Simulation of uranium and plutonium oxides compounds obtained in plasma

Science.gov (United States)

Novoselov, Ivan Yu.; Karengin, Alexander G.; Babaev, Renat G.

2018-03-01

The aim of this paper is to carry out thermodynamic simulation of mixed plutonium and uranium oxides compounds obtained after plasma treatment of plutonium and uranium nitrates and to determine optimal water-salt-organic mixture composition as well as conditions for their plasma treatment (temperature, air mass fraction). Authors conclude that it needs to complete the treatment of nitric solutions in form of water-salt-organic mixtures to guarantee energy saving obtainment of oxide compounds for mixed-oxide fuel and explain the choice of chemical composition of water-salt-organic mixture. It has been confirmed that temperature of 1200 °C is optimal to practice the process. Authors have demonstrated that condensed products after plasma treatment of water-salt-organic mixture contains targeted products (uranium and plutonium oxides) and gaseous products are environmental friendly. In conclusion basic operational modes for practicing the process are showed.

Redox behaviour of uranium with iron compounds

International Nuclear Information System (INIS)

Ithurbide, A.

2009-10-01

An option investigated for the management of long-term nuclear waste is a repository in deep geological formations. It is generally admitted that the release of radionuclides from the spent fuel in the geosphere could occur several thousand years after the beginning of the storage. Therefore, to assess the safety of the long-term disposal, it is important to consider the phenomena that can reduce the migration, and in particular the migration of uranium. The aim of this work is to study if siderite, an iron compound present both in the near - and far -field, can limit this migration as well as the role played by the redox process. Siderite thin layers have been obtained by electrochemistry. The layers are adherent and homogeneous. Their thickness is about 1 μm and they are composed of spherical grains. Analytical characterizations performed show that siderite is free of any impurity and does not exhibit any trace of oxidation. The interactions between siderite and uranium (VI) have been carried out in solutions considered as representative of environmental waters, in terms of pH and carbonate concentration. The retention of uranium on the thin layer is important since, after 24 hours of interaction, it corresponds to retention capacities of several hundreds of uranium micro-moles per gram of siderite. XPS analysis show that, in any studied condition, part of uranium present on the thin layer is reduced into an over stoichiometric uranium dioxide. The process of interaction differs depending on the considered environment, specially on the stability of siderite. (author)

Study of the interactions between uranium and organic compounds in the hydrothermal systems

International Nuclear Information System (INIS)

Salze, David

2008-01-01

Formers studies on the relations between organic matter and uranium have shown that these interactions go since the complexation and the transport of uranium in organics fluids until its reduction by the organic matter leading to the uranium-bearing mineral precipitation. An experimental study of these reactions to 200 deg. C and 500 bars between experimental compounds (pure organic compounds) such as the n-alkanes (n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, n-tetradecane and n-hexadecane), an n-alkene hydrocarbon (n-dec-1-ene), cycles (butyl-cyclohexane and cyclo-hexane) and the aromatic ones (butyl-benzene and naphthalene), and hexavalent uranium oxides was undertaken. These experiments allowed to show a progressive oxidation of n-alkanes starting from made up C6. The increasing size of the aliphatic chains and the increase in the time of setting in interaction are major factors of the increase in the environment oxidizing capacity in interaction with uranium on the organic compound. The determination of the oxidation step of uranium oxides after experiment made it possible to determine that in aqueous environment the aliphatic model compounds are reducers more powerful than the aromatic compounds. An organic matter from lake or marine origin generally has an aliphatic fraction larger than the organic matter of continental origin and thus will be more likely to reduce uranium. A natural example, the uranium deposits in the sandstones from Arlit, the tectono-lithologic type, was selected in order to apply the results obtained in the experimental part. They are located in fluviatile sandstones rich in organic matter of continental origin (type III) deposited in the paleo-channels. Former authors considered that only this organic matter of type III was responsible for the reduction of U (VI) in U (IV). Work which was undertaken in the present study shows that migrated oils of probable marine origin strongly contributed to the genesis

Uranium magnetism in UGa2 and U(Gasub(1-x)Alsub(x))2 compounds

International Nuclear Information System (INIS)

Ballou, R.

1983-01-01

Magnetism of intermetallic compounds of uranium is studied. A monocrystal of the highly anisotropic ferromagnetic material UGa 2 is studied by polarized neutron diffraction. Localisation of 5f electrons is evidenced. Magnetic structure of uranium in UGa 2 is determined. The pseudobinary compound U(Gasub(1-x)Alsub(x)) 2 is studied for crystal structure, ferromagnetism, paramagnetism, specific heat and resistivity [fr

Thermogravimetric control of intermediate compounds in uranium metallurgy; Control termogravimetrico de productos intermedios de la metalurgia del uranio

Energy Technology Data Exchange (ETDEWEB)

Gasco Sanchez, L; Fernandez Cellini, R

1959-07-01

The thermal decomposition of some intermediate compounds in the metallurgy of the uranium as uranium peroxide, ammonium uranate, uranium and ammonium penta-fluoride, uranium tetrafluoride and uranous oxide has been study by means of the Chevenard's thermo balance. Some data on pyrolysis of synthetic mixtures of intermediate compounds which may occasionally appear during the industrial process, are given. Thermogravimetric methods of control are suggested, usable in interesting products in the uranium metallurgy. (Author) 20 refs.

Methodology for uranium compounds characterization applied to biomedical monitoring

International Nuclear Information System (INIS)

Ansoborlo, E.; Chalabreysse, J.; Henge-Napoli, M.H.; Pujol, E.

1991-01-01

Chronic exposure and accidental contamination to uranium compounds in the nuclear industry, led the authors to develop a methodology in order to characterize those compounds applied to biomedical monitoring. Such a methodology, based on the recommendation of the ICRP and the assessment of Annual Limit on Intake (ALI) values, involves two main steps: (1) The characterization of the industrial compound, i.e. its physico-chemical properties like density (g cm -3 ), specific area (m 2 g -1 ), x-ray spectrum (crystalline form), solid infrared spectrum (wavelength and bounds), mass spectrometry (isotopic composition), and particle size distribution including measurement of the Activity Median Aerodynamic Diameter (AMAD). They'll specially study aging and hydration state of some compounds. (2) The study of in vitro solubility in several biochemical medium like bicarbonates, Basal Medium Eagle (BME) used in cellular culture, Gamble solvent, which is a serum simulant, with oxygen bubbling, and Gamble added with superoxide anions O2 - . Those different mediums allow one to understand the dissolution mechanisms (oxidation, chelating effects...) and to give ICRP classification D, W, or Y. Those two steps are essential to assess a biomedical monitoring either in routine or accidental exposure, and to calculate the ALI. Results on UO3, UF4 and U02 in the French uranium industry are given

Thermogravimetric control of intermediate compounds in uranium metallurgy; Control termogravimetrico de productos intermedios de la metalurgia del uranio

Energy Technology Data Exchange (ETDEWEB)

Gasco Sanchez, L.; Fernandez Cellini, R.

1959-07-01

The thermal decomposition of some intermediate compounds in the metallurgy of the uranium as uranium peroxide, ammonium uranate, uranium and ammonium penta-fluoride, uranium tetrafluoride and uranous oxide has been study by means of the Chevenard's thermo balance. Some data on pyrolysis of synthetic mixtures of intermediate compounds which may occasionally appear during the industrial process, are given. Thermogravimetric methods of control are suggested, usable in interesting products in the uranium metallurgy. (Author) 20 refs.

Determination of chlorine in nuclear-grade uranium compounds by ion-selective electrode

International Nuclear Information System (INIS)

Yang Chunqing; Liu Fuyun; Huang Dianfan.

1989-01-01

The determination of microamount chlorine in nuclear-grade uranium compounds is described. Chlorine is separated from uranium oxide pyrohydrolytically with stream of wet oxygen in a furnace at 800-900 deg C. Chlorine is volatilized as hydrochloric acid, which then is absorbed in a dilute alkaline solution and measured with chlorine selective electrode. This method covers the concentration range of 10-500 ppm chlorine in uranium oxide. The relative standard diviation is better than 10% and recovery of 85-108% has been reported

Determination of oxygen in uranium compounds using sulfur monochloride

International Nuclear Information System (INIS)

Baudin, G.; Besson, J.; Blum, P.L.; Tran-Van, Danh

1964-01-01

The authors have described in an other paper (Anal. Chim. Acta, in press) a method for oxygen determination in uranium compounds, in which the sample is attacked by sulfur monochloride. The present paper is concerned with the experimental aspects of the method: apparatus procedure. (authors) [fr

Method of removing uranium and its compounds from mine wastewaters and from aqueous solutions discharged in hydrometallurgical uranium ore treatment

International Nuclear Information System (INIS)

Jilek, R.; Prochazka, H.; Kuhr, I.; Fuska, J.; Nemec, P.; Katzer, J.

1974-01-01

The separation of uranium and its compounds from mine wastewaters and from water solutions discharged from uranium ore hydrometallurgical treatment, and its eventual simultaneous concentration in the biomass during uranium ore technological processing are described. The solutions are replenished with nutrients necessary for the growth of microorganisms, mainly with nitrogen, carbon and phosphorus and inoculated with fungi. During submersion cultivation, uranium incorporates in the mycelium, or is bound physico-chemically to the mycelium components. Together with these components, uranium is mechanically separated, i.e., by filtration, centrifugation or sedimentation. Organisms of the Fungi imperfecti class, mainly the Aspergillus and Penicillium genera are used for cultivation which may be continuous or semicontinuous. (B.S.)

Feasibility study of the dissolution rates of uranium ore dust, uranium concentrates and uranium compounds in simulated lung fluid

International Nuclear Information System (INIS)

Robertson, R.

1986-01-01

A flow-through apparatus has been devised to study the dissolution in simulated lung fluid of aerosol materials associated with the Canadian uranium industry. The apparatus has been experimentally applied over 16 day extraction periods to approximately 2g samples of < 38um and 53-75um particle-size fractions of both Elliot Lake and Mid-Western uranium ores. The extraction of uranium-238 was in the range 24-60% for these samples. The corresponding range for radium-226 was 8-26%. Thorium-230, lead-210, polonium-210, and thorium-232 were not significantly extracted. It was incidentally found that the elemental composition of the ores studied varies significantly with particle size, the radionuclide-containing minerals and several extractable stable elements being concentrated in the smaller size fraction. Samples of the refined compounds uranium dioxide and uranium trioxide were submitted to similar 16 day extraction experiments. Approximately 0.5% of the uranium was extracted from a 0.258g sample of unsintered (fluid bed) uranium dioxide of particle size < 38um. The corresponding figure for a 0.292g sample of uranium trioxide was 97%. Two aerosol samples on filters were also studied. Of the 88ug uranium initially measured on stage 2 of a cascade impactor sample collected from the yellow cake packing area of an Elliot Lake mill, essentially 100% was extracted over a 16 day period. The corresponding figure for an open face filter sample collected in a fuel fabrication plant and initially measured at 288ug uranium was approximately 3%. Recommendations are made with regard to further work of a research nature which would be useful in this area. Recommendations are also made on sampling methods, analytical methods and extraction conditions for various aerosols of interest which are to be studied in a work of broader scope designed to yield meaningful data in connection with lung dosimetry calculations

Polynuclear compounds of uranium: structure, reactivity and properties

International Nuclear Information System (INIS)

Mougel, V.

2012-01-01

The study and comprehension of actinide's fundamental chemistry have important implications both for the development of new nuclear fuel and for the nuclear fuel reprocessing. One of the major issues in these processes is the ease of uranium to undergo redox reactions and to form polynuclear assemblies, which largely perturb these processes. However, despite their relevance, only few synthetic routes towards polynuclear uranium assemblies are described in the literature, and most of the polynuclear complexes reported are formed by serendipity rather than by rational design. Moreover, polynuclear uranium compounds are highly promising for the design of magnetic materials with improved properties and for reactivity studies. The aim of this work is the synthesis of polynuclear uranium complexes and the study of their reactivity and coordination properties. New synthetic routes to uranium polynuclear assemblies were developed and the study of their physico-chemical properties was carried out. The first approach investigated was based on pentavalent uranyl chemistry. Uranyl(V) is known to form aggregates via an interaction between uranyl moieties often named cation-cation interaction, but the isolation of uranyl(V) complexes had been largely limited by its ease of disproportionation. We isolated the first stable uranyl(V) polynuclear assembly using Salen-type Schiff base ligand. Based on this result, a fine tuning of the ligand and counter-ion properties resulted in the isolation of a large family of uranyl(V) polynuclear assemblies and in a better understanding of the parameters ruling their stability. Moreover, rare examples of clear antiferromagnetic couplings were observed with these complexes. In addition, this synthetic path was used to build the first 5f-3d cluster presenting single molecule magnet properties. The second approach used in this thesis consisted in the synthesis of oxo/hydroxo uranium clusters. The controlled hydrolysis of trivalent uranium in

The contribution of radioisotopes in secular equilibrium in the transport index of fissile uranium compounds in different enrichments

International Nuclear Information System (INIS)

Silva, Teresinha de Moraes da; Sordi, Gian M.A.A.

