 1998  

SciTech Connect

The Uranium Industry Annual 1998 (UIA 1998) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. It contains data for the period 1989 through 2008 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data provides a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Data on uranium raw materials activities for 1989 through 1998, 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 2008, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, and uranium inventories, are shown in Chapter 2. The methodology used in the 1998 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. The Form EIA-858 ``Uranium Industry Annual Survey`` is shown in Appendix D. For the readers convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix E along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 24 figs., 56 tabs.

NONE

1999-04-22

79

ECONOMICS OF UNIRRADIATED PROCESSING PHASES OF URANIUM FUEL CYCLES  

Microsoft Academic Search

Expanding reactor programs prescnt industrial opportunities in their ; fuel processing phases. This . paper considers the manufacture of ; unirradiated uranium fuel materials, including the conversion of uranium ; hexafluoride to uranium metal, uranium dioxide, etc.; their subsequent ; fabrication into fuel elements; and the processing and recycle of accrued scrap. ; The intent is to offer potentinl processors

J. P. Murray; F. S. Patton; R. F. Hibbs; W. L. Griffith

1958-01-01

80

Recovery of uranium alloy  

SciTech Connect

A method is described of recovery of uranium alloy from a mixture of uranium alloy with magnesium fluoride comprising: (a) pretreating uranium fluoride with magnesium at 400/sup 0/-1250/sup 0/C. to form a pretreated mixture of uranium and magnesium fluoride, (b) introducing the pretreated mixture into a molten-salt bath floating on a molten-uranium-alloy trap, (c) allowing the bath to transfer heat to the pretreated mixture to cause the magnesium fluoride to dissolve into the molten-salt bath and the uranium alloy to be molten, (d) allowing molten uranium alloy from the pretreated mixture in the bath to separate from the bath into the trap, (e) discharging separated molten-uranium alloy from the trap, and (f) discharging non-alloy components of the pretreated mixture along with excess molten salt from the bath.

Elliott, G.R.B.

1987-01-13

81

Photodegradation of uranium-citrate complex with uranium recovery  

SciTech Connect

Upon exposure to visible light, uranyl citrate complex showed photodegradation of citric acid to acetic acid and carbon dioxide, with the precipitation of uranium as uranium trioxide (UO[sub 3][center dot]2H[sub 2]O). The initial pH and presence of oxygen affected the rate and extent of photochemical degradation of the complex, the formation of intermediate organic degradation products, and uranium speciation. Under aerobic conditions at pH 3.5, acetic, acetoacetic, 3-oxoglutaric, and malonic acids and acetone were detected; at pH 6.0, 3-oxoglutaric and acetic acids were present. The uranyl U(VI) ion was reduced to uranous U(IV) ion and was subsequently reoxidized to the hexavalent form and precipitated out of solution as uranium trioxide. Uranium trioxide precipitate was insoluble at near-neutral pH and was soluble in acidic pH (<4.1). Under anaerobic conditions, the uranyl citrate complex showed only partial (57%) degradation, and uranium was present in the reduced form as U(IV). Excess citric acid retarded the precipitation of uranium. 26 refs., 9 figs., 1 tab.

Dodge, C.J.; Francis, A.J. (Brookhaven National Lab., Upton, NY (United States))

1994-07-01

82

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

83

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

84

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

NASA Astrophysics Data System (ADS)

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

Amadon, Bernard; Applencourt, Thomas; Bruneval, Fabien

2014-03-01

85

Tetravalent uranium in calcite  

PubMed

X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins. PMID:9703507

Sturchio; Antonio; Soderholm; Sutton; Brannon

1998-08-14

86

Tetravalent uranium in calcite.  

SciTech Connect

X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins.

Sturchio, N. C.; Antonio, M. R.; Soderholm, L.; Sutton, S. R.; Brannon, J. C.; Univ. of Chicago; Washington Univ.

1998-08-14

87

Method for converting uranium oxides to uranium metal  

DOEpatents

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

Duerksen, Walter K. (Norris, TN)

1988-01-01

88

Interaction of uranium amalgam with nitrogen  

Microsoft Academic Search

The authors study the interaction with nitrogen of uranium amalgam with a metal content of 600-1000 mg\\/ml Hg in the temperature range of 350-800 degrees C. They establish that the principle product of the interaction is nonstoichiothermic uranium nitride UN (X = 1.5-1.8). Preliminary washing with dimethylsulfoxide and acetonitrile allows the content of uranium dioxide obtained to be reduced to

K. V. Kuranov; A. G. Maslennikov; V. F. Peretrukhin

1985-01-01

89

Uranium hexafluoride public risk  

SciTech Connect

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

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

1994-08-01

90

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

91

Bioremediation of uranium contamination with enzymatic uranium reduction  

USGS Publications Warehouse

Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and metals evaluated, only high concentrations of copper inhibited uranium reduction. Freeze-dried cells, stored aerobically, reduced uranium as fast as fresh cells. D. desulfuricans reduced uranium in pH 4 and pH 7.4 mine drainage waters and in uraniumcontaining groundwaters from a contaminated Department of Energy site. Enzymatic uranium reduction has several potential advantages over other bioprocessing techniques for uranium removal, the most important of which are as follows: the ability to precipitate uranium that is in the form of a uranyl carbonate complex; high capacity for uranium removal per cell; the formation of a compact, relatively pure, uranium precipitate.

Lovley, D. R.; Phillips, E. J. P.

1992-01-01

92

31 CFR 540.317 - Uranium feed; natural uranium feed.  

... 3 2014-07-01 2014-07-01 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...

2014-07-01

93

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

SciTech Connect

Quantum-mechanical techniques were used to determine the charge distribution of uranium 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 (112) 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, Frances N.; Wang, Jianwei; Ewing, Rodney C.; Becker, U.

2013-03-03

94

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

95

Politics of Uranium  

SciTech Connect

Uranium is the most political of all the elements, the material for the production of both the large amounts of electricity and the most destructive weapons in the world. The problems that its dual potential creates are only now beginning to become evident. Author Norman Moss looks at this situation and sheds light on many of the questions that emerge. The nuclear issue always comes back to how much uranium there is, what can be done with it, and which countries have it. Starting with a concise history of uranium and explaining its technology in terms the nonspecialist can understand, The Politics of Uranium considers the political issues that technical arguments obscure. It tells the little-known story of the international uranium cartel, explains the entanglements of governments with the uranium trade, and describes the consequences of wrong decisions and blunders-especially the problems of nuclear waste. It also examines the intellectual and emotional roots of the anti-nuclear movement.

Moss, N.

1982-01-01

96

Uranium geochemistry, mineralogy, geology, exploration and resources  

Microsoft Academic Search

This book comprises papers on the following topics: history of radioactivity; uranium in mantle processes; transport and deposition of uranium in hydrothermal systems at temperatures up to 300°C: Geological implications; geochemical behaviour of uranium in the supergene environment; uranium exploration techniques; uranium mineralogy; time, crustal evolution and generation of uranium deposits; uranium exploration; geochemistry of uranium in the hydrographic network;

De Vivo

1984-01-01

97

Matrix infrared spectra of the products of uranium-atom reactions with carbon monoxide and carbon dioxide  

SciTech Connect

Uranium atoms from pulsed Nd:YAG laser ablation of a uranium metal target were codeposited with carbon monoxide and carbon dioxide in excess argon at 10K. Infrared spectra following the U + CO reaction revealed strong new absorption bands at 804.4 and 852.6 cm[sup [minus]1], which are assigned to the CUO product on the basis of isotopic shifts, FG matrix calculations, and ab initio pseudopotential calculations. An absorption at 2027.5 cm[sup [minus]1] is attributed to the asymmetric secondary reaction product CU(O)CO. In both the U + Co and U + CO[sub 2] reactions, bands at 870.9 and 1963.8 cm[sup [minus]1] were observed and assigned to the association product of UO[sub 2] and CO. Lastly, in the U + CO[sub 2] experiments, new absorption band pairs were observed at 804.4 and 1799.6 cm[sup [minus]1] and at 801.5 and 2011.7 cm[sup [minus]1]. The former pair was almost destroyed on annealing and is assigned to the OUCO insertion product. The latter pair is attributed to an OCU(O)CO species. The direct reaction of U atoms with CO and CO[sub 2] requires an activation energy, which is provided by hyperthermal U atoms from pulsed laser evaporation. 25 refs., 5 figs., 2 tabs.

Tague, T.J. Jr.; Andrews, L. (Univ. of Virginia, Charlotteville, VA (United States)); Hunt, R.D. (Oak Ridge National Lab., TN (United States))

1993-10-21

98

Preparation of uranium compounds  

DOEpatents

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

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

2013-02-19

99

High-precision molecular dynamics simulation of UO2-PuO2: superionic transition in uranium dioxide  

E-print Network

Our series of articles is devoted to high-precision molecular dynamics simulation of mixed actinide-oxide (MOX) fuel in the rigid ions approximation using high-performance graphics processors (GPU). In this article we assess the 10 most relevant interatomic sets of pair potential (SPP) by reproduction of the Bredig superionic phase transition (anion sublattice premelting) in uranium dioxide. The measurements carried out in a wide temperature range from 300K up to melting point with 1K accuracy allowed reliable detection of this phase transition with each SPP. The {\\lambda}-peaks obtained are smoother and wider than it was assumed previously. In addition, for the first time a pressure dependence of the {\\lambda}-peak characteristics was measured, in a range from -5 GPa to 5 GPa its amplitudes had parabolic plot and temperatures had linear (that is similar to the Clausius-Clapeyron equation for melting temperature).

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

2011-01-01

100

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

101

Uranium metallogenic epochs  

Microsoft Academic Search

The author analyzes the relative distribution of uranium reserves throughout the world in deposits of various origin and age. This serves as a basis for outlining the metallogenic epochs. No data are given on uranium in the Soviet Union, but nevertheless the article appears to be of interest to economic geologists. E. A. Alexandrov.

N. K. Morozenko

1966-01-01

102

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.

103

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

104

Uranium extraction process  

SciTech Connect

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

Rose, M.A.

1983-05-03

105

Uranium: A Dentist's perspective  

PubMed Central

Uranium is a naturally occurring radionuclide found in granite and other mineral deposits. In its natural state, it consists of three isotopes (U-234, U-235 and U-238). On an average, 1% 2% of ingested uranium is absorbed in the gastrointestinal tract in adults. The absorbed uranium rapidly enters the bloodstream and forms a diffusible ionic uranyl hydrogen carbonate complex (UO2HCO3+) which is in equilibrium with a nondiffusible uranyl albumin complex. In the skeleton, the uranyl ion replaces calcium in the hydroxyapatite complex of the bone crystal. Although in North India, there is a risk of radiological toxicity from orally ingested natural uranium, the principal health effects are chemical toxicity. The skeleton and kidney are the primary sites of uranium accumulation. Acute high dose of uranyl nitrate delays tooth eruption, and mandibular growth and development, probably due to its effect on target cells. Based on all previous research and recommendations, the role of a dentist is to educate the masses about the adverse effects of uranium on the overall as well as the dental health. The authors recommended that apart from the discontinuation of the addition of uranium to porcelain, the Public community water supplies must also comply with the Environmental Protection Agency (EPA) standards of uranium levels being not more than 30 ppb (parts per billion). PMID:24478959

Toor, R. S. S.; Brar, G. S.

2012-01-01

106

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

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

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

107

Developments in uranium in 1981  

Microsoft Academic Search

Declining prices and increasing costs continued to influence the uranium industry during 1981. The supply of uranium exceeds the current demand and, as a result, exploration for uranium declined in the United States for the third straight year. During 1981, 107 companies spent $144.8 million on uranium exploration, which included 14.1 million ft of surface drilling. This drilling was mainly

Chenoweth

1982-01-01

108

Developments in uranium in 1982  

Microsoft Academic Search

Slippage in demand, increasing costs, and low spot market prices continued to influence the uranium industry during 1982. The supply of uranium exceeds the current demand and, as a result, exploration for uranium declined in the United States for the fourth straight year. During 1982, 92 companies spent $73.86 million on uranium exploration, including 6.1 million ft of surface drilling.

Chenoweth

1983-01-01

109

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

110

Hot Hydrogen Testing of Tungsten-Uranium Dioxide (W-UO2) CERMET Fuel Materials for Nuclear Thermal Propulsion  

NASA Technical Reports Server (NTRS)

CERMET fuel materials are being developed at the NASA Marshall Space Flight Center for a Nuclear Cryogenic Propulsion Stage. Recent work has resulted in the development and demonstration of a Compact Fuel Element Environmental Test (CFEET) System that is capable of subjecting depleted uranium fuel material samples to hot hydrogen. A critical obstacle to the development of an NCPS engine is the high-cost and safety concerns associated with developmental testing in nuclear environments. The purpose of this testing capability is to enable low-cost screening of candidate materials, fabrication processes, and further validation of concepts. The CERMET samples consist of depleted uranium dioxide (UO2) fuel particles in a tungsten metal matrix, which has been demonstrated on previous programs to provide improved performance and retention of fission products1. Numerous past programs have utilized hot hydrogen furnace testing to develop and evaluate fuel materials. The testing provides a reasonable simulation of temperature and thermal stress effects in a flowing hydrogen environment. Though no information is gained about radiation damage, the furnace testing is extremely valuable for development and verification of fuel element materials and processes. The current work includes testing of subscale W-UO2 slugs to evaluate fuel loss and stability. The materials are then fabricated into samples with seven cooling channels to test a more representative section of a fuel element. Several iterations of testing are being performed to evaluate fuel mass loss impacts from density, microstructure, fuel particle size and shape, chemistry, claddings, particle coatings, and stabilizers. The fuel materials and forms being evaluated on this effort have all been demonstrated to control fuel migration and loss. The objective is to verify performance improvements of the various materials and process options prior to expensive full scale fabrication and testing. Post test analysis will include weight percent fuel loss, microscopy, dimensional tolerance, and fuel stability.

Hickman, Robert; Broadway, Jeramie

2014-01-01

111

India's Worsening Uranium Shortage  

SciTech Connect

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

Curtis, Michael M.

2007-01-15

112

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

113

Recovery of uranium values  

SciTech Connect

A process and apparatus are described for stripping uranium values from a uranium-loaded organic extractant phase containing, usually, a tertiary amine capable of forming organic-soluble uranium complexes. The sulphate-containing aqueous strip liquor is fed in co-current with the extractant phase to be stripped through a number of mixing stages in series connected one to another without intermediate settling stages and finally to a final settling stage. A ''primary'' dispersion is maintained in each mixing stage and controlled stepwise ph adjustment of the mixing stages is effected by metered addition of a base, such as ammonia.

Rowden, G.A.

1980-02-12

114

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

115

Interaction of uranium amalgam with nitrogen  

SciTech Connect

The authors study the interaction with nitrogen of uranium amalgam with a metal content of 600-1000 mg/ml Hg in the temperature range of 350-800 degrees C. They establish that the principle product of the interaction is nonstoichiothermic uranium nitride UN (X = 1.5-1.8). Preliminary washing with dimethylsulfoxide and acetonitrile allows the content of uranium dioxide obtained to be reduced to 3-4 mole %. The authors hypothesize that in the interaction with nitrogen not only metallic uranium dissolved in the mercury takes part, but also thermally unstable intermetallic compounds of the composition UHg /SUB x/ (x = 1-4). An increase in the temperature up to 800 degrees together with a reduction of the partial pressure of the nitrogen to 70 torr does not lead to the formation of stoichiothermic uranium mononitride.

Kuranov, K.V.; Maslennikov, A.G.; Peretrukhin, V.F.

1985-07-01

116

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

117

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

118

Uranium purchases report 1994  

SciTech Connect

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

NONE

1995-07-01

119

Neurotoxicity of depleted uranium  

Microsoft Academic Search

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

George C.-T. Jiang; Michael Aschiner

2006-01-01

120

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

121

Application of Radio-Frequency Plasma Glow Discharge to Removal of Uranium Dioxide from Metal Surfaces  

SciTech Connect

Recent experiments have shown that radio-frequency (rf) plasma glow discharge using NF{sub 3} gas is an effective technique for the removal of uranium oxide from metal surfaces. The results of these experiments are analyzed to explain the measured dependence of the UO{sub 2} removal or etch rate on the NF{sub 3} gas pressure and the absorbed power in the plasma. The NF{sub 3} gas pressure in the experiments was varied from 10.8 to 40 Pa, and the deposited power in the plasma was varied from 25 to 210 W. The UO{sub 2} etch rate was strongly dependent on the absorbed power and, to a lesser extent, on the NF{sub 3} pressure and decreased exponentially with immersion time. At 210 W and 17 Pa, all detectable UO{sub 2} in the samples ({approx}10.6 mg each) was removed at the endpoint, whereas the initial etch rate was {approx}3.11 {mu}m/min. When the absorbed power was {<=}50 W, however, the etch rate was initially {approx}0.5 {mu}g/min and almost zero at the endpoint, with UO{sub 2} only partially etched. This self-limiting etching of UO{sub 2} at low power is attributed to the formation of nonvolatile intermediates UF{sub 2}, UF{sub 3}, UF{sub 4}, UF{sub 5}, UO{sub 2}F, and UO{sub 2}F{sub 2} on the surface. Analysis indicated that the accumulation of UF{sub 6} and, to a lesser extent, O{sub 2} near the surface partially contributed to the exponential decrease in the UO{sub 2} etch rate with immersion time. Unlike fluorination with F{sub 2} gas, etching of UO{sub 2} using rf glow discharge is possible below 663 K. The average etch rates of the amorphous UO{sub 2} in the NF{sub 3} experiments are comparable to the peak values reported in other studies for crystalline UO{sub 2} using CF{sub 4}/O{sub 2} glow discharge performed at {approx}150 to 250 K higher sample temperatures.

El-Genk, Mohamed S.; Saber, Hamed H. [University of New Mexico (United States)

2000-11-15

122

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

123

Evaluation of refractory-metal-clad uranium nitride and uranium dioxide fuel pins after irradiation for times up to 10 450 hours at 990 C  

NASA Technical Reports Server (NTRS)

The effects of some materials variables on the irradiation performance of fuel pins for a lithium-cooled space power reactor design concept were examined. The variables studied were UN fuel density, fuel composition, and cladding alloy. All pins were irradiated at about 990 C in a thermal neutron environment to the design fuel burnup. An 85-percent dense UN fuel gave the best overall results in meeting the operational goals. The T-111 cladding on all specimens was embrittled, possibly by hydrogen in the case of the UN fuel and by uranium and oxygen in the case of the UO2 fuel. Tests with Cb-1Zr cladding indicate potential use of this cladding material. The UO2 fueled specimens met the operational goals of less than 1 percent cladding strain, but other factors make UO2 less attractive than low-density UN for the contemplated space power reactor use.

Bowles, K. J.; Gluyas, R. E.

1975-01-01

124

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

125

Influence of uranium hydride oxidation on uranium metal behaviour  

SciTech Connect

This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

2013-07-01

126

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

127

Mineralogical controls on uranium immobilization at Tono Uranium Deposit, Japan  

Microsoft Academic Search

The Tono uranium deposit, located in central Japan, is thought to have formed when oxidizing groundwater leached uranium from the underlying Toki Granite and transported it to the overlying host sedimentary formations where it precipitated under reducing conditions. Fission-track dating shows that this uranium mineralization took place ~10 million years ago and has remained immobilized despite episodes of sedimentation, uplift,

M. A. Berke; M. A. McKibben; R. C. Arthur; K. Ota; T. Iwatsuki

2002-01-01

128

Method for fabricating uranium foils and uranium alloy foils  

Microsoft Academic Search

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

Gerard L. Hofman; Mitchell K. Meyer; Gaven C. Knighton; Curtis R. Clark

2006-01-01

129

Uranium hexafluoride handling. Proceedings  

SciTech Connect

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

Not Available

1991-12-31

130

The uranium industry of Bulgaria  

Microsoft Academic Search

For 45 years, the Bulgarian uranium industry operated behind an impenetrable veil of secrecy. As this veil is slowly lifted, the breadth and structure of the industry are becoming apparent-and so are the problems. Bulgaria`s uranium industry began in 1945 with the evaluation of several uranium mineral occurrences in the Balkan Mountains. These occurrences provided to be mineable deposits and

Pool

1991-01-01

131

Uranium resources on Federal lands  

Microsoft Academic Search

The scope of this research involves the legal aspects of uranium development, the geological evidence underlying resource estimates, and the engineering aspects of uranium production and nuclear fuel requirements. These topics must all be covered in order to provide a sound basis for economic analysis. Chapter 2 describes the Federal government's role in uranium supply in order to identify the

1979-01-01

132

Uranium resources: Issues and facts  

Microsoft Academic Search

Although there are several secondary issues, the most important uranium resource issue is, ``will there be enough uranium available at a cost which will allow nuclear power to be competitive in the future?`` This paper will attempt to answer this question by discussing uranium supply, demand, and economics from the perspective of the United States. The paper will discuss: how

Delene

1993-01-01

133

URANIUM AND ITS POTENTIAL MARKET  

Microsoft Academic Search

Important developments in recent years and planned future developments ; in the field of nuclear power has clarified the near-term outlook for the uranium ; industry and provided a sound basis for longer range planning. The present ; estimated free-world uranium production is compared with a production chart ; projected to 1971. The United States and Canadian uranium reserves are

Johnson

1963-01-01

134

Australia, uranium and nuclear power  

Microsoft Academic Search

The nuclear debate in Australia is shaped by the nation's substantial base of energy resources, including its large reserves of uranium and recent rises in the market price of uranium. But the debate also echoes Australia's past in the development of programs for nuclear weapons. The proposals include uranium enrichment, the storage of nuclear waste in Australia, and the introduction

Jim Falk; Jim Green; Gavin Mudd

2006-01-01

135

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

136

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

137

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

138

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

139

Depleted Uranium Technical Brief  

E-print Network

Depleted Uranium Technical Brief United States Environmental Protection Agency Office of Air 402-R-06-011 December 2006 Project Officer Brian Littleton U.S. Environmental Protection Agency Office that was prepared by the U.S. Environmental Protection Agency, Office of Radiation and Indoor Air (ORIA

140

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

141

Fluid-bed fluoride volatility process recovers uranium from spent uranium alloy fuels  

NASA Technical Reports Server (NTRS)

Fluid-bed fluoride volatility process recovers uranium from uranium fuels containing either zirconium or aluminum. The uranium is recovered as uranium hexafluoride. The process requires few operations in simple, compact equipment, and eliminates aqueous radioactive wastes.

