WorldWideScience

Sample records for natural uranium conversion

  1. Uranium conversion; Conversion de l`uranium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    This booklet is a presentation of the activities of the Comurhex company, created in 1971 and which became a 100% Cogema`s daughter company in 1992. The Comurhex company is in charge of the conversion of natural uranium into gaseous uranium hexafluoride (UF{sub 6}). The two steps of the conversion operation are performed in the Malvesi and Pierrelatte (France) industrial sites and represent 31% (14000 t/year) of the uranium conversion capacity of western countries. The refining and UF{sub 4} production (Malvesi) and the UF{sub 6} fabrication (Pierrelatte) processes are described. Comurhex is also one of the few companies in the world which produces UF{sub 6} from the uranium of spent fuels. (J.S.)

  2. Uranium Conversion & Enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-06

    The isotopes of uranium that are found in nature, and hence in ‘fresh’ Yellowcake’, are not in relative proportions that are suitable for power or weapons applications. The goal of conversion then is to transform the U3O8 yellowcake into UF6. Conversion and enrichment of uranium is usually required to obtain material with enough 235U to be usable as fuel in a reactor or weapon. The cost, size, and complexity of practical conversion and enrichment facilities aid in nonproliferation by design.

  3. Uranium conversion; Urankonvertering

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina [Swedish Defence Research Agency (FOI), Stockholm (Sweden)

    2006-03-15

    FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF{sub 6} and UF{sub 4} are present require equipment that is made of corrosion resistant material.

  4. Model of a Generic Natural Uranium Conversion Plant ? Suggested Measures to Strengthen International Safeguards

    Energy Technology Data Exchange (ETDEWEB)

    Raffo-Caiado, Ana Claudia [ORNL; Begovich, John M [ORNL; Ferrada, Juan J [ORNL

    2009-11-01

    This is the final report that closed a joint collaboration effort between DOE and the National Nuclear Energy Commission of Brazil (CNEN). In 2005, DOE and CNEN started a collaborative effort to evaluate measures that can strengthen the effectiveness of international safeguards at a natural uranium conversion plant (NUCP). The work was performed by DOE s Oak Ridge National Laboratory and CNEN. A generic model of a NUCP was developed and typical processing steps were defined. Advanced instrumentation and techniques for verification purposes were identified and investigated. The scope of the work was triggered by the International Atomic Energy Agency s 2003 revised policy concerning the starting point of safeguards at uranium conversion facilities. Prior to this policy only the final products of the uranium conversion plant were considered to be of composition and purity suitable for use in the nuclear fuel cycle and therefore, subject to the IAEA safeguards control. DOE and CNEN have explored options for implementing the IAEA policy, although Brazil understands that the new policy established by the IAEA is beyond the framework of the Quadripartite Agreement of which it is one of the parties, together with Argentina, the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC) and the IAEA. Two technical papers on this subject were published at the 2005 and 2008 INMM Annual Meetings.

  5. Model of a Generic Natural Uranium Conversion Plant ? Suggested Measures to Strengthen International Safeguards

    Energy Technology Data Exchange (ETDEWEB)

    Raffo-Caiado, Ana Claudia [ORNL; Begovich, John M [ORNL; Ferrada, Juan J [ORNL

    2009-11-01

    This is the final report that closed a joint collaboration effort between DOE and the National Nuclear Energy Commission of Brazil (CNEN). In 2005, DOE and CNEN started a collaborative effort to evaluate measures that can strengthen the effectiveness of international safeguards at a natural uranium conversion plant (NUCP). The work was performed by DOE s Oak Ridge National Laboratory and CNEN. A generic model of a NUCP was developed and typical processing steps were defined. Advanced instrumentation and techniques for verification purposes were identified and investigated. The scope of the work was triggered by the International Atomic Energy Agency s 2003 revised policy concerning the starting point of safeguards at uranium conversion facilities. Prior to this policy only the final products of the uranium conversion plant were considered to be of composition and purity suitable for use in the nuclear fuel cycle and therefore, subject to the IAEA safeguards control. DOE and CNEN have explored options for implementing the IAEA policy, although Brazil understands that the new policy established by the IAEA is beyond the framework of the Quadripartite Agreement of which it is one of the parties, together with Argentina, the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC) and the IAEA. Two technical papers on this subject were published at the 2005 and 2008 INMM Annual Meetings.

  6. Validation of gamma-ray detection techniques for safeguards monitoring at natural uranium conversion facilities

    Science.gov (United States)

    Dewji, S. A.; Lee, D. L.; Croft, S.; Hertel, N. E.; Chapman, J. A.; McElroy, R. D.; Cleveland, S.

    2016-07-01

    Recent IAEA circulars and policy papers have sought to implement safeguards when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under the revised policy, IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UO2(NO3)2) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. Nondestructive assay techniques using gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely way. This work investigated gamma-ray signatures of uranyl nitrate circulating in the UNCLE facility and evaluated various gamma-ray detector sensitivities to uranyl nitrate. These detector validation activities include assessing detector responses to the uranyl nitrate gamma-ray signatures for spectrometers based on sodium iodide, lanthanum bromide, and high-purity germanium detectors. The results of measurements under static and dynamic operating conditions at concentrations ranging from 10-90 g U/L of natural uranyl nitrate are presented. A range of gamma-ray lines is

  7. Validation of gamma-ray detection techniques for safeguards monitoring at natural uranium conversion facilities

    Energy Technology Data Exchange (ETDEWEB)

    Dewji, S.A., E-mail: dewjisa@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS-6335, Oak Ridge, TN 37831-6335 (United States); Lee, D.L.; Croft, S. [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS-6335, Oak Ridge, TN 37831-6335 (United States); Hertel, N.E. [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS-6335, Oak Ridge, TN 37831-6335 (United States); Nuclear and Radiological Engineering Program, Georgia Institute of Technology, 770 State Street, Atlanta, GA 30332-0745 (United States); Chapman, J.A.; McElroy, R.D.; Cleveland, S. [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS-6335, Oak Ridge, TN 37831-6335 (United States)

    2016-07-01

    Recent IAEA circulars and policy papers have sought to implement safeguards when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under the revised policy, IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UO{sub 2}(NO{sub 3}){sub 2}) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. Nondestructive assay techniques using gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely way. This work investigated gamma-ray signatures of uranyl nitrate circulating in the UNCLE facility and evaluated various gamma-ray detector sensitivities to uranyl nitrate. These detector validation activities include assessing detector responses to the uranyl nitrate gamma-ray signatures for spectrometers based on sodium iodide, lanthanum bromide, and high-purity germanium detectors. The results of measurements under static and dynamic operating conditions at concentrations ranging from 10–90 g U/L of natural uranyl nitrate are presented. A range of

  8. Sensitivity analysis of high resolution gamma-ray detection for safeguards monitoring at natural uranium conversion facilities

    Science.gov (United States)

    Dewji, S. A.; Croft, S.; Hertel, N. E.

    2017-03-01

    Under the policies proposed by recent International Atomic Energy Agency (IAEA) circulars and policy papers, implementation of safeguards exists when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed in previous work to develop and validate gamma-ray nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UO2(NO3)2) solution exiting solvent extraction was identified as a key measurement point (KMP). Passive nondestructive assay techniques using high resolution gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely manner. Building upon the aforementioned previous validation work on detector sensitivity to varying concentrations of uranyl nitrate via a series of dilution measurements, this work investigates detector response parameter sensitivities to gamma-ray signatures of uranyl nitrate. The full energy peak efficiency of a detection system is dependent upon the sample, geometry, absorption, and intrinsic efficiency parameters. Perturbation of these parameters translates into corresponding variations of the 185.7 keV peak area of the 235U in uranyl nitrate. Such perturbations in the assayed signature impact the quality or versatility of the safeguards conclusions drawn. Given the potentially high throughput of uranyl nitrate in NUCPs, the ability to assay 1 SQ of material requires uncertainty «1%. Accounting for

  9. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed....

  10. 31 CFR 540.309 - Natural uranium.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Natural uranium. 540.309 Section 540... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.309 Natural uranium. The term natural uranium means uranium found...

  11. Natural gas conversion process

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    The experimental apparatus was dismantled and transferred to a laboratory space provided by Lawrence Berkeley Laboratory (LBL) which is already equipped with a high-ventilation fume hood. This will enable us to make tests at higher gas flow rates in a safe environment. Three papers presented at the ACS meeting in San Francisco (Symposium on Natural Gas Upgrading II) April 5--10, 1992 show that the goal of direct catalytic conversion of Methane into heavier Hydrocarbons in a reducing atmosphere is actively pursued in three other different laboratories. There are similarities in their general concept with our own approach, but the temperature range of the experiments reported in these recent papers is much lower and this leads to uneconomic conversion rates. This illustrates the advantages of Methane activation by a Hydrogen plasma to reach commercial conversion rates. A preliminary process flow diagram was established for the Integrated Process, which was outlined in the previous Quarterly Report. The flow diagram also includes all the required auxiliary facilities for product separation and recycle of the unconverted feed as well as for the preparation and compression of the Syngas by-product.

  12. 10 CFR Appendix J to Part 110 - Illustrative List of Uranium Conversion Plant Equipment and Plutonium Conversion Plant Equipment...

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Illustrative List of Uranium Conversion Plant Equipment and Plutonium Conversion Plant Equipment Under NRC Export Licensing Authority J Appendix J to Part 110.... 110, App. J Appendix J to Part 110—Illustrative List of Uranium Conversion Plant Equipment...

  13. Natural fractionation of uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Noordmann, Janine

    2015-01-24

    The topic of this thesis was the investigation of U (n({sup 238}U) / n({sup 235}U)) isotope variations in nature with a focus on samples (1) that represent the continental crust and its weathering products (i.e. granites, shales and river water) (2) that represent products of hydrothermal alteration on mid-ocean ridges (i.e. altered basalts, carbonate veins and hydrothermal water) and (3) from restricted euxinic basins (i.e. from the water column and respective sediments). The overall goal was to explore the environmental conditions and unravel the mechanisms that fractionate the two most abundant U isotopes, n({sup 238}U) and n({sup 235}U), on Earth.

  14. The re-enrichment of depleted uranium tails in the US versus de-conversion and disposal

    Energy Technology Data Exchange (ETDEWEB)

    Deinert, M.R.; Schneider, E.A. [Department of Mechancial Engineering, The University of Texas at Austin, 1 University Station, C2200, Austin, TX 1 University Station, C2200 (United States)

    2009-06-15

    International consumption of uranium currently outpaces production by nearly a factor of two. Secondary supplies from dismantled nuclear weapons, along with civilian and governmental stockpiles, are being used to make up the difference but supplies are limited. However, large amounts of {sup 235}U are contained in the depleted uranium tails left over from past uranium enrichment. The usability of these inhomogeneous uranium supplies depends on their isotopics and the cost of SWU. In the US the current plan is to de-convert depleted uranium tails and to dispose of them in a low level nuclear repository [1]. We present data on cost of re-enriching depleted uranium tails in the US inventory and compare its cost to the disposal option currently under consideration. Historically, the majority of commercial nuclear power has been generated using light-water reactors (LWRs) burning low enriched uranium. While research into technologies that could close the nuclear fuel cycle continues in the US and elsewhere, the maturity and economic competitiveness of LWRs will make them a major presence for decades to come. Because of this, global demand for uranium is likely to remain strong and its future price uncertain, with acceptable alternatives to mined natural uranium being of significant interest as a result. At present, substitutes include down-blending of highly enriched uranium, uranium released from government or utility stockpiles, enrichable depleted uranium (DU) and reprocessable uranium (RU) from spent LWR fuel (SF) [2]. The decision of whether to mine fresh uranium or exploit alternative sources is largely a matter of economics. Depleted uranium stockpiles have a variable {sup 235}U composition and would typically require additional enrichment beyond what is needed for manufacturing LWR fuel from natural uranium. As a result, the price of using DU depends on the costs of enrichment, DU cylinder transport from storage to the enrichment plant, UF{sub 6} tails storage

  15. Influence of uranium on bacterial communities: a comparison of natural uranium-rich soils with controls.

    Directory of Open Access Journals (Sweden)

    Laure Mondani

    Full Text Available 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.

  16. Study of Natural Background Radiation around Gurvanbulag Uranium Deposit Area

    Science.gov (United States)

    Enkhbat, N.; Norov, N.; Bat-Erdene, B.; Khuukhenkhuu, G.; Otgooloi, B.

    2009-03-01

    In this work, we will show the study of natural background radiation level around the Gurvanbulag (GB) uranium deposit area in the eastern part of Mongolia. We collected environmental soil samples from 102 points around GB Uranium deposit. Collected samples were measured by HPGe gamma spectrometer at Nuclear Research Center, National University of Mongolia. The averaged activity concentrations of Ra-226, Th-232, K-40, and Cs-137 were 37.1, 29, 939, and 17.7 Bq/kg, respectively.

  17. Uranium Metal to Oxide Conversion by Air Oxidation –Process Development

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, A

    2001-12-31

    Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

  18. Gas Cooled, Natural Uranium, D20 Moderated Power Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, R.C.; Beasley, E.G.; DeBoer, T.K.; Evans, T.C.; Molino, D.F.; Rothwell, W.S.; Slivka, W.R.

    1956-08-01

    The attractiveness of a helium cooled, heavy water moderated, natural uranium central station power plant has been investigated. A fuel element has been devised which allows the D20 to be kept at a low pressure while the exit gas temperature is high. A preliminary cost analysis indicates that, using currently available materials, competitive nuclear power in foreign countries is possible.

  19. 49 CFR 173.434 - Activity-mass relationships for uranium and natural thorium.

    Science.gov (United States)

    2010-10-01

    ... natural thorium. 173.434 Section 173.434 Transportation Other Regulations Relating to Transportation....434 Activity-mass relationships for uranium and natural thorium. The table of activity-mass relationships for uranium and natural thorium are as follows: Thorium and uranium enrichment 1(Wt% 235 U...

  20. 10 CFR 40.66 - Requirements for advance notice of export shipments of natural uranium.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Requirements for advance notice of export shipments of natural uranium. 40.66 Section 40.66 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF SOURCE... natural uranium. (a) Each licensee authorized to export natural uranium, other than in the form of ore...

  1. Metabolomics identifies a biological response to chronic low-dose natural uranium contamination in urine samples.

    Science.gov (United States)

    Grison, Stéphane; Favé, Gaëlle; Maillot, Matthieu; Manens, Line; Delissen, Olivia; Blanchardon, Eric; Banzet, Nathalie; Defoort, Catherine; Bott, Romain; Dublineau, Isabelle; Aigueperse, Jocelyne; Gourmelon, Patrick; Martin, Jean-Charles; Souidi, Maâmar

    2013-01-01

    Because uranium is a natural element present in the earth's crust, the population may be chronically exposed to low doses of it through drinking water. Additionally, the military and civil uses of uranium can also lead to environmental dispersion that can result in high or low doses of acute or chronic exposure. Recent experimental data suggest this might lead to relatively innocuous biological reactions. The aim of this study was to assess the biological changes in rats caused by ingestion of natural uranium in drinking water with a mean daily intake of 2.7 mg/kg for 9 months and to identify potential biomarkers related to such a contamination. Subsequently, we observed no pathology and standard clinical tests were unable to distinguish between treated and untreated animals. Conversely, LC-MS metabolomics identified urine as an appropriate biofluid for discriminating the experimental groups. Of the 1,376 features detected in urine, the most discriminant were metabolites involved in tryptophan, nicotinate, and nicotinamide metabolic pathways. In particular, N-methylnicotinamide, which was found at a level seven times higher in untreated than in contaminated rats, had the greatest discriminating power. These novel results establish a proof of principle for using metabolomics to address chronic low-dose uranium contamination. They open interesting perspectives for understanding the underlying biological mechanisms and designing a diagnostic test of exposure.

  2. Fabrication of uranium dioxide fuel pellets in support of a SLOWPOKE-2 research reactor HEU to LEU core conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bergeron, A. [Aomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2014-07-01

    The International Centre for Environmental and Nuclear Sciences (ICENS) at the University of the West Indies in Jamaica operates a SLOWPOKE-2 research reactor that is currently fuelled with highly-enriched uranium (HEU). As part of the Global Threat Reduction Initiative, Atomic Energy of Canada Ltd. has been subcontracted to fabricate low-enriched uranium (LEU) fuel for the ICENS SLOWPOKE-2. The low enriched uranium core consists of a fuel cage containing uranium dioxide fuelled elements. This paper describes the fabrication of the low-enriched uranium dioxide fuel pellets for the SLOWPOKE-2 core conversion. (author)

  3. Conversion chimique du gaz naturel Chemical Conversion of Natural Gas

    Directory of Open Access Journals (Sweden)

    Chaumette P.

    2006-11-01

    Full Text Available Dans cet article sont passés en revue les travaux de recherche et développement et les procédés existants dans le domaine de la conversion chimique du gaz naturel. Les deux voies possibles, conversion directe du méthane et conversion indirecte, via le gaz de synthèse, sont présentées. Tant la préparation d'hydrocarbures utilisables comme carburants, que celle des composés de bases pour la pétrochimie ou la chimie sont évoquées. L'accent est mis sur l'étape clé du développement de chaque procédé qui, selon le produit visé, consiste en la mise au point d'un nouveau système catalytique, en un changement de la technologie du réacteur, ou en la mise au point d'une section fractionnement moins complexe. This article reviews the research and development work and the existing processes in the area of chemical conversion of natural gas. The two possible methods, direct conversion of methane and indirect conversion via synthesis gas, are discussed. The preparation of hydrocarbons that can be used as fuels and the production of building blocks for the petrochemical and chemical industries are both dealt with. The accent is placed on the key step in developing each process. Depending on the target product, this key step consists in working out a new catalytic system, changing reactor technology or engineering a less complex fractionation section.

  4. Energy Conversion in Protocells with Natural Nanoconductors

    Directory of Open Access Journals (Sweden)

    Jian Xu

    2012-01-01

    Full Text Available While much nanotechnology leverages solid-state devices, here we present the analysis of designs for hybrid organic-inorganic biomimetic devices, “protocells,” based on assemblies of natural ion channels and ion pumps, “nanoconductors,” incorporated into synthetic supported lipid bilayer membranes. These protocells mimic the energy conversion scheme of natural cells and are able to directly output electricity. The electrogenic mechanisms have been analyzed and designs were optimized using numerical models. The parameters that affect the energy conversion are quantified, and limits for device performance have been found using numerical optimization. The electrogenic performance is compared to conventional and emerging technologies and plotted on Ragone charts to allow direct comparisons. The protocell technologies summarized here may be of use for energy conversion where large-scale ion concentration gradients are available (such as the intersection of fresh and salt water sources or small-scale devices where low power density would be acceptable.

  5. Affective Embodied Conversational Agents for Natural Interaction

    OpenAIRE

    Cerezo, Eva; Baldassarri, Sandra; Hupont, Isabelle; Seron, Francisco J.

    2008-01-01

    This chapter presents a completely automated real-time character-based interface, where a scriptable affective humanoid 3D agent interacts with the user. Special care has been taken in making it possible multimodal natural user-agent interaction: communication is accomplished via text, image and voice (natural language). Our embodied agents are equipped with an emotional state which can be modified throughout the conversation with the user, and depends on the emotional state detected from the...

  6. Uranium Biomineralization By Natural Microbial Phosphatase Activities in the Subsurface

    Energy Technology Data Exchange (ETDEWEB)

    Taillefert, Martial [Georgia Tech Research Corporation, Atlanta, GA (United States)

    2015-04-01

    This project investigated the geochemical and microbial processes associated with the biomineralization of radionuclides in subsurface soils. During this study, it was determined that microbial communities from the Oak Ridge Field Research subsurface are able to express phosphatase activities that hydrolyze exogenous organophosphate compounds and result in the non-reductive bioimmobilization of U(VI) phosphate minerals in both aerobic and anaerobic conditions. The changes of the microbial community structure associated with the biomineralization of U(VI) was determined to identify the main organisms involved in the biomineralization process, and the complete genome of two isolates was sequenced. In addition, it was determined that both phytate, the main source of natural organophosphate compounds in natural environments, and polyphosphate accumulated in cells could also be hydrolyzed by native microbial population to liberate enough orthophosphate and precipitate uranium phosphate minerals. Finally, the minerals produced during this process are stable in low pH conditions or environments where the production of dissolved inorganic carbon is moderate. These findings suggest that the biomineralization of U(VI) phosphate minerals is an attractive bioremediation strategy to uranium bioreduction in low pH uranium-contaminated environments. These efforts support the goals of the SBR long-term performance measure by providing key information on "biological processes influencing the form and mobility of DOE contaminants in the subsurface".

  7. Standard specification for uranium oxides with a 235U content of less than 5 % for dissolution prior to conversion to nuclear-grade uranium dioxide

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This specification covers uranium oxides, including processed byproducts or scrap material (powder, pellets, or pieces), that are intended for dissolution into uranyl nitrate solution meeting the requirements of Specification C788 prior to conversion into nuclear grade UO2 powder with a 235U content of less than 5 %. This specification defines the impurity and uranium isotope limits for such urania powders that are to be dissolved prior to processing to nuclear grade UO2 as defined in Specification C753. 1.2 This specification provides the nuclear industry with a general standard for such uranium oxide powders. It recognizes the diversity of conversion processes and the processes to which such powders are subsequently to be subjected (for instance, by solvent extraction). It is therefore anticipated that it may be necessary to include supplementary specification limits by agreement between the buyer and seller. 1.3 The scope of this specification does not comprehensively cover all provisions for prevent...

  8. Natural gas conversion process. Sixth quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-01

    The experimental apparatus was dismantled and transferred to a laboratory space provided by Lawrence Berkeley Laboratory (LBL) which is already equipped with a high-ventilation fume hood. This will enable us to make tests at higher gas flow rates in a safe environment. Three papers presented at the ACS meeting in San Francisco (Symposium on Natural Gas Upgrading II) April 5--10, 1992 show that the goal of direct catalytic conversion of Methane into heavier Hydrocarbons in a reducing atmosphere is actively pursued in three other different laboratories. There are similarities in their general concept with our own approach, but the temperature range of the experiments reported in these recent papers is much lower and this leads to uneconomic conversion rates. This illustrates the advantages of Methane activation by a Hydrogen plasma to reach commercial conversion rates. A preliminary process flow diagram was established for the Integrated Process, which was outlined in the previous Quarterly Report. The flow diagram also includes all the required auxiliary facilities for product separation and recycle of the unconverted feed as well as for the preparation and compression of the Syngas by-product.

  9. 49 CFR 173.426 - Excepted packages for articles containing natural uranium or thorium.

    Science.gov (United States)

    2010-10-01

    ... uranium or thorium. 173.426 Section 173.426 Transportation Other Regulations Relating to Transportation....426 Excepted packages for articles containing natural uranium or thorium. A manufactured article in... or natural thorium, and its packaging, are excepted from the requirements in this subchapter...

  10. Calculation of parameters for inspection planning and evaluation: low enriched uranium conversion and fuel fabrication facilities

    Energy Technology Data Exchange (ETDEWEB)

    Reardon, P.T.; Mullen, M.F.; Harms, N.L.

    1981-02-01

    As part of Task C.35 (Calculation of Parameters for Inspection Planning and Evaluation) of the US Program of Technical Assistance to IAEA Safeguards, Pacific Northwest Laboratory has performed some quantitative analyses of IAEA inspection activities at low-enriched uranium (LEU) conversion and fuel fabrication facilities. This report presents the results and conclusions of those analyses. Implementation of IAEA safeguards at LEU conversion and fuel fabrication facilities must take into account a variety of practical problems and constraints. One of the key concerns is the problem of flow verification, especially product verification. The objective of this report is to help put the problem of flow verification in perspective by presenting the results of some specific calculations of inspection effort and probability of detection for various product measurement strategies. In order to provide quantitative information about the advantages and disadvantages of the various strategies, eight specific cases were examined.

  11. Exposure assessment of natural uranium from drinking water.

    Science.gov (United States)

    Jakhu, Rajan; Mehra, Rohit; Mittal, H M

    2016-12-08

    The uranium concentration in the drinking water of the residents of the Jaipur and Ajmer districts of Rajasthan has been measured for exposure assessment. The daily intake of uranium from the drinking water for the residents of the study area is found to vary from 0.4 to 123.9 μg per day. For the average uranium ingestion rate of 35.2 μg per day for a long term exposure period of 60 years, estimations have been made for the retention of uranium in different body organs and its excretion with time using ICRP's biokinetic model of uranium. Radioactive and chemical toxicity of uranium has been reported and discussed in detail in the present manuscript.

  12. Determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Le Cong; Tao, Chau Van; Thong, Luong Van; Linh, Duong Mong [University of Science Ho Chi Minh City (Viet Nam). Faculty of Physics and Engineering Physics; Dong, Nguyen Van [University of Science Ho Chi Minh City (Viet Nam). Faculty of Chemistry

    2011-08-15

    In this study, a simple procedure for the determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy is described. This procedure allows a sequential extraction polonium, uranium, thorium and radium radionuclides from the same sample in two to three days. It was tested and validated with the analysis of certified reference materials from the IAEA. (orig.)

  13. Low-Enriched Uranium Fuel Conversion Activities for the High Flux Isotope Reactor, Annual Report for FY 2011

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David G [ORNL; Cook, David Howard [ORNL; Freels, James D [ORNL; Griffin, Frederick P [ORNL; Ilas, Germina [ORNL; Sease, John D [ORNL; Chandler, David [ORNL

    2012-03-01

    This report describes progress made during FY11 in ORNL activities to support converting the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum (UMo) alloy. With both radial and axial contouring of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in performance to users from the current levels achieved with HEU fuel. Studies are continuing to demonstrate that the fuel thermal safety margins can be preserved following conversion. Studies are also continuing to update other aspects of the reactor steady state operation and accident response for the effects of fuel conversion. Technical input has been provided to Oregon State University in support of their hydraulic testing program. The HFIR conversion schedule was revised and provided to the GTRI program. In addition to HFIR conversion activities, technical support was provided directly to the Fuel Fabrication Capability program manager.

  14. Preconceptual design studies and cost data of depleted uranium hexafluoride conversion plants

    Energy Technology Data Exchange (ETDEWEB)

    Jones, E

    1999-07-26

    One of the more important legacies left with the Department of Energy (DOE) after the privatization of the United States Enrichment Corporation is the large inventory of depleted uranium hexafluoride (DUF6). The DOE Office of Nuclear Energy, Science and Technology (NE) is responsible for the long-term management of some 700,000 metric tons of DUF6 stored at the sites of the two gaseous diffusion plants located at Paducah, Kentucky and Portsmouth, Ohio, and at the East Tennessee Technology Park in Oak Ridge, Tennessee. The DUF6 management program resides in NE's Office of Depleted Uranium Hexafluoride Management. The current DUF6 program has largely focused on the ongoing maintenance of the cylinders containing DUF6. However, the long-term management and eventual disposition of DUF6 is the subject of a Programmatic Environmental Impact Statement (PEIS) and Public Law 105-204. The first step for future use or disposition is to convert the material, which requires construction and long-term operation of one or more conversion plants. To help inform the DUF6 program's planning activities, it was necessary to perform design and cost studies of likely DUF6 conversion plants at the preconceptual level, beyond the PEIS considerations but not as detailed as required for conceptual designs of actual plants. This report contains the final results from such a preconceptual design study project. In this fast track, three month effort, Lawrence Livermore National Laboratory and Bechtel National Incorporated developed and evaluated seven different preconceptual design cases for a single plant. The preconceptual design, schedules, costs, and issues associated with specific DUF6 conversion approaches, operating periods, and ownership options were evaluated based on criteria established by DOE. The single-plant conversion options studied were similar to the dry-conversion process alternatives from the PEIS. For each of the seven cases considered, this report contains

  15. Standard guide for establishing a quality assurance program for uranium conversion facilities

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This guide provides guidance and recommended practices for establishing a comprehensive quality assurance program for uranium conversion facilities. 1.2 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 health and safety practices and determine the applicability of regulatory limitations prior to use. 1.3 The basic elements of a quality assurance program appear in the following order: FUNCTION SECTION Organization 5 Quality Assurance Program 6 Design Control 7 Instructions, Procedures & Drawings 8 Document Control 9 Procurement 10 Identification and Traceability 11 Processes 12 Inspection 13 Control of Measuring and Test Equipment 14 Handling, Storage and Shipping 15 Inspection, Test and Operating Status 16 Control of Nonconforming Items 17 Corrective Actions 18 Quality Assurance Records 19 Audits 20 TABLE 1 NQA-1 Basic Requirements Relat...

  16. Uranium Biomineralization by Natural Microbial Phosphatase Activities in the Subsurface

    Energy Technology Data Exchange (ETDEWEB)

    Sobecky, Patricia A. [Univ. of Alabama, Tuscaloosa, AL (United States)

    2015-04-06

    In this project, inter-disciplinary research activities were conducted in collaboration among investigators at The University of Alabama (UA), Georgia Institute of Technology (GT), Lawrence Berkeley National Laboratory (LBNL), Brookhaven National Laboratory (BNL), the DOE Joint Genome Institute (JGI), and the Stanford Synchrotron Radiation Light source (SSRL) to: (i) confirm that phosphatase activities of subsurface bacteria in Area 2 and 3 from the Oak Ridge Field Research Center result in solid U-phosphate precipitation in aerobic and anaerobic conditions; (ii) investigate the eventual competition between uranium biomineralization via U-phosphate precipitation and uranium bioreduction; (iii) determine subsurface microbial community structure changes of Area 2 soils following organophosphate amendments; (iv) obtain the complete genome sequences of the Rahnella sp. Y9-602 and the type-strain Rahnella aquatilis ATCC 33071 isolated from these soils; (v) determine if polyphosphate accumulation and phytate hydrolysis can be used to promote U(VI) biomineralization in subsurface sediments; (vi) characterize the effect of uranium on phytate hydrolysis by a new microorganism isolated from uranium-contaminated sediments; (vii) utilize positron-emission tomography to label and track metabolically-active bacteria in soil columns, and (viii) study the stability of the uranium phosphate mineral product. Microarray analyses and mineral precipitation characterizations were conducted in collaboration with DOE SBR-funded investigators at LBNL. Thus, microbial phosphorus metabolism has been shown to have a contributing role to uranium immobilization in the subsurface.

  17. Technical basis in support of the conversion of the University of Missouri Research Reactor (MURR) core from highly-enriched to low-enriched uranium - core neutron physics

    Energy Technology Data Exchange (ETDEWEB)

    Stillman, J. [Argonne National Lab. (ANL), Argonne, IL (United States); Feldman, E. [Univ. of Missouri, Columbia, MO (United States). Columbia Research Reactor; Foyto, L [Univ. of Missouri, Columbia, MO (United States). Columbia Research Reactor; Kutikkad, K [Univ. of Missouri, Columbia, MO (United States). Columbia Research Reactor; McKibben, J C [Univ. of Missouri, Columbia, MO (United States). Columbia Research Reactor; Peters, N. [Univ. of Missouri, Columbia, MO (United States). Columbia Research Reactor; Stevens, J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2012-09-01

    This report contains the results of reactor design and performance for conversion of the University of Missouri Research Reactor (MURR) from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL) and the MURR Facility. The core conversion to LEU is being performed with financial support of the U. S. government.

  18. Progress in studies of natural gas conversion in China

    Institute of Scientific and Technical Information of China (English)

    Yu Changchun; Shen Shikong

    2008-01-01

    Progress in natural gas conversion in China is presented in this paper, including processes of natural gas to synthesis gas (syngas), syngas to liquid hydrocarbons, oxygenates synthesis, methanol to olefins (MTO), methane to aromatics and oxidative coupling of methane (OCM).

  19. Structural characterization of mixed uranium-plutonium co-precipitates and oxides synthesized by oxalic co-conversion route

    Energy Technology Data Exchange (ETDEWEB)

    Arab-Chapelet, B.; De Bruycker, F.; Picart, S.; Leturcq, G.; Grandjean, S. [Laboratoire de Chimie des Actinides, CEA Valrho, bat 399, BP17171, 30207 Bagnols sur Ceze cedex (France)

    2008-07-01

    In this study, mixed uranium(IV)-plutonium(III) oxalate co-precipitates with Pu/(U+Pu) molar ratio equal to 29 and 45% were synthesized and characterized by X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal conversion step of these co-precipitates into oxide was carried out under argon flow up to 700 deg. C leading to mixed oxides. The structural investigation on these oxides indicates the formation of (U,Pu)O{sub 2} fluorite-type solid solution characterized by a very homogeneous distribution of plutonium and uranium, a controlled oxygen stoichiometry and well-defined morphology of particles. (authors)

  20. [Contrast study on natural radioactive nuclides contents of rice between Xiangshan uranium deposit area, Jiangxi and non-uranium depsoit area].

    Science.gov (United States)

    Liu, Ping-Hui; Ye, Chang-Sheng; Xie, Shu-Rong; Rui, Yu-Kui

    2009-07-01

    The contents of natural radioactive nuclides such as uranium and thorium in paddies were analyzed and compared by means of ICP-MS. Totally 14 paddy samples were distinguished into two groups and collected from two rice planting area. One group (12 paddy samples) was collected from the Xiangshan uranium deposit area, Jiangxi province; while the other group (2 samples) collected from non-uranium deposit suburban area of Fuzhou city, Jiangxi, as comparison samples. The distance between the two sampling areas is about 80 kilometers. Before analysis, those paddy samples were continuously carbonized by two hours first, then continuously incinerated for 8 hours at the temperature of 600 degrees centigrade. The results show that the uranium contents in the paddy ash of samples gotten from Xiangshan uranium deposit area range from 0.053 to 1.482 microg x g(-1). The uranium contents of two comparison paddy samples ash are 0.059 and 0.061 microg x g(-1), respectiovely. The average uranium content of paddy ash of uranium deposit area is 0.323 microg x g(-1). Compared with the comparison samples, the uranium contents of paddy ash of uranium deposit area are considerably high, 5.30 times that of non-uranium deposit area. The thorium contents in paddy ash of the uranium deposit area, however, are relatively low and less than that of samples collected from non-uranium deposit area, which range from 0.029 to 0.311 microg x g(-1); The average level is 0.104 microg x g(-1), only about 50% of that of paddy ash sampled from non-urnaium deposit area. Moreover, there is significant linearity correlation between uranium and thorium contents of paddy sampled from Xiangshan uranium deposit area. The positive effects show that the thorium contents of paddy increase as uranium contents of paddy in uranium deposit area increase. The causes for the remarkable difference in uranium contents in paddy between urianium deposit area and non-uranium deposit area are not clear yet. The research on

  1. Determination of natural and depleted uranium in urine at the ppt level: an interlaboratory analytical exercise

    Energy Technology Data Exchange (ETDEWEB)

    D' Agostino, P.A. [Defence R and D Canada - Suffield, Medicine Hat, Alberta (Canada); Ough, E.A. [Royal Military College of Canada, Kingston, Ontario (Canada); Glover, S.E. [Los Alamos National Lab., Los Alamos, NM (United States); Vallerand, A.L.

    2002-10-15

    An analytical exercise was initiated in order to determine those analytical procedures with the capacity to measure uranium isotope ratios ({sup 238}U/{sup 235}U) in urine samples containing less that 1{mu} uranium /L urine. A host laboratory was tasked with the preparation of six sets (12 samples per set) of synthetic urine samples spiked with varying amounts of natural and depleted (0.2% {sup 235}U) uranium. The sets of samples contained total uranium in the range 25 ng U/L urine to 770 ng U/L urine, with isotope ratios ({sup 238}U/{sup 235}U) from 137.9 (natural uranium) to 215 ({approx}50% depleted uranium). Sets of samples were shipped to five testing laboratories (four Canadian and one European) for total and isotopic assay. The techniques employed in the analyses included sector field inductively coupled plasma mass spectrometry (ICP-SF-MS), quadrupole inductively coupled plasma mass spectrometry (ICP-Q-MS), thermal ionization mass spectrometry (TIMS) and neutron activation analysis (NAA). Full results were obtained from three testing labs (ICP-SF-MS, ICP-Q-MS and TIMS). Their results, plus partial results from the NAA lab, have been included in this report. Total uranium and isotope ratio results obtained from ICP-SF-MS and ICP-Q-MS were in good agreement with the host lab values. Neutron activation analysis and TIMS reported total uranium concentrations that differed from the host lab. An incomplete set of isotopic ratios was obtained from the NAA lab with some results reporting enriched uranium (%{sup 235}U > 0.7). Based on the reported results, the four analytical procedures were ranked: ICP-SF-MS (1), ICP-Q-MS (2), TIMS (3) and NAA (4). (author)

  2. Natural uranium lattice in heavy water; Reseaux uranium naturel-eau lourde

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Y.; Koechlin, J.C.; Moreau, J.; Naudet, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-01

    all solid bars are considered and n an d the effective integrals are adjusted then a system of transposition of these results to more complex bars is sought. In the second step, one is compelled to improve the system in studying in greater detail each factor of the calculation of the lattice. A satisfactory interpretation of the results leads definitively to methods of calculation applicable to the most varied types of natural uranium-heavy water lattices. Attention has been given to results obtained in other countries, particularly in Canada. (author) [French] Un ensemble de mesures de Laplaciens a ete realise en regime critique dans une pile a eau lourde construite specialement a cette fin, soit sur reseaux complets, soit sur echantillons de reseaux par une methode a deux zones. L'appareillage experimental est brievement decrit: il a ete etudie pour permettre des modifications rapides du chargement. On decrit egalement sommairement les methodes de mesure: on opere soit par cartes de flux, sur des reseaux qui servent ensuite de reference soit par remplacement progressif des barres par couronnes concentriques et mesures de reactivite. Dans ce cas, on cherche a atteindre l'ecart entre le laplacien-matiere du reseau central inconnu et celui du reseau de reference. La methode a fait l'objet d'une mise au point destinee a la rendre precice. On donne les resultats des mesures de laplaciens pour tous ces types de reseaux, ce qui permet de construire un ensemble de courbes en fonction du pas. Divers effets ont ete egalement mesure: equivalent en reactivite du millimetre d'eau - anisotropie - effet de temperature, etc. On a cependant prefere, dans cette premiere campagne de mesures tout au moins, obtenir une grande variete de laplaciens plutot que des mesures fines dans des cas particuliers. C'est dans cet esprit qu'a ete conduite l'interpretation des resultats. Nombre de phenomenes tres complexes echappant encore a nos possibilites de

  3. Uranium redistribution under oxidizing conditions in Oklo natural reactor zone 2, Gabon

    Energy Technology Data Exchange (ETDEWEB)

    Isobe, H.; Ohnuki, T. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan); Murakami, T. [Ehime Univ., Matsuyama, Ehime (Japan); Gauthier-Lafaye, F. [CNRS, Strasbourg (France). Centre de Geochemie de la Surface

    1995-12-31

    This mineralogical study was completed to elucidate the relationships between uranium distribution and alteration products of the host rock of natural reactor zone clays just below the reactor core. Uraninite is preserved without any alteration in the reactor core. Uranium minerals are found to be present in the fractures in the reactor zone clays associated with iron-mineral veins, galena and Ti-bearing minerals. Uranium, for which the phases could not be identified, occurs in iron-mineral veins and the iron-mineral rim of pyrite grains in the reactor zone clays. Uranium is not associated with granular iron minerals occurring in the illite matrix of the reactor zone clays. The degree of crystallinity and uranium content of the three iron-bearing alteration products suggest that they formed under different conditions; the granular iron minerals, under alteration conditions where uranium was not mobilized while the iron-mineral veins and the iron-mineral rim of pyrite, under conditions in which uranium is mobilized after the formation of the granular iron minerals.

  4. Engineering assessment of inactive uranium mill tailings, Spook site, Converse County, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    1981-10-01

    Ford, Bacon and Davis Utah Inc. has reevaluated the Spook site in order to revise the December 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings 48 mi northeast of Casper, in Converse County, Wyoming. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 187,000 tons of tailings at the Spook site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite decontamination with the addition of 3 m of stabilization cover makes and gamma densitometers for measuring cross-sectionally averaged mass velocity in steady steam-water flow are presented. The results are interpreted ntation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-04-01

    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.

  6. The separation of uranium ions by natural and modified diatomite from aqueous solution.

    Science.gov (United States)

    Sprynskyy, Myroslav; Kovalchuk, Iryna; Buszewski, Bogusław

    2010-09-15

    In this work the natural and the surfactant modified diatomite has been tested for ability to remove uranium ions from aqueous solutions. Such controlling factors of the adsorption process as initial uranium concentration, pH, contact time and ionic strength have been investigated. Effect of ionic strength of solution has been examined using the solutions of NaCl, Na(2)CO(3) and K(2)SO(4). The pseudo-first order and the pseudo-second order models have been used to analyze the adsorption kinetic results, whereas the Langmuir and the Freundlich isotherms have been used to the equilibrium adsorption data. The effects of the adsorbent modification as well as uranium adsorption on the diatomite surface have been studied using X-ray powder diffraction, scanning electron microscopy and FTIR spectroscopy. The maximum adsorption capacities of the natural and the modified diatomite towards uranium were 25.63 micromol/g and 667.40 micromol/g, respectively. The desorptive solutions of HCl, NaOH, Na(2)CO(3), K(2)SO(4), CaCO(3), humic acid, cool and hot water have been tested to recover uranium from the adsorbent. The highest values of uranium desorption (86%) have been reached using 0.1M HCl. Copyright 2010 Elsevier B.V. All rights reserved.

  7. The Nature of Primary Students' Conversation in Technology Education

    Science.gov (United States)

    Fox-Turnbull, Wendy H.

    2016-01-01

    Classroom conversations are core to establishing successful learning for students. This research explores the nature of conversation in technology education in the primary classroom and the implications for teaching and learning. Over a year, two units of work in technology were taught in two primary classrooms. Most data was gathered in Round 2…

  8. Prior Experiences Shaping Family Science Conversations at a Nature Center

    Science.gov (United States)

    McClain, Lucy R.; Zimmerman, Heather Toomey

    2014-01-01

    Using families as the analytical focus, this study informs the field of informal science education with a focus on the role of prior experiences in family science conversations during nature walks at an outdoor-based nature center. Through video-based research, the team analyzed 16 families during walks at a nature center. Each family's prior…

  9. Natural uranium lattice in heavy water; Reseaux uranium naturel-eau lourde

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Y.; Koechlin, J.C.; Moreau, J.; Naudet, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-01

    all solid bars are considered and n an d the effective integrals are adjusted then a system of transposition of these results to more complex bars is sought. In the second step, one is compelled to improve the system in studying in greater detail each factor of the calculation of the lattice. A satisfactory interpretation of the results leads definitively to methods of calculation applicable to the most varied types of natural uranium-heavy water lattices. Attention has been given to results obtained in other countries, particularly in Canada. (author) [French] Un ensemble de mesures de Laplaciens a ete realise en regime critique dans une pile a eau lourde construite specialement a cette fin, soit sur reseaux complets, soit sur echantillons de reseaux par une methode a deux zones. L'appareillage experimental est brievement decrit: il a ete etudie pour permettre des modifications rapides du chargement. On decrit egalement sommairement les methodes de mesure: on opere soit par cartes de flux, sur des reseaux qui servent ensuite de reference soit par remplacement progressif des barres par couronnes concentriques et mesures de reactivite. Dans ce cas, on cherche a atteindre l'ecart entre le laplacien-matiere du reseau central inconnu et celui du reseau de reference. La methode a fait l'objet d'une mise au point destinee a la rendre precice. On donne les resultats des mesures de laplaciens pour tous ces types de reseaux, ce qui permet de construire un ensemble de courbes en fonction du pas. Divers effets ont ete egalement mesure: equivalent en reactivite du millimetre d'eau - anisotropie - effet de temperature, etc. On a cependant prefere, dans cette premiere campagne de mesures tout au moins, obtenir une grande variete de laplaciens plutot que des mesures fines dans des cas particuliers. C'est dans cet esprit qu'a ete conduite l'interpretation des resultats. Nombre de phenomenes tres complexes echappant encore a nos possibilites de

  10. Technology, Safety and Costs of Decommissioning a Reference Uranium Hexafluoride Conversion Plant

    Energy Technology Data Exchange (ETDEWEB)

    Elder, H. K.

    1981-10-01

    Safety and cost information is developed for the conceptual decommissioning of a commercial uranium hexafluoride conversion (UF{sub 6}) plant. Two basic decommissioning alternatives are studied to obtain comparisons between cost and safety impacts: DECON, and passive SAFSTOR. A third alternative, DECON of the plant and equipment with stabilization and long-term care of lagoon wastes. is also examined. DECON includes the immediate removal (following plant shutdown) of all radioactivity in excess of unrestricted release levels, with subsequent release of the site for public use. Passive SAFSTOR requires decontamination, preparation, maintenance, and surveillance for a period of time after shutdown, followed by deferred decontamination and unrestricted release. DECON with stabilization and long-term care of lagoon wastes (process wastes generated at the reference plant and stored onsite during plant operation} is also considered as a decommissioning method, although its acceptability has not yet been determined by the NRC. The decommissioning methods assumed for use in each decommissioning alternative are based on state-of-the-art technology. The elapsed time following plant shutdown required to perform the decommissioning work in each alternative is estimated to be: for DECON, 8 months; for passive SAFSTOR, 3 months to prepare the plant for safe storage and 8 months to accomplish deferred decontamination. Planning and preparation for decommissioning prior to plant shutdown is estimated to require about 6 months for either DECON or passive SAFSTOR. Planning and preparation prior to starting deferred decontamination is estimated to require an additional 6 months. OECON with lagoon waste stabilization is estimated to take 6 months for planning and about 8 months to perform the decommissioning work. Decommissioning cost, in 1981 dollars, is estimated to be $5.91 million for OECON. For passive SAFSTOR, preparing the facility for safe storage is estimated to cost $0

  11. Linearity assumption in soil-to-plant transfer factors of natural uranium and radium in Helianthus annuus L

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, P. Blanco [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Tome, F. Vera [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)]. E-mail: fvt@unex.es; Fernandez, M. Perez [Area de Ecologia, Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Lozano, J.C. [Laboratorio de Radiactividad Ambiental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain)

    2006-05-15

    The linearity assumption of the validation of soil-to-plant transfer factors of natural uranium and {sup 226}Ra was tested using Helianthus annuus L. (sunflower) grown in a hydroponic medium. Transfer of natural uranium and {sup 226}Ra was tested in both the aerial fraction of plants and in the overall seedlings (roots and shoots). The results show that the linearity assumption can be considered valid in the hydroponic growth of sunflowers for the radionuclides studied. The ability of sunflowers to translocate uranium and {sup 226}Ra was also investigated, as well as the feasibility of using sunflower plants to remove uranium and radium from contaminated water, and by extension, their potential for phytoextraction. In this sense, the removal percentages obtained for natural uranium and {sup 226}Ra were 24% and 42%, respectively. Practically all the uranium is accumulated in the roots. However, 86% of the {sup 226}Ra activity concentration in roots was translocated to the aerial part.

  12. Evaluation of the Acceptability of Potential Depleted Uranium Hexafluoride Conversion Products at the Envirocare Disposal Site

    Energy Technology Data Exchange (ETDEWEB)

    Croff, A.G.

    2001-01-11

    The purpose of this report is to review and document the capability of potential products of depleted UF{sub 6} conversion to meet the current waste acceptance criteria and other regulatory requirements for disposal at the facility in Clive, Utah, owned by Envirocare of Utah, Inc. The investigation was conducted by identifying issues potentially related to disposal of depleted uranium (DU) products at Envirocare and conducting an initial analysis of them. Discussions were then held with representatives of Envirocare, the state of Utah (which is a NRC Agreement State and, thus, is the cognizant regulatory authority for Envirocare), and DOE Oak Ridge Operations. Provisional issue resolution was then established based on the analysis and discussions and documented in a draft report. The draft report was then reviewed by those providing information and revisions were made, which resulted in this document. Issues that were examined for resolution were (1) license receipt limits for U isotopes; (2) DU product classification as Class A waste; (3) use of non-DOE disposal sites for disposal of DOE material; (4) historical NRC views; (5) definition of chemical reactivity; (6) presence of mobile radionuclides; and (7) National Environmental Policy Act coverage of disposal. The conclusion of this analysis is that an amendment to the Envirocare license issued on October 5, 2000, has reduced the uncertainties regarding disposal of the DU product at Envirocare to the point that they are now comparable with uncertainties associated with the disposal of the DU product at the Nevada Test Site that were discussed in an earlier report.

  13. Conversion of uranium nuclear fuel into U 3O 8 at the head end of HTR reprocessing

    Science.gov (United States)

    Hoogen, N.; Aschhoff, H. G.; Staib, G.

    1984-04-01

    Corresponding to the reference procedure for the head-end treatment of HTR fuel elements, separation of the moderator graphite from the materials uranium and plutonium is envisaged by combustion in the fluidized bed. Due to the defective silicon carbide layers of the uranium fuel particles a chemical conversion of the UO 2 kernel into U 3O 8 takes place in the oxidizing atmosphere of the combustion process. This reaction proceeds spontaneously and quantitatively, and causes a disintegration of the heavy metal kernel. It is observed that the degree of hardness of the kernel fragments is clearly dependent on the heat-up rate. In the commercial design of the head-end process step, attention must be paid to the cross-over of fuel from the stationary fluidized bed into the dust discharge.

  14. Efficient introduction of natural uranium and thorium into nuclear energy system

    Energy Technology Data Exchange (ETDEWEB)

    Blandinskiy, Victor [National Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)

    2016-09-15

    This article describes differences between two approaches of understanding the main goal of nuclear energy system: effective plutonium consumption versus effective natural uranium and thorium consumption. Several options of sodium cooled fast reactor are considered to provide increased breeding and thorium involving into nuclear energy system.

  15. EXPOSURE LEVELS FOR PERSONNEL OF NON-URANIUM UNDERGROUND ENTERPRISES FROM NATURAL IRRADIATION SOURCES

    Directory of Open Access Journals (Sweden)

    N. A. Koroljova

    2008-01-01

    Full Text Available The article contains the analysis of the results of radiation survey at more than 100 non-uranium mining enterprises fulfilled by the Institute over the last 20 years. The article considers radiation situation formation appropriateness, demonstrates the evaluation of effective exposure doses of mining enterprises personnel from natural irradiation sources in working conditions, the dose structure is given.

  16. AMS of natural 236U and 239Pu produced in uranium ores

    Science.gov (United States)

    Wilcken, K. M.; Barrows, T. T.; Fifield, L. K.; Tims, S. G.; Steier, P.

    2007-06-01

    The rare isotopes 236U and 239Pu are produced naturally by neutron capture in uranium ores. Here we measure 236U and 239Pu by accelerator mass spectrometry (AMS) in the same ore samples for the first time. To ensure efficient extraction of both elements and isotopic equilibrium between the 239Pu in the ore and a 242Pu spike, we developed a new sample preparation protocol. AMS has clear advantages over previous methods because it achieves better discrimination against molecular interferences with higher sensitivity and shorter counting times. Measurements of 236U and 239Pu hold considerable promise as proxy indicators of neutron flux and uranium concentration.

  17. Method of quantitatively separating uranium from specimens of natural water by sorption on silica

    Energy Technology Data Exchange (ETDEWEB)

    Putral, A.; Schwochau, K.

    1981-08-11

    A method of quantitatively separating uranium from specimens of natural water, especially sea water or from solutions which as to their composition are comparable to such specimens, while silica gel is provided for adsorbing the uranium. The liquid of the specimens or solution is conveyed over granular silica gel having an average grain diameter not exceeding 0.5 mm. The through-flow speed is so selected that the contact time period for the liquid with the silica gel amounts to at least 50 seconds, whereupon the uranium adsorbed on the silica gel is separated therefrom by elutriation with at least 0.1 normal oxidizing mineral acid. The volume of the elutriate utilized, should amount to at least twice the volume of the silica gel, and this proportion of the elutriate should, if possible, not be exceeded.

  18. Uranium Biomineralization by Natural Microbial Phosphatase Activities in the Subsurface

    Science.gov (United States)

    Martinez, R.; Wu, C. H.; Beazley, M. J.; Andersen, G. L.; Hazen, T. C.; Taillefert, M.; Sobecky, P. A.

    2011-12-01

    Soils and groundwater contaminated with heavy metals and radionuclides remain a legacy of Cold War nuclear weapons development. Due to the scale of environmental contamination, in situ sequestration of heavy metals and radionuclides remain the most cost-effective strategy for remediation. We are currently investigating a remediation approach that utilizes periplasmic and extracellular microbial phosphatase activity of soil bacteria capable promoting in situ uranium phosphate sequestration. Our studies focus on the contaminated soils from the DOE Field Research Center (ORFRC) in Oak Ridge, TN. We have previously demonstrated that ORFRC strains with phosphatase-positive phenotypes were capable of promoting the precpitation of >95% U(VI) as a low solubility phosphate mineral during growth on glycerol phosphate as a sole carbon and phosphorus source. Here we present culture-independent soil slurry studies aimed at understanding microbial community dynamics resulting from exogenous organophosphate additions. Soil slurries containing glycerol-2-phosphate (G2P) or glycerol-3-phosphate (G3P) and nitrate as the sole C, P and N sources were incubated under oxic growth conditions at pH 5.5 or pH 6.8. Following treatments, total DNA was extracted and prokaryotic diversity was assessed using high-density 16S oligonucleotide microarray (PhyloChip) analysis. Treatments at pH 5.5 and pH 6.8 amended with G2P required 36 days to accumulate 4.8mM and 2.2 mM phosphate, respectively. In contrast, treatments at pH 5.5 and pH 6.8 amended with G3P accumulated 8.9 mM and 8.7 mM phosphate, respectively, after 20 days. A total of 2120 unique taxa representing 46 phyla, 66 classes, 110 orders, and 186 families were detected among all treatment conditions. The phyla that significantly (P<0.05) increased in abundance relative to incubations lacking organophosphate amendments included: Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria. Members from the classes Bacteroidetes

  19. Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    GAN Huajun; XIAO Xianming; LU Yongchao; JIN Yongbin; TIAN Hui; LIU Dehan

    2007-01-01

    The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbonbearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium (U)and Total Organic Carbon (TOC) of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.

  20. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    Energy Technology Data Exchange (ETDEWEB)

    Ovaskainen, R

    1999-11-01

    The mass spectrometric determination of minor abundant isotopes, {sup 234}U and {sup 236}U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n({sup 234}U)/n({sup 238}U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n({sup 234}U)/n({sup 235}U) and n({sup 236}U)/n({sup 235}U) ratios were determined using ion counting in combination with the decelerating device. The n({sup 235}U)/n({sup 238}U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n({sup 234}U)/n({sup 235}U) ratios and 5-25 percent for the n({sup 236}U)/n({sup 235}U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International

  1. Technology, Safety and Costs of Decommissioning a Reference Uranium Hexafluoride Conversion Plant

    Energy Technology Data Exchange (ETDEWEB)

    Elder, H. K.

    1981-10-01

    Safety and cost information is developed for the conceptual decommissioning of a commercial uranium hexafluoride conversion (UF{sub 6}) plant. Two basic decommissioning alternatives are studied to obtain comparisons between cost and safety impacts: DECON, and passive SAFSTOR. A third alternative, DECON of the plant and equipment with stabilization and long-term care of lagoon wastes. is also examined. DECON includes the immediate removal (following plant shutdown) of all radioactivity in excess of unrestricted release levels, with subsequent release of the site for public use. Passive SAFSTOR requires decontamination, preparation, maintenance, and surveillance for a period of time after shutdown, followed by deferred decontamination and unrestricted release. DECON with stabilization and long-term care of lagoon wastes (process wastes generated at the reference plant and stored onsite during plant operation} is also considered as a decommissioning method, although its acceptability has not yet been determined by the NRC. The decommissioning methods assumed for use in each decommissioning alternative are based on state-of-the-art technology. The elapsed time following plant shutdown required to perform the decommissioning work in each alternative is estimated to be: for DECON, 8 months; for passive SAFSTOR, 3 months to prepare the plant for safe storage and 8 months to accomplish deferred decontamination. Planning and preparation for decommissioning prior to plant shutdown is estimated to require about 6 months for either DECON or passive SAFSTOR. Planning and preparation prior to starting deferred decontamination is estimated to require an additional 6 months. OECON with lagoon waste stabilization is estimated to take 6 months for planning and about 8 months to perform the decommissioning work. Decommissioning cost, in 1981 dollars, is estimated to be $5.91 million for OECON. For passive SAFSTOR, preparing the facility for safe storage is estimated to cost $0

  2. Study on Evaluation of Project Management Data for Decommissioning of Uranium Refining and Conversion Plant - 12234

    Energy Technology Data Exchange (ETDEWEB)

    Usui, Hideo; Izumo, Sari; Tachibana, Mitsuo [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki, 319-1195 (Japan); Shibahara, Yuji [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki, 319-1195 (Japan); University of Fukui, Fukui-shi, Fukui, 910-8507 (Japan); Morimoto, Yasuyuki; Tokuyasu, Takashi; Takahashi, Nobuo; Tanaka, Yoshio; Sugitsue, Noritake [Japan Atomic Energy Agency, Kagamino-cho, Tomata-gun, Okayama, 708-0698 (Japan)

    2012-07-01

    Some of nuclear facilities that would no longer be required have been decommissioned in JAEA (Japan Atomic Energy Agency). A lot of nuclear facilities have to be decommissioned in JAEA in near future. To implement decommissioning of nuclear facilities, it was important to make a rational decommissioning plan. Therefore, project management data evaluation system for dismantling activities (PRODIA code) has been developed, and will be useful for making a detailed decommissioning plan for an object facility. Dismantling of dry conversion facility in the uranium refining and conversion plant (URCP) at Ningyo-toge began in 2008. During dismantling activities, project management data such as manpower and amount of waste generation have been collected. Such collected project management data has been evaluated and used to establish a calculation formula to calculate manpower for dismantling equipment of chemical process and calculate manpower for using a green house (GH) which was a temporary structure for preventing the spread of contaminants during dismantling. In the calculation formula to calculate project management data related to dismantling of equipment, the relation of dismantling manpower to each piece of equipment was evaluated. Furthermore, the relation of dismantling manpower to each chemical process was evaluated. The results showed promise for evaluating dismantling manpower with respect to each chemical process. In the calculation formula to calculate project management data related to use of the GH, relations of GH installation manpower and removal manpower to GH footprint were evaluated. Furthermore, the calculation formula for secondary waste generation was established. In this study, project management data related to dismantling of equipment and use of the GH were evaluated and analyzed. The project management data, manpower for dismantling of equipment, manpower for installation and removal of GH, and secondary waste generation from GH were considered

  3. The catalytic conversion of natural gas to useful products

    NARCIS (Netherlands)

    Ross, J.R.H.; Ross, J.R.H.; van Keulen, A.N.J.; van Keulen, A.N.J.; Hegarty, M.E.S.; Seshan, Kulathuiyer

    1996-01-01

    This paper gives a brief summary of some processes, direct and indirect, for the conversion of natural gas to useful products. It then proceeds to give an outline of some work from the authors' laboratories on subjects such as steam reforming, oxidative coupling and CO2 reforming of methane, paying

  4. Learning by Communicating in Natural Language with Conversational Agents

    Science.gov (United States)

    Graesser, Arthur; Li, Haiying; Forsyth, Carol

    2014-01-01

    Learning is facilitated by conversational interactions both with human tutors and with computer agents that simulate human tutoring and ideal pedagogical strategies. In this article, we describe some intelligent tutoring systems (e.g., AutoTutor) in which agents interact with students in natural language while being sensitive to their cognitive…

  5. An efficiency booster for energy conversion in natural circulation loops

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dongqing, E-mail: wangdongqing@stu.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Beijing Computational Science Research Center, Beijing 100084 (China); Jiang, Jin, E-mail: jjiang@eng.uwo.ca [Department of Electrical and Computer Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Beijing Computational Science Research Center, Beijing 100084 (China)

    2016-08-01

    Highlights: • Low driving power conversion efficiency of natural circulation loops is proved. • The low conversion efficiency leads to low heat transfer capacity of such loops. • An efficiency booster is designed with turbine to increase the efficiency. • Performance of the proposed booster has been numerically simulated. • The booster drastically enhances heat transfer capacity of such loops. - Abstract: In this paper, the capacity of a natural circulation loop for transferring heat from a heat source to a heat sink has been analyzed. It is concluded that the capacity of the natural circulation loop depends on the conversion efficiency of the thermal energy from the heat source to the driving force for the circulation of the flow. The low conversion efficiency leading to weak driving force in such loops has been demonstrated analytically and validated through simulation results. This issue has resulted in a low heat transfer capacity in the circulation loop. To increase the heat transfer capacity, one has to improve this efficiency. To meet such a need, a novel efficiency booster has been developed in this paper. The booster essentially increases the flow driving force and hence significantly improves the overall heat transfer capacity. Design and analysis of this booster have been performed in detail. The performance has been examined through extensive computer simulations. It is concluded that the booster can indeed drastically improve the heat transfer capacity of the natural circulation loop.