2008-01-01

Full text: This work shows the contribution of radioisotopes in secular equilibrium in the transport index (TI) of some fissile uranium compounds: uranium oxides UO 2 , U 3 O 8 and uranium silicide U 3 Si 2 , taking into account the different enrichment grades.The range of enrichment (E%) studied was 3,4,5,7,10,20,30,40,50,93 and 100. Initially, the cell of optimum moderation ratio was built, since it represents the most reactive of the system (consisting of uranium), with maximum infinitive multiplication factor k∞, in certain concentration of uranium for each enrichment. This was made using the computer program Gamtec II. The critical radius of a sphere was calculated for a cell of optimum moderation ratio, in order to calculate the critical mass of the uranium compound or of the uranium element for each specific enrichment. For this the program Citation was used. In this study it was calculated the smallest critical mass of the uranium compound or the smallest critical mass of the uranium element. The objective was to match the largest mass of the uranium with each specific enrichment. The largest safety mass corresponds to 45% the critical mass the compound uranium or uranium element. Then, we calculated the uranium element safety mass, which it related to a fifth of this mass to the value 50, which corresponds to criticality safety index (CSI). That is, 20% of the safety mass is the value where the transport is carried out with subcritical mass, going in favor of the security. From the uranium element safety mass (USM) was determined for each enrichment , and it was calculated the mass of 235 U, activity 235 U and dose rate of 235 U, the same items were calculated for the isotope 238 U. The total dose rate was calculated for two isotopes, and applying the transport index definition as the gamma dose rate for the distance of 1 m from the packed, it was determined the TI for 20% of the safety mass for each enrichment of the compound studied. The study of

Flame photometric determination of Na, K and Li in uranium compounds

International Nuclear Information System (INIS)

Sabato, S.F.; Lordello, A.R.

1985-01-01

A flame photometric method for the determination of Na, K and Li in uranium compounds is described. The uranium is separated by solvent extraction from hydrochloric acid medium with tri-butyl phosphate. Amounts of uranium in order of 20 μg/ml don't cause any interference in the photometric results. The element Na presents a residual concentration due to the contamination of the reagents. The relative standard deviation is about 10% for the three elements. The relative error varies with the concentration of the element and it is between 1 and 24% for Na, between O and 12% for K and between O and 33% for Li. (Author) [pt

Water Solubility of Plutonium and Uranium Compounds and Residues at TA-55

International Nuclear Information System (INIS)

Reilly, Sean Douglas; Smith, Paul Herrick; Jarvinen, Gordon D.; Prochnow, David Adrian; Schulte, Louis D.; DeBurgomaster, Paul Christopher; Fife, Keith William; Rubin, Jim; Worl, Laura Ann

2016-01-01

Understanding the water solubility of plutonium and uranium compounds and residues at TA-55 is necessary to provide a technical basis for appropriate criticality safety, safety basis and accountability controls. Individual compound solubility was determined using published solubility data and solution thermodynamic modeling. Residue solubility was estimated using a combination of published technical reports and process knowledge of constituent compounds. The scope of materials considered includes all compounds and residues at TA-55 as of March 2016 that contain Pu-239 or U-235 where any single item in the facility has more than 500 g of nuclear material. This analysis indicates that the following materials are not appreciably soluble in water: plutonium dioxide (IDC=C21), plutonium phosphate (IDC=C66), plutonium tetrafluoride (IDC=C80), plutonium filter residue (IDC=R26), plutonium hydroxide precipitate (IDC=R41), plutonium DOR salt (IDC=R42), plutonium incinerator ash (IDC=R47), uranium carbide (IDC=C13), uranium dioxide (IDC=C21), U 3 O 8 (IDC=C88), and uranium filter residue (IDC=R26). This analysis also indicates that the following materials are soluble in water: plutonium chloride (IDC=C19) and uranium nitrate (IDC=C52). Equilibrium calculations suggest that PuOCl is water soluble under certain conditions, but some plutonium processing reports indicate that it is insoluble when present in electrorefining residues (R65). Plutonium molten salt extraction residues (IDC=R83) contain significant quantities of PuCl 3 , and are expected to be soluble in water. The solubility of the following plutonium residues is indeterminate due to conflicting reports, insufficient process knowledge or process-dependent composition: calcium salt (IDC=R09), electrorefining salt (IDC=R65), salt (IDC=R71), silica (IDC=R73) and sweepings/screenings (IDC=R78). Solution thermodynamic modeling also indicates that fire suppression water buffered with a commercially-available phosphate

Water Solubility of Plutonium and Uranium Compounds and Residues at TA-55

Energy Technology Data Exchange (ETDEWEB)

Reilly, Sean Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Smith, Paul Herrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Jarvinen, Gordon D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Prochnow, David Adrian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Schulte, Louis D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; DeBurgomaster, Paul Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Fife, Keith William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Rubin, Jim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States

2016-06-13

Understanding the water solubility of plutonium and uranium compounds and residues at TA-55 is necessary to provide a technical basis for appropriate criticality safety, safety basis and accountability controls. Individual compound solubility was determined using published solubility data and solution thermodynamic modeling. Residue solubility was estimated using a combination of published technical reports and process knowledge of constituent compounds. The scope of materials considered includes all compounds and residues at TA-55 as of March 2016 that contain Pu-239 or U-235 where any single item in the facility has more than 500 g of nuclear material. This analysis indicates that the following materials are not appreciably soluble in water: plutonium dioxide (IDC=C21), plutonium phosphate (IDC=C66), plutonium tetrafluoride (IDC=C80), plutonium filter residue (IDC=R26), plutonium hydroxide precipitate (IDC=R41), plutonium DOR salt (IDC=R42), plutonium incinerator ash (IDC=R47), uranium carbide (IDC=C13), uranium dioxide (IDC=C21), U₃O₈ (IDC=C88), and uranium filter residue (IDC=R26). This analysis also indicates that the following materials are soluble in water: plutonium chloride (IDC=C19) and uranium nitrate (IDC=C52). Equilibrium calculations suggest that PuOCl is water soluble under certain conditions, but some plutonium processing reports indicate that it is insoluble when present in electrorefining residues (R65). Plutonium molten salt extraction residues (IDC=R83) contain significant quantities of PuCl₃, and are expected to be soluble in water. The solubility of the following plutonium residues is indeterminate due to conflicting reports, insufficient process knowledge or process-dependent composition: calcium salt (IDC=R09), electrorefining salt (IDC=R65), salt (IDC=R71), silica (IDC=R73) and sweepings/screenings (IDC=R78). Solution thermodynamic modeling also indicates that fire suppression water buffered with a

Separation of chloride and fluoride from uranium compounds and their determination by ion selective electrodes

International Nuclear Information System (INIS)

Pires, M.A.F.; Abrao, A.

1982-01-01

Fluoride and chloride must be rigorously controlled in uranium compounds, especially in ceramic grade UO 2 . Their determination is very difficult without previous uranium separation, particularly when both are at a low concentration. A simple procedure is described for this separation using a strong cationic resin to retain the uranyl ion. Both anions are determined in the effluent solution. Uranium compounds of nuclear fuel cycle, especially ammonium diuranate, ammonium uranyl tricarbonate, sodium diuranate, uranium trioxide and dioxide and uranium peroxide are dissolved in nitric acid and the solutions are percolated through the resin column. Chloride and fluoride are determined in the effluent by selective electrodes, the detection limits being 0.02 μg F - /ml and 1.0 μg Cl - /ml. The dissolution of the sample, the acidity of the solution, the measurement conditions and the sensitivity of the method are discussed. (Author) [pt

Martingalas discretas. Aplicaciones

Directory of Open Access Journals (Sweden)

Miguel A. Marmolejo

2009-12-01

Full Text Available Debido a su amplio rango de aplicaciones, la teoría de las martingalas es parte fundamental de la probabilidad. En este artículo se presentan las nociones básicas de las martingalas discretas y se recopilan algunas de sus aplicaciones en probabilidad y análisis, dando idea de los diferentes contextos donde se usan.

Reaction of Tris(cyclopentadienyl)uranium compounds with amines, azides, and related ligands

International Nuclear Information System (INIS)

Rosen, R.K.

1989-12-01

The trivalent uranium compound, (MeC 5 H 4 ) 3 U(thf), serves as a one- or two-electron reducing agent towards azides, RN 3 . These reactions produce either the uranium(IV) azide, (MeC 5 H 4 ) 3 UN 3 , or uranium(V) imides, (MeC 5 H 4 ) 3 UNR. The role of steric and electronic effects upon this reaction has been investigated using several series of azides. For Me 3 XN 3 , the imides are produced when X = C or Si, both products are formed when X = Ge, and the azide is produced when X = Sn. For Ph 3 XN 3 , the azide is produced when X = C or Sn. For Ph 3-x CH 3 N 3 , the imide is produced when x = 2 and both compounds are produced when x = 1. For substituted phenylazides, RC 6 H 4 N 3 , only the imides are produced. The magnetic properties of uranium diimides, [(MeC 5 H 4 ) 3 U] 2 (μ-NRN), were investigated. Several uranium(III) amines, (MeC 5 H 4 ) 3 U(NH 2 R), were produced from (MeC 5 H 4 ) 3 U(thf) and RNH 2 , and NH 3 was found to be a better ligand towards (MeC 5 H 4 ) 3 U than is PMe 3

Semi-automatic version of the potentiometric titration method for characterization of uranium compounds.

Science.gov (United States)

Cristiano, Bárbara F G; Delgado, José Ubiratan; da Silva, José Wanderley S; de Barros, Pedro D; de Araújo, Radier M S; Dias, Fábio C; Lopes, Ricardo T

2012-09-01

The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. Copyright © 2012 Elsevier Ltd. All rights reserved.

No fluorinated compounds in the uranium conversion process: risk analysis and proposition of pictograms

International Nuclear Information System (INIS)

Jeronimo, Adroaldo Clovis; Oliveira, Wagner dos Santos

2012-01-01

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)

Carbon determination in uranium and its compounds

International Nuclear Information System (INIS)

Silva Queiroz, C.A. da; Abrao, A.

1982-01-01

Carbon content in uranium and its compounds, especially ceramic grade UO 2 , must be controlled rigorously. A method for the determination of carbon with the aid of commercial equipment which uses platinum as a catalyst for the oxidation of CO, and infrared cells for CO 2 measurement is described. The detection limit is 5μg C/g U and the determination range is 0.0005 to 5% C/U. The method is being used routinely to control the carbon content in nuclear fuel materials. (Author) [pt

Study of internal exposure to uranium compounds in fuel fabrication plants in Brazil

International Nuclear Information System (INIS)

Santos, Maristela Souza

2006-01-01

The International Commission on Radiological Protection (ICRP) Publication 66 and Supporting Guidance 3) strongly recommends that specific information on lung retention parameters should be used in preference to default values wherever appropriate, for the derivation of effective doses and for bioassay interpretation of monitoring data. A group of 81 workers exposed to UO 2 at the fuel fabrication facility in Brazil was selected to evaluate the committed effective dose. The workers were monitored for determination of uranium content in the urinary and faecal excretion. The contribution of intakes by ingestion and inhalation were assessed on the basis of the ratios of urinary to fecal excretion. For the selected workers it was concluded that inhalation dominated intake. According to ICRP 66, uranium oxide is classified as insoluble Type S compound. The ICRP Supporting Guidance 3 and some recent studies have recommended specific lung retention parameters to UO 2 . The solubility parameters of the uranium oxide compound handled by the workers at the fuel fabrication facility in Brazil was evaluated on the basis of the ratios of urinary to fecal excretion. Excretion data were corrected for dietary intakes. This paper will discuss the application of lung retention parameters recommended by the ICRP models to these data and also the dependence of the effective committed dose on the lung retention parameters. It will also discuss the problems in the interpretation of monitoring results, when the worker is exposed to several uranium compounds of different solubilities. (author)

Overview of toxicity data and risk assessment methods for evaluating the chemical effects of depleted uranium compounds

International Nuclear Information System (INIS)

Hartmann, H.M.; Monette, F.A.; Avci, H.I.

2000-01-01

In the United States, depleted uranium is handled or used in several chemical forms by both governmental agencies and private industry (primarily companies producing and machining depleted uranium metal for military applications). Human exposure can occur as a result of handling these compounds, routine low-level effluent releases to the environment from processing facilities, or materials being accidentally released from storage locations or during processing or transportation. Exposure to uranium can result in both chemical and radiological toxicity, but in most instances chemical toxicity is of greater concern. This article discusses the chemical toxic effects from human exposure to depleted uranium compounds that are likely to be handled during the long-term management and use of depleted uranium hexafluoride (UF 6 ) inventories in the United States. It also reviews representative publications in the toxicological literature to establish appropriate reference values for risk assessments. Methods are described for evaluating chemical toxicity caused by chronic low-level exposure and acute exposure. Example risk evaluations are provided for illustration. Preliminary results indicate that chemical effects of chronic exposure to uranium compounds under normal operating conditions would be negligibly small. Results also show that acute exposures under certain accident conditions could cause adverse chemical effects among the populations exposed.