Barghusen, J. J.; Chilenskas, A. A.; Gunderson, G. E.; Holmes, J. T.; Jonke, A. A.; Kincinas, J. E.; Levitz, N. M.; Potts, G. L.; Ramaswami, D.; Stethers, H.; Turner, K. S.

1967-01-01

142

Method for fabricating uranium foils and uranium alloy foils  

DOEpatents

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

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

2006-09-05

143

Phosphosilicates of tetravalent uranium  

NASA Astrophysics Data System (ADS)

A new variety of P-coffinite of (U,Ca,Fe)[(Si,P,S)O4] idealized formula where P and C are the mineral-forming elements equally to U and Si has been discovered. This allows one to enlarge the list of the known minerals of tetravalent uranium with a new mineral taxon of U4+ phosphosilicates. The crystalline structure of phosphosilicates is difficult to solve because of the dispersity of ?m-sized crystals; therefore, crystallochemical analysis of probable transformations of mineral structures in polyhedrons was carried out. The consideration of the structures from coffinite (U4+-silicate) to ningyoite (Ca-U4+-phosphate) resulted in the conclusion on the possible existence of a series of U4+ minerals of mixed anionic and, hence, cationic composition, i.e., of phosphosilicates and silicophosphates of tetravalent uranium, with the indispensable presence of calcium in the crystalline structure.

Doynikova, O. A.; Sidorenko, G. A.; Sivtsov, A. V.

2014-06-01

144

Uranium in scleractinian coral skeletons  

NASA Astrophysics Data System (ADS)

Accurate determinations have been made of the distribution of uranium in fresh and diagenetically altered coral skeletons occurring both naturally and grown under a variety of experimental conditions. Whereas live coral skeletons are homogeneous in uranium distribution, dead skeletons show heterogeneities relating to lithothamnioid algal encrustations and endolithic sponges. In the analyses of over 100 live coral skeletons, no zonal uranium distributions, described by previous workers, were found. In skeletons, free from organic material, uranium was found to exchange readily with the coral skeleton and/or to be precipitated along trabecular axes and skeletal margins. Bioeroded specimens contained higher uranium concentrations than freshly formed aragonite; they were similar to fossil coral skeletons used by previous researchers for uranium scrics dating.

Swart, P. K.; Hubbard, J. A. E. B.

1982-06-01

145

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

146

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

147

Sputtering of uranium  

NASA Technical Reports Server (NTRS)

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

Gregg, R.; Tombrello, T. A.

1978-01-01

148

Uranium geology of Bulgaria  

SciTech Connect

Three major uranium districts containing several deposits, plus 32 additional deposits, have been identified in Bulgaria, all of which are detailed geologically in this article. Most of the deposits are located in the West Balkan mountains, the western Rhodope mountains, and the Thracian Basin. A few deposits occur in the East Balkan, eastern Rhodope and Sredna Gora mountains. The types of deposits are sandstone, vein, volcanic, and surficial. Sandstone deposits are hosted in Permian and Tertiary sediments. In early 1992, fifteen deposits were being exploited, of which roughly 70 percent of the uranium produced was being recovered using in-situ leaching (ISL) methods. The remainder was being recovered by conventional underground mining, except for one small deposit that utilized open-pit methods. Fifteen other Bulgarian deposits had been exhausted, while five deposits were still in the exploration stage. Uranium production began in Bulgaria in 1946, and cumulative production through 1991 exceeded 100 million pounds equivalent U3O8. Current annual production is on the order of one million pounds equivalent U3O8, about 750 thousand pounds of which are recovered by ISL operations.

Not Available

1993-02-01

149

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

150

Uranium Critical Point Location Problem  

E-print Network

Significant uncertainty of our present knowledge for uranium critical point parameters is under consideration. Present paper is devoted to comparative analysis of possible resolutions for the problem of uranium critical point location, as well as to discussion of plausible scheme of decisive experiment, which could resolve existing uncertainty. New calculations of gas-liquid coexistence in uranium by modern thermodynamic code are included in the analysis.

Iosilevskiy, Igor

2013-01-01

151

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

152

31 CFR 540.309 - Natural uranium.  

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

2014-07-01

153

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. PMID:20195447

Briner, Wayne

2010-01-01

154

Uranium droplet core nuclear rocket  

NASA Technical Reports Server (NTRS)

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

Anghaie, Samim

1991-01-01

155

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

156

Interview regarding Uzbekistan Uranium Reserves  

Microsoft Academic Search

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

Kuchersky

1993-01-01

157

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.

158

URANIUM PYROPHORICITY PHENOMENA AND PREDICTION  

Microsoft Academic Search

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

Martin G. Plys; Michael Epstein; Boro Malinovic

159

HEAT TREATMENT OF ELECTROPLATED URANIUM  

Microsoft Academic Search

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

Hoglund

1958-01-01

160

Method of precipitating uranium peroxide  

SciTech Connect

Uranium peroxide is precipitated from an acidified carbonate strip solution by the addition of hydrogen peroxide and a sufficient quantity of the alkaline carbonate strip solution to maintain the pH at an acid level which is suitable for the precipitation of uranium peroxide.

Hardwicke, T.J.

1984-01-31

161

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

SciTech Connect

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.

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

1993-12-31

162

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

163

Uranium in foraminiferal calcite as a recorder of seawater uranium concentrations  

Microsoft Academic Search

The authors present results of an investigation of uranium\\/calcium ratios in cleaned foraminiferal calcite as a recorder of seawater uranium concentrations. For accurate reconstruction of past seawater uranium content, shell calcite must incorporate uranium in proportion to seawater concentration and must preserve its original uranium composition over time. Laboratory culture experiments with live benthic (Amphistegina lobifera) and live planktonic (Globigerinell

A. D. Russell; S. Emerson; B. K. Nelson; J. Erez; D. W. Lea

1994-01-01

164

Variations in the uranium isotopic compositions of uranium ores from different types of uranium deposits  

NASA Astrophysics Data System (ADS)

Variations in 238U/235U and 234U/238U ratios were measured in uranium minerals from a spectrum of uranium deposit types, as well as diagenetic phosphates in uranium-rich basins and peraluminous rhyolites and associated autunite mineralisation from Macusani Meseta, Peru. Mean ?238U values of uranium minerals relative to NBL CRM 112-A are 0.02 for metasomatic deposits, 0.16 for intrusive, 0.18 for calcrete, 0.18 for volcanic, 0.29 for quartz-pebble conglomerate, 0.29 for sandstone-hosted, 0.44 for unconformity-type, and 0.56 for vein, with a total range in ?238U values from -0.30 to 1.52. Uranium mineralisation associated with igneous systems, including low-temperature calcretes that are sourced from U-rich minerals in igneous systems, have low ?238U values of ca. 0.1, near those of their igneous sources, whereas uranium minerals in basin-hosted deposits have higher and more variable values. High-grade unconformity-related deposits have ?238U values around 0.2, whereas lower grade unconformity-type deposits in the Athabasca, Kombolgie and Otish basins have higher ?238U values. The ?234U values for most samples are around 0, in secular equilibrium, but some samples have ?234U values much lower or higher than 0 associated with addition or removal of 234U during the past 2.5 Ma. These ?238U and ?234U values suggest that there are at least two different mechanisms responsible for 238U/235U and 234U/238U variations. The 234U/238U disequilibria ratios indicate recent fluid interaction with the uranium minerals and preferential migration of 234U. Fractionation between 235U and 238U is a result of nuclear-field effects with enrichment of 238U in the reduced insoluble species (mostly UO2) and 235U in oxidised mobile species as uranyl ion, UO22+, and its complexes. Therefore, isotopic fractionation effects should be reflected in 238U/235U ratios in uranium ore minerals formed either by reduction of uranium to UO2 or chemical precipitation in the form of U6+ minerals. The ?238U values of uranium ore minerals from a variety of deposits are controlled by the isotopic signature of the uranium source, the efficiency of uranium reduction in the case of UO2 systems, and the degree to which uranium was previously removed from the fluid, with less influence from temperature of ore formation and later alteration of the ore. Uranium isotopes are potentially superb tracers of redox in natural systems.

Uvarova, Yulia A.; Kyser, T. Kurt; Geagea, Majdi Lahd; Chipley, Don

2014-12-01

165

Probabilistic estimates of US uranium supply  

Microsoft Academic Search

This report develops and presents probabilistic estimates of total US uranium supply. The word supply is used in the broad sense that both uranium quantity and cost are of interest. Cost implies minimum acceptable selling price rather than market price. Specifically, four types of probability distributions are developed: (1) quantity of US uranium; (2) cost of US uranium; (3) quantity

G. F. Piepel; L. W. Long; R. A. McLaren; C. E. Ford

1981-01-01

166

Characteristic features of the mineralogy of uranium  

Microsoft Academic Search

The following characteristic features of the mineralogy of uraniun are discussed in the article: 1) all known uranium and uranium-bearing minerals contain oxygen; 2) uranium in minerals is present only in the tetra- and hexavalent states; 3) the bulk of the uranium in the earth's crust is concentrated in nonuranium minerals in the form of isomorphous replacement of other elements

V. I. Gerasimovskii

1960-01-01

167

Dynamic Properties of Shock Loaded Uranium Foils  

Microsoft Academic Search

A series of spall experiments have been completed with thin depleted uranium targets. The samples were nominally 0.1 mm thick. The first set of uranium spall targets were rolled to final thickness from low purity uranium. Samples for the second set were cut and ground to their final thickness from high purity (electro-refined) cast uranium. The impactors for these experiments

David Robbins; David Alexander; Robert Hanrahan; Ann Kelly; Ronny Snow; David Stahl; Stephen Sheffield; Russell Gehr; Ted Rupp

2001-01-01

168

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

169

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 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...

2011-07-01

170

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

171

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

172

31 CFR 540.309 - Natural uranium.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 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...

2012-07-01

173

Reaction Kinetics of Powdered Uranium and Deuteroammonia  

Microsoft Academic Search

A rate law for the nitridation of pyrophoric uranium with deuteroammonia was established for the entire course of the reaction. The rate of reaction between powdered uranium and deuteroammonia was determined to be a linear function of the initial Brunauer, Emmett, and Teller (BET) surface area and the fraction of unreacted uranium. Sintering of powdered uranium to a stable surface

R. M. Alire; J. H. McCrary

1966-01-01

174

The End of Cheap Uranium  

E-print Network

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 10+- 2 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 58 +- 4 ktons around the year 2015 is obtained. Thereafter we predict that uranium mine production will decline to at most 54 +- 5 ktons by 2025 and, with the decline steepening, to at most 41 +- 5 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.

Michael Dittmar

2011-06-18

175

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

176

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

177

Uranium bioassay--beyond urinalysis.  

PubMed

Assessment of occupational or environmental exposure to uranium compounds is largely based on urinalysis. However, urine samples generally reflect either recent exposure (within a few days after an incident) or chronic exposure and, furthermore, diurnal fluctuations in "spot samples" make it difficult to estimate the extent of the internal dose received. Thus, if urine samples are not collected within a relatively short time after accidental exposure or if the samples are not representative due to collection logistics, internal dosimetry calculations based only on urinalysis may be misleading. With the advent of efficient and sensitive methods for determination of uranium in hair and nails, some of these drawbacks may be overcome. It is proposed that with little additional cost, determination of the uranium in hair may yield better insights for internal dosimetry of uranium exposure. PMID:11569642

Karpas, Z

2001-10-01

178

Recovery of uranium from shales  

Microsoft Academic Search

The objective of this project is to develop a practical process for recovering uranium from domestic low-grade shales. Recent samples of these shales from Tennessee have been found to contain from 0.005 to 0.009 per cent of uranium. Preceding topical reports on this project (BMI-JDS-101 and -130) have described the work carried out prior to June 30, 1948.

A. E. Bearse; S. Calvert; C. G. Cichooki; R. F. Devine; R. A. Ewing

1948-01-01

179

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.

180

The Work Function of Uranium  

Microsoft Academic Search

The average work functions of vacuum-deposited uranium films and of uranium foil have been measured by the Kelvin contact potential difference method, under ultra-high vacuum conditions. The reference surface was that of well-aged polycrystalline tungsten. A reproducible value of 3.203 +\\/- 0.013 ev was found for the work function of the vacuum-deposited films. In the case of the foil, the

J. C. Rivire

1962-01-01

181

THE WORK FUNCTION OF URANIUM  

Microsoft Academic Search

The average work functions of vacuum-deposited uranium films and of ; uranium foil were measured by the Kelvin contact-potential-difference method, ; under ultrahigh vacuum conditions. The reference surface was that of well-aged ; polycrystalline tungsten. A reproducible value of 3.203 plus or minus 0.013 ev ; was found for the work function of the vacuum-deposited films. In the case of

Riviere

1962-01-01

182

The Work Function of Uranium  

Microsoft Academic Search

The average work functions of vacuum-deposited uranium films and of uranium foil have been measured by the Kelvin contact potential difference method, under ultra-high vacuum conditions. The reference surface was that of well-aged polycrystalline tungsten. A reproducible value of 3.203 0.013 ev was found for the work function of the vacuum-deposited films. In the case of the foil, the

1962-01-01

183

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

184

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

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{sub 2}) in a DUO{sub 2}-steel cermet or a DUCRETE with DUAGG (DUO{sub 2} aggregate) with selective additives in cement matrix. The preparation of DUO{sub 2} particles and aggregates for shielding could be produced from technologies that are extrapolated from the costly multi-step nuclear fuel pellet technologies. Melting the DUO{sub 2} and allowing it to freeze will produce a product near 100% theoretical density and assure that the product produces no volatile materials upon subsequent heating. Melting is a one step process that provides an opportunity to include additives in the DUO{sub 2} to modify its chemical or nuclear properties. The proposed work is directed to develop cold-wall induction heated melters (ICCM) for this specific application. Experiments on melting DUO{sub 2} were carried out in high frequency ICCM with cold crucible. It was experimentally proved an opportunity to produce molten DUO{sub 2} from mixed oxides (DU{sub 3}O{sub 8}) by reducing melting in ICCM. This will allow using DU{sub 3}O{sub 8} generated in direct conversion of depleted uranium hexafluoride as source material for melted and granulated DUO{sub 2} production. Experiments on the addition of alloying components - gadolinium oxide and others into DUO{sub 2} melt while in crucible to improve neutron and gamma radiation-shielding and operation properties of the final solids were carried out. (authors)

Gotovchikov, Vitaly; Seredenko, V.A.; Shatalov, V.V.; Mironov, B.S.; Kaplenkov, V.N.; Seredenko, A.V.; Saranchin, V.K.; Shulgin, A.S.; Kalmakov, Danila [All-Russian Research Institute of Chemical Technology (ARRICT), Kashirskoe Shosse 33, Moscow 115230 (Russian Federation); Haire, M.J.; Forsberg, C.W. [Oak Ridge National Laboratory - ORNL, 1 Bethel Valley Rd, Oak Ridge, TN 37830 (United States)

2007-07-01

185

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

186

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

187

The interaction of uranium metal with nitrogen oxides: The formation of an oxynitride surface layer  

Microsoft Academic Search

The interaction of nitric oxide, nitrogen dioxide and nitrous oxide with a polycrystalline uranium surface has been investigated at 298K. The surface composition and electronic structure of the developing oxide films were studied using X-ray and ultraviolet photoelectron spectroscopy. Nitrous oxide adsorbs dissociatively leaving only oxygen adsorbed on the uranium surface. Nitric oxide and nitrogen dioxide also adsorb dissociatively but

Albert F. Carley; Paul Nevitt; Paul Roussel

2008-01-01

188

Microbial accumulation of uranium, radium, and cesium  

SciTech Connect

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

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

1981-05-01

189

Atomistic properties of ? uranium.  

PubMed

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

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

2012-02-22

190

THE ECONOMY OF URANIUM MINERALS AND THEIR CONCENTRATES  

Microsoft Academic Search

The discovery of uranium fission and its peaceful applications has led ; to the growing economic importance of uranium concentrates so that at present the ; value of the uranium concentrate produced in the free world is exceeded by only ; five minerals. The uranium reserves and the production of uranium concentrates ; are summarized. The use of uranium concentrates

Francisco Pascual Martinez

1960-01-01

191

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

192

Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China  

E-print Network

in the world. D 2004 Elsevier B.V. All rights reserved. Keywords: Roll-front uranium deposit; SandstoneEvidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern Available online 25 January 2005 Abstract We show evidence that the primary uranium minerals, uraninite

Fayek, Mostafa

193

[Determination of uranium in spinach].  

PubMed

After the severe accident at the Fukushima-1 Nuclear Power Plant in March 2011, radioactive contamination of food has become a matter of serious concern in Japan. There is considerable information about radioactive iodine and cesium, but little is known about uranium contamination. We determined uranium content in spinach by the Japanese official method (Manual on Radiation Measurement of Food in Emergency Situations). In the preliminary study, we confirmed that the use of a microwave digestion system for preparing the test solution of spinach could shorten the testing time and give acceptable results. The manual recommends the use of two elements (Tl and Bi) as internal standards for measurement of uranium by ICP-MS. We found that Tl was more suitable than Bi to quantify trace amounts of uranium in spinach. However, it was necessary to determine Tl or Bi concentrations in the sample before analysis, since some samples of spinach contained significant amounts of these elements. The uranium contents of 9 spinach samples bought in April and May 2011 were less than 10 ?g/kg, which are very low compared to the provisional regulatory limit in Japan. PMID:23676689

Kishi, Eri; Yutani, Aiko; Ozaki, Asako; Shinya, Masanao; Katahira, Kenshi; Ooshima, Tomoko; Shimizu, Mitsuru

2013-01-01

194

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

195

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

196

77 FR 14837 - Bioassay at Uranium Mills  

Federal Register 2010, 2011, 2012, 2013

...program acceptable to the NRC staff for uranium mills and applicable portions of uranium conversion facilities where the possibility of exposure to yellowcake dust exists, including exposure conditions with and without the use of respiratory...

2012-03-13

197

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...

198

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

199

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

200

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

201

31 CFR 540.316 - Uranium enrichment.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

202

31 CFR 540.316 - Uranium enrichment.  

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

2014-07-01

203

Uranium in the Monterey Formation of California  

SciTech Connect

Diagenesis that accompanied burial of the diatomaceous Monterey Formation produced diatomite, porcelanite, and chart containing uranium in amounts ranging from less than 2 to more than 1,850 parts per million. Most of the uranium is associated with organic material.The Monterey Formation is a potential large-volume, low-grade uranium source and is a potential source of secondary uranium for sandstone-type deposits.

Durham, D.L.

1987-01-01

204

Electroformation of uranium hemispherical shells  

SciTech Connect

This effort was directed at developing an electrochemical process for forming uniform and dendrite-free deposits of uranium from molten salts. This process is to be used for the electroformation of free-standing hemispherical shells of uranium for nuclear applications. Electrodeposition of uranium onto a substrate was accomplished with a fused chloride mixture containing 42 wt% UCl{sub 3} and a fused chloride-fluoride mixture containing 4 wt % UF{sub 4}. Under pulsed potential control at 504{degree}C, the chloride-fluoride mixture yielded the widest range of plating conditions for which dendrites could be avoided. Bipolar current pulse plating with both electrolytes gave good results, and successful application of this technique to a large tubular cathode has been demonstrated. 24 refs., 10 figs.

Marshall, S.L.; Redey, L.; Vandegrift, G.F.; Vissers, D.R.

1989-11-01

205

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

206

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

207

Geochemical coupling of uranium and phosphorous in soils overlying an unmined uranium deposit: Coles Hill, Virginia  

Microsoft Academic Search

The mineralogy and geochemistry of soils developed over the unmined Coles Hill uranium deposit (Virginia) were studied to determine how phosphorous influences the speciation of uranium in oxidizing soil\\/saprolite systems typical of the eastern US. Results from this study have implications for both uranium remediation (e.g. in situ stabilization) and uranium resource exploration (e.g. near-surface geochemical sampling). The primary uranium

James L. Jerden; A. K. Sinha

2006-01-01

208

Chemical State of Complex Uranium Oxides  

NASA Astrophysics Data System (ADS)

We report here the first direct observation of U(V) in uranium binary oxides and analyze the gradual conversion of the U oxidation state in the mixed uranium systems. Our finding clarifies previous contradicting results and provides important input for the geological disposal of spent fuel, recycling applications, and chemistry of uranium species.