  6. Assessment of contamination of the Issyk-Kul' valley natural waters with uranium mine wastes

    Energy Technology Data Exchange (ETDEWEB)

    Palesski, S.V.; Nikolaeva, I.V.; Saprykin, A.I.; Gavshin, V.M. [The United Institute of Geology, Geophysics and Mineralogy SB RAS, Novosibirsk (Russian Federation)

    2003-05-01

    The Lake Issyk-Kul' of the central Tyan-Shan is characterized by increased natural uranium content. Uranium-carbon deposit situated on the southern bank of the Lake can be the reason of chemical and radioactive contamination of this unique basin by exploitation wastes. In order to estimate possible danger, a project 'Assessment and prognosis of environmental changes in Lake Issyk-Kul' (Kyrgyzstan)' was developed and supported by the Program of the European Commission 'Copernicus-2' (2001-2003). According to this project the water assays were sampled from different depths near the banks of the Lake and from low-debit sources draining the dumping grounds of the uranium-carbon deposit. Elemental and isotopic examinations of these water samples were performed using an ELEMENT HR-ICP-MS (Finnigan Mat). The results obtained are the evidence that the ecological status of the Lake Issyk-Kul'is not damaged at present. Wastewaters from the uranium-carbon mine do not make decisive contribution into the natural radioactive background. (authors)

  7. Assessment of natural radioactivity in aquifer medium bearing uranium ores in Koprubasi, Turkey

    Science.gov (United States)

    Simsek, Celalettin

    2008-10-01

    Koprubasi, located within Manisa Province near the Izmir, is the biggest uranium mine where uranium ores originate from Neogene aged altered sandstone and conglomerate layers. The main objective of this study is to determine the radiation hazard associated with radioactivity levels of uranium ores, and the rocks and sediments around Koprubasi. In this regard, measured activity levels of 226Ra, 232Th and 40K were compared with world averages. The average activity levels of 226 Ra, 232Th and 40K were measured to be 5369.75, 124.78 and 10.0 Bq/kg in uranium ores, 24.32, 52.94 and 623.38 Bq/kg in gneiss, 46.24, 45.13 and 762.26 Bq/kg in sandstone and conglomerate, 73.11, 43.15 and 810.65 Bq/kg in sediments, respectively. All samples have high 226Ra and 40K levels according to world average level. As these sediments are used as construction materials and in agricultural activities within the study area, the radiation hazard are calculated by using dose rate (D), annual effective dose rate (He), radium equivalent activity (Raeq) and radiation hazard index (Iyr). All the samples have Raeq levels that are lower than the world average limit of 370 Bq/kg. On the other hand, D, He and Iyr values are higher than world average values. These results indicate that the uranium ores in the Koprubasi is the most important contributor to the natural radiation level. The radioactivity levels of sediments and rocks make them unsuitable for use as agricultural soil and as construction materials. Moreover, it is determined that shallow groundwater in sediments and deep groundwater in conglomerate rocks and also surface water sources in the Koprubasi have high 226Ra content. According to environmental radioactive baseline, some environmental protection study must be taken in Koprubasi uranium site and the environment.

  8. Preliminary Accident Analyses for Conversion of the Massachusetts Institute of Technology Reactor (MITR) from Highly Enriched to Low Enriched Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Floyd E. [Argonne National Lab. (ANL), Argonne, IL (United States); Olson, Arne P. [Argonne National Lab. (ANL), Argonne, IL (United States); Wilson, Erik H. [Argonne National Lab. (ANL), Argonne, IL (United States); Sun, Kaichao S. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Newton, Jr., Thomas H. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Hu, Lin-wen [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-09-30

    The Massachusetts Institute of Technology Reactor (MITR-II) is a research reactor in Cambridge, Massachusetts designed primarily for experiments using neutron beam and in-core irradiation facilities. It delivers a neutron flux comparable to current LWR power reactors in a compact 6 MW core using Highly Enriched Uranium (HEU) fuel. In the framework of its non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context most research and test reactors, both domestic and international, have started a program of conversion to the use of LEU fuel. A new type of LEU fuel based on an alloy of uranium and molybdenum (U-Mo) is expected to allow the conversion of U.S. domestic high performance reactors like MITR. This report presents the preliminary accident analyses for MITR cores fueled with LEU monolithic U-Mo alloy fuel with 10 wt% Mo. Preliminary results demonstrate adequate performance, including thermal margin to expected safety limits, for the LEU accident scenarios analyzed.

  9. STUDY FOR NATURAL GAS HYDRATE CONVERSED FROM ICE

    Institute of Scientific and Technical Information of China (English)

    WANG Shengjie; SHEN Jiandong; HAO Miaoli; LIU Furong

    2003-01-01

    Natural gas hydrates are crystalline clathrate compounds composed of water and gases of small molecular diameters that can be used for storage and transport of natural gas as a novel method. In the paper a series of experiments of aspects and kinetics for hydrate formed from natural gas and ice were carried out on the industrial small scale production apparatus. The experimental results show that formation conditions of hydrate conversed from ice are independent of induction time, and bigger degrees of supersaturation and supercooling improved the driving force and advanced the hydrate formation.Superpressure is also favorable for ice particle conversion to hydrate. In addition, it was found there have an optimal reaction time during hydrate formation.

  10. Accident Analyses for Conversion of the University of Missouri Research Reactor (MURR) from Highly-Enriched to Low-Enriched Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Stillman, J. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Div., Research and Test Reactor Dept.; Feldman, E. E. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Div., Research and Test Reactor Dept.; Wilson, E. H. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Div., Research and Test Reactor Dept.; Foyto, L. P. [Univ. of Missouri, Columbia, MO (United States). Research Reactor; Kutikkad, K. [Univ. of Missouri, Columbia, MO (United States). Research Reactor; McKibben, J. C. [Univ. of Missouri, Columbia, MO (United States). Research Reactor; Peters, N. J. [Univ. of Missouri, Columbia, MO (United States). Research Reactor; Cowherd, W. M. [Univ. of Missouri, Columbia, MO (United States). College of Engineering, Nuclear Engineering Program; Rickman, B. [Univ. of Missouri, Columbia, MO (United States). College of Engineering, Nuclear Engineering Program

    2014-12-01

    This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL), the MURR Facility, and the Nuclear Engineering Program – College of Engineering, University of Missouri-Columbia. The core conversion to LEU is being performed with financial support from the U. S. government. This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL), the MURR Facility, and the Nuclear Engineering Program – College of Engineering, University of Missouri-Columbia. The core conversion to LEU is being performed with financial support from the U. S. government. In the framework of non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context most research and test reactors, both domestic and international, have started a program of conversion to the use of LEU fuel. A new type of LEU fuel based on an alloy of uranium and molybdenum (U-Mo) is expected to allow the conversion of U.S. domestic high performance reactors like MURR. This report presents the results of a study of core behavior under a set of accident conditions for MURR cores fueled with HEU U-Alx dispersion fuel or LEU monolithic U-Mo alloy fuel with 10 wt% Mo

  11. Feasibility study on AFR-100 fuel conversion from uranium-based fuel to thorium-based fuel

    Energy Technology Data Exchange (ETDEWEB)

    Heidet, F.; Kim, T.; Grandy, C. (Nuclear Engineering Division)

    2012-07-30

    Although thorium has long been considered as an alternative to uranium-based fuels, most of the reactors built to-date have been fueled with uranium-based fuel with the exception of a few reactors. The decision to use uranium-based fuels was initially made based on the technology maturity compared to thorium-based fuels. As a result of this experience, lot of knowledge and data have been accumulated for uranium-based fuels that made it the predominant nuclear fuel type for extant nuclear power. However, following the recent concerns about the extent and availability of uranium resources, thorium-based fuels have regained significant interest worldwide. Thorium is more abundant than uranium and can be readily exploited in many countries and thus is now seen as a possible alternative. As thorium-based fuel technologies mature, fuel conversion from uranium to thorium is expected to become a major interest in both thermal and fast reactors. In this study the feasibility of fuel conversion in a fast reactor is assessed and several possible approaches are proposed. The analyses are performed using the Advanced Fast Reactor (AFR-100) design, a fast reactor core concept recently developed by ANL. The AFR-100 is a small 100 MW{sub e} reactor developed under the US-DOE program relying on innovative fast reactor technologies and advanced structural and cladding materials. It was designed to be inherently safe and offers sufficient margins with respect to the fuel melting temperature and the fuel-cladding eutectic temperature when using U-10Zr binary metal fuel. Thorium-based metal fuel was preferred to other thorium fuel forms because of its higher heavy metal density and it does not need to be alloyed with zirconium to reduce its radiation swelling. The various approaches explored cover the use of pure thorium fuel as well as the use of thorium mixed with transuranics (TRU). Sensitivity studies were performed for the different scenarios envisioned in order to determine the

  12. Natural radioactivity, dose assessment and uranium uptake by agricultural crops at Khan Al-Zabeeb, Jordan

    Energy Technology Data Exchange (ETDEWEB)

    Al-Kharouf, Samer J. [Royal Scientific Society, Amman 11941 (Jordan); Al-Hamarneh, Ibrahim F. [Prince Abdullah Bin Ghazi Faculty of Science and IT, Al-Balqa Applied University (BAU), Salt 19117 (Jordan)], E-mail: hamarnehibrahim@yahoo.com; Dababneh, Munir [Prince Abdullah Bin Ghazi Faculty of Science and IT, Al-Balqa Applied University (BAU), Salt 19117 (Jordan)

    2008-07-15

    Khan Al-Zabeeb, an irrigated cultivated area lies above a superficial uranium deposits, is regularly used to produce vegetables and fruits consumed by the public. Both soil and plant samples collected from the study area were investigated for their natural radioactivity to determine the uranium uptake by crops and hence to estimate the effective dose equivalent to human consumption. Concentrations of {sup 238}U, {sup 235}U, {sup 232}Th, {sup 226}Ra, {sup 222}Rn, {sup 137}Cs and {sup 40}K in nine soil profiles were measured by gamma-ray spectrometry whereas watermelon and zucchini crops were analyzed for their uranium content by means of alpha spectrometry after radiochemical separation. Correlations between measured radionuclides were made and their activity ratios were determined to evaluate their geochemical behavior in the soil profiles. Calculated soil-plant transfer factors indicate that the green parts (leaves, stems and roots) of the studied crops tend to accumulate uranium about two orders of magnitude higher than the fruits. The maximum dose from ingestion of 1 kg of watermelon pulp was estimated to be 3.1 and 4.7 nSv y{sup -1} for {sup 238}U and {sup 234}U, respectively. Estimations of the annual effective dose equivalent due to external exposure showed extremely low values. Radium equivalent activity and external hazard index were seen to exceed the permissible limits of 370 Bq kg{sup -1} and 1, respectively.

  13. Reuse of ammonium fluoride generated in the uranium hexafluoride conversion; Reutilizacao do fluoreto de amonio gerado na reconversao do hexafluoreto de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Silva Neto, J.B.; Carvalho, E.F. Urano de; Durazzo, M., E-mail: jbsneto@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Riella, H.G [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2010-07-01

    The Nuclear Fuel Centre of IPEN / CNEN - SP develops and manufactures dispersion fuel with high uranium concentration to meet the demand of the IEA-R1 reactor and future research reactors planned to be constructed in Brazil. The fuel uses uranium silicide (U{sub 3}Si{sub 2}) dispersed in aluminum. For producing the fuel, the processes for uranium hexafluoride (UF{sub 6}) conversion consist in obtaining U{sub 3}Si{sub 2} and / or U{sub 3}O{sub 8} through the preparation of intermediate compounds, among them ammonium uranyl carbonate - AUC, ammonium diuranate - DUA and uranium tetrafluoride - UF{sub 4}. This work describes a procedure for preparing uranium tetrafluoride by a dry route using as raw material the filtrate generated when producing routinely ammonium uranyl carbonate. The filtrate consists primarily of a solution containing high concentrations of ammonium (NH{sub 4}{sup +}), fluoride (F{sup -}), carbonate (CO{sub 3}{sup --}) and low concentrations of uranium. The procedure is basically the recovery of NH{sub 4}F and uranium, as UF{sub 4}, through the crystallization of ammonium bifluoride (NH{sub 4}HF{sub 2}) and, in a later step, the addition of UO{sub 2}, occurring fluoridation and decomposition. The UF{sub 4} obtained is further diluted in the UF{sub 4} produced routinely at IPEN / CNEN-SP by a wet route process. (author)

  14. Uranium hexafluoride handling. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    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.

  15. AMS of natural {sup 236}U and {sup 239}Pu produced in uranium ores

    Energy Technology Data Exchange (ETDEWEB)

    Wilcken, K.M. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia)]. E-mail: k.wilcken@suerc.gla.ac.uk; Barrows, T.T. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia); Fifield, L.K. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia); Tims, S.G. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia); Steier, P. [VERA Laboratory, Institute for Isotopic Research and Nuclear Physics, University of Vienna, Waehringer Strasse 17, A-1090 Vienna (Austria)

    2007-06-15

    The rare isotopes {sup 236}U and {sup 239}Pu are produced naturally by neutron capture in uranium ores. Here we measure {sup 236}U and {sup 239}Pu by accelerator mass spectrometry (AMS) in the same ore samples for the first time. To ensure efficient extraction of both elements and isotopic equilibrium between the {sup 239}Pu in the ore and a {sup 242}Pu spike, we developed a new sample preparation protocol. AMS has clear advantages over previous methods because it achieves better discrimination against molecular interferences with higher sensitivity and shorter counting times. Measurements of {sup 236}U and {sup 239}Pu hold considerable promise as proxy indicators of neutron flux and uranium concentration.

  16. Fuel handling accident analysis for the University of Missouri Research Reactor's High Enriched Uranium to Low Enriched Uranium fuel conversion initiative

    Science.gov (United States)

    Rickman, Benjamin

    In accordance with the 1986 amendment concerning licenses for research and test reactors, the MU Research Reactor (MURR) is planning to convert from using High-Enriched Uranium (HEU) fuel to the use of Low-Enriched Uranium (LEU) fuel. Since the approval of a new LEU fuel that could meet the MURR's performance demands, the next phase of action for the fuel conversion process is to create a new Safety Analysis Report (SAR) with respect to the LEU fuel. A component of the SAR includes the Maximum Hypothetical Accident (MHA) and accidents that qualify under the class of Fuel Handling Accidents (FHA). In this work, the dose to occupational staff at the MURR is calculated for the FHAs. The radionuclide inventory for the proposed LEU fuel was calculated using the ORIGEN2 point-depletion code linked to the MURR neutron spectrum. The MURR spectrum was generated from a Monte Carlo Neutron transPort (MCNP) simulation. The coupling of these codes create MONTEBURNS, a time-dependent burnup code. The release fraction from each FHA within this analysis was established by the methodology of the 2006 HEU SAR, which was accepted by the NRC. The actual dose methodology was not recorded in the HEU SAR, so a conservative path was chosen. In compliance to NUREG 1537, when new methodology is used in a HEU to LEU analysis, it is necessary to re-evaluate the HEU accident. The Total Effective Dose Equivalent (TEDE) values were calculated in addition to the whole body dose and thyroid dose to operation personnel. The LEU FHA occupational TEDE dose was 349 mrem which is under the NRC regulatory occupational dose limit of 5 rem TEDE, and under the LEU MHA limit of 403 mrem. The re-evaluated HEU FHA occupational TEDE dose was 235 mrem, which is above the HEU MHA TEDE dose of 132 mrem. Since the new methodology produces a dose that is larger than the HEU MHA, we can safely assume that it is more conservative than the previous, unspecified dose.

  17. Separation of protactinium in the reaction of 60 MeV/nucleon 18O ions with natural uranium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The activities of protactinium were produced by the multi-nucleontransfer reactions in bombardment of the natural uranium with 60 MeV/nucleon 1sOions. A simple, relatively fast radiochemical procedure was used for extraction sep-aration of protactinium from the uranium and a variety of reaction products using1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and tri-iso-octylamine as extractants. Theγ ray spectrum of the separated protactinium fractions showed that the protactiniumcould be separated from all of the main impurity elements. The decontaminationfactors of the uranium and the main reaction products produced in the reaction aregiven.``

  18. Inferring Social Nature of Conversations from Words: Experiments on a Corpus of Everyday Telephone Conversations

    Science.gov (United States)

    Stark, Anthony; Kaye, Jeffrey

    2013-01-01

    Language is being increasingly harnessed to not only create natural human-machine interfaces but also to infer social behaviors and interactions. In the same vein, we investigate a novel spoken language task, of inferring social relationships in two-party conversations: whether the two parties are related as family, strangers or are involved in business transactions. For our study, we created a corpus of all incoming and outgoing calls from a few homes over the span of a year. On this unique naturalistic corpus of everyday telephone conversations, which is unlike Switchboard or any other public domain corpora, we demonstrate that standard natural language processing techniques can achieve accuracies of about 88%, 82%, 74% and 80% in differentiating business from personal calls, family from non-family calls, familiar from unfamiliar calls and family from other personal calls respectively. Through a series of experiments with our classifiers, we characterize the properties of telephone conversations and find: (a) that 30 words of openings (beginnings) are sufficient to predict business from personal calls, which could potentially be exploited in designing context sensitive interfaces in smart phones; (b) our corpus-based analysis does not support Schegloff and Sack’s manual analysis of exemplars in which they conclude that pre-closings differ significantly between business and personal calls – closing fared no better than a random segment; and (c) the distribution of different types of calls are stable over durations as short as 1–2 months. In summary, our results show that social relationships can be inferred automatically in two-party conversations with sufficient accuracy to support practical applications. PMID:24187435

  19. Preliminary Study of Lead-Oxide Cooled Fast Reactor with Natural Uranium as an Input Fuel with Reactor Shuffling Strategy

    Science.gov (United States)

    Mahmudah, Rida SN; Su’ud, Zaki

    2017-01-01

    A preliminary study of lead-oxide cooled fast reactor with natural uranium as an input fuel using reactor shuffling strategy has been conducted. In this study, reactor core is divided into four zone with the same volume, each zone use different uranium enrichment. The enrichment number is estimated so that in the end of reactor’s operation, we only need to add natural uranium as the fresh input fuel. This study used UN-PuN as the fuel and lead oxide as the coolant. Several parameter studies have been conducted to determine the most suitable input condition. It is confirmed in this study that with fuel : cladding : coolant ratio of 53 : 10 : 37, and uranium enrichment in the first to the fourth zone of 0%, 6.25%, 7.5% and 8%, respectively, the reactor can operate as long as 20 years of operation with terminal k-eff of 1.0004.

  20. Doses and risks from uranium are not increased significantly by interactions with natural background photon radiation.

    Science.gov (United States)

    Tanner, R J; Eakins, J S; Jansen, J T M; Harrison, J D

    2012-08-01

    The impact of depleted uranium (DU) on human health has been the subject of much conjecture. Both the chemical and radiological aspects of its behaviour in the human body have previously been investigated in detail, with the radiological impact being assumed to be linked to the alpha decay of uranium. More recently, it has been proposed that the accumulation in tissue of high-Z materials, such as DU, may give rise to enhanced local energy deposition in the presence of natural background photon radiation due to the high photoelectric interaction cross sections of high-Z atoms. It is speculated that, in addition to producing short-range photoelectrons, these events will be followed by intense Auger and Coster-Kronig electron emission, thereby causing levels of cell damage that are unaccounted for in conventional models of radiological risk. In this study, the physical and biological bases of these claims are investigated. The potential magnitudes of any effect are evaluated and discussed, and compared with the risks from other radiological or chemical hazards. Monte Carlo calculations are performed to estimate likely energy depositions due to the presence of uranium in human tissues in photon fields: whole body doses, organ doses in anthropomorphic phantoms and nano-/micro-dosimetric scenarios are each considered. The proposal is shown generally to be based on sound physics, but overall the impact on human health is expected to be negligible.

  1. Evidence of isotopic fractionation of natural uranium in cultured human cells

    Science.gov (United States)

    Paredes, Eduardo; Avazeri, Emilie; Malard, Véronique; Vidaud, Claude; Reiller, Pascal E.; Ortega, Richard; Nonell, Anthony; Isnard, Hélène; Chartier, Frédéric; Bresson, Carole

    2016-12-01

    The study of the isotopic fractionation of endogen elements and toxic heavy metals in living organisms for biomedical applications, and for metabolic and toxicological studies, is a cutting-edge research topic. This paper shows that human neuroblastoma cells incorporated small amounts of uranium (U) after exposure to 10 µM natural U, with preferential uptake of the 235U isotope with regard to 238U. Efforts were made to develop and then validate a procedure for highly accurate n(238U)/n(235U) determinations in microsamples of cells. We found that intracellular U is enriched in 235U by 0.38 ± 0.13‰ (2σ, n = 7) relative to the exposure solutions. These in vitro experiments provide clues for the identification of biological processes responsible for uranium isotopic fractionation and link them to potential U incorporation pathways into neuronal cells. Suggested incorporation processes are a kinetically controlled process, such as facilitated transmembrane diffusion, and the uptake through a high-affinity uranium transport protein involving the modification of the uranyl (UO22+) coordination sphere. These findings open perspectives on the use of isotopic fractionation of metals in cellular models, offering a probe to track uptake/transport pathways and to help decipher associated cellular metabolic processes.

  2. Conversion of diesel engines for natural gas engines; Conversao de motores diesel para gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Mauro Junior, Leonardo; Almeida, Silvio Carlos Anibal de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)], e-mail: leonardomauro@terra.com.br, e-mail: silvio@gmail.com

    2006-07-01

    The present project approach the conversion of a Scania engine DSI 11, originally Diesel cycle, used for stationary generation, to operate at a Otto cycle natural gas. The conversion dedicated to Otto cycle allows a better performance at a lower cost generation to the consumer providing an energy economy when operating at a peak hours compared with the fees charged by the distributors. In the power range of this engine (231 kw), there is no other engine available at the brazilian market. An economic study of the conversion shows that the cost is significantly less than the importation of a similar engine. (author)

  3. Linking AS, SE, V, and MN Behavior to Natural Biostimulated Uranium Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Keimowitz, Alison [Vassar College, Poughkeepsie, NY (United States); Ranville, James [Colorado School of Mines, Golden, CO (United States); Mailloux, Brian [Barnard College, New York, NY (United States); Figueroa, Linda [Colorado School of Mines, Golden, CO (United States)

    2016-03-16

    The project “Linking As, Se, V, and Mn behavior to Natural and Biostimulated Uranium Cycling” successfully investigated Arsenic cycling the Rifle Colorado IFRC. This project trained undergraduate and graduate students at the Colorado School of Mines, Vassar College, and Barnard College. This resulted in both undergraduate theses and a PhD thesis and multiple publications. The science was highly successful and we were able to test the main hypotheses. We have shown that (H1) under reducing conditions that promote uranium immobilization arsenic is readily mobilized, that (H2) thioarsenic species are abundant during this mobilization, and (H3) we have examined arsenic mobilization for site sediment. At the Rifle IFRC Acetate was added during experiments to immobilize Uranium. These experiments successfully immobilized uranium but unfortunately would mobilize arsenic. We developed robust sampling and analysis methods for thioarsenic species. We showed that the mobilization occurred under sulfate reducing conditions and the majority of the arsenic was in the form of thioarsenic species. Previous studies had predicted the presence of thioarsenic species but this study used robust field and laboratory methods to quantitatively determine the presence of thioarsenic species. During stimulation in wells with high arsenic the primary species were trithioarsenate and dithioarsenate. In wells with low levels of arsenic release thioarsenates were absent or minor components. Fortunately after the injection of acetate ended the aquifer would become less reducing and the arsenic concentrations would decrease to pre-injection levels. In aquifers where organic carbon is being added as a remedial method or as a contaminant the transient mobility of arsenic during sulfidogenesis should be considered especially in sulfate rich aquifers as this could impact downgradient water quality.

  4. Natural radioactivity in commercial granites extracted near old uranium mines: scientific, economic and social impact of disinformation.

    Science.gov (United States)

    Pereira, Dolores; Pereira, Alcides; Neves, Luis

    2015-04-01

    The study of radioactivity in natural stones is a subject of great interest from different points of view: scientific, social and economic. Several previous studies have demonstrated that the radioactivity is dependent, not only on the uranium content, but also on the structures, textures, minerals containing the uranium and degree of weathering of the natural stone. Villavieja granite is extracted in a village where uranium mining was an important activity during the 20th century. Today the mine is closed but the granite is still extracted. Incorrect information about natural radioactivity given to natural stone users, policy makers, construction managers and the general public has caused turmoil in the media for many years. This paper considers problems associated with the communication of reliable information, as well as uncertainties, on natural radioactivity to these audiences.

  5. Accident Analyses for Conversion of the University of Missouri Research Reactor (MURR) from Highly-Enriched to Low-Enriched Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Stillman, J. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Feldman, E. E. [Argonne National Lab. (ANL), Argonne, IL (United States); Jaluvka, D. [Argonne National Lab. (ANL), Argonne, IL (United States); Wilson, E. H. [Argonne National Lab. (ANL), Argonne, IL (United States); Foyto, L. P. [Univ. of Missouri, Columbia, MO (United States); Kutikkad, K. [Univ. of Missouri, Columbia, MO (United States); McKibben, J. C. [Univ. of Missouri, Columbia, MO (United States); Peters, N. J. [Univ. of Missouri, Columbia, MO (United States)

    2017-02-01

    This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members in the Research and Test Reactor Department at the Argonne National Laboratory (ANL) and the MURR Facility. MURR LEU conversion is part of an overall effort to develop and qualify high-density fuel within the U.S. High Performance Research Reactor Conversion (USHPRR) program conducted by the U.S. Department of Energy National Nuclear Security Administration’s Office of Material Management and Minimization (M3).

  6. Uranium Bio-accumulation and Cycling as revealed by Uranium Isotopes in Naturally Reduced Sediments from the Upper Colorado River Basin

    Science.gov (United States)

    Lefebvre, Pierre; Noël, Vincent; Jemison, Noah; Weaver, Karrie; Bargar, John; Maher, Kate

    2016-04-01

    Uranium (U) groundwater contamination following oxidized U(VI) releases from weathering of mine tailings is a major concern at numerous sites across the Upper Colorado River Basin (CRB), USA. Uranium(IV)-bearing solids accumulated within naturally reduced zones (NRZs) characterized by elevated organic carbon and iron sulfide compounds. Subsequent re-oxidation of U(IV)solid to U(VI)aqueous then controls the release to groundwater and surface water, resulting in plume persistence and raising public health concerns. Thus, understanding the extent of uranium oxidation and reduction within NRZs is critical for assessing the persistence of the groundwater contamination. In this study, we measured solid-phase uranium isotope fractionation (δ238/235U) of sedimentary core samples from four study sites (Shiprock, NM, Grand Junction, Rifle and Naturita, CO) using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). We observe a strong correlation between U accumulation and the extent of isotopic fractionation, with Δ238U up to +1.8 ‰ between uranium-enriched and low concentration zones. The enrichment in the heavy isotopes within the NRZs appears to be especially important in the vadose zone, which is subject to variations in water table depth. According to previous studies, this isotopic signature is consistent with biotic reduction processes associated with metal-reducing bacteria. Positive correlations between the amount of iron sulfides and the accumulation of reduced uranium underline the importance of sulfate-reducing conditions for U(IV) retention. Furthermore, the positive fractionation associated with U reduction observed across all sites despite some variations in magnitude due to site characteristics, shows a regional trend across the Colorado River Basin. The maximum extent of 238U enrichment observed in the NRZ proximal to the water table further suggests that the redox cycling of uranium, with net release of U(VI) to the groundwater by

  7. Cation-mediated conversion of the state of charge in uranium arene inverted-sandwich complexes

    Energy Technology Data Exchange (ETDEWEB)

    Camp, Clement; Mougel, Victor; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Maron, Laurent [LCPNO, CNRS and INSA, UPS, Universite de Toulouse (France)

    2013-12-16

    Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (3) and [K{sub 2}{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (2) with stoichiometric amounts of KC{sub 8} yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U{sup V}-(arene{sup 4-})-U{sup V}, KU{sup IV}-(arene{sup 4-})-U{sup V}, and K{sub 2}U{sup IV}-(arene{sup 4-})-U{sup IV} for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U{sup IV} mononuclear complex [U(OSi(OtBu){sub 3}){sub 3}(OTf)(thf){sub 2}] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Uranium removal from groundwater by natural clinoptilolite zeolite: Effects of pH and initial feed concentration

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, Lucy Mar [Department of Chemical Engineering, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003 (United States); Deng, Shuguang, E-mail: sdeng@nmsu.edu [Department of Chemical Engineering, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003 (United States); Parra, Ramona R. [Physical Science Laboratory, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003 (United States)

    2010-03-15

    Adsorption of uranium (VI) on a natural clinoptilolite zeolite from Sweetwater County, Wyoming was investigated. Batch experiments were conducted to study the effects of pH and initial feed concentrations on uranium removal efficiency. It was found that the clinoptilolite can neutralize both acidic and low basic water solutions through its alkalinity and ion-exchange reactions with U within the solution, and adsorption of uranium (VI) species on clinoptilolite not only depends on the pH but also the initial feed concentration. The highest uranium removal efficiency (95.6%) was obtained at initial uranium concentration of 5 mg/L and pH 6.0. The Langmuir adsorption isotherm model correlates well with the uranium adsorption equilibrium data for the concentration range of 0.1-500 mg/L. From the experimental data obtained in this work, it was found that the zeolite sample investigated in this work is a mixture of clinoptilolite-Na zeolite and mineral impurities with a relatively large specific surface area (BET of 18 m{sup 2}/g) and promising adsorption properties for uranium removal from contaminated water.

  9. The Non-Ergodic Nature of Internal Conversion

    DEFF Research Database (Denmark)

    Kuhlman, Thomas Scheby

    The absorption of light by molecules can induce ultrafast dynamics of coupled electronic and nuclear vibrational motion. The ultrafast nature in many cases rests on the importance of several potential energy surfaces in guiding the nuclear dynamics – a concept of central importance in many aspects...... of chemical reaction dynamics. In this thesis, we focus on the non-ergodic nature of internal conversion, i.e. the concept that the nuclear dynamics only sample a reduced phase space potentially resulting in localization of the dynamics in real space. In essence, this is a consequence of vibrational energy...... of primarily two parameters: the vibrational frequency and the energy difference between the Franck-Condon and equilibrium geometries of the upper electronic state. In the cyclopentadienes, the twisting of a single double bond is essential in reaching the conical intersection seam connecting the lowest excited...

  10. Comparison of potential radiological consequences from a spent-fuel repository and natural uranium deposits

    Energy Technology Data Exchange (ETDEWEB)

    Wick, O.J.; Cloninger, M.O.

    1980-09-01

    A general criterion has been suggested for deep geological repositories containing spent fuel - the repositories should impose no greater radiological risk than due to naturally occurring uranium deposits. The following analysis investigates the rationale of that suggestion and determines whether current expectations of spent-fuel repository performance are consistent with such a criterion. In this study, reference spent-fuel repositories were compared to natural uranium-ore deposits. Comparisons were based on intrinsic characteristics, such as radionuclide inventory, depth, proximity to aquifers, and regional distribution, and actual and potential radiological consequences that are now occurring from some ore deposits and that may eventually occur from repositories and other ore deposits. The comparison results show that the repositories are quite comparable to the natural ore deposits and, in some cases, present less radiological hazard than their natural counterparts. On the basis of the first comparison, placing spent fuel in a deep geologic repository apparently reduces the hazard from natural radioactive materials occurring in the earth's crust by locating the waste in impermeable strata without access to oxidizing conditions. On the basis of the second comparison, a repository constructed within reasonable constraints presents no greater hazard than a large ore deposit. It is recommended that if the naturally radioactive environment is to be used as a basis for a criterion regarding repositories, then this criterion should be carefully constructed. The criterion should be based on the radiological quality of the waters in the immediate region of a specific repository, and it should be in terms of an acceptable potential increase in the radiological content of those waters due to the existence of the repository.

  11. NIRS report of the criticality accident in a uranium conversion test plant in Tokai-mura

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    This report is a detailed account of the roles that National Institute of Radiological Sciences (NIRS) played at the criticality accident in the title, which occurred at around 10:35, on Sep. 30, 1999 and resulted in death of two workers after all, and is published to discharge NIRS responsibilities in regards to the accident. The accident caused many residents concern on their health and rumors had both social and economic consequences. The report involves chapters of detailed outline of the accident; demand for acceptance of the victims and communications until the identification of the criticality'' accident; the acceptance and initial treatment; the exposure dose estimation (based on acute symptoms, on physics, on chromosomal analyses and on neutron-activated dental metals, and detailed analyses for dose distribution); decision made for therapeutic strategies; cooperation with the Network Council for Radiation Emergency and with other medical facilities; the urgent import of medicine; treatment and processes (patients, nursing system and radiation injuries); radiation protection in medical facilities; response to nearby residents of the Plant; international response; press release; Uranium Processing Plant Criticality Accident Investigation Committee and the Health Management Committee organized by the Nuclear Safety Commission; handling of information; and radiation emergency medical preparedness at the NIRS (future issues and prospect). The report is hopefully useful in preventing the occurrence of future accidents. (N.I.)

  12. The report of the criticality accident in a uranium conversion test plant in Tokai-mura

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Hajime (ed.) [National Inst. of Radiological Sciences, Chiba (Japan). Research Center for Charged Particle Therapy; Akashi, Makoto (ed.) [National Inst. of Radiological Sciences, Chiba (Japan). Research Center for Radiation Emergency Medicine

    2002-03-01

    The criticality accident in the title occurred at around 10:35, on Sep. 30, 1999, cost the lives of two workers and caused many residents concern on their health. Moreover, rumors had both social and economic consequences. This report is a detailed account of the roles that many individuals and groups in the National Institute of Radiological Sciences (NIRS) performed in a range of the areas, and is published to discharge NIRS responsibilities in regards to the accident. The report involves chapters of detailed outline of the accident; acceptance of the victims and communications until the identification of the ''criticality'' accident; initial treatment; dose estimation (medical, hematological, physical and biological ones and that by dental metals activated by the neutron); decision making for therapeutic strategies; cooperation with the Network Council for Radiation Emergency Medicine and other medical facilities; emergency importation of medical supplies; treatment and progress (nursing system and radiation injuries); protection from radiation in medical facilities; response to nearby residents of the Plant; international response; press release; Uranium Processing Plant Criticality Accident Investigation Committee and the Health Management Committee organized by the Nuclear Safety Commission; handling of information; and radiation emergency medical preparedness at the NIRS (future issues and prospect). The report is hoped to be useful in preventing the occurrence of future accidents. (K.H.)

  13. Natural Radioactivity in Soil and Water from Likuyu Village in the Neighborhood of Mkuju Uranium Deposit

    Directory of Open Access Journals (Sweden)

    Najat K. Mohammed

    2013-01-01

    Full Text Available The discovery of high concentration uranium deposit at Mkuju, southern part of Tanzania, has brought concern about the levels of natural radioactivity at villages in the neighborhood of the deposit. This study determined the radioactivity levels of 30 soil samples and 20 water samples from Likuyu village which is 54 km east of the uranium deposit. The concentrations of the natural radionuclides 238U, 232Th, and 40K were determined using low level gamma spectrometry of the Tanzania Atomic Energy Commission (TAEC Laboratory in Arusha. The average radioactivity concentrations obtained in soil samples for 238U (51.7 Bq/kg, 232Th (36.4 Bq/kg, and 40K (564.3 Bq/kg were higher than the worldwide average concentrations value of these radionuclides reported by UNSCEAR, 2000. The average activity concentration value of 238U (2.35 Bq/L and 232Th (1.85 Bq/L in water samples was similar and comparable to their mean concentrations in the control sample collected from Nduluma River in Arusha.

  14. An Intelligent Natural Language Conversational System for Academic Advising

    Directory of Open Access Journals (Sweden)

    Edward M. Latorre-Navarro

    2015-01-01

    Full Text Available Academic advisors assist students in academic, professional, social and personal matters. Successful advising increases student retention, improves graduation rates and helps students meet educational goals. This work presents an advising system that assists advisors in multiple tasks using natural language. This system features a conversational agent as the user interface, an academic advising knowledge base with a method to allow the users to contribute to it, an expert system for academic planning, and a web design structure for the implementation platform. The system is operational for several hundred students from a university department. The system performed well, obtaining close to 80%, on the traditional language processing measures of precision, recall, accuracy and F1 score. Assessment from the constituencies showed positive and assuring reviews. This work provides an assessment and technological solution to the academic advising field, i.e., the first-known advising multi-task conversational system with adaptive measures for improvement. The evaluation in a real-world scenario shows its viability, and initiated the development of a corpus for academic advising, valuable for the academic and language processing research communities.

  15. An eco-friendly process for natural gas conversion

    Energy Technology Data Exchange (ETDEWEB)

    Yao, S.; Nakayama, A.; Suzuki, E. [Research Institute of Innovative Technology for the Earth, Kyoto (Japan). Catalysis Science Laboratory

    2001-07-01

    An eco-friendly process has been developed to convert methane, the major component of natural gas, to acetylene and hydrogen using a high frequency pulsed plasma. Acetylene is an important raw material in industry that is manufactured mainly by the reaction of calcium carbide with water. Acetylene is also manufactured by thermal cracking of hydrocarbons, or by partial oxidation of methane. These conventional processes require severe reaction conditions (a very high reaction temperature) and emit large amounts of greenhouse gas. The new process can convert methane to acetylene and hydrogen with a conversion efficiency of 52.8%, an acetylene selectivity of 91.8%, and a hydrogen ratio of 4.15 moles per mole acetylene at room temperature and atmospheric pressure. No environmental pollutant is emitted. 14 refs., 1 fig., 3 tabs.

  16. Bioaccumulation and biological effects in the earthworm Eisenia fetida exposed to natural and depleted uranium

    Energy Technology Data Exchange (ETDEWEB)

    Giovanetti, Anna, E-mail: anna.giovanetti@enea.i [ENEA, Institute of Radiation Protection, CR Casaccia Via Anguillarese 301, 00123 Rome (Italy); Fesenko, Sergey [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-2444 Seibersdorf (Austria); Cozzella, Maria L. [ENEA, National Institute for Metrology of Ionizing Radiation, CR Casaccia Via Anguillarese 301, 00123 Rome (Italy); Asencio, Lisbet D. [Centro de Estudios Ambientales, Carretera a Castillo de Jagua, CP. 59350 C. Nuclear, Cienfuegos (Cuba); Sansone, Umberto [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-2444 Seibersdorf (Austria)

    2010-06-15

    The accumulations of both natural (U) and depleted (DU) uranium in the earthworms (Eisenia fetida) were studied to evaluate corresponding biological effects. Concentrations of metals in the experimental soil ranged from 1.86 to 600 mg kg{sup -1}. Five biological endpoints: mortality, animals' weight increasing, lysosomal membrane stability by measuring the neutral red retention time (the NRRT), histological changes and genetic effects (Comet assay) were used to evaluate biological effects in the earthworms after 7 and 28 days of exposure. No effects have been observed in terms of mortality or weight reduction. Cytotoxic and genetic effects were identified at quite low U concentrations. For some of these endpoints, in particular for genetic effects, the dose (U concentration)-effect relationships have been found to be non-linear. The results have also shown a statistically significant higher level of impact on the earthworms exposed to natural U compared to depleted U.

  17. A Case Study on the Nature of Informal Conversation in an Organization Utilizing Microblogging Technology

    Science.gov (United States)

    Dembeck, Thomas J.

    2013-01-01

    The purpose of this case study was to determine the nature of conversations that occur within an organizational microblog and compare them to traditional informal conversations. Since informal conversations are closely associated with reaction to change, this study explored how organizational microblog conversations may be understood to affect…

  18. A Case Study on the Nature of Informal Conversation in an Organization Utilizing Microblogging Technology

    Science.gov (United States)

    Dembeck, Thomas J.

    2013-01-01

    The purpose of this case study was to determine the nature of conversations that occur within an organizational microblog and compare them to traditional informal conversations. Since informal conversations are closely associated with reaction to change, this study explored how organizational microblog conversations may be understood to affect…

  19. Modeling conversion of ammonium diuranate (ADU) into uranium dioxide (UO2) powder

    Science.gov (United States)

    Hung, Nguyen Trong; Thuan, Le Ba; Khoai, Do Van; Lee, Jin-Young; Jyothi, Rajesh Kumar

    2016-10-01

    In the paper, Brandon mathematical model that describes the relationship between the essential fabrication parameters [reduction temperature (TR), calcination temperature (TC), calcination time (tC) and reduction time (tR)] and specific surface area of ammonium diuranate (ADU)-derived UO2 powder products was established. The proposed models can be used to predict and control the specific surface area of UO2 powders prepared through ADU route. Suitable temperatures for conversion of ADU and ammonium uranyl carbonate (AUC) was examined with the proposed model through assessment of the sinterability of UO2 powders.

  20. The capitalist world aggregate supply and demand model for natural uranium

    Energy Technology Data Exchange (ETDEWEB)

    Amavilah, V.H.S. [Arizona Univ., Tucson, AZ (United States). Dept. of Mining and Geological Engineering]|[Ore Body Engineering Ltd., Tucson, AZ (United States)

    1995-07-01

    Seemingly unrelated regression associating U supply and demand to own price, net nuclear electric consumption, generating capacity, competing fuel prices, and electricity prices is postulated. Coal prices are found to influence uranium price significantly. Composite energy prices affect uranium demand via either nuclear electric consumption or nuclear generating capacity. Electricity prices affect uranium demand directly in a negative fashion. (author).

  1. Radon as a natural tracer for gas transport within uranium waste rock piles.

    Science.gov (United States)

    Silva, N C; Chagas, E G L; Abreu, C B; Dias, D C S; Lopez, D; Guerreiro, E T Z; Alberti, H L C; Braz, M L; Branco, O; Fleming, P

    2014-07-01

    Acid mine drainage (AMD) has been identified as the main cause for outflow of acid water and radioactive/non-radioactive contaminants. AMD encompasses pyrites oxidation when water and oxygen are available. AMD was identified in uranium waste rock piles (WRPs) of Indústrias Nucleares do Brasil-Caldas facility (Brazilian uranium mine), resulting in high costs for water treatment. AMD reduction is the main challenge, and scientific investigation has been conducted to understand oxygen and water transportation within WRPs, where 222Rn is used as natural tracer for oxygen transportation. The study consists of soil radon gas mapping in the top layer of WRP4 using active soil gas pumping, radon adsorption in active charcoal and 222Rn determination using high-resolution gamma-ray spectrometry. A sampling network of 71 points was built where samples were collected at a depth of 40 cm. Soil radon gas concentration ranged from 33.7 to 1484.2 kBq m(-3) with mean concentration of 320.7±263.3 kBq m(-3).

  2. Uranium(IV) adsorption by natural organic matter in anoxic sediments

    Energy Technology Data Exchange (ETDEWEB)

    Bone, Sharon E.; Dynes, James J.; Cliff, John; Bargar, John R.

    2017-01-09

    Uranium is an important carbon-free fuel source and environmental contaminant that accumulates in the tetravalent state, U(IV), in anoxic sediments, such as ore deposits, marine basins, and contaminated aquifers. However, little is known about the speciation of U(IV) in low-temperature geochemical environments, inhibiting the development of a conceptual model of U behavior. Until recently, U(IV) was assumed to exist predominantly as the sparingly soluble mineral uraninite (UO2+x) in anoxic sediments; however, studies now show that this is not often the case. Yet a model of U(IV) speciation in the absence of mineral formation under field-relevant conditions has not yet been developed. Uranium(IV) speciation controls its reactivity, particularly its susceptibility to oxidative mobilization, impacting its distribution and toxicity. Here we show adsorption to organic carbon and organic carbon-coated clays dominate U(IV) speciation in an organic-rich natural substrate under field-relevant conditions. Whereas previous research assumed that U(IV) speciation is dictated by the mode of reduction (i.e., whether reduction is mediated by microbes or by inorganic reductants), our results demonstrate that mineral formation can be diminished in favor of adsorption, regardless of reduction pathway. Projections of U transport and bioavailability, and thus its threat to human and ecosystem health, must consider U(IV) adsorption to organic matter within the sediment environment.

  3. Uranium isotopic data in uraninite spent fuel from the Bangombe natural nuclear reactor (Gabon) and its surroundings

    Science.gov (United States)

    Fernandez-Diaz; Quejido; Crespo; Perez del Villar L; Martin-Sanchez; Lozano

    2000-07-01

    In the framework of the "Oklo-Natural Analogue Phase II" Project, uraninite from the Bangombe natural reactor and samples from its host rock were analyzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha spectrometry. There were several objectives for this work: (i) to validate the 235U/238U isotopic ratios obtained by these techniques; (ii) to test the use of the 235U/238U ratio of uraninite as a tracer of migration/retention processes of uranium from the source term to the far field; (iii) to evaluate the most recent migration/retention processes of uranium in the system by U-series disequilibrium.

  4. Uranium isotopic data in uraninite spent fuel from the Bangombe natural nuclear reactor (Gabon) and its surroundings

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Diaz, M.; Quejido, A.J.; Crespo, M.T.; Villar, L.P. del; Martin-Sanchez, A. E-mail: ams@unex.es; Lozano, J.C

    2000-07-15

    In the framework of the 'Oklo-Natural Analogue Phase II' Project, uraninite from the Bangombe natural reactor and samples from its host rock were analyzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha spectrometry. There were several objectives for this work: (i) to validate the {sup 235}U/{sup 238}U isotopic ratios obtained by these techniques; (ii) to test the use of the {sup 235}U/{sup 238}U ratio of uraninite as a tracer of migration/retention processes of uranium from the source term to the far field; (iii) to evaluate the most recent migration/retention processes of uranium in the system by U-series disequilibrium.

  5. Characterization of Natural Attenuation in a uranium-contaminated site by means of Induced Polarization Imaging

    Science.gov (United States)

    Flores Orozco, Adrián; Bücker, Matthias; Williams, Kenneth

    2014-05-01

    Field experiments at the U.S. Department of Energy's (DOE) Integrated Field Research Challenge site (IFRC) in Rifle, Colorado (USA) have repeatedly demonstrated the ability of microorganisms to reductively immobilize uranium (U) in U tailings-contaminated groundwater accompanying organic carbon amendment. At the same time, geophysical monitoring during such amendment experiments has proven that Induced Polarization (IP) datasets can provide valuable information regarding geochemical changes induced by stimulated microbial activity, such as precipitation of metallic minerals (e.g. FeS) and accumulation of reactive, electroactive ions (Fe[II]). Based on these findings, we present a novel, modified application of the IP imaging method. Specifically, we utilized an IP characterization approach to delineate areas where fluvially deposited organic material, within aquifer sediments, naturally stimulates the activity of subsurface microflora, leading to both the natural immobilization of uranium and accumulation of reduced end-products (minerals and pore fluids) capable of generating anomalous IP signatures. These so-called 'naturally reduced zones' (NRZ's) are characterized by elevated rates of microbial activity relative to sediments having a lower concentration of organic matter. As noted and based on our previous experiments at the site, the accumulation of metallic minerals represents suitable targets for the exploration with IP tomographic methods. Here, we explore the application of the IP imaging method for the characterization of NRZ's at the scale of the floodplain. We present imaging results obtained through the inversion of 70 independent lines distributed along the floodplain (~600 m2). Imaging results are validated through comparisons with lithological data obtained from wells drilled at the site and laboratory analysis of sediment and groundwater samples. Our results show the applicability of the IP method for characterizing regions of the subsurface having

  6. Radiological survey of the inactive uranium-mill tailings at the Spook site, Converse County, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Haywood, F.F.; Christian, D.J.; Chou, K.D.; Ellis, B.S.; Lorenzo, D.; Shinpaugh, W.H.

    1980-05-01

    Results of a radiological survey performed at the Spook site in Converse County, Wyoming, in June 1976, are presented. The mill at this site was located a short distance from the open-pit mine where the ore was obtained and where part of the tailings was dumped into the mine. Several piles of overburden or low-grade ore in the vicinity were included in the measurements of above-ground gamma exposure rate. The average exposure rate over these piles varied from 14 ..mu..R/hr, the average background exposure rate for the area, to 140 ..mu..R/hr. The average exposure rate for the tailings and former mill area was 220 ..mu..R/hr. Movement of tailings particles down dry washes was evident. The calculated concentration of /sup 226/Ra in ten holes as a function of depth is presented graphically.

  7. Elimination of natural uranium and {sup 226}Ra from contaminated waters by rhizofiltration using Helianthus annuus L

    Energy Technology Data Exchange (ETDEWEB)

    Vera Tome, F. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Blanco Rodriguez, P. [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Lozano, J.C. [Laboratorio de Radiactividad Ambiental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain)

    2008-04-15

    The elimination of natural uranium and {sup 226}Ra from contaminated waters by rhizofiltration was tested using Helianthus annuus L. (sunflower) seedlings growing in a hydroponic medium. Different experiments were designed to determine the optimum age of the seedlings for the remediation process, and also to study the principal way in which the radionuclides are removed from the solution by the sunflower roots. In every trial a precipitate appeared which contained a major fraction of the natural uranium and {sup 226}Ra. The results indicated that the seedlings themselves induced the formation of this precipitate. When four-week-old seedlings were exposed to contaminated water, a period of only 2 days was sufficient to remove the natural uranium and {sup 226}Ra from the solution: about 50% of the natural uranium and 70% of the {sup 226}Ra were fixed in the roots, and essentially the rest was found in the precipitate, with only very small percentages fixed in the shoots and left in solution.

  8. Cell-metal interactions: A comparison of natural uranium to other common metals in renal cells and bone osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Milgram, S. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Carriere, M. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Thiebault, C. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Berger, P. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Khodja, H. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Gouget, B. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France)]. E-mail: barbara.gouget@cea.fr

    2007-07-15

    Uranium acute intoxication has been documented to induce nephrotoxicity. Kidneys are the main target organs after short term exposures to high concentrations of the toxic, while chronic exposures lead to its accumulation in the skeleton. In this paper, chemical toxicity of uranium is investigated for rat osteoblastic bone cells and compared to results previously obtained on renal cells. We show that bone cells are less sensitive to uranium than renal cells. The influence of the chemical form on U cytotoxicity is demonstrated. For both cell types, a comparison of uranium toxicity with other metals or metalloids toxicities (Mn, Ni, Co, Cu, Zn, Se and Cd) permits classification of Cd, Zn, Se{sup IV} and Cu as the most toxic and Ni, Se{sup VI}, Mn and U as the least toxic. Chemical toxicity of natural uranium proves to be far less than that of cadmium. To try to explain the differences in sensitivities observed between metals and different cell types, cellular accumulations in cell monolayers are quantified by inductively coupled plasma-mass spectroscopy (ICP-MS), function of time or function of dose: lethal doses which simulate acute intoxications and sub-lethal doses which are more realistic with regard to environmentally metals concentrations. In addition to being more resistant, bone cells accumulated much more uranium than did renal cells. Moreover, for both cell models, Mn, U-citrate and U-bicarbonate are strongly accumulated whereas Cu, Zn and Ni are weakly accumulated. On the other hand, a strong difference in Cd behaviour between the two cell types is shown: whereas Cd is very weakly accumulated in bone cells, it is very strongly accumulated in renal cells. Finally, elemental distribution of the toxics is determined on a cellular scale using nuclear microprobe analysis. For both renal and osteoblastic cells, uranium was accumulated in as intracellular precipitates similar to those observed previously by SEM/EDS.

  9. Sorption/desorption processes of uranium in clayey samples of the Bangombe natural reactor zone, Gabon

    Energy Technology Data Exchange (ETDEWEB)

    Nero, M. del [Inst. de Recherches Subatomiques, CNRS/IN2P3, Strasbourg (France); Salah, S.; Clement, A.; Gauthier-Lafaye, F. [Centre de Geochimie de la Surface, CNRS, Strasbourg (France); Miura, T. [National Lab. for High Energy Physics, Tsukuba-Shi Ibaraki-Ken (Japan)

    1999-07-01

    Experimental studies have been undertaken in order to provide new insights into the relative efficiency of the different mineral phases and sorption processes for the control of U retention in the weathered zones surrounding the natural nuclear reactor at Bangombe (Oklo, Gabon). Clayey and Fe-oxihydroxides rich samples from the oxidizing weathered zones located above the reactor were examined. An experimental study of uranium adsorption/desorption processes in these samples was carried out using a uranium isotope exchange technique in order to estimate the proportion of uranium adsorbed on mineral surfaces. A sequential extraction technique was used to identify the major U-containing minerals in the samples. In the U-rich iron crust rocks close to the reactor, the fraction of total uranium adsorbed at mineral surfaces is small. Extraction experiments reveal that a large part of uranium is associated to Fe-oxihydroxides, to minor P-rich phases, and presumably to Mn-oxihydroxides. A possible mechanism for U retention is an incorporation into the structure of iron oxihydroxides and/or of ferric phosphates occurring as surface precipitates on Fe-oxihydroxides. Traces of autunite-like mineral are also present in the zone. For the clayey samples in the weathering profile, it may be inferred that several processes and minerals contribute significantly to U retention: adsorption processes occurring mainly at clay surfaces, association with traces of Mn-containing carboantes and iron oxihydroxides. A significant proportion of total U is adsorbed at mineral surfaces and is thereby easily accessible to weathering solutions. In a second part of this work, {sup 233}U sorption data obtained on a Fe- and Mn-poor illitic Bangombe sample were modeled using a surface complexation modeling approach. As a first approximation, it was assumed in modeling that uranyl binding occurs at aluminol edge sites of the illite component. The binding constant required for modeling was firstly

  10. Uranium, depleted uranium, biological effects; Uranium, uranium appauvri, effets biologiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Physicists, chemists and biologists at the CEA are developing scientific programs on the properties and uses of ionizing radiation. Since the CEA was created in 1945, a great deal of research has been carried out on the properties of natural, enriched and depleted uranium in cooperation with university laboratories and CNRS. There is a great deal of available data about uranium; thousands of analyses have been published in international reviews over more than 40 years. This presentation on uranium is a very brief summary of all these studies. (author)

  11. Analysis and exploitation of bacterial population from natural uranium-rich soils: selection of a model specie; Analyse et exploitation des populations bacteriennes de sols riches en uranium: selection d'une espece modele

    Energy Technology Data Exchange (ETDEWEB)

    Mondani, L.

    2010-11-23

    It is well known that soils play a key role in controlling the mobility of toxic metals and this property is greatly influenced by indigenous bacterial communities. This study has been conducted on radioactive and controls soils, collected in natural uraniferous areas (Limousin). A physico-chemical and mineralogical analysis of soils samples was carried out.The structure of bacterial communities was estimated by Denaturing Gradient Gel Electrophoresis (DGGE). The community structure is remarkably more stable in the uranium-rich soils than in the control ones, indicating that uranium exerts a high selection from the soils was constructed and screened for uranium resistance in order to study bacteria-uranium interactions. Scanning electron microscopy revealed that a phylo-genetically diverse set of uranium-resistant species ware able to chelate uranium at the cell surface. (author) [French] On sait que les sols et les populations bacteriennes indigenes ont une influence sur la mobilite des metaux, donc sur leur toxicite. Cette etude a ete menee sur des sols uraniferes et controles collectes dans le Limousin (regions naturellement riches en uranium ). Une analyse physico-chimique et mineralogique des echantillons de sol a ete realisee. La structure des communautes bacteriennes a ete etudiee par electrophorese en gradient de denaturant (DGGE). La structure des communautes est remarquablement stable dans les sols uraniferes, ce qui indique que l'uranium exerce une forte pression de selection. D'autre part, une collection de bacteries cultivables a ete realisee a partir des sols, puis criblee pour la resistance a l'uranium, dans le but d'etudier les interactions entre bacteries et uranium. Des observations en Microscopie electronique a Balayage ont mis en evidence differents mecanismes de chelation de l'uranium a la surface cellulaire

  12. Compilation of Requirements for Safe Handling of Fluorine and Fluorine-Containing Products of Uranium Hexafluoride Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Ferrada, J.J.

    2000-04-03

    Public Law (PL) 105-204 requires the U.S. Department of Energy to develop a plan for inclusion in the fiscal year 2000 budget for conversion of the Department's stockpile of depleted uranium hexafluoride (DUF{sub 6}) to a more stable form over an extended period. The conversion process into a more stable form will produce fluorine compounds (e.g., elemental fluorine or hydrofluoric acid) that need to be handled safely. This document compiles the requirements necessary to handle these materials within health and safety standards, which may apply in order to ensure protection of the environment and the safety and health of workers and the public. Fluorine is a pale-yellow gas with a pungent, irritating odor. It is the most reactive nonmetal and will react vigorously with most oxidizable substances at room temperature, frequently with ignition. Fluorine is a severe irritant of the eyes, mucous membranes, skin, and lungs. In humans, the inhalation of high concentrations causes laryngeal spasm and broncospasms, followed by the delayed onset of pulmonary edema. At sublethal levels, severe local irritation and laryngeal spasm will preclude voluntary exposure to high concentrations, unless the individual is trapped or incapacitated. A blast of fluorine gas on the shaved skin of a rabbit causes a second degree burn. Lower concentrations cause severe burns of insidious onset, resulting in ulceration, similar to the effects produced by hydrogen fluoride. Hydrofluoric acid is a colorless, fuming liquid or gas with a pungent odor. It is soluble in water with release of heat. Ingestion of an estimated 1.5 grams produced sudden death without gross pathological damage. Repeated ingestion of small amounts resulted in moderately advanced hardening of the bones. Contact of skin with anhydrous liquid produces severe burns. Inhalation of AHA or aqueous hydrofluoric acid mist or vapors can cause severe respiratory tract irritation that may be fatal. Based on the extreme chemical

  13. Improving Natural Uranium Utilization By Using Thorium in Low Moderation PWRs - A Preliminary Neutronic Scoping Study

    Energy Technology Data Exchange (ETDEWEB)

    Gilles Youinou; Ignacio Somoza

    2010-10-01

    The Th-U fuel cycle is not quite self-sustainable when used in water-cooled reactors and with fuel burnups higher than a few thousand of MWd/t characteristic of CANDU reactors operating with a continuous refueling. For the other industrially mature water-cooled reactors (i.e. PWRs and BWRs) it is economically necessary that the fuel has enough reactivity to reach fuel burnups of the order of a few tens of thousand of MWd/t. In this particular case, an additional input of fissile material is necessary to complement the bred fissile U-233. This additional fissile material could be included in the form of Highly Enriched Uranium (HEU) at the fabrication of the Th-U fuel. The objective of this preliminary neutronic scoping study is to determine (1) how much HEU and, consequently, how much natural uranium is necessary in such Th-U fuel cycle with U recycling and (2) how much TRansUranics (TRU=Pu, Np, Am and Cm) are produced. These numbers are then compared with those of a standard UO2 PWR. The thorium reactors considered have a homogeneous hexagonal lattice made up of the same (Th-U)O2 pins. Furthermore, at this point, we are not considering the use of blankets inside or outside the core. The lattice pitch has been varied to estimate the effect of the water-to-fuel volume ratio, and light water as well as heavy water have been considered. For most cases, an average burnup at discharge of 45,000 MWd/t has been considered.

  14. Uranium industry annual 1998

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-22

    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.

  15. Authentic ESL Spoken Materials: Soap Opera and Sitcom versus Natural Conversation

    Science.gov (United States)

    Al-Surmi, Mansoor Ali

    2012-01-01

    TV shows, especially soap operas and sitcoms, are usually considered by ESL practitioners as a source of authentic spoken conversational materials presumably because they reflect the linguistic features of natural conversation. However, practitioners might be faced with the dilemma of how to evaluate whether such conversational materials reflect…

  16. Authentic ESL Spoken Materials: Soap Opera and Sitcom versus Natural Conversation

    Science.gov (United States)

    Al-Surmi, Mansoor Ali

    2012-01-01

    TV shows, especially soap operas and sitcoms, are usually considered by ESL practitioners as a source of authentic spoken conversational materials presumably because they reflect the linguistic features of natural conversation. However, practitioners might be faced with the dilemma of how to evaluate whether such conversational materials reflect…

  17. The Palmottu natural analogue project. The behaviour of natural radionuclides in and around uranium deposits. Summary report 1992-1994

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, R.; Ruskeeniemi, T.; Ahonen, L. [Geological Survey of Finland, Espoo (Finland); Suksi, J. [Helsinki Univ. (Finland). Lab. of Radiochemistry; Niini, H. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Engineering Geology and Geophysics; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland); Jakobsson, K. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

    1995-06-01

    The Palmottu U-Th mineralization at Nummi-Pusula, southwestern Finland, has been studied as a natural analogue to deep disposal of radioactive wastes since 1988. The report gives a summary of the results of investigations carried out during the years 1992-1994. The Palmottu Analogue Project aims at a more profound understanding of radionuclide transport processes in fractured crystalline bedrock. The essential factors controlling transport are groundwater flow and interaction between water and rock. Accordingly, the study includes structural interpretations based in part on geophysical measurements, hydrological studies including hydraulic downhole measurements, flow modelling, hydrogeochemical characterization of groundwater, uranium chemistry and colloid chemistry, mineralogical studies, geochemical interpretation and modelling, including paleohydrogeological aspects, and studies of radionuclide mobilization and migration processes including numerical simulations. The project has produced a large amount of data related to natural analogue aspects. The data obtained have already been utilized in developing logical conceptual ideas of the time frames and processes operating in the bedrock of the site. (61 refs., 24 figs., 8 tabs.).

  18. Novel Poly(imide dioxime) Sorbents: Development and testing for enhanced extraction of uranium from natural seawater

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sadananda; Brown, Suree S.; Mayes, Richard T.; Janke, Christopher J.; Tsouris, Costas; Kuo, Li-Jung; Gill, Gary A.; Dai, Sheng

    2016-04-09

    A new series of amidoxime-based polymer adsorbents were synthesized at the Oak Ridge National Laboratory (ORNL) by electron beam induced grafting of acrylonitrile and itaconic acid onto polyethylene fiber. Hydroxylamine derivatives of poly(acrylonitrile) (PAN) moiety are demonstrated to possess two kinds of functional groups: open-chain amidoxime and cyclic imide dioxime. The open-chain amidoxime is shown to convert to imide dioxime on heat treatment in the presence of an aprotic solvent, like dimethylsulfoxide (DMSO). The formation of amidoxime and imide dioxime was confirmed by 13-C CPMAS spectra. The adsorbents were evaluated for uranium adsorption efficiency at ORNL with simulated seawater spiked with 8 ppm uranium and 5 gallon seawater in a batch reactor, and in flow-through columns with natural seawater at the Marine Science Laboratory (MSL) of Pacific Northwest National Laboratory (PNNL) at Sequim Bay, WA. The DMSO-heat-treated sorbents adsorbed uranium as high as 4.48 g-U/kg-ads. from seawater. Experimental evidence is presented that the poly(imide dioxime) is primarily responsible for enhanced uranium adsorption capacity from natural seawater. The conjugated system in the imide dioxime ligand possesses increased electron donation ability, which is believed to significantly enhance the uranyl coordination in seawater

  19. Organic matter and containment of uranium and fissiogenic isotopes at the Oklo natural reactors

    Science.gov (United States)

    Nagy, B.; Gauthier-Lafaye, F.; Holliger, P.; Davis, D.W.; Mossman, D.J.; Leventhal, J.S.; Rigali, M.J.; Parnell, J.