Photon attenuation properties of some thorium, uranium and plutonium compounds

Energy Technology Data Exchange (ETDEWEB)

Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

Mass attenuation coefficients, effective atomic numbers, effective electron densities for nuclear materials; thorium, uranium and plutonium compounds have been studied. The photon attenuation properties for the compounds have been investigated for partial photon interaction processes by photoelectric effect, Compton scattering and pair production. The values of these parameters have been found to change with photon energy and interaction process. The variations of mass attenuation coefficients, effective atomic number and electron density with energy are shown graphically. Moreover, results have shown that these compounds are better shielding and suggesting smaller dimensions. The study would be useful for applications of these materials for gamma ray shielding requirement. (Author)

Compound Nucleus Reactions in LENR, Analogy to Uranium Fission

Science.gov (United States)

Hora, Heinrich; Miley, George; Philberth, Karl

2008-03-01

The discovery of nuclear fission by Hahn and Strassmann was based on a very rare microanalytical result that could not initially indicate the very complicated details of this most important process. A similarity is discussed for the low energy nuclear reactions (LENRs) with analogies to the yield structure found in measurements of uranium fission. The LENR product distribution measured earlier in a reproducible way in experiments with thin film electrodes and a high density deuteron concentration in palladium has several striking similarities with the uranium fission fragment yield curve.ootnotetextG.H. Miley and J.A. Patterson, J. New Energy 1, 11 (1996); G.H. Miley et al, Proc ICCF6, p. 629 (1997).This comparison is specifically focussed to the Maruhn-Greiner local maximum of the distribution within the large-scale minimum when the fission nuclei are excited. Implications for uranium fission are discussed in comparison with LENR relative to the identification of fission a hypothetical compound nuclear reaction via a element ^306X126 with double magic numbers.

Reaction of Tris(cyclopentadienyl)uranium compounds with amines, azides, and related ligands

Energy Technology Data Exchange (ETDEWEB)

Rosen, R.K.

1989-12-01

The trivalent uranium compound, (MeC{sub 5}H{sub 4}){sub 3}U(thf), serves as a one- or two-electron reducing agent towards azides, RN{sub 3}. These reactions produce either the uranium(IV) azide, (MeC{sub 5}H{sub 4}){sub 3}UN{sub 3}, or uranium(V) imides, (MeC{sub 5}H{sub 4}){sub 3}UNR. The role of steric and electronic effects upon this reaction has been investigated using several series of azides. For Me{sub 3}XN{sub 3}, the imides are produced when X = C or Si, both products are formed when X = Ge, and the azide is produced when X = Sn. For Ph{sub 3}XN{sub 3}, the azide is produced when X = C or Sn. For Ph{sub 3-x}CH{sub 3}N{sub 3}, the imide is produced when x = 2 and both compounds are produced when x = 1. For substituted phenylazides, RC{sub 6}H{sub 4}N{sub 3}, only the imides are produced. The magnetic properties of uranium diimides, ((MeC{sub 5}H{sub 4}){sub 3}U){sub 2}({mu}-NRN), were investigated. Several uranium(III) amines, (MeC{sub 5}H{sub 4}){sub 3}U(NH{sub 2}R), were produced from (MeC{sub 5}H{sub 4}){sub 3}U(thf) and RNH{sub 2}, and NH{sub 3} was found to be a better ligand towards (MeC{sub 5}H{sub 4}){sub 3}U than is PMe{sub 3}.

A gravimetric method for the determination of oxygen in uranium oxides and ternary uranium oxides by addition of alkaline earth compounds

International Nuclear Information System (INIS)

Fujino, Takeo; Tagawa, Hiroaki; Adachi, Takeo; Hashitani, Hiroshi

1978-01-01

A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800-1100 0 C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UOsub(2+x) test sample is +-0.0008-0.001, if a correction is applied for atmospheric moisture absorbed during mixing. (Auth.)

Molecular dynamics simulation of uranium compound adsorption on solid surface

International Nuclear Information System (INIS)

Omori, Yuki; Takizawa, Yuji; Okamoto, Tsuyoshi

2010-01-01

Particles mixed in the UF6 gas have the property of accumulating on the inside of piping or units. This type of accumulation will cause material unaccounted for (MUF) in the UF6 gas processing facilities. Development of a calculation model for estimating the accumulation rate of uranium compounds has been expected. And predicting possible part of the units where uranium compounds adsorb will contribute to design an effective detection system. The purpose of this study is to take the basic knowledge of the particle's adsorption mechanism from the microscopic point of view. In simulation analysis, UF5 model particle is produced, then two types of solid surfaces are prepared; one is a solid surface at rest and the other is a moving solid surface. The result obtained by the code 'PABS' showed that when the solid surface moves at a lower velocity, the particle's adsorption process dominates over the particle's breakup one. Besides the velocity of the solid surface, other principal factors affecting an adsorption ratio were also discussed. (author)

Synthesis and studies of some organometallic compounds of uranium IV

International Nuclear Information System (INIS)

Marquet-Ellis, Hubert; Folcher, Gerard.

1975-06-01

The organometallic compounds of uranium IV have been well known for a long-time but some difficulties in the synthese subsist. The procedures and the apparatus allowing to obtain these compounds with good yields are described. The cyclopenta dienyl compounds U(C 5 H 5 ) 3 Cl, U(C 5 H 5 ) 4 are prepared by reaction of UCl 4 with Na(C 5 H 5 ) in tetrahydrofurane. The cyclooctatetraene compound U(C 8 H 8 ) 2 ''Uranocene'' is obtained by reaction of K 2 (C 8 H 8 ) on UCl 4 in tetrahydrofurane. The NMR spectrum of the solution during the reaction shows the appearance of the product. These compounds have been identified by chemical analysis and X rays. The visible spectra of U(C 5 H 5 ) 2 Cl and U(C 8 H 8 ) 2 in gaseous phase have been obtained [fr

Uranium conversion

International Nuclear Information System (INIS)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

2006-03-01

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 6 and UF 4 are present require equipment that is made of corrosion resistant material

Coordination compounds of titanium, zirconium, tin, thorium and uranium

International Nuclear Information System (INIS)

Deshpande, S.G.; Jain, S.C.

1990-01-01

Reactions of isatin, furoic acid and picolinic acid have been carried out with titanium tetrachloride, tin tetrachloride, thorium tetrachloride, zirconyl chloride and uranyl nitrate. While 2:3(metal:ligand) type compounds of isatin have been obtained with Ti(IV) and Sn(IV), zirconium(IV), thorium(IV), and uranium(VI) do not react with the ligand under similar experimental conditions. Furoic acid (FAH) and picolinic acid(PicH) form various chloro furoates and picolinates when reacted with TiCl 4 , ZrOCl 2 and ThCl 4 , but do not react with SnCl 4 . The various compounds synthesised have been characterised on the basis of elemental analysis, infrared studies, conductivity and thermogravimetric measurements. (author). 1 tab., 10 refs

Limits for the release of uranium compounds to the environment

International Nuclear Information System (INIS)

Lopez, F.; Ferruz, P.; Aguayo, A.

1987-01-01

A conservative criteria to be be followed by a Regulatory Body, in order to provide the limits of radioactive material release in the environment, When all the parameters are not available for the optimization of radiation protection is presented. This criteria can be applied to stablishment of radioactive release limits for uranium compounds from the nuclear fuel cycle facilities. (author)

Ion exchange separation of nitrate from uranium compounds and its determination by spectrophotometry and ion chromatography

International Nuclear Information System (INIS)

Pires, M.A.F.; Atalla, L.T.; Abrao, A.

1985-11-01

A procedure for the separation of nitrate from uranium compounds by retaintion of uranyl ion on a cationic ion exchanger and its determination in the effluent is described. Nitrate is analysed by the spectrometric method with 1-phenol-2,4-dissulphonic acid. This determination covers the 1 to 10 μg NO - 3 /mL range and requires an amount of 10 to 100 μg NO - 3 . The main interference is uranium (VI) due its own intense yellow color. This difficulty is overcome by the complete separation of UO 2 ++ with the cationic resin. Alternatively, the ion chromatography technique is used for the determination of nitrate in the effluent of the cationic resin. The determination was easily made by the comparison of the nitrate peak hights of the analyte and the standard solutions. The ion chromatography method is very sensitive (0,3 μg NO - 3 /mL), reproducible and suitable for routine analysis and permits the determination of fraction of part per million of nitrate in uranium. The results of nitrate determination using both spectrophotometric and ion chromatography techniques are compared. The method is being routinely applied for the quality control of uranium compounds in the fuel cycle, specially uranium oxide, ammonium diuranate, uranium peroxide and ammonium uranyl tricarbonate. (Author) [pt

High loading uranium plate

International Nuclear Information System (INIS)

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

1990-01-01

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

Precise coulometric titration of uranium in a high-purity uranium metal and in uranium compounds

International Nuclear Information System (INIS)

Tanaka, Tatsuhiko; Yoshimori, Takayoshi

1975-01-01

Uranium in uranyl nitrate, uranium trioxide and a high-purity uranium metal was assayed by the coulometric titration with biamperometric end-point detection. Uranium (VI) was reduced to uranium (IV) by solid bismuth amalgam in 5M sulfuric acid solution. The reduced uranium was reoxidized to uranium (VI) with a large excess of ferric ion at a room temperature, and the ferrous ion produced was titrated with the electrogenerated manganese(III) fluoride. In the analyses of uranium nitrate and uranium trioxide, the results were precise enough when the error from uncertainty in water content in the samples was considered. The standard sample of pure uranium metal (JAERI-U4) was assayed by the proposed method. The sample was cut into small chips of about 0.2g. Oxides on the metal surface were removed by the procedure shown by National Bureau of Standards just before weighing. The mean assay value of eleven determinations corrected for 3ppm of iron was (99.998+-0.012) % (the 95% confidence interval for the mean), with a standard deviation of 0.018%. The proposed coulometric method is simple and permits accurate and precise determination of uranium which is matrix constituent in a sample. (auth.)

The use of voltammetry for determining uranium and associated elements in compounds of nuclear interest

International Nuclear Information System (INIS)

Carvalho, F.M.S. de.

1988-01-01

The determination of uranium and some trace elements found as impurities in nuclear materials by the voltammetric technique using the hanging mercury drop electrode is presented. Emphasis is given to the determination of uranium, of major interest. Europium and ytterbium are simultaneously determined in fractions of individual lanthanides. A procedure for the simultaneous determination of copper, cadmium, nickel and zinc in water, industrial effluents and uranium compounds is discussed. The advantage of the procedure is its simplicity and easiness of execution, with excellent precision and accuracy. (author) [pt

Comprehensive uranium thiophosphate chemistry: Framework compounds based on pseudotetrahedrally coordinated central metal atoms

International Nuclear Information System (INIS)

Neuhausen, Christine; Panthoefer, Martin; Tremel, Wolfgang; Hatscher, Stephan T.; Urland, Werner

2013-01-01

The new ternary compounds UP 2 S 6 , UP 2 S 7 , U(P 2 S 6 ) 2 , and U 3 (PS 4 ) 4 were prepared from uranium metal, phosphorus pentasulfide, and sulfur at 700 C. The crystal structures were determined by single-crystal X-ray diffraction methods. UP 2 S 6 (I) crystallizes in the ZrP 2 S 6 structure type [tetragonal, P4 2 /m, a = 6.8058(7) Aa, c = 9.7597(14) Aa, Z = 2], which consists of central uranium(IV) atoms coordinated by P 2 S 6 4- anions (staggered conformation). The anions are two-dimensional connectors for four uranium cations arranged in one plane. The structure of UP 2 S 7 (II) [orthorhombic, Fddd, a = 8.9966(15) Aa, b = 15.2869(2) Aa, c = 30.3195(5) Aa, Z = 16] is closely related to the monoclinic ZrP 2 S 7 structure type. It consists of U 4+ cations linked by P 2 S 7 4- ligands, the resulting 3D network contains large pores (diameter approx. 3.5 x 16.7 Aa). In the previously reported compound U(P 2 S 6 ) 2 (III) [I4 1 /a, a = 12.8776(9) Aa, c = 9.8367(10) Aa, Z = 2], the metal atoms are coordinated by four bidentate P 2 S 6 2- ligands. This arrangement can be considered as a pseudotetrahedral coordination of the uranium atoms by the linear ligands. Three of the resulting diamondoid frameworks are inseparably interwoven in order to optimize space filling. U 3 (PS 4 ) 4 (IV) [I4 1 /acd, a = 10.7440(9) Aa, c = 19.0969(2) Aa, Z = 2] crystallizes in a defect variant of the PrPS 4 structure type, with 50 % of the U2 sites statistically occupied with uranium atoms. The resulting stoichiometry is U 3 (PS 4 ) 4 with tetravalent uranium atoms. The structure of U 3 (PS 4 ) 4 consists of uranium atoms connected by PS 4 3- groups, each PS 4 group linking four central uranium atoms. Vibrational spectra, which were recorded for I-III, show good agreement between the obtained results and the expected values for the anionic units, while magnetic measurements confirm the presence of tetravalent uranium. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGa

Tema 1: HTTP y aplicaciones web

OpenAIRE

Colomina Pardo, Otto; Arques Corrales, Pilar; Montoyo Bojo, Javier

2011-01-01

En este tema se introduce el funcionamiento básico del protocolo HTTP, que es el que se usa en las comunicaciones cliente-servidor en aplicaciones web. Además se hace una introducción a las herramientas y plataformas de desarrollo de aplicaciones web.