Kvashnina, K. O.; Butorin, S. M.; Martin, P.; Glatzel, P.

2013-12-01

209

BIOREMEDIATION OF URANIUM CONTAMINATED SOILS AND WASTES  

Microsoft Academic Search

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

1998-01-01

210

Bioremediation of uranium contaminated soils and wastes  

Microsoft Academic Search

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

1998-01-01

211

Geology of New Mexico uranium deposits  

Microsoft Academic Search

A discussion of the geology of the uranium deposits of New Mexico was presented. Uranium has been found in all four of the physiographic provinces in New Mexico--the Colorado Plateau, the Southern Rocky Mountains, the Basin and Range, and the Great Plains. The vast majority of uranium is mined in the San Juan Basin of the Colorado Plateau in the

Hatchell

1981-01-01

212

Preserving Ultra-Pure Uranium233  

Microsoft Academic Search

Uranium-233 (U) is a synthetic isotope of uranium formed under reactor conditions during neutron capture by natural thorium (Th). At high purities, this synthetic isotope serves as a crucial reference material for accurately quantifying and characterizing uranium-bearing materials assays and isotopic distributions for domestic and international nuclear safeguards. Separated, high purity U is stored in vaults at Oak Ridge National

Alan M Krichinsky; Steven A. Goldberg; Ian D. Hutcheon

2011-01-01

213

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

214

Uranium in the Vermillion Creek core samples  

Microsoft Academic Search

Unusually high uranium contents in the Vermillion Creek core samples have been determined to be in the shales rather than coals. Uranium contents range from approx. 1 to 138 ppm in the shale and 9 to 20 ppm in the coal. Scanning electron microscopy and fission-track investigations show uranium occurring both as discrete minerals and associated with the organic matter.

J. S. Leventhal; R. B. Finkelman

1987-01-01

215

National Uranium Resource Evaluation: Laredo Quadrangle, Texas  

Microsoft Academic Search

The Laredo Quadrangle, Texas, was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for the occurrence of uranium deposits. The areas were delineated in accordance with criteria established by the National Uranium Resource Evaluation program sponsored by the US Department of Energy. Surface studies included investigations of uranium occurrences described in the literature, location

A. J. Cherepon; A. J. Stauber

1982-01-01

216

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

217

Demonstration of jackhammer incorporating depleted uranium  

Microsoft Academic Search

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 used primarily for either nuclear weapons for the military or nuclear fuel for the commercial power industry. Most of the

L E Fischer; R W Hoard; D L Carter; M D Saculla; G V Wilson

2000-01-01

218

Renal Effects of Uranium in Drinking Water  

Microsoft Academic Search

statistically significantly associated with calcium fractional excretion, but not with phosphate or glucose excretion. Uranium exposure was not associated with creatinine clearance or urinary albu- min, 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.

Pivi Kurttio; Anssi Auvinen; Laina Salonen; Heikki Saha; Juha Pekkanen; Ilona Mkelinen; Sari B. Visnen; Ilkka M. Penttil; Hannu Komulainen

2002-01-01

219

Remediation and Recovery of Uranium from Contaminated  

E-print Network

was stably precipitated until reoxidized in the presence of oxygen. When an electrode was placed in uraniumRemediation and Recovery of Uranium from Contaminated Subsurface Environments with Electrodes K E L that Geobacter species can effectively remove uranium from contaminated groundwater by reducing soluble U

Lovley, Derek

220

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

221

Microbiological control in uranium processing  

SciTech Connect

A method is described of improving the recovery of U/sub 3/O/sub 8/ from circulating aqueous leach fluids used to extract uranium from its ores in underground uranium fields. The fields are made up of a series of injection and producing wells. The aqueous fluids are contaminated by suspended and dissolved inorganic iron compounds caused by the presence of anerobic and anerobic bacteria. The method comprises treating such aqueous leach fluids with at least 0.1 ppm of a mixture of 75% of 5-chloro-2-methyl-4-isothiazolin-3-one and 25% 2-methyl-4-isothiazolin-3-one.

Stuebner, T.L.

1987-04-07

222

Magnetic excitations in uranium nitride  

SciTech Connect

The magnetic inelastic scattering from uranium nitride in the antiferromagnetic and paramagnetic phases has been measured by neutron spectroscopy. The magnetic response at low temperatures is found to be spread over a considerable frequency range and to have longitudinal polarization. No sharp transverse spin-wave modes are observed even though uranium nitride orders antiferromagnetically. With the raising of the temperature towards the Neel temperature, a second longitudinal component of inelastic scattering centered on zero frequency grows rapidly and dominates the low-frequency response. However, at frequencies beyond 5--6 THz there is virtually no change in the observed magnetic scattering.

Holden, T.M.; Buyers, W.J.L.; Svensson, E.C.; Lander, G.H.

1984-07-01

223

Uranium(VI) organoimido complexes  

SciTech Connect

Complexes containing multiply bonded alkylidene, alkylidyne, imido, nitrido, and oxo ligands, and selected combinations thereof, are part of the tapestry of tungsten(VI) chemistry. Aside from uranyl complexes, the only reported molecular coordination compounds of U(VI) are UF{sub 6}, UCl{sub 6}, and the binary alkoxides, U(OR){sub 6}. Uranium(VI) compounds containing the other functional groups listed above have never been reported. Here the authors describe the synthesis and structural characterization of the first uranium(VI) systems containing a multiple bond to nitrogen.

Burns, C.J.; Smith, W.H.; Sattelberger, A.P. (Los Alamos National Lab., NM (USA)); Huffman, J.C. (Indiana Univ., Bloomington (USA))

1990-04-11

224

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

225

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

226

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

227

Rapid non-destructive quantitative estimation of urania/thoria in mixed thorium uranium di-oxide pellets by high-resolution gamma-ray spectrometry.  

PubMed

A non-destructive technique using high-resolution gamma-ray spectrometry has been standardised for quantitative estimation of uranium/thorium in mixed (ThO2-UO2) fuel pellets of varying composition. Four gamma energies were selected; two each from the uranium and thorium series and the time of counting has been optimised. This technique can be used for rapid estimation of U/Th percentage in a large number of mixed fuel pellets from a production campaign. PMID:11300408

Shriwastwa, B B; Kumar, A; Raghunath, B; Nair, M R; Abani, M C; Ramachandran, R; Majumdar, S; Ghosh, J K

2001-06-01

228

Electron Backscatter Diffraction (EBSD) Characterization of Uranium and Uranium Alloys  

SciTech Connect

Electron backscatter diffraction (EBSD) was used to examine the microstructures of unalloyed uranium, U-6Nb, U-10Mo, and U-0.75Ti. For unalloyed uranium, we used EBSD to examine the effects of various processes on microstructures including casting, rolling and forming, recrystallization, welding, and quasi-static and shock deformation. For U-6Nb we used EBSD to examine the microstructural evolution during shape memory loading. EBSD was used to study chemical homogenization in U-10Mo, and for U-0.75Ti, we used EBSD to study the microstructure and texture evolution during thermal cycling and deformation. The studied uranium alloys have significant microstructural and chemical differences and each of these alloys presents unique preparation challenges. Each of the alloys is prepared by a sequence of mechanical grinding and polishing followed by electropolishing with subtle differences between the alloys. U-6Nb and U-0.75Ti both have martensitic microstructures and both require special care in order to avoid mechanical polishing artifacts. Unalloyed uranium has a tendency to rapidly oxidize when exposed to air and a two-step electropolish is employed, the first step to remove the damaged surface layer resulting from the mechanical preparation and the second step to passivate the surface. All of the alloying additions provide a level of surface passivation and different one and two step electropolishes are employed to create good EBSD surfaces. Because of its low symmetry crystal structure, uranium exhibits complex deformation behavior including operation of multiple deformation twinning modes. EBSD was used to observe and quantify twinning contributions to deformation and to examine the fracture behavior. Figure 1 shows a cross section of two mating fracture surfaces in cast uranium showing the propensity of deformation twinning and intergranular fracture largely between dissimilarly oriented grains. Deformation of U-6Nb in the shape memory regime occurs by the motion of twin boundaries formed during the martensitic transformation. Deformation actually results in a coarsening of the microstructure making EBSD more practical following a limited amount of strain. Figure 2 shows the microstructure resulting from 6% compression. Casting of U-10Mo results in considerable chemical segregation as is apparent in Figure 2a. The segregation subsists through rolling and heat treatment processes as shown in Figure 2b. EBSD was used to study the effects of homogenization time and temperature on chemical heterogeneity. It was found that times and temperatures that result in a chemically homogeneous microstructure also result in a significant increase in grain size. U-0.75Ti forms an acicular martinsite as shown in Figure 4. This microstructure prevails through cycling into the higher temperature solid uranium phases.

McCabe, Rodney J. [Los Alamos National Laboratory; Kelly, Ann Marie [Los Alamos National Laboratory; Clarke, Amy J. [Los Alamos National Laboratory; Field, Robert D. [Los Alamos National Laboratory; Wenk, H. R. [University of California, Berkeley

2012-07-25

229

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

230

Uranium 2014 resources, production and demand  

E-print Network

Published every other year, Uranium Resources, Production, and Demand, or the "Red Book" as it is commonly known, is jointly prepared by the OECD Nuclear Energy Agency and the International Atomic Energy Agency. It is the recognised world reference on uranium and is based on official information received from 43 countries. It presents the results of a thorough review of world uranium supplies and demand and provides a statistical profile of the world uranium industry in the areas of exploration, resource estimates, production and reactor-related requirements. It provides substantial new information from all major uranium production centres in Africa, Australia, Central Asia, Eastern Europe and North America. Long-term projections of nuclear generating capacity and reactor-related uranium requirements are provided as well as a discussion of long-term uranium supply and demand issues. This edition focuses on recent price and production increases that could signal major changes in the industry.

Organisation for Economic Cooperation and Development. Paris

2014-01-01

231

Uranium 2005 resources, production and demand  

E-print Network

Published every other year, Uranium Resources, Production, and Demand, or the "Red Book" as it is commonly known, is jointly prepared by the OECD Nuclear Energy Agency and the International Atomic Energy Agency. It is the recognised world reference on uranium and is based on official information received from 43 countries. This 21st edition presents the results of a thorough review of world uranium supplies and demand as of 1st January 2005 and provides a statistical profile of the world uranium industry in the areas of exploration, resource estimates, production and reactor-related requirements. It provides substantial new information from all major uranium production centres in Africa, Australia, Central Asia, Eastern Europe and North America. Projections of nuclear generating capacity and reactor-related uranium requirements through 2025 are provided as well as a discussion of long-term uranium supply and demand issues. This edition focuses on recent price and production increases that could signal major c...

Organisation for Economic Cooperation and Development. Paris

2006-01-01

232

Do we have enough uranium  

Microsoft Academic Search

The question of the adequacy and availability of future uranium resources is debated in this article. The author broadens the question by stating that the importance does not lie in terms of whether or not there is enough, but rather in terms of what it implies for decision making today. The question of whether or not to complete the Clinch

Gaskins

1979-01-01

233

Uranium availability for power generation  

Microsoft Academic Search

Utilities are encouraged to participate in the effort to explore and develop adequate supplies of uranium in order to assure a high level of effort and have some control over production rates. Regulatory commissions are likewise encouraged to be receptive to utility initiatives by granting assurances of favorable rate treatment to cover investments. Confusion arises over the difference between forward

S. M. Stoller; J. F. Hogerton

1977-01-01

234

Uranium: where are the reserves  

Microsoft Academic Search

The total non-communist world uranium reserve is about two million tons, but large portions of this are producible at very low rates. The U. S., with only 12 percent of the reserves, accounts for 50 percent of current production, will account for 40 percent of production by 1980, and thereafter will decline rapidly as a producer without major additions to

1976-01-01

235

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

236

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

SciTech Connect

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

Haas, P.A.

1992-02-01

237

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

2011-06-01

238

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

239

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. PMID:11940450

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

2002-01-01

240

Reports on investigations of uranium anomalies. National Uranium Resource Evaluation  

SciTech Connect

During the National Uranium Resource Evaluation (NURE) program, conducted for the US Department of Energy (DOE) by Bendix Field Engineering Corporation (BFEC), radiometric and geochemical surveys and geologic investigations detected anomalies indicative of possible uranium enrichment. Data from the Aerial Radiometric and Magnetic Survey (ARMS) and the Hydrogeochemical and Stream-Sediment Reconnaissance (HSSR), both of which were conducted on a national scale, yielded numerous anomalies that may signal areas favorable for the occurrence of uranium deposits. Results from geologic evaluations of individual 1/sup 0/ x 2/sup 0/ quadrangles for the NURE program also yielded anomalies, which could not be adequately checked during scheduled field work. Included in this volume are individual reports of field investigations for the following six areas which were shown on the basis of ARMS, HSSR, and (or) geologic data to be anomalous: (1) Hylas zone and northern Richmond basin, Virginia; (2) Sischu Creek area, Alaska; (3) Goodman-Dunbar area, Wisconsin; (4) McCaslin syncline, Wisconsin; (5) Mt. Withington Cauldron, Socorro County, New Mexico; (6) Lake Tecopa, Inyo County, California. Field checks were conducted in each case to verify an indicated anomalous condition and to determine the nature of materials causing the anomaly. The ultimate objective of work is to determine whether favorable conditions exist for the occurrence of uranium deposits in areas that either had not been previously evaluated or were evaluated before data from recent surveys were available. Most field checks were of short duration (2 to 5 days). The work was done by various investigators using different procedures, which accounts for variations in format in their reports. All papers have been abstracted and indexed.

Goodknight, C.S.; Burger, J.A. (comps.) [comps.

1982-10-01

241

Global terrestrial uranium supply and its policy implications : a probabilistic projection of future uranium costs  

E-print Network

An accurate outlook on long-term uranium resources is critical in forecasting uranium costresource relationships, and for energy policy planning as regards the development and deployment of nuclear fuel cycle alternatives. ...

Matthews, Isaac A

2010-01-01

242

Removal of uranium by biosorption  

SciTech Connect

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 remediation of uranium-laden surface water or groundwater impoundments (environmental restoration). The technology may be equally useful as an ``end-of-pipe`` treatment of process effluents (waste management). Successful operation of this process will achieve immobilization of the targeted waste and accompanying volume reduction.

Faison, B.D.; Bonner, J.D. [Oak Ridge National Lab., TN (US); Munroe, N.D. [Florida International Univ., Miami, FL (US). Dept. of Mechanical Engineering; Bloomingburg, G.F. [Univ. of Tennessee, Knoxville, TN (US). Dept. of Chemical Engineering

1993-06-01

243

Uranium and plutonium isotopes in the atmosphere  

SciTech Connect

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

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

1983-04-20

244

Uranium 2009 resources, production and demand  

E-print Network

With several countries currently building nuclear power plants and planning the construction of more to meet long-term increases in electricity demand, uranium resources, production and demand remain topics of notable interest. In response to the projected growth in demand for uranium and declining inventories, the uranium industry the first critical link in the fuel supply chain for nuclear reactors is boosting production and developing plans for further increases in the near future. Strong market conditions will, however, be necessary to trigger the investments required to meet projected demand. The "Red Book", jointly prepared by the OECD Nuclear Energy Agency and the International Atomic Energy Agency, is a recognised world reference on uranium. It is based on information compiled in 40 countries, including those that are major producers and consumers of uranium. This 23rd edition provides a comprehensive review of world uranium supply and demand as of 1 January 2009, as well as data on global ur...

Organisation for Economic Cooperation and Development. Paris

2010-01-01

245

High dose uranium ion implantation into silicon  

SciTech Connect

Implantation of uranium ions into silicon to a maximum dose of 6 x 10/sup 16/ atoms/cm/sup 2/, with a maximum concentration of 6 x 10/sup 21/ atoms/cm/sup 3/, has been carried out. This concentration corresponds to 12 at. % of uranium in the silicon host material. The implanted uranium content was measured by Rutherford backscattering and confirmed by a measurement of the alpha-particle activity of the buried uranium layer. The range and straggling of the uranium, and sputtering of the silicon target by uranium, were measured and are compared with theoretical estimates. The implantation was performed at an ion mean energy of 157 keV using a new kind of high current metal ion source.

Brown, I.G.; Galvin, J.E.; Yu, K.M.

1987-05-01

246

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

247

Luminescence of powdered uranium glasses  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

248

The Uranium-Nitrogen System  

Microsoft Academic Search

The purpose of the persent work is to evaluate the heat of formation of uranium sesquinitride, U2N3. The U2N3 phase is known to form a single solid solution with UN2, while the U2N3 compound with minimum N\\/U ratio is in equilibrium mith UN under a given condition of temperature. The heat of formation for the terminal U2N3 has been calculated

Masahiro KATSURA; Tadao SANO

1967-01-01

249

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

250

Determination of uranium in natural waters  

USGS Publications Warehouse

The fluorophotometric determination of uranium was studied to develop a procedure applicable to the routine analysis of waters. Three grams of the high carbonate flux are used in a dilution procedure with spiking. Because of the comparatively high reflectivity of this large disk and the low uranium concentration, a correction for nonquenched light is required. A formula is developed to compensate for the effect, an electrical fusion device is described, and the problem of fixing uranium in waters is discussed.

Thatcher, L.L.; Barker, F.B.

1957-01-01

251

Uranium resources, exploration and production in Australia  

Microsoft Academic Search

The reasonably assured uranium resources of Australia recoverable at less than $US80\\/kg U (uranium reserves) have increased from 6200 MTU in 1967 to 292,000 MTU in 1979. Additional resources at known deposits and in higher cost categories amount to 151,000 MTU. Exploration programs during this period have been very successful in discovering uranium at low average exploration costs. The potential

G. C. Battey; C. J. Hardy

1981-01-01

252

Uranium mill tailings quarterly report, January-March 1982  

SciTech Connect

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

Latkovich, J.M. (comp.)

1982-05-01

253

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

254

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 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...

2012-07-01

255

Geobacter uraniireducens sp. nov., isolated from subsurface sediment undergoing uranium  

E-print Network

Geobacter uraniireducens sp. nov., isolated from subsurface sediment undergoing uranium with acetate oxidation, was isolated from subsurface sediment undergoing uranium bioremediation. The 16S r was to recover an environmentally relevant Geobacter strain from subsurface sediments undergoing in situ uranium

Lovley, Derek

256

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 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...

2011-07-01

257

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

258

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 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...

2010-07-01

259

31 CFR 540.315 - Uranium-235 (U235).  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

260

31 CFR 540.315 - Uranium-235 (U235).  

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

2014-07-01

261

31 CFR 540.308 - Low Enriched Uranium (LEU).  

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

2014-07-01

262

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

263

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

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

2014-07-01

264

31 CFR 540.306 - Highly Enriched Uranium (HEU).  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

265

31 CFR 540.308 - Low Enriched Uranium (LEU).  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

266

Uranium metal reactions with hydrogen and water vapour and the reactivity of the uranium hydride produced  

SciTech Connect

Within the nuclear industry, metallic uranium has been used as a fuel. If this metal is stored in a hydrogen rich environment then the uranium metal can react with the hydrogen to form uranium hydride which can be pyrophoric when exposed to air. The UK National Nuclear Laboratory has been carrying out a programme of research for Sellafield Limited to investigate the conditions required for the formation and persistence of uranium hydride and the reactivity of the material formed. The experimental results presented here have described new results characterising uranium hydride formed from bulk uranium at 50 and 160 C. degrees and measurements of the hydrolysis kinetics of these materials in liquid water. It has been shown that there is an increase in the proportion of alpha-uranium hydride in material formed at lower temperatures and that there is an increase in the rate of reaction with water of uranium hydride formed at lower temperatures. This may at least in part be attributable to a difference in the reaction rate between alpha and beta-uranium hydride. A striking observation is the strong dependence of the hydrolysis reaction rate on the temperature of preparation of the uranium hydride. For example, the reaction rate of uranium hydride prepared at 50 C. degrees was over ten times higher than that prepared at 160 C. degrees at 20% extent of reaction. The decrease in reaction rate with the extent of reaction also depended on the temperature of uranium hydride preparation.

Godfrey, H. [National Nuclear Laboratory, Workington Laboratory, Havelock Road, Derwent Howe, Cumbria, CA14 3YQ (United Kingdom); Broan, C.; Goddard, D.; Hodge, N.; Woodhouse, G. [National Nuclear Laboratory, Preston Laboratory, Springfields, Salwick, Preston, Lancashire, PR4 0XJ (United Kingdom); Diggle, A. [Sellafield Limited, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom); Orr, R. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

2013-07-01

267

Statistical data of the uranium industry  

SciTech Connect

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

none,

1982-01-01

268

Chemistry of uranium in aluminophosphate glasses  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

269

United States Geological Survey uranium and thorium resource assessment and exploration research program, fiscal year 1979  

Microsoft Academic Search

The following program activities are discussed: uranium geochemistry and mineralogy; uranium in sedimentary environments; uranium in igneous and metamorphic environments; geophysical techniques in uranium and thorium exploration; uranium resource assessment; and thorium investigations and resource assessment.