    1991-01-01

    SOME of the Precambrian natural fission reactors at Oklo in Gabon contain abundant organic matter1,2, part of which was liquefied at the time of criticality and subsequently converted to a graphitic solid3,4. The liquid organic matter helps to reduce U(VI) to U(IV) from aqueous solutions, resulting in the precipitation of uraninite5. It is known that in the prevailing reactor environments, precipitated uraninite grains incorporated fission products. We report here observations which show that these uraninite crystals were held immobile within the resolidified, graphitic bitumen. Unlike water-soluble (humic) organic matter, the graphitic bituminous organics at Oklo thus enhanced radionu-clide containment. Uraninite encased in solid graphitic matter in the organic-rich reactor zones lost virtually no fissiogenic lan-thanide isotopes. The first major episode of uranium and lead migration was caused by the intrusion of a swarm of adjacent dolerite dykes about 1,100 Myr after the reactors went critical. Our results from Oklo imply that the use of organic, hydrophobic solids such as graphitic bitumen as a means of immobilizing radionuclides in pretreated nuclear waste warrants further investigation. ?? 1991 Nature Publishing Group.

  20. The feasibility study of small long-life gas cooled fast reactor with mixed natural Uranium/Thorium as fuel cycle input

    Science.gov (United States)

    Ariani, Menik; Su'ud, Zaki; Waris, Abdul; Khairurrijal, Monado, Fiber; Sekimoto, Hiroshi

    2012-06-01

    A conceptual design study of Gas Cooled Fast Reactors with Modified CANDLE burn-up scheme has been performed. In this study, design GCFR with Helium coolant which can be continuously operated by supplying mixed Natural Uranium/Thorium without fuel enrichment plant or fuel reprocessing plant. The active reactor cores are divided into two region, Thorium fuel region and Uranium fuel region. Each fuel core regions are subdivided into ten parts (region-1 until region-10) with the same volume in the axial direction. The fresh Natural Uranium and Thorium is initially put in region-1, after one cycle of 10 years of burn-up it is shifted to region-2 and the each region-1 is filled by fresh natural Uranium/Thorium fuel. This concept is basically applied to all regions in both cores area, i.e. shifted the core of ith region into i+1 region after the end of 10 years burn-up cycle. For the next cycles, we will add only Natural Uranium and Thorium on each region-1. The calculation results show the reactivity reached by mixed Natural Uranium/Thorium with volume ratio is 4.7:1. This reactor can results power thermal 550 MWth. After reactor start-up the operation, furthermore reactor only needs Natural Uranium/Thorium supply for continue operation along 100 years.

  1. Modeling of direct conversion of the uranium fission product kinetic energy to laser radiation energy in an argon–xenon dusty plasma with uranium nanoparticles

    Directory of Open Access Journals (Sweden)

    M.N. Slyunyaev

    2015-12-01

    It is the first time that amplifying properties of a laser-active spatially heterogeneous nuclear-excited moving argon–xenon medium, containing uranium nanoparticles and irradiated by neutrons, have been studied. As shown by the investigation results, the LR intensity amplification may be sevenfold and more in steady-state conditions. Such a high value makes it possible to state that this medium can be used not only in a nuclear-pumped laser but also in the mode of a single-pass nuclear-pumped laser amplifier.

  2. Methods for natural gas and heavy hydrocarbon co-conversion

    Science.gov (United States)

    Kong, Peter C.; Nelson, Lee O.; Detering, Brent A.

    2009-02-24

    A reactor for reactive co-conversion of heavy hydrocarbons and hydrocarbon gases and includes a dielectric barrier discharge plasma cell having a pair of electrodes separated by a dielectric material and passageway therebetween. An inlet is provided for feeding heavy hydrocarbons and other reactive materials to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a variety of light sources for providing ultraviolet light within the discharge plasma cell. Methods for upgrading heavy hydrocarbons are also disclosed.

  3. The Alligator rivers natural analogue - Modelling of uranium and thorium migration in the weathered zone at Koongarra

    Energy Technology Data Exchange (ETDEWEB)

    Skagius, K.; Lindgren, M.; Boghammar, A.; Brandberg, F.; Pers, K.; Widen, H. [Kemakta, Stockholm (Sweden)

    1993-08-01

    The Koongarra Uranium Deposit in the Alligator Rivers Region in the Northern Territory of Australia is a natural analogue being investigated with the aim to contribute to the understanding of the scientific basis for the long term prediction of radionuclide migration within geological environments relevant to radioactive waste repositories. The dispersion of uranium and decay products in the weathered zone has been modelled with a simple advection-dispersion-reversible sorption model and with a model extended to also consider {alpha}-recoil and transfer of radionuclides between different mineral phases of the rock. The modelling work was carried out in several iterations, each including a review of available laboratory and field data, selection of the system to be modelled and suitable model, and a comparison of modelling results with field observations. Uranium concentrations in bulk rock calculated with the simple advection-dispersion- reversible sorption model were in fair agreement with observed data using parameter values within ranges recommended based on independent interpretations. The advection-dispersion-reversible sorption model is a large simplification of the system among other things because the partitioning of radionuclides between water and solid phase is described with a sorption equilibrium term only. Although the results from this study not are enough to validate simple performance assessment models in a strict sense, it has been shown that even simple models are able to describe the present day distribution of uranium in the weathered zone at Koongarra. 23 refs, 61 figs.

  4. Correlation of radioactive waste treatment costs and the environmental impact of waste effluents in the nuclear fuel cycle: conversion of recycle uranium to UF/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Roddy, J.W.; Blanco, R.E.; Finney, B.C.; Hill, G.S.; Moore, R.E.; Witherspoon, J.P.

    1977-04-01

    A cost/benefit study was made to determine the cost and effectiveness of various radioactive waste (radwaste) treatment systems for decreasing the amount of radioactive materials released from a model recycle uranium conversion and uranium hexafluoride (UF/sub 6/) production plant and to determine the radiological impact (dose commitment) of the released radioactive materials on the environment. This study is designed to assist the US NRC in defining the term ''as low as reasonably achievable'' as it applies to these nuclear facilities. The base case model plant is representative of a licensable UF/sub 6/ production plant and has an annual capacity of 1500 metric tons of uranium. Additional radwaste treatment systems are added to the base case plant in a series of case studies to decrease the amounts of radioactive materials released and to reduce the radiological dose commitment to the population in the surrounding area. The cost for the added waste treatment operations and the corresponding dose commitments is calculated for each case. In the final analysis, radiological dose is plotted vs the annual cost for treatment of the radwastes. The status of the radwaste treatment methods used in the case studies is discussed. The methodology used in estimating the costs is presented. (34 tables, 11 figs.)

  5. Designing separation process of radioactive Iodine produced from irradiation of natural uranium

    CERN Document Server

    Nazarie, K

    1999-01-01

    Tehran Research Reactor , one can produce approximately 7 Ci of sup 1 sup 3 sup 1 I for medical purposes. By attention to the sup 1 sup 3 sup 1 I consumption rate in Iran, it is found this amount of sup 1 sup 3 sup 1 I will be enough for our country's demands. On the other hand, by installation of this new method we can produce other very useful radionuclides such as sup 9 sup 9 Mo and sup 1 sup 3 sup 3 Xe in one bath irradiation in the unique production line. sup 1 sup 3 sup 1 I is one of most widely used radionuclide in medical diagnosis and therapy especially for thyroid gland. This is mainly because of its unique nuclear, physical and chemical properties comparing with other radionuclides. In this thesis carrier free sup 1 sup 3 sup 1 I has been separated from natural uranium fission products in the bench scale (mu Ci) and then, sup 1 sup 3 sup 1 I separation and purification systems designed for large scale. Radionuclide, radiochemical and chemical purity of product are compatible with international phar...

  6. Uranium(IV) adsorption by natural organic matter in anoxic sediments

    Energy Technology Data Exchange (ETDEWEB)

    Bone, Sharon E.; Dynes, James J.; Cliff, John; Bargar, John R.

    2017-01-09

    Uranium is an important fuel source and a global environmental contaminant. It accumulates in the tetravalent state, U(IV), in anoxic sediments, including ore deposits, marine basins, and contaminated aquifers. However, very little is known about the speciation of U(IV) in low temperature geochemical environments, inhibiting the development of a conceptual model of U behavior. Until recently, U(IV) was assumed to exist predominantly as the sparingly soluble mineral uraninite (UO2) in anoxic sediments; yet studies now show that UO2 is not often dominant in these environments. However, a model of U(IV) speciation under environmentally relevant conditions has not yet been developed. Here we show that complexes of U(IV) adsorb on organic carbon and organic carbon-coated clays in an organic-rich natural substrate under field-relevant conditions. Whereas previous research assumed that the U(IV) product depended on the reduction pathway, our results demonstrate that UO2 formation can be inhibited simply by decreasing the U:solid ratio. Thus, it is the number and type of surface ligands that controls U(IV) speciation subsequent to U(VI) reduction. Projections of U transport and bioavailability, and thus its threat to human and ecosystem health, must consider retention of U(IV) ions within the local sediment environment.

  7. Contribution for the derivation of a soil screening value (SSV for uranium, using a natural reference soil.

    Directory of Open Access Journals (Sweden)

    Ana Luisa Caetano

    Full Text Available In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV. However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC20 and EC50 values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and <134.5 mg U Kg, respectively. Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC50 values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg(1. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC value of 15.5 mg kg-1dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1.

  8. Conceptual design study on very small long-life gas cooled fast reactor using metallic natural Uranium-Zr as fuel cycle input

    Energy Technology Data Exchange (ETDEWEB)

    Monado, Fiber, E-mail: fiber.monado@gmail.com [Nuclear Physics and Biophysics Research Group, Dept. of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung, Indonesia and Dept. of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University (Indonesia); Ariani, Menik [Dept. of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University (Indonesia); Su' ud, Zaki; Waris, Abdul; Basar, Khairul; Permana, Sidik [Nuclear Physics and Biophysics Research Group, Dept. of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung (Indonesia); Aziz, Ferhat [National Nuclear Energy Agency of Indonesia (BATAN) (Indonesia); Sekimoto, Hiroshi [CRINES, Tokyo Institute of Technology, O-okoyama, Meguro-ku, Tokyo 152-8550 (Japan)

    2014-02-12

    A conceptual design study of very small 350 MWth Gas-cooled Fast Reactors with Helium coolant has been performed. In this study Modified CANDLE burn-up scheme was implemented to create small and long life fast reactors with natural Uranium as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. The core with metallic fuel based was subdivided into 10 regions with the same volume. The fresh Natural Uranium is initially put in region-1, after one cycle of 10 years of burn-up it is shifted to region-2 and the each region-1 is filled by fresh Natural Uranium fuel. This concept is basically applied to all axial regions. The reactor discharge burn-up is 31.8% HM. From the neutronic point of view, this design is in compliance with good performance.

  9. Conceptual design study on very small long-life gas cooled fast reactor using metallic natural Uranium-Zr as fuel cycle input

    Science.gov (United States)

    Monado, Fiber; Ariani, Menik; Su'ud, Zaki; Waris, Abdul; Basar, Khairul; Aziz, Ferhat; Permana, Sidik; Sekimoto, Hiroshi

    2014-02-01

    A conceptual design study of very small 350 MWth Gas-cooled Fast Reactors with Helium coolant has been performed. In this study Modified CANDLE burn-up scheme was implemented to create small and long life fast reactors with natural Uranium as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. The core with metallic fuel based was subdivided into 10 regions with the same volume. The fresh Natural Uranium is initially put in region-1, after one cycle of 10 years of burn-up it is shifted to region-2 and the each region-1 is filled by fresh Natural Uranium fuel. This concept is basically applied to all axial regions. The reactor discharge burn-up is 31.8% HM. From the neutronic point of view, this design is in compliance with good performance.

  10. Preliminary Design Study of Medium Sized Gas Cooled Fast Reactor with Natural Uranium as Fuel Cycle Input

    Science.gov (United States)

    Meriyanti, Su'ud, Zaki; Rijal, K.; Zuhair, Ferhat, A.; Sekimoto, H.

    2010-06-01

    In this study a fesibility design study of medium sized (1000 MWt) gas cooled fast reactors which can utilize natural uranium as fuel cycle input has been conducted. Gas Cooled Fast Reactor (GFR) is among six types of Generation IV Nuclear Power Plants. GFR with its hard neuron spectrum is superior for closed fuel cycle, and its ability to be operated in high temperature (850° C) makes various options of utilizations become possible. To obtain the capability of consuming natural uranium as fuel cycle input, modified CANDLE burn-up scheme[1-6] is adopted this GFR system by dividing the core into 10 parts of equal volume axially. Due to the limitation of thermal hydraulic aspects, the average power density of the proposed design is selected about 70 W/cc. As an optimization results, a design of 1000 MWt reactors which can be operated 10 years without refueling and fuel shuffling and just need natural uranium as fuel cycle input is discussed. The average discharge burn-up is about 280 GWd/ton HM. Enough margin for criticallity was obtained for this reactor.

  11. [Content of natural uranium in the lichens and distribution of forms in the soil at the coastal area of Lakes Itkul and Sinara of Chelyabinsk region].

    Science.gov (United States)

    Polyudina, A L; Deryagin, V V; Levina, S G

    2014-01-01

    The distribution of natural uranium in soils superaquatic and transeluvial positions of the coastal landscape of lakes Itkul and Sinara, and liches on this site.The necessity of analysis of the content item in accordance with its form of occurrence in the natural environment. The peculiarities of the migration, accumulation and distribution of uranium in soils of the mountain areas of the watersheds of lakes Itkul and Sinara are found. Identified of specificity species lichens on the content of uranium in the substrate.

  12. Manhattan Project Technical Series The Chemistry of Uranium (I) Chapters 1-10

    Energy Technology Data Exchange (ETDEWEB)

    Rabinowitch, E. I. [Argonne National Laboratory (ANL), Argonne, IL (United States); Katz, J. J. [Argonne National Laboratory (ANL), Argonne, IL (United States)

    1946-09-30

    This constitutes Chapters 1 through 10. inclusive, of The Survey Volume on Uranium Chemistry prepared for the Manhattan Project Technical Series. Chapters are titled: Nuclear Properties of Uranium; Properties of the Uranium Atom; Uranium in Nature; Extraction of Uranium from Ores and Preparation of Uranium Metal; Physical Properties of Uranium Metal; Chemical Properties of Uranium Metal; Intermetallic Compounds and Alloy systems of Uranium; the Uranium-Hydrogen System; Uranium Borides, Carbides, and Silicides; Uranium Nitrides, Phosphides, Arsenides, and Antimonides.

  13. The effect of pH and natural microbial phosphatase activity on the speciation of uranium in subsurface soils

    Science.gov (United States)

    Beazley, Melanie J.; Martinez, Robert J.; Webb, Samuel M.; Sobecky, Patricia A.; Taillefert, Martial

    2011-10-01

    The biomineralization of U(VI) phosphate as a result of microbial phosphatase activity is a promising new bioremediation approach to immobilize uranium in both aerobic and anaerobic conditions. In contrast to reduced uranium minerals such as uraninite, uranium phosphate precipitates are not susceptible to changes in oxidation conditions and may represent a long-term sink for uranium in contaminated environments. So far, the biomineralization of U(VI) phosphate has been demonstrated with pure cultures only. In this study, two uranium contaminated soils from the Department of Energy Oak Ridge Field Research Center (ORFRC) were amended with glycerol phosphate as model organophosphate source in small flow-through columns under aerobic conditions to determine whether natural phosphatase activity of indigenous soil bacteria was able to promote the precipitation of uranium(VI) at pH 5.5 and 7.0. High concentrations of phosphate (1-3 mM) were detected in the effluent of these columns at both pH compared to control columns amended with U(VI) only, suggesting that phosphatase-liberating microorganisms were readily stimulated by the organophosphate substrate. Net phosphate production rates were higher in the low pH soil (0.73 ± 0.17 mM d -1) compared to the circumneutral pH soil (0.43 ± 0.31 mM d -1), suggesting that non-specific acid phosphatase activity was expressed constitutively in these soils. A sequential solid-phase extraction scheme and X-ray absorption spectroscopy measurements were combined to demonstrate that U(VI) was primarily precipitated as uranyl phosphate minerals at low pH, whereas it was mainly adsorbed to iron oxides and partially precipitated as uranyl phosphate at circumneutral pH. These findings suggest that, in the presence of organophosphates, microbial phosphatase activity can contribute to uranium immobilization in both low and circumneutral pH soils through the formation of stable uranyl phosphate minerals.

  14. Simultaneous determination of Ra-226, natural uranium and natural thorium by gamma-ray spectrometry INa(Ti), in solid samples.; Determinacion de U (Natural), Th (Natural) y Ra-226 en diversos materiales, mediante espectrometria con INa (TI)

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, S.; Navarro, T.; Alvarez, A.

    1991-07-01

    A method has been developed to determine activities of Ra-226, natural uranium and natural thorium by gamma-ray spectrometry. The measurement system has been calibrated using standards specially prepared at the laboratory. It is necessary to assume secular equilibrium in the samples, between Ra-226 and Th-232 and its daughters nuclides, and between U-238 and its immediate daughter Th-234, as the photo peaks measured are those of the daughters. The results obtained indicate that this method can of ter replace the radiochemical techniques used to measure activities in this type of sample. The method has been successfully used to determine these natural isotopes in samples from uranium mills. (Author) 9 refs.

  15. Uranium industry annual 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    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.

  16. The Non-Ergodic Nature of Internal Conversion

    DEFF Research Database (Denmark)

    Sølling, Theis I.; Kuhlman, Thomas Scheby; Stephansen, Anne B.

    2014-01-01

    as a tool to accomplish biomolecular stability. Herein, the discussion on nonstatistical internal conversion in DNA as a mechanism to eliminate Electronic excitation energy is extended to include molecules with an SS bond as a model of the disulfide bridge in peptides. All of these examples are summed up...... in Kasha’s rule. For systems with multiple degrees of freedom it will be possible to locate an appropriate motion somewhere in phase space that will take the wavepacket to the coupling region and facilitate an ultrafast transition to S1. Once at S1, the momentum of the wavepacket is lost and the only...

  17. Tetra- and hexavalent uranium forms bidentate-mononuclear complexes with particulate organic matter in a naturally uranium-enriched peatland

    DEFF Research Database (Denmark)

    Mikutta, Christian; Langner, Peggy; Bargar, John R.

    2016-01-01

    of bidentate-mononuclear U(IV/VI) complexes with carboxyl groups. We neither found evidence for U shells at ∼3.9 Å, indicative of mineral-associated U or multinuclear U(IV) species, nor for a substantial P/Fe coordination of U. Our data indicates that U(IV/VI) complexation by natural organic matter prevents...

  18. UNL Based Bangla Natural Text Conversion - Predicate Preserving Parser Approach

    CERN Document Server

    Ali, Md Nawab Yousuf; Allayear, Shaikh Muhammad

    2012-01-01

    Universal Networking Language (UNL) is a declarative formal language that is used to represent semantic data extracted from natural language texts. This paper presents a novel approach to converting Bangla natural language text into UNL using a method known as Predicate Preserving Parser (PPP) technique. PPP performs morphological, syntactic and semantic, and lexical analysis of text synchronously. This analysis produces a semantic-net like structure represented using UNL. We demonstrate how Bangla texts are analyzed following the PPP technique to produce UNL documents which can then be translated into any other suitable natural language facilitating the opportunity to develop a universal language translation method via UNL.

  19. A GIS-based Model for Natural Gas Data Conversion

    Science.gov (United States)

    Bitik, E.; Seker, D. Z.; Denli, H. H.

    2014-12-01

    In Turkey gas utility sector has undergone major changes in terms of increased competition between gas providers, efforts in improving services, and applying new technological solutions. This paper discusses the challenges met by gas companies to switch from long workflows of gas distribution, sales and maintenance into IT driven efficient management of complex information both spatially and non-spatially. The aim of this study is migration of all gas data and information into a GIS environment in order to manage and operate all infrastructure investments with a Utility Management System. All data conversion model for migration was designed and tested during the study. A flowchart is formed to transfer the old data layers to the new structure based on geodatabase.

  20. On the mixed nature of cerium conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Botana, F.J.; Aballe, A.; Bethencourt, M.; Cano, M.J. [Cadiz Univ. (Spain). Dept. de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica; Marcos, M. [Cadiz Univ. (Spain). Dept. de Ingenieria Mecanica y Diseno Industrial

    2002-03-01

    Alternative pretreatments are currently under development in order to avoid the environmental impact produced by using surface finishing processes based on chromates. Some of the environmentally friendly alternatives proposed involve the use of lanthanide based compounds. In this study, conversion coatings on AA5083 (Al-Mg) samples developed using full immersion pretreatments in 500 ppm CeCl{sub 3} aqueous solutions have been investigated. Their microscopic and compositional features have been analyzed using SEM images and EDS spectra. From this analysis it has been determined that this layer over the surface of the samples is of a heterogeneous composition. This coating is formed by an alumina coating covering the aluminum matrix and dispersed cerium-rich islands deposited over the cathodic sites of the alloy. A characterization methodology is proposed based on the utilization of different electrochemical techniques, such as open circuit potential monitoring (OCP), linear polarization (LP) and electrochemical impedance spectroscopy (EIS). (orig.)

  1. Biological assessment of the effects of construction and operation of a depleted uranium hexafluoride conversion facility at the Paducah, Kentucky, site.

    Energy Technology Data Exchange (ETDEWEB)

    Van Lonkhuyzen, R.

    2005-09-09

    The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF{sub 6}) Management Program evaluated alternatives for managing its inventory of DUF{sub 6} and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF{sub 6} PEIS) in April 1999 (DOE 1999). The DUF{sub 6} inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF{sub 6} PEIS, DOE stated its decision to promptly convert the DUF6 inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF{sub 6} conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF{sub 6} cylinders stored at ETTP to the Portsmouth site for conversion. This biological assessment (BA) has been prepared by DOE, pursuant to the National Environmental Policy Act of 1969 (NEPA) and the Endangered Species Act of 1974, to evaluate potential impacts to federally listed species from the construction and operation of a conversion facility at the DOE Paducah site.

  2. Natural uranium and thorium isotopes in sediment cores off Malaysian ports

    Science.gov (United States)

    Yusoff, Abdul Hafidz; Sabuti, Asnor Azrin; Mohamed, Che Abd Rahim

    2015-06-01

    Sediment cores collected from three Malaysian marine ports, namely, Kota Kinabalu, Labuan and Klang were analyzed to determine the radioactivities of 234U, 238U, 230Th, 232Th and total organic carbon (TOC) content. The objectives of this study were to determine the factors that control the activity of uranium isotopes and identify the possible origin of uranium and thorium in these areas. The activities of 234U and 238U show high positive correlation with TOC at the middle of sediment core from Kota Kinabalu port. This result suggests that activity of uranium at Kota Kinabalu port was influenced by organic carbon. The 234U/238U value at the upper layer of Kota Kinabalu port was ≥1.14 while the ratio value at Labuan and Klang port was ≤ 1.14. These results suggest a reduction process occurred at Kota Kinabalu port where mobile U(VI) was converted to immobile U(IV) by organic carbon. Therefore, it can be concluded that the major input of uranium at Kota Kinabalu port is by sorptive uptake of authigenic uranium from the water column whereas the major inputs of uranium to Labuan and Klang port are of detrital origin. The ratio of 230Th/232Th was used to estimate the origin of thorium. Low ratio value (lt; 1.5) at Labuan and Klang ports support the suggestion that thorium from both areas were come from detrital input while the high ratio (> 1.5) of 230Th/232Th at Kota Kinabalu port suggest the anthropogenic input of 230Th to this area. The source of 230Th is probably from phosphate fertilizers used in the oil-palm cultivation in Kota Kinabalu that is adjacent to the Kota Kinabalu port.

  3. Final environmental statement related to the United Nuclear Corporation, Morton Ranch, Wyoming Uranium Mill (Converse County, Wyoming)

    Energy Technology Data Exchange (ETDEWEB)

    1979-02-01

    Impacts from Morton Ranch Uranium Mill will result in: alterations of up to 270 acres occupied by the mill facilities; increase in the existing background radiation levels; socioeconomic effects on Glenrock and Douglas, Wyoming. Solid waste material (tailings solids) from the mill will be deposited onsite in exhausted surface mine pits. Any license issued for the Morton Ranch mill will be subject to conditions for the protection of the environment.

  4. Feasiblity of collecting naturally leached rice straw for thermal conversion

    NARCIS (Netherlands)

    Bakker, R.R.; Jenkins, B.M.

    2003-01-01

    The practical application of field or natural leaching to rice straw was evaluated with the goal of improving biomass fuel value. Observations on three rice farms in the Sacramento Valley, California indicated that potassium, chlorine and total ash are leached from rice straw by rainfall regardless

  5. Radiometric Determination of Uranium in Natural Waters after Enrichment and Separation by Cation-Exchange and Liquid-Liquid Extraction

    CERN Document Server

    Pashalidis, I

    2003-01-01

    The alpha-radiometric determination of uranium after its pre-concentration from natural water samples using the cation-exchange resin Chelex-100, its selective extraction by tributylphosphate and electrodeposition on stainless steel discs is reported. The validity of the separation procedure and the chemical recoveries were checked by addition of uranium standard solution as well as by tracing with U-232. The average uranium yield was determined to be (97 +- 2) % for the cation-exchange, (95 +- 2) % for the liquid-liquid extraction, and more than 99% for the electrodeposition. Employing high-resolution alpha-spectroscopy, the measured activity of the U-238 and U-234 radioisotopes was found to be of similar magnitude; i.e. ~7 mBq/L and ~35 mBq/L for ground- and seawater samples, respectively. The energy resolution (FWHM) of the alpha-peaks was 22 keV, while the Minimum Detectable Activity (MDA) was estimated to be 1 mBq/L (at the 95% confidence limit).

  6. Sonochemical precipitation of amorphous uranium phosphates from trialkyl phosphate solutions and their thermal conversion to UP2O7.

    Science.gov (United States)

    Doroshenko, Iaroslav; Zurkova, Jana; Moravec, Zdenek; Bezdicka, Petr; Pinkas, Jiri

    2015-09-01

    Insoluble amorphous precipitates containing uranyl and phosphate ions are obtained by sonication of solutions of three uranyl precursors, UO2(X)2, X=NO3, CH3COO, CH3C(O)CHC(O)CH3 (acetylacetonate, acac), in triesters of phosphoric acid, OP(OR)3, R=Me (trimethyl phosphate, TMP), Et (triethyl phosphate, TEP). TMP and TEP are used as high-boiling solvents and they serve also as a source of phosphate anions. Sonolysis experiments were carried out under flow of Ar at 40°C on a Sonics and Materials VXC 500W system (f=20 kHz, Pac=0.49 W cm(-3)). Powder X-ray diffraction (PXRD) reveals amorphous character of all obtained precipitates. The presence of uranyl and phosphate is evidenced by IR spectroscopy and ICP-OES analysis reveals the content of both U (38.6-43.4 wt%) and P (11.0-13.6 wt%). The thermal behavior of the substances was studied by TG/DSC analysis, which shows weight losses in the range of 19.21-24.08%. On heating the amorphous precipitates to 1000°C, crystalline uranium diphosphate UP2O7 is obtained in all cases as the only crystalline phase. Uranyl(VI) is reduced during thermolysis to U(IV) as there is no characteristic vibration of UO2(2+) in the IR spectra of solid UP2O7 products. The ICP-OES analysis of U and P content in precipitates allowed us to calculate the efficiency of precipitation of uranium from mother liquor and to compare it with the efficiency calculated from the data received by the PXRD and TG/DSC analyses. The efficiency of the uranium removal attained by our sonoprecipitation procedure was typically 30-35%. These sonochemical precipitation reactions providing insoluble uranium phosphates may be potentially interesting models for the description of behavior of uranium-containing waste or reprocessing streams.

  7. Conversion of individual natural gas to district heating

    DEFF Research Database (Denmark)

    Möller, Bernd; Lund, Henrik

    2010-01-01

    Replacing individual natural gas heating with district heating based to increasing shares of renewable energy sources may further reduce CO2-emissions in the Danish Building mass, while increasing flexibility of the energy system to accommodate significantly larger amounts of variable renewable...... energy production. The present paper describes a geographical study of the potential to expand district heating into areas supplied with natural gas. The study uses a highly detailed spatial database of the built environment, its current and potential future energy demand, its supply technologies and its...... location relative to energy infrastructure. First, using a spatially explicit economic model, the study calculates the potentials and costs of connection to expanded district heating networks by supply technology. Then a comprehensive energy systems analysis is carried out to model how the new district...

  8. Floodplain/wetland assessment of the effects of construction and operation ofa depleted uranium hexafluoride conversion facility at the Paducah, Kentucky,site.

    Energy Technology Data Exchange (ETDEWEB)

    Van Lonkhuyzen, R.

    2005-09-09

    The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF{sub 6}) Management Program evaluated alternatives for managing its inventory of DUF{sub 6} and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF{sub 6} PEIS) in April 1999 (DOE 1999). The DUF{sub 6} inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF{sub 6} PEIS, DOE stated its decision to promptly convert the DUF{sub 6} inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF{sub 6} conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF{sub 6} cylinders stored at ETTP to the Portsmouth site for conversion. This floodplain/wetland assessment has been prepared by DOE, pursuant to Executive Order 11988 (''Floodplain Management''), Executive Order 11990 (Protection of Wetlands), and DOE regulations for implementing these Executive Orders as set forth in Title 10, Part 1022, of the ''Code of Federal Regulations'' (10 CFR Part 1022 [''Compliance with Floodplain and Wetland Environmental Review Requirements'']), to evaluate potential impacts to floodplains and wetlands from the construction and operation of a conversion facility at the DOE Paducah site. Reconstruction of the bridge crossing Bayou Creek would occur within the Bayou Creek 100-year

  9. Determination of the isotopic composition of natural and slightly enriched uranium by alpha-spectrometry

    DEFF Research Database (Denmark)

    Kunzendorf, Helmar

    1968-01-01

    Determinations of the isotope contents of 238U, 235U and 234U in five uranium samples containing 0–5 at% 235U were carried out on the basis of a least-squares fit of the α-spectra from the samples, measured with a semiconductor detector, to the theoretically expected α-spectra. With a simple source...

  10. Spectroscopic Evidence of Uranium Immobilization in Acidic Wetlands by Natural Organic Matter and Plant Roots

    Science.gov (United States)

    Biogeochemistry of uranium in wetlands plays important roles in U immobilization in storage ponds of U mining and processing facilities but has not been well understood. The objective of this work was to study molecular mechanisms responsible for high U retention by Savannah Ri...

  11. Uranium: A Dentist's perspective

    OpenAIRE

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

    2012-01-01

    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 repla...

  12. Monte Carlo modeling and analyses of YALINA booster subcritical assembly, Part III : low enriched uranium conversion analyses.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, Y. (Nuclear Engineering Division)

    2011-05-12

    This study investigates the performance of the YALINA Booster subcritical assembly, located in Belarus, during operation with high (90%), medium (36%), and low (21%) enriched uranium fuels in the assembly's fast zone. The YALINA Booster is a zero-power, subcritical assembly driven by a conventional neutron generator. It was constructed for the purpose of investigating the static and dynamic neutronics properties of accelerator driven subcritical systems, and to serve as a fast neutron source for investigating the properties of nuclear reactions, in particular transmutation reactions involving minor-actinides. The first part of this study analyzes the assembly's performance with several fuel types. The MCNPX and MONK Monte Carlo codes were used to determine effective and source neutron multiplication factors, effective delayed neutron fraction, prompt neutron lifetime, neutron flux profiles and spectra, and neutron reaction rates produced from the use of three neutron sources: californium, deuterium-deuterium, and deuterium-tritium. In the latter two cases, the external neutron source operates in pulsed mode. The results discussed in the first part of this report show that the use of low enriched fuel in the fast zone of the assembly diminishes neutron multiplication. Therefore, the discussion in the second part of the report focuses on finding alternative fuel loading configurations that enhance neutron multiplication while using low enriched uranium fuel. It was found that arranging the interface absorber between the fast and the thermal zones in a circular rather than a square array is an effective method of operating the YALINA Booster subcritical assembly without downgrading neutron multiplication relative to the original value obtained with the use of the high enriched uranium fuels in the fast zone.

  13. Coordinated Operation of the Electricity and Natural Gas Systems with Bi-directional Energy Conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Zhang, Baohua; Fang, Jiakun

    2017-01-01

    A coordinated operation of the natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables. This work focuses on the unified optimal operation of the integrated natural gas and electricity system considering the network...

  14. Uranium and thorium behavior in groundwater of the natural spa area “Choygan mineral water” (East Tuva)

    Science.gov (United States)

    Kopylova, Y.; Guseva, N.; Shestakova, A.; Khvaschevskaya, A.; Arakchaa, K.

    2015-11-01

    The natural spa area “Choygan mineral waters”, a unique deposit of natural carbon dioxide mineral waters in Siberia, is located in the Eastern Sayan Mountains. There are 33 spring discharges in this area. Spring waters are mainly of HCO3-Na-Ca type. TDS varies from 300 mg/L to 2600 mg/L, the temperature ranges from 7 °C (in spring 33) to 39 °C (in spring 12), pH varies from 5.9 to 8.3, and the value of the oxidation-reduction potential is from -170 mV to 236 mV. All studied waters were divided into two groups according to their temperature and geochemical conditions: cold fresh water in oxidizing environment and warm slightly brackish water in reducing environment. The uranium concentration varies from 0.7 to 14 μg/l and the thorium concentration varies from 0.001 to 0.33 μg/l in the studied waters. The predominant uranium complexes are (UO2(CO3)3)4-, (UO2(CO3)2)2-, UO2CO3, (UO2(PO4)2)4- in the waters in oxidizing and reducing environments. It was found that acid-alkaline and oxidizing-reducing conditions were the determining factors for uranium behavior and speciation in the studied waters. The pH conditions are determining factors for thorium behavior and speciation in the studied waters. In slightly acidic water the predominant thorium species is negatively charge complex (ThCO3(OH)3)- (more than 95%).

  15. Radiochemical separation of thorium from 18O induced reaction with natural uranium

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A radiochemical procedure used to separate and purify trace concentra tion thorium produced in heavy ion reaction with uranium targets is presented. The procedure can rapidly yield thorium fraction suitable for gamma-ray spectroscopy studies. The resultant gamma-ray spectra showed that Th was isolated from a large number of elements produced in the reaction, and there were only a few contaminat ing activities of isotopes of Sc, Cd, In, etc. The decontamination factors for the main reaction products are given.

  16. Determination of Natural and Depleted Uranium in Urine at the ppt Level: An Interlaboratory Analytical Exercise

    Science.gov (United States)

    2002-10-01

    Q-MS) la spectrom6trie de masse A ionisation thermique (TIMS) et l’analyse par activation neutronique (NAA). Des rrsultats complets ont 6t6 obtenus de...laboratoire h6te. L’analyse par activation neutronique et TIMS enregistraient des concentrations d’uranium total qui diffrraient de celles du laboratoire...Q-MS) la spectromdtrie de masse h ionisation thermique (TIMS) et l’analyse par activation neutronique (NAA). RWsultats: Des ensembles de 12

  17. Natural arsenic and uranium accumulation and remobilization in different geological environments

    Energy Technology Data Exchange (ETDEWEB)

    Banning, Andre Wilhelm

    2012-03-05

    Despite the fact that both As and U represent geogenic trace elements potentially toxic to humans, little information is available on the development of their enrichments in German sediments and their potential impact on groundwater quality, let alone a systematic overview of the country's natural occurrences. This work aims at characterizing accumulation processes in aquifers actually or potentially affected by elevated concentrations of As and/or U, and their timings in geological history. The five selected study areas provide different geological and stratigraphical backgrounds. Identification of As and U sources, and structural derivation of their environmental reservoirs as well as remobilization mechanisms potentially resulting in trace element release to groundwater were assessed. Drinking water supply in Franconia/Northern Bavaria is dependent on groundwater extraction from terrestrial Upper Triassic sandstones where elevated concentrations of geogenic U and As exceeding German drinking water limitations were identified. Characterization of aquifer material in terms of geochemical and mineralogical composition, trace elements distribution on a microscale and their mineralogical fractionation and mobilization behaviour showed that uraniferous francolite/hematite inclusions within the aquifer sandstones (''active arkoses'') represent important sources for U and As in the study area. Francolite exhibits biologically, structurally and radiation-enhanced solubility; loss of both U and As during weathering was documented. Jurassic shallow marine Fe ores from the Upper Rhine Graben exhibit significant bulk As hosted in mainly goethite ooids slowly formed in times of condensed sedimentation. The study indicates that As accumulation was favoured over other potential contaminants, esp. heavy metals. Conditions for As accumulation varied during deposition, visible on a macro- (outcrop) as well as on a microscale (single Fe ooid). However, the

  18. CHEMICAL TOXICITY OF URANIUM

    Directory of Open Access Journals (Sweden)

    Sermin Cam

    2007-06-01

    Full Text Available Uranium, occurs naturally in the earth’s crust, is an alpha emitter radioactive element from the actinide group. For this reason, U-235 and U-238, are uranium isotopes with long half lives, have got radiological toxicity. But, for natural-isotopic-composition uranium (NatU, there is greater risk from chemical toxicity than radiological toxicity. When uranium is get into the body with anyway, also its chemical toxicity must be thought. [TAF Prev Med Bull 2007; 6(3.000: 215-220

  19. Distribution of natural radionuclides and uranium activity ratio in Gulf of Thailand sediments as base line data

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, S.K.; Hideki, A. [National Institute of Radiological Sciences (Japan); Kritsananuwat, R.; Fukushi, M. [Tokyo Metropolitan University (Japan); Chanyotha, S.; Pangza, K. [Chulalongkorn University (Thailand)

    2014-07-01

    This paper reports distribution of naturally occurring radionuclides and uranium activity ratio in marine sediments from selected coast, along the Gulf of Thailand to establish baseline data. Thailand has a plan to construct nuclear power plants (NPPs) as well as coal-fired thermal power plants to generate adequate and reliable electricity supply for rapid growth of industrialization. Therefore, it is important to focus not only on security and adequacy of power system but also on environmental protection and monitoring and risk assessment. To carry out environmental monitoring, baseline data plays a significant role. These data should be established and available before set up of mega projects that could impact the environment and health. Therefore, we have collected samples from five areas in the Gulf of Thailand, which are proposed as potential sites, to set up power plants by Thailand government. A total number of fifty-four marine sediment samples were collected. Gamma spectroscopy was used to determine the concentration of natural radionuclides e.g. {sup 226}Ra, {sup 228}Ac and {sup 40}K. Activity concentrations of {sup 226}Ra, {sup 228}Ac and {sup 40}K vary from 2.91-67.17 Bq/kg with an average of 26.64±14.57 Bq/kg, 4.42-109.17 Bq/kg with an average of 43.79±23.92 Bq/kg and 3.36-1004.56 Bq/kg with an average of 393.56±208.04 Bq/kg, respectively. The radiation hazard parameters including absorbed dose rate (D), annual effective dose equivalent (AEDE), radium equivalent activity (AGDE) and external hazard index (Hex) were calculated and compared with the international recommended values. We have noticed that sediments from two sites characterized by similar geological nature of landforms with a rocky coast have higher concentration of natural radionuclides. Concentration of uranium was determined using the inductively coupled plasma mass spectrometry (ICP-MS) and isotopic composition of {sup 234}U/{sup 238}U and {sup 235}U/{sup 238}U were determined using

  20. Theme--Achieving 2020. Goal 3: All Students Are Conversationally Literate in Agriculture, Food, Fiber, and Natural Resource Systems.

    Science.gov (United States)

    Trexler, Cary, Ed.

    2000-01-01

    Nine theme articles focus on the need for students to be conversationally literate about agriculture, food, fiber, and natural resources systems. Discusses the definition of conversational literacy, the human and institutional resources needed, and exemplary models for promoting literacy. (JOW)

  1. Contribution of analytical techniques coupled to the knowledge of the uranium speciation in natural conditions; Apports des techniques analytiques couplees a la connaissance de la speciation de l'uranium en conditions naturelles

    Energy Technology Data Exchange (ETDEWEB)

    Petit, J.

    2009-06-15

    To understand the transport mechanisms and the radionuclides behaviour in the bio-geosphere is necessary to evaluate healthy and environmental risks of nuclear industry. These mechanisms are monitored by radioelements speciation, namely the distribution between their different physico-chemical forms in the environment. From this perspective, this PhD thesis deals with uranium speciation in a natural background. A detailed summary of uranium biogeochemistry has been written, which enables to restrict the PhD issue to uranium complexation with oxalic acid, a hydrophilic organic acid with good binding properties, ubiquitous in soil waters. Analytical conditions have been established by means of speciation diagrams. The speciation diagrams building by means of literature stability constants has allowed to define the analytical conditions of complex formation. The chosen analytical technique is the hyphenation of a separative technique (liquid chromatography LC or capillary electrophoresis CE) with mass spectrometry (ICPMS). The studied complexes presence in the synthetic samples has been confirmed with UV/visible spectrophotometry. LC-ICPMS analyses have proved the lability of the uranyl-organic acid complexes, namely their tendency to dissociate during analysis, which prevents from studying uranium speciation. CE-ICPMS study of labile complexes from a metal-ligand system has been made possible by employing affinity capillary electrophoresis, which enables to determine stability constants and electrophoretic mobilities. This PhD thesis has allowed to compare the different mathematical treatments of binding isotherm and to take into account ionic strength and real ligand concentration. Affinity CE has been applied successfully to lanthanum-oxalate (model system) and uranium-oxalate systems. The obtained results have been applied to a real system (situated in Le Bouchet). This shows the contribution of the developed method to the modelling of uranium speciation. (author)

  2. Uranium mill tailings: nuclear waste and natural laboratory for geochemical and radioecological investigations

    Science.gov (United States)

    Landa, Edward R.

    2004-01-01

    Uranium mill tailings (UMT) are a high volume, low specific activity radioactive waste typically disposed in surface impoundments. This review focuses on research on UMT and related earth materials during the past decade relevant to the assessment of: (1) mineral hosts of radionuclides; (2) the use of soil analogs in predicting long-term fate of radionuclides; (3) microbial and diagenetic processes that may alter radionuclide mobility in the surficial environment; (4) waste-management technologies to limit radionuclide migration; and (5) the impact of UMT on biota.

  3. Uranium mill tailings: nuclear waste and natural laboratory for geochemical and radioecological investigations.

    Science.gov (United States)

    Landa, Edward R

    2004-01-01

    Uranium mill tailings (UMT) are a high volume, low specific activity radioactive waste typically disposed in surface impoundments. This review focuses on research on UMT and related earth materials during the past decade relevant to the assessment of: (1) mineral hosts of radionuclides; (2) the use of soil analogs in predicting long-term fate of radionuclides; (3) microbial and diagenetic processes that may alter radionuclide mobility in the surficial environment; (4) waste-management technologies to limit radionuclide migration; and (5) the impact of UMT on biota.

  4. Standard test method for uranium analysis in natural and waste water by X-ray fluorescence

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This test method applies for the determination of trace uranium content in waste water. It covers concentrations of U between 0.05 mg/L and 2 mg/L. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 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.

  5. Dioxins, furans, biphenyls, arsenic, thorium and uranium in natural and anthropogenic sources of phosphorus and calcium used in agriculture.

    Science.gov (United States)

    Avelar, A C; Ferreira, W M; Pemberthy, D; Abad, E; Amaral, M A

    2016-05-01

    The aim of this study was to assess the presence of dioxins, furans and biphenyls, and the inorganic contaminants such as arsenic (As), thorium (Th) and uranium (U) in three main products used in Agriculture in Brazil: feed grade dicalcium phosphate, calcined bovine bone meal and calcitic limestone. The first two are anthropogenic sources of phosphorus and calcium, while calcitic limestone is a natural unprocessed mineral. Regarding to dioxin-like substances, all samples analyzed exhibited dioxins (PCDD) and furans (PCDF) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations below limit of detection (LOD). In general, achieved is in accordance with regulation in Brazil where is established a maximum limit in limestone used in the citric pulp production (0.50pg WHO-TEQ g(-1)). In addition, reported data revealed very low levels for limestone in comparison with similar materials reported by European legislation. As result for toxic metals, achieved data were obtained using Instrumental Neutron Activation Analysis (INAA). On one hand, limestone sample exhibits the largest arsenic concentration. On another hand, dicalcium phosphate exhibited the largest uranium concentration, which represents a standard in animal nutrition. Therefore, it is phosphorus source in the animal feed industry can be a goal of concern in the feed field. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Neutron-induced transmutation reactions in 237Np, 238Pu, and 239Pu at the massive natural uranium spallation target

    Science.gov (United States)

    Zavorka, L.; Adam, J.; Baldin, A. A.; Caloun, P.; Chilap, V. V.; Furman, W. I.; Kadykov, M. G.; Khushvaktov, J.; Pronskikh, V. S.; Solnyshkin, A. A.; Sotnikov, V.; Stegailov, V. I.; Suchopar, M.; Tsoupko-Sitnikov, V. M.; Tyutyunnikov, S. I.; Voronko, V.; Vrzalova, J.

    2015-04-01

    Transmutation reactions in the 237Np, 238Pu, and 239Pu samples were investigated in the neutron field generated inside a massive (m = 512 kg) natural uranium spallation target. The uranium target assembly QUINTA was irradiated with the deuteron beams of kinetic energy 2, 4, and 8 GeV provided by the Nuclotron accelerator at the Joint Institute for Nuclear Research (JINR) in Dubna. The neutron-induced transmutation of the actinide samples was measured off-line by implementing methods of gamma-ray spectrometry with HPGe detectors. Results of measurement are expressed in the form of both the individual reaction rates and average fission transmutation rates. For the purpose of validation of radiation transport programs, the experimental results were compared with simulations of neutron production and distribution performed by the MCNPX 2.7 and MARS15 codes employing the INCL4-ABLA physics models and LAQGSM event generator, respectively. In general, a good agreement between the experimental and calculated reaction rates was found in the whole interval of provided beam energies.

  7. No fluorinated compounds in the uranium conversion process: risk analysis and proposition of pictograms; Os compostos nao fluorados nos processos da conversao do uranio: analise de riscos e proposicao de pictogramas

    Energy Technology Data Exchange (ETDEWEB)

    Jeronimo, Adroaldo Clovis; Oliveira, Wagner dos Santos, E-mail: acejota18@yahoo.com.br, E-mail: oliveira@feq.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Quimica; Aquino, Afonso Rodrigues de, E-mail: araquino@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-03-15

    The plants comprising the chemical conversion of uranium, which are part of the nuclear fuel cycle, present some risks, among others, because are associated with the non-fluorinated compounds handled in these processes. This study is the analysis of the risks associated with these compounds, i e, the non-fluorinated reactants and products, handled in different chemical processing plants, which include the production of uranium hexafluoride, while emphasizing the responsibilities and actions that fit to the chemical engineer with regard to minimizing risks during the various stages. The work is based on the experience gained during the development and mastery of the technology of production of uranium hexafluoride, the IPEN/ CNEN-SP, during the '80s, with the support of COPESP -Navy of Brazil. (author)

  8. Alpha and gamma spectrometry for natural radioactive nuclides around uranium mines and nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A.M.; Tome, F.V.; Bejarano, J.D.; Aparicio, A.G. (Universidad de Extremadura, Badajoz (Spain). Dept. de Fisica)

    1992-01-01

    Concentration of uranium and [sup 234]U/[sup 238]U and [sup 235]U/[sup 238]U activity ratios were studied in water samples taken in the neighbourhood of two uranium mines ('El Lobo' and 'El Pedregal', Badajoz, Spain), and around two nuclear power plants and their cooling reservoirs (the Central Nuclear de Almaraz, which is working today, and the Central Nuclear de Valdecaballeros, which is in the construction phase), using alpha spectrometry with semiconductor detectors. The Valdecaballeros data were taken to check for comparison with those of the Central Nuclear de Almaraz and with future values after the start of operation. Measurements were also made of all soluble gamma emitting nuclides using a shielded coaxial high purity germanium detector. The data suggest that the mechanisms responsible for the changes in the concentrations and in the [sup 234]U/[sup 238]U activity ratios in surface waters are principally dilution and leaching. (author).

  9. Assessing potential risks from exposure to natural uranium in well water

    Energy Technology Data Exchange (ETDEWEB)

    Hakonson-Hayes, A.C.; Fresquez, P.R. E-mail: fresquezp@lanl.gov; Whicker, F.W

    2002-07-01

    Over 50% of the wells in the Nambe region of northern New Mexico exceed the US Environmental Protection Agency's recommended drinking water standard of 20 {mu}g l{sup -1} for {sup 238}U; the highest in the area was measured at 1200 {mu}g U l{sup -1}. Uranium uptake was estimated in tomato (Lycopersicon esculentum), squash (Cucurbita pepo), lettuce (Lactuca scarriola), and radish (Raphanus sativus) irrigated with Nambe well water containing <1, 150, 500, and 1200 {mu}g U l{sup -1}. Plant uptake and human dose and toxicity associated with ingestion of water and produce and inhalation of irrigated soil related to gardening activities were evaluated. Uranium concentration in plants increased linearly with increasing U concentration in irrigation water, particularly in lettuce and radish. The estimated total committed effective dose for 70 years of maximum continuous exposure, via the three pathways to well water containing 1200 {mu}g U l{sup -1}, was 0.17 mSv with a corresponding kidney concentration of 0.8 {mu}g U g{sup -1} kidney.

  10. Natural uranium toxicology - evaluation of internal contamination in man; Toxicologie de l'uranium naturel - essai d'evaluation de la contamination interne chez l'homme

    Energy Technology Data Exchange (ETDEWEB)

    Chalabreysse, J. [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

    1968-07-01

    After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [French] Apres le rappel des caracteristiques physiques et des proprietes chimiques de l'uranium naturel pouvant avoir une influence sur sa toxicologie, l'etude detaillee de son metabolisme et de sa toxicite, puis l'application des normes professionnelles d'exposition au cas particulier de ce toxique, il est etabli, a partir des comptes rendus d'accidents et de l'experimentation humaine rapportes dans la litterature, une serie de formules obtenues par developpement mathematique theorique qui posent les principes de la surveillance et de la mise en evidence de la contamination interne par la recherche et le dosage de l'uranium dans les urines d'individus professionnellement exposes. Un essai d'evaluation de la contamination interne individuelle suivant les differents cas de contamination est effectue. Le formulaire propose permet de faire une premiere approximation et d'apprecier rapidement l'importance d

  11. Research and Development of Multiphysics Models in Support of the Conversion of the High Flux Isotope Reactor to Low Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bodey, Isaac T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Curtis, Franklin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Arimilli, Rao V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ekici, Kivanc [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Freels, James D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-11-01

    ABSTRACT The findings presented in this report are results of a five year effort lead by the RRD Division of the ORNL, which is focused on research and development toward the conversion of the High Flux Isotope Reactor (HFIR) fuel from high-enriched uranium (HEU) to low-enriched uranium (LEU). This report focuses on the tasks accomplished by the University of Tennessee Knoxville (UTK) team from the Department of Mechanical, Aerospace, and Biomedical Engineering (MABE) that provided expert support in multiphysics modeling of complex problems associated with the LEU conversion of the HFIR reactor. The COMSOL software was used as the main computational modeling tool, whereas Solidworks was also used in support of computer-aided-design (CAD) modeling of the proposed LEU fuel design. The UTK research has been governed by a statement of work (SOW), which was updated annually to clearly define the specific tasks reported herein. Ph.D. student Isaac T. Bodey has focused on heat transfer and fluid flow modeling issues and has been aided by his major professor Dr. Rao V. Arimilli. Ph.D. student Franklin G. Curtis has been focusing on modeling the fluid-structure interaction (FSI) phenomena caused by the mechanical forces acting on the fuel plates, which in turn affect the fluid flow in between the fuel plates, and ultimately the heat transfer, is also affected by the FSI changes. Franklin Curtis has been aided by his major professor Dr. Kivanc Ekici. M.Sc. student Adam R. Travis has focused two major areas of research: (1) on accurate CAD modeling of the proposed LEU plate design, and (2) reduction of the model complexity and dimensionality through interdimensional coupling of the fluid flow and heat transfer for the HFIR plate geometry. Adam Travis is also aided by his major professor, Dr. Kivanc Ekici. We must note that the UTK team, and particularly the graduate students, have been in very close collaboration with Dr. James D. Freels (ORNL technical monitor and mentor

  12. Research and Development of Multiphysics Models in Support of the Conversion of the High Flux Isotope Reactor to Low Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bodey, Isaac T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Curtis, Franklin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Arimilli, Rao V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ekici, Kivanc [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Freels, James D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-11-01

    The findings presented in this report are results of a five year effort led by the RRD Division of the ORNL, which is focused on research and development toward the conversion of the High Flux Isotope Reactor (HFIR) fuel from high-enriched uranium (HEU) to low-enriched uranium (LEU). This report focuses on the tasks accomplished by the University of Tennessee Knoxville (UTK) team from the Department of Mechanical, Aerospace, and Biomedical Engineering (MABE) that provided expert support in multiphysics modeling of complex problems associated with the LEU conversion of the HFIR reactor. The COMSOL software was used as the main computational modeling tool, whereas Solidworks was also used in support of computer-aided-design (CAD) modeling of the proposed LEU fuel design. The UTK research has been governed by a statement of work (SOW), which was updated annually to clearly define the specific tasks reported herein. Ph.D. student Isaac T. Bodey has focused on heat transfer and fluid flow modeling issues and has been aided by his major professor Dr. Rao V. Arimilli. Ph.D. student Franklin G. Curtis has been focusing on modeling the fluid-structure interaction (FSI) phenomena caused by the mechanical forces acting on the fuel plates, which in turn affect the fluid flow in between the fuel plates, and ultimately the heat transfer, is also affected by the FSI changes. Franklin Curtis has been aided by his major professor Dr. Kivanc Ekici. M.Sc. student Adam R. Travis has focused two major areas of research: (1) on accurate CAD modeling of the proposed LEU plate design, and (2) reduction of the model complexity and dimensionality through interdimensional coupling of the fluid flow and heat transfer for the HFIR plate geometry. Adam Travis is also aided by his major professor, Dr. Kivanc Ekici. We must note that the UTK team, and particularly the graduate students, have been in very close collaboration with Dr. James D. Freels (ORNL technical monitor and mentor) and have

  13. Hello, Who is Calling?: Can Words Reveal the Social Nature of Conversations?

    Science.gov (United States)

    Stark, Anthony; Shafran, Izhak; Kaye, Jeffrey

    2012-01-01

    This study aims to infer the social nature of conversations from their content automatically. To place this work in context, our motivation stems from the need to understand how social disengagement affects cognitive decline or depression among older adults. For this purpose, we collected a comprehensive and naturalistic corpus comprising of all the incoming and outgoing telephone calls from 10 subjects over the duration of a year. As a first step, we learned a binary classifier to filter out business related conversation, achieving an accuracy of about 85%. This classification task provides a convenient tool to probe the nature of telephone conversations. We evaluated the utility of openings and closing in differentiating personal calls, and find that empirical results on a large corpus do not support the hypotheses by Schegloff and Sacks that personal conversations are marked by unique closing structures. For classifying different types of social relationships such as family vs other, we investigated features related to language use (entropy), hand-crafted dictionary (LIWC) and topics learned using unsupervised latent Dirichlet models (LDA). Our results show that the posteriors over topics from LDA provide consistently higher accuracy (60-81%) compared to LIWC or language use features in distinguishing different types of conversations.

  14. Measurement methods and optimization of radiation protection: the case of internal exposure by inhalation to natural uranium compounds; Methodes de mesure et optimisation de la radioprotection: le cas des expositions internes par inhalation aux composes d'uranium naturel

    Energy Technology Data Exchange (ETDEWEB)

    Degrange, J.P. [Centre d' Etudes sur l' Evaluation de la Protection dans le domaine Nucleaire (CEPN), 92 - Fontenay-aux-Roses (France); Gibert, B. [Societe pour la Conversion de l' Uranium en Metal et Hexafluorure (COMURHEX), 11 - Narbonne (France)

    1998-07-01

    The aim of this presentation is to discuss the ability of different measurement methods (air sampling and biological examinations) to answer to demands in the particular case of internal exposure by inhalation to natural uranium compounds. The realism and the sensitivity of each method are studied, on the base of new dosimetric models of the ICRP. The ability of analysis of these methods in order to optimize radiation protection are then discussed. (N.C.)

  15. TECHNICAL REPORT ON TECHNOLOGICALLY ENHANCED NATURALLY OCCURRING RADIOACTIVE MATERIALS FROM URANIUM MINING, VOLUME II: INVESTIGATION OF POTENTIAL HEALTH, GEOGRAPHIC, AND ENVIRONMENTAL ISSUES OF ABANDONED URANIUM MINES

    Science.gov (United States)

    Volume II investigates the potential radiogenic risks from abandoned uranium mines and evaluates which may pose the greatest hazards to members of the public and to the environment. The intent of this report is to identify who may be most likely to be exposed to wastes at small a...

  16. Studying uranium migration in natural environment: experimental approach and geochemical modeling; Etude de la migration de l'uranium en milieu naturel: approche experimentale et modelisation geochimique

    Energy Technology Data Exchange (ETDEWEB)

    Phrommavanh, V.

    2008-10-15

    The present study deals with characterizing uranium migration in a limited zone of Le Bouchet site, a former uranium ore treatment facility, which is dismantled and the rehabilitation of which is under process. Some wastes are packed in a rehabilitated disposal nearby, called the Itteville site. In the framework of the monitoring of the deposit environment (air, water, sediment) set by prefectorial decrees, a piezometer (PZPK) located downstream to the latter, has shown total dissolved uranium peaks each winter since the 1990's. PZPK collects both the interstitial water of a calcareous peat formation, between the surface and 3 m, and an alluvial aquifer near 6 m of depth. Firstly, a hydrogeochemical characterization of the site has evidenced the uranium source term, which is present in the peat soil near 0.8 m, hence excluding any leaching from the waste disposal. Actually, a few microparticles of uranium oxide and mixed uranium-thorium oxide have been detected, but they do not represent the major part of the source term. Secondly, water chemistry of the peat soil water and PZPK has been monitored every two months from 2004 to 2007 in order to understand the reasons of the seasonal fluctuations of [U]tot.diss.. Completed with geochemical modeling and a bacterial identification by 16S rDNA sequence analysis, water chemistry data showed an important sulfate-reducing bacterial activity in summertime, leading to reducing conditions and therefore, a total dissolved uranium content limited by the low solubility of uraninite U{sup IV}O{sub 2}(s). In wintertime, the latter bacterial activity being minimal and the effective pluviometry more important, conditions are more oxidant, which favors U(VI), more soluble, notably as the Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) complex, evidenced by TRLFS. Finally, bacterial activity has been reproduced in laboratory in order to better characterize its impact on uranium solubility in the peat soil. Various parameters were tested

  17. Conversion of natural gas to C2 hydrocarbons through dielectric-barrier discharge plasma catalysis

    Institute of Scientific and Technical Information of China (English)

    王保伟; 许根慧

    2002-01-01

    The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 mL@min?1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons is 76%, and the total selectivity of C2 hydrocarbons and C3 hydrocarbons is nearly 100%. The conversion of methane increases with the increase of voltage and decreases with the flow of methane increase; the selectivity of C2 hydrocarbons decreases with the increase of voltage and increases with the flow of methane increase. The selectivity of C2 hydrocarbons is improved with catalyst for conversion of natural gas to C2 hydrocarbons in plasma field. Methane molecule collision with radicals is mainly responsible for product formation.

  18. Ancient natural uranium oxide as analog of spent fuel: Contribution to assessing the impact of helium production on long term evolution of UO{sub 2} matrix

    Energy Technology Data Exchange (ETDEWEB)

    Roudil, D.; Folch, B.; Jegou, C. [CEA centre de Marcoule BP 17171 30207 Bagnols sur Ceze cedex (France); Pik, R. [CNRS CRPG- 54506 Vandoeuvre les Nancy (France); Cuney, M. [Nancy Universite, G2R, CNRS, CREGU, BP 239, 54506, Vandoeuvre les Nancy (France); Gauthier-Lafaye, F. [ULP-EOST-CNRS/CGS- 1, rue Blessig - 67084 Strasbourg (France)

    2008-07-01

    Nuclear waste management in particular for spent fuel disposal option, needs an improvement of the knowledge concerning the fate of helium produced by actinide decrease and its impact on the physical and structural changes on the fuel matrix in a repository. An original alternative to {alpha} ageing simulation concerns the study and characterization of different old natural uranium oxides, with increasing age of crystallization. Since 2005, in the framework of a collaboration between Cea DEN/DTCD, CREGU and CNRS a methodology devoted to the study of helium behavior in this kind of samples has been developed and applied to three natural uranium oxides. Coupling results from gas release mass spectrometry measurements and from HR-TEM showed: -) high helium mobility at low temperature, -) an helium retention always lower than 0,9 at% in the uranium oxide grains, and -) high concentration of nanometer size helium bubbles, poorly pressurized and released at high temperature (above 1300 deg. C). Predictable evolutions of spent fuel matrix under self irradiation are presented within the domain of physical, chemical and structural analogy between natural uranium oxides and spent fuels. (authors)

  19. Chemical nature of phytic acid conversion coating on AZ61 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pan Fusheng [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China); Yang Xu, E-mail: yangxu2524@yahoo.com.cn [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China); Chemistry Department, Third Military Medical University, Chongqing, 400038 (China); Zhang Dingfei [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China)

    2009-07-30

    Phytic acid (PA) conversion coating on AZ61 magnesium alloy was prepared by the method of deposition. The influences of pH, time and PA concentration on the formation process, microstructure and properties of the conversion coating were investigated. Scanning electron microscopy (SEM) was used to observe the microstructure. The chemical nature of conversion coating was investigated by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques. The corrosion resistance was examined by means of potentiodynamic polarization method. The adhesive ability was tested by score experiments. The results showed that the growth and microstructure of the conversion coatings were all obviously affected by pH, time and PA concentration. In 0.5 mg/ml PA solution with a pH of 5, an optimization conversion coating formed after 20 min immersion time by deposition of PA on AZ61 magnesium alloy surface through chelating with Al{sup 3+}. It made the corrosion potential E{sub corr} of sample shifted positively about 171 mV than that of the untreated sample, and the adhesive ability reached to Grade 1 (in accordance with GB/T 9286).