Determination of 17 impurity elements in nuclear quality uranium compounds by atomic absorption spectroscopy

International Nuclear Information System (INIS)

Andonie, O.; Smith, L.A.; Cornejo, S.

1985-01-01

A method is described for the determination of 17 elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, V and Zn) in the ppm level, in nuclearly pure uranium compounds by flame atomic absorption spectroscopy. The analysis is performed by first dissolving the uranium sample in nitric acid and then extracting the uranium with tributyl phosphate solution. The aqueous phase, free of uranium, which contains the elements to analyze is inspirated into the flame of an atomic absorption spectrophotometer using air-acetylene or nitrous oxide-acetylene flame according to the element in study. This method allows to extract the uranium selectively in more than 99.0% and the recovery of the elements sudied was larger 90% (for K) to 100% (for Cr). The sensitivity of the method vary from 0.096 μg/g U (for Cd) to 5.5 μg/g U (for Na). (Author)

Kinetic study of the fluorination by fluorine of some uranium and plutonium compounds; Etude cinetique de la fluoration par le fluor de quelques composes de l'uranium et du plutonium

Energy Technology Data Exchange (ETDEWEB)

Vandenbussche, G [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-12-15

The study of fluorination reactions of uranium and plutonium compounds with elementary fluorine, has been carried out using a thermogravimetric method. These reactions are heterogeneous ones, and of the following type: S(solid) + G{sub 1}(gas) - G{sub 2}(gas). The kinetics of these reactions correspond to a uniform attack of the entire surface of the sample. {alpha}: being the degree of completion of the reaction, k(rel): being the relative rate of penetration of the reaction interface, t: being the time, one have the relation: (1-{alpha}){sup 1/3} = 1 - k(rel)*t. The mechanism of the reaction varies according to the nature of the compound: 1) with uranium tetrafluoride and plutonium tetrafluoride, the reaction proceeds in a single step; 2) with uranium oxides, the reaction proceeds in two steps, uranium oxyfluoride being the intermediate compound; 3) with plutonium oxide, the reaction proceeds in two steps, plutonium tetrafluoride being the intermediate compound; and 4) with uranium trichloride, the mechanism is complex: chlorine trifluoride is formed. (author) [French] L'etude des reactions de fluoration par le fluor, de composes de l'uranium et du plutonium a ete faite par thermogravimetrie. Ce sont des reactions heterogenes du type: S(solide) + G{sub 1}(gaz) - G{sub 2}(gaz). La cinetique de ces reactions est celle correspondant a une attaque uniforme de toute la surface de l'echantillon. Si {alpha}: est le degre d'avancement de la reaction, k(rel): est la vitesse relative d'avancement d'un interface reactionnel, t: le temps. On a la relation: (1-{alpha}){sup 1/3} = 1-k(rel)*t. Le mecanisme de la reaction varie selon la nature du compose: 1) tetrafluorure d'uranium et tetrafluorure de plutonium, la reaction s'effectue en un seul stade; 2) Oxydes d'uranium: la reaction s'effectue en deux stades, l'oxyfluorure d'uranium est le compose intermediaire; 3) oxyde de plutonium, la reaction s'effectue en deux stades, la tetrafluorure de plutonium est le compose

Separation of halogens from uranium compounds by means of pyrohydrolysis and their determination by ion chromatography

International Nuclear Information System (INIS)

Pires, M.A.F.; Brandao Filho, D.; Abrao, A.

1987-07-01

This paper describs the determination of fluorine in nuclear grade uranium compounds by means of phyrohydrolysis. A stream of wet oxygem at a temperature of 900 to 1000 0 C is passed through a quartz tube where the powdered samples is put. The halogens are volatilized as their respective acids that are absorbed in a buffer solution or water. The measurements are made with ion-seletive eletrodes or by ion chromatography. The sensitivity is of 1μg F - /g and 5μg Cl - /g. The separation of fluorine from uranium compounds by diferent methods is discussed. (Author) [pt

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.

Reactions of uranium (III) and (IV) compounds with ketones, nitriles and acid chlorides. Towards a use of uranium complexes in organic synthesis

International Nuclear Information System (INIS)

Adam, Raymond

1993-01-01

In this research thesis, the author shows that various organic molecules can be interestingly transformed into uranium complexes with degrees of oxidation of +3 or +4. In a first part, the author describes reactions of carbonyl compounds with the UCl 4 -Na(Hg) reducing system. Then, he addresses reductions of ketones, nitriles and acid chlorides by a uranium (III) complex: Cp 3 U(THF). The third part reports a detailed study of the reduction of ketones by U(BH 4 ) 4 [fr

Uranium

International Nuclear Information System (INIS)

Hamdoun, N.A.

2007-01-01

The article includes a historical preface about uranium, discovery of portability of sequential fission of uranium, uranium existence, basic raw materials, secondary raw materials, uranium's physical and chemical properties, uranium extraction, nuclear fuel cycle, logistics and estimation of the amount of uranium reserves, producing countries of concentrated uranium oxides and percentage of the world's total production, civilian and military uses of uranium. The use of depleted uranium in the Gulf War, the Balkans and Iraq has caused political and environmental effects which are complex, raising problems and questions about the effects that nuclear compounds left on human health and environment.

Standard test method for determination of impurities in nuclear grade uranium compounds by inductively coupled plasma mass spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the determination of 67 elements in uranium dioxide samples and nuclear grade uranium compounds and solutions without matrix separation by inductively coupled plasma mass spectrometry (ICP-MS). The elements are listed in Table 1. These elements can also be determined in uranyl nitrate hexahydrate (UNH), uranium hexafluoride (UF6), triuranium octoxide (U3O8) and uranium trioxide (UO3) if these compounds are treated and converted to the same uranium concentration solution. 1.2 The elements boron, sodium, silicon, phosphorus, potassium, calcium and iron can be determined using different techniques. The analyst's instrumentation will determine which procedure is chosen for the analysis. 1.3 The test method for technetium-99 is given in Annex A1. 1.4 The values stated in SI units are to be regarded as standard. 1.5 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 ...

Semi-automatic version of the potentiometric titration method for characterization of uranium compounds

International Nuclear Information System (INIS)

Cristiano, Bárbara F.G.; Delgado, José Ubiratan; Wanderley S da Silva, José; Barros, Pedro D. de; Araújo, Radier M.S. de; Dias, Fábio C.; Lopes, Ricardo T.

2012-01-01

The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. - Highlights: ► A semi-automatic potentiometric titration method was developed for U charaterization. ► K 2 Cr 2 O 7 was the only certified reference material used. ► Values obtained for U 3 O 8 samples were consistent with certified. ► Uncertainty of 0.01% was useful for characterization and intercomparison program.

Method and apparatus for separating uranium isotopes

International Nuclear Information System (INIS)

Bernstein, E.R.

1977-01-01

A uranium compound in the solid phase (uranium borohydride four) is subjected to radiation of a first predetermined frequency that excites the uranium-235 isotope-bearing molecules but not the uranium-238 isotope-bearing molecules. The compound is simultaneously subjected to radiation of a second predetermined frequency which causes the excited uranium-235 isotope-bearing molecules to chemically decompose but which does not affect the uranium-238 isotope-bearing molecules. Sufficient heat is then applied to the irradiated compound in the solid phase to vaporize the non-decomposed uranium-238 isotope-bearing molecules but not the decomposed uranium-235 isotope-bearing molecules, thereby physically separating the uranium-235 isotope-bearing molecules from the uranium-238 isotope-bearing molecules. The uranium compound sample in the solid phase is deposited or grown in an elongated tube supported within a dewar vessel having a clear optical path tail section surrounded by a coolant. Two sources of radiation are focused on the uranium compound sample. A heating element is attached to the elongated tube to vaporize the irradiated compound

INTEGRACIÓN DE APLICACIONES EN LAS EMPRESAS

Directory of Open Access Journals (Sweden)

Odalys Jordán Enríquez

2006-04-01

Full Text Available

La integración de aplicaciones es el proceso de lograr que aplicaciones independientes trabajen juntas para producir un conjunto unificado de funcionalidades. Los desarrolladores de aplicaciones siempre tienen que lograr comunicar disímiles arquitecturas de información y hacer interoperar diferentes tecnologías, incluyendo sistemas operativos, lenguajes de programación, plataformas de aplicaciones y sistemas gestores de bases de datos. Las soluciones de integración pueden tener muchas variantes y estar presentes a varios niveles. En este trabajo se abordan los desafíos de la integración, criterios a considerar al realizar la integración y cuatro tipos de integración de aplicaciones. En estos tipos de soluciones presentadas, los patrones de la solución son el enfoque, no las implementaciones.

Spectrographic determination of lanthanides in high-purity uranium compounds, after chromatographic separation by alumina-hydrofluoric acid

International Nuclear Information System (INIS)

Lordello, A.R.; Abrao, A.

1979-01-01

A method is presented for the determination of fourteen rare earth elements in high-purity uranium compounds by emission spectrography. The rare earths are chromatographically separated from uranium by using alumina-hydrofluoric acid. Lanthanum is used both as collector and internal standard. The technique of excitation involves a total consumption of the sample in a 17 ampere direct current arc. The range of determination is about 0.005 to 0.5 μg/g uranium. The coefficient of variation for Pr, Ho, Dy, Er, Tm, Lu, Gd and Tb amounts to 10%. (Author) [pt

Review of experience gained in fabricating nuclear grade uranium and thorium compounds and their analytical quality control at the Instituto de Energia Atomica, Sao Paulo, Brazil

International Nuclear Information System (INIS)

Abrao, A.; Franca Junior, J.M.; Ikuta, A.

1977-01-01

The main activities developed at 'Instituto de Energia Atomica' Sao Paulo, Brazil, on the recovery of uranium from ores, the purification of uranium and thorium raw concentrates and their transformation in nuclear grade compounds, are reviewed. The design and assemble of pilot facilities for ammonium diuranate (ADV) uranium tetrafluoride, uranium trioxide, uranium oxide microspheres, uranyl nitrate denitration, uranim hexafluoride and thorium compounds are discussed. The establishment of analytical procedures are emphasized [pt

Method of semi-automatic high precision potentiometric titration for characterization of uranium compounds

International Nuclear Information System (INIS)

Cristiano, Barbara Fernandes G.; Dias, Fabio C.; Barros, Pedro D. de; Araujo, Radier Mario S. de; Delgado, Jose Ubiratan; Silva, Jose Wanderley S. da; Lopes, Ricardo T.

2011-01-01

The method of high precision potentiometric titration is widely used in the certification and characterization of uranium compounds. In order to reduce the analysis and diminish the influence if the annalist, a semi-automatic version of the method was developed at the safeguards laboratory of the CNEN-RJ, Brazil. The method was applied with traceability guaranteed by use of primary standard of potassium dichromate. The standard uncertainty combined in the determination of concentration of total uranium was of the order of 0.01%, which is better related to traditionally methods used by the nuclear installations which is of the order of 0.1%

Contribution to the monitoring of workers exposed to non-transferable uranium compounds

International Nuclear Information System (INIS)

Camarasa, J.; Chalabreysse, J.

1980-01-01

After a short review of the present knowledge on uranium (metabolism, toxicity, principles of radiotoxicological monitoring), the authors' experience in the surveillance of workers exposed to natural non-transferable uranium compounds (oxides, tetrafluorides) is presented. When setting up urinary controls in a workers' population, a number of difficulties were met in the way of collecting urine samples, obtaining samples free of exogen contribution, interpreting results. The working environment was also studied: three types of pollution measurements were carried out: on the atmosphere at fixed places by measuring the radioactivity of air sample, on work-places and workers by chemical analysis and counting of uranium. Original graphs on work-place monitoring are up-dated regularly. Workers' surveillance by urinary and working condition controls are now well codified. However, further studies will be carried out on man, on working atmospheres, and on the substances handled. The surveillance will then cover working conditions from all points of view [fr

Benchmarking the DFT+U method for thermochemical calculations of uranium molecular compounds and solids.

Science.gov (United States)

Beridze, George; Kowalski, Piotr M

2014-12-18

Ability to perform a feasible and reliable computation of thermochemical properties of chemically complex actinide-bearing materials would be of great importance for nuclear engineering. Unfortunately, density functional theory (DFT), which on many instances is the only affordable ab initio method, often fails for actinides. Among various shortcomings, it leads to the wrong estimate of enthalpies of reactions between actinide-bearing compounds, putting the applicability of the DFT approach to the modeling of thermochemical properties of actinide-bearing materials into question. Here we test the performance of DFT+U method--a computationally affordable extension of DFT that explicitly accounts for the correlations between f-electrons - for prediction of the thermochemical properties of simple uranium-bearing molecular compounds and solids. We demonstrate that the DFT+U approach significantly improves the description of reaction enthalpies for the uranium-bearing gas-phase molecular compounds and solids and the deviations from the experimental values are comparable to those obtained with much more computationally demanding methods. Good results are obtained with the Hubbard U parameter values derived using the linear response method of Cococcioni and de Gironcoli. We found that the value of Coulomb on-site repulsion, represented by the Hubbard U parameter, strongly depends on the oxidation state of uranium atom. Last, but not least, we demonstrate that the thermochemistry data can be successfully used to estimate the value of the Hubbard U parameter needed for DFT+U calculations.