Offield

1978-01-01

270

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

271

Characterization of uranium and uranium-zirconium deposits produced in electrorefining of spent nuclear fuel  

SciTech Connect

This paper describes the metallurgical characterization of deposits produced in molten salt electrorefining of uranium and uranium - 10.% zirconium alloy. The techniques of characterization are described with emphasis on considerations given to the radioactive and pyrophoric nature of the samples. The morphologies observed and their implications for deposit performance are also presented - samples from pure uranium deposits were comprised of chains of uranium crystals with a characteristic rhomboidal shape, while morphologies of samples from deposits containing zirconium showed more polycrystalline features. Zirconium was found to be present as a second, zirconium metal phase at or very near the uranium-zirconium dendrite surfaces. Higher collection efficiencies and total deposit weights were observed for the uranium-zirconium deposits; this performance increase is likely a result of better mechanical properties exhibited by the uranium-zirconium dendrite morphology. 18 refs., 10 figs., 1 tab.

Totemeier, T.C.

1997-09-01

272

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

1983-01-01

273

The nature of contaminant uranium phases at Fernald  

SciTech Connect

Uranium-contaminated soils at the Fernald Site in Ohio have been examined using transmission electron microscopy. The uranium-bearing phases were identified as calcium uranyl phosphate (meta-autunite), uranium oxide (uraninite), uranium metaphosphate [U(PO{sub 3}){sub 4}], uranium calcium oxide, uranium silicate (boltwoodite), and uranium silicide. Uranium have been deposited on the soil through chemical spills and from the operation of an incinerator plant at the site. The uranium metaphosphate phase was found predominantly at an incinerator site at Fernald. Carbonate leaching in an oxygen environment has removed some of the U(IV) phases, however [U(PO{sub 3}){sub 4}] has not been removed by any of the chemical remediation technologies. The identified phases have been included in geochemical modeling of the uranium, these studies show that meta-autunite is the solubility controlling phase for uranium in Fernald soils.

Buck, E.C.; Dietz, N.L. [Argonne National Lab., IL (United States); Abitz, R.J. [IT Corporation, Albuquerque, NM (United States)

1995-12-31

274

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...

275

Technical Basis for Assessing Uranium Bioremediation Performance  

Microsoft Academic Search

In situ bioremediation of uranium holds significant promise for effective stabilization of U(VI) from groundwater at reduced cost compared to conventional pump and treat. This promise is unlikely to be realized unless researchers and practitioners successfully predict and demonstrate the long-term effectiveness of uranium bioremediation protocols. Field research to date has focused on both proof of principle and a mechanistic

PE Long; SB Yabusaki; PD Meyer; CJ Murray; AL NGuessan

2008-01-01

276

Uranium mine ventilaton costs. Information circular\\/1981  

Microsoft Academic Search

This Bureau of Mines report converts published data on the cost of ventilating uranium mines to a common price base and analyzes there data to determine the cost per ton of uranium ore at various levels of radiation exposure control. There appears to be an exponential increase of cost as the radiation level is lowered. The 1967 base costs are

1981-01-01

277

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

278

Seperation of neptunium from irradiated uranium targets  

Microsoft Academic Search

A new chemical method based in two separation steps was developed to isolate235Np from uranium targets irradiated with charged particles. Neptunium and plutonium are separated from uranium and most of the fission products by ion exchange. Then, neptunium is isolated from plutonium and remaining contaminants by extraction chromatography with tributyl phosphate in hydrochloric acid solution. High decontamination was achieved.

L. F. Bellido; V. J. Robinson; H. E. Sims

1993-01-01

279

Uranium dependence and the proliferation problem  

Microsoft Academic Search

A 20-year ''breathing space'' of adequate uranium supplies is felt to warrant delaying breeder technology until the threat of proliferation can be met with adequate internationally controlled stockpiles and marketing. Although a shift to breeder reactors developed as concern grew over the possibility of depleted uranium reserves, U.S. policy has now reversed this trend in favor of nuclear systems with

1977-01-01

280

LASL approach to uranium geochemical reconnaissance  

Microsoft Academic Search

The US ERDA, as part of the NURE program, has initiated a nationwide Hydrogeochemical and Stream Sediment Reconnaissance (HSSR). The aims of the NURE program are to provide data on which to base more accurate estimates of US uranium reserves for long-range planning and to aid in meeting the nation's projected uranium demands into the next century. The HSSR objective

Sharp; R. R. Jr

1977-01-01

281

Estimating U.S. uranium reserves  

NASA Astrophysics Data System (ADS)

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

Smith, L. L.

1998-12-01

282

Estimating U.S. uranium reserves  

Microsoft Academic Search

This article presents information on the Energy Information Administrations (U.S. Department of Energy) annual estimates\\u000a of U.S. uranium reserves. Encompassed is information for year-end 1997s uranium reserves, which were estimated by employing\\u000a numerous resources.

Luther L. Smith

1998-01-01

283

ENERGY FROM URANIUM AND COAL RESERVES  

Microsoft Academic Search

Tables of estimates are presented of domestic and world uranium reserves ; and resources. Tables are also given that show estimated coal reserves ; recoverable at various price levels for the U. S., the Free World, and the entire ; world. Calculations were made of the heat energy available from the estimated ; uranium and coal reserves. The data are

R. D. Nininger; C. I. Gardner; M. F. Searl; D. W. Kuhn

1960-01-01

284

Principal uranium deposits of the world  

Microsoft Academic Search

The geology of the principal world uranium deposits that have identified uranium reserves and production is summarized including type of deposit, host rock and age of host rock, age of mineralization, depositional environment, and mineralogy. The deposits grouped on maps according to age of host rocks - Precambrian, Paleozoic, Mesozoic, and Cenozoic - and further subdivided into types of deposits

1978-01-01

285

Bernabe Montano uranium deposit, Sandoval County  

Microsoft Academic Search

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

R. G. Kozusko; A. E. Saucier

1980-01-01

286

UPTAKE OF URANIUM FROM DRINKING WATER  

EPA Science Inventory

The gastrointestinal absorption (G.I.) of uranium in man from drinking water was determined by measuring urinary and fecal excretion of 234U and 238U in eight subjects. In order to establish their normal backgrounds of uranium intake and excretion, the subjects collected 24 hour ...

287

Simple colorimetric method determines uranium in tissue  

NASA Technical Reports Server (NTRS)

Simple colorimetric micromethod determines concentrations of uranium in tissue. The method involves dry ashing organic extraction, and colorimetric determination of uranyl ferrocyanide. This uranium determination technique could be used in agricultural research, tracer studies, testing of food products, or medical research.

Doran, D.; Frigerio, N. A.

1967-01-01

288

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

289

Dynamic Properties of Shock Loaded Uranium Foils  

NASA Astrophysics Data System (ADS)

A series of spall experiments have been completed with thin depleted uranium targets. The samples were nominally 0.1 mm thick. The first set of uranium spall targets were rolled to final thickness from low purity uranium. Samples for the second set were cut and ground to their final thickness from high purity (electro-refined) cast uranium. The impactors for these experiments were laser-launched 0.05 mm thick copper flyers, which were 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium spall targets, from deformation to complete spall or separation at higher velocities. Dynamic measurements of the uranium targets free surface velocity were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles and spall strengths (estimated from the magnitude of the pull-back signals), are discussed and compared with the micro-structural evidence of spall from the sectioned uranium targets.

Robbins, David; Alexander, David; Hanrahan, Robert; Kelly, Ann; Snow, Ronny; Stahl, David; Sheffield, Stephen; Gehr, Russell; Rupp, Ted

2001-06-01

290

Controlling uranium reactivity March 18, 2008  

E-print Network

uranium research. In reality, uranium presents a wealth of possibilities for funda- mental chemistry. Many channel. The disparity in size of the reactive sites leads to the formation of different products when exerted by the colossal structure surrounding the reactive site caused a nitrogen atom to be inserted

Meyer, Karsten

291

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

292

D Riso-R-429 Automated Uranium  

E-print Network

, NEUTRON- ACTIVATION ANALYZERS, QUANTITATIVE CHEMICAL ANALYSIS, SENSITIVITY. UDC 549.755.35 : 543CM i D Riso-R-429 Automated Uranium Analysis by Delayed-Neutron Counting H. Kunzendorf, L. Løvborg AUTOMATED URANIUM ANALYSIS BY DELAYED-NEUTRON COUNTING H. Kunzendorf, L. Løvborg and E.M. Christiansen

293

Scrap uranium recycling via electron beam melting  

SciTech Connect

A program is underway at the Lawrence Livermore National Laboratory (LLNL) to recycle scrap uranium metal. Currently, much of the material from forging and machining processes is considered radioactive waste and is disposed of by oxidation and encapsulation at significant cost. In the recycling process, uranium and uranium alloys in various forms will be processed by electron beam melting and continuously cast into ingots meeting applicable specifications for virgin material. Existing vacuum processing facilities at LLNL are in compliance with all current federal and state environmental, safety and health regulations for the electron beam melting and vaporization of uranium metal. One of these facilities has been retrofitted with an auxiliary electron beam gun system, water-cooled hearth, crucible and ingot puller to create an electron beam melt furnace. In this furnace, basic process R&D on uranium recycling will be performed with the goal of eventual transfer of this technology to a production facility.

McKoon, R.

1993-11-01

294

Method for fabricating laminated uranium composites  

DOEpatents

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

Chapman, L.R.

1983-08-03

295

New treatment for uranium in wastewater  

SciTech Connect

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

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

1993-01-01

296

Consolidation of the Uranium Production Industry  

SciTech Connect

As uranium prices fell from the record-high levels of the late 1970s, high-cost, unsubsidized producers the world over began to curtail operations or exit the uranium business entirely. Since 1980, the number of companies actively involved in uranium mining or exploration has decreased markedly. As this exodus has taken place, existing reserves and production operations have become consolidated in the hands of a shrinking number of producers. Some of these are large, vertically integrated nuclear fuel companies that adhere to a very long-term view of the uranium market. To that end, they continue to acquire reserves for that period when most analysts agree the uranium market will recover and prices will rebound to higher levels. For consumers, however, this consolidation of production and reserves into fewer hands could have serious implications in future years.

Beyer, C.M.

1993-08-01

297

Premelting transition in uranium dioxide  

Microsoft Academic Search

Thermal analysis of the cooling curves of small samples of UO2xinitially laser heated (in a high-pressure autoclave to inhibit evaporation) on a subsecond time scale to temperatures just below their melting points [Tm(x)]reveals, in the case of nominally stoichiometric UO2.00, a significant, ?-like, heat capacity [Cp(T)] peak near 2670 K; the cooling curves of samples exposed to a reducing environment,

J. P. Hiernaut; G. J. Hyland; C. Ronchi

1993-01-01

298

Premelting transition in uranium dioxide  

SciTech Connect

Thermal analysis of the cooling curves of small samples of UO[sub 2[+-]x] -- initially laser heated (in a high-pressure autoclave to inhibit evaporation) on a sub-second time scale to temperatures just below their melting points [T[sub m](x)] -- reveals, in the case of nominally stoichiometric UO[sub 2.00], a significant, [lambda]-like, heat capacity [C[sub p](T)] peak near 2,670 K; the cooling curves of samples exposed to a reducing environment, on the other hand, exhibit undercooling, characteristic of a first-order phase transition, while under oxidizing conditions it is found that the premelting transition readily disappears. These findings confirm Bredig's original prediction of a premelting transition in this material, in common with that found in other (nonactinide) fluorites near 0.85T[sub m]. A simple model is presented in terms of which the observed behavior can be rationalized. The model is based on the hypothesis that the premelting transition is due to Frenkel disordering of the oxygen sublattice-a process which is rendered cooperative by attractive interactions between complementary Frenkel defects (oxygen interstitials and vacancies); these interactions are treated in a [open quotes]mean-field[close quotes] approximation. The quantitative degree of maximum disorder (realized just above the transition) is, on the other hand, controlled by repulsive interactions between like defects -- the inclusion of which, solely through their effect on the configurational entropy, satisfactorily reproduces the values inferred from recent high-temperature neutron diffraction experiments. 20 refs., 16 figs., 3 tabs.

Hiernaut, J.P.; Ronchi, C. (European Inst. for Transuranium Elements, Karlsruhe (Germany)); Hyland, G.J. (Univ. of Warwick, Coventry (United Kingdom))

1993-03-01

299

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

2010-02-01

300

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

SciTech Connect

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

Francis, C. W.

1993-09-01

301

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. PMID:7702118

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

1995-01-01

302

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

303

METHODS FOR REMOVING URANIUM FROM DRINKING WATER (JOURNAL VERSION)  

EPA Science Inventory

The number of water supplies with high uranium levels and the possibility of a national uranium regulation has stimulated greater interest in uranium removal technology. The paper summarizes recent information on the effectiveness of various methods for uranium removal from drink...

304

Organic matter and sandstone-type uranium deposits: a primer  

USGS Publications Warehouse

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

Leventhal, Joel S.

1979-01-01

305

Surficial origin of North American pitchblende and related uranium deposits  

Microsoft Academic Search

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

Langford

1977-01-01

306

Challenges dealing with depleted uranium in Germany - Reuse or disposal  

Microsoft Academic Search

During enrichment large amounts of depleted Uranium are produced. In Germany every year 2.800 tons of depleted uranium are generated. In Germany depleted uranium is not classified as radioactive waste but a resource for further enrichment. Therefore since 1996 depleted Uranium is sent to ROSATOM in Russia. However it still has to be dealt with the second generation of depleted

Kai D

2007-01-01

307

Bioremediation of Uranium Plumes with Nano-scale  

E-print Network

Reservation Land MCL for Uranium = 30 g/L MCL for Alpha particles = 15 pCi/L Arizona Well Water energy.cr.usgs.gov/other/uraniumBioremediation of Uranium Plumes with Nano-scale Zero-valent Iron Angela Athey Advisers: Dr. Reyes Undergraduate Student Fellowship Program April 15, 2011 #12;Main Sources of Uranium Natural · Leaching from

Fay, Noah

308

Typomorphism of uranium minerals and its practical significance  

Microsoft Academic Search

Typomorphism refers to a series of minerals, each of which is typically developed only in a narrow range of temperature and pressure. Because uranium's mineralogy is extremely sensitive to physicochemical changes in the environment, trypmorphism of uranium minerals can be used in the exploration of uranium deposits. In this paper, the authors discuss the typomorphic features of non-uranium oxide minerals,

A. A. Chernikov

1982-01-01

309

Method of fabricating a uranium-bearing foil  

Microsoft Academic Search

Methods of fabricating a uranium-bearing foil are described. The foil may be substantially pure uranium, or may be a uranium alloy such as a uranium-molybdenum alloy. The method typically includes a series of hot rolling operations on a cast plate material to form a thin sheet. These hot rolling operations are typically performed using a process where each pass reduces

Jackie G. Gooch; Amy L. DeMint

2012-01-01

310

DEPLETED AND NATURAL URANIUM: CHEMISTRY AND TOXICOLOGICAL EFFECTS  

Microsoft Academic Search

Depleted uranium (DU) is a by-product from the chemical enrichment of naturally occurring uranium. Natural uranium is comprised of three radioactive isotopes: U, U, and U. This enrichment process reduces the radioactivity of DU to roughly 30% of that of natural uranium. Nonmilitary uses of DU include counterweights in airplanes, shields against radiation in medical radiotherapy units and transport of

Elena S. Craft; Aquel W. Abu-Qare; Meghan M. Flaherty; Melissa C. Garofolo; Heather L. Rincavage; Mohamed B. Abou-Donia

2004-01-01

311

Batch Tests with unirradiated uranium metal fuel program report.  

SciTech Connect

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

Kaminski, M. D.

2002-02-21

312

Uranium mineralization in southern Victoria Land, Antarctica  

SciTech Connect

For the past 10 antarctic field seasons, an airborne gamma-ray spectrometric survey has been conducted over widely separated parts of the continent. Localized accumulations of both primary and secondary uranium minerals have been discovered at several localities scattered along the Transantarctic Mountains from the Scott Glacier to northern Victoria Land. A number of highly significant radiation anomalies have been discovered in the area between the Koettlitz Glacier and the Pyramid Trough. The occurrences consist of pegmatite vein complexes which contain an association of primary uranium and thorium minerals. Of still greater significance is the fact that abundant secondary uranium minerals were found in association with the primary deposits, and they indicate clearly that uranium is geochemically mobile under the conditions imposed by the arid polar climate that now exists in southern Victoria Land. Preliminary results of a uranium analysis performed by neutron activation indicate a concentration of 0.12% uranium in a composite sample from the two veins. Even higher levels of thorium are present. The nature of the primary uranium mineralization is currently under investigation. Preliminary results are discussed.

Dreschhoff, G.A.M.; Zeller, E.J.

1986-01-01

313

Dynamic Response of High Temperature Uranium Phases  

SciTech Connect

Unalloyed uranium and uranium-0.78 wt%Ti alloy were studied in planar impact experiments with initial sample temperature ranging from 27 to 860 degree sign C. The velocity of the free surface of the samples was monitored by VISAR. It was found that the dynamic compressive strength of both the materials undergoes two-fold increase in the narrow temperature interval corresponding to the domain of beta-phase of uranium. The increase is followed by abrupt, factor of 3-4, strength drop when the initial state of the tested material is gamma-uranium. Such strength behavior explains the uranium susceptibility to adiabatic shear banding. The spall strength of both the alloys is characterized by similar temperature variations. The strength mechanism (phonon viscosity) acting in gamma-phase of pure uranium seems inherited from its alpha-structure while the strength of beta-uranium is controlled by high resistance to shearing characteristic for material having the structure of intermetallic sigma-phase.

Zaretsky, E. [Mechanical Engineering Dept., Ben Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel); Herrmann, B.; Shvarts, D. [Nuclear Research Center -- Negev, P.O.Box 9001, Beer-Sheva 84106 (Israel)

2006-07-28

314

Fuel powder production from ductile uranium alloys.  

SciTech Connect

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

Clark, C. R.

1998-10-23

315

CONTINUOUS PROCESSES FOR THE DIRECT REDUCTION OF URANIUM HEXAFLUORIDE TO URANIUM TETRAFLUORIDE OF HIGH PURITY AND DENSITY  

Microsoft Academic Search

Contrary to the published literature, the single-step reduction of ; uranium hexafluoride to uranium tetrafluoride with hydrogen was found to be ; quantitative; ous process, both safe and economical, was developed and adapted ; for large-scale production use. The uranium tetrafluoride product was of high ; density and purity. The basoc hydrogen reduction method is actually ; uncomplicated; uranium hexafluoride

S. H. Smiley; D. C. Brater

1958-01-01

316

Fractional absorption of ingested uranium in humans  

SciTech Connect

This paper provides a review and reanalysis of data relating to gastrointestinal (GI) uptake of uranium in humans. Estimates of GI uptake of uranium in adult humans have been derived from results of three controlled experimental studies involving short-term oral intake of an elevated quantity of uranium in fluids, from a controlled balance study conducted in a metabolic research ward of a hospital, and from a variety of environmental studies in which urinary uranium could be related to total intake or total excretion of this element in the same population. For controlled studies, uptake values range from less than 0.1% to about 6% for individual subjects, with central values for different studies falling in the range 1-2.4%. Environmental studies yield central estimates in the range 0.3-3.2%. Expressed as a percentage of total intake of uranium in food and fluids, average GI uptake of uranium in adult humans appears to be about 1-1.5%. Limited intake and excretion data for environmentally exposed human subjects {>=}5 y of age do not reveal important differences with age in uranium uptake, but more definitive information is needed for children. More information is also needed to determine whether fractional uptake of uranium increases with decreasing levels of intake and whether uptake from drinking water is substantially higher than uptake from food. Data for laboratory animals indicate that fractional uptake of uranium depends strongly on the chemical form ingested and the length of time since the last intake of food.

Leggett, R.W. [Oak Ridge National Lab., TN (United States); Harrison, J.D. [National Radiological Protection Board, Oxon (United Kingdom)

1995-04-01

317

Technical Basis for Assessing Uranium Bioremediation Performance  

SciTech Connect

In situ bioremediation of uranium holds significant promise for effective stabilization of U(VI) from groundwater at reduced cost compared to conventional pump and treat. This promise is unlikely to be realized unless researchers and practitioners successfully predict and demonstrate the long-term effectiveness of uranium bioremediation protocols. Field research to date has focused on both proof of principle and a mechanistic level of understanding. Current practice typically involves an engineering approach using proprietary amendments that focuses mainly on monitoring U(VI) concentration for a limited time period. Given the complexity of uranium biogeochemistry and uranium secondary minerals, and the lack of documented case studies, a systematic monitoring approach using multiple performance indicators is needed. This document provides an overview of uranium bioremediation, summarizes design considerations, and identifies and prioritizes field performance indicators for the application of uranium bioremediation. The performance indicators provided as part of this document are based on current biogeochemical understanding of uranium and will enable practitioners to monitor the performance of their system and make a strong case to clients, regulators, and the public that the future performance of the system can be assured and changes in performance addressed as needed. The performance indicators established by this document and the information gained by using these indicators do add to the cost of uranium bioremediation. However, they are vital to the long-term success of the application of uranium bioremediation and provide a significant assurance that regulatory goals will be met. The document also emphasizes the need for systematic development of key information from bench scale tests and pilot scales tests prior to full-scale implementation.