  20. Chemical nature of phytic acid conversion coating on AZ61 magnesium alloy

    Science.gov (United States)

    Pan, Fusheng; Yang, Xu; Zhang, Dingfei

    2009-07-01

    Phytic acid (PA) conversion coating on AZ61 magnesium alloy was prepared by the method of deposition. The influences of pH, time and PA concentration on the formation process, microstructure and properties of the conversion coating were investigated. Scanning electron microscopy (SEM) was used to observe the microstructure. The chemical nature of conversion coating was investigated by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques. The corrosion resistance was examined by means of potentiodynamic polarization method. The adhesive ability was tested by score experiments. The results showed that the growth and microstructure of the conversion coatings were all obviously affected by pH, time and PA concentration. In 0.5 mg/ml PA solution with a pH of 5, an optimization conversion coating formed after 20 min immersion time by deposition of PA on AZ61 magnesium alloy surface through chelating with Al 3+. It made the corrosion potential Ecorr of sample shifted positively about 171 mV than that of the untreated sample, and the adhesive ability reached to Grade 1 (in accordance with GB/T 9286).

  1. Dioxins, furans, biphenyls, arsenic, thorium and uranium in natural and anthropogenic sources of phosphorus and calcium used in agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Avelar, A.C., E-mail: avelara@ufmg.br [Department of Animal Sciences, Veterinary School, Universidad de Federal de Minas Gerais Avenida Antonio Carlos, 6627 Campus UFMG, Belo Horizonte (Brazil); Ferreira, W.M. [Department of Animal Sciences, Veterinary School, Universidad de Federal de Minas Gerais Avenida Antonio Carlos, 6627 Campus UFMG, Belo Horizonte (Brazil); Pemberthy, D. [Spanish Council for Scientific Research (CSIC), Institute of Environmental Assessment and Water Research, C/ Jordi Girona 18-26, 08034 Barcelona (Spain); Universidad de Antioquia, Departamento de Ingeniería Química, Facultad de Ingeniería, Grupo Catálisis Ambiental, Calle 70 No. 52-2, Medellín (Colombia); Abad, E. [Spanish Council for Scientific Research (CSIC), Institute of Environmental Assessment and Water Research, C/ Jordi Girona 18-26, 08034 Barcelona (Spain); Amaral, M.A. [Department of Animal Sciences, Veterinary School, Universidad de Federal de Minas Gerais Avenida Antonio Carlos, 6627 Campus UFMG, Belo Horizonte (Brazil)

    2016-05-01

    The aim of this study was to assess the presence of dioxins, furans and biphenyls, and the inorganic contaminants such as arsenic (As), thorium (Th) and uranium (U) in three main products used in Agriculture in Brazil: feed grade dicalcium phosphate, calcined bovine bone meal and calcitic limestone. The first two are anthropogenic sources of phosphorus and calcium, while calcitic limestone is a natural unprocessed mineral. Regarding to dioxin-like substances, all samples analyzed exhibited dioxins (PCDD) and furans (PCDF) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations below limit of detection (LOD). In general, achieved is in accordance with regulation in Brazil where is established a maximum limit in limestone used in the citric pulp production (0.50 pg WHO-TEQ g{sup −1}). In addition, reported data revealed very low levels for limestone in comparison with similar materials reported by European legislation. As result for toxic metals, achieved data were obtained using Instrumental Neutron Activation Analysis (INAA). On one hand, limestone sample exhibits the largest arsenic concentration. On another hand, dicalcium phosphate exhibited the largest uranium concentration, which represents a standard in animal nutrition. Therefore, it is phosphorus source in the animal feed industry can be a goal of concern in the feed field. - Highlights: • PCDD/Fs dl- PCBs is not a matter since levels below the LOD in phosphate materials subject of study. • Significant accumulation of As and U in Limestone. Th was originally found in dicalcium phosphate. • High concentration of U in dicalcium phosphate suggests that a special attention should be paid.

  2. Migration behavior of naturally occurring radionuclides at the Nopal I uranium deposit, Chihuahua, Mexico

    Science.gov (United States)

    Prikryl, James D.; Pickett, David A.; Murphy, William M.; Pearcy, English C.

    1997-04-01

    Oxidation of pyrite at the Nopal I uranium deposit, Peña Blanca district, Chihuahua, Mexico has resulted in the formation of Fe-oxides/hydroxides. Anomalous U concentrations (i.e. several hundred to several thousand ppm) measured in goethite, hematite, and amorphous Fe-oxyhydroxides in a major fracture that crosscuts the deposit and the absence of U minerals in the fracture suggest that U was retained during secondary mineral growth or sorbed on mineral surfaces. Mobilization and transport of U away from the deposit is suggested by decreasing U concentrations in fracture-infilling materials and in goethite and hematite with distance from the deposit. Greater than unity {234U}/{238U} activity ratios measured in fracture-infilling materials indicate relatively recent ( < 1 Ma) U uptake from fluids that carried excess 234U. Systematic decreases in {234U}/{238U} activity ratios of fracture materials with distance from the deposit suggest a multistage mobilization process, such as remobilization of U from 234U-enriched infill minerals or differential or diminished transport of U-bearing solutions containing excess 234U.

  3. Biological assessment of the effects of construction and operation of adepleted uranium hexafluoride conversion facility at the Portsmouth, Ohio,site.

    Energy Technology Data Exchange (ETDEWEB)

    Van Lonkhuyzen, R.

    2005-09-09

    The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF{sub 6}) Management Program evaluated alternatives for managing its inventory of DUF{sub 6} and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF{sub 6} PEIS) in April 1999 (DOE 1999). The DUF{sub 6} inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF{sub 6} PEIS, DOE stated its decision to promptly convert the DUF{sub 6} inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF{sub 6} conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF{sub 6} cylinders stored at ETTP to the Portsmouth site for conversion. This biological assessment (BA) has been prepared by DOE, pursuant to the National Environmental Policy Act of 1969 and the Endangered Species Act of 1974, to evaluate potential impacts to federally listed species from the construction and operation of a conversion facility at the DOE Portsmouth site. The Indiana bat is known to occur in the area of the Portsmouth site and may potentially occur on the site during spring or summer. Evaluations of the Portsmouth site indicated that most of the site was found to have poor summer habitat for the Indiana bat because of the small size, isolation, and insufficient maturity of the few woodlands on the site. Potential summer habitat for the Indiana bat was

  4. Metal supported on natural zeolite as catalysts for conversion of ethanol to gasoline

    Directory of Open Access Journals (Sweden)

    Kristiani Anis

    2017-01-01

    Full Text Available A various of metal supported into natural zeolite was prepared via wet impregnation method. The transition metals impregnated are nickel, cobalt, copper and zinc. The catalytic properties both of physical and chemical properties were characterized by X-ray Diffraction (XRD, Thermo Gravimetri Analysis (TGA-Differential Scanning Calorimetry (DSC, Surface Area Analyzer-Porositymeter and also gravimetry method for acidity measurement following by the adsorption of organic bases. The results showed that different metals impregnated into natural zeolite affected physical and chemical properties, i.e. crystalinity, surface area, pore size, pore volume and acidity. Their catalytic activity was tested for conversion ethanol to gasoline and showed high conversion up to 80-90% with the aromatics as major product.

  5. Some economic aspects of natural uranium graphite gas reactor types. Present status and trends of costs in France; Quelques aspects economiques de la filiere uranium naturel - Graphite - gaz. Etat actuel et tendance des couts en France

    Energy Technology Data Exchange (ETDEWEB)

    Gaussens, J.; Tanguy, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Leo, B. [Electricite de France (EDF), 75 - Paris (France)

    1964-07-01

    The first part of this report defines the economic advantages of natural uranium fuels, which are as follows: the restricted number and relatively simple fabrication processes of the fuel elements, the low cost per kWh of the finished product and the reasonable capital investments involved in this type of fuel cycle as compared to that of enriched uranium. All these factors combine to reduce the arbitrary nature of cost estimates, which is particularly marked in the case of enriched uranium due to the complexity of its cycle and the uncertainties of plutonium prices). Finally, the wide availability of yellowcake, as opposed to the present day virtual monopoly of isotope separation, and the low cost of natural uranium stockpiling, offer appreciable guarantees in the way of security of supply and economic and political independence as compared with the use of enriched uranium. As far as overall capital investments are concerned, it is shown that, although graphite-gas reactor costs are higher than those of light water reactors in certain capacity ranges, the situation becomes far less clear when we start taking into account, in the interest of national independence, the cost of nuclear fuel production equipment in the case of each of these types of reactor. Finally, the marginal cost of the power capacity of a graphite-gas reactor is low and its technological limitations have receded (owing particularly to the use of prestressed concrete). It is a well known fact that the trend is now towards larger power station units, which means that the rentability of natural uranium graphite reactors as compared to other types of reactors will become more and more pronounced. The second section aims at presenting a realistic short and medium term view of the fuel, running, and investment costs of French natural uranium graphite gas, reactors. Finally, the economic goals which this type of reactor can reach in the very near future are given. It is thus shown that considerable

  6. Natural attenuation reactions at a uranium mill tailings site, western U.S.A.

    Science.gov (United States)

    Zhu, Chen; Anderson, Greg M; Burden, David S

    2002-01-01

    This paper presents a modeling analysis of the geochemical evolution of a contaminated sandy aquifer at a uranium mill tailings site in the western United States. The tailings pond contains fluids having a pH of 1.5 to 3.5 and high levels of As, Be, Cd, Cr, Pb, Mo, Ni, Se, 226Ra, 228Ra, 230Th, 238U, and 234U. Seepage of tailings fluids into the aquifer has formed a low-pH ground water plume. The reclamation plan is to install a low-permeability cover on the tailings pond to stop the seepage and allow the plume to be attenuated by reactions with the aquifer matrix and flushed by uncontaminated upgradient ground water. To evaluate this reclamation scenario, ground water and sediment core samples were analyzed along one flowpath. Speciation-solubility and mass-transfer modeling revealed two sets of chemical reactions for acid seepage and flushing, respectively. The current concentrations and distribution of ground water constituents can be interpreted as being controlled by stepwise pH-buffer reactions with calcite, amorphous aluminum hydroxide, and amorphous iron hydroxides. These buffer reactions divide the aquifer into zones of near-constant pH, separated by interface zones. For the flushing stage, it is predicted that reactions with surface-bound species will dominate the reaction paths, and more pore volumes are required to neutralize the plume than predicted by models that do not consider surface reactions. Direct mineralogical and surface analysis is needed to substantiate this assertion.

  7. Postextraction Separation, On-Board Storage, and Catalytic Conversion of Methane in Natural Gas: A Review.

    Science.gov (United States)

    Saha, Dipendu; Grappe, Hippolyte A; Chakraborty, Amlan; Orkoulas, Gerassimos

    2016-10-12

    In today's perspective, natural gas has gained considerable attention, due to its low emission, indigenous availability, and improvement in the extraction technology. Upon extraction, it undergoes several purification protocols including dehydration, sweetening, and inert rejection. Although purification is a commercially established technology, several drawbacks of the current process provide an essential impetus for developing newer separation protocols, most importantly, adsorption and membrane separation. This Review summarizes the needs of natural gas separation, gives an overview of the current technology, and provides a detailed discussion of the progress in research on separation and purification of natural gas including the benefits and drawbacks of each of the processes. The transportation sector is another growing sector of natural gas utilization, and it requires an efficient and safe on-board storage system. Compressed natural gas (CNG) and liquefied natural gas (LNG) are the most common forms in which natural gas can be stored. Adsorbed natural gas (ANG) is an alternate storage system of natural gas, which is advantageous as compared to CNG and LNG in terms of safety and also in terms of temperature and pressure requirements. This Review provides a detailed discussion on ANG along with computation predictions. The catalytic conversion of methane to different useful chemicals including syngas, methanol, formaldehyde, dimethyl ether, heavier hydrocarbons, aromatics, and hydrogen is also reviewed. Finally, direct utilization of methane onto fuel cells is also discussed.

  8. Assessment of the vertical distribution of natural radionuclides in a mineralized uranium area in south-west Spain.

    Science.gov (United States)

    Blanco Rodríguez, P; Vera Tomé, F; Lozano, J C

    2014-01-01

    Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation (LKB Quantulus 1220™) were used to determine the activity concentration of (238)U, (234)U, (230)Th, (226)Ra, (232)Th, and (210)Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were sampled from areas with different levels of influence from the installation and hence had different levels of contamination. The vertical profiles of the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. To determine the origin of these natural radionuclides the Enrichment Factor was used. Also, study of the activity ratios between radionuclides belonging to the same radioactive series allowed us to assess the different types of behaviors of the radionuclides involved. The vertical profiles for the radionuclide members of the (238)U series were different at each sampling point, depending on the level of influence of the installation. However, the profiles of each point were similar for the long-lived radionuclides of the (238)U series ((238)U, (234)U, (230)Th, and (226)Ra). Moreover, a major imbalance was observed between (210)Pb and (226)Ra in the surface layer, due to (222)Rn exhalation and the subsequent surface deposition of (210)Pb. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Conversion of associated natural gas to liquid hydrocarbons. Final report, June 1, 1995--January 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The original concept envisioned for the use of Fischer-Tropsch processing (FTP) of United States associated natural gas in this study was to provide a way of utilizing gas which could not be brought to market because a pipeline was not available or for which there was no local use. Conversion of gas by FTP could provide a means of utilizing offshore associated gas which would not require installation of a pipeline or re-injection. The premium quality F-T hydrocarbons produced by conversion of the gas can be transported in the same way as the crude oil or in combination (blended) with it, eliminating the need for a separate gas transport system. FTP will produce a synthetic crude oil, thus increasing the effective size of the resource. The two conventional approaches currently used in US territory for handling of natural gas associated with crude petroleum production are re-injection and pipelining. Conversion of natural gas to a liquid product which can be transported to shore by tanker can be accomplished by FTP to produce hydrocarbons, or by conversion to chemical products such as methanol or ammonia, or by cryogenic liquefaction (LNG). This study considers FTP and briefly compares it to methanol and LNG. The Energy International Corporation cobalt catalyst, ratio adjusted, slurry bubble column F-T process was used as the basis for the study and the comparisons. An offshore F-T plant can best be accommodated by an FPSO (Floating Production, Storage, Offloading vessel) based on a converted surplus tanker, such as have been frequently used around the world recently. Other structure types used in deep water (platforms) are more expensive and cannot handle the required load.

  10. Compressed natural gas and liquefied petroleum gas conversions: The National Renewable Energy Laboratory`s experience

    Energy Technology Data Exchange (ETDEWEB)

    Motta, R.C.; Kelly, K.J.; Warnock, W.W.

    1996-04-01

    The National Renewable Energy Laboratory (NREL) contracted with conversion companies in six states to convert approximately 900 light-duty Federal fleet vehicles to operate on compressed natural gas (CNG) or liquefied petroleum gas (LPG). The contracts were initiated in order to help the Federal government meet the vehicle acquisition requirements of the Energy Policy Act of 1992 (EPACT) during a period of limited original equipment manufacturer (OEM) model availability. Approximately 90% of all conversions were performed on compact of full-size vans and pickups, and 90% of the conversions were to bi-fuel operation. With a positive response from the fleet managers, this program helped the Federal government meet the vehicle acquisition requirements of EPACT for fiscal years 1993 and 1994, despite limited OEM model availability. The conversions also helped to establish the infrastructure needed to support further growth in the use of alternative fuel vehicles. In conclusion, the program has been successful in helping the Federal government meet the vehicle acquisition requirements of EPACT, establishing infrastructure, increasing the displacement of imported oil, and evaluating the emissions performance of converted vehicles. With the relatively widespread availability of OEM vehicles in the 1996 model year, the program is now being phased out.

  11. Conversion of natural gas to C2 hydrocarbons through dielectric-barrier discharge plasma catalysis

    Institute of Scientific and Technical Information of China (English)

    王保伟; 许根慧

    2002-01-01

    The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons i

  12. In vitro conversion of vinyl to formyl groups in naturally occurring chlorophylls.

    Science.gov (United States)

    Loughlin, Patrick C; Willows, Robert D; Chen, Min

    2014-08-14

    The chemical structural differences distinguishing chlorophylls in oxygenic photosynthetic organisms are either formyl substitution (chlorophyll b, d, and f) or the degree of unsaturation (8-vinyl chlorophyll a and b) of a side chain of the macrocycle compared with chlorophyll a. We conducted an investigation of the conversion of vinyl to formyl groups among naturally occurring chlorophylls. We demonstrated the in vitro oxidative cleavage of vinyl side groups to yield formyl groups through the aid of a thiol-containing compound in aqueous reaction mixture at room temperature. Heme is required as a catalyst in aqueous solution but is not required in methanolic reaction mixture. The conversion of vinyl- to formyl- groups is independent of their position on the macrocycle, as we observed oxidative cleavages of both 3-vinyl and 8-vinyl side chains to yield formyl groups. Three new chlorophyll derivatives were synthesised using 8-vinyl chlorophyll a as substrate: 8-vinyl chlorophyll d, [8-formyl]-chlorophyll a, and [3,8-diformyl]-chlorophyll a. The structural and spectral properties will provide a signature that may aid in identification of the novel chlorophyll derivatives in natural systems. The ease of conversion of vinyl- to formyl- in chlorophylls demonstrated here has implications regarding the biosynthetic mechanism of chlorophyll d in vivo.

  13. The Impact of Natural Hazards such as Turbulent Wind Gusts on the Wind Energy Conversion Process

    Science.gov (United States)

    Wächter, M.; Hölling, M.; Milan, P.; Morales, A.; Peinke, J.

    2012-12-01

    Wind turbines operate in the atmospheric boundary layer, where they are exposed to wind gusts and other types of natural hazards. As the response time of wind turbines is typically in the range of seconds, they are affected by the small scale intermittent properties of the turbulent wind. We show evidence that basic features which are known for small-scale homogeneous isotropic turbulence, and in particular the well-known intermittency problem, have an important impact on the wind energy conversion process. Intermittent statistics include high probabilities of extreme events which can be related to wind gusts and other types of natural hazards. As a summarizing result we find that atmospheric turbulence imposes its intermittent features on the complete wind energy conversion process. Intermittent turbulence features are not only present in atmospheric wind, but are also dominant in the loads on the turbine, i.e. rotor torque and thrust, and in the electrical power output signal. We conclude that profound knowledge of turbulent statistics and the application of suitable numerical as well as experimental methods are necessary to grasp these unique features and quantify their effects on all stages of wind energy conversion.

  14. Analytical strategies for uranium determination in natural water and industrial effluents samples; Estrategias analiticas para determinacao de uranio em amostras de aguas e efluentes industriais

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Juracir Silva

    2011-07-01

    The work was developed under the project 993/2007 - 'Development of analytical strategies for uranium determination in environmental and industrial samples - Environmental monitoring in the Caetite city, Bahia, Brazil' and made possible through a partnership established between Universidade Federal da Bahia and the Comissao Nacional de Energia Nuclear. Strategies were developed to uranium determination in natural water and effluents of uranium mine. The first one was a critical evaluation of the determination of uranium by inductively coupled plasma optical emission spectrometry (ICP OES) performed using factorial and Doehlert designs involving the factors: acid concentration, radio frequency power and nebuliser gas flow rate. Five emission lines were simultaneously studied (namely: 367.007, 385.464, 385.957, 386.592 and 409.013 nm), in the presence of HN0{sub 3}, H{sub 3}C{sub 2}00H or HCI. The determinations in HN0{sub 3} medium were the most sensitive. Among the factors studied, the gas flow rate was the most significant for the five emission lines. Calcium caused interference in the emission intensity for some lines and iron did not interfere (at least up to 10 mg L{sup -1}) in the five lines studied. The presence of 13 other elements did not affect the emission intensity of uranium for the lines chosen. The optimized method, using the line at 385.957 nm, allows the determination of uranium with limit of quantification of 30 {mu}g L{sup -1} and precision expressed as RSD lower than 2.2% for uranium concentrations of either 500 and 1000 {mu}g L{sup -1}. In second one, a highly sensitive flow-based procedure for uranium determination in natural waters is described. A 100-cm optical path flow cell based on a liquid-core waveguide (LCW) was exploited to increase sensitivity of the arsenazo 111 method, aiming to achieve the limits established by environmental regulations. The flow system was designed with solenoid micro-pumps in order to improve mixing and

  15. Coordinated Operation of the Electricity and Natural Gas Systems with Bi-directional Energy Conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Zhang, Baohua; Fang, Jiakun

    2017-01-01

    A coordinated operation of the natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables. This work focuses on the unified optimal operation of the integrated natural gas and electricity system considering the network...... constraints in both systems. An iterative method is proposed to deal with the nonlinearity in the proposed model. The models of the natural gas and power system are linearized in every iterative step. Simulation results demonstrate the effectiveness of the approach. Applicability of the proposed method...... is tested in the sample case. Finally, the effect of Power to Gas (P2G) on the daily economic dispatch is also investigated....

  16. Fluorinated compounds in the uranium conversion process: risk analysis and proposition of pictograms; Os compostos fluorados nos processos da conversao do uranio: analise de riscos e proposicao de pictogramas

    Energy Technology Data Exchange (ETDEWEB)

    Jeronimo, Adroaldo Clovis; Oliveira, Wagner dos Santos, E-mail: acejota18@yahoo.com.br, E-mail: oliveira@feq.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Quimica; Aquino, Afonso Rodrigues de, E-mail: araquino@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-03-15

    In the process of uranium hexafluoride production there are risks that must be taken into account since the time of completing the project chemist, in its conceptual stage, until to the stage of detailed design and are associated with the handling of chemicals, especially fluoride hydrogen and fluorine. This paper aims to address issues related to the prevention of risks related to industrial safety and health and the environment, considering the different stages of the uranium conversion. Take into account the safety warnings of the plant and, accordingly, make the proposition of pictograms adequate to alert operators of care to be taken during the proposition of pictograms adequate to alert operators of care to be taken during the conduct of these chemical processes. (author)

  17. Multi-component reactive transport modeling of natural attenuation of an acid groundwater plume at a uranium mill tailings site

    Science.gov (United States)

    Zhu, Chen; Hu, Fang Q.; Burden, David S.

    2001-11-01

    Natural attenuation of an acidic plume in the aquifer underneath a uranium mill tailings pond in Wyoming, USA was simulated using the multi-component reactive transport code PHREEQC. A one-dimensional model was constructed for the site and the model included advective-dispersive transport, aqueous speciation of 11 components, and precipitation-dissolution of six minerals. Transport simulation was performed for a reclamation scenario in which the source of acidic seepage will be terminated after 5 years and the plume will then be flushed by uncontaminated upgradient groundwater. Simulations show that successive pH buffer reactions with calcite, Al(OH) 3(a), and Fe(OH) 3(a) create distinct geochemical zones and most reactions occur at the boundaries of geochemical zones. The complex interplay of physical transport processes and chemical reactions produce multiple concentration waves. For SO 42- transport, the concentration waves are related to advection-dispersion, and gypsum precipitation and dissolution. Wave speeds from numerical simulations compare well to an analytical solution for wave propagation.

  18. How natural Forest Conversion Affects Insect Biodiversity in the Peruvian Amazon: Can Agroforestry Help?

    Directory of Open Access Journals (Sweden)

    Jitka Perry

    2016-04-01

    Full Text Available The Amazonian rainforest is a unique ecosystem that comprises habitat for thousands of animal species. Over the last decades, the ever-increasing human population has caused forest conversion to agricultural land with concomitant high biodiversity losses, mainly near a number of fast-growing cities in the Peruvian Amazon. In this research, we evaluated insect species richness and diversity in five ecosystems: natural forests, multistrata agroforests, cocoa agroforests, annual cropping monoculture and degraded grasslands. We determined the relationship between land use intensity and insect diversity changes. Collected insects were taxonomically determined to morphospecies and data evaluated using standardized biodiversity indices. The highest species richness and abundance were found in natural forests, followed by agroforestry systems. Conversely, monocultures and degraded grasslands were found to be biodiversity-poor ecosystems. Diversity indices were relatively high for all ecosystems assessed with decreasing values along the disturbance gradient. An increase in land use disturbance causes not only insect diversity decreases but also complete changes in species composition. As agroforests, especially those with cocoa, currently cover many hectares of tropical land and show a species composition similar to natural forest sites, we can consider them as biodiversity reservoirs for some of the rainforest insect species.

  19. The study of capability natural uranium as fuel cycle input for long life gas cooled fast reactors with helium as coolant

    Science.gov (United States)

    Ariani, Menik; Satya, Octavianus Cakra; Monado, Fiber; Su'ud, Zaki; Sekimoto, Hiroshi

    2016-03-01

    The objective of the present research is to assess the feasibility design of small long-life Gas Cooled Fast Reactor with helium as coolant. GCFR included in the Generation-IV reactor systems are being developed to provide sustainable energy resources that meet future energy demand in a reliable, safe, and proliferation-resistant manner. This reactor can be operated without enrichment and reprocessing forever, once it starts. To obtain the capability of consuming natural uranium as fuel cycle input modified CANDLE burn-up scheme was adopted in this system with different core design. This study has compared the core with three designs of core reactors with the same thermal power 600 MWth. The fuel composition each design was arranged by divided core into several parts of equal volume axially i.e. 6, 8 and 10 parts related to material burn-up history. The fresh natural uranium is initially put in region 1, after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions, i.e. shifted the core of the region (i) into region (i+1) region after the end of 10 years burn-up cycle. The calculation results shows that for the burn-up strategy on "Region-8" and "Region-10" core designs, after the reactors start-up the operation furthermore they only needs natural uranium supply to the next life operation until one period of refueling (10 years).

  20. The study of capability natural uranium as fuel cycle input for long life gas cooled fast reactors with helium as coolant

    Energy Technology Data Exchange (ETDEWEB)

    Ariani, Menik, E-mail: menikariani@gmail.com; Satya, Octavianus Cakra; Monado, Fiber [Department of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University, jl Palembang-Prabumulih km 32 Indralaya OganIlir, South of Sumatera (Indonesia); Su’ud, Zaki [Nuclear and Biophysics Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, jlGanesha 10, Bandung (Indonesia); Sekimoto, Hiroshi [CRINES, Tokyo Institute of Technology, 2-12-11N1-17 Ookayama, Meguro-Ku, Tokyo (Japan)

    2016-03-11

    The objective of the present research is to assess the feasibility design of small long-life Gas Cooled Fast Reactor with helium as coolant. GCFR included in the Generation-IV reactor systems are being developed to provide sustainable energy resources that meet future energy demand in a reliable, safe, and proliferation-resistant manner. This reactor can be operated without enrichment and reprocessing forever, once it starts. To obtain the capability of consuming natural uranium as fuel cycle input modified CANDLE burn-up scheme was adopted in this system with different core design. This study has compared the core with three designs of core reactors with the same thermal power 600 MWth. The fuel composition each design was arranged by divided core into several parts of equal volume axially i.e. 6, 8 and 10 parts related to material burn-up history. The fresh natural uranium is initially put in region 1, after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions, i.e. shifted the core of the region (i) into region (i+1) region after the end of 10 years burn-up cycle. The calculation results shows that for the burn-up strategy on “Region-8” and “Region-10” core designs, after the reactors start-up the operation furthermore they only needs natural uranium supply to the next life operation until one period of refueling (10 years).

  1. Conversion of Molybdenum-99 production process to low enriched uranium: Neutronic and thermal hydraulic analyses of HEU and LEU target plates for irradiation in Pakistan Research Reactor-1

    Science.gov (United States)

    Mushtaq, Ahmad; Iqbal, Masood; Bokhari, Ishtiaq Hussain; Mahmood, Tayyab; Muhammad, Atta

    2012-09-01

    Technetium-99m, the daughter product of Molybdenum-99 is the most widely needed radionuclide for diagnostic studies in Pakistan. Molybdenum-99 Production Facility has been established at PINSTECH. Highly enriched uranium (93% 235U) U/Al alloy targets have been irradiated in Pakistan Research Reactor-1 (PARR-1) for the generation of fission Mo-99, while basic dissolution technique is used for separation of Mo-99 from target matrix activity. In line with the international objective of minimizing and eventually eliminating the use of HEU in civil commerce, national and international efforts have been underway to shift the production of medical isotopes from HEU to LEU (LEU; uranium is needed. LEU aluminum uranium dispersion target has been developed, which may replace existing HEU aluminum/uranium alloy targets for production of 99Mo using basic dissolution technique. Neutronic and thermal hydraulic calculations were performed for safe irradiation of targets in the core of PARR-1.

  2. Silvicultural interpretation of natural vegetation dynamics in ageing Scots pine stands for their conversion into mixed broadleaved stands

    NARCIS (Netherlands)

    Kint, V.; Geudens, G.; Mohren, G.M.J.; Lust, N.

    2006-01-01

    In many West-European regions there is principal consensus on the conversion of homogeneous even-aged Scots pine plantations into mixed broadleaved stands. In recent years, interest is growing for conversion management in which managers try to maximise the use of natural processes by steering or

  3. Silvicultural interpretation of natural vegetation dynamics in ageing Scots pine stands for their conversion into mixed broadleaved stands

    NARCIS (Netherlands)

    Kint, V.; Geudens, G.; Mohren, G.M.J.; Lust, N.

    2006-01-01

    In many West-European regions there is principal consensus on the conversion of homogeneous even-aged Scots pine plantations into mixed broadleaved stands. In recent years, interest is growing for conversion management in which managers try to maximise the use of natural processes by steering or acc

  4. Conversion of a diesel engine to a spark ignition natural gas engine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    Requirements for alternatives to diesel-fueled vehicles are developing, particularly in urban centers not in compliance with mandated air quality standards. An operator of fleets of diesel- powered vehicles may be forced to either purchase new vehicles or equip some of the existing fleets with engines designed or modified to run on alternative fuels. In converting existing vehicles, the operator can either replace the existing engine or modify it to burn an alternative fuel. Work described in this report addresses the problem of modifying an existing diesel engine to operate on natural gas. Tecogen has developed a technique for converting turbocharged automotive diesel engines to operate as dedicated spark-ignition engines with natural gas fuel. The engine cycle is converted to a more-complete-expansion cycle in which the expansion ratio of the original engine is unchanged while the effective compression ratio is lowered, so that engine detonation is avoided. The converted natural gas engine, with an expansion ratio higher than in conventional spark- ignition natural gas engines, offers thermal efficiency at wide-open- throttle conditions comparable to its diesel counterpart. This allows field conversion of existing engines. Low exhaust emissions can be achieved when the engine is operated with precise control of the fuel air mixture at stoichiometry with a 3-way catalyst. A Navistar DTA- 466 diesel engine with an expansion ratio of 16.5 to 1 was converted in this way, modifying the cam profiles, increasing the turbocharger boost pressure, incorporating an aftercooler if not already present, and adding a spark-ignition system, natural gas fuel management system, throttle body for load control, and an electronic engine control system. The proof-of-concept engine achieved a power level comparable to that of the diesel engine without detonation. A conversion system was developed for the Navistar DT 466 engine. NOx emissions of 1.5 g/bhp-h have been obtained.

  5. Natural arsenic and uranium accumulation and remobilization in different geological environments

    OpenAIRE

    Banning, Andre

    2012-01-01

    Despite the fact that both As and U represent geogenic trace elements potentially toxic to humans, little information is available on the development of their enrichments in German sediments and their potential impact on groundwater quality, let alone a systematic overview of the country´s natural occurrences. This work aims at characterizing accumulation processes in aquifers actually or potentially affected by elevated concentrations of As and/or U, and their timings in geological history. ...

  6. Solid-phase extraction-spectrophotometric determination of uranium(VI) in natural waters

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Susan; Mohammadzadeh, Darush [Department of Chemistry, University of Birjand, Birjand (Iran); Yamini, Yadollah [Department of Chemistry, Tarbiat Moddars University, Tehran (Iran)

    2003-03-01

    A method for the extraction and determination of uranyl ion in natural waters using octadecyl bonded silica membrane disks modified with piroxicam and spectrophotometry with arsenazo(III) is proposed. The perconcentration step was studied with regard to experimental parameters such as amount of extractant, type and amount of eluent, pH, flow rates and tolerance limit of diverse ions on the recovery of uranyl ion. The limit of detection of the proposed method is 0.4 {mu}g L{sup -1} of uranyl. The method was applied to the recovery of uranyl from different water samples. (orig.)

  7. A Review of Temporal Aspects of Hand Gesture Analysis Applied to Discourse Analysis and Natural Conversation

    Directory of Open Access Journals (Sweden)

    Renata C. B. Madeo

    2013-08-01

    Full Text Available Lately, there has been an increasinginterest in hand gesture analysis systems. Recent works have employedpattern recognition techniques and have focused on the development of systems with more natural userinterfaces. These systems may use gestures to control interfaces or recognize sign language gestures, whichcan provide systems with multimodal interaction; or consist in multimodal tools to help psycholinguists tounderstand new aspects of discourse analysis and to automate laborious tasks.Gestures are characterizedby several aspects, mainly by movementsand sequence of postures. Since data referring to movementsorsequencescarry temporal information, this paper presents aliteraturereviewabouttemporal aspects ofhand gesture analysis, focusing on applications related to natural conversation and psycholinguisticanalysis, using Systematic Literature Review methodology. In our results, we organized works according totype of analysis, methods, highlighting the use of Machine Learning techniques, and applications.

  8. Bio-Photovoltaic Conversion Device Made from Chitosan Nanofibers and Varieties of Natural Pigments

    Directory of Open Access Journals (Sweden)

    Siriwat BOONCHAISRI

    2014-05-01

    Full Text Available In this study, the natural pigments anthocyanin, beta carotene, chlorophyll, and curcumin, extracted from red cabbage, carrot, water hyacinth and turmeric, respectively, were used as sensitized dyes in a Bio-photovoltaic Conversion Device (BPV, and the energy conversion efficiencies (h were compared. The photoelectrodes were designed to use various photoactive layers made of porous TiO2 or a new TiO2:nanofiber interface. The nanofibers were prepared by an electrospinning chitosan solution, a PVA solution (poly(vinylalcohol, and their mixture at different conditions. Analysis from a scanning electron microscope (SEM showed that the formation and the density of nanofibers increase with increasing amount of PVA. The highest h was observed in solar cells which used anthocyanin extracted from red cabbage. When considering the photoactive layers made of TiO2:nanofibers prepared from the mixture between 1.2 % chitosan in acetic acid and 8 % PVA in aqueous solution at the ratio of 1:1. w/w ([1.2Chitosan]+[8PVA], it raised the h up to 5.3 times higher than by the TiO2 alone. Therefore, the utilization of chitosan nanofibers together with the application of natural dyes has the potential to increase h of BPVs.doi:10.14456/WJST.2014.23

  9. The nature of arsenic in uranium mill tailings by X-ray absorption spectroscopy

    Science.gov (United States)

    Cutler, J. N.; Chen, N.; Jiang, D. T.; Demopoulos, G. P.; Jia, Y.; Rowson, J. W.

    2003-05-01

    In order to understand the evolving world of environmental issues, the ability to characterize and predict the stability and bioavailability of heavy métal contaminants in mine waste is becoming increasingly more important. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopies were used to characterize a series of synthetic and natural samples associated with mine tailings processing. XANES was shown to be excellent as a tool to rapidly differentiate oxidation states of arsenic within the samples. The EXAFS spectra provided information on the mineralogy of the precipitated raffinate and tailings and showed that these samples are composed of a mixture of amorphous ferric arsenates, adsorbed arsenates and a mixture of other poorly ordered arsenates.

  10. Geochemistry of uranium and thorium and natural radioactivity levels of the western Anatolian plutons, Turkey

    Science.gov (United States)

    Papadopoulos, Argyrios; Altunkaynak, Şafak; Koroneos, Antonios; Ünal, Alp; Kamaci, Ömer

    2017-01-01

    Seventy samples from major plutons (mainly granitic) of Western Anatolia (Turkey) have been analyzed by γ-ray spectrometry to determine the specific activities of 238U, 226Ra, 232Th and 40K (Bq/kg). Τhe natural radioactivity ranged up to 264 Bq/kg for 238U, 229.62 Bq/kg for 226Ra, up to 207.32 Bq/kg for 232Th and up to 2541.95 Bq/kg for 40K. Any possible relationship between the specific activities of 226Ra, 238U, 232Th and 40K and some characteristics of the studied samples (age, rock-type, colour, grain size, occurrence, chemical and mineralogical composition) was investigated. Age, major and trace element geochemistry, color, pluton location and mineralogical composition are likely to affect the concentrations of the measured radionuclides. The range of the Th/U ratio was large (0.003-11.374). The latter, along with 226Ra/238U radioactive secular disequilibrium, is also discussed and explained by magmatic processes during differentiation.

  11. Corrosion-resistant uranium

    Science.gov (United States)

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

    1981-10-21

    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.

  12. Occurrence of fungus Rhizopus sp in bioassays with Allium cepa germinated in the presence of uranium to study the effect of natural radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Magno N.; Oliveira, Andressa L.; Maffei, Eliane M.D.; Campos, Simara S., E-mail: simaracampos@gmail.com [Universidade Estadual do Sudoeste da Bahia (UESB), Vitoria da Conquista, BA (Brazil). Departamento de Ciencias Exatas e Tecnologicas; Gennari, Roseli F. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica. Departamento de Fisica Nuclear

    2015-07-01

    The demographic and global economic growth has promoted increasing power consumption. In this context, several studies point to nuclear energy as being promising to meet such demand. Although Brazil composes the seventh position in the world ranking of uranium reserves, the ore is still little explored in Brazil, considering its vast existing arsenal. On the one hand, despite nuclear energy has brought great benefits, technological and socio-economic development, it generates controversy about environmental contamination and risks to public health. Studies on this subject indicate that areas where uranium ore concentration is high, natural environmental radiation exposure levels are already higher than in other regions. The aim of this study is to observe the simple germination of the bio-indicator (Allium cepa), typically used to assess potential chromosomal aberrations, suffer any adverse effect caused by natural radiation uranium. The choice of this bio-indicator is based on its potential for evaluating the mutation caused by countless chemical compounds. Four treatments with three replicates were designed. In each treatment, 10 seeds of onion A. cepa without any pesticides were packed in the Petri dish lined with germination paper and room temperature (25°C) was kept until the root reaches approximately 1cm long. As a result, growth of the fungus Rhizopus sp was observed, in the experiments where uranium ore was added. It is important to mention according to the literature, this fungus can cause serious infections (and often fatal) in humans and animals, due to its high growth rate and also to their ability on surviving in relatively high temperatures. (author)

  13. The uranium in the environment; L'uranium dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The uranium is a natural element omnipresent in the environment, with a complex chemistry more and more understood. Many studies are always today devoted to this element to better improve the uranium behavior in the environment. To illustrate this knowledge and for the public information the CEA published this paper. It gathers in four chapters: historical aspects and properties of the uranium, the uranium in the environment and the impacts, the metrology of the uranium and its migration. (A.L.B.)

  14. Effectiveness of mineral soil to adsorb the natural occurring radioactive material (norm), uranium and thorium

    Energy Technology Data Exchange (ETDEWEB)

    Amir, Muhammad Nur Iman; Ismail, Nurul Izzatiafifi; Wood, Ab. Khalik, E-mail: khalik@salam.uitm.edu.my; Saat, Ahmad; Hamzah, Zaini [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2015-04-29

    A study has been performed on U-soil and Th-soil adsorption of three types of soil collected from Selangor State of Malaysia which are Saujana Putra, Bukit Changgang and Jenderam Hilir. In this study, natural radionuclide (U and Th) soil adsorption based on batch experiments with various initial concentrations of the radionuclide elements were carried out. Parameters that were set constant include pH at 5;amount of soil used was 5 g each, contact time was 24 hour and different initial concentration for each solution of U and Th which is 5 mg/L, 10 mg/L, 15 mg/L, 20 mg/L, 25 mg/L and 40 mg/L were used. The K{sub d} values for each type of soil were determined in this batch experiments which was based on US-EPA method, in order to estimate adsorption capacity of the soil.The K{sub d} values of Th found higher than Kd values of U for all of the soil samples, and the highest was found on the soil collected from Bukit Changgang. The soil clay content was one of factors to influence the adsorption of both U and Th from dilute initial solution. The U-soil and Th-soil adsorption process for all the soil samples studied are generally obeying unimolecular layer Langmuir isotherm model. From Langmuir isotherm, the maximum adsorption capacity for U was 0.393mg/g and for Th was 1.53 mg/g for the soil that was taken from Bukit Changgang. From the study, it suggested that the soil from Bukit Changgang applicable as potential enhanced barrier for site disposing waste containing U and Th.

  15. Assumptions and Criteria for Performing a Feasability Study of the Conversion of the High Flux Isotope Reactor Core to Use Low-Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Primm, R.T., III; Ellis, R.J.; Gehin, J.C.; Moses, D.L.; Binder, J.L.; Xoubi, N. (U. of Cincinnati)

    2006-02-01

    A computational study will be initiated during fiscal year 2006 to examine the feasibility of converting the High Flux Isotope Reactor from highly enriched uranium fuel to low-enriched uranium. The study will be limited to steady-state, nominal operation, reactor physics and thermal-hydraulic analyses of a uranium-molybdenum alloy that would be substituted for the current fuel powder--U{sub 3}O{sub 8} mixed with aluminum. The purposes of this document are to (1) define the scope of studies to be conducted, (2) define the methodologies to be used to conduct the studies, (3) define the assumptions that serve as input to the methodologies, (4) provide an efficient means for communication with the Department of Energy and American research reactor operators, and (5) expedite review and commentary by those parties.

  16. Chronic uranium exposure dose-dependently induces glutathione in rats without any nephrotoxicity.

    Science.gov (United States)

    Poisson, C; Stefani, J; Manens, L; Delissen, O; Suhard, D; Tessier, C; Dublineau, I; Guéguen, Y

    2014-10-01

    Uranium is a heavy metal naturally found in the earth's crust that can contaminate the general public population when ingested. The acute effect and notably the uranium nephrotoxicity are well known but knowledge about the effect of chronic uranium exposure is less clear. In a dose-response study we sought to determine if a chronic exposure to uranium is toxic to the kidneys and the liver, and what the anti-oxidative system plays in these effects. Rats were contaminated for 3 or 9 months by uranium in drinking water at different concentrations (0, 1, 40, 120, 400, or 600 mg/L). Uranium tissue content in the liver, kidneys, and bones was linear and proportional to uranium intake after 3 and 9 months of contamination; it reached 6 μg per gram of kidney tissues for the highest uranium level in drinking water. Nevertheless, no histological lesions of the kidney were observed, nor any modification of kidney biomarkers such as creatinine or KIM-1. After 9 months of contamination at and above the 120-mg/L concentration of uranium, lipid peroxidation levels decreased in plasma, liver, and kidneys. Glutathione concentration increased in the liver for the 600-mg/L group, in the kidney it increased dose dependently, up to 10-fold, after 9 months of contamination. Conversely, chronic uranium exposure irregularly modified gene expression of antioxidant enzymes and activities in the liver and kidneys. In conclusion, chronic uranium exposure did not induce nephrotoxic effects under our experimental conditions, but instead reinforced the antioxidant system, especially by increasing glutathione levels in the kidneys.

  17. Natural and anthropogenic enrichments of molybdenum, thorium, and uranium in a complete peat bog profile, Jura Mountains, Switzerland.

    Science.gov (United States)

    Krachler, Michael; Shotyk, William

    2004-05-01

    A core from an ombrotrophic Swiss bog representing 12 370 (14)C years of peat accumulation was evaluated as a possible archive of atmospheric deposition of Mo, Th and U. Calcium, Sr, and Ba were also determined to quantify weathering inputs, Mn to follow possible redox transformations, and Rb to identify plant uptake. Each of these elements was determined using ICP-MS, following digestion in a microwave heated autoclave using 3 ml HNO(3) and 0.1 ml HBF(4). Calcium and Sr clearly identify the thickness of the ombrotrophic zone because they are enriched in the minerogenic zone relative to the concentration of mineral matter. The concentration of Ba, however, is proportional to the concentration of mineral matter in all samples, and is not added to peat column by weathering reactions at the peat-sediment interface. The lowest element concentrations are found during the Holocene climate optimum (5320 to 8030 (14)C year BP) with the following natural background values (n= 18): Mo 0.08 +/- 0.02 microg g(-1), U 0.029 +/- 0.008 microg g(-1), Ba 5.2 +/- 2.6 microg g(-1), Th 0.070 +/- 0.022 microg g(-1) and Rb 0.63 +/- 0.09 microg g(-1). By far the highest concentrations of Ba, Mn, Rb and Th were found during the Younger Dryas cold climate event (10 590 (14)C year BP) when the flux of atmospheric soil dust was at its post-glacial maximum. Molybdenum and U are elevated in concentration throughout the minerogenic zone because of sediment weathering and this masks the atmospheric signal in samples older than ca. 8000 (14)C year BP (ca. 9000 calendar years). Enrichment factors (EF) calculated using Sc as a conservative, lithogenic element shows that minerogenic peats are enriched in Mo up to 18x and U 26x, relative to the natural "background" values. During the two millennia prior to industrialisation, the accumulation rate of atmospheric Mo averaged 0.23 +/- 0.13 microg m(-2) year(-1). With the onset of the Industrial Revolution, Mo accumulation rates rapidly and continuously

  18. Dye ingredients and energy conversion efficiency at natural dye sensitized solar cells

    Science.gov (United States)

    Özbay Karakuş, Mücella; Koca, İrfan; Er, Orhan; Çetin, Hidayet

    2017-04-01

    In this work, natural dyes extracted from the same genus but different species flowers were used as sensitizer in Dye Sensitized Solar Cell (DSSC). To clearly show dye ingredients effect on electrical characteristics, the same genus flowers were selected. The dye ingredients were analyzed by Gas Chromatography Mass Spectrometer (GC-MS). The dyes were modified by a procedure that includes refluxing in acetone. All results indicate a relationship between gallic acid quantity in dyes and solar cell efficiency. To gain further insight, the solar cell parameters were obtained by using the single-diode and double-diode models and they were compared to each other. It was observed that the applied process causes a decrease in series resistance. How the modification process and gallic acid affect energy conversion efficiency were argued in detail in the frame of results that were obtained from solar cell models.

  19. Study for engine conversion from gasoline to natural gas by using the two-zone combustion predictive model; Estudio de la conversion del motor de gasolina a gas natural mediante modelo de combustion predictivo de dos zonas

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Espinoza; Moreno, Jesus; Perez, Andres [Universidad de Oriente, Puerto la Cruz (Venezuela). Dept. de Mecanica; Baduy, Franklin [Universidad Central de Venezuela, Caracas (Venezuela). Dept. de Termoenergetica

    1995-07-01

    Great scale conversion of automation engines is a policy used by many countries as a strategy to save gasoline. Previous studies on the effects that this transformation can have over the engine performance are required for the implantation of this type of conversion. also, modifications in components and tuning for each engine have to be analyzed. This paper studies the effect of the conversion from gasoline to natural gas over the engine output, indicate mean pressure, combustion rate etc. It also analyze how to find the starting angle and the best air/fuel ratio for a specific engine, using a two-zone combustion model. (author)

  20. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetité, Bahia, Brazil

    Science.gov (United States)

    Pereira, Wagner de S.; Kelecom, Alphonse; Py Júnior, Delcy de Azevedo

    2008-08-01

    The uranium mining at Caetité (Uranium Concentrate Unit—URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5×103 μGy y-1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y-1, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  1. Natural Conversation Reconstruction Tasks: The Language Classroom as a Meeting Place

    Directory of Open Access Journals (Sweden)

    Jun Ohashi

    2009-08-01

    Full Text Available This paper, drawing on Pratt’s notion of ‘transculturation’ and Bhabha’s ‘third space’, presents an example of language learning tasks that empower learners’ agency and promote their cross-cultural awareness and sensitivities to a different set of cultural expectations, using a naturally occurred Japanese thanking episodes. The paper discusses the merits of Natural Conversation Reconstruction Tasks (NCRTs as a practical method for helping L2 learners develop this ‘intercultural competence’. It is based on a qualitative study of the results of one NCRT created for use in the context of teaching Japanese as a L2 in a multicultural society. It suggests the NCRT encourages the learners to explore the intersection where language use, speaker intention and L1 and L2 cultural norms meet. Such a process helps the learners become aware of socially expected patterns of communication in L1 and L2 in terms of the choices of speech act, formulaic expressions, sequential organization and politeness orientation. The learners’ comments suggest that the NCRT helps learners transcend their cultural boundaries by overcoming their narrow understanding of ‘thanking’ as ‘expressions of gratitude and appreciation’ and by cross-culturally widening their views of what counts as thanking. The NCRT with rich contextual information promotes the learners’ intercultural awareness, sensitivity to context and intercultural exploration in the space between L1 and L2, where they have authority and freedom of making sense of conversations, and pragmatics is fully integrated into language pedagogy.

  2. INTRAVAL phase 2, test case 8, Alligator Rivers Natural Analogue: Modelling of uranium transport in the weathered zone at Koongarra (Australia)

    Energy Technology Data Exchange (ETDEWEB)

    Van de Weerd, H.; Leijnse, A.; Hassanizadeh, S.M.; Richardson-van der Poel, M.A.

    1994-04-01

    The purpose of this study is to test the simulation package METROPOL, developed at RIVM to simulate transport of radionuclides over large time scales. At the Koongarra site secondary uranium mineralization and dispersed uranium is present from the surface down to the base of weathering. Field data are analyzed to choose a modelling approach, to estimate model inputs and to test model results. Field data show that three layers can be distinguished in the Koongarra area: (1) a top layer which is fully weathered, (2) an intermediate layer which is partially weathered (the transition zone) and (3) a lower layer which is unweathered. The groundwater velocities are largest in the transition zone which has been moving downward as the weathering process proceeds. The finite element code METROPOL has been adapted to account for the movement of the transition zone and to describe the dissolution of uranium in the orebody by a non-equilibrium relation. In simulations taking into account the downward movement of the transition zone, the dispersion patterns at all depths are simulated. These simulations result in a pseudo steady state situation. Despite the fact that the model results presented are not fully in agreement with the dispersion patterns, it is expected that the present situation may be obtained by changing some of the model parameters. In this study it was shown that over large timescales geologic processes may have an impact on the transport of radionuclides, and the movement of the transition zone will have an impact on the uranium concentration distribution. The simulation results are influenced by the parameters values, which are difficult to estimate for a period of some million years. The largest uncertainties are associated with the boundary conditions. Continuation of natural analogue studies in the framework of nuclear waste disposal research is highly recommended. 24 figs., 13 tabs., 2 appendices, 39 refs.

  3. Dating by fission track method: study of neutron dosimetry with natural uranium thin films; Datacao com o metodo dos tracos de fissao: estudo da dosimetria de neutrons com filmes finos de uranio natural

    Energy Technology Data Exchange (ETDEWEB)

    Iunes, P.J.

    1990-06-01

    Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of {sup 238} U and the use of neutron dosimetry in fission track analysis. Experimental procedures using thin films of natural uranium as neutron dosimeters and its results are presented. The author shows a intercomparison between different thin films and between the dosimetry with thin film and other dosimetries. (M.V.M.). 52 refs, 12 figs, 9 tabs.

  4. Fabrication of uranium-based ceramics using internal gelation for the conversion of trivalent actinides; Herstellung uranbasierter Keramiken mittel interner Gelierung zur Konversion trivalenter Actinoiden

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, Henrik

    2012-07-01

    Alternative to today's direct final waste disposal strategy of long-lived radionuclides, for example the minor actinides neptunium, americium, curium and californium, is their selective separation from the radioactive wastestream with subsequent transmutation by neutron irradiation. Hereby it is possible to obtain nuclides with a lower risk-potential concerning their radiotoxicity. 1 neutron irradiation can be carried out either with neutron sources or in the next generation of nuclear reactors. Before the treatment, the minor actinides need to be converted in a suitable chemical and physical form. Internal gelation offers a route through which amorphous gel-spheres can be obtained directly from a metal-salt solution. Due to the presence of different types of metal ions as well as changing pH-values in a stock solution, a complex hydrolysis behaviour of these elements before and during gelation occurs. Therefore, investigations with uranium and neodymium as a minor actinide surrogate were carried out. As a result of suitable gelation-parameters, uraniumneodymium gel-spheres were successfully synthesised. The spheres also stayed intact during the subsequent thermal treatment. Based upon these findings, uranium-plutonium and uranium-americium gels were successfully created. For theses systems, the determined parameters for the uraniumneodymium gelation could also be applied. Additionally, investigations to reduce the acidity of uranium-based stock solutions for internal gelation were carried out. The necessary amount of urea and hexamethylenetetramine to induce gelation could hereby be decreased. This lead to a general increase of the gel quality and made it possible to carry out uranium-americium gelation in the first place. To investigate the stability of urea and hexamethylenetetramine, solutions of these chemicals were irradiated with different radiation doses. These chemicals showed a high stability against radiolysis in aqueous solutions.

  5. Reactor Physics Methods and Preconceptual Core Design Analyses for Conversion of the Advanced Test Reactor to Low-Enriched Uranium Fuel Annual Report for Fiscal Year 2012

    Energy Technology Data Exchange (ETDEWEB)

    David W. Nigg; Sean R. Morrell

    2012-09-01

    Under the current long-term DOE policy and planning scenario, both the ATR and the ATRC will be reconfigured at an appropriate time within the next several years to operate with low-enriched uranium (LEU) fuel. This will be accomplished under the auspices of the Reduced Enrichment Research and Test Reactor (RERTR) Program, administered by the DOE National Nuclear Security Administration (NNSA). At a minimum, the internal design and composition of the fuel element plates and support structure will change, to accommodate the need for low enrichment in a manner that maintains total core excess reactivity at a suitable level for anticipated operational needs throughout each cycle while respecting all control and shutdown margin requirements and power distribution limits. The complete engineering design and optimization of LEU cores for the ATR and the ATRC will require significant multi-year efforts in the areas of fuel design, development and testing, as well as a complete re-analysis of the relevant reactor physics parameters for a core composed of LEU fuel, with possible control system modifications. Ultimately, revalidation of the computational physics parameters per applicable national and international standards against data from experimental measurements for prototypes of the new ATR and ATRC core designs will also be required for Safety Analysis Report (SAR) changes to support routine operations with LEU. This report is focused on reactor physics analyses conducted during Fiscal Year (FY) 2012 to support the initial development of several potential preconceptual fuel element designs that are suitable candidates for further study and refinement during FY-2013 and beyond. In a separate, but related, effort in the general area of computational support for ATR operations, the Idaho National Laboratory (INL) is conducting a focused multiyear effort to introduce modern high-fidelity computational reactor physics software and associated validation protocols to replace

  6. The Chemistry and Toxicology of Depleted Uranium

    Directory of Open Access Journals (Sweden)

    Sidney A. Katz

    2014-03-01

    Full Text Available Natural uranium is comprised of three radioactive isotopes: 238U, 235U, and 234U. Depleted uranium (DU is a byproduct of the processes for the enrichment of the naturally occurring 235U isotope. The world wide stock pile contains some 1½ million tons of depleted uranium. Some of it has been used to dilute weapons grade uranium (~90% 235U down to reactor grade uranium (~5% 235U, and some of it has been used for heavy tank armor and for the fabrication of armor-piercing bullets and missiles. Such weapons were used by the military in the Persian Gulf, the Balkans and elsewhere. The testing of depleted uranium weapons and their use in combat has resulted in environmental contamination and human exposure. Although the chemical and the toxicological behaviors of depleted uranium are essentially the same as those of natural uranium, the respective chemical forms and isotopic compositions in which they usually occur are different. The chemical and radiological toxicity of depleted uranium can injure biological systems. Normal functioning of the kidney, liver, lung, and heart can be adversely affected by depleted uranium intoxication. The focus of this review is on the chemical and toxicological properties of depleted and natural uranium and some of the possible consequences from long term, low dose exposure to depleted uranium in the environment.

  7. Capital and operating costs of irradiated natural uranium reprocessing plants; Couts d'investissement et d'exploitation des usines de retraitement de l'uranium naturel irradie

    Energy Technology Data Exchange (ETDEWEB)

    Thiriet, L.; Jouannaud, C.; Couture, J.; Duboz, J. [Commissariat a l' Energie Atomique (France). Centre d' Etudes Nucleaires; Oger, C. [Saint Gobain Nucleaire (France)

    1966-07-01

    This paper presents first a method of analysing natural uranium reprocessing plants investment costs (method similar to LANG and BACH well known in the fuel oil industry) and their operating costs (analysed according to their economic type). This method helps establishing standard cost structures for these plants, allowing thus comparisons between existing or planned industrial facilities. It also helps evaluating the foreseeable consequences of technical progress. Some results obtained are given, concerning: the investment costs sensitivity to the various technical parameters defining the fuel and their comparison according to the country or the economic area taken into account. Finally, the influence of the plants size on their investment costs is shown. (author) [French] La communication expose d'abord une methode d'analyse des couts d'investissement des usines de retraitement de l'uranium naturel irradie (inspiree de celles de LANG et de BACH, bien connues dans l'industrie petroliere) et de leurs couts d'exploitation (selon leur nature economique). Cette methode permet d'etablir des structures types de couts de ces usines et de comparer les realisations industrielles et les projets. Elle facilite l'exploration des consequences previsibles du progres technique. On indique un certain nombre de resultats obtenus, concernant la sensibilite des couts d'investissement de ces usines aux differents parametres techniques definissant le combustible et leur confrontation selon les pays ou aires economiques envisages. On montre enfin comment doit pouvoir s'exprimer l'influence de la taille des usines sur leur cout d'investissement. (auteur)

  8. Natural gas conversion to higher hydrocarbons using plasma interactions with surfaces. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sackinger, W.M.; Kamath, V.A.; Morgan, B.L.; Airey, R.W.

    1993-12-01

    Experiments are reported in which a methane plasma is created, and the methyl ions and hydrogen ions are accelerated within a microchannel array so that they interact with neutral methane molecules on the inside surfaces of the microchannels. No catalysts are used, and the device operates at room temperature. Impact energies of the ions are in the range of 10 eV to greater than 100 eV, and the energy delivered in the interaction at the surfaces causes the production of larger hydrocarbon molecules, such as C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}, along with C{sub 3}, C{sub 4}, C{sub 5}m C{sub 6}, C{sub 7}m and C{sub 8} molecules. There is a decreasing percentage of larger molecules produced, in comparison with the C{sub 2} and C{sub 3} types. Conversion effectiveness is greater at higher pressure, due to the increased ionic activity. The yield of the higher hydrocarbons depends upon the external voltage used, and voltage can be used as a control parameter to adjust the output mixture proportions. A conversion energy of 2.59 kilowatt hours/killogram of output has been demonstrated, and a reduction of this by a factor of 10 is possible using known techniques. In batch experiments, the selectivity for C{sub 2} has varied from 47% to 88%, and selectivity for C{sub 6} has ranged from 0% to 12.8%. Other hydrocarbon selectivities also span a wide and useful range. The estimated costs for hydrocarbons produced with this technology are in the range of $200 per tonne, in production quantities, depending upon natural gas costs. Pilot production experiments are recommended to make these estimates more precise, and to address strategies for scaling the technology up to production levels. Applications are discussed.

  9. Steady-state analysis of the integrated natural gas and electric power system with bi-directional energy conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Fang, Jiakun; Li, Jinghua

    2016-01-01

    Nowadays, the electric power system and natural gas network are becoming increasingly coupled and interdependent. A harmonized integration of natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables in terms of system...... flexibility. This work focuses on the steady-state analysis of the integrated natural gas and electric power system with bi-directional energy conversion. A unified energy flow formulation is developed to describe the nodal balance and branch flow in both systems and it is solved with the Newton......–Raphson method. Both the unification of units and the per-unit system are proposed to simplify the system description and to enhance the computation efficiency. The applicability of the proposed method is demonstrated by analyzing an IEEE-9 test system integrated with a 7-node natural gas network. Later, time...

  10. Evaluating the effectiveness of dilution of the recovered uranium with depleted uranium and low-enriched uranium to obtain fuel for VVER reactors

    Science.gov (United States)

    Smirnov, A. Yu; Sulaberidze, G. A.; Dudnikov, A. A.; Nevinitsa, V. A.

    2016-09-01

    The possibility of the recovered uranium enrichment in a cascade of gas centrifuges with three feed flows (depleted uranium, low-enriched uranium, recovered uranium) with simultaneous dilution of U-232,234,236 isotopes was shown. A series of numerical experiments were performed for different content of U-235 in low-enriched uranium. It has been demonstrated that the selected combination of diluents can simultaneously reduce the cost of separative work and the consumption of natural uranium, not only with respect to the previously used multi-flow cascade schemes, but also in comparison to the standard cascade for uranium enrichment.