Use of an ion mobility spectrometer for detecting uranium compounds.

Science.gov (United States)

McLain, Derek R; Steeb, Jennifer L; Smith, Nicholas A

2018-07-01

The safeguards community currently lacks a method to rapidly determine the chemical form of radioactive and non-radioactive compounds in real time during inspection activities. Chemical speciation identification can provide important information on both the types of materials that are collected during environmental sampling and can inform inspectors as to where to focus efforts during inspections or complementary access visits. Ion Mobility Spectrometry (IMS) is an established field technique for the detection of explosives, narcotics, and other organic compounds. More recently, electrospray ionization (ESI) has been used to introduce inorganic compounds to IMS instruments for analysis. These techniques have shown the ability to supply chemical information on the compounds analyzed. Although these laboratory based instruments use a liquid-based injection system, there is evidence in the literature of unaltered and intact pharmaceutical tablets being volatilized and ionized in open atmosphere using heat and a Ni-63 source. This work determined that a commercial-off-the-shelf (COTS) IMS could be used for the identification of solid uranium compounds directly after sampling using a COTS sample swipe. Copyright © 2018 Elsevier B.V. All rights reserved.

QRLabel y Blackbird: 2 aplicaciones accesibles para Android

OpenAIRE

Mercade Aguila, Gisela

2012-01-01

El objetivo de este proyecto es el de realizar dos aplicaciones para dispositivos móviles con sistema operativo Android. Estas aplicaciones están ideadas para ser usadas por una persona invidente o con deficiencias visuales. El transcurso del desarrollo de cada aplicacion sirve para conocer y experimentar con diferentes herramientas que dispone este sistema operativo, y de este modo estudiar sus ventajas y limitaciones. Se presentan dispositivos y prototipos de dispositivos diseñados exclusiv...

Lithium alkyl anions of uranium(IV) and uranium(V)

International Nuclear Information System (INIS)

Sigurdson, E.R.; Wilkinson, G.

1977-01-01

Organouranium compounds with six or eight uranium-to-carbon sigma-bonds have been synthesized for the first time. The interaction of uranium tetrachloride with lithium alkyls in diethyl ether leads to the isolation of unstable lithium alkyluranate(IV) compounds of stoicheiometry Li 2 UR 6 .8Et 2 0 (R = Me, CH 2 SiMe 3 . Ph, and o-Me 2 NCH 2 C 6 H 4 ). These lithium salts can also be obtained with other donor solvents, such as tetrahydrofuran or NNN'N'-tetramethylethylenediamine. From uranium pentaethoxide similar lithium salts of stoicheiometry Li 3 UR 8 .3 dioxan (R = Me, CH 2 CMe 3 , and CH 2 SiMe 3 ) can be obtained. The interaction of uranium(VI) hexaisopropoxide with lithium, magnesium, or aluminium alkyls does not give compounds containing U-C bonds, but green oils, e.g. U(OPrsup(i)) 6 (MgMe 2 ) 3 , that appear to be adducts in which the oxygen atom of the isopropoxide group bound to uranium is acting as a donor. I.r. and n.m.r. spectroscopy and analytical data for the new compounds are presented. (author)

Study of resolution enhancement methods for impurities quantitative analysis in uranium compounds by XRF

Energy Technology Data Exchange (ETDEWEB)

Silva, Clayton P.; Salvador, Vera L.R.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.; Scapin, Marcos A., E-mail: clayton.pereira.silva@usp.b [Instituto de Pesquisas Energeticas e Nucleares (CQMA/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente

2011-07-01

X-ray fluorescence analysis is a technique widely used for the determination of both major and trace elements related to interaction between the sample and radiation, allowing direct and nondestructive analysis. However, in uranium matrices these devices are inefficient because the characteristic emission lines of elements like S, Cl, Zn, Zr, Mo and other overlap characteristic emission lines of uranium. Thus, chemical procedures to separation of uranium are needed to perform this sort of analysis. In this paper the deconvolution method was used to increase spectra resolution and correct the overlaps. The methodology was tested according to NBR ISO 17025 using a set of seven certified reference materials for impurities present in U3O8 (New Brunswick Laboratory - NBL). The results showed that this methodology allows quantitative determination of impurities such as Zn, Zr, Mo and others, in uranium compounds. The detection limits were shorter than 50{mu}g. g{sup -1} and uncertainty was shorter than 10% for the determined elements. (author)

Study of resolution enhancement methods for impurities quantitative analysis in uranium compounds by XRF

International Nuclear Information System (INIS)

Silva, Clayton P.; Salvador, Vera L.R.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.; Scapin, Marcos A.

2011-01-01

X-ray fluorescence analysis is a technique widely used for the determination of both major and trace elements related to interaction between the sample and radiation, allowing direct and nondestructive analysis. However, in uranium matrices these devices are inefficient because the characteristic emission lines of elements like S, Cl, Zn, Zr, Mo and other overlap characteristic emission lines of uranium. Thus, chemical procedures to separation of uranium are needed to perform this sort of analysis. In this paper the deconvolution method was used to increase spectra resolution and correct the overlaps. The methodology was tested according to NBR ISO 17025 using a set of seven certified reference materials for impurities present in U3O8 (New Brunswick Laboratory - NBL). The results showed that this methodology allows quantitative determination of impurities such as Zn, Zr, Mo and others, in uranium compounds. The detection limits were shorter than 50μg. g -1 and uncertainty was shorter than 10% for the determined elements. (author)

Chemical thermodynamics of uranium

International Nuclear Information System (INIS)

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

URANIUM LEACHING AND RECOVERY PROCESS

Science.gov (United States)

McClaine, L.A.

1959-08-18

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

Usabilidad en aplicaciones móviles

Directory of Open Access Journals (Sweden)

Juan Gabriel Enriquez

2014-06-01

Full Text Available La usabilidad es considerada uno de los factores más importantes dentro de la calidad de un producto de software. Debido a esto es de interés poder contar con metodologías para medir la usabilidad de las aplicaciones. Los métodos de análisis de usabilidad que actualmente se utilizan, métodos clásicos, fueron desarrollados para aplicaciones de escritorio. Con la aparición, el uso masivo y el crecimiento de los dispositivos móviles, especialmente los Smartphones, la medición de usabilidad en aplicaciones móviles se tornó un tema de investigación. Los métodos y métricas actualmente utilizados para medir usabilidad pueden no ser directamente aplicables a este tipo de productos. Los estudios de usabilidad se han efectuado sobre diferentes contextos, recientemente se empezó a considerar la usabilidad en un contexto móvil. Este trabajo examina los métodos y las métricas utilizados para medir usabilidad y pretende analizar que desafíos existen al momento de realizar pruebas de usabilidad en aplicaciones móviles, donde el contexto que cambia continuamente pasa a tener un rol preponderante.

Several experimental applications of gamma ray spectrometry on the analysis of uranium compounds

International Nuclear Information System (INIS)

Korob, Ricardo O.; Blasiyh Nuno, Guillermo A.

2002-01-01

Several experimental applications of gamma ray spectrometry on the analysis of uranium compounds and materials containing it are studied. Special attention is devoted to the correlation between experimental spectra and the decay chains of 235 U and 238 U contained in the analyzed samples. The following applications are discussed: enrichment determination without using calibration standards, determination of uranium concentration, intensities of the gamma rays emitted by the nuclides present in the decay chains of study and the activity of such nuclides. Because of its importance, detailed discussion about the former one is shown. In addition, preliminary results regarding the emission probabilities of the most important gamma rays of 234m Pa are also informed. (author)

Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

International Nuclear Information System (INIS)

Joseph, D.; Jha, S.N.; Nayak, C.; Bhattacharyya, D.; Babu, P. Venu

2014-01-01

Uranium L 3 X-ray absorption edge was measured in various compounds containing uranium in U 4+ , U 5+ and U 5+ oxidation states. The measurements have been carried out at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 synchrotron radiation source at RRCAT, Indore. Energy shifts of ∼ 2-3 eV were observed for U L 3 edge in the U-compounds compared to their value in elemental U. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on U cation in the above compounds. (author)

Airborne uranium, its concentration and toxicity in uranium enrichment facilities

International Nuclear Information System (INIS)

Thomas, J.; Mauro, J.; Ryniker, J.; Fellman, R.

1979-02-01

The release of uranium hexafluoride and its hydrolysis products into the work environment of a plant for enriching uranium by means of gas centrifuges is discussed. The maximum permissible mass and curie concentration of airborne uranium (U) is identified as a function of the enrichment level (i.e., U-235/total U), and chemical and physical form. A discussion of the chemical and radiological toxicity of uranium as a function of enrichment and chemical form is included. The toxicity of products of UF 6 hydrolysis in the atmosphere, namely, UO 2 F 2 and HF, the particle size of toxic particulate material produced from this hydrolysis, and the toxic effects of HF and other potential fluoride compounds are also discussed. Results of an investigation of known effects of humidity and temperature on particle size of UO 2 F 2 produced by the reaction of UF 6 with water vapor in the air are reported. The relationship of the solubility of uranium compounds to their toxic effects was studied. Identification and discussion of the standards potentially applicable to airborne uranium compounds in the working environment are presented. The effectiveness of High Efficiency Particulate (HEPA) filters subjected to the corrosive environment imposed by the presence of hydrogen fluoride is discussed

Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds

Energy Technology Data Exchange (ETDEWEB)

Pitchaiah, K.C.; Sujatha, K.; Rao, C.V.S. Brahmmananda; Subramaniam, S.; Sivaraman, N.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

2015-06-01

In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO{sub 2}) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO{sub 3}. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO{sub 3} medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO{sub 2} containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.

Synthesis of graphite intercalation compound of group VI metals and uranium hexafluorides

International Nuclear Information System (INIS)

Fukui, Toshihiro; Hagiwara, Rika; Ema, Keiko; Ito, Yasuhiko

1993-01-01

Systematic investigations were made on the synthesis of graphite intercalation compounds of group VI transition metals (W and Mo) and uranium hexafluorides. The reactions were performed by interacting liquid or gaseous metal hexafluorides with or without elemental fluorine at ambient temperature. The degree of intercalation of these metal fluorides depends on the formation enthalpy of fluorometallate anion from the original metal hexafluoride, as has been found for other intercalation reactions of metal fluorides. (author)

Method for producing uranium atomic beam source

International Nuclear Information System (INIS)

Krikorian, O.H.

1976-01-01

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

Fluorination of uranium compounds by gaseous bromine trifluoride and a bromine-fluorine mixture

International Nuclear Information System (INIS)

Sakurai, Tsutomu

1976-03-01

This report summarizes the studies of fluorination of uranium compounds by gaseous BrF 3 and a Br 2 -F 2 mixture, which were carried out in Fluorine Chemistry Laboratory of JAERI in connection with the reprocessing method of nuclear fuels. Although thermodynamically more stable than F 2 , BrF 3 has higher reactivity at relatively low temperatures: fluorination of uranium compounds can be carried out at 100 0 -- 200 0 C by using gaseous BrF 3 . This fluorination temperature is lower than those of F 2 , BrF 5 , ClF and SF 4 , and close to that of ClF 3 . The usage of BrF 3 has however the drawbacks that it requires additional devices to heat the corrosive liquid and to remove Br 2 produced as a byproduct. In order to eliminate the difficulties indicated, a new method of fluorination was developed - the use of a Br 2 -F 2 mixture. Addition of small amounts of Br 2 to the fluorine flow (about 6% in relation to the fluorine concentration) gives marked effects on the rate of fluorination. (auth.)

Aplicaciones farmacéuticas del quitosano

OpenAIRE

Montalvo Aique, Pedro Luis; Montalvo Aique, Pedro Luis; Montalvo Aique, Pedro Luis

2009-01-01

Entre los temas que se trataran en este informe es sobre el quitosano como una breve reseña histórica donde hablaré sobre las fuentes y métodos de obtención de la quitina, caracterización del quitosano, aplicaciones generales del quitosano, derivados del quitosano de mayor importancia, modificación química del quitosano, quitosanos en diversas formas y las aplicaciones farmacéuticas del quitosano como la liberación de fármacos. La actividad industrial de procesado de los productos de la pe...

Study on the characterization and thermal decomposition of uranium compounds by thermogravimetry (TG) and differential scanning calorimetry (DSC)

International Nuclear Information System (INIS)

Dantas, J.M.; Abrao, A.