PE Long; SB Yabusaki; PD Meyer; CJ Murray; AL NGuessan

2008-04-01

318

behavior of uranium dioxide in the dissociating gas system N/sub 2/O/sub 4/. in equilibrium 2NO/sub 2/. in equilibrium 2NO + O/sub 2/  

SciTech Connect

The behavior of uranium dioxide in the dissociating gas system N/sub 2/O/sub 4/ .in equilibrium 2NO/sub 2/ .in equilibrium 2NO + O/sub 2/ has been studied at 25-800 degreesC and 0.1-10.0 MPa. At atmosphericpressure and 25-150 degreesC the final product is nitrosonium trinitratouranate, NO(UO/sub 2/(NO/sub 3/)/sub 3/) (NTN). The effect of UO/sub 2/ dispersity on the formation of this compound was studied, and the mechanism of the process has been considered. NTN is formed via an intermediate pounds-UO/sub 3/ stage. Increase of pressure accelerates the process and broadens the region of NTN formation and stability. Above 150 degreesC the main reaction products are uranium oxides in oxidation states higher than 4. At 150-450 degreesC and atmospheric pressure UO /SUB 2+x/ oxides (x =0.31.0) are formed, while at higher temperatures only U/sub 3/O/sub 8/ forms. Increasing the system pressure shifts the region of existence of the oxides formed toward higher temperatures.

Kobets, L.V.; Dolgov, V.M.; Klavsut', G.N.; Umreiko, D.S.

1986-07-01

319

Uranium fluoride and metallic uranium as target materials for heavy-element experiments at SHIP  

NASA Astrophysics Data System (ADS)

In this contribution we describe the production and application of uranium targets for synthesis of heavy elements. The targets are prepared from uranium fluoride (UF 4) and from metallic uranium with thin carbon foils as backing. Targets of UF 4 were produced by thermal evaporation in a similar way as the frequently applied targets out of Bi, Bi 2O 3, Pb, PbS, SmF 3, and NdF 3, prepared mostly from isotopically enriched material [Birgit Kindler, et al., Nucl. Instr. and Meth. A 561 (2006) 107; Bettina Lommel, et al., Nucl. Instr. and Meth. A 561 (2006) 100]. In order to use more intensive beams and to avoid scattering of the reaction products in the target, metallic uranium is favorable. However, evaporation of metallic uranium is not feasible at a sustainable yield. Therefore, we established magnetron sputtering of metallic uranium. We describe production and properties of these targets. First irradiation tests show promising results.

Kindler, Birgit; Ackermann, Dieter; Hartmann, Willi; Heberger, Fritz Peter; Hofmann, Sigurd; Hbner, Annett; Lommel, Bettina; Mann, Rido; Steiner, Jutta

2008-06-01

320

Statistical data of the uranium industry  

SciTech Connect

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

none,

1983-01-01

321

Thermodynamics of the uranium-zirconium system  

NASA Astrophysics Data System (ADS)

Renewed interest in metallic fuel for nuclear reactors has prompted new studies of the thermodynamics and phase equilibria in binary alloys containing uranium, plutonium, and zirconium so that the ternary phase diagram might be calculated. An analysis of the uranium-zirconium alloy system has been performed. Thermodynamic functions for all existing uranium-zirconium phases have been derived and a phase diagram was calculated. These results are compared with the available thermodynamic data and accepted phase diagrams and general agreement was found. Disagreements generally occurred where experimental data were sparse and when previously drawn phase boundaries were found to be inconsistent with theory.

Leibowitz, L.; Blomquist, R. A.; Pelton, A. D.

1989-09-01

322

Uranium nitride behavior at thermionic temperatures  

NASA Technical Reports Server (NTRS)

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

Phillips, W. M.

1973-01-01

323

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

Microsoft Academic Search

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

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

2004-01-01

324

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

SciTech Connect

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

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

1992-12-31

325

Uranium plutonium oxide fuels. [LMFBR  

SciTech Connect

Uranium plutonium oxide is the principal fuel material for liquid metal fast breeder reactors (LMFBR's) throughout the world. Development of this material has been a reasonably straightforward evolution from the UO/sub 2/ used routinely in the light water reactor (LWR's); but, because of the lower neutron capture cross sections and much lower coolant pressures in the sodium cooled LMFBR's, the fuel is operated to much higher discharge exposures than that of a LWR. A typical LMFBR fuel assembly is shown. Depending on the required power output and the configuration of the reactor, some 70 to 400 such fuel assemblies are clustered to form the core. There is a wide variation in cross section and length of the assemblies where the increasing size reflects a chronological increase in plant size and power output as well as considerations of decreasing the net fuel cycle cost. Design and performance characteristics are described.

Cox, C.M.; Leggett, R.D.; Weber, E.T.

1981-01-01

326

Energy spectrum of sputtered uranium  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

327

Process for recovering uranium and\\/or thorium from a liquid containing uranium and\\/or thorium  

Microsoft Academic Search

A process for recovering uranium and\\/or thorium from a liquid containing uranium and\\/or thorium is disclosed, which comprises capturing the uranium and\\/or thorium in the liquid by an amorphous silica precipitate formed by adding water glass to the liquid, making the captured uranium and\\/or thorium elute from the precipitate by acid-treatment, recovering the eluted uranium and\\/or thorium as an acidic

S. Hasegawa; S. Ishiwata; Y. Kuroda; S. Tanaka; T. Watanabe

1982-01-01

328

Layered metal sulfides capture uranium from seawater.  

PubMed

Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. The current methods for uranium removal from water present limitations, such as narrow pH operating range, limited tolerance to high salt concentrations, or/and high cost. We show here that a layered sulfide ion exchanger K(2)MnSn(2)S(6) (KMS-1) overcomes these limitations and is exceptionally capable in selectively and rapidly sequestering high (ppm) as well as trace (ppb) quantities of UO(2)(2+) under a variety of conditions, including seawater. KMS-1 can efficiently absorb the naturally occurring U traces in seawater samples. The results presented here reveal the exceptional potential of sulfide-based ion-exchangers for remediating of uranium-containing wastes and groundwater and for extracting uranium from the sea. PMID:23009164

Manos, Manolis J; Kanatzidis, Mercouri G

2012-10-01

329

Review of uranium mining and milling industry  

Microsoft Academic Search

This report assesses the current status of the domestic mining and milling industry for the nuclear strategy study. Uranium reserves and exploration are also reviewed. Program options are discussed briefly. (DLC)

Vath

1976-01-01

330

Innovative design of uranium startup fast reactors  

E-print Network

Sodium Fast Reactors are one of the three candidates of GEN-IV fast reactors. Fast reactors play an important role in saving uranium resources and reducing nuclear wastes. Conventional fast reactors rely on transuranic ...

Fei, Tingzhou

2012-01-01

331

Process for reducing beta activity in uranium  

DOEpatents

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

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

1985-04-11

332

Depleted uranium disposition study -- Supplement, Revision 1  

SciTech Connect

The Department of Energy Office of Weapons and Materials Planning has requested a supplemental study to update the recent Depleted Uranium Disposition report. This supplemental study addresses new disposition alternatives and changes in status.

Becker, G.W.

1993-11-01

333

THE NITRATION OF POWDERED URANIUM BY NITROGEN  

Microsoft Academic Search

The nitration of powdered uranium by nitrogen was studied by- ; thermograviimetry- between 300 and 700 deg C. The results obtained show the ; complexity of a powdered soidgas reaction and chiefly the effect of granulometry. ; (trauth);

C. Moreau; J. Philippot

1961-01-01

334

Desorption of uranium from amidoxime fiber adsorbent  

SciTech Connect

An amidoxime fibrous adsorbent is contacted with uranium-enriched seawater (10 ppm); about 10 mg uranium is loaded per 1 g dry fiber. Then the rate and yield of uranium desorption from the fiber are determined with various eluents. Acid solutions are superior to alkali carbonate solutions as eluents. With a 0.1 mol[center dot]L[sup [minus]1] HCl solution, desorption is completed in 2 hours regardless of the presence of uranium in the leaching solution up to 15 ppm ([approx]6 [times] 10[sup [minus]5]mol[center dot]L[sup [minus]1]). Serial operation of the adsorption-desorption cycle four times does not affect desorption efficiency, but the addition of heavy metal ions to the eluent at a level of 1.8 [times] 10[sup [minus]3]mol[center dot]L[sup [minus]1] significantly decreases desorption efficiency. 13 refs., 5 figs., 1 tab.

Goto, Akira; Morooka, Shigeharu; Fukamachi, Masakazu; Kusakabe, Katsuki (Kyushu Univ., Fukuoka (Japan)); Kago, Tokihiro (Towa Univ., Fukuoka (Japan))

1993-10-01

335

Uranium ores and depleted uranium in the environment, with a reference to uranium in the biosphere from the Erzgebirge/Sachsen, Germany.  

PubMed

The Erzgebirge ('Ore Mountains') area in the eastern part of Germany was a major source of uranium for Soviet nuclear programs between 1945 and 1989. During this time, the former German Democratic Republic became the third largest uranium producer in the world. The high abundance of uranium in the geological formations of the Erzgebirge are mirrored in the discovery of uranium by M. Klaproth close to Freiberg City in 1789 and the description of the so-called 'Schneeberg' disease, lung cancer caused in miners by the accumulation of the uranium decay product, radon, in the subsurfaces of shafts. Since 1991, remediation and mitigation of uranium at production facilities, rock piles and mill tailings has taken place. In parallel, efforts were initiated to assess the likely adverse effects of uranium mining to humans. The costs of these activities amount to about 6.5 10(9) Euro. A comparison with concentrations of depleted uranium at certain sites is given. PMID:12500804

Meinrath, A; Schneider, P; Meinrath, G

2003-01-01

336

Uranium exploration and production in Canada  

Microsoft Academic Search

In 1978, Canada's uranium reserves, the measured, indicated, and inferred, at a price of up to $175 a kilogram rose by 5.9% to 537,000 MT. A survey by Canada's Department of Energy, Mines and Resources also covers prognosticated uranium reserves. In this category, Canada had resources of 426,000 MT in 1978, an increase of 10% over the previous year. Development

Ediger

1981-01-01

337

The ultimate disposition of depleted uranium  

SciTech Connect

Depleted uranium (DU) is produced as a by-product of the uranium enrichment process. Over 340,000 MTU of DU in the form of UF{sub 6} have been accumulated at the US government gaseous diffusion plants and the stockpile continues to grow. An overview of issues and objectives associated with the inventory management and the ultimate disposition of this material is presented.

Lemons, T.R. [Uranium Enrichment Organization, Oak Ridge, TN (United States)

1991-12-31

338

Evolution of uranium and thorium minerals  

Microsoft Academic Search

The origins and near-surface distributions of the approximately 250 known uranium and\\/or thorium minerals elucidate principles of mineral evolution. This history can be divided into four phases. The first, from ~4.5 to 3.5 Ga, involved successive concentrations of uranium and thorium from their initial uniform trace distribution into magmatic-related fluids from which the first U4+ and Th4+ minerals, uraninite (UO2),

R. M. Hazen; R. C. Ewing; D. A. Sverjensky

2009-01-01

339

Material property correlations for uranium mononitride  

E-print Network

MATERIAL PROPERTY CORRELATIONS FOR URANIUM MONONITRIDE A Thesis by STEVEN LOWE HAYES Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August... 1989 Major Subject: Nuclear Engineering MATERIAL PROPERTY CORRELATIONS FOR URANIUM MONONITRIDE A Thesis by STEVEN LOWE HAYES Approved as to style and content by: K. L. Peddicord (Chair of Committee) R. R. Hart (Member) C. P. Burger (Member...

Hayes, Steven Lowe

2012-06-07

340

Fabrication of Cerium Oxide and Uranium Oxide Microspheres for Space Nuclear Power Applications  

SciTech Connect

Cerium oxide and uranium oxide microspheres are being produced via an internal gelation sol-gel method to investigate alternative fabrication routes for space nuclear fuels. Depleted uranium and non-radioactive cerium are being utilized as surrogates for plutonium-238 (Pu-238) used in radioisotope thermoelectric generators and for enriched uranium required by nuclear thermal rockets. While current methods used to produce Pu-238 fuels at Los Alamos National Laboratory (LANL) involve the generation of fine powders that pose a respiratory hazard and have a propensity to contaminate glove boxes, the sol-gel route allows for the generation of oxide microsphere fuels through an aqueous route. The sol-gel method does not generate fine powders and may require fewer processing steps than the LANL method with less operator handling. High-quality cerium dioxide microspheres have been fabricated in the desired size range and equipment is being prepared to establish a uranium dioxide microsphere production capability.

Jeffrey A. Katalenich; Michael R. Hartman; Robert C. O'Brien

2013-02-01

341

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

SciTech Connect

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

NONE

1995-07-05

342

Uranium Exposures in a Community near a Uranium Processing Facility: Relationship with Hypertension and Hematologic Markers  

PubMed Central

Background Environmental uranium exposure originating as a byproduct of uranium processing can impact human health. The Fernald Feed Materials Production Center functioned as a uranium processing facility from 1951 to 1989, and potential health effects among residents living near this plant were investigated via the Fernald Medical Monitoring Program (FMMP). Methods Data from 8,216 adult FMMP participants were used to test the hypothesis that elevated uranium exposure was associated with indicators of hypertension or changes in hematologic parameters at entry into the program. A cumulative uranium exposure estimate, developed by FMMP investigators, was used to classify exposure. Systolic and diastolic blood pressure and physician diagnoses were used to assess hypertension; and red blood cells, platelets, and white blood cell differential counts were used to characterize hematology. The relationship between uranium exposure and hypertension or hematologic parameters was evaluated using generalized linear models and quantile regression for continuous outcomes, and logistic regression or ordinal logistic regression for categorical outcomes, after adjustment for potential confounding factors. Results Of 8,216 adult FMMP participants 4,187 (51%) had low cumulative uranium exposure, 1,273 (15%) had moderate exposure, and 2,756 (34%) were in the high (>0.50 Sievert) cumulative lifetime uranium exposure category. Participants with elevated uranium exposure had decreased white blood cell and lymphocyte counts and increased eosinophil counts. Female participants with higher uranium exposures had elevated systolic blood pressure compared to women with lower exposures. However, no exposure-related changes were observed in diastolic blood pressure or hypertension diagnoses among female or male participants. Conclusions Results from this investigation suggest that residents in the vicinity of the Fernald plant with elevated exposure to uranium primarily via inhalation exhibited decreases in white blood cell counts, and small, though statistically significant, gender-specific alterations in systolic blood pressure at entry into the FMMP. PMID:20889151

Wagner, Sara E.; Burch, James B.; Bottai, Matteo; Pinney, Susan M.; Puett, Robin; Porter, Dwayne; Vena, John E.; Hbert, James R.

2010-01-01

343

Accumulation of uranium by immobilized persimmon tannin  

SciTech Connect

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 the adsorbent. The uranium accumulating capacity of this adsorbent is several times greater than that of commercially available chelating resins (2-3 mEq/g). Immobilized persimmon tannin has the most favorable features for uranium recovery; high selective adsorption ability, rapid adsorption rate, and applicability in both column and batch systems. The uranium retained on immobilized persimmon tannin can be quantitatively and easily eluted with a very dilute acid, and the adsorbent can thus be easily recycled in the adsorption-desorption process. Immobilized persimmon tannin also has a high affinity for thorium. 23 refs., 13 figs., 7 tabs.

Sakaguchi, Takashi; Nakajima, Akira (Miyazaki Medical College (Japan))

1994-01-01

344

Microbial transformation of uranium in wastes  

SciTech Connect

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

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

1989-01-01

345

Separation of Uranium from (Th,U)O sub 2 Solid Solutions.  

National Technical Information Service (NTIS)

Uranium is separated from mixed oxides of thorium and uranium by a pyrometallurgical process in which the oxides are mixed with a molten chloride salt containing thorium tetrachloride and thorium metal which reduces the uranium oxide to uranium metal whic...

P. Chiotti, M. C. Jha

1976-01-01

346

Uptake and mobility of uranium in black oaks: implications for biomonitoring depleted uranium-contaminated groundwater  

Microsoft Academic Search

In a preliminary study, the uptake and the mobility of uranium (U) by black oak trees (Quercus velutina) were assessed by measuring the isotopic composition of tree rings in two mature oak trees in a heavy metal contaminated bog in Concord, MA. The bog is adjacent to a nuclear industrial facility that has been processing depleted uranium (DU) since 1959.

Jesse D Edmands; Daniel J Brabander; Drew S Coleman

2001-01-01

347

Correcting for uranium fission in instrumental neutron activation analysis of high-uranium rocks  

Microsoft Academic Search

Failure to correct for fission products of235U is shown to result in significant errors in the measured concentrations of La, Sm, Nd, Ba, Zr, and Mo by Instrumental Neutron Activation Analysis of high uranium rocks. Measured and calculated correction factors are presented as the ratio of the fission product to parts per million by weight of uranium in the rock.

M. D. Glascock; P. I. Nabelek; D. D. Weinrich; R. M. Coveney

1986-01-01

348

Predicting 232U Content in Uranium  

SciTech Connect

The minor isotope 232U may ultimately be used for detection or confirmation of uranium in a variety of applications. The primary advantage of 232 U as an indicator of the presence of enriched uranium is the plentiful and penetrating nature of the radiation emitted by its daughter radionuclide 208Tl. A possible drawback to measuring uranium via 232U is the relatively high uncertainty in 232U abundance both within and between material populations. An important step in assessing this problem is to ascertain what determines the 232U concentration within any particular sample of uranium. To this end, we here analyze the production and eventual enrichment of 232 U during fuel-cycle operations. The goal of this analysis is to allow approximate prediction of 232 U quantities, or at least some interpretation of the results of 232U measurements. We have found that 232U is produced via a number of pathways during reactor irradiation of uranium and is subsequently concentrated during the later enrichment of the uranium' s 235U Content. While exact calculations are nearly impossible for both the reactor-production and cascade-enrichment parts of the prediction problem, estimates and physical bounds can be provided as listed below and detailed within the body of the report. Even if precise calculations for the irradiation and enrichment were possible, the ultimate 212U concentration would still depend upon the detailed fuel-cycle history. Assuming that a thennal-diffusion cascade is used to produce highly enriched uranium (HEU), dilution of reactor-processed fuel at the cascade input and the long-term holdup of 232U within the cascade both affect the 232U concentration in the product. Similar issues could be expected to apply for the other isotope-separation technologies that are used in other countries. Results of this analysis are listed below: 0 The 232U concentration depends strongly on the uranium enrichment, with depleted uranium (DU) containing between 1600 and 8000 times less 232U than HEU does. * The 236U/232U concentration ratio in HEU is likely to be between 10{sup 6} and 2 x 10{sup 7}. 0 Plutonium-production reactors yield uranium with between I and 10 ppt of 232u. 0 Much higher 132U concentrations can be obtained in some situations. * Significant variation in the 232U concentration is inevitable. * Cascade enrichment increases the 232U concentration by a factor of at least 200, and possibly as much as 1000. 0 The actual 232U concentration depends upon the dilution at the cascade input.

AJ Peurrung

1999-01-07

349

Transient proteinuria and aminoaciduria in rodents following uranium intoxication  

SciTech Connect

Alternative human bioassay procedures for uranium are being investigated. Aminoaciduria in uranium hexafluoride and uranium mill employees has been examined. Although not conclusive, the results suggest that chronic human urinary uranium concentrations of 30-50 ..mu..g L/sup -1/ produce marked changes in the amino acid excretion profile although no consistent patterns emerged. As part of a program to examine alternative bioassay techniques for occupationally exposed uranium workers and to assist in interpretation of amino acid obtained from human incident exposures, the authors have examined the occurrence of transient aminoaciduria following uranium intoxication in female rats.

Bentley, K.W.; Stockwell, D.R.; Britt, K.A.; Kerr, C.B.

1985-03-01

350

ZDC Effective Cross Section for Run 12 Uranium-Uranium Collisions in RHIC  

E-print Network

An accurate calibration of the luminosity measurement of the 2012 Uranium-Uranium RHIC run at 96 GeV per beam is of the greatest importance in order to measure the total uranium-uranium cross section with a reasonably small error bar. During the run, which lasted from April 20th to May 15th 2012, three vernier scans per experiment were performed. Beam intensities of up to 3.4 10$^{10}$ Uranium ions in one ring were successfully accelerated to flattop at $\\gamma = 103.48$ corresponding to 96 GeV/beam. The desired model $\\beta^*$ value was 0.7 m in the two low beta Interaction Points IP6 and IP8. With these beam parameters interaction rates of up to 15 kHz were achieved. This note presents the data associated with the vernier scans, and discusses the results and systematic effects.