  11. Compact conversion of natural gas and biomass to DME in microstructured reactors

    Energy Technology Data Exchange (ETDEWEB)

    Myrstad, Rune

    2010-07-01

    Efficient production of easily distributable fuel from natural gas or biomass in the small-to-medium scale calls for a more compact and efficient process than using conventional technology. Microstructured reactors have improved heat and mass transfer properties which make them suitable for process intensified production of liquid fuel from synthesis gas and demonstration plants using such technology are announced. Dimethyl ether (DME) can be used as an intermediate in the production of several industrial chemicals and DME is also used as an aerosol propellant because of its environmentally benign properties. Since DME has high cetane number and is considered as an ultra-clean fuel with reduced NO{sub x}, SO{sub x}, and PM emissions, DME has emerged as a substitute for auto diesel fuel and bio-DME is one of the most promising second-generation biofuels. DME can be prepared in a one-step process from synthesis gas, which is thermodynamically and economically favourable to the two step process consisting of methanol synthesis followed by dehydration of methanol to DME. As the direct process is strongly exothermic, the reaction heat has to be effectively removed from the reaction system in order to maintain a safe and economic operational mode. Direct DME synthesis possesses a high volumetric heat production rate and hence the temperature control is a main challenge. Besides this, parameters such as syngas composition, pressure, contact time and catalytic system affect the conversion and yield. In this work direct DME synthesis from syngas in a microstructured packed bed reactor was demonstrated to operate at practically isothermal conditions. The performance of the catalyst was enhanced by elimination of the undesired phenomena related to the exothermic process, such as hot spot formation and side reactions. The influence of process parameters on methanol selectivity and DME productivity was studied. The highest CO conversion was achieved by a H{sub 2}-rich syngas at

  12. Estimation of ionizing radiation impact on natural Vicia cracca populations inhabiting areas contaminated with uranium mill tailings and radium production wastes

    Energy Technology Data Exchange (ETDEWEB)

    Evseeva, T.; Majstrenko, T. [Institute of Biology, Komi Scientific Center, Ural Division RAS, Kommunisticheskaya 28, 167982 Syktyvkar (Russian Federation); Geras' kin, S. [Russian Institute of Agricultural Radiology and Agroecology RAAS, 249020 Obninsk, Kaluga region (Russian Federation); Brown, J.E., E-mail: Justin.brown@nrpa.no [Norwegian Radiation Protection Authority, Grini naeringspark 13, 1332 Osteras (Norway); Belykh, E. [Institute of Biology, Komi Scientific Center, Ural Division RAS, Kommunisticheskaya 28, 167982 Syktyvkar (Russian Federation)

    2009-10-01

    Industrial areas in proximity to the Vodny settlement in the Komi Republic, Russia, have been contaminated by uranium mill tailings and radium production wastes. These areas, exhibiting high activity concentrations of naturally occurring radionuclides in soils, constitute a field laboratory where the effects of combined chronic exposures to {alpha}-, {beta}- and {gamma}-emitting radionuclides on natural plant populations can be studied. The aim of the present work was to determine dose-effect relationships and the range of doses that cause biological effects in natural Vicia cracca L. populations inhabiting the study area. The studied plant species is native to the area and is found ubiquitously. Soil and vegetation samples were taken at a reference location and six contaminated sites characterized by distinct floodplain depositional units with different enhanced levels of naturally occurring radionuclides. A large fraction of the dose at the study sites (including the reference location) was attributable to internal irradiation and {sup 226}Ra was found to be an important contributor to this component of dose. The relationship between the frequency of chromosome aberrations in seedlings' root tip cells and the absorbed dose was found to be quadratic. An exponential model provided the best result in describing the empirical dependence between the absorbed dose and both the germination capacity of seeds and the survival rate of sprouts of V. cracca. For V. cracca plants inhabiting areas contaminated with uranium mill tailings and radium production wastes, a weighted absorbed dose of 0.2 Gy (weighting factor for alpha particles = 5) during the vegetation period could be considered to be a level below which no increase in genetic variability and decrease in reproductive capacity might be observed above background.

  13. Estimation of ionizing radiation impact on natural Vicia cracca populations inhabiting areas contaminated with uranium mill tailings and radium production wastes.

    Science.gov (United States)

    Evseeva, T; Majstrenko, T; Geras'kin, S; Brown, J E; Belykh, E

    2009-10-01

    Industrial areas in proximity to the Vodny settlement in the Komi Republic, Russia, have been contaminated by uranium mill tailings and radium production wastes. These areas, exhibiting high activity concentrations of naturally occurring radionuclides in soils, constitute a field laboratory where the effects of combined chronic exposures to alpha-, beta- and gamma-emitting radionuclides on natural plant populations can be studied. The aim of the present work was to determine dose-effect relationships and the range of doses that cause biological effects in natural Vicia cracca L. populations inhabiting the study area. The studied plant species is native to the area and is found ubiquitously. Soil and vegetation samples were taken at a reference location and six contaminated sites characterized by distinct floodplain depositional units with different enhanced levels of naturally occurring radionuclides. A large fraction of the dose at the study sites (including the reference location) was attributable to internal irradiation and (226)Ra was found to be an important contributor to this component of dose. The relationship between the frequency of chromosome aberrations in seedlings' root tip cells and the absorbed dose was found to be quadratic. An exponential model provided the best result in describing the empirical dependence between the absorbed dose and both the germination capacity of seeds and the survival rate of sprouts of V. cracca. For V. cracca plants inhabiting areas contaminated with uranium mill tailings and radium production wastes, a weighted absorbed dose of 0.2 Gy (weighting factor for alpha particles=5) during the vegetation period could be considered to be a level below which no increase in genetic variability and decrease in reproductive capacity might be observed above background.

  14. High surface-area amidoxime-based polymer fibers co-grafted with various acid monomers yielding increased adsorption capacity for the extraction of uranium from seawater.

    Science.gov (United States)

    Oyola, Yatsandra; Dai, Sheng

    2016-06-07

    Uranium is dissolved in the ocean at a uniform concentration of 3.34 ppb, which translates to approximately 4-5 billion tons of uranium. The development of adsorbents that can extract uranium from seawater has been a long term goal, but the extremely dilute uranium concentration along with the competition of other metal salts (which are at higher concentrations) has hindered the development of an economical adsorption process. Several acid monomers were co-grafted with acrylonitrile (AN) to help increase the hydrophilicity of the adsorbent to improve access to the metal adsorption sites. Grafting various acid monomers on PE fibers was found to significantly affect the uranium adsorption in simulated seawater in the following order: acrylic acid (AA) uranium adsorption capacity significantly increased when Mohr's salt was added with acrylic acid, most likely due to the reduction of co-polymerization of the monomers. When testing under more realistic conditions, the acid-grafted PE fiber adsorbents were exposed to natural seawater (more dilute uranium), the uranium adsorption capacity increased in the following order: MAA uranium adsorption capacity with each acid monomer was related to higher grafting of AN and therefore a higher conversion to amidoxime (AO).

  15. INTRAVAL phase 2, test case 8. Alligator Rivers Natural Analogue - Modelling of uranium transport in the weathered zone at Koongarra (Australia). Progress report

    NARCIS (Netherlands)

    van der Weerd H; Hassanizadeh SM; Richardson-van der Poel MA; LBG

    1993-01-01

    A study of uranium transport in the Koongarra site of Alligator Rivers Uranium deposit (Australia) is carried out. The analysis of the solid phase uranium concentration measured at various depths provides a useful picture of the dispersion process. Results of this analysis seem to support the

  16. INTRAVAL phase 2, test case 8. Alligator Rivers Natural Analogue - Modelling of uranium transport in the weathered zone at Koongarra (Australia). Progress report

    NARCIS (Netherlands)

    van der Weerd H; Hassanizadeh SM; Richardson-van der Poel MA; LBG

    1993-01-01

    A study of uranium transport in the Koongarra site of Alligator Rivers Uranium deposit (Australia) is carried out. The analysis of the solid phase uranium concentration measured at various depths provides a useful picture of the dispersion process. Results of this analysis seem to support the hypo

  17. Sensitive Determination of Uranium in Natural Waters Using UV-Vis Spectrometry After Preconcentration by Ion-Imprinted Polymer-Ternary Complexes.

    Science.gov (United States)

    Bicim, Tulin; Yaman, Mehmet

    2016-07-01

    The main purpose of this study was to achieve a substantial increase in the sensitivity of the uranium determination using UV-Vis spectrometry. To achieve this goal, ion-imprinted polymers were prepared for the uranyl (imprint) ion by the formation of a ternary (salicylaldoxime and 4-vinylpyridine) complex in 2-methoxy ethanol (porogen) following copolymerization with methacrylic acid. The synthesized polymers were characterized by FTIR analysis and thermogravimetric analysis. In the preconcentration step, the optimal pH was determined to be between values of 3.5 and 6.5. The adsorbed UO2(2+) was completely eluted by 10 mL of 3.0 mol L(-1) HClO4. The developed method was applied to uranium (VI) determination in natural water samples. By using the initial volume of 500 mL and final volume of 5 mL, a concentration of 1 μg L(-1) can be determined by applying the developed method in this study.

  18. Absorbed dose rate due to intake of natural radionuclides by Tilapia fish (Tilapia nilotica, Linnaeus, 1758) estimated near uranium anomaly at Santa Quiteria, Ceara, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de [Industrias Nucleares do Brasil S.A. (INB), Pocos de Caldas, MG (Brazil). Coordenacao de Protecao Radiologica. Unidade de Tratamento de Minerios], E-mail: wspereira@inb.gov.br; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Ciencia Ambiental; Py Junior, Delcy de Azevedo [Industrias Nucleares do Brasil S.A. (INB), Caetite, BA (Brazil). Coordenacao de Protecao Radiologica. Unidade de Concentrado de Uranio], E-mail: Delcy@inb.gov.br

    2007-07-01

    The uranium mining at Santa Quiteria (Santa Quiteria Unit - USQ) is in its environmental licensing phase. Aiming to estimate the radiological environmental impact of the USQ, a monitoring program is underway. However, radioprotection of biota is not explicitly mentioned in Brazilian norms. In order to preserve the biota of the deleterious effects from radiation and to behave in a pro-active way as expected by licensing organs, the present work aims to use an environmental protection methodology, based on the calculation of absorbed dose rate in biota. Thus, selected biomarker was the fish tilapia (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). Since there are no exposition limits for biota, in Brazil, the value proposed by the Department of Energy (DOE) of the United States of 3.5 x 10{sup 3} {mu}Gy/y has been used. The derived absorbed dose rate calculated for tilapia was 2.76 x 10{sup 0} {mu}Gy/y, that is less than 0.1 % of the limit established by DOE. The critical radionuclide was U-238, with 99% of the absorbed dose rate. This value of 0.1% of the limit allows to state that in pre-operational conditions analyzed natural radionuclides do not represent a radiological problem to the biota. (author)

  19. Epidemiological study of workers at risk of internal exposure to uranium; Etude epidemiologique des travailleurs exposes au risque d'incorporation d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Guseva Canu, I.

    2008-09-15

    This work is a pilot-study among nuclear fuel cycle workers potentially exposed to alpha radiation. Internal exposure from inhalation of uranium compounds during uranium conversion and enrichment operations was estimated at the AREVA NC Pierrelatte plant. A plant specific semi-quantitative job exposure matrix (JEM) was elaborated for 2709 workers employed at this plant between 1960 and 2006. The JEM has permitted to estimate the exposure to uranium and 16 other categories of pollutants and to calculate individual cumulative exposure score. Numerous correlations were detected between uranium compounds exposure and exposure to other pollutants, such as asbestos, ceramic refractive fibers, TCE and so on. 1968-2005 mortality follow-up showed an increasing risk of mortality from pleural cancer, rectal cancer and lymphoma on the basis of national mortality rates. Analyses of association between cancer mortality and uranium exposure suggested an increase in mortality due to lung cancer among workers exposed to slowly soluble uranium compounds derived from natural and reprocessed uranium. However these results are not statistically significant and based on a small number of observed deaths. These results are concordant with previously reported results from other cohorts of workers potentially exposed to uranium. Experimental studies of biokinetic and action mechanism of slowly soluble uranium oxides bear the biological plausibility of the observed results. Influence of bias was reduced by taking into account of possible confounding including co-exposure to other carcinogenic pollutants and tobacco consumption in the study. Nevertheless, at this stage statistical power of analyses is too limited to obtain more conclusive results. This pilot study shows the interest and feasibility of an epidemiological investigation among workers at risk of internal exposure to uranium and other alpha emitters at the national level. It demonstrates the importance of exposure assessment for

  20. INTRAVAL phase 2, test case 8. Alligator Rivers Natural Analogue. Modelling of uranium transport in the weathered zone at Koongarra, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Hassanizadeh, S.M.; Van de Weerd, H.; Richardson-Van der Poel, M.A. [National Inst. of Public Health and Environmental Protection RIVM, Bilthoven (Netherlands)

    1993-01-01

    Preliminary results of modelling of the dispersion of uranium in the weathered and transition zones are given. In the course of the Alligator Rivers Analogue Project (ARAP) more insight was gained about the formation of the dispersion fan and about the hydrology at Koongarra. The here applied transport modelling strategy takes into account those results. First, a general explanation of Natural Analogue is given, next to a brief description of the ARAP test case, carried out within the INTRAVAL phase 2. INTRAVAL is an international project concerned with the use of mathematical models for predicting the potential transport of radioactive solutes in the geosphere. Following is the analysis of chemical data, necessary for the choice of the modelling approach, for estimation of model inputs and for testing model results. Subsequently, the modelling strategy is expounded and a description is given of METROPOL, the transport code, used for modelling. 11 figs., 2 tabs., 1 appendix, 17 refs.

  1. Catalytic partial oxidation and membrane separation to optimize the conversion of natural gas to syngas and hydrogen.

    Science.gov (United States)

    Capoferri, Daniela; Cucchiella, Barbara; Iaquaniello, Gaetano; Mangiapane, Alessia; Abate, Salvatore; Centi, Gabriele

    2011-12-16

    The multistep integration of hydrogen-selective membranes into catalytic partial oxidation (CPO) technology to convert natural gas into syngas and hydrogen is reported. An open architecture for the membrane reactor is presented, in which coupling of the reaction and hydrogen separation is achieved independently and the required feed conversion is reached through a set of three CPO reactors working at 750, 750 and 920 °C, compared to 1030 °C for conventional CPO technology. Obtaining the same feed conversion at milder operating conditions translates into less natural gas consumption (and CO(2) emissions) and a reduction of variable operative costs of around 10 %. It is also discussed how this energy-efficient process architecture, which is suited particularly to small-to-medium applications, may improve the sustainability of other endothermic, reversible reactions to form hydrogen. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    -flow natural seawater at the Pacific Northwest National Laboratory (PNNL). Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis were used to characterize the adsorbent at different stages of adsorbent preparation and treatment. The study can be divided into two parts: (A) investigation of optimal parameters for KOH adsorbent conditioning and (B) investigation of other possible agents for alkali conditioning, including cost analysis on the basis of uranium production. In the first part of the study, tests with simulated seawater containing 8 ppm uranium showed that the uranium adsorption capacity increased with an increase in the KOH concentration and conditioning time and temperature at each of the KOH concentrations used. FTIR and solid state NMR studies indicated that KOH conditioning converts the amidoxime functional groups into more hydrophilic carboxylate. The longer the KOH conditioning time, up to three hours, the higher was the loading capacity from the simulated seawater solution which is composed of only uranyl, sodium, chloride, and carbonate ions. Marine testing with natural seawater, on the other hand, showed that the uranium adsorption capacity of the adsorbent increased with KOH conditioning temperature, and gradually decreased with increasing KOH conditioning time from one hour to three hours at 80 C. This behavior is due to the conversion of amidoxime to carboxylate. The carboxylate groups are needed to increase the hydrophilicity of the adsorbent; however, conversion of a significant amount of amidoxime to carboxylate leads to loss in selectivity toward uranyl ions. Thus, there is an optimum KOH conditioning time for each temperature at which an optimum ratio between amidoxime and carboxylate is reached. For the case of base conditioning with 0.44 M KOH at 80 C, the optimal conditioning time is 1 hour, with respect to the highest uranium loading capacity from

  3. Coherent Motion Reveals Non‐Ergodic Nature of Internal Conversion between Excited States

    DEFF Research Database (Denmark)

    Kuhlman, Thomas Scheby; Sølling, Theis I.; Møller, Klaus Braagaard

    2012-01-01

    for smaller molecules. Specifically, we focus on the S2→S1 internal conversion in cyclobutanone, cyclopentanone, and cyclohexanone. By means of time‐resolved mass spectrometry and photoelectron spectroscopy the relative rate of this transition is determined to be 13:2:1. Remarkably, we observe coherent...

  4. Magnesium carbide synthesis from methane and magnesium oxide - a potential methodology for natural gas conversion to premium fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, A.F.; Modestino, A.J.; Howard, J.B. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others

    1995-12-31

    Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

  5. 76 FR 58049 - Atomic Safety and Licensing Board; Honeywell International, Inc.; Metropolis Works Uranium...

    Science.gov (United States)

    2011-09-19

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Atomic Safety and Licensing Board; Honeywell International, Inc.; Metropolis Works Uranium... assurance for its Metropolis Works uranium conversion facility in Metropolis, Illinois. \\1\\ LBP-11-19,...

  6. Domestic utility attitudes toward foreign uranium supply

    Energy Technology Data Exchange (ETDEWEB)

    1981-06-01

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

  7. SSH gene expression profile of Eisenia andrei exposed in situ to a naturally contaminated soil from an abandoned uranium mine.

    Science.gov (United States)

    Lourenço, Joana; Pereira, Ruth; Gonçalves, Fernando; Mendo, Sónia

    2013-02-01

    The effects of the exposure of earthworms (Eisenia andrei) to contaminated soil from an abandoned uranium mine, were assessed through gene expression profile evaluation by Suppression Subtractive Hybridization (SSH). Organisms were exposed in situ for 56 days, in containers placed both in a contaminated and in a non-contaminated site (reference). Organisms were sampled after 14 and 56 days of exposure. Results showed that the main physiological functions affected by the exposure to metals and radionuclides were: metabolism, oxireductase activity, redox homeostasis and response to chemical stimulus and stress. The relative expression of NADH dehydrogenase subunit 1 and elongation factor 1 alpha was also affected, since the genes encoding these enzymes were significantly up and down-regulated, after 14 and 56 days of exposure, respectively. Also, an EST with homology for SET oncogene was found to be up-regulated. To the best of our knowledge, this is the first time that this gene was identified in earthworms and thus, further studies are required, to clarify its involvement in the toxicity of metals and radionuclides. Considering the results herein presented, gene expression profiling proved to be a very useful tool to detect earthworms underlying responses to metals and radionuclides exposure, pointing out for the detection and development of potential new biomarkers.

  8. The neurotoxicology of uranium.

    Science.gov (United States)

    Dinocourt, Céline; Legrand, Marie; Dublineau, Isabelle; Lestaevel, Philippe

    2015-11-01

    The brain is a target of environmental toxic pollutants that impair cerebral functions. Uranium is present in the environment as a result of natural deposits and release by human applications. The first part of this review describes the passage of uranium into the brain, and its effects on neurological functions and cognitive abilities. Very few human studies have looked at its cognitive effects. Experimental studies show that after exposure, uranium can reach the brain and lead to neurobehavioral impairments, including increased locomotor activity, perturbation of the sleep-wake cycle, decreased memory, and increased anxiety. The mechanisms underlying these neurobehavioral disturbances are not clearly understood. It is evident that there must be more than one toxic mechanism and that it might include different targets in the brain. In the second part, we therefore review the principal mechanisms that have been investigated in experimental models: imbalance of the anti/pro-oxidant system and neurochemical and neurophysiological pathways. Uranium effects are clearly specific according to brain area, dose, and time. Nonetheless, this review demonstrates the paucity of data about its effects on developmental processes and the need for more attention to the consequences of exposure during development.

  9. Mimicking nature: a novel peptide-based bio-inspired approach for solar energy conversion.

    Science.gov (United States)

    Gatto, Emanuela; Quatela, Alessia; Caruso, Mario; Tagliaferro, Roberto; De Zotti, Marta; Formaggio, Fernando; Toniolo, Claudio; Di Carlo, Aldo; Venanzi, Mariano

    2014-01-13

    A bioinspired approach is applied to photoelectric conversion devices. A 3(10)-helical hexapeptide bearing a pyrene unit is immobilized on a gold-covered TiO2 surface. The device is integrated for the first time in a dye-sensitized solar cell, exhibiting stability after several measurements. The approach could have promising applications in the field of optoelectronics. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Uranium industry annual 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    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.

  11. A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom

    Energy Technology Data Exchange (ETDEWEB)

    Milodowski, A.E.; Styles, M.T.; Hards, V.L. [Natural Environment Research Council (United Kingdom). British Geological Survey

    2000-08-01

    This report presents the results of a small-scale pilot study of the mineralogy and alteration characteristics of unusual sheet-like native copper occurring together with uraniferous and vanadiferous concretions in mudstones and siltstones of the Permian Littleham Mudstone Formation, at Littleham Cove, south Devon, England. The host mudstones and siltstones are smectitic and have been compacted through deep Mesozoic burial. The occurrence of native copper within these rocks represents a natural analogue for the long-term behaviour of copper canisters, sealed in a compacted clay (bentonite) backfill, that will be used for the deep geological disposal of high-level radioactive waste by the SKB. The study was undertaken by the British Geological Survey (BGS) on behalf of SKB between November 1999 and June 2000. The study was based primarily on archived reference material collected by the BGS during regional geological and mineralogical surveys of the area in the 1970's and 1980's. However, a brief visit was made to Littleham Cove in January 2000 to try to examine the native copper in situ and to collect additional material. Unfortunately, recent landslips and mudflows obscured much of the outcrop, and only one new sample of native copper could be collected. The native copper occurs as thin plates, up to 160 mm in diameter, which occur parallel to bedding in the Permian Littleham Mudstone Formation at Littleham Cove (near Budleigh Salterton) in south Devon. Each plate is made up of composite stacks of individual thin copper sheets each 1-2 mm thick. The copper is very pure (>99.4% Cu) but is accompanied by minor amounts of native silver (also pure - >99%) which occurs as small inclusions within the native copper. Detailed mineralogical and petrological studies of the native copper sheets, using optical petrography, backscattered scanning electron microscopy, X-ray diffraction analysis and electron probe microanalytical techniques, reveal a complex history of

  12. Study of the oocyte degenerescence at mouse: role of the caspases and toxicity of natural uranium; Etude de la degenerescence ovocytaire chez la souris: role des caspases et toxicite de l'uranium naturel

    Energy Technology Data Exchange (ETDEWEB)

    Arnault, E

    2008-04-15

    The aim of this work is to estimate the uranium toxicity on the ovarian function and on the oocyte and more fundamentally to characterize the molecular ways regulating the oocyte degenerescence. At first, will be described the different exposure modes at uranium and the known toxic effects of this heavy metal on man and animal. The mechanisms regulating the follicle genesis and the oogenesis are then developed. At last, will be given the data available in literature and concerning the apoptosis ways intervening in the follicular atresia and in the oocyte degenerescence while referring to the known ways of the somatic cells. (O.M.)

  13. Field-scale model for the natural attenuation of uranium at the Hanford 300 area using high performance computing

    Energy Technology Data Exchange (ETDEWEB)

    Lichtner, Peter C [Los Alamos National Laboratory; Hammond, Glenn E [PNNL

    2009-01-01

    Three-dimensional reactive flow and transport simulations are carried out to better understand the persistence of uranium [U(VI)] at the Hanford 300 Area bordering the Columbia River. The massively parallel code PFLOTRAN developed under a DOE SciDAC-2 project is employed in the simulations. The calculations were carried out on 4096 processor cores on ORNL's Jaguar XT4 & 5 Cray supercomputers with run times on the order of 6 hours, equivalent to several years if performed on a single processor with sufficient memory. A new conceptual model is presented for understanding present-day and future attenuation rates of U(VI) at the 300 Area site. Unique to the conceptual model is the recognition of three distinct phases in the evolution of the site corresponding to: (I) initial emplacement of waste; (II) present-day conditions of slow leaching of U(VI) from the Hanford sediments; and (III) the complete removal of non-labile U(VI) from the source region. This work focuses on Phase II. Both labile and non-labile forms of U(VI) are included in the model as sorbed and mineralized forms of U(VI), respectively. The non-labile form plays an important role in providing a long-term source of U(VI) as it slowly leaches out of the Hanford sediment. Rapid fluctuations in the Columbia River stage on hourly, weekly and seasonal time scales are found to' playa major role in determining the migration behavior of U(VI). The calculations demonstrate that U(VI) is released into the Columbia River at a highly fluctuating rate in a ratchet-like behavior with nonzero U(VI) flux occurring only during flow from contaminated sediment into the river. The cumulative flux, however, is found to increase approximately linearly with time. The flow rate and U(VI) flux into the Columbia River predicted by the model is highly sensitive to the value used in the conductance boundary condition at the river-sediment interface. By fitting the conductance to the measured piezometric head at well 399

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

    Energy Technology Data Exchange (ETDEWEB)

    Totemeier, T.C.

    1997-09-01

    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.

  15. Nature of Electronically Excited States of Organic Compounds and Processes of Nonradiative Conversion

    Science.gov (United States)

    Mayer, G. V.; Plotnikov, V. G.; Artyukhov, V. Ya.

    2016-08-01

    Models of quantum-chemical calculation of rate constants for internal processes and intersystem crossing in polyatomic molecules are considered. The influence of the nature of electronically excited states in organic compounds is investigated. It is shown that the explicit allowance for the nature of wave functions of electronic states for estimation of electronic matrix elements of nonadiabaticity operators and spin-orbit interaction allows photophysical processes in organic compounds to be considered in detail.

  16. Maximum permissible concentrations of uranium in air

    CERN Document Server

    Adams, N

    1973-01-01

    The retention of uranium by bone and kidney has been re-evaluated taking account of recently published data for a man who had been occupationally exposed to natural uranium aerosols and for adults who had ingested uranium at the normal dietary levels. For life-time occupational exposure to uranium aerosols the new retention functions yield a greater retention in bone and a smaller retention in kidney than the earlier ones, which were based on acute intakes of uranium by terminal patients. Hence bone replaces kidney as the critical organ. The (MPC) sub a for uranium 238 on radiological considerations using the current (1959) ICRP lung model for the new retention functions is slightly smaller than for earlier functions but the (MPC) sub a determined by chemical toxicity remains the most restrictive.

  17. Experimental Studies of the Effect of Permeability on Seismoelectric Conversion Coefficients in Natural and Synthetic Sandstones

    Science.gov (United States)

    Zhu, Z.; Toksoz, M. N.

    2014-12-01

    Theoretical calculation of seismoelectric conversion coefficients is difficult because it requires a large number of parameters that are hard to obtain. Much laboratory data are needed to validate the theoretical results. The most critical issue is determining independently the effect of porosity and permeability on seismoelectric coefficients. In general, when the rock porosity increases, the permeability increases too, and vice versa. In this study, we make measurements on both synthetic sandstone and two Berea (500 and 100) samples. We built a man-made "sandstone" sample with round cracks which are distributed in a horizontal plane. Thus the small cube (1.7 cm^3 ) only has one value of porosity and different permeabilities in the three directions. It is a sample with anisotropy in permeability. Laboratory experiments in a water tank show that the seismoelectric conversion coefficient is related to permeabilities in the three directions. The seismoelectric coefficient is highest in the direction of maximum permeability and lowest in the direction of minimum permeability. The measurements with the isotropic Berea samples show that seismoelectric coefficient increases with both porosity and permeability. Application of the result to borehole logging measurements requires analysis of the data from P, S, and Stoneley waves. P and Stoneley waves give large seismoelectric signals in the presence of fractures or high permeability zones. Shear waves, that do not induce fluid flow, provide very small seismoelectric signals. If the fracture strike in the formation is along the borehole axis, the P-wave induces stronger seismoelectric signal. Seismoelectric well logging might prove help for exploring the fractures or micro fractures in a borehole wall.

  18. Uranium industry in Canada

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    Current state of uranium industry in Canada has been considered. It is shown that in Canada, which is the major supplier of uranium, new methods of prospecting, mining and processing of uranium are developed and the old ones are improved. Owing to automation and mechanization a higher labour productivity in uranium ore mining is achieved. The uranium industry of Canada can satisfy the future demands in uranium but introduction of any new improvement will depend completely on the rate of nuclear power development.

  19. Realistic vs sudden turn-on of natural incoherent light: Coherences and dynamics in molecular excitation and internal conversion

    Energy Technology Data Exchange (ETDEWEB)

    Grinev, Timur; Brumer, Paul [Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)

    2015-12-28

    Molecular excitation with incoherent light is examined using realistic turn-on time scales, and results are compared to those obtained via commonly used sudden turn-on, or pulses. Two significant results are obtained. First, in contrast to prior studies involving sudden turn-on, realistic turn-on is shown to lead to stationary coherences for natural turn-on time scales. Second, the time to reach the final stationary mixed state, known to result from incoherent excitation, is shown to depend directly on the inverse of the molecular energy level spacings, in both sudden and realistic turn-on cases. The S{sub 0} → S{sub 2}/S{sub 1} internal conversion process in pyrazine is used as an example throughout. Implications for studies of natural light harvesting systems are noted.

  20. Realistic vs sudden turn-on of natural incoherent light: Coherences and dynamics in molecular excitation and internal conversion.

    Science.gov (United States)

    Grinev, Timur; Brumer, Paul

    2015-12-28

    Molecular excitation with incoherent light is examined using realistic turn-on time scales, and results are compared to those obtained via commonly used sudden turn-on, or pulses. Two significant results are obtained. First, in contrast to prior studies involving sudden turn-on, realistic turn-on is shown to lead to stationary coherences for natural turn-on time scales. Second, the time to reach the final stationary mixed state, known to result from incoherent excitation, is shown to depend directly on the inverse of the molecular energy level spacings, in both sudden and realistic turn-on cases. The S0 → S2/S1 internal conversion process in pyrazine is used as an example throughout. Implications for studies of natural light harvesting systems are noted.

  1. Airborne Plutonium and non-natural Uranium from the Fukushima DNPP found at 120 km distance a few days after reactor hydrogen explosions.

    Science.gov (United States)

    Shinonaga, Taeko; Steier, Peter; Lagos, Markus; Ohkura, Takehisa

    2014-04-01

    Plutonium (Pu) and non-natural uranium (U) originating from the Fukushima Daiichi Nuclear Power Plant (FDNPP) were identified in the atmosphere at 120 km distance from the FDNPP analyzing the ratio of number of atoms, following written as n(isotope)/n(isotope), of Pu and U. The n((240)Pu)/n((239)Pu), n((241)Pu)/n((239)Pu), n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U) in aerosol samples collected before and after the FDNPP incident were analyzed by accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICPMS). The activity concentrations of (137)Cs and (134)Cs in the same samples were also analyzed by gamma spectrometry before the destructive analysis. Comparing the time series of analytical data on Pu and U obtained in this study with previously reported data on Pu, U, and radioactive Cs, we concluded that Pu and non-natural U from the FDNPP were transported in the atmosphere directly over a 120 km distance by aerosol and wind within a few days after the reactor hydrogen explosions. Effective dose of Pu were calculated using the data of Pu: (130 ± 21) nBq/m(3), obtained in this study. We found that the airborne Pu contributes only negligibly to the total dose at the time of the incident. However the analytical results show that the amount of Pu and non-natural U certainly increased in the environment after the incident.

  2. The Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFC Focused on Hanford’s 300 Area Uranium Plume Quality Assurance Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fix, N. J.

    2008-01-31

    The purpose of the project is to conduct research at an Integrated Field-Scale Research Challenge Site in the Hanford Site 300 Area, CERCLA OU 300-FF-5 (Figure 1), to investigate multi-scale mass transfer processes associated with a subsurface uranium plume impacting both the vadose zone and groundwater. The project will investigate a series of science questions posed for research related to the effect of spatial heterogeneities, the importance of scale, coupled interactions between biogeochemical, hydrologic, and mass transfer processes, and measurements/approaches needed to characterize a mass-transfer dominated system. The research will be conducted by evaluating three (3) different hypotheses focused on multi-scale mass transfer processes in the vadose zone and groundwater, their influence on field-scale U(VI) biogeochemistry and transport, and their implications to natural systems and remediation. The project also includes goals to 1) provide relevant materials and field experimental opportunities for other ERSD researchers and 2) generate a lasting, accessible, and high-quality field experimental database that can be used by the scientific community for testing and validation of new conceptual and numerical models of subsurface reactive transport.

  3. Measurement of the High Energy Neutron Flux on the Surface of the Natural Uranium Target Assembly QUINTA Irradiated by Deuterons of 4 and 8 GeV Energy

    Science.gov (United States)

    Adam, J.; Baldin, A. A.; Chilap, V.; Furman, W.; Katovsky, K.; Khushvaktov, J.; Kumar, V.; Pronskikh, V.; Mar'in, I.; Solnyshkin, A.; Suchopar, M.; Tsupko-Sitnikov, V.; Tyutyunnikov, S.; Vrzalova, J.; Wagner, V.; Zavorka, L.

    Experiments with the natural uranium target assembly "QUINTA" exposed to 4 and 8 GeV deuteron beams of the Nuclotron accelerator at the Joint Institute for Nuclear Research (Dubna) are analyzed. The reaction rates of 27Al(n,y1)24Na, 27Al(n,y2)22Na and 27Al(n,y3)7Be reactions with effective threshold energies of 5, 27, and 119 MeV were measured at both 4 GeV and 8 GeV deuteron beam energies. The average neutron fluxes between the effective threshold energies and the effective ends of the neutron spectra (which are 800 or 1000 MeV for 4 or 8 GeV deuterons) were determined. The evidence for the intensity shift of the neutron spectra to higher neutron energies with the increase of the deuteron energy from 4 GeV to 8 GeV was found from the ratios of the average neutron fluxes. The reaction rates and the average neutron fluxes were calculated with the MCNPX 2.7 code.

  4. Experiences from the Swedish programme - heavy water and natural uranium in the Aagesta cogeneration plant; Erfarenheter av den svenska linjen tungt vatten och naturligt uran i Aagesta kraftvaermeverk

    Energy Technology Data Exchange (ETDEWEB)

    Oestman, Alvar

    2002-11-01

    A short review of the Swedish programme for nuclear power in the 50's and the 60's is given, and in particular a description of the operating experiences of the Aagesta nuclear cogeneration plant, producing district heating for the south Stockholm area (12 MW{sub el} and 68 MW{sub heat}). The original Swedish nuclear programme was built on heavy water and natural uranium and had the objective to construct small nuclear plants in the vicinity of some 10 large cities in south and middle Sweden. Aagesta was the only full-scale plant to be built according to this programme, as Sweden adopted the light-water reactor policy and eventually constructed 12 large reactors at four sites. The report is based on the experiences of the author from his work at the Aagesta plant in the sixties. In an appendix, the experiences from Vattenfall (the Swedish electric utility which took over the operating responsibility for the Aagesta plant), of the plant operation is reviewed.

  5. The Linguistic Correlates of Conversational Deception: Comparing Natural Language Processing Technologies

    Science.gov (United States)

    Duran, Nicholas D.; Hall, Charles; McCarthy, Philip M.; McNamara, Danielle S.

    2010-01-01

    The words people use and the way they use them can reveal a great deal about their mental states when they attempt to deceive. The challenge for researchers is how to reliably distinguish the linguistic features that characterize these hidden states. In this study, we use a natural language processing tool called Coh-Metrix to evaluate deceptive…

  6. Conversion of natural forest to managed forest plantations decreases tree resistance to prolonged droughts

    Science.gov (United States)

    Jean-Christophe Domec; John S. King; Eric Ward; A. Christopher Oishi; Sari Palmroth; Andrew Radecki; Dave M. Bell; Guofang Miao; Michael Gavazzi; Daniel M. Johnson; Steve G. McNulty; Ge Sun; Asko. Noormets

    2015-01-01

    Throughout the southern US, past forest management practices have replaced large areas of native forests with loblolly pine plantations and have resulted in changes in forest response to extreme weather conditions. However, uncertainty remains about the response of planted versus natural species to drought across the geographical range of these forests. Taking...

  7. Compressed Natural Gas Installation. A Video-Based Training Program for Vehicle Conversion. Instructor's Edition.

    Science.gov (United States)

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This instructor's guide contains the materials required to teach four competency-based course units of instruction in installing compressed natural gas (CNG) systems in motor vehicles. It is designed to accompany an instructional videotape (not included) on CNG installation. The following competencies are covered in the four instructional units:…

  8. Uranium Industry Annual, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-28

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

  9. Assessment of the potential for conversion of TP-108 boilers to firing natural gas and fuel oil

    Science.gov (United States)

    Tugov, A. N.; Supranov, V. M.; Izyumov, M. A.; Vereshchetin, V. A.; Usman, Yu. M.; Natal'in, A. S.

    2017-03-01

    TP-108 boilers were initially designed to burn milled peat. In the 1980s, they were reconstructed for conversion to burning natural gas as well. However, operation of these boilers revealed problems due to low reheat temperature and great air inleakage in the furnace. The initial design of the boiler and its subsequent reconstruction are described in the paper. Measures are presented for further modernization of TP-108 boilers to eliminate the above-mentioned problems and enable natural gas or fuel oil only to be burned in them. Thermal design calculations made using a specially developed adapted model (AM) suggest that replacement of the existing burners with new oil/gas burners, installation of steam-to-steam heat exchangers (SSHE), and sealing of the boiler gas path to make it gas tight will allow the parameters typical of gas-and-oil fired boilers to be attained. It is demonstrated that SSHEs can yield the design secondary steam reheat temperature, although this solution is not typical for natural circulation boilers with steam reheat. The boiler equipped with SSHEs can operate on fuel oil or natural gas with flue gas recirculation or without it. Moreover, operation of the boiler with flue gas recirculation to the air duct in combination with staged combustion enables the required environmental indicators to be attained.

  10. Gamma-ray characterization of uranium-series nuclides and its application to the study of the Pena Blanca natural analogue site, Chihuahua, Mexico

    Science.gov (United States)

    Wong, Virgina

    Two natural analogue sites located in the Pena Blanca Uranium District, Chihuahua, Mexico were characterized for radionuclide mobility. Analogue I is used to assess the long-term behavior of uranium-series nuclides in a host rock and geochemical environment that is similar to the proposed high-level waste repository at Yucca Mountain, Nevada. Analogue II represents a former dump site to assess short-term radionuclide mobility. Gamma-ray spectroscopy analysis was used to measure radioactivity of the U-series nuclides. Samples analyzed from Analogue I consist of: (1) fracture-infillings associated with different alteration assemblages collected within and outside the breccia pipe from various levels of the deposit and (2) fracture-infillings collected along an east-west trending fracture which intersects the breccia pipe and extends into the host rock. Alteration mineralogy, established via X-ray diffraction analysis, consists of pure kaolinite, a mixture of Fe-oxyhydroxide (goethite, hematite) With inclusions of jarosite and alunite, and carbonates. Results from activity ratios of 230Th/238U versus 226Ra/230Th indicate that majority of the Fe-oxyhydroxides from the breccia zone show a slight disequilibrium with respect to Ra enrichment and U depletion. This observation is modeled as requiring a multiple-event history of U mobility. An amorphous Fe sample distal to the breccia zone shows similar behavior but to a greater extent. This extreme behavior is ascribed to initially low U content and greater late-stage U removal. Two Fe-oxyhydroxide samples from Within the breccia pipe also display multiple-event stages but exhibit both Ra and U leaching. This behavior is shared by Fe-oxyhydroxide samples collected inside and peripheral to the breccia zone from the east-west trending fracture. Finally, three samples, two Fe phase samples outside the breccia zone and a kaolinite inside the breccia zone, show Ra and U enrichment. Also, a distal Fe-oxyhydroxide sample from the

  11. Contribution of Uranium-Bearing Evaporites to Plume Persistence Issues at a Former Uranium Mill Site Riverton, Wyoming, USA

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raymond [Navarro Research and Engineering; Dam, William [U.S. Department of Energy, Legacy Management; Campbell, Sam [Navarro Research and Engineering; Campbell, James [U.S. Geological Survey; Morris, Sarah [Navarro Research and Engineering; Tigar, Aaron [Navarrao Research and Engineering

    2016-08-01

    • Evaporites occur in an unsaturated silt layer, which is underlain by a sand and gravel aquifer. • These evaporites are rich in chloride across the site. • Uranium concentrations are higher in the evaporites that overlie the uranium contaminant plume. • Flooding can solubilize the evaporites in the silt layer and release chloride, sulfate (not shown), and uranium into the underlyingsand and gravel aquifer. • The uranium-rich evaporites can delay natural flushing, creating plume persistence near the Little Wind River.

  12. Steering the conversation: A linguistic exploration of natural language interactions with a digital assistant during simulated driving.

    Science.gov (United States)

    Large, David R; Clark, Leigh; Quandt, Annie; Burnett, Gary; Skrypchuk, Lee

    2017-09-01

    Given the proliferation of 'intelligent' and 'socially-aware' digital assistants embodying everyday mobile technology - and the undeniable logic that utilising voice-activated controls and interfaces in cars reduces the visual and manual distraction of interacting with in-vehicle devices - it appears inevitable that next generation vehicles will be embodied by digital assistants and utilise spoken language as a method of interaction. From a design perspective, defining the language and interaction style that a digital driving assistant should adopt is contingent on the role that they play within the social fabric and context in which they are situated. We therefore conducted a qualitative, Wizard-of-Oz study to explore how drivers might interact linguistically with a natural language digital driving assistant. Twenty-five participants drove for 10 min in a medium-fidelity driving simulator while interacting with a state-of-the-art, high-functioning, conversational digital driving assistant. All exchanges were transcribed and analysed using recognised linguistic techniques, such as discourse and conversation analysis, normally reserved for interpersonal investigation. Language usage patterns demonstrate that interactions with the digital assistant were fundamentally social in nature, with participants affording the assistant equal social status and high-level cognitive processing capability. For example, participants were polite, actively controlled turn-taking during the conversation, and used back-channelling, fillers and hesitation, as they might in human communication. Furthermore, participants expected the digital assistant to understand and process complex requests mitigated with hedging words and expressions, and peppered with vague language and deictic references requiring shared contextual information and mutual understanding. Findings are presented in six themes which emerged during the analysis - formulating responses; turn-taking; back

  13. Variation of uranium isotopic composition in soil within the JCO grounds from the 30 September 1999 criticality accident at JCO, Tokai-mura, Japan.

    Science.gov (United States)

    Yamamoto, Masayoshi; Kawabata, Yoshiko; Murata, Yoshimasa; Komura, Kazuhisa

    2002-08-01

    Following the 30 September 1999 criticality accident at JCO, 29 surface and 3 core soil samples were collected inside and outside the JCO grounds to evaluate possible contamination by 235U-enriched uranium (18.8%) being handled at the time of the accident. Uranium (234U, 235U, and 238U) and thorium (228Th, 230Th, and 232Th) isotopes were determined by alpha-spectrometry and ICP-MS after radiochemical separation. Concentrations of 238U and 234U ranged from 11.3 to 63.5 and 11.6 to 360 mBq g(-1), respectively. Higher amounts of 238U and/or 234U were found in the vicinity of the uranium conversion building. The calculated 234U/235U activity ratios ranged from a 1.0 radioactive equilibrium value to an unusually high 5.7 value. Several of the soil samples showed considerably higher 235U/238U atomic ratios (1.06-4.37%) than 0.725% for natural uranium. Based on the assumption that measured U-series nuclides in soil samples taken from the JCO grounds were almost at radioactive equilibrium up to 230Th, excess uranium could be calculated for each sample. The results suggest that the excess uranium in the soils have lower 235U/238U atomic ratios (a few %) than the 18.8% enrichment of the precipitation tank uranium.

  14. Agrowaste to vanillin conversion by a natural Pediococcus acidilactici strain BD16.

    Science.gov (United States)

    Chakraborty, Debkumar; Kaur, Baljinder; Obulisamy, Karthikeyan; Selvam, Ammaiyappan; Wong, Jonathan W C

    2016-10-13

    Owing to its flavoring, antimicrobial, antioxidant and anticarcinogenic nature, vanillin is widely used in foods, beverages, perfumes and pharmaceutical products. Ferulic acid (FA) is an important precursor of vanillin which is abundant in cereals like maize, rice and wheat and sugar beet. A major drawback of microbial vanillin production from FA is the degradation and biotransformation of toxic vanillin to other phenolic derivatives. The present study is undertaken to explore microbial vanillin production from FA precursor rice bran by employing vanillin-resistant Pediococcus acidilactici BD16, a natural lactic acid bacteria isolate. Extracellular, intracellular and cellular vanillin dehydrogenase activity was found least, which was minimized vanillin degradation, and the strain resists more than 5 g L(-1) vanillin in the medium. A metabolomics approach was followed for the detection of FA, vanillin and other metabolites generated during fermentation of rice bran medium. A metabolic pathway was also predicted for vanillin biosynthesis. Approximately 1.06 g L(-1) of crude vanillin was recovered from rice-bran-containing medium and this further offers scope for the industrial utilization of the organism and its genetic manipulation to enhance production of biovanillin.

  15. Combining natural language processing and network analysis to examine how advocacy organizations stimulate conversation on social media.

    Science.gov (United States)

    Bail, Christopher Andrew

    2016-10-18

    Social media sites are rapidly becoming one of the most important forums for public deliberation about advocacy issues. However, social scientists have not explained why some advocacy organizations produce social media messages that inspire far-ranging conversation among social media users, whereas the vast majority of them receive little or no attention. I argue that advocacy organizations are more likely to inspire comments from new social media audiences if they create "cultural bridges," or produce messages that combine conversational themes within an advocacy field that are seldom discussed together. I use natural language processing, network analysis, and a social media application to analyze how cultural bridges shaped public discourse about autism spectrum disorders on Facebook over the course of 1.5 years, controlling for various characteristics of advocacy organizations, their social media audiences, and the broader social context in which they interact. I show that organizations that create substantial cultural bridges provoke 2.52 times more comments about their messages from new social media users than those that do not, controlling for these factors. This study thus offers a theory of cultural messaging and public deliberation and computational techniques for text analysis and application-based survey research.

  16. Uranium processing and properties

    CERN Document Server

    2013-01-01

    Covers a broad spectrum of topics and applications that deal with uranium processing and the properties of uranium Offers extensive coverage of both new and established practices for dealing with uranium supplies in nuclear engineering Promotes the documentation of the state-of-the-art processing techniques utilized for uranium and other specialty metals

  17. Reactors for Catalytic Methanation in the Conversion of Biomass to Synthetic Natural Gas (SNG).

    Science.gov (United States)

    Schildhauer, Tilman J; Biollaz, Serge M A

    2015-01-01

    Production of Synthetic Natural Gas (SNG) from biomass is an important step to decouple the use of bioenergy from the biomass production with respect to both time and place. While anaerobic digestion of wet biomass is a state-of-the art process, wood gasification to producer gas followed by gas cleaning and methanation has only just entered the demonstration scale. Power-to-Gas applications using biogas from biomass fermentation or producer gas from wood gasification as carbon oxide source are under development. Due to the importance of the (catalytic) methanation step in the production of SNG from dry biomass or within Power-to-Gas applications, the specific challenges of this step and the developed reactor types are discussed in this review.

  18. Nature-Inspired Design of Artificial Solar-to-Fuel Conversion Systems based on Copper Phosphate Microflowers.

    Science.gov (United States)

    Wang, Jing; Zhu, Ting; Ho, Ghim Wei

    2016-07-07

    Phosphates play significant roles in plant photosynthesis by mediating electron transportation and furnishing energy for CO2 reduction. Motivated by this, we demonstrate herein an artificial solar-to-fuel conversion system, involving versatile copper phosphate microflowers as template and titanium dioxide nanoparticles as host photocatalyst. The elaborate flowerlike architectures, coupled with a unique proton-reduction cycle from interchangeability of different species of orthophosphate ions, not only offer a 2D nanosheet platform for an optimal heterostructure interface but also effectively augment charge-carrier transfer, thereby contributing to enhanced photoactivity and hydrogen generation. These nature-inspired, phosphate-derived nanocomposites advance the synthesis of a large variety of functional materials, which holds great potential for photochemical, photoelectric and catalytic applications.

  19. A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom

    Energy Technology Data Exchange (ETDEWEB)

    Milodowski, A.E.; Styles, M.T.; Hards, V.L. [Natural Environment Research Council (United Kingdom). British Geological Survey

    2000-08-01

    This report presents the results of a small-scale pilot study of the mineralogy and alteration characteristics of unusual sheet-like native copper occurring together with uraniferous and vanadiferous concretions in mudstones and siltstones of the Permian Littleham Mudstone Formation, at Littleham Cove, south Devon, England. The host mudstones and siltstones are smectitic and have been compacted through deep Mesozoic burial. The occurrence of native copper within these rocks represents a natural analogue for the long-term behaviour of copper canisters, sealed in a compacted clay (bentonite) backfill, that will be used for the deep geological disposal of high-level radioactive waste by the SKB. The study was undertaken by the British Geological Survey (BGS) on behalf of SKB between November 1999 and June 2000. The study was based primarily on archived reference material collected by the BGS during regional geological and mineralogical surveys of the area in the 1970's and 1980's. However, a brief visit was made to Littleham Cove in January 2000 to try to examine the native copper in situ and to collect additional material. Unfortunately, recent landslips and mudflows obscured much of the outcrop, and only one new sample of native copper could be collected. The native copper occurs as thin plates, up to 160 mm in diameter, which occur parallel to bedding in the Permian Littleham Mudstone Formation at Littleham Cove (near Budleigh Salterton) in south Devon. Each plate is made up of composite stacks of individual thin copper sheets each 1-2 mm thick. The copper is very pure (>99.4% Cu) but is accompanied by minor amounts of native silver (also pure - >99%) which occurs as small inclusions within the native copper. Detailed mineralogical and petrological studies of the native copper sheets, using optical petrography, backscattered scanning electron microscopy, X-ray diffraction analysis and electron probe microanalytical techniques, reveal a complex history of

  20. Conversion of electric bell type furnace for natural gas usage: a case study

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, Andre D.; Machado Junior, Antonio R.; Rocha, Ivan C.C. da; Azevedo, Jorge G.W. de; Konishi, Ricardo; Lehmkuhl, Willian A. [Companhia de Gas de Santa Catarina (SCGAS), Florianopolis, SC (Brazil); Nunes, Andrea T.; Possamai, Talita S.; Nicolau, Vicente de P. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-07-01

    In the present process of the heat treatment of normalizing of the crystalline structure of cast metal pieces, the heating is made by electric resistance arranged on the inner surfaces of the side walls of a bell furnace. Although electrical heating is suitable to obtain a uniform generation on the walls covered with electrical resistances, and is easy to control and operate with virtually no gas flow, it has some disadvantages such as poor movement of the heated ambient air, and higher cost. Heating occurs mostly by thermal radiation, with direct exchange between the resistors and the heated parts, but with a part serving as a barrier to the other, and with greater difficulty of heating the core loading. The details presented in this study, will simulate the process of heating by using electricity and using natural gas. In these simulations will be observed the distribution of temperature in the load and indoor over time and the rate of energy transferred to the load and also for the outside so to have a comparative processes. (author)

  1. Nondestructive analysis of the natural uranium mass through the measurement of delayed neutrons using the technique of pulsed neutron source; Analise nao destrutiva da massa de uranio natural atraves da medida de neutrons atrasados com o uso da tecnica de fonte pulsada de neutrons rapidos

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Paulo Rogerio Pinto

    1979-07-01

    This work presents results of non destructive mass analysis of natural uranium by the pulsed source technique. Fissioning is produced by irradiating the test sample with pulses of 14 MeV neutrons and the uranium mass is calculated on a relative scale from the measured emission of delayed neutrons. Individual measurements were normalised against the integral counts of a scintillation detector measuring the 14 MeV neutron intensity. Delayed neutrons were measured using a specially constructed slab detector operated in anti synchronism with the fast pulsed source. The 14 MeV neutrons were produced via the T(d,n) {sup 4}He reaction using a 400 kV Van de Graaff accelerated operated at 200 kV in the pulsed source mode. Three types of sample were analysed, namely: discs of metallic uranium, pellets of sintered uranium oxide and plates of uranium aluminium alloy sandwiched between aluminium. These plates simulated those of Material Testing Reactor fuel elements. Results of measurements were reproducible to within an overall error in the range 1.6 to 3.9%; the specific error depending on the shape, size and mass of the sample. (author)

  2. Uranium: myths and realities the depleted uranium; Uranio: Mitos y realidades. El caso del uranio emprobrecido

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, G.

    2001-07-01

    Uranium is an element whose name causes worry. The uranium properties are very unknown for people. However the element plays an important roll in the Earth as responsible of numerous natural phenomena, which are vital for life evolution. An example of the low knowledge about uranium has been the Balkan syndrome. A relation between cancers and the use of depleted uranium in ammunition in the Balkan War has been pretended to be established. From the beginning, this hypothesis could have been discarded as it has been confirmed and stated in recent reports of UNEP Commissions who have studied this matter. (Author)

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

    Science.gov (United States)

    Yeamans, Charles Burnett

    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 20°C 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 800°C 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 1150°C 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.

  4. Morphology Characterization of Uranium Particles From Laser Ablated Uranium Materials

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the study, metallic uranium and uranium dioxide material were ablated by laser beam in order to simulate the process of forming the uranium particles in pyrochemical process. The morphology characteristic of uranium particles and the surface of

  5. Anisotropic thermal conductivity in uranium dioxide.

    Science.gov (United States)

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

    2014-08-01

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

  6. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    -flow natural seawater at the Pacific Northwest National Laboratory (PNNL). Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis were used to characterize the adsorbent at different stages of adsorbent preparation and treatment. The study can be divided into two parts: (A) investigation of optimal parameters for KOH adsorbent conditioning and (B) investigation of other possible agents for alkali conditioning, including cost analysis on the basis of uranium production. In the first part of the study, tests with simulated seawater containing 8 ppm uranium showed that the uranium adsorption capacity increased with an increase in the KOH concentration and conditioning time and temperature at each of the KOH concentrations used. FTIR and solid state NMR studies indicated that KOH conditioning converts the amidoxime functional groups into more hydrophilic carboxylate. The longer the KOH conditioning time, up to three hours, the higher was the loading capacity from the simulated seawater solution which is composed of only uranyl, sodium, chloride, and carbonate ions. Marine testing with natural seawater, on the other hand, showed that the uranium adsorption capacity of the adsorbent increased with KOH conditioning temperature, and gradually decreased with increasing KOH conditioning time from one hour to three hours at 80 C. This behavior is due to the conversion of amidoxime to carboxylate. The carboxylate groups are needed to increase the hydrophilicity of the adsorbent; however, conversion of a significant amount of amidoxime to carboxylate leads to loss in selectivity toward uranyl ions. Thus, there is an optimum KOH conditioning time for each temperature at which an optimum ratio between amidoxime and carboxylate is reached. For the case of base conditioning with 0.44 M KOH at 80 C, the optimal conditioning time is 1 hour, with respect to the highest uranium loading capacity from

  7. Analysis of uranium isotope separation by redox chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Fujine, S.; Naruse, Y.; Shiba, K.

    1983-09-01

    Uranium isotope separation by redox chromatography is analytically studied. The periodic withdrawal of products and tails and the introduction of natural feed are simulated on the assumption of a square cascade for a uranium adsorption band. The influences on the separative power and the lead time until product withdrawal are investigated by varying the magnitude of the isotope separation factor, uranium band length, tails concentration, and so on. Simulating calculations indicate that using ion-exchange resins to achieve uranium isotope separation requires a very long lead time for the production of highly enriched uranium.

  8. Dry uranium tetrafluoride process preparation using the uranium hexafluoride reconversion process effluents

    Energy Technology Data Exchange (ETDEWEB)

    Silva Neto, J.B.; Urano de Carvalho, E.F.; Oliveira, F.B.V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: jbsneto@ipen.br; elitaucf@ipen.br; fabio@ipen.br; Riella, H.G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)]. E-mail: riella@enq.ufsc.br

    2007-07-01

    It is a well known fact that the use of uranium tetrafluoride allows flexibility in the production of uranium silicide and uranium oxide fuel. To its obtention there are two conventional routes, the one which reduces uranium from the UF{sub 6} hydrolysis solution with stannous chloride, and the hydrofluorination of a solid uranium dioxide. In this work we are introducing a third and a dry way route, mainly utilized to the recovery of uranium from the liquid effluents generated in the uranium hexafluoride reconversion process, at IPEN/CNEN-SP. Working in the liquid phase, this route comprises the recuperation of ammonium fluoride by NH{sub 4}HF{sub 2} precipitation. Working with the solid residues, the crystallized bifluoride is added to the solid UO{sub 2}, which comes from the U miniplates recovery, also to its conversion in a solid state reaction, to obtain UF{sub 4}. That returns to the process of metallic uranium production unity to the U{sub 3}Si{sub 2} obtention. This fuel is considered in IPEN-CNEN/SP as the high density fuel phase for IEA-R1m reactor, which will replace the former low density U{sub 3}O{sub 8}-Al fuel. (author)

  9. Uranium industry annual 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-05

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

  10. Uranium Provinces in China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Three uranium provinces are recognized in China, the Southeast China uranium province, the Northeast China-lnner Mongolia uranium province and the Northwest China (Xinjiang) uranium province. The latter two promise good potential for uranium resources and are major exploration target areas in recent years. There are two major types of uranium deposits: the Phanerozoic hydrothermal type (vein type) and the Meso-Cenozoic sandstone type in different proportions in the three uranium provinces. The most important reason or prerequisite for the formation of these uranium provinces is that Precambrian uranium-enriched old basement or its broken parts (median massifs) exists or once existed in these regions, and underwent strong tectonomagmatic activation during Phanerozoic time. Uranium was mobilized from the old basement and migrated upwards to the upper structural level together with the acidic magma originating from anatexis and the primary fluids, which were then mixed with meteoric water and resulted in the formation of Phanerozoic hydrothermal uranium deposits under extensional tectonic environments. Erosion of uraniferous rocks and pre-existing uranium deposits during the Meso-Cenozoic brought about the removal of uranium into young sedimentary basins. When those basins were uplifted and slightly deformed by later tectonic activity, roll-type uranium deposits were formed as a result of redox in permeable sandstone strata.

  11. Process for recovering uranium from waste hydrocarbon oils containing the same. [Uranium contaminated lubricating oils from gaseous diffusion compressors

    Science.gov (United States)

    Conrad, M.C.; Getz, P.A.; Hickman, J.E.; Payne, L.D.

    1982-06-29

    The invention is a process for the recovery of uranium from uranium-bearing hydrocarbon oils containing carboxylic acid as a degradation product. In one aspect, the invention comprises providing an emulsion of water and the oil, heating the same to a temperature effecting conversion of the emulsion to an organic phase and to an acidic aqueous phase containing uranium carboxylate, and recovering the uranium from the aqueous phase. The process is effective, simple and comparatively inexpensive. It avoids the use of toxic reagents and the formation of undesirable intermediates.

  12. Population-specific differences in gene conversion patterns between human SUZ12 and SUZ12P are indicative of the dynamic nature of interparalog gene conversion.

    Science.gov (United States)

    Mussotter, Tanja; Bengesser, Kathrin; Högel, Josef; Cooper, David N; Kehrer-Sawatzki, Hildegard

    2014-04-01

    Nonallelic homologous gene conversion (NAHGC) resulting from interparalog recombination without crossover represents an important influence on the evolution of duplicated sequences in the human genome. In 17q11.2, different paralogous sequences mediate large NF1 deletions by nonallelic homologous recombination with crossover (NAHR). Among these paralogs are SUZ12 and its pseudogene SUZ12P which harbour the breakpoints of type-2 (1.2-Mb) NF1 deletions. Such deletions are caused predominantly by mitotic NAHR since somatic mosaicism with normal cells is evident in most patients. Investigating whether SUZ12 and SUZ12P have also been involved in NAHGC, we observed gene conversion tracts between these paralogs in both Africans (AFR) and Europeans (EUR). Since germline type-2 NF1 deletions resulting from meiotic NAHR are very rare, the vast majority of the gene conversion tracts in SUZ12 and SUZ12P are likely to have resulted from mitotic recombination during premeiotic cell divisions of germ cells. A higher number of gene conversion tracts were noted within SUZ12 and SUZ12P in AFR as compared to EUR. Further, the distinctive signature of NAHGC (a high number of SNPs per paralog and a high number of shared SNPs between paralogs), a characteristic of many actively recombining paralogs, was observed in both SUZ12 and SUZ12P but only in AFR and not in EUR. A novel polymorphic 2.3-kb deletion in SUZ12P was identified which exhibited a high allele frequency in EUR. We postulate that this interparalog structural difference, together with low allelic recombination rates, could have caused a reduction in NAHGC between SUZ12 and SUZ12P during human evolution.

  13. URANIUM RECOVERY PROCESS

    Science.gov (United States)

    Bailes, R.H.; Long, R.S.; Olson, R.S.; Kerlinger, H.O.

    1959-02-10

    A method is described for recovering uranium values from uranium bearing phosphate solutions such as are encountered in the manufacture of phosphate fertilizers. The solution is first treated with a reducing agent to obtain all the uranium in the tetravalent state. Following this reduction, the solution is treated to co-precipitate the rcduced uranium as a fluoride, together with other insoluble fluorides, thereby accomplishing a substantially complete recovery of even trace amounts of uranium from the phosphate solution. This precipitate usually takes the form of a complex fluoride precipitate, and after appropriate pre-treatment, the uranium fluorides are leached from this precipitate and rccovered from the leach solution.

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

    Science.gov (United States)

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

    2014-12-01

    precipitation in the form of U6+ minerals. The δ238U 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.