1981-04-01

A contribution to the characterization of several uranium compounds obtained at the IPEN' Uranium Pilot Plant is given. Particularly, samples of ammonium diuranate (ADU) and uranium oxides were studied. The main objective was to know the stoichiometry of the ADU and the oxides resulting from its thermal transformation. ADU samples were prepared by batchwise precipitation, stationary dewatering into stove and batchwise thermal decomposition, or, alternatively, continuous precipitation, continuous filtration, continuous drying and continuous thermal decomposition inside a temperature gradient electrical furnace. All ADU were precipitated using NH 3 gas from uranul sulfate or uranyl nitrate solutions. The thermal decomposition of ADU and uranium oxides were studied in an air atmosphere by thermogravimetry (TG) and differential scanning calorimetry (DSC). Any correlation between the parameters of precipitation, drying, calcination and the hystory of the obtaintion of the several uraniumm compounds and their initial and final composition was looked for. Heating program was established to have the U 3 O 8 oxide as the final product. Intermediary phases were tentatively identified. Temperatures at which occurred the absorption water elimination, crystallization water elimination, evolution or oxidation of NH 3 , decomposition of NO -3 ion and oxygen evolution and the exo- and endothermic process for each sample were identified. (Author) [pt

Uso de las TIC en el Trastorno de Espectro Autista: aplicaciones

Directory of Open Access Journals (Sweden)

Susana García Guillén

2016-11-01

Full Text Available A través de este trabajo de investigación se ha realizado una revisión bibliográfica detallada sobre el uso de las aplicaciones y el autismo. En primer lugar se ha realizado un recorrido histórico a través del concepto autismo y las aplicaciones disponibles. Los objetivos generales han sido conocer la evolución del término autismo, conocer la bibliografía relacionada con el autismo y el uso de aplicaciones, así como las aplicaciones disponibles para niños autistas. A través de las dos bases de datos, dialnet y google aplicaciones, se presenta la revisión sistemática realizada. Como resultado, se han seleccionado cuatro artículos a través de la base de datos dialnet y treinta y cinco aplicaciones. Las Tecnologías de la Información y Comunicación (TIC ofrecen a los usuarios diferentes beneficios como la estimulación de los sentidos y el desarrollo de habilidades que le ayuden a la integración, mejorando sus habilidades sociales para lograr una mejor relación con sus iguales.

Determination of oxygen in uranium compounds using sulfur monochloride; Dosage de l'oxygene dans les composes de l'uranium par la methode au monochlorure de soufre

Energy Technology Data Exchange (ETDEWEB)

Baudin, G; Besson, J; Blum, P L; Tran-Van, Danh [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1964-07-01

The authors have described in an other paper (Anal. Chim. Acta, in press) a method for oxygen determination in uranium compounds, in which the sample is attacked by sulfur monochloride. The present paper is concerned with the experimental aspects of the method: apparatus procedure. (authors) [French] Les auteurs ont decrit dans une autre publication (Anal. Chim. Acta) a paraitre, une methode de dosage de l'oxygene dans les composes de l'uranium par attaque par le monochlorure de soufre, La presente note a pour but d'en preciser les techniques experimentale: appareillage, mode operatoire. (auteurs)

Vibrational spectroscopy and structural analysis of complex uranium compounds (review)

International Nuclear Information System (INIS)

Umreiko, D.S.; Nikanovich, M.V.

1985-01-01

The paper reports on the combined application of experimental and theoretical methods of vibrational spectroscopy together with low-temperature luminescence data to determine the characteristic features of the formation and structure of complex systems, not only containing ligands directly coordinated to the CA uranium, but also associated with the extraspherical polyatomic electrically charged particles: organic cations. These include uranyl complexes and heterocyclical amines. Studied here were compounds of tetra-halouranylates with pyridine and its derivates, as well as dipyridyl, quinoline and phenanthroline. Structural schemes are also proposed for other uranyl complexes with protonated heterocyclical amines with a more complicated composition, which correctly reflect their spectroscopic properties

Usabilidad en aplicaciones móviles

OpenAIRE

Juan Gabriel Enriquez; Sandra Isabel Casas

2014-01-01

La usabilidad es considerada uno de los factores más importantes dentro de la calidad de un producto de software. Debido a esto es de interés poder contar con metodologías para medir la usabilidad de las aplicaciones. Los métodos de análisis de usabilidad que actualmente se utilizan, métodos clásicos, fueron desarrollados para aplicaciones de escritorio. Con la aparición, el uso masivo y el crecimiento de los dispositivos móviles, especialmente los Smartphones, la medición de usabilidad en ap...

Purification of uranium metal

International Nuclear Information System (INIS)

Suzuki, Kenji; Shikama, Tatsuo; Ochiai, Akira.

1993-01-01

We developed the system for purifying uranium metal and its metallic compounds and for growing highly pure uranium compounds to study their intrinsic physical properties. Uranium metal was zone refined under low contamination conditions as far as possible. The degree of the purity of uranium metal was examined by the conventional electrical resistivity measurement and by the chemical analysis using the inductive coupled plasma emission spectrometry (ICP). The results show that some metallic impurities evaporated by the r.f. heating and other usual metallic impurities moved to the end of a rod with a molten zone. Therefore, we conclude that the zone refining technique is much effective to the removal of metallic impurities and we obtained high purified uranium metal of 99.99% up with regarding to metallic impurities. The maximum residual resistivity ratio, the r.r.r., so far obtained was about 17-20. Using the purified uranium, we are attempting to grow a highly pure uranium-titanium single crystals. (author)

Aplicaciones industriales de la tecnología nuclear

OpenAIRE

Vargas, Celso

2013-01-01

Las aplicaciones industriales de la tecnología nuclear son muydiversas a nivel mundial. En Costa Rica se ha comenzado a introducir este tipo de tecnología para evaluar y mejorar diferentes procesos industriales. Estas aplicaciones se clasifican en dos o en tres categorías, según el criterio utilizado. Están los sistemasde control nucleónico, el perfilaje gamma y los radiotrazadores.

Epidemiological study of workers employed in the French nuclear fuel industry and analysis of the health effects of uranium compounds according to their solubility

International Nuclear Information System (INIS)

Zhivin, Sergey

2015-01-01

External γ-radiation exposure has been shown to be associated with mortality risk due to leukemia, solid cancer, and, possibly, circulatory diseases (CSD). By contrast, little information is available on health risks following the internal contamination, especially the inhalation of uranium compounds with respect to their physicochemical properties (PCP), such as solubility, isotopic composition and others. The aim of this PhD thesis was to estimate mortality risk of cancer and non-cancer diseases in French nuclear fuel cycle workers and comprises three objectives: (1) evaluation of the impact of uranium on mortality through a critical literature review, (2) analysis of cancer and non-cancer mortality in a cohort of uranium enrichment workers, (3) analysis of the relationship between CSD mortality and internal uranium dose in AREVA NC Pierrelatte workers. Existing epidemiological data on uranium PCP and associated health outcomes are scarce. Studies of nuclear fuel cycle workers by sub-groups within the specific stage of the cycle (e.g., uranium enrichment and fuel fabrication) are considered the most promising to shed light on the possible associations, given that such sub-groups present the advantage of a more homogenous uranium exposure. To study the mortality risk associated with exposure to rapidly soluble uranium compounds, we set up a cohort of 4,688 uranium enrichment workers with follow-up between 1968 and 2008. Individual annual exposure to uranium, external γ-radiation, and other non-radiological hazards (trichloroethylene, heat, and noise) were reconstructed from job-exposure matrixes (JEM) and dosimetry records. Over the follow-up period, 131,161 person-years at risk were accrued and 21% of the subjects had die. Analysis of Standardized Mortality Ratios (SMR) showed a strong healthy worker effect (SMR all deaths 0.69, 95% confidence intervals (CI) 0.65 to 0.74; n=1,010). Exposures to uranium and external γ-radiation were not significantly associated

Chapter 1. General information about uranium. 1.3. Uranium ores

International Nuclear Information System (INIS)

Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

2012-01-01

The uranium ores were described. It was found that uranium ores and natural mineral formations containing uranium and its compounds, can be found in concentrations that are technically possible for industrial utilization and which are economically profitable. It was defined that oxidation levels of uranium minerals have an impact on their reprocessing technology and behavior in hydrometallurgical re partition. It was found that the chemical composition of ores has a decisive importance during selection of their reprocessing method.

Thermodynamic data for uranium and thorium intermetallic compounds: A historical perspective

International Nuclear Information System (INIS)

Alcock, C.B.

1989-01-01

The development of quantitative information concerning the stabilities of uranium and thorium intermetallic compounds since the publication of Rough and Bauer's phase diagram compilation are reviewed. During this era a number of high temperature measurement techniques have been developed, from gas/solid equilibration to mass spectrometry and from high temperature calorimetry to solid state electrochemistry, and the growth of quantitative information has run parallel to this evolution. The amount of experimental effort now appears to be declining, and the task presently of major importance is to integrate and rationalize the quantitative information, an effort which will undoubtedly lead to new experimental initiatives. (orig.)

Aplicaciones multimedia para rehabilitación cognitiva

OpenAIRE

Ortega Bastida, Javier

2016-01-01

Diseño de aplicaciones multimedia que posibilitan la rehabilitación de los pacientes a través de aplicaciones de realidad virtual e interfaces 3D: manipulación virtual de entidades, texto predictivo y dibujo guiado sobre entrono integrado para sistema multisensor para rehabilitación e interacción de personas con discapacidad, tanto motora, como cognitiva. El sistema permite la realización de terapias utilizando distintos modos de interacción hombre-máquina, posibilitando múltiples modos de in...

Solubility of airborne uranium samples from uranium processing plant

International Nuclear Information System (INIS)

Kravchik, T.; Oved, S.; Sarah, R.; Gonen, R.; Paz-Tal, O.; Pelled, O.; German, U.; Tshuva, A.

2005-01-01

Full text: During the production and machining processes of uranium metal, aerosols might be released to the air. Inhalation of these aerosols is the main route of internal exposure of workers. To assess the radiation dose from the intake of these uranium compounds it is necessary to know their absorption type, based on their dissolution rate in extracellular aqueous environment of lung fluid. The International Commission on Radiological Protection (ICRP) has assigned UF4 and U03 to absorption type M (blood absorption which contains a 10 % fraction with an absorption rate of 10 minutes and 90 % fraction with an absorption rate of 140 fays) and UO2 and U3O8 to absorption type S (blood absorption rate with a half-time of 7000 days) in the ICRP-66 model.The solubility classification of uranium compounds defined by the ICRP can serve as a general guidance. At specific workplaces, differences can be encountered, because of differences in compounds production process and the presence of additional compounds, with different solubility characteristics. According to ICRP recommendations, material-specific rates of absorption should be preferred to default parameters whenever specific experimental data exists. Solubility profiles of uranium aerosols were determined by performing in vitro chemical solubility tests on air samples taken from uranium production and machining facilities. The dissolution rate was determined over 100 days in a simultant solution of the extracellular airway lining fluid. The filter sample was immersed in a test vial holding 60 ml of simultant fluid, which was maintained at a 37 o C inside a thermostatic bath and at a physiological pH of 7.2-7.6. The test vials with the solution were shaken to simulate the conditions inside the extracellular aqueous environment of the lung as much as possible. The tests indicated that the uranium aerosols samples taken from the metal production and machining facilities at the Nuclear Research Center Negev (NRCN

Study of reactions between uranium-plutonium mixed oxide and uranium nitride and between uranium oxide and uranium nitride; Etude des reactions entre l`oxyde mixte d`uranium-plutonium et le nitrure d`uranium et entre l`oxyde d`uranium et le nitrure d`uranium

Energy Technology Data Exchange (ETDEWEB)

Lecraz, C

1993-06-11

A new type of combustible elements which is a mixture of uranium nitride and uranium-plutonium oxide could be used for Quick Neutrons Reactors. Three different studies have been made on the one hand on the reactions between uranium nitride (UN) and uranium-plutonium mixed oxide (U,Pu)O{sub 2}, on the other hand on these between UN and uranium oxide UO{sub 2}. They show a sizeable reaction between nitride and oxide for the studied temperatures range (1573 K to 1973 K). This reaction forms a oxynitride compound, MO{sub x} N{sub y} with M=U or M=(U,Pu), whose crystalline structure is similar to oxide`s. Solubility of nitride in both oxides is studied, as the reaction kinetics. (TEC). 32 refs., 48 figs., 22 tabs.

Seguridad de aplicaciones híbridas para dispositivos móviles

OpenAIRE

Pérez-Pérez, Iván

2014-01-01

El presente Trabajo Fin de Máster consiste en un estudio comparativo de las distintas soluciones para el desarrollo de aplicaciones híbridas para móviles (esto es, aplicaciones diseñadas con tecnologías web, pero empaquetadas en contenedores nativos) desde el punto de vista de la seguridad. Se realizará un análisis sobre el estado actual de las aplicaciones híbridas y las tecnologías que se emplean en la creación de las mismas. Se desarrollará una prueba de concepto usando u...

Applied internal dosimetry staff exposed to Uranium

International Nuclear Information System (INIS)

Trotta, Marisa V.; Arguelles, Maria G.