Angelika Drees

2013-12-23

351

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

SciTech Connect

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

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

1982-01-26

352

Microbial Uranium Immobilization Independent of Nitrate Reduction  

SciTech Connect

At many uranium processing and handling facilities, including sites in the U.S. Department of Energy (DOE) complex, high levels of nitrate are present as co-contamination with uranium in groundwater. The daunting prospect of complete nitrate removal prior to the reduction of uranium provides a strong incentive to explore bioremediation strategies that allow for uranium bioreduction and stabilization in the presence of nitrate. Typical in-situ strategies involving the stimulation of metal-reducing bacteria are hindered by low pH environments at this study site and require that the persistent nitrate must first and continuously be removed or transformed prior to uranium being a preferred electron acceptor. This project investigates the possibility of stimulating nitrate-indifferent, pH-tolerant microorganisms to achieve bioreduction of U(VI) despite nitrate persistence. Successful enrichments from U-contaminated sediments demonstrated nearly complete reduction of uranium with very little loss of nitrate from pH 4.9-5.6 using methanol or glycerol as a carbon source. Higher pH enrichments also demonstrated similar U reduction capacity with 5-30% nitrate loss within one week. Bacterial 16S rRNA genes were amplified from uranium-reducing enrichments (pH 5.7-6.7) and sequenced. Phylogenetic analyses classified the clone sequences into four distinct clusters. Data from sequencing and T-RFLP profiles indicated that the majority of the microorganisms stimulated by these enrichment conditions consisted of low G+C Gram-positive bacteria most closely related to Clostridium and Clostridium-like organisms. This research demonstrates that the stimulation of a natural microbial community to immobilize U through bioreduction is possible without the removal of nitrate.

Madden, Andrew [ORNL; Smith, April [Florida State University; Balkwill, Dr. David [Florida State University; Fagan, Lisa Anne [ORNL; Phelps, Tommy Joe [ORNL

2007-01-01

353

Uranium transformations in static microcosms.  

PubMed

Elucidation of complex biogeochemical processes and their effects on speciation of U in the subsurface is critical for developing remediation strategies with an understanding of stability. We have developed static microcosms that are similar to bioreduction process studies in situ under laminar flow conditions or in sediment pores. Uranium L(3)-edge X-ray absorption near-edge spectroscopy analysis with depth in the microcosms indicated that transformation of U(VI) to U(IV) occurred by at least two distinct processes. Extended X-ray absorption fine structure (EXAFS) analysis indicated that initial U(VI) species associated with C- and P-containing ligands were transformed to U(IV) in the form of uraninite and U associated with Fe-bound ligands. Microbial community analysis identified putative Fe(III) and sulfate reducers at two different depths in the microcosms. The slow reduction of U(VI) to U(IV) may contribute the stability of U(IV) within microcosms at 11 months after a decrease in bioreducing conditions due to limited electron donors. PMID:19958005

Kelly, Shelly D; Wu, Wei-Min; Yang, Fan; Criddle, Craig S; Marsh, Terence L; O'Loughlin, Edward J; Ravel, Bruce; Watson, David; Jardine, Philip M; Kemner, Kenneth M

2010-01-01

354

In vitro dissolution of uranium oxide by baboon alveolar macrophages.  

PubMed Central

In vitro cellular dissolution tests for insoluble forms of uranium oxide are technically difficult with conventional methodology using adherent alveolar macrophages. The limited number of cells per flask and the slow dissolution rate in a large volume of nutritive medium are obvious restricting factors. Macrophages in suspension cannot be substituted because they represent different and poorly reproducible functional subtypes with regard to activation and enzyme secretion. Preliminary results on the dissolution of uranium oxide using immobilized alveolar macrophages are promising because large numbers of highly functional macrophages can be cultured in a limited volume. Cells were obtained by bronchoalveolar lavages performed on baboons (Papio papio) and then immobilized after the phagocytosis of uranium octoxide (U3O8) particles in alginate beads linked with Ca2+. The dissolution rate expressed as percentage of initial uranium content in cells was 0.039 +/- 0.016%/day for particles with a count median geometric diameter of 3.84 microns(sigma g = 1.84). A 2-fold increase in the dissolution rate was observed when the same number of particles was immobilized without macrophages. These results, obtained in vitro, suggest that the U3O8 preparation investigated should be assigned to inhalation class Y as recommended by the International Commission on Radiological Protection. Future experiments are intended to clarify this preliminary work and to examine the dissolution characteristics of other particles such as uranium dioxide. It is recommended that the dissolution rate should be measured over an interval of 3 weeks, which is compatible with the survival time of immobilized cells in culture and may reveal transformation states occurring with aging of the particles. PMID:1396447

Poncy, J L; Metivier, H; Dhilly, M; Verry, M; Masse, R

1992-01-01

355

Tags to Track Illicit Uranium and Plutonium  

SciTech Connect

With the expansion of nuclear power, it is essential to avoid nuclear materials from falling into the hands of rogue nations, terrorists, and other opportunists. This paper examines the idea of detection and attribution tags for nuclear materials. For a detection tag, it is proposed to add small amounts [about one part per billion (ppb)] of {sup 232}U to enriched uranium to brighten its radioactive signature. Enriched uranium would then be as detectable as plutonium and thus increase the likelihood of intercepting illicit enriched uranium. The use of rare earth oxide elements is proposed as a new type of 'attribution' tag for uranium and thorium from mills, uranium and plutonium fuels, and other nuclear materials. Rare earth oxides are chosen because they are chemically compatible with the fuel cycle, can survive high-temperature processing operations in fuel fabrication, and can be chosen to have minimal neutronic impact within the nuclear reactor core. The mixture of rare earths and/or rare earth isotopes provides a unique 'bar code' for each tag. If illicit nuclear materials are recovered, the attribution tag can identify the source and lot of nuclear material, and thus help police reduce the possible number of suspects in the diversion of nuclear materials based on who had access. (authors)

Haire, M. Jonathan; Forsberg, Charles W. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831-6166 (United States)

2007-07-01

356

Uranium migration through intact sandstone cores  

NASA Astrophysics Data System (ADS)

Uranium is often considered to be a mobile radioelement in the natural environment owing to its tendency to form stable complexes with a number of aqueous anions, particularly in oxidising milieu. A series of infiltration experiments were devised to investigate this migration behaviour under rigidly controlled laboratory conditions. Intact cores of Permo-Triassic Clashach Sandstone were pre-equilibrated with synthetic groundwater solutions and continuous flow-through of uranium monitored together with pH and concentrations of other ions. Prior to performing each experiment a simulation was carried out using a one-dimensional coupled chemical transport code, encompassing a thermodynamic description of the electrical double layer. These calculations together with electron microscopy indicated the potential role played by iron oxyhydroxide grain coatings in retarding the uranium plume. Thus, a second series of experiments was initiated on pre-acidified cores from which all surface exposed iron had been removed, allowing an assessment of the retention capacity of non-ferric components. Taken together, the data clearly illustrate the strong affinity of aqueous uranium species for natural surfaces even under strongly oxidising conditions. The success of the model in predicting a priori the dominant trends in uranium migration behaviour is encouraging and may aid in prioritising analytical requirements for investigations in more complex geochemical situations than those studied here.

Read, D.; Lawless, T. A.; Sims, R. J.; Butter, K. R.

1993-06-01

357

Demonstration of jackhammer incorporating depleted uranium  

SciTech Connect

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 used primarily for either nuclear weapons for the military or nuclear fuel for the commercial power industry. Most of the depleted uranium remains at the enrichment process plants in the form of depleted uranium hexafluoride (DUF{sub 6}). The Department of Energy (DOE) recently began a study to identify possible commercial applications for the surplus material. One of these potential applications is to use the DU in high-density strikers/hammers in pneumatically driven tools, such as jack hammers and piledrivers to improve their impulse performance. The use of DU could potentially increase tunneling velocity and excavation into target materials with improved efficiency. This report describes the efforts undertaken to analyze the particulars of using DU in two specific striking applications: the jackhammer and chipper tool.

Fischer, L E; Hoard, R W; Carter, D L; Saculla, M D; Wilson, G V

2000-04-01

358

Welding of a powder metallurgy uranium alloy  

SciTech Connect

The interest at the Oak Ridge Y-12 Plant in powder metallurgy (P/M) uranium parts is due to the potential cost savings in the fabrication of the material, to achieving a more homogeneous product, and to the reduction of uranium scrap. The joining of P/M uranium-6 wt-% niobium (U-6Nb) alloys by the electron beam (EB) welding process results in weld porosity. Varying the EB welding parameters did not eliminate the porosity. Reducing the oxygen and nitrogen content in this P/M uranium material did minimize the weld porosity, but this step made the techniques of producing the material more difficult. Therefore, joining wrought and P/M U-6Nb rods with the inertia welding technique is considered. Since no gases will be evolved with the solid-state welding process and the weld area will be compacted, porosity should not be a problem in the inertia welding of uranium alloys. The welds that are evaluated are wrought-to-wrought, wrought-to-P/M, and P/M-to-P/M U-6Nb samples.

Holbert, R.K.; Doughty, M.W.; Alexander-Morrison, G.M. (Fairchild Space Co., Germantown, MD (USA))

1989-05-01

359

Exhausting and regenerating resin for uranium removal  

SciTech Connect

Uranium removal with chloride-form anion exchange resin was studied near Houston, Texas, where an abandoned water supply well contained 120 [mu]g/L uranium and 25 pCi/L radium. With this neutral-pH, sulfate-free water, the resin exhibited enormous capacity for the uranyl tricarbonate complex, still removing 95 percent uranium after nearly 16 months without regeneration and after 302,000 bed volumes of throughput. Computer predictions indicate, however, that the presence of sulfate in feedwater would significantly shorten the run length. The efficiency of uranium removal did not deteriorate at a feed pH as low as 5.6, but when the pH was lowered to 4.3. uranium removal decreased to 50 percent and the run length was shortened to 5,000 bed volumes. Results indicate that sodium chloride (NaCl) was an adequate regenerant and, within the range of 0.5 to 4.0 N, the more concentrated the NaCl, the more efficient it was.

Zhihe Zhang; Clifford, D.A. (Univ. of Houston, TX (United States). Dept. of Environmental Engineering)

1994-04-01

360

Reducing the environmental impact of uranium in-situ recovery.  

SciTech Connect

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

Siegel, Malcolm Dean; Simmons, Ardyth

2010-10-01

361

Prospects for the recovery of uranium from seawater  

E-print Network

A computer program entitled URPE (Uranium Recovery Performance and Economics) has been developed to simulate the engineering performance and provide an economic analysis O of a plant recovering uranium from seawater. The ...

Best, F. R.

1980-01-01

362

RECENT PROGRESS IN THE DESCRIPTIVE MINERALOGY OF URANIUM  

Microsoft Academic Search

The present knowledge of the descriptive mineralogy of uranium and ; thorium is reviewed, and a summary is given in tabular form. The leading ; problems remaining is the descriptive mineralogy of uranium and thorium are ; discussed. (W.D.M.);

C. Frondel

1958-01-01

363

Assessments of long-term uranium supply availability  

E-print Network

The future viability of nuclear power will depend on the long-term availability of uranium. A two-form uranium supply model was used to estimate the date at which peak production will occur. The model assumes a constant ...

Zaterman, Daniel R

2009-01-01

364

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

PubMed Central

This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil. PMID:21998695

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

2011-01-01

365

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

SciTech Connect

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

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

1987-10-01

366

Processes for extraction of uranium and radium from uranium-containing ores using ferric nitrate  

SciTech Connect

A process is described for the extraction of both uranium and radium from uranium ores in the presence of an interfering sulfate ion resulting from the presence of sulfide therein by use of an aqueous ferric nitrate leachant including the steps of: (a) mechanically treating the finely ground ore for the removal of sulfide therefrom; (b) leaching the mechanically treated finely ground ore with aqueous acidic ferric nitrate solution in a concentration from 0.01 to 0.1M for the removal of uranium and radium therefrom to result in a liquid ferric nitrate leachate containing radium and uranium and a wet cake containing radium, uranium and ferric nitrate; (c) treating the ferric nitrate leachate to separate uranium and radium therefrom; (d) separately treating the wet cake for removal of retained ferric nitrate and the residual radium and uranium therefrom; and (e) recirculating a major portion of the ferric nitrate leachate from step (c) for the leaching of more of the mechanically treated finely ground ore.

Nirdosh, I.

1987-03-10

367

Dynamic Properties of Shock Loaded Thin Uranium Foils  

Microsoft Academic Search

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3

David L. Robbins; Ann M. Kelly; David J. Alexander; Robert J. Hanrahan; Ronny C. Snow; Russell J. Gehr; Ted D. Rupp; Stephen A. Sheffield; David B. Stahl

2002-01-01

368

DYNAMIC PROPERTIES OF SHOCK LOADED THIN URANIUM FOILS  

Microsoft Academic Search

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3

D. L. Robbins; A. M. Kelly; D. J. Alexander; R. J. Hanrahan; R. C. Snow; R. J. Gehr; Ted Dean Rupp; S. A. Sheffield; D. B. Stahl

2001-01-01

369

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

SciTech Connect

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

Gray, J.H.

2003-08-28

370

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

PubMed

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

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

2005-07-01

371

Monitoring genotoxic exposure in uranium mines  

SciTech Connect

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

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

1993-10-01

372

TRACE ELEMENT ANALYSES OF URANIUM MATERIALS  

SciTech Connect

The Savannah River National Laboratory (SRNL) has developed an analytical method to measure many trace elements in a variety of uranium materials at the high part-per-billion (ppb) to low part-per-million (ppm) levels using matrix removal and analysis by quadrapole ICP-MS. Over 35 elements were measured in uranium oxides, acetate, ore and metal. Replicate analyses of samples did provide precise results however none of the materials was certified for trace element content thus no measure of the accuracy could be made. The DOE New Brunswick Laboratory (NBL) does provide a Certified Reference Material (CRM) that has provisional values for a series of trace elements. The NBL CRM were purchased and analyzed to determine the accuracy of the method for the analysis of trace elements in uranium oxide. These results are presented and discussed in the following paper.

Beals, D; Charles Shick, C

2008-06-09

373

Depleted uranium hexafluoride: Waste or resource?  

SciTech Connect

the US Department of Energy is evaluating technologies for the storage, disposal, or re-use of depleted uranium hexafluoride (UF{sub 6}). This paper discusses the following options, and provides a technology assessment for each one: (1) conversion to UO{sub 2} for use as mixed oxide duel, (2) conversion to UO{sub 2} to make DUCRETE for a multi-purpose storage container, (3) conversion to depleted uranium metal for use as shielding, (4) conversion to uranium carbide for use as high-temperature gas-cooled reactor (HTGR) fuel. In addition, conversion to U{sub 3}O{sub 8} as an option for long-term storage is discussed.

Schwertz, N.; Zoller, J.; Rosen, R.; Patton, S. [Lawrence Livermore National Lab., CA (United States); Bradley, C. [USDOE Office of Nuclear Energy, Science, Technology, Washington, DC (United States); Murray, A. [SAIC (United States)

1995-07-01

374

Fission enhanced diffusion of uranium in zirconia  

NASA Astrophysics Data System (ADS)

This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin 235UO 2 layer in direct contact with an oxidised zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10 11 ions cm -2 s -1 and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10 -15 cm 2 s -1 at 480 C and compared to uranium thermal diffusion data in ZrO 2 in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data.

Brerd, N.; Chevarier, A.; Moncoffre, N.; Sainsot, Ph.; Faust, H.; Catalette, H.

2005-11-01

375

Fission Enhanced diffusion of uranium in zirconia  

E-print Network

This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin $^{235}UO\\_2$ layer in direct contact with an oxidized zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10$^{11}$ ions cm$^{-2}$ s$^{-1}$ and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10$^{-15}$ cm$^2$ s$^{-1}$ at 480$\\circ$C and compared to uranium thermal diffusion data in ZrO$\\_2$ in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data.

Brerd, N; Moncoffre, N; Sainsot, P; Faust, H; Catalette, H

2005-01-01

376

Depleted uranium plasma reduction system study  

SciTech Connect

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

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

1994-12-01

377

Data feature World natural Uranium production 1992  

SciTech Connect

NUKEM estimates that world uranium production fell more than 13% last year, from 40,729 tonnes U [106 million lbs U308] in 1991 to 35,363 tonnes U [92 million lbs U308] in 1992. Production fell in both the Western World and non-Western World. How much of demand was met by production World uranium production in 1992 amounted to about 65% of reactor consumption. That's assuming that reactor demand of the non-Western World has not changed much from the Uranium Institute's estimate for 1991. Civilian stockpiles are being drawn down on a massive scale while the world waits to see what will become of the military stockpiles that could soon enter the global supply picture.

Not Available

1993-03-01

378

The Uranium industry - yesterday, today, and tomorrow  

SciTech Connect

This article is an edited version of a speech given by Thomas C. Pool, Vice-President of NUEXCO Information Services, at the US Council For Energy Awareness' Uranium Seminar 1993, held October 3-6, 1993, in Tucson, Arizona. In conclusion the author asks where can utilities go for their future needs In short, Canada is, and will be, the world's foremost source of low-cost uranium. Australia could also be a significant low-cost supplier, but not until the political situation with regards to uranium is resolved. Canada probably will be seen as a [open quotes]base load[close quotes] supplier and Australia as a close second. The next tier suppliers are Namibia, South Africa, and the US, all with substantial, moderate-cost production capability currently on standby.

Pool, T.C.

1993-10-01

379

Current status of technology for collection of uranium from seawater  

Microsoft Academic Search

Total amount of uranium resource in seawater is one thousand times of that in terrestrial ores. A polymeric adsorbent being capable of collecting uranium in seawater was developed in early 1980s, since uranium is inevitable resource to operate atomic power plants. This adsorbent fabric was synthesized by radiation-induced graft polymerization which could impart a desired functional group into fibrous trunk

Masao Tamada

380

A Geostatistical Study of the Uranium Deposit at Kvanefjeld,  

E-print Network

this problem appears to be a selective type of kriging. The overall uranium reserves are estimated as approx are identified by the discriminating effect of the individual variable. INIS descriptors; URANIUM ORES? RESERVESRisa-R-468 A Geostatistical Study of the Uranium Deposit at Kvanefjeld, The Ilimaussaq Intrusion

381

Microbial Janitors: Enabling natural microbes to clean up uranium contamination  

E-print Network

to the development of the atomic bomb. Uranium enrichment activities on the Oak Ridge Reservation in the 1940s untilMicrobial Janitors: Enabling natural microbes to clean up uranium contamination Oak Ridge then the uranium and nitrate contamination has spread through the ground and now covers an area of about 7 km

382

Plutonium recovery from spent reactor fuel by uranium displacement  

SciTech Connect

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

Ackerman, J.P.

1991-01-01

383

Molten salt bath heating of uranium and its alloys  

Microsoft Academic Search

In the fabrication of uranium and its alloys, the workpiece is commonly preheated and postheated in a molten salt bath. In this report, past and present uranium salt bath technology is reviewed and critiqued. This critical review points out two distinct fruitful development areas: (1) need for a salt for warm working of uranium and (2) need for a hot

1989-01-01

384

Electrokinetic removal of uranium from contaminated, unsaturated soils  

SciTech Connect

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

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

1997-01-01

385

Uranium and thorium potential of Bayer Process muds. Final report  

Microsoft Academic Search

The study of uranium and thorium potential of Bayer Process mud wastes of the aluminum industry was sponsored by the United States Department of Energy. Eight domestic alumina refineries and one abandoned mud impoundment were visited. Both fresh and impounded mud samples were collected and analyzed for uranium and thorium. Correlation of uranium and thorium values with specific bauxite sources

Baumgardner

1980-01-01

386

Method of separating uranium from iron and thorium  

Microsoft Academic Search

Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with

H. Movaseghi

1986-01-01

387

31 CFR 540.315 - Uranium-235 (U235).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Uranium-235 (U235). 540.315 Section...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions 540.315 Uranium-235 (U235). The term...

2011-07-01

388

31 CFR 540.318 - Uranium Hexafluoride (UF6).  

...2014-07-01 2014-07-01 false Uranium Hexafluoride (UF6). 540.318 Section...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions 540.318 Uranium Hexafluoride (UF6). The term...

2014-07-01

389

10 CFR 39.49 - Uranium sinker bars.  

... 2014-01-01 2014-01-01 false Uranium sinker bars. 39.49 Section 39.49...FOR WELL LOGGING Equipment 39.49 Uranium sinker bars. The licensee may use a uranium sinker bar in well logging applications...

2014-01-01

390

10 CFR 39.49 - Uranium sinker bars.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Uranium sinker bars. 39.49 Section 39.49...FOR WELL LOGGING Equipment 39.49 Uranium sinker bars. The licensee may use a uranium sinker bar in well logging applications...

2013-01-01

391

Recovery of uranium from biological adsorbents?desorption equilibrium  

Microsoft Academic Search

tively low cost. Furthermore, the available uranium up- take equilibrium data have suggested that hydrogen ions can compete very effectively with uranium for the active sites on the microbial biomass and result in reduced over- all uranium uptake by R. arrhi~us.~ A relatively concen- trated acid solution could, therefore, act as an elution agent. Experimental data that have been reported

M. Tsezos

1984-01-01

392

31 CFR 540.315 - Uranium-235 (U235).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Uranium-235 (U235). 540.315 Section...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions 540.315 Uranium-235 (U235). The term...

2013-07-01

393

31 CFR 540.315 - Uranium-235 (U235).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Uranium-235 (U235). 540.315 Section...DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions 540.315 Uranium-235 (U235). The term...

2010-07-01

394

10 CFR 39.49 - Uranium sinker bars.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Uranium sinker bars. 39.49 Section 39.49...FOR WELL LOGGING Equipment 39.49 Uranium sinker bars. The licensee may use a uranium sinker bar in well logging applications...

2011-01-01

395

10 CFR 39.49 - Uranium sinker bars.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Uranium sinker bars. 39.49 Section 39.49...FOR WELL LOGGING Equipment 39.49 Uranium sinker bars. The licensee may use a uranium sinker bar in well logging applications...