  15. Uranium extraction by complexation with siderophores

    Science.gov (United States)

    Bahamonde Castro, Cristina

    One of the major concerns of energy production is the environmental impact associated with the extraction of natural resources. Nuclear energy fuel is obtained from uranium, an abundant and naturally occurring element in the environment, but the currently used techniques for uranium extraction leave either a significant fingerprint (open pit mines) or a chemical residue that alters the pH of the environment (acid or alkali leaching). It is therefore clear that a new and greener approach to uranium extraction is needed. Bioleaching is one potential alternative. In bioleaching, complexants naturally produced from fungi or bacteria may be used to extract the uranium. In the following research, the siderophore enterobactin, which is naturally produced by bacteria to extract and solubilize iron from the environment, is evaluated to determine its potential for complexing with uranium. To determine whether enterobactin could be used for uranium extraction, its acid dissociation and its binding strength with the metal of interest must be determined. Due to the complexity of working with radioactive materials, lanthanides were used as analogs for uranium. In addition, polyprotic acids were used as structural and chemical analogs for the siderophore during method development. To evaluate the acid dissociation of enterobactin and the subsequent binding constants with lanthanides, three different analytical techniques were studied including: potentiometric titration, UltraViolet Visible (UV-Vis) spectrophotometry and Isothermal Titration Calorimetry (ITC). After evaluation of three techniques, a combination of ITC and potentiometric titrations was deemed to be the most viable way for studying the siderophore of interest. The results obtained from these studies corroborate the ideal pH range for enterobactin complexation to the lanthanide of interest and pave the way for determining the strength of complexation relative to other naturally occurring metals. Ultimately, this

  16. Pragmatics: Teaching Natural Conversation

    Science.gov (United States)

    Houck, Noel R., Ed.; Tatsuki, Donna H., Ed.

    2011-01-01

    This volume offers teachers in the ESL/EFL classroom some of the first published materials for guiding learners past grammar into authentic-sounding (conventional) utterances and sequences, replacing the scripted unnatural or stilted dialogue provided in textbooks. Teachers will find a range of pedagogical activities to put to immediate use in the…

  17. Single-step scalable conversion of waste natural oils to carbon nanowhiskers and their interaction with mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Abheek [Indian Institute of Science Education and Research, Department of Chemical Sciences (India); Dutta, Priyanka [Indian Institute of Science Education and Research, Department of Biological Sciences (India); Sadhu, Anustup [Indian Institute of Science Education and Research, Department of Chemical Sciences (India); Maiti, Sankar [Indian Institute of Science Education and Research, Department of Biological Sciences (India); Bhattacharyya, Sayan, E-mail: sayanb@iiserkol.ac.in [Indian Institute of Science Education and Research, Department of Chemical Sciences (India)

    2013-07-15

    Waste cooking oil has daily deliberate hazardous effects on human health due to consumption of re-cooked oil and on the environment from disposal of the waste oil. These hazards can be controlled if there are ways to economically convert the waste oils into industrially relevant materials. Large-scale controlled catalytic conversion of the waste natural oils to carbon nanowhiskers (CNWs; diameter: 98-191 nm, length: {<=}2 {mu}m) was achieved by a one-pot, environmentally friendly process. The no-cost CNWs consist of carbon spirals with spacing between two adjacent layers at 3.1 {+-} 0.2 nm and arranged perpendicular to the whisker axis. The reactions were performed inside a sealed container at 500-850 Degree-Sign C and autogenic pressure for 4-10 h. It was demonstrated that the gaseous pressure from the decomposition of the fatty acids was crucial for formation of the semi-graphitic filamentous structures. The dilute acid-washed catalyst free CNWs were found to be negligibly toxic to the mammalian cells and can be localized inside the cell nucleus. The cellular internalization studies of the fluorescent CNWs demonstrated their viability as potential delivery vehicles into the mammalian cells.

  18. Determination of uranium transfer factors from soils contaminated with natural uranium along the Vereinigten Mulde in Zwickau; Bestimmung von Transferfaktoren von Uran aus natuerlich belasteten Boeden entlang der Zwickauer und Vereinigten Mulde

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Andreas

    2011-07-01

    According to IAEA the food chain soil-plants-human is the predominant radionuclide ingestion path. The consumption of contaminated vegetarian food causes a continuous radiation exposure. In this context the problem of contaminated meadows in the Zwickauer and Vereinigten Mulde that is used for agriculture is of predominant interest. In this area intensive uranium mining has caused severe environmental contamination. The agricultural crop land and the grass land were studied with respect to the radionuclides U-238 and U-234. Following the radiochemical separation using ion chromatography the samples were analyzed by alpha-spectrometry. Compared to non-contaminated areas significant specific activities were measured. The transfer factors of the radionuclides U-238 and U-234 were determined for different plant parts. The transfer factors decrease with increasing radioactive contamination of the soils.

  19. Cathodoluminescence of uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-08-09

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

  20. Uranium Processing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — An integral part of Y‑12's transformation efforts and a key component of the National Nuclear Security Administration's Uranium Center of Excellence, the Uranium...

  1. Enhancing Uranium Uptake by Amidoxime Adsorbent in Seawater: An investigation for optimum alkaline conditioning parameters

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.; Tsouris, Constantinos; Zhang, C.; Kim, J.; Brown, S.; Oyola, Yatsandra; Janke, C.; Mayes, R. T.; Kuo, Li-Jung; Wood, Jordana R.; Gill, Gary A.; Dai, Sheng

    2016-04-20

    A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory (ORNL) by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 ºC). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration of ~ 7-8 ppm and pH 8. FTIR and solid state NMR indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 ºC resulted in increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. Scanning electron microscopy showed that long conditioning times may also lead to adsorbent degradation

  2. Release of uranium from candidate wasteforms

    OpenAIRE

    Collier, N.; Harrison, M.; Brogden, M,; Hanson, B

    2012-01-01

    Large volumes of depleted natural and low-enriched uranium exist in the UK waste inventory. This work reports on initial investigations of the leaching performance of candidate glass and cement encapsulation matrices containing UO3 powder as well as that of uranium oxide powders. The surface areas of UO3 powder and the monolith samples of UO3 conditioned in the glass and cement matrices were very different making leaching comparisons difficult. The results showed that for both types of monoli...

  3. Selective Removal of Uranium from the Washing Solution of Uranium-Contaminated Soil

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Soo; Han, G. S.; Kim, G. N.; Koo, D. S.; Jeong, J. W.; Choi, J. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    This study examined selective removal methods of uranium from the waste solution by ion exchange resins or solvent extraction methods to reduce amount of the 2{sup nd} waste. Alamine-336, known as an excellent extraction reagent of uranium from the leaching solution of uranium ore, did not remove uranium from the acidic washing solution of soil. Uranyl ions in the acidic waste solution were sorbed on ampholyte resin with a high sorption efficiency, and desorbed from the resin by a washing with 0.5 M Na{sub 2}CO{sub 3} solution at 60 .deg. C. However, the uranium dissolved in the sulfuric acid solution was not sorbed onto the strong anion exchanger resins. A great amount of uranium-contaminated (U-contaminated) soil had been generated from the decommissioning of a uranium conversion plant. Our group has developed a decontamination process with washing and electrokinetic methods to decrease the amount of waste to be disposed of. However, this process generates a large amount of waste solution containing various metal ions.

  4. Treatment of effluents from uranium oxide production.

    Science.gov (United States)

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

    2011-01-01

    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.

  5. Uranium and free trade

    Energy Technology Data Exchange (ETDEWEB)

    1988-08-01

    This report was prepared by a working group of the Committee on International Trade in Uranium of the Uranium Institute. The report describes the general benefits of free trade and their relevance in the uranium market, and compares government restrictions on Western world uranium trade with those in other commodity markets. It is not directly concerned with restrictions designed to discourage nuclear weapons proliferation. The Uranium Institute and its members fully support the objective of nuclear non-proliferation. The report takes as given the current non-proliferation regime and focuses on economic and commercial restrictions imposed by governments on international trade in uranium, recognising that governments will always have a special interest in uranium trade owing to its potential weapons use. (author).

  6. India's Worsening Uranium Shortage

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Michael M.

    2007-01-15

    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 Commission’s Mid-Term Appraisal of the country’s 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 India’s 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.

  7. Geochemistry of natural radionuclide in soils surrounding a mining and plant uranium concentration;Geoquimica de radionuclindeos naturais em solos de areas circunvizinhas a uma unidade de mineracao e atividade de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Gildevan Viana, E-mail: gildevan.cardoso@vta.incra.gov.b [Instituto Nacional de Colonizacao e Reforma Agraria (INCRA), Rio de Janeiro, RJ (Brazil); Amaral Sobrinho, Nelson Moura Brasil do; Mazur, Nelson, E-mail: nelmoura@ufrrj.b, E-mail: nelmazur@ufrrj.b [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Inst. de Agronomia. Dept. de Solos; Wasserman, Maria Angelica Vergara, E-mail: angelica@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-11-15

    The environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. This study aimed to determine the geochemical partitioning of the natural radionuclides {sup 238}U, {sup 226}Ra and {sup 210}Pb in areas surrounding the Uranium Mining and Concentration Plant (URA) of the Brazilian Nuclear Industries S.A., in the uranium deposit region of Lagoa Real, in Caetite, southwestern Bahia state. Representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the URA. The level of total activity and geochemical fractionation (F1 slightly acidic, F2 reducible, F3 oxidisable, F4 alkaline, and F5 residual) were determined for the five areas. The average total radioactivity levels were, in Bq kg{sup -1} soil: 50 for {sup 238}U, 51 for {sup 226}Ra, and 159 for {sup 210}Pb. During the potentially bioavailable phase (F1) 11 % were extracted for {sup 238}U, 13 % for {sup 226}Ra and 3 % for {sup 210}Pb. The bioavailability of {sup 238}U was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of {sup 226}Ra, with the greatest bioavailability. {sup 210}Pb was predominantly associated with F5. The high percentage of {sup 238}U, {sup 226}Ra and {sup 210}Pb in the geochemical fraction F5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the URA activity. (author)

  8. Reactivity insertion transient analysis for KUR low-enriched uranium silicide fuel core

    OpenAIRE

    Shen, Xiuzhong; Nakajima, Ken; Unesaki, Hironobu; Mishima, Kaichiro

    2013-01-01

    The purpose of this study is to realize the full core conversion from the use of High Enriched Uranium (HEU) fuels to the use of Low Enriched Uranium (LEU) fuels in Kyoto University Research Reactor (KUR). Although the conversion of nuclear energy sources is required to keep the safety margins and reactor reliability based on KUR HEU core, the uranium density (3.2 gU/cm3) and enrichment (20%) of LEU fuel (U3Si2–AL) are quite different from the uranium density (0.58 gU/cm3) and enrichment (93%...

  9. Biosorption of uranium by human black hair.

    Science.gov (United States)

    Saini, Amardeep Singh; Melo, Jose Savio

    2015-04-01

    Naturally available low cost materials have gained importance as effective alternative to conventional sorbents for the removal of metal ions from water. The present study describes the use of black hair waste as a sorbent for the removal of uranium ions from an aqueous medium. Alkali treatment of the biomass resulted in a significant increase in its uptake capacity. The optimum pH and contact time for uranium removal were 4.5 and 2 h respectively. It was observed that the experimental data fits well in Ho's pseudo-second order kinetic model. Binding of uranium to the biomass was confirmed using FT-IR spectroscopy. Thus, the present study could demonstrate the utility of human black hair to remove uranium from aqueous medium.

  10. Uranium hexafluoride public risk

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-08-01

    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.

  11. Bioremediation of uranium contamination with enzymatic uranium reduction

    Science.gov (United States)

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

    1992-01-01

    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.

  12. Geology of the Sievi, Kuru and Askola sites. Uranium mineralogy at Askola

    Energy Technology Data Exchange (ETDEWEB)

    Markovaara-Koivisto, M.; Read, D.; Lindberg, A.; Siitari-Kauppi, M.; Togneri, L.

    2009-07-01

    The natural geochemical retardation systems of radioactive elements in the Finnish bedrock are of great relevance to the Finnish nuclear waste disposal programme. It indicates the likely fate of radionuclides released from the deep repository when the chemical environment is oxidizing within its operating stage or in the event of glacial melt water percolates to the repository. In these conditions the uranium occurs in its +6 state, and it is reactive and mobile. Studying uranium migration and retention in oxidizing conditions is thus justified. Uranium migration and retention are studied with samples taken from a natural uranium deposit at Askola. Likewise the uranium migration is studied with laboratory tests. The naturally uranium-rich samples are taken from shallow depths at Askola, and thus the behaviour of uranium can be studied in oxidising conditions. In the laboratory tests uranium is released from a depleted uranium disc and allowed to migrate and retain in Kuru grey granite and Sievi altered tonalite. The uranium is expected to migrate into the rock and to precipitate there as secondary phases. The rate of uranium migration and age of the precipitates in the laboratory experiments are known, but not in the case of the natural analogue studies. The observations from both the natural analogue and the laboratory tests will be used as input data for the coupled geochemical model for uranium migration and retention. (orig.)

  13. 一种用于铀同位素比值α能谱分析的磷化膜制源新技术%A New Source-preparation Technique of Phosphate Conversion Coating Used in the Determination of Uranium Isotope Ratio by Alpha Spectrometry

    Institute of Scientific and Technical Information of China (English)

    王哲; 王玉学; 郭冬发; 付琳; 黄秋红; 孙伟; 陈春军

    2016-01-01

    A new source-preparation technique of uranium phosphate conversion coating was developed for the determination of uranium isotope ratio by alpha spectrometry. It was found experimentally that under the conditions of 3.14 cm2 Ni-foil,0.5 mol/L HCl,2.5 mol/L NaCl ,0.08 mol/L KH 2 PO 4 ,20 g/L ascorbic acid ,25 mL initial solution,90℃ constant experiment temperature,1 60 r/min vibration frequency ,20 mm vibration amplitude,and 70min deposition time ,uranium less than 200 μg can be quantitatively and spontaneously converted into phosphorization film on Ni-foil. Compared to the tradi-tional source-preparation technique of electro-deposition,the technique of uranium phosphate conversion coating has the advantage of simple in electro-deposition device, easy in operation, high working-efficiency ,no interference in measuring lots of coexisting radionuclides such as 2 3 2 Th ,2 30 Th,22 6 Ra,2 3 1 Pa and so on in phosphating solution. The total spike recovery rate of uranium reaches 100% nearly,and the spectrum resolution is good in determing uranium isotope ratio by alpha spectrometry.%研发了一种用于铀同位素比值α能谱分析的磷化膜制源新技术.试验发现,当镍镀片面积为3.14 cm2,盐酸浓度为0.5 mol/L ,氯化钠浓度为2.5 mol/L ,磷酸二氢钾浓度为0.08 mol/L,抗坏血酸浓度为20 g/L,溶液体积为25 mL,恒温90℃,振荡速率为160次/min,振程20 mm 时,磷化膜制源70 min,200μg 以下的铀可在镍箔上定量转化为磷化膜.与传统的电沉积制源技术相比较,应用磷化膜制源技术进行测量源制备时无需电沉积装置,制源过程简单快速,工效高,大量共存的232 Th 、230 Th、226 Ra、231 Pa 等核素均不产生干扰,铀的全程回收率接近100%,α能谱峰分辨率较好.

  14. Chemical thermodynamics of uranium

    Energy Technology Data Exchange (ETDEWEB)

    Grenthe, I.; Fuger, J.; Lemire, R.J.; Muller, A.B.; Nguyen-Trung Cregu, C.; Wanner, H.

    1992-01-01

    A comprehensive overview on the chemical thermodynamics of those elements that are of particular importance in the safety assessment of radioactive waste disposal systems is provided. This is the first volume in a series of critical reviews to be published on this subject. The book provides an extensive compilation of chemical thermodynamic data for uranium. A description of procedures for activity corrections and uncertainty estimates is given. A critical discussion of data needed for nuclear waste management assessments, including areas where significant gaps of knowledge exist is presented. A detailed inventory of chemical thermodynamic data for inorganic compounds and complexes of uranium is listed. Data and their uncertainty limits are recommended for 74 aqueous complexes and 199 solid and 31 gaseous compounds containing uranium, and on 52 aqueous and 17 solid auxiliary species containing no uranium. The data are internally consistent and compatible with the CODATA Key Values. The book contains a detailed discussion of procedures used for activity factor corrections in aqueous solution, as well as including methods for making uncertainty estimates. The recommended data have been prepared for use in environmental geochemistry. Containing contributions written by experts the chapters cover various subject areas such a s: oxide and hydroxide compounds and complexes, the uranium nitrides, the solid uranium nitrates and the arsenic-containing uranium compounds, uranates, procedures for consistent estimation of entropies, gaseous and solid uranium halides, gaseous uranium oxides, solid phosphorous-containing uranium compounds, alkali metal uranates, uncertainties, standards and conventions, aqueous complexes, uranium minerals dealing with solubility products and ionic strength corrections. The book is intended for nuclear research establishments and consulting firms dealing with uranium mining and nuclear waste disposal, as well as academic and research institutes.

  15. PRODUCTION OF URANIUM

    Science.gov (United States)

    Ruehle, A.E.; Stevenson, J.W.

    1957-11-12

    An improved process is described for the magnesium reduction of UF/sub 4/ to produce uranium metal. In the past, there have been undesirable premature reactions between the Mg and the bomb liner or the UF/sub 4/ before the actual ignition of the bomb reaction. Since these premature reactions impair the yield of uranium metal, they have been inhibited by forming a protective film upon the particles of Mg by reacting it with hydrated uranium tetrafluoride, sodium bifluoride, uranyl fluoride, or uranium trioxide. This may be accomplished by adding about 0.5 to 2% of the additive to the bomb charge.

  16. METHOD OF ROLLING URANIUM

    Science.gov (United States)

    Smith, C.S.

    1959-08-01

    A method is described for rolling uranium metal at relatively low temperatures and under non-oxidizing conditions. The method involves the steps of heating the uranium to 200 deg C in an oil bath, withdrawing the uranium and permitting the oil to drain so that only a thin protective coating remains and rolling the oil coated uranium at a temperature of 200 deg C to give about a 15% reduction in thickness at each pass. The operation may be repeated to accomplish about a 90% reduction without edge cracking, checking or any appreciable increase in brittleness.

  17. Distributed secondary gas injection via a fractal injector: a nature-inspired approach to improving conversion in fluidized bed reactors

    NARCIS (Netherlands)

    Christensen, D.O.

    2008-01-01

    The conversion in bubbling fluidized bed reactors is suppressed because the interphase mass transfer and gas-solid contact in bubbling fluidized bed reactors are often poor. Most of the gas is present in the form of bubbles, which have low surface-to-volume ratios and are nearly devoid of catalyst

  18. Natural gas conversion program of Rio de Janeiro-Brazil; Projeto de conversao do sistema de distribuicao de gas canalizado na cidade do Rio de Janeiro

    Energy Technology Data Exchange (ETDEWEB)

    Pallottino, J.T.; Costa Filho, M.A.F.; Guarana, L.F.M.L. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil); Margalef, J.M. [Companhia Estadual de Gas (CEG), Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This paper presents the Conversion Project of Rio de Janeiro, Brazil, that converted all customers and the distribution network from Manufactured Gas (MG) to Natural Gas (NG), evaluating its logistic and benefits, highlighting those related to consumer safety. The Conversion Project was executed under the responsibility of CEG with the support of UERJ, specially on the definition and revision of the technical procedures as well as the quality assurance of the project execution. As main advantages followed by MG to NG network conversion, we can note: increasing of gas distribution network capacity and gas network operational condition improvements; elimination of production plant; revision and renovation of gas network; revision and repairing of building gas facilities; augmenting of NG usage; elimination of carbon monoxide as a supplied gas constituent. Conservation condition of most consumer internal gas facilities and ambient ventilation were so critical that conversion program resulted in no measurable accident prevention. The achieved safety level should be maintained through a periodically re-evaluation program of customer's gas facilities and appliances, with special focus on permanent ventilation required for NG safety usage. (author)

  19. Uranium industry annual 1993

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

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

  20. Assessment of Preferred Depleted Uranium Disposal Forms

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-06-01

    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.

  1. Preliminary Study on Chemical Components and Uranium Content of Calcium Fluoride Waste

    Institute of Scientific and Technical Information of China (English)

    LIANG; Xiao-hu; YANG; Lei; YANG; Jin-ling; SONG; Zhi-jun

    2013-01-01

    In the uranium conversion process,UF4 reduction is needed using calcium as reduction regent,so a great deal of calcium fluoride are generated,in which a no negligible amount of uranium(about 5%alleged)can be left in the calcium fluoride wastes by the entrainment effect.It is meaningful to extract and purify the uranium from these wastes,but chemical components of these waste is needed primarily.

  2. Uranium: abundance or shortage?

    Energy Technology Data Exchange (ETDEWEB)

    Steyn, J. [Energy Resources International, Inc., Washington, DC (United States)

    1997-09-01

    With large uranium stockpiles, particularly in the form of HEU, continuing to be the dominant factor in the world uranium market, buyers should be able to enter into attractive long-term commitments for the future. Nevertheless, producers are now able to see forward with some degree of certainty and are expected to meet their planned levels of production and demand. (author).

  3. Reports on investigations of uranium anomalies. National Uranium Resource Evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-10-01

    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.

  4. Effect of combining the metals of group VI supported on H-ZSM-5 zeolite as catalysts for non-oxidative conversion of natural gas to petrochemicals

    Institute of Scientific and Technical Information of China (English)

    A.K.Aboul-Gheit; A.E.Awadallah

    2009-01-01

    The most prestigious catalyst applied in natural gas (methane) non-oxidative conversion to petrochemicals is 6%Mo/H-ZSM-5.Chromium,molybdenum and tungsten are the group VI metals.Hence,in this work,6%Mo/H-ZSM-5 was correlated with 3%Cr+3%Mo/H-ZSM-5 and 3%W+3%Mo/H-ZSM-5 as catalysts to examine their promoting or inhibiting effects on the various reactions taking place during methane conversion.The catalytic activities of these catalysts were tested in a continuous flow fixed bed reactor at 700℃ and a GHSV of 1500 ml·g-1 ·h-1. Characterization of the catalysts using XRD,TGA and TPD were investigated.XRD and NH3-TPD showed greater interaction between the W-phase and the Bronsted acid sites in the channels of the zeolite than between Cr-phase and the acid sites in the zeolite.

  5. Uranium triamidoamine chemistry.

    Science.gov (United States)

    Gardner, Benedict M; Liddle, Stephen T

    2015-07-01

    Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren-uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium-metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren-uranium complexes.

  6. Uranium dioxide electrolysis

    Science.gov (United States)

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

    2009-12-29

    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.

  7. Uranium in groundwater--Fertilizers versus geogenic sources.

    Science.gov (United States)

    Liesch, Tanja; Hinrichsen, Sören; Goldscheider, Nico

    2015-12-01

    Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N=1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10 μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater.

  8. Evaluation of Uranium Concentration in Soil Samples of Central Jordan

    Directory of Open Access Journals (Sweden)

    Ned Xoubi

    2015-03-01

    Full Text Available Naturally occurring radionuclides such as uranium, thorium and their decay products (226Ra, 222Rn are present in a number of geological settings in Jordan. Motivated by the existence of uranium anomalies ‎coupled with its lack of conventional ‎‎energy ‎‎resources, Jordan decided that the development of ‎this indigenes ‎resource (uranium is the first step in introducing nuclear power as part of its energy mix. Uranium deposits in Central Jordan were perceived not only as a secured resource that will ‎fulfill Jordan’s energy needs, but also as an economic asset that will ‎finance Jordan’s nuclear program. The average uranium concentration of 236 soil samples using ICP-Mass (inductively coupled plasma mass spectrometry was found to be 109 parts per million (ppm. Results analysis revealed a wide range of 1066 ppm for uranium concentration, and a median of 41 ppm uranium. The measurements frequency distribution indicates that 72% of samples measured had a uranium content of less than 100 ppm, a concentration that characterizes overburden and tailings quality, rather than minable reserves. This paper presents and evaluates the concentration of uranium in central Jordan, being the most promising area with the highest radioactive anomalies in Jordan.

  9. Uranium in groundwater — Fertilizers versus geogenic sources

    Energy Technology Data Exchange (ETDEWEB)

    Liesch, Tanja, E-mail: tanja.liesch@kit.edu; Hinrichsen, Sören; Goldscheider, Nico

    2015-12-01

    Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N = 1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10 μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater. - Highlights: • Uranium concentrations in groundwater in Southwest Germany mainly depend on geology. • Only 1.6% of 1935 samples exceed the German legal limit for drinking water of 10 μg/L. • The percentage of positive uranium detections (> 0.5 μg/L) is higher in agricultural areas. • Phosphate fertilizers cause significant increase of uranium in groundwater at low concentration levels.

  10. Correlation of radioactive-waste-treatment costs and the environmental impact of waste effluents in the nuclear fuel cycle: conversion of yellow cake to uranium hexafluoride. Part II. The solvent extraction-fluorination process

    Energy Technology Data Exchange (ETDEWEB)

    Sears, M.B.; Etnier, E.L.; Hill, G.S.; Patton, B.D.; Witherspoon, J.P.; Yen, S.N.

    1983-03-01

    A cost/benefit study was made to determine the cost and effectiveness of radioactive waste (radwaste) treatment systems for decreasing the release of radioactive materials and chemicals from a model uranium hexafluoride (UF/sub 6/) production plant using the solvent extraction-fluorination process, and to evaluate the radiological impact (dose commitment) of the release materials on the environment. The model plant processes 10,000 metric tons of uranium per year. Base-case waste treatment is the minimum necessary to operate the process. Effluents meet the radiological requirements listed in the Code of Federal Regulations, Title 10, Part 20 (10 CFR 20), Appendix B, Table II, but may not be acceptable chemically at all sites. Additional radwaste treatment techniques are applied to the base-case plant in a series of case studies to decrease the amounts of radioactive materials released and to reduce the amounts of radioactive materials released and to reduce the radiological dose commitment to the population in the surrounding area. The costs for the added waste treatment operations and the corresponding dose committment are correlated with the annual cost for treatment of the radwastes. The status of the radwaste treatment methods used in the case studies is discussed. Much of the technology used in the advanced cases will require development and demonstration, or else is proprietary and unavailable for immediate use. The methodology and assumptions for the radiological doses are found in ORNL-4992.

  11. Soil Properties in Natural Forest Destruction and Conversion to Agricultural Land,in Gunung Leuser National Park, North Sumatera Province

    Directory of Open Access Journals (Sweden)

    Basuki Wasis

    2012-12-01

    Full Text Available Destruction of the Gunung Leuser National Park area of North Sumatera Province through land clearing and land cover change from natural forest to agricultural land. Less attention to land use and ecosystem carrying capacity of the soil can cause soil degradation and destruction of flora, fauna, and wildlife habitat destruction. Environmental damage will result in a national park wild life will come out of the conservation area and would damage the agricultural community. Soil sampling conducted in purposive sampling in natural forest and agricultural areas.  Observation suggest that damage to the natural forest vegetation has caused the soil is not protected so that erosion has occurred. Destruction of natural forest into agricultural are as has caused damage to soil physical properties, soil chemical properties, and biological soil properties significantly. Forms of soil degradation caused by the destruction of natural forests, which is an increase in soil density (density Limbak by 103%, a decrease of 93% organic C and soil nitrogen decreased by 81%. The main factors causing soil degradation is the reduction of organic matter and soil erosion due to loss of natural forest vegetation.  Criteria for soil degradation in Governance Regulation Number 150/2000 can be used to determine the extent of soil degradation in natural forest ecosystems.Keywords: Gunung Leuser National Park, natural forest, agricultural land, land damage, soil properties

  12. Rare earth elements (REE) as natural and applied tracers in the catchment area of Gessental valley, former uranium mining area of Eastern Thuringia, Germany

    Science.gov (United States)

    Buechel, G.; Merten, D.; Geletneky, J. W.; Kothe, E.

    2003-04-01

    Between 1947 and 1990 about 113.000 t of uranium were excavated at the former uranium mining site of Ronneburg (Eastern Thuringia, Germany). The legacy consists of more than 200 million m^3 of metasedimentary rocks rich in organic matter, sulfides and heavy metals originally deposited in mining heaps at the surface. The metasedimentary rocks formed under anoxic conditions about a 400 Mio. years ago are now exposed to oxic conditions. The oxidation of markasite and pyrite results in the formation of H_2SO_4. The formation of acid mine drainage (AMD) leads to high concentrations of uranium, rare earth elements (REE) and other heavy metals in surface water, seepage water and groundwater. This mobilization is due to alteration enhanced by high microbial activity and low pH. The tolerance mechanisms towards heavy metal pollution of soil substrate and surface/groundwater has allowed the selection of microbes which have, e.g. specific transporter genes and which are associated to plants in symbiotic interactions like mycorrhiza. In order to follow the processes linking alteration of metasedimentary rocks to biological systems the use of tracers is needed. One group of such tracers occuring in high concentrations in the water phase at the Ronneburg mining site are the REE (La-Lu) which are featured by very similar chemical behaviour. They show smooth but continuous variations of their chemical behaviour as a function of atomic number. For seepage water of the waste rock dump Nordhalde - sampled over a period of two years - the shale normalized REE patterns show enrichment of heavy REE and only minor variations, although the concentration differs. At sampling points in the surface water and in groundwater rather similar REE patterns were observed. Thus, REE can be used as tracers to identify diffuse inflow of REE-rich acid mine drainage of the dumps into the creek and the sediments. The absolute concentrations of REE in the creek and in ground water are up to 1000 times

  13. Long-term organic-inorganic fertilization ensures great soil productivity and bacterial diversity after natural-to-agricultural ecosystem conversion.

    Science.gov (United States)

    Xun, Weibing; Xu, Zhihui; Li, Wei; Ren, Yi; Huang, Ting; Ran, Wei; Wang, Boren; Shen, Qirong; Zhang, Ruifu

    2016-09-01

    Natural ecosystems comprise the planet's wild plant and animal resources, but large tracts of land have been converted to agroecosystems to support the demand for agricultural products. This conversion limits the number of plant species and decreases the soil biological diversity. Here we used high-throughput 16S rRNA gene sequencing to evaluate the responses of soil bacterial communities in long-term converted and fertilized red soils (a type of Ferralic Cambisol). We observed that soil bacterial diversity was strongly affected by different types of fertilization management. Oligotrophic bacterial taxa demonstrated large relative abundances in chemically fertilized soil, whereas copiotrophic bacterial taxa were found in large relative abundances in organically fertilized and fallow management soils. Only organic-inorganic fertilization exhibited the same local taxonomic and phylogenetic diversity as that of a natural ecosystem. However, the independent use of organic or inorganic fertilizer reduced local taxonomic and phylogenetic diversity and caused biotic homogenization. This study demonstrated that the homogenization of bacterial communities caused by natural-to-agricultural ecosystem conversion can be mitigated by employing rational organic-inorganic fertilization management.

  14. Investigating the thermodynamic stability of Bacillus subtilis spore-uranium(VI) adsorption though surface complexation modeling

    Science.gov (United States)

    Harrold, Z.; Hertel, M.; Gorman-Lewis, D.

    2012-12-01

    Dissolved uranium speciation, mobility, and remediation are increasingly important topics given continued and potential uranium (U) release from mining operations and nuclear waste. Vegetative bacterial cell surfaces are known to adsorb uranium and may influence uranium speciation in the environment. Previous investigations regarding U(VI) adsorption to bacterial spores, a differentiated and dormant cell type with a tough proteinaceous coat, include U adsorption affinity and XAFS data. We investigated the thermodynamic stability of aerobic, pH dependent uranium adsorption to bacterial spore surfaces using purified Bacillus subtilis spores in solution with 5ppm uranium. Adsorption reversibility and kinetic experiments indicate that uranium does not precipitate over the duration of the experiments and equilibrium is reached within 20 minutes. Uranium-spore adsorption edges exhibited adsorption at all pH measured between 2 and 10. Maximum adsorption was achieved around pH 7 and decreased as pH increased above 7. We used surface complexation modeling (SCM) to quantify uranium adsorption based on balanced chemical equations and derive thermodynamic stability constants for discrete uranium-spore adsorption reactions. Site specific thermodynamic stability constants provide insight on interactions occurring between aqueous uranium species and spore surface ligands. The uranium adsorption data and SCM parameters described herein, also provide a basis for predicting the influence of bacterial spores on uranium speciation in natural systems and investigating their potential as biosorption agents in engineered systems.

  15. Highly Sensitive and Selective Uranium Detection in Natural Water Systems Using a Luminescent Mesoporous Metal-Organic Framework Equipped with Abundant Lewis Basic Sites: A Combined Batch, X-ray Absorption Spectroscopy, and First Principles Simulation Investigation.

    Science.gov (United States)

    Liu, Wei; Dai, Xing; Bai, Zhuanling; Wang, Yanlong; Yang, Zaixing; Zhang, Linjuan; Xu, Lin; Chen, Lanhua; Li, Yuxiang; Gui, Daxiang; Diwu, Juan; Wang, Jianqiang; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

    2017-04-04

    Uranium is not only a strategic resource for the nuclear industry but also a global contaminant with high toxicity. Although several strategies have been established for detecting uranyl ions in water, searching for new uranium sensor material with great sensitivity, selectivity, and stability remains a challenge. We introduce here a hydrolytically stable mesoporous terbium(III)-based MOF material compound 1, whose channels are as large as 27 Å × 23 Å and are equipped with abundant exposed Lewis basic sites, the luminescence intensity of which can be efficiently and selectively quenched by uranyl ions. The detection limit in deionized water reaches 0.9 μg/L, far below the maximum contamination standard of 30 μg/L in drinking water defined by the United States Environmental Protection Agency, making compound 1 currently the only MOF material that can achieve this goal. More importantly, this material exhibits great capability in detecting uranyl ions in natural water systems such as lake water and seawater with pH being adjusted to 4, where huge excesses of competing ions are present. The uranyl detection limits in Dushu Lake water and in seawater were calculated to be 14.0 and 3.5 μg/L, respectively. This great detection capability originates from the selective binding of uranyl ions onto the Lewis basic sites of the MOF material, as demonstrated by synchrotron radiation extended X-ray adsorption fine structure, X-ray adsorption near edge structure, and first principles calculations, further leading to an effective energy transfer between the uranyl ions and the MOF skeleton.

  16. Determination of Lithium,boron,zirconium and niobium in natural uranium dioxde by ICP-AES%ICP-AES法测定天然二氧化铀中锂、硼、锆、铌

    Institute of Scientific and Technical Information of China (English)

    李洪; 李强; 杨箭; 贺艳红

    2011-01-01

    采用TBP萃淋树脂铀基体分离-ICP-AES法测定天然二氧化铀中锂、硼、锆、铌4种杂质元素的含量,当试样平行测定数量为6个时,锂、硼、锆、铌测定结果相对标准偏差依次为0.8%、4.7%、4.9%、1.1%,加标回收率锂为91.9%-96.8%,硼为95.0%-106.5%,锆为93.4%-103.5%,铌为97.8%-103.9%.方法快捷,测定方法满足工厂二氧化铀产品验收质量分析要求.%The contents of four impurity elements such as lithium,boron,zirconium and niobium in natural uranium dioxide were determined by TBP levextrel resin uranium matrix separation-ICP-AES method. Relative standard deviations (n = 6) for four elements were 0. 8% for lithium, 4. 7% for boron,7.9% for zirconium, 1. 1% for niobium. The recovery rates were 91. 9%-96. 8% for lithium, 95. 0%-106. 5% for boron, 93. 4%-103. 5% for zirconium, 97. 8%-103. 9% for niobium. The method is fast,and the results can meet requirements.

  17. Uranium deposits of the world. Europe

    Energy Technology Data Exchange (ETDEWEB)

    Dahlkamp, Franz J.

    2016-07-01

    Uranium Deposits of the World, in three volumes, comprises an unprecedented compilation of data and descriptions of the uranium regions in Asia, USA, Latin America and Europe structured by countries. With this third, the Europe volume, Uranium Deposits of the World presents the most extensive data collection of the set. It covers about 140 uranium regions in more than 20 European countries with nearly 1000 mentioned uranium deposits. Each country and region receives an analytical overview followed by the geologically- and economically-relevant synopsis of the individual regions and fields. The presentations are structured in three major sections: (a) location and magnitude of uranium regions, districts, and deposits, (b) principal features of regions and districts, and (c) detailed characteristics of selected ore fields and deposits. This includes sections on geology, alteration, mineralization, shape and dimensions of deposits, isotopes data, ore control and recognition criteria, and metallogenesis. Beside the main European uranium regions, for example in the Czech Republic, Eastern Germany, France, the Iberian Peninsula or Ukraine, also small regions an districts to the point of singular occurrences of interest are considered. This by far the most comprehensive presentation of European uranium geology and mining would not be possible without the author's access to extensive information covering the countries of the former Eastern Bloc states, which was partly not previously available. Abundantly illustrated with information-laden maps and charts throughout, this reference work is an indispensable tool for geologists, mining companies, government agencies, and others with an interest in European key natural resources. A great help for the reader's orientation are the substantial bibliography of uranium-related publications and the indices, latter containing about 3900 entries in the geographical part alone. The three volumes of Uranium Deposits of the

  18. Mica surfaces stabilize pentavalent uranium.

    Science.gov (United States)

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

    2005-05-02

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

  19. Correlation of radioactive waste treatment costs and the environmental impact of waste effluents in the nuclear fuel cycle: conversion of yellow cake to uranium hexafluoride. Part I. The fluorination-fractionation process

    Energy Technology Data Exchange (ETDEWEB)

    Sears, M.B.; Blanco, R.E.; Finney, B.C.; Hill, G.S.; Moore, R.E.; Witherspoon, J.P.

    1977-07-01

    A cost/benefit study was made to determine the cost and effectiveness of radioactive waste (radwaste) treatment systems for decreasing the release of radioactive materials and chemicals from a model uranium hexafluoride (UF/sub 6/) production plant using the fluorination-fractionation (dry hydrofluor) process, and to evaluate the radiological impact (dose commitment) of the released materials on the environment. This study is designed to assist in defining the term as low as is reasonably achievable (ALARA) in relation to limiting the release of radioactive materials from nuclear facilities. The model plant processes 10,000 metric tons of uranium per year. Base-case waste treatment is the minimum necessary to operate the process. Effluents meet the radiological requirements listed in the Code of Federal Regulations, Title 10, Part 20 (10 CFR 20), Appendix B, Table II, but may not be acceptable chemically at all sites. Additional radwaste treatment techniques are applied to the base-case plant in a series of case studies to decrease the amounts of radioactive materials released and to reduce the radiological dose commitment to the population in the surrounding area. The costs for the added waste treatment operations and the corresponding dose commitment are calculated for each case. In the final analysis, radiological dose is plotted vs the annual cost for treatment of the radwastes. The status of the radwaste treatment methods used in the case studies is discussed. Much of the technology used in the advanced cases will require development and demonstration or else is proprietary and unavailable for immediate use. The methodology and assumptions for the radiological doses are found in ORNL-4992.

  20. Conversational sensing

    Science.gov (United States)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  1. Occupational exposures to uranium: processes, hazards, and regulations

    Energy Technology Data Exchange (ETDEWEB)

    Stoetzel, G.A.; Fisher, D.R.; McCormack, W.D.; Hoenes, G.R.; Marks, S.; Moore, R.H.; Quilici, D.G.; Breitenstein, B.D.

    1981-04-01

    The United States Uranium Registry (USUR) was formed in 1978 to investigate potential hazards from occupational exposure to uranium and to assess the need for special health-related studies of uranium workers. This report provides a summary of Registry work done to date. The history of the uranium industry is outlined first, and the current commercial uranium industry (mining, milling, conversion, enrichment, and fuel fabrication) is described. This description includes information on basic processes and areas of greatest potential radiological exposure. In addition, inactive commercial facilities and other uranium operations are discussed. Regulation of the commercial production industry for uranium fuel is reported, including the historic development of regulations and the current regulatory agencies and procedures for each phase of the industry. A review of radiological health practices in the industry - facility monitoring, exposure control, exposure evaluation, and record-keeping - is presented. A discussion of the nonradiological hazards of the industry is provided, and the final section describes the tissue program developed as part of the Registry.

  2. Demand of natural uranium to satisfy the requirements of nuclear fuel of new nuclear power plants in Mexico; Demanda de uranio natural para satisfacer los requerimientos de combustible nuclear de nuevas centrales nucleares en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez S, J. R.; Rios, M. del C.; Alonso, G.; Palacios H, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: jrrs@nuclear.inin.mx

    2008-07-01

    Due to the expectation of that in Mexico new plants of nuclear energy could be installed, turns out from the interest to evaluate the uranium requirements to operate those plants and to also evaluate if the existing reserves in the country could be sufficient to satisfy that demand. Three different scenes from nuclear power plant expansion for the country are postulated here that are desirable for the diversification of generation technologies. The first scene considers a growth in the generation by nuclear means of two reactors of type ABWR that could enter operation by years 2015 and 2020, in the second considers the installation of four reactors but as of 2015 and new every 5 years, in the scene of high growth considers the installation of 6 reactors of the same type that in the other scenes, settling one every three years as of 2015. The results indicate that the uranium reserves could be sufficient to only maintain in operation to one of the reactors proposed by the time of their useful life. (Author)

  3. Natural uranium and strontium isotope tracers of water sources and surface water-groundwater interactions in arid wetlands: Pahranagat Valley, Nevada, USA

    Science.gov (United States)

    Paces, James B.; Wurster, Frederic C.

    2014-01-01

    Near-surface physical and chemical process can strongly affect dissolved-ion concentrations and stable isotope compositions of water in wetland settings, especially under arid climate conditions. In contrast, heavy radiogenic isotopes of strontium (87Sr/86Sr) and uranium (234U/238U) remain largely unaffected and can be used to help identify unique signatures from different sources and quantify end-member mixing that would otherwise be difficult to determine. The utility of combined Sr and U isotopes are demonstrated in this study of wetland habitats on the Pahranagat National Wildlife Refuge, which depend on supply from large-volume springs north of the Refuge, and from small-volume springs and seeps within the Refuge. Water budgets from these sources have not been quantified previously. Evaporation, transpiration, seasonally variable surface flow, and water management practices complicate the use of conventional methods for determining source contributions and mixing relations. In contrast, 87Sr/86Sr and 234U/238U remain unfractionated under these conditions, and compositions at a given site remain constant. Differences in Sr- and U-isotopic signatures between individual sites can be related by simple two- or three-component mixing models. Results indicate that surface flow constituting the Refuge’s irrigation source consists of a 65:25:10 mixture of water from two distinct regionally sourced carbonate aquifer springs, and groundwater from locally sourced volcanic aquifers. Within the Refuge, contributions from the irrigation source and local groundwater are readily determined and depend on proximity to those sources as well as water management practices.

  4. Uranium Location Database

    Data.gov (United States)

    U.S. Environmental Protection Agency — A GIS compiled locational database in Microsoft Access of ~15,000 mines with uranium occurrence or production, primarily in the western United States. The metadata...

  5. Uranium in alkaline rocks

    Energy Technology Data Exchange (ETDEWEB)

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

    1978-04-01

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

  6. Uranium XAFS analysis of kidney from rats exposed to uranium

    Science.gov (United States)

    Kitahara, Keisuke; Numako, Chiya; Terada, Yasuko; Nitta, Kiyohumi; Homma-Takeda, Shino

    2017-01-01

    The kidney is the critical target of uranium exposure because uranium accumulates in the proximal tubules and causes tubular damage, but the chemical nature of uranium in kidney, such as its chemical status in the toxic target site, is poorly understood. Micro-X-ray absorption fine-structure (µXAFS) analysis was used to examine renal thin sections of rats exposed to uranyl acetate. The U L III-edge X-ray absorption near-edge structure spectra of bulk renal specimens obtained at various toxicological phases were similar to that of uranyl acetate: their edge position did not shift compared with that of uranyl acetate (17.175 keV) although the peak widths for some kidney specimens were slightly narrowed. µXAFS measurements of spots of concentrated uranium in the micro-regions of the proximal tubules showed that the edge jump slightly shifted to lower energy. The results suggest that most uranium accumulated in kidney was uranium (VI) but a portion might have been biotransformed in rats exposed to uranyl acetate. PMID:28244440

  7. Characteristic Analysis for the Recycled Uranium of the Pyroprocess

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Je; Ryu, Ho Jin; Na, Sang Ho; Kang, Kweon Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-11-15

    In order to recover uranium and TRU from spent nuclear fuels, a pyroprocessing has been developed through a dry and metallurgical reprocess technology using a series of electrolyses such as an electro-reduction, an electro-refining, and an electro-winning. When the spent fuel is being fed into the pyroprocess, most of the uranium is gathered in metallic form around a solid cathode during an electro-refining process. It is expected that the recovered uranium will be sent to a spent fuel storage site after converting it into a metal ingot form to reduce its storage space and transportation burden. However, the weight percent of U-235 in the recovered uranium is about 0.9 wt% and it is sufficiently re-utilized in a heavy water reactor which uses a natural uranium fuel. The reuse of recovered uranium will bring not only a huge economical profit and save of uranium resources but also an alleviation of burden on the management and disposal of the spent fuel. A previous research on recycling of recovered uranium was carried out and most of the recovered uranium was assumed to be imported from abroad at that time. The preliminary results showed there is a sufficient possibility to recycle recovered uranium in terms of a reactor's characteristics as well as the fuel performance. And the DUPIC (direct use of spent pressurized water reactor fuel into CANDU reactor) program has also been performed and demonstrated the fundamental technologies. The recovered uranium from a pyroprocess contains some TRU as an impurity and it will exhibit a slightly different behavior from the previous recycling options. In this report, the reactor's characteristics including discharge burnup are investigated based on the lattice calculations which are performed for the CANFELX bundle.

  8. Assistance and Feedback Mechanism in an Intelligent Tutoring System for Teaching Conversion of Natural Language into Logic

    Science.gov (United States)

    Perikos, Isidoros; Grivokostopoulou, Foteini; Hatzilygeroudis, Ioannis

    2017-01-01

    Logic as a knowledge representation and reasoning language is a fundamental topic of an Artificial Intelligence (AI) course and includes a number of sub-topics. One of them, which brings difficulties to students to deal with, is converting natural language (NL) sentences into first-order logic (FOL) formulas. To assist students to overcome those…

  9. Environmental consequences of uranium atmospheric releases from fuel cycle facility: II. The atmospheric deposition of uranium and thorium on plants.

    Science.gov (United States)

    Pourcelot, L; Masson, O; Renaud, P; Cagnat, X; Boulet, B; Cariou, N; De Vismes-Ott, A

    2015-03-01

    Uranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely (238)U/(232)Th and (230)Th/(232)Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and (230)Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6 × 10(-3) and 5.0 × 10(-3) m s(-1), respectively.

  10. Metabolic flux analysis model for optimizing xylose conversion into ethanol by the natural C5-fermenting yeast Candida shehatae.

    Science.gov (United States)

    Bideaux, Carine; Montheard, Julie; Cameleyre, Xavier; Molina-Jouve, Carole; Alfenore, Sandrine

    2016-02-01

    A metabolic flux analysis (MFA) model was developed to optimize the xylose conversion into ethanol using Candida shehatae strain. This metabolic model was compartmented and constructed with xylose as carbon substrate integrating the enzymatic duality of the first step of xylose degradation via an algebraic coefficient. The model included the pentose phosphate pathway, glycolysis, synthesis of major metabolites like ethanol, acetic acid and glycerol, the tricarboxylic acid cycle as well as the respiratory chain, the cofactor balance, and the maintenance. The biomass composition and thus production were integrated considering the major biochemical synthesis reactions from monomers to each constitutive macromolecule (i.e., proteins, lipids, polysaccharides, nucleic acids). The construction of the model resulted into a 122-linear equation system to be resolved. A first experiment allowed was to verify the accuracy of the model by comparing calculated and experimental data. The metabolic model was utilized to determine the theoretical yield taking into account oxido-reductive balance and to optimize ethanol production. The maximal theoretical yield was calculated at 0.62 Cmolethanol/Cmolxylose for an oxygen requirement of 0.33 moloxygen/molxylose linked to the cofactors of the xylose reductase. Cultivations in chemostat mode allowed the fine tuning of both xylose and oxygen uptakes and showed that lower was the oxygen/xylose ratio, higher was the ethanol production yield. The best experimental ethanol production yield (0.51 Cmolethanol/Cmolxylose) was obtained for an oxygen supply of 0.47 moloxygen/molxylose.

  11. Selective Extraction of Uranium from Liquid or Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-31

    Current liquid-liquid extraction processes used in recycling irradiated nuclear fuel rely on (1) strong nitric acid to dissolve uranium oxide fuel, and (2) the use of aliphatic hydrocarbons as a diluent in formulating the solvent used to extract uranium. The nitric acid dissolution process is not selective. It dissolves virtually the entire fuel meat which complicates the uranium extraction process. In addition, a solvent washing process is used to remove TBP degradation products, which adds complexity to the recycling plant and increases the overall plant footprint and cost. A liquid or supercritical carbon dioxide (l/sc -CO2) system was designed to mitigate these problems. Indeed, TBP nitric acid complexes are highly soluble in l/sc -CO2 and are capable of extracting uranium directly from UO2, UO3 and U3O8 powders. This eliminates the need for total acid dissolution of the irradiated fuel. Furthermore, since CO2 is easily recycled by evaporation at room temperature and pressure, it eliminates the complex solvent washing process. In this report, we demonstrate: (1) A reprocessing scheme starting with the selective extraction of uranium from solid uranium oxides into a TBP-HNO3 loaded Sc-CO2 phase, (2) Back extraction of uranium into an aqueous phase, and (3) Conversion of recovered purified uranium into uranium oxide. The purified uranium product from step 3 can be disposed of as low level waste, or mixed with enriched uranium for use in a reactor for another fuel cycle. After an introduction on the concept and properties of supercritical fluids, we first report the characterization of the different oxides used for this project. Our extraction system and our online monitoring capability using UV-Vis absorbance spectroscopy directly in sc-CO2 is then presented. Next, the uranium extraction efficiencies and kinetics is demonstrated for different oxides and under different physical and chemical conditions: l/sc -CO2 pressure and temperature, TBP/HNO3 complex used

  12. Long-term ecological effects of exposure to uranium

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, W.C.; Miera, F.R. Jr.

    1976-03-01

    The consequences of releasing natural and depleted uranium to terrestrial ecosystems during development and testing of depleted uranium munitions were investigated. At Eglin Air Force Base, Florida, soil at various distances from armor plate target butts struck by depleted uranium penetrators was sampled. The upper 5 cm of soil at the target bases contained an average of 800 ppM of depleted uranium, about 30 times as much as soil at 5- to 10-cm depth, indicating some vertical movement of depleted uranium. Samples collected beyond about 20 m from the targets showed near-background natural uranium levels, about 1.3 +- 0.3 ..mu..g/g or ppM. Two explosives-testing areas at the Los Alamos Scientific Laboratory (LASL) were selected because of their use history. E-F Site soil averaged 2400 ppM of uranium in the upper 5 cm and 1600 ppM at 5-10 cm. Lower Slobovia Site soil from two subplots averaged about 2.5 and 0.6 percent of the E-F Site concentrations. Important uranium concentration differences with depth and distance from detonation points were ascribed to the different explosive tests conducted in each area. E-F Site vegetation samples contained about 320 ppM of uranium in November 1974 and about 125 ppM in June 1975. Small mammals trapped in the study areas in November contained a maximum of 210 ppM of uranium in the gastrointestinal tract contents, 24 ppM in the pelt, and 4 ppM in the remaining carcass. In June, maximum concentrations were 110, 50, and 2 ppM in similar samples and 6 ppM in lungs. These data emphasized the importance of resuspension of respirable particles in the upper few millimeters of soil as a contamination mechanism for several components of the LASL ecosystem.

  13. Organic Rankine Cycle for Residual Heat to Power Conversion in Natural Gas Compressor Station. Part I: Modelling and Optimisation Framework

    Science.gov (United States)

    Chaczykowski, Maciej

    2016-06-01

    Basic organic Rankine cycle (ORC), and two variants of regenerative ORC have been considered for the recovery of exhaust heat from natural gas compressor station. The modelling framework for ORC systems has been presented and the optimisation of the systems was carried out with turbine power output as the variable to be maximized. The determination of ORC system design parameters was accomplished by means of the genetic algorithm. The study was aimed at estimating the thermodynamic potential of different ORC configurations with several working fluids employed. The first part of this paper describes the ORC equipment models which are employed to build a NLP formulation to tackle design problems representative for waste energy recovery on gas turbines driving natural gas pipeline compressors.

  14. Depleted uranium storage and disposal trade study: Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Hightower, J.R.; Trabalka, J.R.

    2000-02-01

    The objectives of this study were to: identify the most desirable forms for conversion of depleted uranium hexafluoride (DUF6) for extended storage, identify the most desirable forms for conversion of DUF6 for disposal, evaluate the comparative costs for extended storage or disposal of the various forms, review benefits of the proposed plasma conversion process, estimate simplified life-cycle costs (LCCs) for five scenarios that entail either disposal or beneficial reuse, and determine whether an overall optimal form for conversion of DUF6 can be selected given current uncertainty about the endpoints (specific disposal site/technology or reuse options).

  15. Uranium biomineralization by a metal resistant Pseudomonas aeruginosa strain isolated from contaminated mine waste

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Sangeeta [Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302 (India); Sar, Pinaki, E-mail: sarpinaki@yahoo.com [Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302 (India)

    2011-02-15

    Uranium biomineralization by a metal-resistant Pseudomonas aeruginosa strain isolated from uranium mine waste was characterized for its potential in bioremediation. Uranium resistance, its cellular localization and chemical nature of uranium-bacteria interaction were elucidated. Survival and uranium biomineralization from mine water were investigated using microcosm experiments. The selected bacterium showed U resistance and accumulation (maximum of 275 mg U g{sup -1} cell dry wt.) following incubation in 100 mg U L{sup -1}, pH 4.0, for 6 h. Transmission electron microscopy and X-ray diffraction analyses revealed that bioaccumulated uranium was deposited within the cell envelope as needle shaped U-phosphate compounds that attain crystallinity only at pH 4.0. A synergistic involvement of deprotonated phosphate and carboxyl moieties in facilitating bioprecipitation of uranium was evident from FTIR analysis. Based on these findings we attribute the localized U sequestration by this bacterium as innocuous complex to its possible mechanism of uranium resistance. Microcosm data confirmed that the strain can remove soluble uranium (99%) and sequester it as U oxide and phosphate minerals while maintaining its viability. The study showed that indigenous bacteria from contaminated site that can survive uranium and other heavy metal toxicity and sequester soluble uranium as biominerals could play important role in uranium bioremediation.

  16. Teratogenicity of depleted uranium aerosols: A review from an epidemiological perspective

    OpenAIRE

    Panikkar Bindu; Brugge Doug; Hindin Rita

    2005-01-01

    Abstract Background Depleted uranium is being used increasingly often as a component of munitions in military conflicts. Military personnel, civilians and the DU munitions producers are being exposed to the DU aerosols that are generated. Methods We reviewed toxicological data on both natural and depleted uranium. We included peer reviewed studies and gray literature on birth malformations due to natural and depleted uranium. Our approach was to assess the "weight of evidence" with respect to...

  17. Uranium contamination due to nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A.; Vera Tome, F.; Diaz Bejarano, J.; Garcia Aparicio, A. (Univ. de Extremadura, Badajoz (Spain). Dept. de Fisica)

    1992-01-01

    Measurements of uranium isotopes and their daughters in the natural series were performed in the cooling reservoirs and their neighborhood of two nuclear power plants, [alpha] and [gamma] spectrometry of samples were used to measure the natural and artificial radionuclides. The nuclear power plants are in the southwest of Spain and one of them has been in operation since 1982, the other plant is in the construction phase. We compare the results obtained for the two sites. (orig.).

  18. Variably saturated flow and multicomponent biogeochemical reactive transport modeling of a uranium bioremediation field experiment.

    Science.gov (United States)

    Yabusaki, Steven B; Fang, Yilin; Williams, Kenneth H; Murray, Christopher J; Ward, Andy L; Dayvault, Richard D; Waichler, Scott R; Newcomer, Darrell R; Spane, Frank A; Long, Philip E

    2011-11-01

    Three-dimensional, coupled variably saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport and biogeochemical reactions controlling uranium behavior under pulsed acetate amendment, seasonal water table variation, spatially variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. While the simulation of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado was generally consistent with behaviors identified in previous field experiments at the Rifle IFRC site, the additional process and property detail provided several new insights. A principal conclusion from this work is that uranium bioreduction is most effective when acetate, in excess of the sulfate-reducing bacteria demand, is available to the metal-reducing bacteria. The inclusion of an initially small population of slow growing sulfate-reducing bacteria identified in proteomic analyses led to an additional source of Fe(II) from the dissolution of Fe(III) minerals promoted by biogenic sulfide. The falling water table during the experiment significantly reduced the saturated thickness of the aquifer and resulted in reactants and products, as well as unmitigated uranium, in the newly unsaturated vadose zone. High permeability sandy gravel structures resulted in locally high flow rates in the vicinity of injection wells that increased acetate dilution. In downgradient locations, these structures created preferential flow paths for acetate delivery that enhanced local zones of TEAP reactivity and subsidiary reactions. Conversely, smaller transport rates associated with the lower permeability lithofacies (e.g., fine) and vadose zone were shown to limit acetate access and reaction. Once accessed by acetate, however, these same zones limited subsequent acetate dilution and provided longer residence times that resulted

  19. Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume January 2011 to January 2012

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark S.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammond, Glenn E.; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Zheng, Chunmiao

    2012-03-05

    The Integrated Field Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex subsurface biogeochemical setting where groundwater and riverwater interact. A series of forefront science questions on reactive mass transfer motivates research. These questions relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated biogeochemical system. The project was initiated in February 2007, with CY 2007, CY 2008, CY 2009, and CY 2010 progress summarized in preceding reports. A project peer review was held in March 2010, and the IFRC project acted upon all suggestions and recommendations made in consequence by reviewers and SBR/DOE. These responses have included the development of 'Modeling' and 'Well-Field Mitigation' plans that are now posted on the Hanford IFRC web-site, and modifications to the IFRC well-field completed in CY 2011. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2011 including: (i) well modifications to eliminate well-bore flows, (ii) hydrologic testing of the modified well-field and upper aquifer, (iii) geophysical monitoring of winter precipitation infiltration through the U-contaminated vadose zone and spring river water intrusion to the IFRC, (iv) injection experimentation to probe the lower vadose zone and to evaluate the transport behavior of high U concentrations, (v) extended passive monitoring during the period of water table rise and fall, and (vi) collaborative down-hole experimentation with the PNNL SFA on the biogeochemistry of the 300 A Hanford

  20. Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark E.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammon, Glenn; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Ward, Anderson L.; Zheng, Chunmiao

    2010-02-01

    The Integrated Field-Scale Subsurface Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex hydrogeologic setting where groundwater and riverwater interact. A series of forefront science questions on mass transfer are posed for research which relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated system. The project was initiated in February 2007, with CY 2007 and CY 2008 progress summarized in preceding reports. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2009 with completion of extensive laboratory measurements on field sediments, field hydrologic and geophysical characterization, four field experiments, and modeling. The laboratory characterization results are being subjected to geostatistical analyses to develop spatial heterogeneity models of U concentration and chemical, physical, and hydrologic properties needed for reactive transport modeling. The field experiments focused on: (1) physical characterization of the groundwater flow field during a period of stable hydrologic conditions in early spring, (2) comprehensive groundwater monitoring during spring to characterize the release of U(VI) from the lower vadose zone to the aquifer during water table rise and fall, (3) dynamic geophysical monitoring of salt-plume migration during summer, and (4) a U reactive tracer experiment (desorption) during the fall. Geophysical characterization of the well field was completed using the down-well Electrical Resistance Tomography (ERT) array, with results subjected to robust

  1. Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume January 2010 to January 2011

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark S.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammond, Glenn E.; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Ward, Anderson L.; Zheng, Chunmiao

    2011-02-01

    The Integrated Field Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex subsurface hydrogeologic setting where groundwater and riverwater interact. A series of forefront science questions on reactive mass transfer focus research. These questions relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated system. The project was initiated in February 2007, with CY 2007, CY 2008, and CY 2009 progress summarized in preceding reports. A project peer review was held in March 2010, and the IFRC project has responded to all suggestions and recommendations made in consequence by reviewers and SBR/DOE. These responses have included the development of “Modeling” and “Well-Field Mitigation” plans that are now posted on the Hanford IFRC web-site. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2010 including the quantification of well-bore flows in the fully screened wells and the testing of means to mitigate them; the development of site geostatistical models of hydrologic and geochemical properties including the distribution of U; developing and parameterizing a reactive transport model of the smear zone that supplies contaminant U to the groundwater plume; performance of a second passive experiment of the spring water table rise and fall event with a associated multi-point tracer test; performance of downhole biogeochemical experiments where colonization substrates and discrete water and gas samplers were deployed to the lower aquifer zone; and modeling of past injection experiments for

  2. Conversational Dominance.

    Science.gov (United States)

    Esau, Helmut; Poth, Annette

    Details of conversational behavior can often not be interpreted until the social interaction, including the rights and obligations of the participants, their intent, the topic, etc., has been defined. This paper presents a model of conversation in which the conversational image a person presents in a given conversational situation is a function of…

  3. Fabrication of Natural Uranium UO2 Disks (Phase II): Texas A&M Work for Others Summary Document

    Energy Technology Data Exchange (ETDEWEB)

    Gerczak, Tyler J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Baldwin, Charles A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schmidlin, Joshua E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Henry, Jr, John James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-28

    The steps to fabricate natural UO2 disks for an irradiation campaign led by Texas A&M University are outlined. The process was initiated with stoichiometry adjustment of parent, U3O8 powder. The next stage of sample preparation involved exploratory pellet pressing and sintering to achieve the desired natural UO2 pellet densities. Ideal densities were achieved through the use of a bimodal powder size blend. The steps involved with disk fabrication are also presented, describing the coring and thinning process executed to achieve final dimensionality.

  4. Radiochemical separation of thorium from the natural uranium irradiated by 60MeV/u 18O ions%60MeV/u 18O离子同天然铀反应 钍的放化分离

    Institute of Scientific and Technical Information of China (English)

    杨维凡; 袁双贵; 马桃桃; 熊兵; 徐岩冰; 李宗伟; 何建军

    2001-01-01

    用1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5(PMBP)作萃取剂,234Th为示踪剂,对在HNO3介质中用PMBP-苯萃取钍的条件实验进行了研究。在条件实验的基础上提出了一个从中能18O离子照过的天然铀样品中简便、快速地分离钍的化学流程。钍样品的γ射线谱显示该流程能去除绝大多数产物元素,特别是U、Ce和I的沾污。%The experimental conditions for the extraction of thorium by using PMBP as extractant and 234Th as tracer in the nitric acid solution were investigated. Based on the experiments, a chemical procedure used for rapidly separating thorium from the natural uranium irradiated by 18O ions was developed. The γ spectrum of the thorium fraction shows that the most of the reaction products, especially U, Ce and I can be completely removed by using the procedure.