2009-01-01

Dosimetric calculations are performed in order to estimate the quantity of a radionuclide that is incorporated by a worker. Urine determinations of activity and mass of uranium are made in the laboratory of Personal and Area Dosimetry. The paper presents reference values concerning the activity excreted in urine due to the incorporation of uranium compounds. The compounds analyzed are natural uranium and uranium enriched to 20 %, both soluble and insoluble. According to the limits allowed for the incorporation of uranium compounds of Type F and M, we verify that the times of monitoring and the detection limits of the equipment used to determine the activity are appropriate. On the other hand, the S-type compounds determination in urine is useful in cases of accidental incorporations (above the ALI) as a first and quick estimate; MDA (0.017 Bq / L) does not allow detection in routine monitoring; measurement in lungs, and faeces should be included. (author)

Reconfigurando aplicaciones multi-cloud con líneas de producto software dinámicas

OpenAIRE

Cubo, Javier; Gámez,Nadia; Pimentel, Ernesto; Fuentes, Lidia

2016-01-01

La reconfiguración dinámica de aplicaciones multi-cloud es un reto complejo aún no suficientemente explorado. En estos entornos las aplicaciones o sus módulos pueden estar desplegados en diferentes proveedores. Por lo tanto, reconfigurar en tiempo de ejecución estas aplicaciones puede requerir la modificación de la distribución en múltiples y heterogéneos proveedores. Obtener la nueva distribución para que sigan funcionando correctamente las aplicaciones no es una tarea senc...

The determination of the crystal structures of some uranium compounds by means of x-ray and neutron diffraction

International Nuclear Information System (INIS)

Adrian, H.W.W.

1977-10-01

In industrial uranium processing or reprocessing procedures, aqueous uranyl nitrate solutions are an intermediate product. The compounds, whose structures are reported, might prove valuable as alternative crystallization products to existing methods of extracting the uranium from solution. The compounds are obtained by the addition of hydroxylammonium to the uranyl nitrate solution and are of the general formula UO 2 (NH 2 0) 2 .xH 2 0, where x can take the values zero, two, three and four. In addition a compound of the formula UO 2 (NH 2 0) 2 .2(NH 2 CH).2H 2 0 was obtained. The UO 2 (NH 2 0) compound crystallized in a monoclinic crystal form. Crystals large enough for neutron diffraction were not obtained. The structure of the UO 2 (NH 2 0) 2 .2H 2 0 could not be solved because only disordered crystalline material was available. The structure of UO 2 (NH 2 0) 2 .3H 2 0 was solved by means of room- and low-temperature neutron diffraction. The unit cell is orthorhombic. The structure of α-UO 2 (NH 2 0) 2 .4H 2 0 was investigated by means of room-temperature x-ray and room- and low-temperature neutron diffraction. The unit cell is triclinic. This compound strongly resembles the trihydrate. The UO 2 (NH 2 0) 2 .2(NH 2 0H).2H 2 0 compound gave crystals large enough for single crystal x-ray but not neutron diffraction. The unit cell is orthorhombic. The characteristic powder patterns (indexed except for the dihydrate compound) of the above compounds are reported [af

Study on the applicability of structural and morphological parameters of selected uranium compounds for nuclear forensic purposes

Energy Technology Data Exchange (ETDEWEB)

Ho Mer Lin, Doris

2015-03-13

Nuclear forensic science or nuclear forensics, is a relatively young discipline which evolved due to the need of analysing interdicted nuclear or radioactive material, necessary for determining its origin. Fundamentally, nuclear forensic science makes use of measurable material properties, referred to as ''signatures'', which provide hints on the history of the material. As part of the advancement in this multi-faceted field, new signatures are constantly sought after and as well as analytical techniques to efficiently and accurately determine the signatures. The work carried out in this study is part of this fulfilment to investigate new structural and morphological parameters as possible new nuclear forensic signatures for selected uranium compounds. The scientific goals have been oriented into three parts for investigations in this study. Firstly, five different compositions of uranium ore concentrates (UOCs) were prepared in the laboratory under well-defined conditions. These materials were subsequently characterized by several techniques such as X-ray diffraction, thermogravimetry/differential thermal analysis, Infrared and Raman spectroscopy, mass spectrometry, scanning electron microscopy etc. Such materials were pivotal for comparison with the industrial samples. Secondly, several uranium compounds, mainly UOCs were measured using Raman spectroscopy. At least three different Raman spectrometers were used and a comparison made in their performance and suitability for nuclear forensics. Raman spectra of industrial uranium materials were interpreted with regard to compound identification and to determination of (anionic) impurities. Anionic impurities that were present were identified and they could provide clues to the processing history of the samples. Statistical techniques such as principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) were applied to several Raman spectra. The analysis showed that

Study on the applicability of structural and morphological parameters of selected uranium compounds for nuclear forensic purposes

International Nuclear Information System (INIS)

Ho Mer Lin, Doris

2015-01-01

Nuclear forensic science or nuclear forensics, is a relatively young discipline which evolved due to the need of analysing interdicted nuclear or radioactive material, necessary for determining its origin. Fundamentally, nuclear forensic science makes use of measurable material properties, referred to as ''signatures'', which provide hints on the history of the material. As part of the advancement in this multi-faceted field, new signatures are constantly sought after and as well as analytical techniques to efficiently and accurately determine the signatures. The work carried out in this study is part of this fulfilment to investigate new structural and morphological parameters as possible new nuclear forensic signatures for selected uranium compounds. The scientific goals have been oriented into three parts for investigations in this study. Firstly, five different compositions of uranium ore concentrates (UOCs) were prepared in the laboratory under well-defined conditions. These materials were subsequently characterized by several techniques such as X-ray diffraction, thermogravimetry/differential thermal analysis, Infrared and Raman spectroscopy, mass spectrometry, scanning electron microscopy etc. Such materials were pivotal for comparison with the industrial samples. Secondly, several uranium compounds, mainly UOCs were measured using Raman spectroscopy. At least three different Raman spectrometers were used and a comparison made in their performance and suitability for nuclear forensics. Raman spectra of industrial uranium materials were interpreted with regard to compound identification and to determination of (anionic) impurities. Anionic impurities that were present were identified and they could provide clues to the processing history of the samples. Statistical techniques such as principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) were applied to several Raman spectra. The analysis showed that

Phospholyl-uranium complexes

International Nuclear Information System (INIS)

Gradoz, Philippe

1993-01-01

After having reported a bibliographical study on penta-methylcyclopentadienyl uranium complexes, and a description of the synthesis and radioactivity of uranium (III) and (IV) boron hydrides compounds, this research thesis reports the study of mono and bis-tetramethyl-phospholyl uranium complexes comprising chloride, boron hydride, alkyl and alkoxide ligands. The third part reports the comparison of structures, stabilities and reactions of homologue complexes in penta-methylcyclopentadienyl and tetramethyl-phospholyl series. The last part addresses the synthesis of tris-phospholyl uranium (III) and (IV) complexes. [fr

LIQUID METAL COMPOSITIONS CONTAINING URANIUM

Science.gov (United States)

Teitel, R.J.

1959-04-21

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

Synthesis and reactivity of triscyclopentadienyl uranium (III) and (IV) complexes

International Nuclear Information System (INIS)

Berthet, J.C.

1992-01-01

The reactions of (RC 5 H 4 ) 3 U with R=trimethylsilylcyclopentadienyl or tertiobutylcyclopentadienyl are studied for the synthesis of new uranium organometallic compounds. Reactions with sodium hydride are first described uranium (III) anionic hydrides obtained are oxidized for synthesis of stable uranium (IV) organometallic hydrides. Stability of these compounds is discussed. Reactivity of these uranium (III) and (IV) hydrides are studied. Formation of new binuclear compounds with strong U-O and U-N bonds is examined and crystal structure are presented. Monocyclooctatetraenylic uranium complexes are also investigated

Chronic exposure to uranium compounds: medical surveillance problems related to their physico-chemical properties and their solubility: actual data and future prospects

International Nuclear Information System (INIS)

Ansoborlo, E.; Chalabreysse, J.C.

1988-01-01

A method was developped to assess uranium exposure hazards at work stations based on industrial experience acquired in Comurhex Malvesi at Narbonne. Applied to uranium tetrafluoride (UF4), the method involves five steps: 1/ Characterization of the industrial compound, including physico-chemical properties (density, surface area, X-ray spectrum and uranium enrichment). 2/ In vitro biological solubility with different synthetic fluids like Gamble solution added with differents gaz or compounds (Oxygen or hydrogen peroxyde), in order to determine the solubility class D, W or Y. 3/ Assessment of work station concentration in Bq m -3 and particle size distribution (AMAD). 4/ Monitoring workers by routine urinary excretion completed, if necessary, by fecal excretion and γ spectrometry. 5/ Use of individual protection filters or masks. Results and actual data on UF4 are presented and future prospects of studies on calcinated uranates are dealed with [fr

Seguridad de las aplicaciones web

OpenAIRE

Luján Mora, Sergio

2016-01-01

Conferencia "Seguridad de las aplicaciones web" impartida en las III Jornadas Informáticas - UTE 2016 en la Facultad de Ciencias de la Ingeniería e Industrias de la Universidad Tecnológica Equinoccial (Quito, Ecuador) el 5 de julio de 2016.

Plasmachemical synthesis and evaluation of the thermal conductivity of metal-oxide compounds "Molybdenum-uranium dioxide"

Science.gov (United States)

Kotelnikova, Alexandra A.; Karengin, Alexander G.; Mendoza, Orlando

2018-03-01

The article represents possibility to apply oxidative and reducing plasma for plasma-chemical synthesis of metal-oxide compounds «Mo‒UO2» from water-salt mixtures «molybdic acid‒uranyl nitrate» and «molybdic acid‒ uranyl acetate». The composition of water-salt mixture was calculated and the conditions ensuring plasma-chemical synthesis of «Mo‒UO2» compounds were determined. Calculations were carried out at atmospheric pressure over a wide range of temperatures (300-4000 K), with the use of various plasma coolants (air, hydrogen). The heat conductivity coefficients of metal-oxide compounds «Mo‒UO2» consisting of continuous component (molybdenum matrix) are calculated. Inclusions from ceramics in the form of uranium dioxide were ordered in the matrix. Particular attention is paid to methods for calculating the coefficients of thermal conductivity of these compounds with the use of different models. Calculated results were compared with the experimental data.

Uranium chemistry: significant advances

International Nuclear Information System (INIS)

Mazzanti, M.

2011-01-01

The author reviews recent progress in uranium chemistry achieved in CEA laboratories. Like its neighbors in the Mendeleev chart uranium undergoes hydrolysis, oxidation and disproportionation reactions which make the chemistry of these species in water highly complex. The study of the chemistry of uranium in an anhydrous medium has led to correlate the structural and electronic differences observed in the interaction of uranium(III) and the lanthanides(III) with nitrogen or sulfur molecules and the effectiveness of these molecules in An(III)/Ln(III) separation via liquid-liquid extraction. Recent work on the redox reactivity of trivalent uranium U(III) in an organic medium with molecules such as water or an azide ion (N 3 - ) in stoichiometric quantities, led to extremely interesting uranium aggregates particular those involved in actinide migration in the environment or in aggregation problems in the fuel processing cycle. Another significant advance was the discovery of a compound containing the uranyl ion with a degree of oxidation (V) UO 2 + , obtained by oxidation of uranium(III). Recently chemists have succeeded in blocking the disproportionation reaction of uranyl(V) and in stabilizing polymetallic complexes of uranyl(V), opening the way to to a systematic study of the reactivity and the electronic and magnetic properties of uranyl(V) compounds. (A.C.)

La estructura del fullereno C60 y sus aplicaciones

OpenAIRE

Vasilievna Kharissova, Oxana; Ortiz Méndez, Ubaldo

2002-01-01

Se revisan los datos reportados de una nueva clase de materiales basados en los fullerenos. Se explica la estructura del fullereno C60 y sus compuestos con metales alcalinos, sus propiedades y aplicaciones. Se señala que estos compuestos tienen propiedades de superconducción comparable con la de los tradicionales cupratos. Se indica que esta modificación del carbono puede formar nanotubos que tienen varias aplicaciones prácticas debido a sus propiedades.

Aplicaciones sobre plataformas de redes neuronales en tiempo real

OpenAIRE

Tosini, Marcelo Alejandro; Acosta, Nelson

2003-01-01

El presente trabajo pretende el diseño de una metodología para la construcción de aplicaciones basadas en redes neuronales sobre una plataforma Muren. Las aplicaciones se restringen a sistemas de control y reconocimiento de patrones por imágenes. Se describe la arquitectura del sistema de desarrollo Muren, basado en 2 procesadores ZISC de 78 neuronas cada uno, una FPGA Spartan II, bancos de memoria y lógica adicional de comunicación.

Determination of carbon in uranium and its compounds

International Nuclear Information System (INIS)

Perez-Garcia, M. M.

1972-01-01

This paper collects the analytical methods used our laboratories for the determination of carbon in uranium metal, uranate salts and the oxides, fluorides and carbides of uranium. The carbon is usually burned off in a induction or resistance oven under oxygen flow. The CO 2 is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

Spectroscopy and chemistry of uranium IV

International Nuclear Information System (INIS)

Folcher, G.; Rigny, P.