2010-01-01

396

10 CFR 39.49 - Uranium sinker bars.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Uranium sinker bars. 39.49 Section 39.49...FOR WELL LOGGING Equipment 39.49 Uranium sinker bars. The licensee may use a uranium sinker bar in well logging applications...

2012-01-01

397

Biokinetic modeling of uranium in man after injection and ingestion  

Microsoft Academic Search

Uranium is a naturally occurring primordial radioactive element. Small amounts found in air, water, and food are regularly consumed and inhaled by humans. Even the military, medical, and industrial use of depleted uranium can affect humans. There is an appreciable retention of incorporated uranium in skeleton, kidneys, and liver, and a review of respective effective dose coefficients has been given

Wei Bo Li; Paul Roth; Wolfgang Wahl; Uwe Oeh; Vera Hllriegl; Herwig G. Paretzke

2005-01-01

398

PHYSICAL METALLURGY AND PROPERTIES OF ZIRCONIUM-URANIUM ALLOYS  

Microsoft Academic Search

The constitution and transformation kinetic behavior of uranium-; zirconium alloys are presented. The system is characterized by complete solid ; solution between gamma uranium and beta zirconium at elevated temperatures and by ; the intermediate hexagonal epsilon phase which forms from this solution at about ; 600 deg C and contains approximately 50 wt.% uranium. Oxygen and nitrogen have a

A. A. Bauer; S. Kass; K. M. Goldman

1958-01-01

399

Appendix IV. Risks Associated with Conventional Uranium Milling Introduction  

E-print Network

), "Final Generic Environmental Impact Statement on Uranium Milling Volume 1 and 2" by U.S. NRC (1980), "Final Environmental Impact Statement for Standards for the Control of Byproduct Materials from Uranium Impact Statement (GEIS) on uranium milling which would provide more detailed information and may include

400

The extraction of uranium by amidoximated orlon.  

PubMed

The nitrile groups in polyacrylonitrile (Orlontrade mark) fabric were converted to amidoxime groups to produce an amidoximated orlon fabric. The amidoximated fabric was evaluated for its ability to extract uranium from aqueous solution with a wide range of temperature and pH values. The conversion of nitrile groups to amidoxime groups was simple and relatively inexpensive. In general, the modified orlon fabric showed superior extractability of uranium at all temperatures and pH values tested when compared to untreated Orlontrade mark fabric. PMID:18967000

Katragadda, S; Gesser, H D; Chow, A

1997-12-19

401

Uranium in NIMROC standard igneous rock samples  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

402

Uranium in the Savannah River Site environment  

SciTech Connect

The purpose of this report is to consolidate the history of environmental uranium studies conducted by SRS and to describe the status of uranium in the environment. The report is intended to be a living document'' that will be updated periodically. This draft issue, February 1992, documents studies that occurred from 1954 to 1989. Data in this report are taken primarily from annual and semiannual environmental reports for SRS. Semiannual reports were published from 1954 through 1962. Annual reports have been published since 1963. Occasionally unpublished data are included in this report for completeness.

Evans, A.G.; Bauer, L.R.; Haselow, J.S.; Hayes, D.W.; Martin, H.L.; McDowell, W.L.; Pickett, J.B.

1992-12-09

403

Ultraslow Wave Nuclear Burning of Uranium-Plutonium Fissile Medium on Epithermal Neutrons  

E-print Network

For a fissile medium, originally consisting of uranium-238, the investigation of fulfillment of the wave burning criterion in a wide range of neutron energies is conducted for the first time, and a possibility of wave nuclear burning not only in the region of fast neutrons, but also for cold, epithermal and resonance ones is discovered for the first time. For the first time the results of the investigation of the Feoktistov criterion fulfillment for a fissile medium, originally consisting of uranium-238 dioxide with enrichments 4.38%, 2.00%, 1.00%, 0.71% and 0.50% with respect to uranium-235, in the region of neutron energies 0.015-10.0eV are presented. These results indicate a possibility of ultraslow wave neutron-nuclear burning mode realization in the uranium-plutonium media, originally (before the wave initiation by external neutron source) having enrichments with respect to uranium-235, corresponding to the subcritical state, in the regions of cold, thermal, epithermal and resonance neutrons. In order to validate the conclusions, based on the slow wave neutron-nuclear burning criterion fulfillment depending on the neutron energy, the numerical modeling of ultraslow wave neutron-nuclear burning of a natural uranium in the epithermal region of neutron energies (0.1-7.0eV) was conducted for the first time. The presented simulated results indicate the realization of the ultraslow wave neutron-nuclear burning of the natural uranium for the epithermal neutrons.

V. D. Rusov; V. A. Tarasov; M. V. Eingorn; S. A. Chernezhenko; A. A. Kakaev; V. M. Vashchenko; M. E. Beglaryan

2014-09-25

404

Materials Compatibility With Uranium Fluorides at High Temperatures. Final report  

SciTech Connect

The objective of an ongoing study being conducted by the Innovative Nuclear Space Power and Propulsion Institute (INSPI) at the University of Florida, is to find suitable materials for use in contact with uranium tetrafluoride from approximately 1200 to 3000 C. This temperature range encompasses both the liquid and gas phase of UF4. In this project ceramic materials were investigated which have been used in the fuel of nuclear reactors. These materials, if compatible with UF4, would be extremely valuable due to their very high melting temperatures, familiar chemistry, and well characterized nuclear properties. Experiments were conducted on thorium dioxide (ThO2) and uranium dioxide (UO2). Samples were exposed to liquid UF4 at 1100 C and to UF4 vaporized at above 1450 C. Exposures took place in a graphite crucible inside an evacuated quartz tube. An inductive heating system was used to heat the crucible and thereby the UF4. Use of the quartz tube allowed direct observation of the ongoing reactions. At the conclusion of each exposure samples of residual gases diluted with nitrogen were run through a gas chromatograph (GC) to determine which gases were released as corrosion products. Subsequent to each experiment remaining samples were weighed then photographed at 2.5x magnification. Powder samples of the surface scales and the bulk samples were then prepared for x-ray diffraction analysis (XRD) to determine composition. Data from the GC and XRD were then correlated with equilibrium reaction product data obtained from F*A*C*T to determine the reactions present. Experiments with uranium dioxide showed that although UO2 does not react significantly with UF4, it does dissolve in liquid UF4 and apparently suffers from ablation when exposed to UF4 vapor.

Anghaie, S.; Hanrahan, R.J. Jr.; Erkmen, Z.E.

1996-04-01

405

Separation and ?-Spectrometric Determination of the Isotopic Compositions of Uranium, Protactinium and Thorium and Their Applications on Dating Uranium Glass  

Microsoft Academic Search

A flow sheet for the isolation of uranium, thorium and protactinium with high radiochemical purity from uranium matrices was developed. The isotopic compositions and the chemical yield of the different metal ions separated were determined by ?-spectroscopy and isotopic dilution, respectively. The developed flow sheet was applied to analyse two uranium matrices, namely: a pitchblende mineral from Atabaska, Canada and

H. F. Aly; M. M. El-Dessouky

1985-01-01

406

Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications  

E-print Network

TRU Transuranics DU Depleted Uranium EBR II Experimental Breeder Reactor II IFR Integral Fast Reactor LVDT Linear Variable Differential Transformer SEM Scanning Electron Microscope BSE Backscatter Electron WDS Wavelength Dispersive....2.1 Isothermal Sintering of Uranium ....................................................... 37 4.2.2 BSE Imaging of Sintered Uranium .................................................... 52 4.2.3 Isothermal Sintering of DU-10Zr...

Helmreich, Grant

2012-02-14

407

Alpha Radiolysis of Sorbed Water on Uranium Oxides and Uranium Oxyfluorides  

SciTech Connect

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

Icenhour, A.S.

2003-09-10

408

Uranium estimation and isotopic disequilibrium study of Siwalik fossil bones  

NASA Astrophysics Data System (ADS)

Solid-state nuclear track detectors have been used for measuring uranium and thorium concentrations in fossil bone samples collected from the Siwalik Himalayas of India. The fission track measurement yields uranium concentration alone, while ?-autoradiography of samples under secular equilibrium yields the total uranium and thorium concentrations. Thus, by combining the results of both measurements, uranium and thorium concentrations are determined. The results of uranium content, as determined by fission track analysis, are distinctly different from those of ?-autoradiography, indicating the existence of radioactive disequilibrium in Siwalik fossil bones.

Bajwa, B. S.; Singh, N. P.; Virk, H. S.

1995-06-01

409

10 CFR 760.1 - Uranium leases on lands controlled by DOE. (Domestic Uranium Program Circular No. 760.1, formerly...  

Code of Federal Regulations, 2010 CFR

...controlled by DOE. (Domestic Uranium Program Circular No. 760.1, formerly (AEC) Domestic Uranium Program Circular 8, 10 CFR 60.8). 760.1 Section 760.1 Energy DEPARTMENT OF ENERGY DOMESTIC URANIUM...

2010-01-01

410

Spectrophotometric determination of uranium in process streams of a uranium extraction plant.  

PubMed

This paper deals with the development and standardization of procedures for the determination of uranium on a routine basis in various process streams of a uranium extraction plant, covering a wide range of concentrations from 350 g 1(-1) down to 5 mg 1(-1) using only a spectrophotometric technique. The self-absorption of uranyl ion in dilute phosphoric acid and the violet-blue colour of the UO(2)(2+)-Arsenazo III complex in 4 M HC1 were exploited for high and low concentrations of uranium, respectively. The methods described were applied to samples of varying nature such as aqueous, organics and solids, involve minimal sample preparation and do not require prior separation of uranium from impurities. The interfering impurities in different process streams were also studied. Large quantities of silica as undissolved material poses a serious interference in the case of UNS and UNF. Considerable quantities of iron in UNS, UNF, UNR and UNRC cause interference. Possible remedies in these cases are suggested. Problems with the direct spectrophotometric measurement of organic samples is discussed. The effect of the presence of large quantities of ammonium nitrate and sodium nitrate in WD samples on the determination of uranium is also discussed. The results are compared with those obtained by volumetry and X-ray fluorescence spectrometry for higher concentrations of uranium and by extraction-spectrophotometry (ethyl acetate-thiocyanate method) for lower concentrations. Relative standard deviation of 1% and 5% for high and low concentrations, respectively, were obtained, which are adequate as far as process stream samples are concerned. The compared results are in fair agreement. The problems associated with the determination of uranium in these process streams are discussed. Experimental results for 10 different process streams normally encountered in a uranium extraction plant are tabulated. PMID:18966745

Murty, B N; Jagannath, Y V; Yadav, R B; Ramamurty, C K; Syamsundar, S

1997-02-01

411

Uranium and other heavy metal resistance and accumulation in bacteria isolated from uranium mine wastes  

Microsoft Academic Search

Ten bacterial strains isolated from uranium mine wastes were characterized in terms of their uranium and other metal resistance and accumulation. 16S rRNA gene sequence analysis identified the strains as members of genera Bacillus, Serratia, and Arthrobacter. Strains were able to utilize various carbon sources, particularly aromatic hydrocarbons, grow at broad pH and temperature ranges and produce non specific acid

Sangeeta Choudhary; Ekramul Islam; Sufia K. Kazy; Pinaki Sar

2012-01-01

412

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

SciTech Connect

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

NONE

1995-07-05

413

Microscopic Characterization of Uranium Nitrides Synthesized by Oxidative Ammonolysis of Uranium Tetrafluoride  

Microsoft Academic Search

The oxidative ammonolysis route was used to synthesize three uranium nitrides, UN2 ,U 2N3, and UN, using UF4 as the starting material. Powder XRD analysis showed the UN2 and U2N3 products to contain less than 1.0 wt % uranium oxides. UO2 level was identified to be 5.0 (0) wt % in the UN product as it is made, but this

G. W. Chinthaka Silva; Charles B. Yeamans; Longzhou Ma; Gary S. Cerefice; Kenneth R. Czerwinski; Alfred P. Sattelberger

2008-01-01

414

Enhanced Uranium Immobilization and Reduction by Geobacter sulfurreducens Biofilms.  

PubMed

Biofilms formed by dissimilatory metal reducers are of interest to develop permeable biobarriers for the immobilization of soluble contaminants such as uranium. Here we show that biofilms of the model uranium-reducing bacterium Geobacter sulfurreducens immobilized substantially more U(VI) than planktonic cells and did so for longer periods of time, reductively precipitating it to a mononuclear U(IV) phase involving carbon ligands. The biofilms also tolerated high and otherwise toxic concentrations (up to 5 mM) of uranium, consistent with a respiratory strategy that also protected the cells from uranium toxicity. The enhanced ability of the biofilms to immobilize uranium correlated only partially with the biofilm biomass and thickness and depended greatly on the area of the biofilm exposed to the soluble contaminant. In contrast, uranium reduction depended on the expression of Geobacter conductive pili and, to a lesser extent, on the presence of the c cytochrome OmcZ in the biofilm matrix. The results support a model in which the electroactive biofilm matrix immobilizes and reduces the uranium in the top stratum. This mechanism prevents the permeation and mineralization of uranium in the cell envelope, thereby preserving essential cellular functions and enhancing the catalytic capacity of Geobacter cells to reduce uranium. Hence, the biofilms provide cells with a physically and chemically protected environment for the sustained immobilization and reduction of uranium that is of interest for the development of improved strategies for the in situ bioremediation of environments impacted by uranium contamination. PMID:25128347

Cologgi, Dena L; Speers, Allison M; Bullard, Blair A; Kelly, Shelly D; Reguera, Gemma

2014-11-01

415

Fungi outcompete bacteria under increased uranium concentration in culture media.  

PubMed

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

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

2013-06-01

416

Extractive Electrospray Ionization Mass Spectrometry for Uranium Chemistry Studies  

PubMed Central

Uranium chemistry is of sustainable interest. Breakthroughs in uranium studies make serious impacts in many fields including chemistry, physics, energy and biology, because uranium plays fundamentally important roles in these fields. Substantial progress in uranium studies normally requires development of novel analytical tools. Extractive electrospray ionization mass spectrometry (EESI-MS) is a sensitive technique for trace detection of various analytes in complex matrices without sample pretreatment. EESI-MS shows excellent performance for monitoring uranium species in various samples at trace levels since it tolerates extremely complex matrices. Therefore, EESI-MS is an alternative choice for studying uranium chemistry, especially when it combines ion trap mass spectrometry. In this presentation, three examples of EESI-MS for uranium chemistry studies will be given, illustrating the potential applications of EESI-MS in synthesis chemistry, physical chemistry, and analytical chemistry of uranium. More specifically, case studies on EESI-MS for synthesis and characterization of novel uranium species, and for rapid detection of uranium and its isotope ratios in various samples will be presented. Novel methods based on EESI-MS for screening uranium ores and radioactive iodine-129 will be presented. PMID:24349940

Chen, Huanwen; Luo, Mingbiao; Xiao, Saijin; Ouyang, Yongzhong; Zhou, Yafei; Zhang, Xinglei

2013-01-01

417

Pyrophoricity of uranium in long-term storage environments  

SciTech Connect

A corrosion cycle for uranium is postulated which can be used to assess whether a given storage situation might produce fire hazards and/or continual uranium corrosion. A significant reaction rate of uranium and moisture occurs at room temperature which produces uranium oxide and hydrogen. If the hydrogen cannot escape, it will react slowly with uranium to form uranium hydride. The hydride is pyrophoric at room temperature when exposed to air. Either the hydrogen or the hydride can produce a dangerous situation as demonstrated by two different incidents described here. Long-term corrosion will occur even if the normal precautions are taken as is demonstrated by the long-term storage of stainless steel clad uranium fuel plates. The major initiator of these problems is attributed to any moisture condensed on the metal or any brought in by the cover gas. The postulated corrosion cycle is used to suggest ways to circumvent these problems.

Solbrig, C W; Krsul, J R; Olsen, D N

1994-01-01

418

Tris(bis(trimethylsilyl)amido)uranium: Compounds with tri-, tetra-, and penta-valent uranium  

SciTech Connect

The trivalent uranium compound, tris(bis(trimethylsilyl)amido)uranium, serves as a precursor to new tri-, tetra-, and penta-valent uranium species. The geometry about the uranium atom in the three-coordinate bis(trimethylsilyl)amide compound is pyramidal. Lewis-base coordination compounds of U(N(SiMe{sub 3}){sub 2}){sub 3} with one-to-one ratio of Lewis base to uranium were isolated with pyridine, 4-dimethylaminopyridine, 2,6-Me{sub 2}-C{sub 6}H{sub 3}NC, and triphenylphosphineoxide. Two-to-one coordination compounds were obtained with t-butylnitrile and t-butylisocyanide. Compounds with more sterically demanding bases could not be isolated, presumably due to the steric requirements of the bulky bis(trimethylsilyl)amide ligands. Various reactions of the tris(bis(trimethylsilyl)amido)uranium with AgF, (C{sub 6}H{sub 5}){sub 3}CN{sub 3}, and organoazides are reported. The preparation of the silox compounds U(silox){sub 3}Cl{sub 2},Li and U(silox){sub 4} is reported.

Stewart, J.L.

1988-01-01

419

Semiconductor neutron detectors using depleted uranium oxide  

NASA Astrophysics Data System (ADS)

This paper reports on recent attempts to develop and test a new type of solid-state neutron detector fabricated from uranium compounds. It has been known for many years that uranium oxide (UO2), triuranium octoxide (U3O8) and other uranium compounds exhibit semiconducting characteristics with a broad range of electrical properties. We seek to exploit these characteristics to make a direct-conversion semiconductor neutron detector. In such a device a neutron interacts with a uranium nucleus, inducing fission. The fission products deposit energy-producing, detectable electron-hole pairs. The high energy released in the fission reaction indicates that noise discrimination in such a device has the potential to be excellent. Schottky devices were fabricated using a chemical deposition coating technique to deposit UO2 layers a few microns thick on a sapphire substrate. Schottky devices have also been made using a single crystal from UO2 samples approximately 500 microns thick. Neutron sensitivity simulations have been performed using GEANT4. Neutron sensitivity for the Schottky devices was tested experimentally using a 252Cf source.

Kruschwitz, Craig A.; Mukhopadhyay, Sanjoy; Schwellenbach, David; Meek, Thomas; Shaver, Brandon; Cunningham, Taylor; Auxier, Jerrad Philip

2014-09-01

420

The Uranium industry - yesterday, today, and tomorrow  

Microsoft Academic Search

This article is an edited version of a speech given by Thomas C. Pool, Vice-President of NUEXCO Information Services, at the US Council For Energy Awareness' Uranium Seminar 1993, held October 3-6, 1993, in Tucson, Arizona. In conclusion the author asks where can utilities go for their future needs In short, Canada is, and will be, the world's foremost source

Pool

1993-01-01

421

Production of uranium ore in capitalist countries  

Microsoft Academic Search

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

N. I. Chesnokov; V. G. Ivanov

1973-01-01

422

National Uranium Resource Evaluation: Marfa Quadrangle, Texas  

SciTech Connect

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

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

1982-09-01

423

Radiological health aspects of uranium milling  

SciTech Connect

This report describes the operation of conventional and unconventional uranium milling processes, the potential for occupational exposure to ionizing radiation at the mill, methods for radiological safety, methods of evaluating occupational radiation exposures, and current government regulations for protecting workers and ensuring that standards for radiation protection are adhered to. In addition, a survey of current radiological health practices is summarized.

Fisher, D.R.; Stoetzel, G.A.

1983-05-01

424

The extraction of uranium by amidoximated orlon  

Microsoft Academic Search

The nitrile groups in polyacrylonitrile (Orlon) fabric were converted to amidoxime groups to produce an amidoximated orlon fabric. The amidoximated fabric was evaluated for its ability to extract uranium from aqueous solution with a wide range of temperature and pH values. The conversion of nitrile groups to amidoxime groups was simple and relatively inexpensive. In general, the modified orlon fabric

S. Katragadda; H. D. Gesser; A. Chow

1997-01-01

425

Changing scene for uranium in Canada  

Microsoft Academic Search

Canada, for 20 yr, has had the popular image of being the fortunate possessor of large reserves of a strategic mineral fuel and possessor of a producing industry born in a boom atmosphere, impatiently awaiting and preparing for the nuclear future to be realized. Shortly after the peak production year of 1959, the uranium industry experienced a rapid decline, one

OBrien

1976-01-01

426

Pattern recognition applied to uranium prospecting  

Microsoft Academic Search

PATTERN recognition techniques provide one way of uniting quantitative and descriptive geologic data for mineral prospecting. A quantified decision process using computer-selected patterns of geologic data has the potential of selecting areas with undiscovered deposits of uranium or other minerals. When a natural resource is mined more rapidly than it is discovered, its continued production becomes increasingly difficult. For example,

P. L. Briggs

1977-01-01

427

Performance of a uranium liquid argon calorimeter  

SciTech Connect

We present results on the performance of a uranium and liquid argon calorimeter in the NW test beam at Fermilab. We describe the calorimeter, and discuss its performance with electrons, pions and muons from 10 GeV to 150 GeV. The performance perameters measured include response, linearity, resolution, compensation, and e/..pi.. separation.

Tuts, P.M.

1986-01-01

428

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

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

Burns, Peter C.