  5. The Nopal 1 Uranium Deposit: an Overview

    Science.gov (United States)

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

    2007-05-01

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

  6. Spectroscopic studies of uranium species for environmental decontamination applications

    Science.gov (United States)

    Eng, Charlotte

    After the Cold War, Department of Energy began to concentrate its efforts on cleanup of former nuclear material processing facilities, especially uranium-contaminated groundwater and soil. This research aims to study uranium association to both organic and inorganic compounds found in the contaminated environment in the hopes that the information gathered can be applied to the development and optimization of cost-effective remediation techniques. Spectroscopic and electrochemical methods will be employed to examine the behavior of uranium in given conditions to further our understanding of its impact on the environment. Uranium found in groundwater and soil bind with various ligands, especially organic ligands present in the environment due to natural sources (e.g. metabolic by-products or degradation of plants and animals) or man-made sources (e.g. chelating agents used in operating or cleanup of uranium processing facilities). We selected reasonable analogs of naturally occurring matter and studied their structure, chemical and electrochemical behavior and found that the structure of uranyl complexes depends heavily on the nature of the ligand and environmental factors such as pH. Association of uranium-organic complexes with anaerobic bacteria, Clostridium sp. was studied to establish if the bacteria can effectively bioreduce uranium while going through normal bacterial activity. It was found that the nature of the organic ligand affected the bioavailability and toxicity of the uranium on the bacteria. In addition, we have found that the type of iron corrosion products and uranyl species present on the surface of corroded steel depended on various environmental factors, which subsequently affected the removal rate of uranium by a citric acid/hydrogen peroxide/deionized water cleaning process. The method was found to remove uranium from only the topmost corrosion layers and residual uranium could be found (a) deeper in the corrosion layers where it is occluded by

  7. Improved fluorimetric measurement of uranium uptake and distribution in spring wheat (Triticum aestivum L.)

    Energy Technology Data Exchange (ETDEWEB)

    Borcia, Catalin [' ' Alexandru Ioan Cuza' ' Univ., Iasi (Romania). Dept. of Physics; Popa, Karin; Cecal, Alexandru [' ' Alexandru Ioan Cuza' ' Univ., Iasi (Romania). Dept. of Chemistry; Murariu, Manuela [' ' Petru Poni' ' Institute of Macromolecular Chemistry, Iasi (Romania)

    2016-08-01

    Uranium uptake and (radio)toxicity was tested on spring wheat (Triticum aestivum L.) in a laboratory study using differently concentrated uranium nitrate solutions. Within these experiments, two analytical assays of uranium were comparatively tested: a fast and improved fluorimetric assay and the classical colorimetric (U(IV)-arsenazo(III) complexation) one. During the germination, the wheat seeds and plantlets supported well the uranium solutions of treatment within the entire concentration range (1 x 10{sup -4} -5 x 10{sup -3} M). Uranium proved to be non (radio)toxic to wheat as compared with other natural and anthropogenic radiocations, probably because its uptake by spring wheat during the germination is low. Indeed, only a small fraction of uranium administered was located within the roots, whereas the uranium content of the stems was negligible. A high correlation between the results obtained by two analytical methods was found. However, the fluorimetric assay proved to be more reliable and fast, and accurate.

  8. Spatial and temporal variation of uranium in a shallow weathered rock aquifer in southern India

    Indian Academy of Sciences (India)

    K Brindha; L Elango; R N Nair

    2011-10-01

    Uranium occurs naturally in groundwater and surface water. The objective of this study is to understand the causes for the occurrence of uranium and its spatio-temporal variation in groundwater in a part of Nalgonda district, Andhra Pradesh, south India. Uranium deposits occur in the southeastern part of this area. Groundwater samples were collected from 44 wells every two months from March 2008 to January 2009. The samples were analyzed for pH, ORP and uranium concentration. The uranium concentration in groundwater varies from 0.2 ppb to a maximum of 68 ppb with a mean of 18.5 ppb. About 21.6% of the samples were above the drinking water limit of 30 ppb set by USEPA. The uranium concentration varied with fluctuation in groundwater level, pH and ORP. Uranium concentration in groundwater changes depending on lithology, degree of weathering and rainfall recharge.

  9. Efficiency of sepiolite in broilers diet as uranium adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Mitrovic, Branislava M.; Lazarevic-Macanovic, Mirjana; Krstic, Nikola [University of Belgrade, Department of Radiology and Radiation Hygiene, Faculty of Veterinary Medicine, Belgrade (Serbia); Jovanovic, Milijan [University of Belgrade, Department of Veterinary Pathology, Faculty of Veterinary Medicine, Belgrade (Serbia); Janackovic, Djordje [University of Belgrade, Faculty of Technology and Metallurgy, Belgrade (Serbia); Stojanovic, Mirjana [University of Belgrade, Institute for Technology of Nuclear and Other Mineral Row Materials, Belgrade (Serbia); Mirilovic, Milorad [University of Belgrade, Department of Economics and Statistics, Faculty of Veterinary Medicine, Belgrade (Serbia)

    2015-05-15

    The use of phosphate mineral products in animal nutrition, as a major source of phosphor and calcium, can lead to uranium entering the food chain. The aim of the present study was to determine the protective effect of natural sepiolite and sepiolite treated with acid for broilers after oral intake of uranium. The broilers were contaminated for 7 days with 25 mg/uranyl nitrate per day. Two different adsorbents (natural sepiolite and sepiolite treated with acid) were given via gastric tube immediately after the oral administration of uranium. Natural sepiolite reduced uranium distribution by 57 % in kidney, 80 % in liver, 42 % in brain, and 56 % in muscle. A lower protective effect was observed after the administration of sepiolite treated with acid, resulting in significant damage of intestinal villi in the form of shortening, fragmentation, and necrosis, and histopathological lesions on kidney in the form of edema and abruption of epithelial cells in tubules. When broilers received only sepiolite treated with acid (no uranyl nitrate), shortening of intestinal villi occurred. Kidney injuries were evident when uranium concentrations in kidney were 0.88 and 1.25 μg/g dry weight. It is concluded that adding of natural sepiolite to the diets of broilers can reduce uranium distribution in organs by significant amount without adverse side effects. (orig.)

  10. Innovative Elution Processes for Recovering Uranium from Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wai, Chien [Univ. of Idaho, Moscow, ID (United States); Tian, Guoxin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Janke, Christopher [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-05-29

    Utilizing amidoxime-based polymer sorbents for extraction of uranium from seawater has attracted considerable interest in recent years. Uranium collected in the sorbent is recovered typically by elution with an acid. One drawback of acid elution is deterioration of the sorbent which is a significant factor that limits the economic competitiveness of the amidoxime-based sorbent systems for sequestering uranium from seawater. Developing innovative elution processes to improve efficiency and to minimize loss of sorbent capacity become essential in order to make this technology economically feasible for large-scale industrial applications. This project has evaluated several elution processes including acid elution, carbonate elution, and supercritical fluid elution for recovering uranium from amidoxime-based polymer sorbents. The elution efficiency, durability and sorbent regeneration for repeated uranium adsorption- desorption cycles in simulated seawater have been studied. Spectroscopic techniques are used to evaluate chemical nature of the sorbent before and after elution. A sodium carbonate-hydrogen peroxide elution process for effective removal of uranium from amidoxime-based sorbent is developed. The cause of this sodium carbonate and hydrogen peroxide synergistic leaching of uranium from amidoxime-based sorbent is attributed to the formation of an extremely stable uranyl peroxo-carbonato complex. The efficiency of uranium elution by the carbonate-hydrogen peroxide method is comparable to that of the hydrochloric acid elution but damage to the sorbent material is much less for the former. The carbonate- hydrogen peroxide elution also does not need any elaborate step to regenerate the sorbent as those required for hydrochloric acid leaching. Several CO2-soluble ligands have been tested for extraction of uranium from the sorbent in supercritical fluid carbon dioxide. A mixture of hexafluoroacetylacetone and tri-n-butylphosphate shows the best result but uranium

  11. Design Parameters for a Natural Uranium UO{sub 3} or U{sub 3}O{sub 8} Fueled Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, C.M.

    2002-11-15

    A recent Oak Ridge National Laboratory report provided preliminary analyses to propose alternative design parameters for a nuclear reactor that could be fueled with natural UO{sub 3} or U{sub 3}O{sub 8} and moderated with either heavy water or reactor-grade graphite. This report provides more specific reactor design and operating parameters for a heavy water-moderated reactor only. The basic assumptions and analytical approach are discussed together with the results of the analysis.

  12. Toxicity of Uranium Adsorbent Materials using the Microtox Toxicity Test

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jiyeon [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jeters, Robert T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bonheyo, George T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-01

    The Marine Sciences Laboratory at the Pacific Northwest National Laboratory evaluated the toxicity of a diverse range of natural and synthetic materials used to extract uranium from seawater. The uranium adsorbent materials are being developed as part of the U. S. Department of Energy, Office of Nuclear Energy, Fuel Resources Program. The goal of this effort was to identify whether deployment of a farm of these materials into the marine environment would have any toxic effects on marine organisms.

  13. Distribution of uranium, thorium and some stable trace and toxic elements in human hair and nails in Niška Banja Town, a high natural background radiation area of Serbia (Balkan Region, South-East Europe).

    Science.gov (United States)

    Sahoo, S K; Žunić, Z S; Kritsananuwat, R; Zagrodzki, P; Bossew, P; Veselinovic, N; Mishra, S; Yonehara, H; Tokonami, S

    2015-07-01

    Human hair and nails can be considered as bio-indicators of the public exposure to certain natural radionuclides and other toxic metals over a long period of months or even years. The level of elements in hair and nails usually reflect their levels in other tissues of body. Niška Banja, a spa town located in southern Serbia, with locally high natural background radiation was selected for the study. To assess public exposure to the trace elements, hair and nail samples were collected and analyzed. The concentrations of uranium, thorium and some trace and toxic elements (Mn, Ni, Cu, Sr, Cd, and Cs) were determined using inductively coupled plasma mass spectrometry (ICP-MS). U and Th concentrations in hair varied from 0.0002 to 0.0771 μg/g and from 0.0002 to 0.0276 μg/g, respectively. The concentrations in nails varied from 0.0025 to 0.0447 μg/g and from 0.0023 to 0.0564 μg/g for U and Th, respectively. We found significant correlations between some elements in hair and nails. Also indications of spatial clustering of high values could be found. However, this phenomenon as well as the large variations in concentrations of heavy metals in hair and nail could not be explained. As hypotheses, we propose possible exposure pathways which may explain the findings, but the current data does not allow testing them. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  14. Understanding uranium behaviour at the Askola uranium mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Jokelainen, L.; Siitari-Kauppi, M. [Univ. of Helsinki, Helsinki Univ. (Finland); Markovaara-Koivisto, M. [Helsinki Univ. of Technology, TKK (Finland); Read, D. [Enterpris, The Old Library, Lower Shott, Great Bookham, Surrey (United Kingdom); Lindberg, A. [Geological Survey of Finland, Espoo (Finland); Hellmuth, K.H. [Radiation and Nuclear Safety Authority, Helsinki (Finland)

    2010-07-01

    Understanding the behaviour of uranium is essential when assessing the safety of a spent nuclear fuel repository. The geochemical behaviour of uranium, including its reactive transport chemistry, is also a matter of concern when assessing the environmental impact of uranium mining. Subsurface uranium mobility is believed to be primarily controlled by dissolution and (co)-precipitation of uranium mineral solids and adsorption to mineral surfaces. This paper describes a modelling exercise based on characterisation of samples taken from drilled cores at the uranium mineralization at Askola, Southern Finland. In the modelling exercise, current conditions are assumed to be oxidizing and saturated with groundwater. PHREEQC was used for modelling in conjunction with the Lawrence Livermore National Laboratory database, chosen for its extensive coverage of uranium species and mineral phases. It is postulated that weathering processes near the surface have led to uranium dissolution from the primary ore, leaching out from the matrix and migrating along water-conducting fractures with subsequent re-diffusion into the rock matrix. Electron microscopy studies show that precipitated uranium occupies intra-granular fractures in feldspars and quartz. In addition, secondary uranium was found to be distributed within goethite nodules as well as around the margins of iron-containing minerals in the form of silicate and phosphate precipitates. Equilibrium modelling calculations predict that uranium would be precipitated as uranyl silicates, most likely soddyite and uranophane, in the prevailing chemical conditions beneath Lakeakallio hill. (orig.)

  15. Ecological and corrosion behavior of depleted uranium

    Directory of Open Access Journals (Sweden)

    Stojanović Mirjana D.

    2015-01-01

    Full Text Available Environmental pollution with radionuclides, particularly uranium and its decay products is a serious global problem. The current scientific studies estimated that the contamination originating from TENORM, caused by nuclear and non-nuclear technologies, has significantly increased natural level of radioactivity in the last thirty years. During the last decades all the more were talking about the "new pollutant" - depleted uranium (DU, which has been used in anti-tank penetrators because of its high density, penetration and pyrophoric properties. It is estimated that during the Gulf War, the war in Bosnia and Yugoslavia and during the invasion of Iraq, 1.4 million missiles with depleted uranium was fired. During the NATO aggression against the ex Yugoslavia in 1999., 112 locations in Kosovo and Metohija, 12 locations in southern Serbia and two locations in Montenegro were bombed. On this occasion, approximately 10 tons of depleted uranium were entered into the environment, mainly on land, where the degree of contamination ranged from 200 Bq / kg to 235 000 Bq/kg, which is up to 1000 times higher than the natural level. Fourteen years ago there was very little information about the behavior of ecological systems damaged by DU penetrators fired. Today, unfortunately, we are increasingly faced with the ―invisible threat" of depleted uranium, which has a strong radioactive and hemotoxic impact on human health. Present paper provides a detailed overview of the current understanding of corrosion and corrosion behavior of DU and environmental factors that control corrosion, together with indicators of environmental impact in order to highlight areas that need further attention in developing remediation programs.

  16. Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Horng-Bin [Department of Chemistry, University of Idaho, Moscow, Idaho 83844 USA; Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow, Idaho 83844 USA; Kuo, Li-Jung [Pacific Northwest National Laboratory, Marine Sciences Laboratory, Sequim, Washington 98382 USA; Gill, Gary [Pacific Northwest National Laboratory, Marine Sciences Laboratory, Sequim, Washington 98382 USA; Tian, Guoxin [Lawrence Berkeley National Laboratory, Berkeley, California 94720 USA; Rao, Linfeng [Lawrence Berkeley National Laboratory, Berkeley, California 94720 USA; Das, Sadananda [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA; Mayes, Richard T. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA; Janke, Christopher J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA

    2017-05-02

    Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10-3 M) in seawater. In real seawater experiments, the bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent. Using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.

  17. Extracting Uranium from Seawater: Promising AI Series Adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.; Oyola, Y.; Mayes, R. T.; Janke, C. J.; Kuo, L. -J.; Gill, G.; Wood, J. R.; Dai, S.

    2016-04-20

    A new series of adsorbents (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole to mole ratios) onto high surface area polyethylene fiber, with high degrees of grafting (DOG) varying from 110 to 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 5 wt % hydroxylamine at 80 °C for 72 h. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with prescreening brine spiked with 8 ppm uranium. Uranium adsorption capacities in prescreening ranged from 171 to 187 g-U/kg-ads irrespective of percent DOG. The performance of the adsorbents with respect to uranium adsorption in natural seawater was also investigated using flow-throughcolumn testing at the Pacific Northwest National Laboratory (PNNL). Three hours of KOH conditioning led to higher uranium uptake than 1 h of conditioning. The adsorbent AI11, containing AN and VPA at the mole ratio of 3.52, emerged as the potential candidate for the highest uranium adsorption (3.35 g-U/kg-ads.) after 56 days of exposure in seawater flow-through-columns. The rate of vanadium adsorption over uranium linearly increased throughout the 56 days of exposure. The total mass of vanadium uptake was ~5 times greater than uranium after 56 days.

  18. Chattanooga shale: uranium recovery by in situ processing

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, D.D.

    1977-04-25

    The increasing demand for uranium as reactor fuel requires the addition of sizable new domestic reserves. One of the largest potential sources of low-grade uranium ore is the Chattanooga shale--a formation in Tennessee and neighboring states that has not been mined conventionally because it is expensive and environmentally disadvantageous to do so. An in situ process, on the other hand, might be used to extract uranium from this formation without the attendant problems of conventional mining. We have suggested developing such a process, in which fracturing, retorting, and pressure leaching might be used to extract the uranium. The potential advantages of such a process are that capital investment would be reduced, handling and disposing of the ore would be avoided, and leaching reagents would be self-generated from air and water. If successful, the cost reductions from these factors could make the uranium produced competitive with that from other sources, and substantially increase domestic reserves. A technical program to evaluate the processing problems has been outlined and a conceptual model of the extraction process has been developed. Preliminary cost estimates have been made, although it is recognized that their validity depends on how successfully the various processing steps are carried out. In view of the preliminary nature of this survey (and our growing need for uranium), we have urged a more detailed study on the feasibility of in situ methods for extracting uranium from the Chattanooga shale.

  19. Characterization and remediation of soils contaminated with uranium.

    Science.gov (United States)

    Gavrilescu, Maria; Pavel, Lucian Vasile; Cretescu, Igor

    2009-04-30

    Environmental contamination caused by radionuclides, in particular by uranium and its decay products is a serious problem worldwide. The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment. The objective of this paper is to develop a better understanding of the techniques for the remediation of soils polluted with radionuclides (uranium in particular), considering: the chemical forms of uranium, including depleted uranium (DU) in soil and other environmental media, their characteristics and concentrations, and some of the effects on environmental and human health; research issues concerning the remediation process, the benefits and results; a better understanding of the range of uses and situations for which each is most appropriate. The paper addresses the main features of the following techniques for uranium remediation: natural attenuation, physical methods, chemical processes (chemical extraction methods from contaminated soils assisted by various suitable chelators (sodium bicarbonate, citric acid, two-stage acid leaching procedure), extraction using supercritical fluids such as solvents, permeable reactive barriers), biological processes (biomineralization and microbial reduction, phytoremediation, biosorption), and electrokinetic methods. In addition, factors affecting uranium removal from soils are furthermore reviewed including soil characteristics, pH and reagent concentration, retention time.

  20. Uranium-Loaded Water Treatment Resins: 'Equivalent Feed' at NRC and Agreement State-Licensed Uranium Recovery Facilities - 12094

    Energy Technology Data Exchange (ETDEWEB)

    Camper, Larry W.; Michalak, Paul; Cohen, Stephen; Carter, Ted [Nuclear Regulatory Commission (United States)

    2012-07-01

    Community Water Systems (CWSs) are required to remove uranium from drinking water to meet EPA standards. Similarly, mining operations are required to remove uranium from their dewatering discharges to meet permitted surface water discharge limits. Ion exchange (IX) is the primary treatment strategy used by these operations, which loads uranium onto resin beads. Presently, uranium-loaded resin from CWSs and mining operations can be disposed as a waste product or processed by NRC- or Agreement State-licensed uranium recovery facilities if that licensed facility has applied for and received permission to process 'alternate feed'. The disposal of uranium-loaded resin is costly and the cost to amend a uranium recovery license to accept alternate feed can be a strong disincentive to commercial uranium recovery facilities. In response to this issue, the NRC issued a Regulatory Issue Summary (RIS) to clarify the agency's policy that uranium-loaded resin from CWSs and mining operations can be processed by NRC- or Agreement State-licensed uranium recovery facilities without the need for an alternate feed license amendment when these resins are essentially the same, chemically and physically, to resins that licensed uranium recovery facilities currently use (i.e., equivalent feed). NRC staff is clarifying its current alternate feed policy to declare IX resins as equivalent feed. This clarification is necessary to alleviate a regulatory and financial burden on facilities that filter uranium using IX resin, such as CWSs and mine dewatering operations. Disposing of those resins in a licensed facility could be 40 to 50 percent of the total operations and maintenance (O and M) cost for a CWS. Allowing uranium recovery facilities to treat these resins without requiring a license amendment lowers O and M costs and captures a valuable natural resource. (authors)

  1. Uranium from Seawater Program Review; Fuel Resources Uranium from Seawater Program DOE Office of Nuclear Energy

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-01

    For nuclear energy to remain sustainable in the United States, economically viable sources of uranium beyond terrestrial ores must be developed. The goal of this program is to develop advanced adsorbents that can extract uranium from seawater at twice the capacity of the best adsorbent developed by researchers at the Japan Atomic Energy Agency (JAEA), 1.5 mg U/g adsorbent. A multidisciplinary team from Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, Pacific Northwest National Laboratory, and the University of Texas at Austin was assembled to address this challenging problem. Polymeric adsorbents, based on the radiation grafting of acrylonitrile and methacrylic acid onto high surface-area polyethylene fibers followed by conversion of the nitriles to amidoximes, have been developed. These poly(acrylamidoxime-co-methacrylic acid) fibers showed uranium adsorption capacities for the extraction of uranium from seawater that exceed 3 mg U/g adsorbent in testing at the Pacific Northwest National Laboratory Marine Sciences Laboratory. The essence of this novel technology lies in the unique high surface-area trunk material that considerably increases the grafting yield of functional groups without compromising its mechanical properties. This technology received an R&D100 Award in 2012. In addition, high surface area nanomaterial adsorbents are under development with the goal of increasing uranium adsorption capacity by taking advantage of the high surface areas and tunable porosity of carbon-based nanomaterials. Simultaneously, de novo structure-based computational design methods are being used to design more selective and stable ligands and the most promising candidates are being synthesized, tested and evaluated for incorporation onto a support matrix. Fundamental thermodynamic and kinetic studies are being carried out to improve the adsorption efficiency, the selectivity of uranium over other metals, and the stability of the adsorbents. Understanding

  2. Conversion disorder

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000954.htm Conversion disorder To use the sharing features on this page, please enable JavaScript. Conversion disorder is a mental condition in which a person ...

  3. Comparative studies on the interactions of the natural isolate KS5 and one reference strain (DSM 10134) with uranium(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Ulrike; Krawczyk-Baersch, Evelyn [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Biogeochemistry; Arnold, Thuro [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2016-07-01

    The yeast KS5 (Rhodosporidium toruloides) was isolated by culture dependent method directly from the flooding water in Koenigstein (Germany). To compare the U tolerance and immobilization ability of the isolate a reference culture DSM 10134 (R. toruloides) was applied. Both cultures displayed the ability to tolerate high amounts of U, in contrast the reference KS5 showed a six-fold higher U tolerance in comparison to the reference strain. U immobilization studies displayed that both organisms are able to remove high amounts. The flooding water in Koenigstein has to be cleaned up for many years by an intensive waste water treatment plant. Possibly, with the help of natural occuring microorganisms the flooding water could be cleaned up using in situ bioremediation.

  4. Uranium-series radionuclides as tracers of geochemical processes in Long Island Sound. [Natural /sup 210/Pb tracer study of estuarine geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Benninger, L.K.

    1976-05-01

    An estuary can be visualized as a membrane between land and the deep ocean, and the understanding of the estuarine processes which determine the permeability of this membrane to terrigenous materials is necessary for the estimation of fluxes of these materials to the oceans. Natural radionuclides are useful probes into estuarine geochemistry because of the time-dependent relationships among them and because, as analogs of stable elements, they are much less subject to contamination during sampling and analysis. In this study the flux of heavy metals through Long Island Sound is considered in light of the material balance for excess /sup 210/Pb, and analyses of concurrent seston and water samples from central Long Island Sound are used to probe the internal workings of the estuary.

  5. Uranium from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Gregg, D.; Folkendt, M.

    1982-09-21

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

  6. Distribution and potential health risk of groundwater uranium in Korea.

    Science.gov (United States)

    Shin, Woosik; Oh, Jungsun; Choung, Sungwook; Cho, Byong-Wook; Lee, Kwang-Sik; Yun, Uk; Woo, Nam-Chil; Kim, Hyun Koo

    2016-11-01

    Chronic exposure even to extremely low specific radioactivity of natural uranium in groundwater results in kidney problems and potential toxicity in bones. This study was conducted to assess the potential health risk via intake of the groundwater containing uranium, based on the determination of the uranium occurrence in groundwater. The groundwater was investigated from a total of 4140 wells in Korea. Most of the groundwater samples showed neutral pH and (sub-)oxic condition that was influenced by the mixing with shallow groundwater due to long-screened (open) wells. High uranium contents exceeding the WHO guideline level of 30 μg L(-1) were observed in the 160 wells located mainly in the plutonic bedrock regions. The statistical analysis suggested that the uranium component was present in groundwater by desorption and re-dissolution processes. Predominant uranium phases were estimated to uranyl carbonates under the Korean groundwater circumstances. These mobile forms of uranium and oxic condition facilitate the increase of potential health risk downgradient. In particular, long-term intake of groundwater containing >200 μg U L(-1) may induce internal exposure to radiation as well as the effects of chemical toxicity. These high uranium concentrations were found in twenty four sampling wells of rural areas in this study, and they were mainly used for drinking. Therefore, the high-level uranium wells and neighboring areas must be properly managed and monitored to reduce the exposure risk for the residents by drinking groundwater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Uranium Potential and Regional Metallogeny in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jindai; LI Ziying

    2008-01-01

    This paper is briefly involved in distributions of China's uranium metallogenic types,provinces, regions and belts. Eight target regions have been pointed out to be worthy of prospectingfor uranium resources. The regional uranium metallogeny is discussed and great uranium potentialpointed out from many aspects. Generally speaking, there are favorable conditions for uraniummineralization and good perspective to explore for uranium resources.

  8. Method of preparation of uranium nitride

    Science.gov (United States)

    Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

    2013-07-09

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

  9. Importance of Organic Matter-Uranium Biogeochemistry to Uranium Plume Persistence in the Upper Colorado River Basin

    Science.gov (United States)

    Bargar, J.; Janot, N.; Jones, M. E.; Bone, S. E.; Lezama-Pacheco, J.; Fendorf, S. E.; Long, P. E.; Williams, K. H.; Bush, R. P.

    2014-12-01

    Recent evidence suggests that biologically driven redox reactions, fueled by sedimentary lenses enriched in detrital organic matter, play major roles in maintaining the persistent uranium groundwater plume in the subsurface at the U.S. Department of Enery's Rifle, CO field research site. Biogeochemical cycling of C, N, Fe, and S is highly active in these organic-rich naturally reduced zones (NRZs), and uranium is present as U(IV). The speciation of these elements profoundly influences the susceptibility of uranium to be reoxidized and remobiliized and contribute to plume persistence. However, uranim speciation in particular is poorly constrained in these sytems. To better evaluate the importance of NRZs to uranium mobility and plume persistence at the Rifle site, the DOE-BER-funded SLAC SFA team has characterized vertical concentration profiles and speciation of uranium, iron, sulfur, and NOM in well bores at high spatial resolution (4 inch intervals). Up to 95% of the sedimentary uranium pool was found to be concentrated in NRZs, where it occurs dominantly as non-crystalline forms of U(IV). Uranium accumulation and the presence of the short-lived sulfide mackinawite (FeS) at NRZ-aquifer interfaces indicate that NRZs actively exchange solutes with the surrounding aquifer. Moreover, sediment textures indicate that NRZs are likely to be abundant in riparian zones throughout the upper Colorado River basin (U.S.A.), which contains most of the contaminated DOE legacy uranium ore processing sites in the U.S. These results suggest that NRZ-uranium interactions may be important to plume persistence regionally and emphasize the importance of understanding molecular-scale processes.

  10. A density functional theory study of uranium-doped thoria and uranium adatoms on the major surfaces of thorium dioxide

    Science.gov (United States)

    Shields, Ashley E.; Santos-Carballal, David; de Leeuw, Nora H.

    2016-05-01

    Thorium dioxide is of significant research interest for its use as a nuclear fuel, particularly as part of mixed oxide fuels. We present the results of a density functional theory (DFT) study of uranium-substituted thorium dioxide, where we found that increasing levels of uranium substitution increases the covalent nature of the bonding in the bulk ThO2 crystal. Three low Miller index surfaces have been simulated and we propose the Wulff morphology for a ThO2 particle and STM images for the (100), (110), and (111) surfaces studied in this work. We have also calculated the adsorption of a uranium atom and the U adatom is found to absorb strongly on all three surfaces, with particular preference for the less stable (100) and (110) surfaces, thus providing a route to the incorporation of uranium into a growing thoria particle.

  11. Up-Conversion Intersystem Crossing Rates in Organic Emitters for Thermally Activated Delayed Fluorescence: Impact of the Nature of Singlet vs Triplet Excited States

    KAUST Repository

    Samanta, Pralok Kumar

    2017-02-28

    The rates for up-conversion intersystem crossing (UISC) from the T1 state to the S1 state are calculated for a series of organic emitters with an emphasis on thermally activated delayed fluorescence (TADF) materials. Both the spin-orbit coupling and the energy difference between the S1 and T1 states (ΔEST) are evaluated, at the density functional theory (DFT) and time-dependent DFT levels. The calculated UISC rates and ΔEST values are found to be in good agreement with available experimental data. Our results underline that small ΔEST values and sizable spin-orbit coupling matrix elements have to be simultaneously realized in order to facilitate UISC and ultimately TADF. Importantly, the spatial separation of the highest occupied and lowest unoccupied molecular orbitals of the emitter, a widely accepted strategy for the design of TADF molecules, does not necessarily lead to a sufficient reduction in ΔEST; in fact, either a significant charge-transfer (CT) contribution to the T1 state or a minimal energy difference between the local-excitation and charge-transfer triplet states is required to achieve a small ΔEST. Also, having S1 and T1 states of a different nature is found to strongly enhance spin-orbit coupling, which is consistent with the El-Sayed rule for ISC rates. Overall, our results indicate that having either similar energies for the local-excitation and charge-transfer triplet states or the right balance between a substantial CT contribution to T1 and somewhat different natures of the S1 and T1 states, paves the way toward UISC enhancement and thus TADF efficiency improvement.

  12. Direct conversion of natural gas into COx-free hydrogen and MWCNTs over commercial Ni–Mo/Al2O3 catalyst: Effect of reaction parameters

    Directory of Open Access Journals (Sweden)

    Ahmed E. Awadallah

    2013-06-01

    Full Text Available A commercial hydrotreating nickel molybdate/alumina catalyst was used for the direct conversion of natural gas (NG into COx-free hydrogen and a co-valuable product of multi-walled carbon nanotubes (MWCNTs. The catalytic runs were carried out atmospherically in a fixed-bed flow reactor. The effect of reaction temperature between 600 and 800 °C, and dilution of the NG feed with nitrogen as well as pretreatment of the catalyst with hydrogen were investigated. At a reaction temperature of 700 °C and dilution ratio of NG/N2 = 20/30, the optimum yield of H2 (∼80% was obtained with higher longevity. However, using the feed ratio of NG/N2 = 30/20, the optimum yield of MWCNTs was obtained (669%. X-ray diffraction pattern for the catalyst after the reaction showed that the MWCNTs were grown on the catalyst at all reaction temperatures under study. TEM pictures revealed that the as-grown MWCNTs at 600, 650 and 800 °C are short and long with a low graphitization degree. At 700 °C a forest of condensed CNTs is formed, whereas both carbon nanofibers and CNTs were formed at 750 °C.

  13. Behavior of uranium under conditions of interaction of rocks and ores with subsurface water

    Science.gov (United States)

    Omel'Yanenko, B. I.; Petrov, V. A.; Poluektov, V. V.

    2007-10-01

    The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ≤10-8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO2) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water

  14. Predictability of conversation partners

    CERN Document Server

    Takaguchi, Taro; Sato, Nobuo; Yano, Kazuo; Masuda, Naoki

    2011-01-01

    Recent developments in sensing technologies have enabled us to examine the nature of human social behavior in greater detail. By applying an information theoretic method to the spatiotemporal data of cell-phone locations, Song et al. (2010) found that human mobility patterns are remarkably predictable. Inspired by their work, we address a similar predictability question in a different kind of human social activity: conversation events. The predictability in the sequence of one's conversation partners is defined as the degree to which one's next conversation partner can be predicted given the current partner. We quantify this predictability by using the mutual information. We examine the predictability of conversation events for each individual using the longitudinal data of face-to-face interactions collected from two company offices in Japan. Each subject wears a name tag equipped with an infrared sensor node, and conversation events are marked when signals are exchanged between close sensor nodes. We find t...

  15. ELECTROLYSIS OF THORIUM AND URANIUM

    Science.gov (United States)

    Hansen, W.N.

    1960-09-01

    An electrolytic method is given for obtaining pure thorium, uranium, and thorium-uranium alloys. The electrolytic cell comprises a cathode composed of a metal selected from the class consisting of zinc, cadmium, tin, lead, antimony, and bismuth, an anode composed of at least one of the metals selected from the group consisting of thorium and uranium in an impure state, and an electrolyte composed of a fused salt containing at least one of the salts of the metals selected from the class consisting of thorium, uranium. zinc, cadmium, tin, lead, antimony, and bismuth. Electrolysis of the fused salt while the cathode is maintained in the molten condition deposits thorium, uranium, or thorium-uranium alloys in pure form in the molten cathode which thereafter may be separated from the molten cathode product by distillation.

  16. Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

    Science.gov (United States)

    Popov, L

    2016-09-01

    Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials.

  17. Uranium Critical Point Location Problem

    CERN Document Server

    Iosilevskiy, Igor

    2013-01-01

    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.

  18. Radiochemistry of uranium

    Energy Technology Data Exchange (ETDEWEB)

    Gindler, J.E.

    1962-03-01

    This volume which deals with the radiochemistry of uranium is one of a series of monographs on radiochemistry of the elements. There is included a review of the nuclear and chemical features of particular interest to the radiochemist, a discussion of problems of dissolution of a sample and counting technique, and finally, a collection of radiochemical procedures for the element as found in the literature.

  19. METHOD FOR RECOVERING URANIUM FROM OILS

    Science.gov (United States)

    Gooch, L.H.

    1959-07-14

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

  20. URANIUM MARKET TRENDS

    Directory of Open Access Journals (Sweden)

    Serghei MĂRGULESCU

    2016-06-01

    Full Text Available The recent UN Climate Talks in Paris have put forward the goal of limiting the global temperature rise to two degrees Celsius by the end of the century. This is providing a strong political base for expanding the nuclear power capacity because of the critical role that nuclear power plants play in the production of electricity without emissions of greenhouse gases. In all, more than a dozen countries get over 25% of their energy from nuclear power, with 437 nuclear reactors operating around the world. On top of that, there are another 71 reactors under construction, 165 planned, and 315 proposed. Global uranium demand is expected to rise 40% by 2025 and 81% by 2035. Mined supply of uranium will struggle to keep pace amid rising demand and falling secondary supplies. A cumulative supply deficit is expected to emerge by 2021 while 2016 marks a huge inflection point for the industry, beeing the first year that demand will actually exceed supplies, creating a 60,000-tonne shortfall by 2018. Over the next 10 years, we're going to see uranium prices more than double while the bull run will begin in earnest in 2016.

  1. Design Study for a Low-Enriched Uranium Core for the High Flux Isotope Reactor, Annual report for FY 2009

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, David [ORNL; Freels, James D [ORNL; Ilas, Germina [ORNL; Miller, James Henry [ORNL; Primm, Trent [ORNL; Sease, John D [ORNL; Guida, Tracey [University of Pittsburgh; Jolly, Brian C [ORNL

    2010-02-01

    This report documents progress made during FY 2009 in studies of converting the High Flux Isotope Reactor (HFIR) from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. With axial and radial grading of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in reactor performance from the current level. Results of selected benchmark studies imply that calculations of LEU performance are accurate. Studies are reported of the application of a silicon coating to surrogates for spheres of uranium-molybdenum alloy. A discussion of difficulties with preparing a fuel specification for the uranium-molybdenum alloy is provided. A description of the progress in developing a finite element thermal hydraulics model of the LEU core is provided.

  2. SEPARATION OF THORIUM FROM URANIUM

    Science.gov (United States)

    Bane, R.W.

    1959-09-01

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

  3. Webinar on the Removal of Uranium from Drinking Water by Small System Treatment Technology

    Science.gov (United States)

    Abstract: Radionuclides, such as uranium (U), occur naturally as trace elements in rocks and soils and thus can be found in dissolved forms in ground waters. Uranium has four oxidation states (+3, +4, +5, and +6) and is a very reactive element forming a variety of stable complexe...

  4. Conceptual Core Analysis of Long Life PWR Utilizing Thorium-Uranium Fuel Cycle

    Science.gov (United States)

    Rouf; Su'ud, Zaki

    2016-08-01

    Conceptual core analysis of long life PWR utilizing thorium-uranium based fuel has conducted. The purpose of this study is to evaluate neutronic behavior of reactor core using combined thorium and enriched uranium fuel. Based on this fuel composition, reactor core have higher conversion ratio rather than conventional fuel which could give longer operation length. This simulation performed using SRAC Code System based on library SRACLIB-JDL32. The calculation carried out for (Th-U)O2 and (Th-U)C fuel with uranium composition 30 - 40% and gadolinium (Gd2O3) as burnable poison 0,0125%. The fuel composition adjusted to obtain burn up length 10 - 15 years under thermal power 600 - 1000 MWt. The key properties such as uranium enrichment, fuel volume fraction, percentage of uranium are evaluated. Core calculation on this study adopted R-Z geometry divided by 3 region, each region have different uranium enrichment. The result show multiplication factor every burn up step for 15 years operation length, power distribution behavior, power peaking factor, and conversion ratio. The optimum core design achieved when thermal power 600 MWt, percentage of uranium 35%, U-235 enrichment 11 - 13%, with 14 years operation length, axial and radial power peaking factor about 1.5 and 1.2 respectively.

  5. Measurements of radon around closed uranium mines

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Sadaaki E-mail: furuta@ningyo.jnc.go.jp; Ito, Kimio; Ishimori, Yuu

    2002-07-01

    There are several waste rock yards at closed uranium mines around Ningyo-toge, in the Western Honshu Island of Japan, and measurements of radon were carried out by both the passive method and the sampling method around these yards. As comparatively high radon concentrations were observed in two districts through routine measurements, more detailed measurements were made by the passive method in these districts. The impact of radon emanation from the waste rock yards was small for both residential districts and around these yards when considering the natural background level of radon. In addition, by simultaneous continuous measurements of radon and its progeny at two locations, it was estimated that the effective dose caused by the representative uranium waste rock yards was less than the public effective dose limit of 1 mSv year{sup -1} at the fenced boundary of the waste rock site.

  6. Determination of irradiated reactor uranium in soil samples in Belarus using 236U as irradiated uranium tracer.

    Science.gov (United States)

    Mironov, Vladislav P; Matusevich, Janna L; Kudrjashov, Vladimir P; Boulyga, Sergei F; Becker, J Sabine

    2002-12-01

    This work presents experimental results on the distribution of irradiated reactor uranium from fallout after the accident at Chernobyl Nuclear Power Plant (NPP) in comparison to natural uranium distribution in different soil types. Oxidation processes and vertical migration of irradiated uranium in soils typical of the 30 km relocation area around Chernobyl NPP were studied using 236U as the tracer for irradiated reactor uranium and inductively coupled plasma mass spectrometry as the analytical method for uranium isotope ratio measurements. Measurements of natural uranium yielded significant variations of its concentration in upper soil layers from 2 x 10(-7) g g(-1) to 3.4 x 10(-6) g g(-1). Concentrations of irradiated uranium in the upper 0-10 cm soil layers at the investigated sampling sites varied from 5 x 10(-12) g g(-1) to 2 x 10(-6) g g(-1) depending on the distance from Chernobyl NPP. In the majority of investigated soil profiles 78% to 97% of irradiated "Chernobyl" uranium is still contained in the upper 0-10 cm soil layers. The physical and chemical characteristics of the soil do not have any significant influence on processes of fuel particle destruction. Results obtained using carbonate leaching of 236U confirmed that more than 60% of irradiated "Chernobyl" uranium is still in a tetravalent form, ie. it is included in the fuel matrix (non-oxidized fuel UO2). The average value of the destruction rate of fuel particles determined for the Western radioactive trace (k = 0.030 +/- 0.005 yr(-1)) and for the Northern radioactive trace (k = 0.035 + 0.009 yr(-1)) coincide within experimental errors. Use of leaching of fission products in comparison to leaching of uranium for study of the destruction rate of fuel particles yielded poor coincidence due to the fact that use of fission products does not take into account differences in the chemical properties of fission products and fuel matrix (uranium).

  7. Novel Sensor for the In Situ Measurement of Uranium Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Hatfield, Kirk [Univ. of Florida, Gainesville, FL (United States)

    2015-02-10

    controlled field conditions. In the third and fourth year a suite of larger field studies were conducted. For these studies, the uranium flux sensor was used with uranium speciation measurements and molecular-biological tools to characterize microbial community and active biomass at synonymous wells distributed in a large grid. These field efforts quantified spatial changes in uranium flux and field-scale rates of uranium attenuation (ambient and stimulated), uranium stability, and quantitatively assessed how fluxes and effective reaction rates were coupled to spatial variations in microbial community and active biomass. Analyses of data from these field experiments were used to generate estimates of Monod kinetic parameters that are ‘effective’ in nature and optimal for modeling uranium fate and transport at the field-scale. This project provided the opportunity to develop the first sensor that provides direct measures of both uranium (VI) and groundwater flux. A multidisciplinary team was assembled to include two geochemists, a microbiologist, and two quantitative contaminant hydrologists. Now that the project is complete, the sensor can be deployed at DOE sites to evaluate field-scale uranium attenuation, source behavior, the efficacy of remediation, and off-site risk. Because the sensor requires no power, it can be deployed at remote sites for periods of days to months. The fundamental science derived from this project can be used to advance the development of predictive models for various transport and attenuation processes in aquifers. Proper development of these models is critical for long-term stewardship of contaminated sites in the context of predicting uranium source behavior, remediation performance, and off-site risk.

  8. Chelation therapy for treatment of systemic intoxication with uranium: A review.

    Science.gov (United States)

    Šömen Joksić, Agnes; Katz, Sidney A

    2015-01-01

    Elevated levels of naturally occurring uranium have been found in small geographic areas throughout the world. Exposure of the general public to uranium is most often by the ingestion of food and water containing natural uranium from the hydrogeological environment, but this likelihood is remote. However, the risk is increased in regions where uranium is mined, milled, processed and/or fabricated as well as in the vicinity of former battlefields where depleted uranium munitions were deployed. Exposure in such cases is by the inhalation route. Internalized uranium is a long-term hazard the toxicity of which depends upon the dose and the dose rate as well as other parameters such as the chemical form and site of deposition of the uranium and the physiology of the host. The radiological toxicity and the chemical toxicity of uranium and its compounds are responsible for kidney damage and lung cancer. The vulnerable groups are the very young and the very old, individuals predisposed to hypertension or osteoporosis and individuals with chronic kidney disease. Those subject to long-term exposure from internalized uranium are a greater risk for the long-term implications. The accumulation of uranium may be mitigated by decreasing its absorption, distribution and deposition and increasing its elimination with chelating agents. The formation of soluble chelates may enhance the mobilization of uranium deposited in tissue and expedite its transport to and elimination from the renal system. The focus of this review is on the use of chelating agents to enhance decorporation of uranium thereby reducing the risk of intoxication.

  9. The distribution of depleted uranium contamination in Colonie, NY, USA

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, N.S., E-mail: nsl3@alumni.leicester.ac.uk [Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Chenery, S.R.N. [British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG (United Kingdom); Parrish, R.R. [Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG (United Kingdom)

    2009-12-20

    Uranium oxide particles were dispersed into the environment from a factory in Colonie (NY, USA) by prevailing winds during the 1960s and '70s. Uranium concentrations and isotope ratios from bulk soil samples have been accurately measured using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) without the need for analyte separation chemistry. The natural range of uranium concentrations in the Colonie soils has been estimated as 0.7-2.1 {mu}g g{sup -1}, with a weighted geometric mean of 1.05 {mu}g g{sup -1}; the contaminated soil samples comprise uranium up to 500 {+-} 40 {mu}g g{sup -1}. A plot of {sup 236}U/{sup 238}U against {sup 235}U/{sup 238}U isotope ratios describes a mixing line between natural uranium and depleted uranium (DU) in bulk soil samples; scatter from this line can be accounted for by heterogeneity in the DU particulate. The end-member of DU compositions aggregated in these bulk samples comprises (2.05 {+-} 0.06) x 10{sup -3235}U/{sup 238}U, (3.2 {+-} 0.1) x 10{sup -5236}U/{sup 238}U, and (7.1 {+-} 0.3) x 10{sup -6234}U/{sup 238}U. The analytical method is sensitive to as little as 50 ng g{sup -1} DU mixed with the natural uranium occurring in these soils. The contamination footprint has been mapped northward from site, and at least one third of the uranium in a soil sample from the surface 5 cm, collected 5.1 km NNW of the site, is DU. The distribution of contamination within the surface soil horizon follows a trend of exponential decrease with depth, which can be approximated by a simple diffusion model. Bioturbation by earthworms can account for dispersal of contaminant from the soil surface, in the form of primary uranium oxide particulates, and uranyl species that are adsorbed to organic matter. Considering this distribution, the total mass of uranium contamination emitted from the factory is estimated to be c. 4.8 tonnes.

  10. Solubilities of uranium for TILA-99

    Energy Technology Data Exchange (ETDEWEB)

    Ollila, K. [VTT Chemical Technology, Espoo (Finland); Ahonen, L. [Geological Survey of Finland, Espoo (Finland)

    1998-11-01

    This report presents the evaluation of the uranium solubilities in the reference waters of TILA-99. The behaviour of uranium has been discussed separately in the near-field and far-field conditions. The bentonite/groundwater interactions have been considered in the compositions of the fresh and saline near-field reference waters. The far-field groundwaters` compositions include fresh, brackish, saline and very saline, almost brine-type compositions. The pH and redox conditions, as the main parameters affecting the solubilities, are considered. A literature study was made in order to obtain information on the recent dissolution and leaching experiments of UO{sub 2} and spent fuel. The latest literature includes studies on UO{sub 2} solubility under anoxic conditions, in which the methods for simulating the reducing conditions of deep groundwater have been improved. Studies on natural uraninite and its alteration products give a valuable insight into the long-term behaviour of spent fuel. Also the solubility equilibria for some relevant poorly known uranium minerals have been determined. The solubilities of the selected solubility-limiting phases were calculated using the geochemical code, EQ3/6. The NEA database for uranium was the basis for the modelling. The recently extended and updated SR `97 database was used for comparison. The solubility products for uranophane were taken from the latest literature. The recommended values for solubilities were given after a comparison between the calculated solubilities, experimental information and measured concentrations in natural groundwaters. The experiments include several UO{sub 2} dissolution studies in synthetic groundwaters with compositions close to the reference groundwaters. (author) 81 refs.

  11. Two-electron reductive carbonylation of terminal uranium(V) and uranium(VI) nitrides to cyanate by carbon monoxide.

    Science.gov (United States)

    Cleaves, Peter A; King, David M; Kefalidis, Christos E; Maron, Laurent; Tuna, Floriana; McInnes, Eric J L; McMaster, Jonathan; Lewis, William; Blake, Alexander J; Liddle, Stephen T

    2014-09-22

    Two-electron reductive carbonylation of the uranium(VI) nitride [U(Tren(TIPS))(N)] (2, Tren(TIPS)=N(CH2CH2NSiiPr3)3) with CO gave the uranium(IV) cyanate [U(Tren(TIPS))(NCO)] (3). KC8 reduction of 3 resulted in cyanate dissociation to give [U(Tren(TIPS))] (4) and KNCO, or cyanate retention in [U(Tren(TIPS))(NCO)][K(B15C5)2] (5, B15C5=benzo-15-crown-5 ether) with B15C5. Complexes 5 and 4 and KNCO were also prepared from CO and the uranium(V) nitride [{U(Tren(TIPS))(N)K}2] (6), with or without B15C5, respectively. Complex 5 can be prepared directly from CO and [U(Tren(TIPS))(N)][K(B15C5)2] (7). Notably, 7 reacts with CO much faster than 2. This unprecedented f-block reactivity was modeled theoretically, revealing nucleophilic attack of the π* orbital of CO by the nitride with activation energy barriers of 24.7 and 11.3 kcal mol(-1) for uranium(VI) and uranium(V), respectively. A remarkably simple two-step, two-electron cycle for the conversion of azide to nitride to cyanate using 4, NaN3 and CO is presented.

  12. Kinetics of Uranium Extraction from Uranium Tailings by Oxidative Leaching

    Science.gov (United States)

    Zhang, Biao; Li, Mi; Zhang, Xiaowen; Huang, Jing

    2016-07-01

    Extraction of uranium from uranium tailings by oxidative leaching with hydrogen peroxide (H2O2) was studied. The effects of various extraction factors were investigated to optimize the dissolution conditions, as well as to determine the leaching kinetic parameters. The behavior of H2O2 in the leaching process was determined through scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray diffraction analysis of leaching residues. Results suggest that H2O2 can significantly improve uranium extraction by decomposing the complex gangue structures in uranium tailings and by enhancing the reaction rate between uranium phases and the leaching agent. The extraction kinetics expression was changed from 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)-0.14903(S/L)-1.80435( R o)0.20023 e -1670.93/T t ( t ≥ 5) to 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)0.01382(S/L)-1.83275( R o)0.25763 e -1654.59/T t ( t ≥ 5) by the addition of H2O2 in the leaching process. The use of H2O2 in uranium leaching may help in extracting uranium more efficiently and rapidly from low-uranium-containing ores or tailings.

  13. A literature review of interaction of oxidized uranium species and uranium complexes with soluble organic matter

    Science.gov (United States)

    Jennings, Joan K.; Leventhal, J.S.

    1978-01-01

    Organic material is commonly found associated with uranium ores in sandstone-type deposits. This review of the literature summarizes the classes and separations of naturally occurring organic material but the emphasis is on soluble organic species. The main class of materials of interest is humic substances which are high-molecular-weight complex molecules that are soluble in alkaline solution. These humic substances are able to solubilize (make soluble) minerals and also to complex [by ion exchange and (or) chelation] many cations. The natural process of soil formation results in both mineral decomposition and element complexing by organic species. Uranium in solution, such as ground water, can form many species with other elements or complexes present depending on Eh and pH. In natural systems (oxidizing Eh, pH 5-9) the uranium is usually present as a complex with hydroxide or carbonate. Thermodynamic data for these species are presented. Interacting metals and organic materials have been observed in nature and studied in the laboratory by many workers in diverse scientific disciplines. The results are not easily compared. Measurements of the degree of complexation are reported as equilibrium stability constant determinations. This type of research has been done for Mn, Fe, Cu, Zn, Pb, Ni, Co, Mg, Ca, Al, and to a limited degree for U. The use of Conditional Stability Constants has given quantitative results in some cases. The methods utilized in experiments and calculations are reviewed.

  14. Conversational Narcissism.

    Science.gov (United States)

    Vangelisti, Anita L.; And Others

    1990-01-01

    Examines narcissistic communication and the ways it is exhibited in everyday conversation. Identifies the following behavioral referents: boasting, refocusing the topic of conversation on the self, exaggerating hand and body movements, using a loud tone of voice, and "glazing over" when others speak. Suggests that conversational…

  15. Contentious Conversations

    Science.gov (United States)

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  16. The terrestrial uranium isotope cycle.

    Science.gov (United States)

    Andersen, Morten B; Elliott, Tim; Freymuth, Heye; Sims, Kenneth W W; Niu, Yaoling; Kelley, Katherine A

    2015-01-15

    Changing conditions on the Earth's surface can have a remarkable influence on the composition of its overwhelmingly more massive interior. The global distribution of uranium is a notable example. In early Earth history, the continental crust was enriched in uranium. Yet after the initial rise in atmospheric oxygen, about 2.4 billion years ago, the aqueous mobility of oxidized uranium resulted in its significant transport to the oceans and, ultimately, by means of subduction, back to the mantle. Here we explore the isotopic characteristics of this global uranium cycle. We show that the subducted flux of uranium is isotopically distinct, with high (238)U/(235)U ratios, as a result of alteration processes at the bottom of an oxic ocean. We also find that mid-ocean-ridge basalts (MORBs) have (238)U/(235)U ratios higher than does the bulk Earth, confirming the widespread pollution of the upper mantle with this recycled uranium. Although many ocean island basalts (OIBs) are argued to contain a recycled component, their uranium isotopic compositions do not differ from those of the bulk Earth. Because subducted uranium was probably isotopically unfractionated before full oceanic oxidation, about 600 million years ago, this observation reflects the greater antiquity of OIB sources. Elemental and isotope systematics of uranium in OIBs are strikingly consistent with previous OIB lead model ages, indicating that these mantle reservoirs formed between 2.4 and 1.8 billion years ago. In contrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uranium throughout the upper mantle within the past 600 million years.

  17. Corrosion Evaluation of RERTR Uranium Molybdenum Fuel

    Energy Technology Data Exchange (ETDEWEB)

    A K Wertsching

    2012-09-01

    As part of the National Nuclear Security Agency (NNSA) mandate to replace the use of highly enriched uranium (HEU) fuel for low enriched uranium (LEU) fuel, research into the development of LEU fuel for research reactors has been active since the late 1970’s. Originally referred to as the Reduced Enrichment for Research and Test Reactor (RERTR) program the new effort named Global Threat Reduction Initiative (GTRI) is nearing the goal of replacing the standard aluminum clad dispersion highly enriched uranium aluminide fuel with a new LEU fuel. The five domestic high performance research reactors undergoing this conversion are High Flux Isotope reactor (HFIR), Advanced Test Reactor (ATR), National Institute of Standards and Technology (NIST) Reactor, Missouri University Research Reactor (MURR) and the Massachusetts Institute of Technology Reactor II (MITR-II). The design of these reactors requires a higher neutron flux than other international research reactors, which to this point has posed unique challenges in the design and development of the new mandated LEU fuel. The new design utilizes a monolithic fuel configuration in order to obtain sufficient 235U within the LEU stoichoimetry to maintain the fission reaction within the domestic test reactors. The change from uranium aluminide dispersion fuel type to uranium molybdenum (UMo) monolithic configuration requires examination of possible corrosion issues associated with the new fuel meat. A focused analysis of the UMo fuel under potential corrosion conditions, within the ATR and under aqueous storage indicates a slow and predictable corrosion rate. Additional corrosion testing is recommended for the highest burn-up fuels to confirm observed corrosion rate trends. This corrosion analysis will focus only on the UMo fuel and will address corrosion of ancillary components such as cladding only in terms of how it affects the fuel. The calculations and corrosion scenarios are weighted with a conservative bias to

  18. Analysis of crossover breakpoints yields new insights into the nature of the gene conversion events associated with large NF1 deletions mediated by nonallelic homologous recombination.

    Science.gov (United States)

    Bengesser, Kathrin; Vogt, Julia; Mussotter, Tanja; Mautner, Victor-Felix; Messiaen, Ludwine; Cooper, David N; Kehrer-Sawatzki, Hildegard

    2014-02-01

    Large NF1 deletions are mediated by nonallelic homologous recombination (NAHR). An in-depth analysis of gene conversion operating in the breakpoint-flanking regions of large NF1 deletions was performed to investigate whether the rate of discontinuous gene conversion during NAHR with crossover is increased, as has been previously noted in NAHR-mediated rearrangements. All 20 germline type-1 NF1 deletions analyzed were mediated by NAHR associated with continuous gene conversion within the breakpoint-flanking regions. Continuous gene conversion was also observed in 31/32 type-2 NF1 deletions investigated. In contrast to the meiotic type-1 NF1 deletions, type-2 NF1 deletions are predominantly of post-zygotic origin. Our findings therefore imply that the mitotic as well as the meiotic NAHR intermediates of large NF1 deletions are processed by long-patch mismatch repair (MMR), thereby ensuring gene conversion tract continuity instead of the discontinuous gene conversion that is characteristic of short-patch repair. However, the single type-2 NF1 deletion not exhibiting continuous gene conversion was processed without MMR, yielding two different deletion-bearing chromosomes, which were distinguishable in terms of their breakpoint positions. Our findings indicate that MMR failure during NAHR, followed by post-meiotic/mitotic segregation, has the potential to give rise to somatic mosaicism in human genomic rearrangements by generating breakpoint heterogeneity.

  19. Influence of the Reaction Temperature on the Nature of the Active and Deactivating Species During Methanol-to-Olefins Conversion over H-SAPO-34

    Science.gov (United States)

    2017-01-01

    The selectivity toward lower olefins during the methanol-to-olefins conversion over H-SAPO-34 at reaction temperatures between 573 and 773 K has been studied with a combination of operando UV–vis diffuse reflectance spectroscopy and online gas chromatography. It was found that the selectivity toward propylene increases in the temperature range of 573–623 K, while it decreases in the temperature range of 623–773 K. The high degree of incorporation of olefins, mainly propylene, into the hydrocarbon pool affects the product selectivity at lower reaction temperatures. The nature and dynamics of the active and deactivating hydrocarbon species with increasing reaction temperature were revealed by a non-negative matrix factorization of the time-resolved operando UV–vis diffuse reflectance spectra. The active hydrocarbon pool species consist of mainly highly methylated benzene carbocations at temperatures between 573 and 598 K, of both highly methylated benzene carbocations and methylated naphthalene carbocations at 623 K, and of only methylated naphthalene carbocations at temperatures between 673 and 773 K. The operando spectroscopy results suggest that the nature of the active species also influences the olefin selectivity. In fact, monoenylic and highly methylated benzene carbocations are more selective to the formation of propylene, whereas the formation of the group of low methylated benzene carbocations and methylated naphthalene carbocations at higher reaction temperatures (i.e., 673 and 773 K) favors the formation of ethylene. At reaction temperatures between 573 and 623 K, catalyst deactivation is caused by the gradual filling of the micropores with methylated naphthalene carbocations, while between 623 and 773 K the formation of neutral poly aromatics and phenanthrene/anthracene carbocations are mainly responsible for catalyst deactivation, their respective contribution increasing with increasing reaction temperature. Methanol pulse experiments at

  20. Uranium in soils and water; Uran in Boden und Wasser

    Energy Technology Data Exchange (ETDEWEB)

    Dienemann, Claudia; Utermann, Jens

    2012-07-15

    The report of the Umweltbundesamt (Federal Environmental Agency) on uranium in soils and water covers the following chapters: (1) Introduction. (2) Deposits and properties: Use of uranium; toxic effects on human beings, uranium in ground water and drinking water, uranium in surface waters, uranium in soils, uranium in the air. (3) Legal regulations. (4) Uranium deposits, uranium mining, polluted area recultivation. (5) Diffuse uranium entry in soils and water: uranium insertion due to fertilizers, uranium insertion due to atmospheric precipitation, uranium insertion from the air. (6) Diffuse uranium release from soils and transfer in to the food chain. (7) Conclusions and recommendations.

  1. The supply of the enrichment uranium in Spain. The Uranium Procurement Commission; El abastecimiento de uranio enriquecido en Espana. La Comision de aprovisionamiento de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, G.; Anton, J. A.

    2004-07-01

    The supply of the uranium required for the operation of the spanish nuclear power plants includes the provision of a series of different primary components: uranium concentrates, conversion services and enrichment services. The electric sector has now a variety of offer for these kind of services; but the management of this offer is a complex activity, with multiple connection between successive stages of the process as well as lots of restrictions to be fulfilled with the ultimate goal of having the uranium available on time and at a reasonable cost. Although the management of these activities has been committed to ENUSA, there exists a decision and control group from the side of the Utilities, namely the Uranium Procurement Commission; this article is aimed at giving this group to public knowledge and to show both the importance and the implications of the activities carried out within it. (Author)

  2. SOLVENT EXTRACTION OF URANIUM VALUES

    Science.gov (United States)

    Feder, H.M.; Ader, M.; Ross, L.E.

    1959-02-01

    A process is presented for extracting uranium salt from aqueous acidic solutions by organic solvent extraction. It consists in contacting the uranium bearing solution with a water immiscible dialkylacetamide having at least 8 carbon atoms in the molecule. Mentioned as a preferred extractant is dibutylacetamide. The organic solvent is usually used with a diluent such as kerosene or CCl/sub 4/.

  3. Translocation of uranium from water to foodstuff while cooking

    Energy Technology Data Exchange (ETDEWEB)

    Krishnapriya, K.C.; Baksi, Ananya; Chaudhari, Swathi; Gupta, Soujit Sen; Pradeep, T.

    2015-10-30

    Highlights: • Rice can efficiently uptake uranium from water contaminated with uranyl nitrate hexahydrate (UO{sub 2}(NO{sub 3}) 2.6 H{sub 2}O), while cooking. • Unusual uranium uptake to the extent of about 1000 ppm is observed when rice is cooked in highly concentrated uranium contaminated water (1240 ppm). • Nature of interaction of uranium with carbohydrates is probed using small monosaccharides like glucose and mannose. • Electrospray ionization mass spectrometry showed UO{sub 2}{sup 2+} to be the most stable species in water in such solutions which can form complexes with sugars. • The species (UO{sub 2}{sup 2+}) is also observed in the case of water exposed to the common mineral, uranium oxide (UO{sub 2}) and similar type of complexation is observed with sugars. - Abstract: The present work report the unusual uranium uptake by foodstuff, especially those rich in carbohydrates like rice when they are cooked in water, contaminated with uranium. The major staple diet in South Asia, rice, was chosen to study its interaction with UO{sub 2}{sup 2+}, the active uranium species in water, using inductively coupled plasma mass spectrometry. Highest uptake limit was checked by cooking rice at very high uranium concentration and it was found to be good scavenger of uranium. To gain insight into the mechanism of uptake, direct interaction of UO{sub 2}{sup 2+} with monosaccharides was also studied, using electrospray ionization mass spectrometry taking mannose as a model. The studies have been done with dissolved uranium salt, uranyl nitrate hexahydrate (UO{sub 2}(NO{sub 3}){sub 2}·6H{sub 2}O), as well as the leachate of a stable oxide of uranium, UO{sub 2}(s), both of which exist as UO{sub 2}{sup 2+} in water. Among the eight different rice varieties investigated, Karnataka Ponni showed the maximum uranium uptake whereas unpolished Basmati rice showed the minimum. Interaction with other foodstuffs (potato, carrot, peas, kidney beans and lentils) with and

  4. Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA.