2004-12-01

429

Phosphate Barriers for Immobilization of Uranium Plumes  

SciTech Connect

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

Icenhower, Jonathan P.; Burns, Peter C.

2005-06-01

430

Uranium, thorium, potassium abundances in Venus rocks  

NASA Astrophysics Data System (ADS)

The results of a determination of natural radioactive elements in Venusian rocks at the landing sites of Vega 1 and Vega 2 show that their chemical composition is close to tholeitic basalts and gabbro of the earth crust. A short description of equipment and the gamma-spectrometry method of the determination of uranium, thorium and potassium concentration in rocks are given.

Surkov, Y. A.; Kirnozov, F. F.; Sobornov, O. P.; Glazov, V. N.; Dunchenko, A. G.; Tatsij, L. P.

1986-02-01

431

Bernabe Montano uranium deposit, Sandoval County  

SciTech Connect

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

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

1980-01-01

432

Safe Operating Procedure SAFETY PROTOCOL: URANIUM  

E-print Network

Properties of thorium-231, thorium-234, and protactinium-234m are included here because these radionuclides accompany the uranium decays. Source: Argonne National Laboratory, EVS ­ HHFS, August 2005 UNL Environmental Health and Safety · (402) 472-4925 · http://ehs.unl.edu #12;At UNL several of the research activities

Farritor, Shane

433

The multiphoton ionization of uranium hexafluoride  

SciTech Connect

Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF{sub 6} have been conducted using focused light from the Nd:YAG laser fundamental ({lambda}=1064 nm) and its harmonics ({lambda}=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF{sub x}{sup +} fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U{sup n+} ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U{sup 2+}) intensity is much greater than that of the singly-charged uranium ion (U{sup +}). For the case of the tunable dye laser experiments, the U{sup n+} (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U{sup 2+} ion and the absence or very small intensities of UF{sub x}{sup +} fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule.

Armstrong, D.P. (Oak Ridge K-25 Site, TN (United States). UEO Enrichment Technical Operations Div.) [Oak Ridge K-25 Site, TN (United States). UEO Enrichment Technical Operations Div.

1992-05-01

434

A METHOD FOR ROLLING URANIUM FOIL  

Microsoft Academic Search

Uranium-buttons may be rolled in a simple process by breaking and ; firing, plating, annealing at 600 deg C for 1\\/2 hr in a low pressure vacuum ; furnace, rolling immediately while still hot and then annealing. If cross ; rolling is done, the piece can be given two passes 90 deg to each other at the ; same reduction

Barnard; G. L. Jr

1947-01-01

435

Uranium on the Checkerboard: Crisis at Crownpoint  

ERIC Educational Resources Information Center

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

Barry, Tom; Wood, Beth

1978-01-01

436

Thermophysical properties of gas phase uranium tetrafluoride  

NASA Technical Reports Server (NTRS)

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

Watanabe, Yoichi; Anghaie, Samim

1993-01-01

437

Magnetic Properties of Intermetallic Uranium Compounds.  

National Technical Information Service (NTIS)

Magnetic properties of intermetallic uranium compounds have been investigated. The magnetic properties were studied at zero pressure in fields up to 35T. Their pressure dependences were investigated at pressures up to 8kbar in fields up to 10T. Specific h...

P. H. Frings

1984-01-01

438

National Uranium Resource Evaluation: Laredo Quadrangle, Texas  

SciTech Connect

The Laredo Quadrangle, Texas, was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for the occurrence of uranium deposits. The areas were delineated in accordance with criteria established by the National Uranium Resource Evaluation program sponsored by the US Department of Energy. Surface studies included investigations of uranium occurrences described in the literature, location of aerial radiometric anomalies, outcrop studies, and followup of hydrogeochemical and stream-sediment reconnaissance data. Subsurface evaluation of selected geologic units was accomplished by using electric and gamma-ray well logs to construct maps and cross sections. An environment favorable for Texas roll-type sandstone uranium deposits is identified in 62 areas in the Goliad, Oakville, Catahoula, Frio, and Whitsett Formations. The Midway Group; the Reklaw, Weches, Cook Mountain, Caddell, Wellborn, Manning, Vicksburg, and Anahuac Formations; the Chusa Member of the Catahoula Formation; the Fleming, Uvalde, Lissie, and Beaumont Formations; and river-terrace deposits and deposits of recent age are considered unfavorable. The Yegua, Sparta, Laredo, and Queen City Formations; the El Pico Clay; the Bigford and Carrizo Formations; the Wilcox Group; and the Escondido, Olmos, and San Miguel Formations were examined but not evaluated.

Cherepon, A.J.; Stauber, A.J.

1982-08-01

439

Uranium geochemistry in groundwater from tertiary sediments  

Microsoft Academic Search

Dissolved U concentrations and activity ratios (ARs) of the U isotopes in the 238 U decay series were measured in ground and surface waters as part of an investigation to delineate the water quality in a proposed uranium mining area of northwest Nebraska. In oxidizing groundwaters from 67 wells completed in the Tertiary sediments, increasing U concentrations in the direction

Roy F. Spalding; A. Douglas Druliner; Lowell S. Whiteside; Arthur W. Struempler

1984-01-01

440

MEETING REPORTS: SRP Scientific Meeting: Depleted Uranium  

Microsoft Academic Search

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

David Kestell

2002-01-01

441

Depleted Uranium: A Tragedy of the Commons  

Microsoft Academic Search

The Tragedy of the Commons parable (Hardin, 1968) is contrasted with a social catharsis concept called the Comedy of Community (Levine, 1986) as both pertain to environmental and health concerns regarding the use of depleted uranium (DU). The origin, nature, and exposure risks of DU are explored. A theory of justice model (Sheppard, Lewicki, & Minton, 1992) is implemented to

Christina E. Larson

1996-01-01

442

The Quest for the Heaviest Uranium Isotope  

E-print Network

We study Uranium isotopes and surrounding elements at very large neutron number excess. Relativistic mean field and Skyrme-type approaches with different parametrizations are used in the study. Most models show clear indications for isotopes that are stable with respect to neutron emission far beyond N=184 up to the range of around N=258.

S. Schramm; D. Gridnev; D. V. Tarasov; V. N. Tarasov; W. Greiner

2011-07-06

443

Uranium loans: Delaying the day of reckoning  

SciTech Connect

Spot market volume so far this year, by NUKEM's estimates, comes to just under 11 million lbs. It appears that existing loans are either being extended, or paid back with material borrowed from other sources. Therefore, there has been no significant amount of purchases on the spot market to pay back borrowed uranium. How do we know the loans have not been paid back with spot purchases For one thing, the amount of uranium loans outstanding has increased. According to our current survey, there may now be as much as 32 million lbs U3O8 equivalent in outstanding loans. At current prices, it's cheaper to borrow than to buy uranium. So borrowers are gambling that prices will remain low for some time, allowing them to delay repayment of the loans. Borrowers then, in essence, are delaying the day of reckoning on these loans. How long they can do so is anyone's guess. As long as uranium is in abundance and utilities remain willing to lend it out, loan activity will likely remain at or near current levels. But when supplies tighten and the market swings in a more positive direction, borrowers may get caught scrambling to repay their loans as quickly as possible.

Not Available

1993-09-01

444

Understanding Uranium Behavior in a Reduced Aquifer  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

445

RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION  

SciTech Connect

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

Lascola, R

2008-10-29

446

Geological and geochemical aspects of uranium deposits. A selected, annotated bibliography  

Microsoft Academic Search

A bibliography of 479 references encompassing the fields of uranium and thorium geochemistry and mineralogy, geology of uranium deposits, uranium mining, and uranium exploration techniques has been compiled by the Ecological Sciences Information Center of Oak Ridge National Laboratory. The bibliography was produced for the National Uranium Resource Evaluation Program, which is funded by the Grand Junction Office of the

P. A. Garland; J. M. Thomas; M. L. Brock; E. W. Daniel

1980-01-01

447

Differential geochemical mobility of uranium, thorium, and potassium used as geologic environment indicators and explorations tools  

Microsoft Academic Search

Uranium and potassium are easily leached from tuffaceous rocks, although thorium is not. Transport efficiency is higher for potassium than uranium. Uranium is immobilized by reduction or complexing. Potassium tends to be more thoroughly flushed, although it may be retained on clays and stabilized during diagenesis. Uranium and potassium tend to be separated during uranium precipitation. Organic-rich shales and uraniferous

Philip C. Goodell

1986-01-01

448

DYNAMIC PROPERTIES OF SHOCK LOADED THIN URANIUM FOILS  

SciTech Connect

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium spall targets, from deformation to complete spall or separation at the higher velocities. Dynamic measurements of the uranium target free surface velocities were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles were similar for the two types of uranium, but spall strengths (estimated from the magnitude of the pull-back signal) are higher for the high-purity cast uranium. Velocity profiles and microstructural evidence of spall from the sectioned uranium targets are presented.

Robbins, D. L. (David L.); Kelly, A. M. (Anna Marie); Alexander, D. J. (David J.); Hanrahan, R. J. (Robert J.); Snow, R. C. (Ronny C.); Gehr, R. J. (Russell J.); Rupp, Ted Dean,; Sheffield, S. A. (Stephen A.); Stahl, D. B. (David B.)

2001-01-01

449

Dynamic Properties of Shock Loaded Thin Uranium Foils  

NASA Astrophysics Data System (ADS)

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium targets, from deformation to complete spall or separation at the higher velocities. Dynamic measurements of the uranium target free surface velocities were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles were similar for the two types of uranium, but spall strengths (estimated from the magnitude of the pull-back signal) are higher for the high-purity cast uranium. Velocity profiles and microstructural evidence of spall from the sectioned uranium targets are presented.

Robbins, David L.; Kelly, Ann M.; Alexander, David J.; Hanrahan, Robert J.; Snow, Ronny C.; Gehr, Russell J.; Rupp, Ted D.; Sheffield, Stephen A.; Stahl, David B.

2002-07-01

450

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

USGS Publications Warehouse

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

Finch, Warren Irvin

1996-01-01

451

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

SciTech Connect

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

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

1983-04-01

452

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

PubMed

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

Baumann, Nils; Arnold, Thuro; Haferburg, Gtz

2014-06-01

453

Uranium Powder Production Via Hydride Formation and Alpha Phase Sintering of Uranium and Uranium-zirconium Alloys for Advanced Nuclear Fuel Applications  

E-print Network

mm. The resulting uranium powder was pressed into pellets of various compositions (DU, DU-10Zr, DU-Mg, DU-10Zr-Mg) and heated to approximately 650?C, just below the alphabeta phase transition of uranium. The dimensions of the pellets were measured...

Garnetti, David J.

2010-07-14

454

Distillation modeling for a uranium refining process  

SciTech Connect

As part of the spent fuel treatment program at Argonne National Laboratory, a vacuum distillation process is being employed for the recovery of uranium following an electrorefining process. Distillation of a salt electrolyte, containing a eutectic mixture of lithium and potassium chlorides, from uranium is achieved by a simple batch operation and is termed {open_quotes}cathode processing{close_quotes}. The incremental distillation of electrolyte salt will be modeled by an equilibrium expression and on a molecular basis since the operation is conducted under moderate vacuum conditions. As processing continues, the two models will be compared and analyzed for correlation with actual operating results. Possible factors that may contribute to aberrations from the models include impurities at the vapor-liquid boundary, distillate reflux, anomalous pressure gradients, and mass transport phenomena at the evaporating surface. Ultimately, the purpose of either process model is to enable the parametric optimization of the process.

Westphal, B.R.

1996-03-01

455

Profile of World Uranium Enrichment Programs-2009  

SciTech Connect

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 use as fuel for nuclear reactors to generate electricity. However, the same equipment used to produce LEU for nuclear reactor fuel can also be used to produce HEU for weapons. Safeguards at an enrichment plant are the array of assurances and verification techniques that ensure uranium is not diverted or enriched to HEU. There are several techniques for enriching uranium. The two most prevalent are gaseous diffusion, which uses older technology and requires a lot of energy, and gas centrifuge separation, which uses more advanced technology and is more energy efficient. Gaseous diffusion plants (GDPs) provide about 40% of current world enrichment capacity but are being phased out as newer gas centrifuge enrichment plants (GCEPs) are constructed. Estimates of current and future enrichment capacity are always approximate, due to the constant upgrades, expansions, and shutdowns occurring at enrichment plants, largely determined by economic interests. Currently, the world enrichment capacity is approximately 56 million kilogram separative work units (SWU) per year, with 22.5 million in gaseous diffusion and more than 33 million in gas centrifuge plants. Another 34 million SWU/year of capacity is under construction or planned for the near future, almost entirely using gas centrifuge separation. Other less-efficient techniques have also been used in the past, including electromagnetic and aerodynamic separations, but these are considered obsolete, at least from a commercial perspective. Laser isotope separation shows promise as a possible enrichment technique of the future but has yet to be demonstrated commercially. In the early 1980s, six countries developing gas centrifuge technology (United States, United Kingdom, Germany, the Netherlands, Japan, and Australia) along with the International Atomic Energy Agency and the European Atomic Energy Community began developing effective safeguards techniques for GCEPs. This effort was known as the Hexapartite Safeguards Project (HSP). The HSP had the goal of maximizing safeguards effectiveness while minimizing the cost to the operator and inspectorate, and adopted several recommendations, such as the acceptance of limited-frequency unannounced access inspections in cascade halls, and the use of nondestructive assay measurements and tamper-indicating seals. While only the HSP participants initially committed to implementing all the measures of the approach, it has been used as a model for the safeguards applied to GCEPs in additional states. Uranium enrichment capacity has continued to expand on all fronts in the last few years. GCEP capacity is expanding in anticipation of the eventual shutdown of the less-efficient GDPs, the termination of the U.S.-Russia HEU blend-down program slated for 2013, and the possible resurgence of nuclear reactor construction as part of an expected 'Nuclear Renaissance'. Overall, a clear trend in the world profile of uranium enrichment plant operation is the continued movement towards multinational projects driven by commercial and economic interests. Along this vein, the safeguards community is continuing to develop new safeguards techniques and technologies that are not overly burdensome to enrichment plant operators while delivering more effective and efficient results. This report provides a snapshot overview of world enrichment capacity in 2009, including profiles of the uranium enrichment programs of individual states. It is a revision of a 2007 report on the same topic; significant changes in world enrichment programs between the previous and current reports are emphasized. It is based entirely on open-source information, which is dependent on published sources and may theref

Laughter, Mark D [ORNL

2009-04-01

456

Assessment of Preferred Depleted Uranium Disposal Forms  

SciTech Connect

The Department of Energy (DOE) is in the process of converting about 700,000 metric tons (MT) of depleted uranium hexafluoride (DUF6) containing 475,000 MT of depleted uranium (DU) to a stable form more suitable for long-term storage or disposal. Potential conversion forms include the tetrafluoride (DUF4), oxide (DUO2 or DU3O8), or metal. If worthwhile beneficial uses cannot be found for the DU product form, it will be sent to an appropriate site for disposal. The DU products are considered to be low-level waste (LLW) under both DOE orders and Nuclear Regulatory Commission (NRC) regulations. The objective of this study was to assess the acceptability of the potential DU conversion products at potential LLW disposal sites to provide a basis for DOE decisions on the preferred DU product form and a path forward that will ensure reliable and efficient disposal.

Croff, A.G.; Hightower, J.R.; Lee, D.W.; Michaels, G.E.; Ranek, N.L.; Trabalka, J.R.

2000-06-01

457

Statistical data of the uranium industry  

SciTech Connect

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

none,

1980-01-01

458

Uranium series dating of Allan Hills ice  

NASA Technical Reports Server (NTRS)

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

Fireman, E. L.

1986-01-01

459

Boiling water reactor uranium utilization improvement potential  

SciTech Connect

This report documents the results of design and operational simulation studies to assess the potential for reduction of BWR uranium requirements. The impact of the improvements on separative work requirements and other fuel cycle requirements also were evaluated. The emphasis was on analysis of the improvement potential for once-through cycles, although plutonium recycle also was evaluated. The improvement potential was analyzed for several design alternatives including axial and radial natural uranium blankets, low-leakage refueling patterns, initial core enrichment distribution optimization, reinsert of initial core discharge fuel, preplanned end-of-cycle power coastdown and feedwater temperature reduction, increased discharge burnup, high enrichment discharge fuel rod reassembly and reinsert, lattice and fuel bundle design optimization, coolant density spectral shift with flow control, reduced burnable absorber residual, boric acid for cold shutdown, six-month subcycle refueling, and applications of a once-through thorium cycle design and plutonium recycle.

Wei, P.; Crowther, R.L.; Fennern, L.E.; Savoia, P.J.; Specker, S.R.; Tilley, R.M.; Townsend, D.B.; Wolters, R.A.

1980-06-01

460

Uranium settling rates in SRS waste supernate  

SciTech Connect

The evaporation of SRS High Level Waste supernate is accompanied by a decrease in the solubility of uranium, and thus uranium precipitates as the complex compound usually referred to as Na{sub 2}U{sub 2}O{sub 7}. The precipitated Na{sub 2}U{sub 2}O{sub 7} and other precipitated solids will settle through the concentrated evaporator product at a rate determined by Stokes` Law. The quantities which make up Stokes` Law can all be determined from physical measurements, and the settling rate thus determined for any particle size or, by extension, for a distribution of particle sizes. Reported here are the measurement of the variables in Stokes` Law for Na{sub 2}U{sub 2}O{sub 7}.

Karraker, D.G.

1994-01-26

461

In-line assay monitor for uranium hexafluoride  

DOEpatents

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

Wallace, S.A.

1980-03-21

462

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

SciTech Connect

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

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

1982-09-01

463

Measurements of uranium mass confined in high density plasmas  

NASA Technical Reports Server (NTRS)

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

Stoeffler, R. C.

1976-01-01

464

Depleted-uranium recovery from and cleaning of target sands  

SciTech Connect

This patent describes a method of removing uranium and its oxidation products from target sands and consists of: (a) providing a container means which can be heated; (b) adding uranium-containing target sands to the container; (c) adding a salt mixture comprising at least 70 weight percent of a salt selected from the group consisting of nitrates of magnesium, calcium, potassium, sodium, and lithium to the container; (d) heating the target sands and the salt mixture together to fuse the salt to convert the uranium to uranium oxidation products; (e) adding water to dissolve the salt component into aqueous solution and removing the aqueous solution; (f) adding nitric acid to dissolve the uranium oxidation products into aqueous nitric acid solution; and (g) rinsing the target sands with water washing out the dissolved uranium oxidation products.

Elliott, G.R.B.

1986-02-04

465

Extraction behavior of uranium(VI) with polyurethane foam  

SciTech Connect

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

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

1992-10-01

466

Understanding Uranium Migration in Hard Rocks  

Microsoft Academic Search

\\u000a Uranium is a major radioactive constituent of spent nuclear fuel and high-level radioactive waste. However, its migration\\u000a behaviour in crystalline rocks is still inadequately understood. This paper describes the results of controlled laboratory\\u000a migration experiments and attempts made to simulate them using numerical models. Initial models employing generic information\\u000a in blind predictions are progressively enhanced by data-supported interpretation. Such an

W. Eberhard Falck; David Read; S. Black; D. Thornley; M. Markovaara-Koivisto; M. Siitari-Kauppi

467

Plutonium Uranium Extraction Facility Documented Safety Analysis  

SciTech Connect

This document provides the documented safety analysis (DSA) and Central Plateau Remediation Project (CP) requirements that apply to surveillance and maintenance (S&M) activities at the Plutonium-Uranium Extraction (PUREX) facility. This DSA was developed in accordance with DOE-STD-1120-98, ''Integration of Environment, Safety, and Health into Facility Disposition Activities''. Upon approval and implementation of this document, the current safety basis documents will be retired.

DODD, E.N.

2003-10-08

468

Energy balance for uranium recovery from seawater  

SciTech Connect

The energy return on investment (EROI) of an energy resource is the ratio of the energy it ultimately produces to the energy used to recover it. EROI is a key viability measure for a new recovery technology, particularly in its early stages of development when financial cost assessment would be premature or highly uncertain. This paper estimates the EROI of uranium recovery from seawater via a braid adsorbent technology. In this paper, the energy cost of obtaining uranium from seawater is assessed by breaking the production chain into three processes: adsorbent production, adsorbent deployment and mooring, and uranium elution and purification. Both direct and embodied energy inputs are considered. Direct energy is the energy used by the processes themselves, while embodied energy is used to fabricate their material, equipment or chemical inputs. If the uranium is used in a once-through fuel cycle, the braid adsorbent technology EROI ranges from 12 to 27, depending on still-uncertain performance and system design parameters. It is highly sensitive to the adsorbent capacity in grams of U captured per kg of adsorbent as well as to potential economies in chemical use. This compares to an EROI of ca. 300 for contemporary terrestrial mining. It is important to note that these figures only consider the mineral extraction step in the fuel cycle. At a reference performance level of 2.76 g U recovered per kg adsorbent immersed, the largest energy consumers are the chemicals used in adsorbent production (63%), anchor chain mooring system fabrication and operations (17%), and unit processes in the adsorbent production step (12%). (authors)

Schneider, E.; Lindner, H. [The University of Texas, 1 University Station C2200, Austin, TX 78712 (United States)

2013-07-01

469

Uranium enrichment export control guide: Gaseous diffusion  

SciTech Connect

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

Not Available

1989-09-01