    Science.gov (United States)

    Kayzar, Theresa M; Villa, Adam C; Lobaugh, Megan L; Gaffney, Amy M; Williams, Ross W

    2014-10-01

    The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. The ((234)U)/((238)U) composition of Red Rock Creek is altered downstream of the Juniper Mine. As a result of mine-derived contamination, water ((234)U)/((238)U) ratios are 67% lower than in water upstream of the mine (1.114-1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activity ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041-1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (∼70-80% of uranium in leachable fraction). Contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.

  5. Uranium M x-ray emission spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Keski-Rahkonen, O.; Krause, M.O.

    1977-03-01

    The uranium M x-ray spectrum from a thick metallic target excited by 12-keV electrons was measured by the PAX (photoelectron spectrometry for the analysis of x rays) technique. Energies of the strongest lines were obtained with an accuracy of 0.1 eV using Ag L..beta../sub 1/ and Ag L..cap alpha../sub 1/ as standards. Widths of the uranium lines were obtained by deconvoluting the measured Voigt profiles, and the experimental values were found to agree satisfactorily with McGuire's Hartree-Slater predictions. Natural widths of 4.0(3) and 3.8(3) eV were derived for the M/sub 4/ and M/sub 5/ levels, respectively, and the energies of the M/sub 4/, M/sub 5/, N/sub 2/, and N/sub 3/ levels in uranium metal were determined. Relative intensities of the M lines were measured, and branching ratios were found to be in fair agreement with relativistic Hartree-Slater predictions. The satellite structures of the M..cap alpha../sub 1/ and M..beta.. lines were interpreted in terms of the pertinent multiple-hole configurations. Finally, an approximate analytic expression for the Voigt half-width and its graphical representation are given.

  6. Colloids generation from metallic uranium fuel

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-20

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

  7. Uranium and radium in water samples around the Nikola Tesla B lignite-fired power plant - Obrenovac, Serbia

    Directory of Open Access Journals (Sweden)

    Žunić Zora S.

    2011-01-01

    Full Text Available This paper deals with the analysis of natural radionuclide content in 23 water samples collected in the vicinity of the Nikola Tesla B thermal power plant, Serbia. All samples were analyzed for 226Ra and uranium isotopes (238U, 234U activity using radiochemical methods and alpha spectrometry. Obtained results show that the activity concentrations for uranium and radium in the water around the thermal power plant are low when compared to those from areas across Serbia with their enhanced natural uranium and radium content. No important radiological hazard related to uranium and radium activity stored in heap was found.

  8. Uranium-Series Constraints on Subrepository Water Flow at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    L.A. Neymark; J.B. Paces; S.J. Chipera; D.T. Vaniman

    2006-03-10

    Mineral abundances and whole-rock chemical and uranium-series isotopic compositions were measured in unfractured and rubble core samples from borehole USWSD-9 in the same layers of variably zeolitized tuffs that underlie the proposed nuclear waste repository at Yucca Mountain, Nevada. Uranium concentrations and isotopic compositions also were measured in pore water from core samples from the same rock units and rock leachates representing loosely bound U adsorbed on mineral surfaces or contained in readily soluble secondary minerals. The chemical and isotopic data were used to evaluate differences in water-rock interaction between fractured and unfractured rock and between fracture surfaces and rock matrix. Samples of unfractured and rubble fragments (about 1 centimeter) core and material from fracture surfaces show similar amounts of uranium-series disequilibrium, recording a complex history of sorption and loss of uranium over the past 1 million years. The data indicate that fractures in zeolitized tuffs may not have had greater amounts of water-rock interaction than the rock matrix. The data also show that rock matrix from subrepository units is capable of scavenging uranium with elevated uranium-234/uranium-238 from percolating water and that retardation of radionuclides and dose reduction may be greater than currently credited to this aspect of the natural barrier. Uranium concentrations of pore water and the rock leachates are used to estimate long-term in situ uranium partition coefficient values greater than 7 milliliters per gram.

  9. Depleted uranium analysis in blood by inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Todorov, T.I.; Xu, H.; Ejnik, J.W.; Mullick, F.G.; Squibb, K.; McDiarmid, M.A.; Centeno, J.A.

    2009-01-01

    In this study we report depleted uranium (DU) analysis in whole blood samples. Internal exposure to DU causes increased uranium levels as well as change in the uranium isotopic composition in blood specimen. For identification of DU exposure we used the 235U/238U ratio in blood samples, which ranges from 0.00725 for natural uranium to 0.002 for depleted uranium. Uranium quantification and isotopic composition analysis were performed by inductively coupled plasma mass spectrometry. For method validation we used eight spiked blood samples with known uranium concentrations and isotopic composition. The detection limit for quantification was determined to be 4 ng L-1 uranium in whole blood. The data reproduced within 1-5% RSD and an accuracy of 1-4%. In order to achieve a 235U/238U ratio range of 0.00698-0.00752% with 99.7% confidence limit a minimum whole blood uranium concentration of 60 ng L??1 was required. An additional 10 samples from a cohort of veterans exposed to DU in Gulf War I were analyzed with no knowledge of their medical history. The measured 235U/ 238U ratios in the blood samples were used to identify the presence or absence of DU exposure within this patient group. ?? 2009 The Royal Society of Chemistry.

  10. Uranium removal from aqueous solution by coir pith: equilibrium and kinetic studies.

    Science.gov (United States)

    Parab, Harshala; Joshi, Shreeram; Shenoy, Niyoti; Verma, Rakesh; Lali, Arvind; Sudersanan, M

    2005-07-01

    Basic aspects of uranium adsorption by coir pith have been investigated by batch equilibration. The influence of different experimental parameters such as final solution pH, adsorbent dosage, sorption time, temperature and various concentrations of uranium on uptake were evaluated. Maximum uranium adsorption was observed in the pH range 4.0-6.0. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium. The equilibrium data fitted well to both the equilibrium models in the studied concentration range of uranium (200-800 mg/l) and temperatures (305-336 K). The coir pith exhibited the highest uptake capacity for uranium at 317 K, at the final solution pH value of 4.3 and at the initial uranium concentration of 800 mg/l. The kinetics of the adsorption process followed a second-order adsorption. The adsorbent used proved to be suitable for removal of uranium from aqueous solutions. 0.2 N HCl was effective in uranium desorption. The results indicated that the naturally abundant coir pith of otherwise nuisance value exhibited considerable potential for application in removal of uranium from aqueous solution.

  11. Manhattan Project Technical Series: The Chemistry of Uranium (I)

    Energy Technology Data Exchange (ETDEWEB)

    Rabinowitch, E. I. [Argonne National Lab. (ANL), Argonne, IL (United States); Katz, J. J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    1947-03-10

    This constitutes Chapters 11 through 16, inclusive, of the Survey Volume on Uranium Chemistry prepared for the Manhattan Project Technical Series. Chapters are titled: Uranium Oxides, Sulfides, Selenides, and Tellurides; The Non-Volatile Fluorides of Uranium; Uranium Hexafluoride; Uranium-Chlorine Compounds; Bromides, Iodides, and Pseudo-Halides of Uranium; and Oxyhalides of Uranium.

  12. Synthesis of Uranium nitride powders using metal uranium powders

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N{sup 15} gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work.

  13. Conversion Disorder

    Science.gov (United States)

    ... Recent significant stress or emotional trauma Being female — women are much more likely to develop conversion disorder Having a mental health condition, such as mood or anxiety disorders, dissociative disorder or certain personality disorders Having ...

  14. Conversation Analysis.

    Science.gov (United States)

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  15. Conversation Analysis.

    Science.gov (United States)

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  16. 31 CFR 540.316 - Uranium enrichment.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium enrichment. 540.316 Section... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium enrichment means the process...

  17. Treatment of Uranium and Plutonium solutions generated in Atalante by R and D activities

    Energy Technology Data Exchange (ETDEWEB)

    Lagrave, H.; Beretti, C.; Bros, P. [CEA Rhone Valley Research Center, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France)

    2008-07-01

    The Atalante complex operated by the 'Commissariat a l'Energie Atomique' (Cea) consolidates research programs on actinide chemistry, processing for recycling spent fuel, and fabrication of actinide targets for innovative concepts in future nuclear systems. In order to produce mixed oxide powder containing uranium, plutonium and minor actinides and to deal with increasing flows in the facility, a new shielded line will be built and is expected to be operational by 2012. Its main functions will be to receive, concentrate and store solutions, purify them, ensure co-conversion of actinides and conversion of excess uranium. (authors)

  18. Interaction and transport of actinides in natural clay rock with consideration of humic substances and clay organics. Characterization and quantification of the influence of clay organics on the interaction and diffusion of uranium and americium in the clay. Joint project

    Energy Technology Data Exchange (ETDEWEB)

    Bernhard, Gert [Helmholtz-Zentrum Dresden-Rossendorf e.V. (Germany). Inst. of Radiochemistry; Schmeide, Katja; Joseph, Claudia; Sachs, Susanne; Steudtner, Robin; Raditzky, Bianca; Guenther, Alix

    2011-07-01

    The objective of this project was the study of basic interaction processes in the systems actinide - clay organics - aquifer and actinide - natural clay - clay organics - aquifer. Thus, complexation, redox, sorption and diffusion studies were performed. To evaluate the influence of nitrogen, phosphorus and sulfur containing functional groups of humic acid (HA) on the complexation of actinides in comparison to carboxylic groups, the Am(III) and U(VI) complexation by model ligands was studied by UV-Vis spectroscopy and TRLFS. The results show that Am(III) is mainly coordinated via carboxylic groups, however, probably stabilized by nitrogen groups. The U(VI) complexation is dominated by carboxylic groups, whereas nitrogen and sulfur containing groups play a minor role. Phosphorus containing groups may contribute to the U(VI) complexation by HA, however, due to their low concentration in HA they play only a subordinate role compared to carboxylic groups. Applying synthetic HA with varying sulfur contents (0 to 6.9 wt.%), the role of sulfur functionalities of HA for the U(VI) complexation and Np(V) reduction was studied. The results have shown that sulfur functionalities can be involved in U(VI) humate complexation and act as redox-active sites in HA for the Np(V) reduction. However, due to the low content of sulfur in natural HA, its influence is less pronounced. In the presence of carbonate, the U(VI) complexation by HA was studied in the alkaline pH range by means of cryo-TRLFS (-120 C) and ATR FT-IR spectroscopy. The formation of the ternary UO{sub 2}(CO{sub 3}){sub 2}HA(II){sup 4-} complex was detected. The complex formation constant was determined with log {beta}{sub 0.1} M = 24.57 {+-} 0.17. For aqueous U(VI) citrate and oxalate species, luminescence emission properties were determined by cryo-TRLFS and used to determine stability constants. The existing data base could be validated. The U(VI) complexation by lactate, studied in the temperature range 7 to 65 C

  19. Strategic conversation

    Directory of Open Access Journals (Sweden)

    Nicholas Asher

    2013-08-01

    Full Text Available Models of conversation that rely on a strong notion of cooperation don’t apply to strategic conversation — that is, to conversation where the agents’ motives don’t align, such as courtroom cross examination and political debate. We provide a game-theoretic framework that provides an analysis of both cooperative and strategic conversation. Our analysis features a new notion of safety that applies to implicatures: an implicature is safe when it can be reliably treated as a matter of public record. We explore the safety of implicatures within cooperative and non cooperative settings. We then provide a symbolic model enabling us (i to prove a correspondence result between a characterisation of conversation in terms of an alignment of players’ preferences and one where Gricean principles of cooperative conversation like Sincerity hold, and (ii to show when an implicature is safe and when it is not. http://dx.doi.org/10.3765/sp.6.2 BibTeX info

  20. OXYGEN ISOTOPE FRACTION ATION IN URANIUM OXIDES

    Institute of Scientific and Technical Information of China (English)

    郑永飞

    1995-01-01

    Thermodynamic oxygen isotope factors for uranium oxides have been calculated by means of the modified increment method.The sequence of 18O-enrichment in the uranium oxides with respect to the common rock-forming minerals is predicted as follows:spineluranium blacks≤coffiniteuranium oxides and water and between the uranium oxides and the other minerals have been obtained for 0-1200℃.The theoretical results are applicable to the isotopic geothermometry of uranium ores when pairing with other gangue minerals in hydrothermal uranium deposits.

  1. PURIFICATION OF URANIUM FROM URANIUM/MOLYBDENUM ALLOY

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, R; Ann Visser, A; James Laurinat, J

    2007-10-15

    The Savannah River Site will recycle a nuclear fuel comprised of 90% uranium-10% molybdenum by weight. The process flowsheet calls for dissolution of the material in nitric acid to a uranium concentration of 15-20 g/L without the formation of precipitates. The dissolution will be followed by separation of uranium from molybdenum using solvent extraction with 7.5% tributylphosphate in n-paraffin. Testing with the fuel validated dissolution and solubility data reported in the literature. Batch distribution coefficient measurements were performed for the extraction, strip and wash stages with particular focus on the distribution of molybdenum.

  2. Uranium Enrichment Reduction in the PGSFR Core Design

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chihyung; Hartanto, Donny; Kim, Yonghee [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    Korea is currently developing the so-called Prototype Gen-IV Sodium-cooled Fast Reactor (PGSFR) to investigate and demonstrate the capability of TRU transmutation. However, since fuel recycling technology is still at early development in Korea and also due to lack of experience in burning TRU in a fast reactor, the initial core of PGSFR is loaded with low-enriched uranium (LEU) fuel. Several test assemblies containing TRU fuels are supposed to be irradiated and tested for future TRU fuel developments. The uranium enrichment in the LEU PGSFR core is high, about 19.20%, due to large neutron leakage and low conversion ratio. In this paper, the required uranium enrichment is reduced by replacing the reflector material and modifying the reflector geometry in order to decrease the fuel cost of the LEU PGSFR core. PbO is chosen as the reflector material to replace the current HT9 and an inverted reflector assembly is also investigated in this study. It is shown that longer cycle length, higher fuel burnup and flattening power distribution can be achieved with PbO reflector and enhanced neutron leakage can be handled by the optimization of shielding material or core geometry. PbO reflector with inverted geometry is suggest in this research and by using inverted PbO reflector, core performance can be improved while leakage is negligibly enhanced than conventional pin type reflector assembly. Research about reducing the uranium enrichment more by increasing the uranium content in the uranium fuel which is U-10Zr now or increasing the smeared density which is currently 75% can be considered as a future work. Detailed analysis about multi-batch fuel management should be carried out since currently it is done approximately by using linear reactivity theory. Also, analysis for PGSFR with various reflector materials like LME, liquid lead will be carried out and the chemical reaction of those materials including PbO with sodium should be carefully investigated.

  3. A study of uranium uptake in plants

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, A.; Singh, Surinder; Virk, H.S. (Guru Nanak Dev Univ., Amritsar (India). Dept. of Physics)

    1988-01-01

    A fission track technique has been used to study the uptake of uranium in Tomato Plant. Lexan plastic has been employed as the external detector for recording induced fission tracks due to uranium. The uranium uptake rate is found to increase as the growth proceeds. The uranium concentration is also determined in Phlox, Calendula and Dog Flower, grown under normal conditions. The uranium content is found to vary in different parts of the plants. (author).

  4. Literature review and preliminary analysis of inorganic ammonia pertinent to south Texas uranium in-situ leach

    Energy Technology Data Exchange (ETDEWEB)

    Braswell, J.; Breland, M.; Chang, M.; Farley, J.; Hill, D.; Johnson, D.

    1978-01-01

    The purpose of this report is to review existing literature to aid in the determination of the potential impact of ammonia-containing lixiviants on uranium solution mining aquifers, perform studies based on the available literature, to identify potential ways to protect the groundwaters from ammonia contamination, and to propose further work where data are lacking or needed. The review of the literature includes an analysis and interpretation of the literature as it relates to the solution mining activities. Results focus on the range of geologic and hydrologic conditions representative of South Texas solution minig areas. Other pertinent data sources such as soils and agricultural literature are also reviewed and conclusions extrapolated to the solution mining situation. Specific tasks were: evaluate the potential of natural occurrence and influx of ammonia and/or nitrate species in confined aquifers typical of uranium solution mining sites; find available data on the sorption characteristics of ammonia and nitrates on pure and mixed minerals representative of South Texas geology in solution mining areas; determine applicable selectivity coefficients and kinetic data on sorption and desorption of ammonia on clay minerals; evaluate the potential for natural inorganic ammonia conversion by chemical or other mechanisms in typical solution mining aquifers; review available monitoring data from solution mining operations as it pertains to ammonia adsorption or migration; analyze and provide calculational bases for determining the predicted fate of ammonia under solution mining conditions; recommend continuation programs that focus on areas of uncertainty; provide comprehensive bibliography and abstracts of all pertinent articles.

  5. Evaluation of Uranium Measurements in Water by Various Methods - 13571

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Brian J. [Shaw Environmental and Infrastructure Group, 150 Royall Street, Canton, MA (United States); Workman, Stephen M. [ALS Laboratory Group, Environmental Division, 225 Commerce Drive, Fort Collins, CO 80524 (United States)

    2013-07-01

    In December 2000, EPA amended its drinking water regulations for radionuclides by adding a Maximum Contaminant Level (MCL) for uranium (so called MCL Rule)[1] of 30 micrograms per liter (μg/L). The MCL Rule also included MCL goals of zero for uranium and other radionuclides. Many radioactively contaminated sites must test uranium in wastewater and groundwater to comply with the MCL rule as well as local publicly owned treatment works discharge limitations. This paper addresses the relative sensitivity, accuracy, precision, cost and comparability of two EPA-approved methods for detection of total uranium: inductively plasma/mass spectrometry (ICP-MS) and alpha spectrometry. Both methods are capable of measuring the individual uranium isotopes U-234, U- 235, and U-238 and both methods have been deemed acceptable by EPA. However, the U-238 is by far the primary contributor to the mass-based ICP-MS measurement, especially for naturally-occurring uranium, which contains 99.2745% U-238. An evaluation shall be performed relative to the regulatory requirement promulgated by EPA in December 2000. Data will be garnered from various client sample results measured by ALS Laboratory in Fort Collins, CO. Data shall include method detection limits (MDL), minimum detectable activities (MDA), means and trends in laboratory control sample results, performance evaluation data for all methods, and replicate results. In addition, a comparison will be made of sample analyses results obtained from both alpha spectrometry and the screening method Kinetic Phosphorescence Analysis (KPA) performed at the U.S. Army Corps of Engineers (USACE) FUSRAP Maywood Laboratory (UFML). Many uranium measurements occur in laboratories that only perform radiological analysis. This work is important because it shows that uranium can be measured in radiological as well as stable chemistry laboratories and it provides several criteria as a basis for comparison of two uranium test methods. This data will

  6. On the air-scattering of gamma rays from thick uranium sources

    Science.gov (United States)

    Sakakura, Arthur Y.

    1955-01-01

    Semiquantative interpretation of data from airborne radioactivity surveying requires detailed knowledge of air-scattered gamma-ray intensity at considerable air distances from natural, thick uranium sources. Based on the concept of an elementary source of infinite

  7. Direct Conversion of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Corliss, William R

    1964-01-01

    Topics include: direct versus dynamic energy conversion; laws governing energy conversion; thermoelectricity; thermionic conversion; magnetohydrodynamic conversion; chemical batteries; the fuel cell; solar cells; nuclear batteries; and advanced concepts including ferroelectric conversion and thermomagnetic conversion.

  8. natural

    Directory of Open Access Journals (Sweden)

    Elías Gómez Macías

    2006-01-01

    Full Text Available Partiendo de óxido de magnesio comercial se preparó una suspensión acuosa, la cual se secó y calcinó para conferirle estabilidad térmica. El material, tanto fresco como usado, se caracterizó mediante DRX, área superficial BET y SEM-EPMA. El catalizador mostró una matriz de MgO tipo periclasa con CaO en la superficie. Las pruebas de actividad catalítica se efectuaron en lecho fijo empacado con partículas obtenidas mediante prensado, trituración y clasificación del material. El flujo de reactivos consistió en mezclas gas natural-aire por debajo del límite inferior de inflamabilidad. Para diferentes flujos y temperaturas de entrada de la mezcla reactiva, se midieron las concentraciones de CH4, CO2 y CO en los gases de combustión con un analizador de gases tipo infrarrojo no dispersivo (NDIR. Para alcanzar conversión total de metano se requirió aumentar la temperatura de entrada al lecho a medida que se incrementó el flujo de gases reaccionantes. Los resultados obtenidos permiten desarrollar un sistema de combustión catalítica de bajo costo con un material térmicamente estable, que promueva la alta eficiencia en la combustión de gas natural y elimine los problemas de estabilidad, seguridad y de impacto ambiental negativo inherentes a los procesos de combustión térmica convencional.

  9. SEPARATION OF URANIUM FROM THORIUM

    Science.gov (United States)

    Hellman, N.N.

    1959-07-01

    A process is presented for separating uranium from thorium wherein the ratio of thorium to uranium is between 100 to 10,000. According to the invention the thoriumuranium mixture is dissolved in nitric acid, and the solution is prepared so as to obtain the desired concentration within a critical range of from 4 to 8 N with regard to the total nitrate due to thorium nitrate, with or without nitric acid or any nitrate salting out agent. The solution is then contacted with an ether, such as diethyl ether, whereby uranium is extracted into ihe organic phase while thorium remains in the aqueous phase.

  10. Pyrophoric behaviour of uranium hydride and uranium powders

    Energy Technology Data Exchange (ETDEWEB)

    Le Guyadec, F., E-mail: fabienne.leguyadec@cea.f [CEA Marcoule DEN/DTEC/SDTC, 30207 Bagnols sur Ceze, BP 17171 (France); Genin, X.; Bayle, J.P. [CEA Marcoule DEN/DTEC/SDTC, 30207 Bagnols sur Ceze, BP 17171 (France); Dugne, O. [DEN/DTEC/SGCS, 30207 Bagnols sur Ceze, BP 17171 (France); Duhart-Barone, A.; Ablitzer, C. [CEA Cadarache DEN/DEC/SPUA, 13108 St. Paul lez Durance (France)

    2010-01-31

    Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (<0.5 wt.%) was obtained by heat treatment at low temperature in flowing Ar/5%H{sub 2}. Pure uranium powder was obtained by dehydration in flowing pure argon. Those fine powders showed spontaneous ignition at room temperature in air. An in situ CCD-camera displayed ignition associated with powder temperature measurement. Characterization of powders before and after ignition was performed by XRD measurements and SEM observations. Oxidation mechanisms are proposed.

  11. Filiform-mode hydride corrosion of uranium surfaces

    Science.gov (United States)

    Hill, M. A.; Schulze, R. K.; Bingert, J. F.; Field, R. D.; McCabe, R. J.; Papin, P. A.

    2013-11-01

    Hydride nucleation and growth has previously been studied in uranium with an air-formed oxide. Preferred directional growth of uranium hydride has not been observed, presumably due to the constraint of the oxide layer and/or the presence of a surface layer distorted by mechanical grinding and polishing. Instead, hydrides typically first form as subsurface blisters that do not exhibit preferred growth directionality. By eliminating the strained surface layer through electropolishing, removing the natural oxide through ion sputtering, avoiding exposure of the uranium to air, and then exposing uranium to high purity hydrogen in an environmental cell, hydride growth patterns emerge that correspond to defect structures within the microstructure. These hydride growth patterns are similar to filiform corrosion, a type of corrosion that frequently forms under thin protective films. This work describes the first reported observation of filiform-like corrosion in uranium. The uranium hydride initiates at defects, but grows into filaments up to 20 μm wide, and tends to form in straight lines, largely propagating along twin boundaries. Propagation is driven by hydrogen reaction at the filament head, promoted by more efficient delivery of reactant. However, this phenomenon does not involve an electrochemical process associated with conventional filiform corrosion and is therefore described as filiform-like. Hydride growth was observed using optical microscopy for a period of nearly three years. Sample characterization included automated electron backscatter diffraction (EBSD) measurements to determine growth directions. Observation of this anomalous hydride growth provides clues as to the mechanisms operating in uranium hydriding for more conventionally prepared sample surfaces.

  12. Uranium isotope separation from 1941 to the present

    Energy Technology Data Exchange (ETDEWEB)

    Maier-Komor, Peter, E-mail: Peter@Maier-Komor.d [Retired from Physik-Department E12, Technische Universitaet Muenchen, D-85747 Garching (Germany)

    2010-02-11

    Uranium isotope separation was the key development for the preparation of highly enriched isotopes in general and thus became the seed for target development and preparation for nuclear and applied physics. In 1941 (year of birth of the author) large-scale development for uranium isotope separation was started after the US authorities were warned that NAZI Germany had started its program for enrichment of uranium and might have confiscated all uranium and uranium mines in their sphere of influence. Within the framework of the Manhattan Projects the first electromagnetic mass separators (Calutrons) were installed and further developed for high throughput. The military aim of the Navy Department was to develop nuclear propulsion for submarines with practically unlimited range. Parallel to this the army worked on the development of the atomic bomb. Also in 1941 plutonium was discovered and the production of {sup 239}Pu was included into the atomic bomb program. {sup 235}U enrichment starting with natural uranium was performed in two steps with different techniques of mass separation in Oak Ridge. The first step was gas diffusion which was limited to low enrichment. The second step for high enrichment was performed with electromagnetic mass spectrometers (Calutrons). The theory for the much more effective enrichment with centrifugal separation was developed also during the Second World War, but technical problems e.g. development of high speed ball and needle bearings could not be solved before the end of the war. Spying accelerated the development of uranium separation in the Soviet Union, but also later in China, India, Pakistan, Iran and Iraq. In this paper, the physical and chemical procedures are outlined which lead to the success of the project. Some security aspects and Non-Proliferation measures are discussed.

  13. Validation of the WATEQ4 geochemical model for uranium

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, K.M.; Jenne, E.A.; Deutsch, W.J.

    1983-09-01

    As part of the Geochemical Modeling and Nuclide/Rock/Groundwater Interactions Studies Program, a study was conducted to partially validate the WATEQ4 aqueous speciation-solubility geochemical model for uranium. The solubility controls determined with the WATEQ4 geochemical model were in excellent agreement with those laboratory studies in which the solids schoepite (UO/sub 2/(OH)/sub 2/ . H/sub 2/O), UO/sub 2/(OH)/sub 2/, and rutherfordine ((UO/sub 2/CO/sub 3/) were identified as actual solubility controls for uranium. The results of modeling solution analyses from laboratory studies of uranyl phosphate solids, however, identified possible errors in the characterization of solids in the original solubility experiments. As part of this study, significant deficiencies in the WATEQ4 thermodynamic data base for uranium solutes and solids were corrected. Revisions included recalculation of selected uranium reactions. Additionally, thermodynamic data for the hydroxyl complexes of U(VI), including anionic (VI) species, were evaluated (to the extent permitted by the available data). Vanadium reactions were also added to the thermodynamic data base because uranium-vanadium solids can exist in natural ground-water systems. This study is only a partial validation of the WATEQ4 geochemical model because the available laboratory solubility studies do not cover the range of solid phases, alkaline pH values, and concentrations of inorganic complexing ligands needed to evaluate the potential solubility of uranium in ground waters associated with various proposed nuclear waste repositories. Further validation of this or other geochemical models for uranium will require careful determinations of uraninite solubility over the pH range of 7 to 10 under highly reducing conditions and of uranyl hydroxide and phosphate solubilities over the pH range of 7 to 10 under oxygenated conditions.

  14. Uranium isotope separation from 1941 to the present

    Science.gov (United States)

    Maier-Komor, Peter

    2010-02-01

    Uranium isotope separation was the key development for the preparation of highly enriched isotopes in general and thus became the seed for target development and preparation for nuclear and applied physics. In 1941 (year of birth of the author) large-scale development for uranium isotope separation was started after the US authorities were warned that NAZI Germany had started its program for enrichment of uranium and might have confiscated all uranium and uranium mines in their sphere of influence. Within the framework of the Manhattan Projects the first electromagnetic mass separators (Calutrons) were installed and further developed for high throughput. The military aim of the Navy Department was to develop nuclear propulsion for submarines with practically unlimited range. Parallel to this the army worked on the development of the atomic bomb. Also in 1941 plutonium was discovered and the production of 239Pu was included into the atomic bomb program. 235U enrichment starting with natural uranium was performed in two steps with different techniques of mass separation in Oak Ridge. The first step was gas diffusion which was limited to low enrichment. The second step for high enrichment was performed with electromagnetic mass spectrometers (Calutrons). The theory for the much more effective enrichment with centrifugal separation was developed also during the Second World War, but technical problems e.g. development of high speed ball and needle bearings could not be solved before the end of the war. Spying accelerated the development of uranium separation in the Soviet Union, but also later in China, India, Pakistan, Iran and Iraq. In this paper, the physical and chemical procedures are outlined which lead to the success of the project. Some security aspects and Non-Proliferation measures are discussed.

  15. Meeting of the French geological society - Uranium: geology, geophysics, chemistry. Book of abstracts; Reunion de la Societe Geologique de France - Uranium: geologie, geophysique, chimie. Recueil des resumes

    Energy Technology Data Exchange (ETDEWEB)

    Zakari, A.A.; Mima, S.; Bidaud, A.; Criqui, P.; Menanteau, P.; David, S.; Pagel, M.; Chagnes, A.; Cote, G.; Courtaud, B.; Thiry, J.; Miehe, J.M.; Gilbert, F.; Cuney, M.; Bruneton, P.; Ewington, D.; Vautrin-Ul, C.; Cannizzo, C.; Betelu, S.; Chausse, A.; Ly, J.; Bourgeois, D.; Maynadie, J.; Meyer, D.; Clavier, N.; Costin, D.T.; Cretaz, F.; Szenknect, S.; Ravaux, J.; Poinssot, C.; Dacheux, N.; Durupt, N.; Blanvillain, J.J.; Geffroy, F.; Aparicio, B.; Dubessy, J.; Nguyen-Trung, C.; Robert, P.; Uri, F.; Beaufort, D.; Lescuyer, J.L.; Morichon, E.; Allard, T.; Milesi, J.P.; Richard, A.; Rozsypal, C.; Mercadier, J.; Banks, D.A.; Boiron, M.C.; Cathelineau, M.; Dardel, J.; Billon, S.; Patrier, P.; Wattinne, A.; Vanderhaeghe, O.; Fabre, C.; Castillo, M.; Salvi, S.; Beziat, D.; Williams-Jones, A.E.; Trap, P.; Durand, C.; Goncalves, P.; Marquer, D.; Feybesse, J.L.; Richard, Y.; Orberger, B.; Hofmann, A.; Megneng, M.; Orberger, B.; Bouttemy, M.; Vigneron, J.; Etcheberry, A.; Perdicakis, M.; Prignon, N.; Toe, W.; Andre-Mayer, A.S.; Eglinger, A.; Jordaan, T.; Hocquet, S.; Ledru, P.; Selezneva, V.; Vendryes, G.; Lach, P.; Cuney, M.; Mercadier, J.; Brouand, M.; Duran, C.; Seydoux-Guillaume, A.M.; Bingen, B.; Parseval, P. de; Guillaume, D.; Bosse, V.; Paquette, J.L.; Ingrin, J.; Montel, J.M.; Giot, R.; Maucotel, F.; Hubert, S.; Gautheron, C.; Tassan-Got, L.; Pagel, M.; Barbarand, J.; Cuney, M.; Lach, P.; Bonhoure, J.; Leisen, M.; Kister, P.; Salaun, A.; Villemant, B.; Gerard, M.; Komorowski, J.C.; Michel, A.; Riegler, T.; Tartese, R.; Boulvais, P.; Poujols, M.; Gloaguen, E.; Mazzanti, M.; Mougel, V.; Nocton, G.; Biswas, B.; Pecaut, J.; Othmane, G.; Menguy, N.; Vercouter, T.; Morin, G.; Galoisy, L.; Calas, G.; Fayek, M.

    2010-11-15

    -temperature, and metallogenic provinces; 21 - Magmatic-hydrothermal transition in the Roessing pegmatite: implications for uranium mineralisation; 22 - Deformation and partial fusion of a Archean-paleo-Proterozoic crust: implication on uraniferous ores mobilization and deposition, Torngats orogenesis, Ungava bay; 23 - Black chert pebbles of the Pongola basin conglomerates ({approx}2, 9 Ga - South Africa): a potential uranium source?; 24 - origin and evolution of detrital pyrites in meso-Archean conglomerates (3.08-2.64 Ga) of South Africa: uranium source or trap?; 25 - Experimental study of U(VI) carbonates with respect to 3 parameters: pH, carbonate concentration, temperature, using vibrational (Raman, FTIR, ATR) and optical (UV-visible) spectroscopy; 26 - Nature and significance of the contact between the Abbabis gneiss complex and the meta-sedimentary sequences of the Damara orogenic belt; 27 - Metallogenic potentialities of Proterozoic orogenic belts accreted to Archean basements: the Damara/Lufilien orogen - Namibia and Zambia; 28 - Contribution of the Geological Exploration to the development of the KATCO ISR mine - Chu-Sarysu basin, Kazakhstan; 29 - Remarks about some remarkable events which occurred during the Francevillien formation; 30 - Geochemical signature of different mineral phases obtained by ICP-MS laser ablation (trace elements and rare earths): Application Uranium deposits; 31 - Role of fluids and irradiation in complex pegmatite euxenite/zircon assemblies from Norway and their U-Pb geochronological consequences; 32 - Mechanical modeling of rupture around metamictic minerals; 33 - Helium diffusion in apatite: Effect alpha recoil-linked damages; 34 - Rare earth spectra in uranium oxides: a marker of the uranium deposit type; 35 - Rare earths: tracers of uranium behaviour during acid sulphated hydrothermal weathering - the Guadeloupe example; 36 - What metallogenic model for the Kiggavik-Andrew Lake trend? Nunavut, Canada; 37 - Uranium mobility in the Southern

  16. Selective uptake of uranium and thorium by some vegetables

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, A.M. [Universiti Teknologi Malaysia, Johor Bahru (Malaysia); Ghazali, Z.; Rahman, S.A. [Malaysian Inst. for Nuclear Technology and Research, Bangi (Malaysia)

    1996-12-31

    Uranium and thorium are trace elements in the actinide series found naturally in the atmosphere and can enter the human body through ingestion of food or by drinking. To establish baseline information for current and future environmental assessment due to pollution, especially in foodstuff, by heavy and trace metals, biological samples such as locally grown vegetables were analyzed for uranium and thorium contents. The terrain in most parts of the Malaysian peninsula consists of monazite-bearing rocks or soil that can be found extensively in areas related to tin-mining operations. Abandoned mining areas provide suitable sites for vegetable cultivation where most vegetables in the lowlands are grown.

  17. Diversity and Characterization of Sulfate-Reducing Bacteria in Groundwater at a Uranium Mill Tailings Site

    OpenAIRE

    Chang, Yun-Juan; Peacock, Aaron D.; Long, Philip E; Stephen, John R.; McKinley, James P.; Macnaughton, Sarah J.; Hussain, A. K. M. Anwar; Saxton, Arnold M.; White, David C.

    2001-01-01

    Microbially mediated reduction and immobilization of U(VI) to U(IV) plays a role in both natural attenuation and accelerated bioremediation of uranium-contaminated sites. To realize bioremediation potential and accurately predict natural attenuation, it is important to first understand the microbial diversity of such sites. In this paper, the distribution of sulfate-reducing bacteria (SRB) in contaminated groundwater associated with a uranium mill tailings disposal site at Shiprock, N.Mex., w...

  18. Characterization of Uranium Contamination, Transport, and Remediation at Rocky Flats - Across Remediation into Post-Closure

    Science.gov (United States)

    Janecky, D. R.; Boylan, J.; Murrell, M. T.

    2009-12-01

    The Rocky Flats Site is a former nuclear weapons production facility approximately 16 miles northwest of Denver, Colorado. Built in 1952 and operated by the Atomic Energy Commission and then Department of Energy, the Site was remediated and closed in 2005, and is currently undergoing long-term surveillance and monitoring by the DOE Office of Legacy Management. Areas of contamination resulted from roughly fifty years of operation. Of greatest interest, surface soils were contaminated with plutonium, americium, and uranium; groundwater was contaminated with chlorinated solvents, uranium, and nitrates; and surface waters, as recipients of runoff and shallow groundwater discharge, have been contaminated by transport from both regimes. A region of economic mineralization that has been referred to as the Colorado Mineral Belt is nearby, and the Schwartzwalder uranium mine is approximately five miles upgradient of the Site. Background uranium concentrations are therefore elevated in many areas. Weapons-related activities included work with enriched and depleted uranium, contributing anthropogenic content to the environment. Using high-resolution isotopic analyses, Site-related contamination can be distinguished from natural uranium in water samples. This has been instrumental in defining remedy components, and long-term monitoring and surveillance strategies. Rocky Flats hydrology interlinks surface waters and shallow groundwater (which is very limited in volume and vertical and horizontal extent). Surface water transport pathways include several streams, constructed ponds, and facility surfaces. Shallow groundwater has no demonstrated connection to deep aquifers, and includes natural preferential pathways resulting primarily from porosity in the Rocky Flats alluvium, weathered bedrock, and discontinuous sandstones. In addition, building footings, drains, trenches, and remedial systems provide pathways for transport at the site. Removal of impermeable surfaces (buildings

  19. Uranium Isotope Ratios in Modern and Precambrian Soils

    Science.gov (United States)

    DeCorte, B.; Planavsky, N.; Wang, X.; Auerbach, D. J.; Knudsen, A. C.

    2015-12-01

    Uranium isotopes (δ238U values) are an emerging paleoredox proxy that can help to better understand the redox evolution of Earth's surface environment. Recently, uranium isotopes have been used to reconstruct ocean and atmospheric redox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011; Kendall et al., 2013; Dahl et al., 2014). However, to date, there have not been studies on paleosols, despite that paleosols are, arguably better suited to directly tracking the redox conditions of the atmosphere. Sedimentary δ238U variability requires the formation of the soluble, oxidized form of U, U(VI). The formation of U(VI) is generally thought to require oxygen levels orders of magnitude higher than prebiotic levels. Without significant U mobility, it would have been impossible to develop isotopically distinct pools of uranium in ancient Earth environments. Conversely, an active U redox cycle leads to significant variability in δ238U values. Here we present a temporally and geographically expansive uranium isotope record from paleosols and modern soils to better constrain atmospheric oxygen levels during the Precambrian. Preliminary U isotope measurements of paleosols are unfractionated (relative to igneous rocks), possibly because of limited fractionation during oxidation (e.g., {Wang, 2015 #478}) or insufficient atmospheric oxygen levels to oxidize U(IV)-bearing minerals in the bedrock. Further U isotope measurements of paleosols with comparison to modern soils will resolve this issue.

  20. Uranium hexafluoride bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, S.L.

    1988-01-01

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

  1. Effects of heat treatments on the thermal diffusivity of Uranium-Molybdenum alloy

    Science.gov (United States)

    Camarano, D. M.; Mansur, F. A.; Santos, A. M. M.; Ferraz, W. B.; Pedrosa, T. A.

    2016-07-01

    U-Mo alloys are the most investigated nuclear fuel material to be used in research reactors. The addition of molybdenum stabilizes the gamma phase of uranium and increases its melting point. A research program under development at Nuclear Technology Development Center (CDTN) aims the obtaining of uranium-molybdenum alloys to enable the high enriched uranium (HEU) to low enriched uranium (LEU) conversions. U-Mo ingots with 10% by weight were induction melted and heat treated at 300 °C for 72 h, 120 h and 240 h. Thermal diffusivity was determined by the laser flash method and thermal quadrupole method, from room temperature to 300 oC and 400oC. It was observed that the thermal diffusivity tends to increase with increasing temperature.

  2. Standard test methods for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 These test methods cover procedures for subsampling and for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride UF6. Most of these test methods are in routine use to determine conformance to UF6 specifications in the Enrichment and Conversion Facilities. 1.2 The analytical procedures in this document appear in the following order: Note 1—Subcommittee C26.05 will confer with C26.02 concerning the renumbered section in Test Methods C761 to determine how concerns with renumbering these sections, as analytical methods are replaced with stand-alone analytical methods, are best addressed in subsequent publications. Sections Subsampling of Uranium Hexafluoride 7 - 10 Gravimetric Determination of Uranium 11 - 19 Titrimetric Determination of Uranium 20 Preparation of High-Purity U3O 8 21 Isotopic Analysis 22 Isotopic Analysis by Double-Standard Mass-Spectrometer Method 23 - 29 Determination of Hydrocarbons, Chlorocarbons, and Partially Substitut...

  3. Conversing Life: An Autoethnographic Construction

    Science.gov (United States)

    Hoelson, Christopher N.; Burton, Rod

    2012-01-01

    This autoethnography is a constructed account of a co-exploration into the nature and effects of a longitudinal dyadic conversation process from a relational constructionist perspective. The conversations, between me as participant autoethnographer and a co-participant, aimed at maximising personal learning for both. Through co-created contexts of…

  4. Bio-/Photo-Chemical Separation and Recovery of Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Francis,A.J.; Dodge, C.J.

    2008-03-12

    Citric acid forms bidentate, tridentate, binuclear or polynuclear species with transition metals and actinides. Biodegradation of metal citrate complexes is influenced by the type of complex formed with metal ions. While bidentate complexes are readily biodegraded, tridentate, binuclear and polynuclear species are recalcitrant. Likewise certain transition metals and actinides are photochemically active in the presence of organic acids. Although the uranyl citrate complex is not biodegraded, in the presence of visible light it undergoes photochemical oxidation/reduction reactions which result in the precipitation of uranium as UO{sub 3} {center_dot} H{sub 2}O. Consequently, we developed a process where uranium is extracted from contaminated soils and wastes by citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, whereas uranyl citrate which is recalcitrant remains in solution. Photochemical degradation of the uranium citrate complex resulted in the precipitation of uranium. Thus the toxic metals and uranium in mixed waste are recovered in separate fractions for recycling or for disposal. The use of naturally-occurring compounds and the combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in cost.

  5. Yalina booster subcritical assembly performance with low enriched uranium fuel

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto; Gohar, Yousry, E-mail: alby@anl.gov [Argonne National Laboratory, Lemont, IL (United States)

    2011-07-01

    The YALINA Booster facility is a subcritical assembly located in Minsk, Belarus. The facility has special features that result in fast and thermal neutron spectra in different zones. The fast zone of the assembly uses a lead matrix and uranium fuels with different enrichments: 90% and 36%, 36%, or 21%. The thermal zone of the assembly contains 10% enriched uranium fuel in a polyethylene matrix. This study discusses the performance of the three YALINA Booster configurations with the different fuel enrichments. In order to maintain the same subcriticality level in the three configurations, the number of fuel rods in the thermal zone is increased as the uranium fuel enrichment in the fast zone is decreased. The maximum number of fuel rods that can be loaded in the thermal zone is about 1185. Consequently, the neutron multiplication of the configuration with 21% enriched uranium fuel in the fast zone is enhanced by changing the position of the boron carbide and the natural uranium absorber rods, located between the fast and the thermal zones, to form an annular rather than a square arrangement. (author)

  6. Study on `Tannix` an absorbent for heavy metals including uranium

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yasuo [Mitsubishi Nuclear Fuel Co. Ltd., Tokyo (Japan)

    1997-09-01

    To treat radioactive wastes including uranium and transuranic elements such as plutonium, americium etc., development of an absorbent which can be used to absorb and isolate these elements without producing secondary wastes after treatment was attempted. And an absorbent has been successfully developed by polymerizing tannin, a natural product. It is known that tannin binds heavy metals including uranium resulting to produce their precipitates. There are some reports suggesting its absorption ability for uranium. However, tannin has not been used to isolate a heavy metal from a solution because it is soluble in water. Here, insolubilization of tannin was attempted and a manufacturing method for a gelatinized insoluble tannin named as ``Tannix`` was established. Wattle tannin extracted from Mimosa pudica produced in Africa was dissolved in an alkaline solution and gelatinized by heating after the addition of formalin. Thus obtained insoluble tannin was used after crushing and sieving. This product, ``Tannix`` was able to absorb more than 99% of uranium in the waste. And the absorbed Tannin could be degraded by incineration even at a low temperature, leaving only uranium, but not producing any secondary product. (M.N.)

  7. Chemometric approach for prediction of uranium pathways in the soil

    Energy Technology Data Exchange (ETDEWEB)

    Stojanovic, Mirjana; Nihajlovic, Marija; Petrovic, Jelena; Petrovic, Marija; Sostaric, Tanja; Milojkovic, Jelena [Inst. for Technology of Nuclear and Other Mineral Raw Materials, Belgrad (Serbia); Pezo, Lato [Univ. Belgrad (Serbia). Inst. of General and Physical Chemistry

    2014-10-01

    Understanding the effect of soil parameters (pH, Eh and organic and inorganic ligands availability) on uranium mobility under different geochemical conditions is fundamental for reliable prediction of its behaviour and fate in the environment. In this study, the impact of total and available phosphorus content, humus and acidity of Serbian agricultural soils on the content of total and available uranium were evaluated by Response Surface Methodology (RSM), second order polynomial regression models (SOPs) and artificial neural networks (ANNs). The performance of ANNs was compared with the performance of SOPs and experimental results. SOPs showed high coefficients of determination (0.785-0.956), while ANN model performed high prediction accuracy: 0.8893-0.904. According to the results, total and available uranium content in the soil were mostly affected by pH, statistically significant at p < 0.05 level. For the same responses the total phosphorus was found to be also very influential, statistically significant at p < 0.05 and p < 0.10 levels. The impact of available phosphorus and humus was much more influential on total and available uranium content, compared to total phosphorus content. Proposed chemometric approach will be very helpful in preserving the natural resources and practical application for risk assessment modeling of uranium environmental pathways.

  8. Towards a genetic classification of uranium deposits; Vers une classification genetique des gisements d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Cuney, M. [G2R, Nancy Universite, CNRS, CREGU, 54 - Vandoeuvre les Nancy (France)

    2009-07-01

    As the IAEA's uranium deposit classification is based on the deposit nature and morphology, some deposits which have been formed by very different genetic processes and located in very different geological environments, are grouped according to this classification. In order to build up a reliable genetic classification based on the mechanism at the origin of the formation of the deposit, the author presents the five main categories according to which uranium deposits can be classified: magmatic, hydrothermal, evapotranspiration, syn-sedimentary, and infiltration of meteoric water

  9. Femtosecond Laser Ablation Multicollector ICPMS Analysis of Uranium Isotopes in NIST Glass

    Energy Technology Data Exchange (ETDEWEB)

    Duffin, Andrew M.; Springer, Kellen WE; Ward, Jesse D.; Jarman, Kenneth D.; Robinson, John W.; Endres, Mackenzie C.; Hart, Garret L.; Gonzalez, Jhanis J.; Oropeza, Dayana; Russo, Richard; Willingham, David G.; Naes, Benjamin E.; Fahey, Albert J.; Eiden, Gregory C.

    2015-02-06

    We have utilized femtosecond laser ablation coupled to multi-collector inductively couple plasma mass spectrometry to measure the uranium isotopic content of NIST 61x (x=0,2,4,6) glasses. The uranium content of these glasses is a linear two-component mixing between isotopically natural uranium and the isotopically depleted spike used in preparing the glasses. Laser ablation results match extremely well, generally within a few ppm, with solution analysis following sample dissolution and chemical separation. In addition to isotopic data, sample utilization efficiency measurements indicate that over 1% of ablated uranium atoms reach a mass spectrometer detector, making this technique extremely efficient. Laser sampling also allows for spatial analysis and our data indicate that rare uranium concentration inhomogeneities exist in NIST 616 glass.

  10. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A.; Tome, F.V.; Diaz Bejarano, J.; Jurado Vargas, M. (Dept. de Fisica, Univ. Extremadura, Badajoz (Spain))

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope ({sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium. (orig.).

  11. Occurrence of uranium in rocks of the intrusive complex at Ekiek Creek, western Alaska

    Science.gov (United States)

    Wallace, Alan R.

    1979-01-01

    Uranium in the Ekiek Creek Complex of western Alaska is related to a niobium-rich pyrochlore in the nepheline syenite of the complex. The complex consists of an aegirine-phlogopite pyroxenite that has been intruded and partly replaced by nepheline syenite. The contact zone between the two igneous units varies from a sharp contact to a diffuse zone where the pyroxenite has been metasomatically replaced by the syenite. The entire complex was intruded into an older Cretaceous monzonite. The pyrochlore occurs as an accessory mineral in the syenite, and is visible in rocks containing over 50 ppm uranium. Chemical analyses indicate that, in all samples of syenite, there is a positive correlation between uranium and niobium; this suggests that the uranium-pyrochlore association persists even when pyrochlore is not readily visible in thin section. The small amount of pyrochlore, and its refractory nature, make the complex an unfavorable source for secondary uranium leaching or heavy-mineral concentration.

  12. Uranium from German nuclear power projects of the 1940s - a nuclear forensic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Klaus; Wallenius, Maria; Luetzenkirchen, Klaus; Horta, Joan; Nicholl, Adrian; Rasmussen, Gert; Belle, Pieter van; Varga, Zsolt [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Karlsruhe (Germany); Buda, Razvan; Erdmann, Nicole [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Karlsruhe (Germany); Institut fuer Kernchemie, Universitaet Mainz (Germany); Kratz, Jens-Volker; Trautmann, Norbert [Institut fuer Kernchemie, Universitaet Mainz (Germany); Fifield, L. Keith; Tims, Stephen G. [Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT (Australia); Froehlich, Michaela B. [Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT (Australia); Universitaet Wien, Fakultaet fuer Chemie, Institut fuer Anorganische Chemie, Vienna (Austria); Steier, Peter [Universitaet Wien, Fakultaet fuer Physik, Isotopenforschung und Kernphysik, Vienna (Austria)

    2015-11-02

    Here we present a nuclear forensic study of uranium from German nuclear projects which used different geometries of metallic uranium fuel. Through measurement of the {sup 230}Th/{sup 234}U ratio, we could determine that the material had been produced in the period from 1940 to 1943. To determine the geographical origin of the uranium, the rare-earth-element content and the {sup 87}Sr/{sup 86}Sr ratio were measured. The results provide evidence that the uranium was mined in the Czech Republic. Trace amounts of {sup 236}U and {sup 239}Pu were detected at the level of their natural abundance, which indicates that the uranium fuel was not exposed to any major neutron fluence. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Uranium in the Surrounding of San Marcos-Sacramento River Environment (Chihuahua, Mexico)

    Science.gov (United States)

    Rentería-Villalobos, Marusia; Cortés, Manuel Reyes; Mantero, Juan; Manjón, Guillermo; García-Tenorio, Rafael; Herrera, Eduardo; Montero-Cabrera, Maria Elena

    2012-01-01

    The main interest of this study is to assess whether uranium deposits located in the San Marcos outcrops (NW of Chihuahua City, Mexico) could be considered as a source of U-isotopes in its surrounding environment. Uranium activity concentrations were determined in biota, ground, and surface water by either alpha or liquid scintillation spectrometries. Major ions were analyzed by ICP-OES in surface water and its suspended matter. For determining uranium activity in biota, samples were divided in parts. The results have shown a possible lixiviation and infiltration of uranium from geological substrate into the ground and surface water, and consequently, a transfer to biota. Calculated annual effective doses by ingestion suggest that U-isotopes in biota could not negligibly contribute to the neighboring population dose. By all these considerations, it is concluded that in this zone there is natural enhancement of uranium in all environmental samples analyzed in the present work. PMID:22536148

  14. Uranium in the Surrounding of San Marcos-Sacramento River Environment (Chihuahua, Mexico

    Directory of Open Access Journals (Sweden)

    Marusia Rentería-Villalobos

    2012-01-01

    Full Text Available The main interest of this study is to assess whether uranium deposits located in the San Marcos outcrops (NW of Chihuahua City, Mexico could be considered as a source of U-isotopes in its surrounding environment. Uranium activity concentrations were determined in biota, ground, and surface water by either alpha or liquid scintillation spectrometries. Major ions were analyzed by ICP-OES in surface water and its suspended matter. For determining uranium activity in biota, samples were divided in parts. The results have shown a possible lixiviation and infiltration of uranium from geological substrate into the ground and surface water, and consequently, a transfer to biota. Calculated annual effective doses by ingestion suggest that U-isotopes in biota could not negligibly contribute to the neighboring population dose. By all these considerations, it is concluded that in this zone there is natural enhancement of uranium in all environmental samples analyzed in the present work.

  15. Uranium in the surrounding of San Marcos-Sacramento River environment (Chihuahua, Mexico).

    Science.gov (United States)

    Rentería-Villalobos, Marusia; Cortés, Manuel Reyes; Mantero, Juan; Manjón, Guillermo; García-Tenorio, Rafael; Herrera, Eduardo; Montero-Cabrera, Maria Elena

    2012-01-01

    The main interest of this study is to assess whether uranium deposits located in the San Marcos outcrops (NW of Chihuahua City, Mexico) could be considered as a source of U-isotopes in its surrounding environment. Uranium activity concentrations were determined in biota, ground, and surface water by either alpha or liquid scintillation spectrometries. Major ions were analyzed by ICP-OES in surface water and its suspended matter. For determining uranium activity in biota, samples were divided in parts. The results have shown a possible lixiviation and infiltration of uranium from geological substrate into the ground and surface water, and consequently, a transfer to biota. Calculated annual effective doses by ingestion suggest that U-isotopes in biota could not negligibly contribute to the neighboring population dose. By all these considerations, it is concluded that in this zone there is natural enhancement of uranium in all environmental samples analyzed in the present work.

  16. A study on possible use of Urtica dioica (common nettle) plants as uranium ((234)U, (238)U) contamination bioindicator near phosphogypsum stockpile.

    Science.gov (United States)

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    The aim of this study was to determine uranium concentrations in common nettle (Urtica dioica) plants and corresponding soils samples which were collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The uranium concentrations in roots depended on its concentrations in soils. Calculated BCF and TF values showed that soils characteristics and air deposition affect uranium absorption and that different uranium species have different affinities to U. dioica plants. The values of (234)U/(238)U activity ratio indicate natural origin of these radioisotopes in analyzed plants. Uranium concentration in plants roots is negatively weakly correlated with distance from phosphogypsum stockpile.

  17. Carcinogenesis of Depleted Uranium Fragments.

    Science.gov (United States)

    1996-02-01

    P. W. Morrow, B. J. Panner and R. B. Baggs (eds.): Nephrotoxicity of Uranyl Fluoride and Reversibility of Renal Injury in the Rat. NUREG /CR-4951...Accidental Exposure to Uranium Hexafluoride. NUREG /CR-5566, PNL-7328, Prepared for U.S. Nuclear Regulatory Commission, Washington, DC, 1990. Foulkes, E. C...Hydrolysis Products of Uranium Hexafluoride, NUREG /CR-2268, RH, Prepared for Division of Health Siting and Waste Management, Washington, DC, 1982. 20 Nothdurft

  18. DESIGN STUDY FOR A LOW-ENRICHED URANIUM CORE FOR THE HIGH FLUX ISOTOPE REACTOR, ANNUAL REPORT FOR FY 2010

    Energy Technology Data Exchange (ETDEWEB)

    Cook, David Howard [ORNL; Freels, James D [ORNL; Ilas, Germina [ORNL; Jolly, Brian C [ORNL; Miller, James Henry [ORNL; Primm, Trent [ORNL; Renfro, David G [ORNL; Sease, John D [ORNL; Pinkston, Daniel [ORNL

    2011-02-01

    This report documents progress made during FY 2010 in studies of converting the High Flux Isotope Reactor (HFIR) from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. With axial and radial grading of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in performance to users from the current level. Studies are reported of support to a thermal hydraulic test loop design, the implementation of finite element, thermal hydraulic analysis capability, and infrastructure tasks at HFIR to upgrade the facility for operation at 100 MW. A discussion of difficulties with preparing a fuel specification for the uranium-molybdenum alloy is provided. Continuing development in the definition of the fuel fabrication process is described.

  19. Potential of Melastoma malabathricum as bio-accumulator for uranium and thorium from soil

    Energy Technology Data Exchange (ETDEWEB)

    Saat, Ahmad, E-mail: ahmad183@salam.uitm.edu.my [Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Kamsani, Ain Shaqina; Kamri, Wan Nur Aina Nadzira; Talib, Nur Hasyimah Mat; Wood, Ab Khalik; Hamzah, Zaini [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia)

    2015-04-29

    Uranium and Thorium are naturally occuring radionuclides. However, due to anthropogenic activities in some locations their concentrations in the soils could be elevated. This study explores the potential of Melastoma malabathricum (locally known as ‘pokok senduduk’) as bio-accumulator of uranium and thorium from soils of three different study areas, namely former tin mining, industrial and residential/commercial areas in Peninsular Malaysia. The study found elevated concentrations of uranium and thorium in former tin mining soils as compared to natural abundance. However in industral and residential/commercial areas the concentrations are within the range of natural abundance. In terms of transfer factor (TF), in ex-mining areas TF > 1 for uranium in the leaf, stem and roots, indicating accumulation of uranium from soil. However for thorium TF < 1, indicating the occurence of transfer from soil to root, stem and leaf, but no accumulation. For other areas only transfer of uranium and thorium were observed. The results indicated the potential of Melastoma malabathricum to be used as bio-accumulatior of uranium, especially in areas of elevated concentration.

  20. Conversational Telugu.

    Science.gov (United States)

    Beinstein, Judith; And Others

    The purpose of this text is to develop elementary conversational skills in Telugu. The language materials consist of four types of language learning activities. The first, and most predominant, is the unit microwave cycle. These cycles divide the learning process into two basic phases, the first of which involves mimicry, memorization, and…

  1. Conversion Disorder

    National Research Council Canada - National Science Library

    Fisher, Robert S; Stonnington, Cynthia M; Barry, John J

    2006-01-01

    ... to proceed after establishing a diagnosis of conversion disorder. Case Presentation "Ms. A," a 53-year-old left-handed woman, was admitted to our epilepsy monitoring unit for evaluation of a 4-month history of tremors, head bobbing, and episodic loss of awareness. The onset of these symptoms was 1 week after she had visited an emergency department...

  2. Controlled synthesis of thorium and uranium oxide nanocrystals.

    Science.gov (United States)

    Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Gouder, Thomas; Courtois, Eglantine; Kübel, Christian; Meyer, Daniel

    2013-04-22

    Very little is known about the size and shape effects on the properties of actinide compounds. As a consequence, the controlled synthesis of well-defined actinide-based nanocrystals constitutes a fundamental step before studying their corresponding properties. In this paper, we report on the non-aqueous surfactant-assisted synthesis of thorium and uranium oxide nanocrystals. The final characteristics of thorium and uranium oxide nanocrystals can be easily tuned by controlling a few experimental parameters such as the nature of the actinide precursor and the composition of the organic system (e.g., the chemical nature of the surfactants and their relative concentrations). Additionally, the influence of these parameters on the outcome of the synthesis is highly dependent on the nature of the actinide element (thorium versus uranium). By using optimised experimental conditions, monodisperse isotropic uranium oxide nanocrystals with different sizes (4.5 and 10.7 nm) as well as branched nanocrystals (overall size ca. 5 nm), nanodots (ca. 4 nm) and nanorods (with ultra-small diameters of 1 nm) of thorium oxide were synthesised.

  3. Uranium mining operations in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Rios, J.-M.; Arnaiz, J.; Criado, M.; Lopez, A.

    1995-12-31

    The Empresa Nacional del Uranio, SA (ENUSA) was founded in 1972 to undertake and develop the industrial and procurement activities of the nuclear fuel cycle in Spain. Within the organisation of ENUSA, the Uranium Division is directly responsible for the uranium mining and production operations that have been carried out since 1973 in the area of Ciudad Rodrigo in the province of Salamanca. These activities are based on open pit mining, heap leaching and a hydrometallurgical plant (Elefante) for extracting uranium concentrates from the ore. This plant was shut down in 1993 and a new plant was started up on the same site (Quercus) with a dynamic leaching process. The nominal capacity of the new plant is 950 t U{sub 3}O{sub 8} per year. Because of the historically low uranium prices which have recently prevailed, the plant is currently running at a strategic production rate of 300 t U{sub 3}O{sub 8} per year. From 1981 to 1990, in the area of La Haba (Badajoz province), ENUSA also operated a uranium production site, based on open pit mining, and an experimental extraction plant (Lobo-G). ENUSA is currently decommissioning these installations. This paper describes innovations and improvements that ENUSA has recently introduced in the field of uranium concentrates production with a view to cutting production costs, and to improving the decommissioning and site restoration processes in those sites where production is being shut down or resources have been worked out. (author).

  4. The chemical industry of uranium in France; L'industrie chimique de l'uranium en France

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, B. [Commissariat a l' Energie Atomique, Paris (France). Centre d' Etudes Nucleaires

    1955-07-01

    The actual CEA program is concerned with the construction of two large graphite reactors, each of those containing at least one hundred tons of uranium metal with nuclear purity. The uranium for these two reactors will be regularly supplied by new resources discovered in France and Madagascar in the last five years. The working and treatment of such ore have led to the creation of an important french industry of which the general outline and principle are described. The operated ores have got different natures and concentration, individual characteristics are described for the main ores.The most high-grade ore are transported to a central plant in Bouchet near Paris; the low-grade ore are concentrated by physical methods or chemical processes of which principles and economy are studied with constancy. The acid processes are the only used until now, although the carbonated alkaline processes has been studied in France. The next following steps after the acid p