1980-06-01

Different fundamental research papers on uranium IV are presented, some were never edited. Molecular spectroscopy was used for identification and structural study of uranium IV in aqueous or organic solutions. The fields studied are: coordination, stereochemistry, electronic structure and chemical properties. For interpretation of results some studies were made with solid compounds or with thorium compounds or thorium complexes. Knowledge of actinides chemistry is improved, uranium and thorium being models for 5 f ions, extractive chemistry is better understood and new applications are possible [fr

Reference values and their application to the monitoring of occupational exposure to natural uranium compounds

International Nuclear Information System (INIS)

1986-09-01

Natural uranium compounds, which enter the oxide fuel cycle offer physico-chemical characteristics dependent on their structure and their production process. These characteristics govern their biological behaviour and the degree of their radioactive and chemical toxicity. The monitoring of workers occupationnally exposed to these compounds is carried out by bioassays; in order to get the best interpretation, the resulting data must be compared to reference values. These values must be closely related to the type of contaminant and the real exposure conditions. In this report, the occupational medicine services working group has examined the possibilities of obtaining such reference values and suggests recommendations and operational values covering most situations found in routine monitoring [fr

Determination of trace lithium in uranium compounds by adsorption on activated alumina using a micro-column method.

Science.gov (United States)

Luo, Ming-Biao; Li, Bo-Ping; Yang, Zhi; Liu, Wei; Sun, Yu-Zhen

2008-08-01

A novel method using a micro-column packed with active alumina as solid phase was proposed for separation of trace lithium from uranium compounds prior to determination. The method is based on a preliminary chromatographic separation of the total amount of uranium. This separation involves passing the solution containing sodium carbonate through active alumina and then eluting the trace lithium retained by the solid phase with a solution of sulfuric acid. Two modes, off-line and on-line micro-column preconcentration, were performed. In conjunction with atomic absorption spectrometry, this on-line preconcentration technique allows a determination of lithium at 10(-9) level. Both off-line and on-line mode operation conditions were investigated in separation and determination of trace lithium by micro-column method (length of column bed, flow rate, etc.). The adsorption capacity of activated alumina was found to be 343 microg g(-1) for lithium. Under the optimal operation condition, the detection limit (DL) of on-line preconcentration corresponding to three times the standard deviation of the blank (S/N = 3) was found to be 1.3 ng mL(-1) and the RSD of this method is 3.32% (n = 5). The on-line calibration graph was linear over the range 20 - 200 ng mL(-1). A good preconcentration factor 820 was achieved by experiment under the on-line mode. The developed method was applied to the analysis of trace lithium in nuclear grade uranium compounds.

Chapter 1. General information about uranium. 1.10. Uranium application

International Nuclear Information System (INIS)

Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

2011-01-01

Full text: Metallic uranium or its compounds are used as nuclear fuel in nuclear reactors. A natural or low-enriched admixture of uranium isotopes is applied in stationery reactors of nuclear power plants, and products of a high enrichment degree are used in nuclear power plants or in reactors that operates with fast neutrons. 235 U is a source of nuclear energy in nuclear weapons. Depleted uranium is used as armour-piercing core in bombshells. 238 U serves as a source of secondary nuclear fuel - plutonium. (author)

Chapter 1. General information about uranium. 1.10. Uranium application

International Nuclear Information System (INIS)

Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

2012-01-01

Full text: Metallic uranium or its compounds are used as nuclear fuel in nuclear reactors. A natural or low-enriched admixture of uranium isotopes is applied in stationery reactors of nuclear power plants, and products of a high enrichment degree are used in nuclear power plants or in reactors that operates with fast neutrons. 235 U is a source of nuclear energy in nuclear weapons. Depleted uranium is used as armour-piercing core in bombshells. 238 U serves as a source of secondary nuclear fuel - plutonium.

Desarrollo de aplicaciones web

OpenAIRE

Luján Mora, Sergio

2010-01-01

Agradecimientos 1. Introducción a las aplicaciones web 2. Instalación del servidor 3. Diseño de páginas web 4. Formato estructurado de texto: XML 5. Contenido dinámico 6. Acceso a bases de datos: JDBC 7. Servicios web 8. Utilización y mantenimiento 9. Monitorización y análisis Bibliografía GNU Free Documentation License

Manhattan Project Technical Series: The Chemistry of Uranium (I)

International Nuclear Information System (INIS)

Rabinowitch, E. I.; Katz, J. J.

1947-01-01

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.

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.

Determination of uranium in clinical and environmental samples by FIAS-ICPMS

International Nuclear Information System (INIS)

Karpas, Z.; Lorber, A.; Halicz, L.; Gavrieli, I.

1998-01-01

Uranium may enter the human body through ingestion or inhalation. Ingestion of uranium compounds through the diet, mainly drinking water, is a common occurrence, as these compounds are present in the biosphere. Inhalation of uranium-containing particles is mainly an occupational safety problem, but may also take place in areas where uranium compounds are abundant. The uranium concentration in urine samples may serve as an indication of the total uranium body content. A method based on flow injection and inductively coupled plasma mass spectrometry (FIAS-ICPMS) was found to be most suitable for determination of uranium in clinical samples (urine and serum), environmental samples (seawater, wells and carbonate rocks) and in liquids consumed by humans (drinking water and commercial beverages). Some examples of the application of the FIAS-ICPMS method are reviewed and presented here

Uranium compounds in ceramic enamels-radioactivity analysis and use hazards

International Nuclear Information System (INIS)

Cucchi, G.; Amadesi, P.

1980-01-01

An analysis was made of the radioactivity of enamel samples, containing depleted Uranium and Uranium ore, such as employed by the ceramic industry to produce paving and lining tiles. An investigation was also made of various types of tiles with depleted Uranium containing enamels, in order to evaluate the use hazard for dwelling houses, in particular in regard to the wear of tiled floors by children as a critical group. The risk to the population due to the use of tiles dyed with enamel containing depleted Uranium was considered an undue risk and as such not permissible. (U.K.)

Uranium - the element: its occurrence and uses

International Nuclear Information System (INIS)

Awan, I. Z.

2015-01-01

Uranium metal and its compounds have been of great interest to physicists and chemists due to its use for both civil and military applications, e.g. production of electricity, use in the medical field and for making nuclear weapons. This review paper describes the occurrence, chemistry and metallurgy of the element 'uranium', its conversion to stable compounds such as yellow cake, uranium tetrafluoride and uranium hexafluoride and the enrichment technologies and uses for both civil and military purposes. The paper is meant for ready reference for students and teachers in connection with the recent spate of interest shown in nuclear power generation in Pakistan and abroad. (author)

Uso y aplicaciones de drones en minería

OpenAIRE

Sánchez García, Manuel

2017-01-01

Los drones son una tecnología actual y en pleno desarrollo con múltiples aplicaciones pero ¿conocemos todas las posibilidades que nos ofrecen dentro de la minería? Este proyecto pretende dar respuesta a esta pregunta y poner de manifiesto todas las aplicaciones potenciales. Los drones, también conocidos como VANT (Vehículo Aéreo No Tripulado) o UAV (Unmaned Aerial Vehicle), son aeronaves que vuelan sin tripulación, reutilizables, capaz de mantener de manera autónoma un vuelo controlado y ...

Estudio de las aplicaciones de gestión de la red WAN de un operador de telecomunicaciones

OpenAIRE

González Medina, Mariano

2012-01-01

Este proyecto se basa en analizar y estudiar exhaustivamente las aplicaciones de gestión de la red WAN de un operador de telecomunicaciones (OdT). Dichas aplicaciones se dividen en dos fases importantes: provisión y mantenimiento. Aquest projecte es basa en analitzar i estudiar exhaustivament les aplicacions de gestió de la xarxa WAN d'un operador de telecomunicacions (OdT). Aquestes aplicacions es divideixen en dues fases importants: provisió i manteniment.

Uranium induces oxidative stress in lung epithelial cells

International Nuclear Information System (INIS)

Periyakaruppan, Adaikkappan; Kumar, Felix; Sarkar, Shubhashish; Sharma, Chidananda S.; Ramesh, Govindarajan T.

2007-01-01

Uranium compounds are widely used in the nuclear fuel cycle, antitank weapons, tank armor, and also as a pigment to color ceramics and glass. Effective management of waste uranium compounds is necessary to prevent exposure to avoid adverse health effects on the population. Health risks associated with uranium exposure includes kidney disease and respiratory disorders. In addition, several published results have shown uranium or depleted uranium causes DNA damage, mutagenicity, cancer and neurological defects. In the current study, uranium toxicity was evaluated in rat lung epithelial cells. The study shows uranium induces significant oxidative stress in rat lung epithelial cells followed by concomitant decrease in the antioxidant potential of the cells. Treatment with uranium to rat lung epithelial cells also decreased cell proliferation after 72 h in culture. The decrease in cell proliferation was attributed to loss of total glutathione and superoxide dismutase in the presence of uranium. Thus the results indicate the ineffectiveness of antioxidant system's response to the oxidative stress induced by uranium in the cells. (orig.)

Interim guidance for the safe transport of reprocessed uranium

International Nuclear Information System (INIS)

1994-06-01

Increasingly reprocessed uranium is being used for the fabrication of nuclear fuel elements. Different intermediate reprocessing steps are carried out at different locations. Therefore, transportation of uranium material is necessary. Due to the difference in isotope composition of reprocessed uranium then unirradiated uranium a doubt is casted on the presumption that packages used for the transport of unirradiated uranium are automatically suitable for reprocessed uranium compounds. The Standing Advisory Group on the Safe Transport of Radioactive Material (SAGSTRAM) recommended that the issue be reviewed by consultants and that a document be developed that would give guidance to users of the Regulations. This TECDOC is the result of the endeavors of the experts convened at two Consultants Services meetings. It contains guidance on the provisions in the current Regulations as well as proposals for changes to the new Revised Edition whose publication is planned for 1996. This document demonstrates that under the present Transport Regulations it is possible in most cases to ship reprocessed uranium compounds in the same packages as unirradiated uranium compounds. In few cases a more stringent package type is required. 8 refs, 22 figs, 19 tabs

Uranium thiolate complexes

International Nuclear Information System (INIS)

Leverd, Pascal C.

1994-01-01

This research thesis proposes a new approach to the chemistry of uranium thiolate complexes as these compounds are very promising for various uses (in bio-inorganic chemistry, in some industrial processes like oil desulphurization). It more particularly addresses the U-S bond or more generally bonds between polarizable materials and hard metals. The author thus reports the study of uranium organometallic thiolates (tricyclo-penta-dienic and mono-cyclo-octa-tetraenylic complexes), and of uranium homoleptic thiolates (tetra-thiolate complexes, hexa-thiolate complexes, reactivity of homoleptic thiolate complexes) [fr

Production and analysis of ultradispersed uranium oxide powders

Science.gov (United States)

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

2010-05-01

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

Ferromagnetic quantum criticality in the uranium-based ternary compounds URhSi, URhAl, and UCoAl

International Nuclear Information System (INIS)

Combier, Tristan

2014-01-01

In this thesis we explore the ferromagnetic quantum criticality in three uranium-based ternary compounds, by means of thermodynamical and transport measurements on single crystal samples, at low temperature and high pressure. URhSi and URhAl are itinerant ferromagnets, while UCoAl is a paramagnet being close to a ferromagnetic instability. All of them have Ising-type magnetic ordering. In the orthorhombic compound URhSi, we show that the Curie temperature decreases upon applying a magnetic field perpendicular to the easy magnetization axis, and a quantum phase transition is expected around 40 T. In the hexagonal system URhAl, we establish the pressure-temperature phase diagram for the first time, indicating a quantum phase transition around 5 GPa. In the isostructural compound UCoAl, we investigate the metamagnetic transition with measurements of magnetization, Hall effect, resistivity and X-ray magnetic circular dichroism. Some intriguing magnetic relaxation phenomena are observed, with step-like features. Hall effect and resistivity have been measured at dilution temperatures, under hydrostatic pressure up to 2.2 GPa and magnetic field up to 16 T. The metamagnetic transition terminates under pressure and magnetic field at a quantum critical endpoint. In this region, a strong effective mass enhancement occurs, and an intriguing difference between up and down field sweeps appears in transverse resistivity. This may be the signature of a new phase, supposedly linked to the relaxation phenomena observed in magnetic measurements, arising from frustration on the quasi-Kagome lattice of uranium atoms in this crystal structure. (author) [fr

Electrolytic recovery of uranium oxides

International Nuclear Information System (INIS)

Gurr, W.R.

1979-01-01

A method is described for extracting uranium oxide from a solution of one or more uranium compounds, e.g. leach liquors, comprising subjecting the solution to electrolysis utilizing a high current density, e.g. 500 to 4000 amp/m 2 , whereby uranium oxide is formed at the cathode and is recovered. The method is particularly suited to a continuous process using a rotating cathode cell. (author)

Method for preparing a sinterable uranium dioxide powder

International Nuclear Information System (INIS)

Thornton, T.A.; Holaday, V.D. Jr.

1985-01-01

This invention provides an improved method for preparing a sinterable uranium dioxide powder for the preparation of nuclear fuel, using microwave radiation in a microwave induction furnace. The starting compound may be uranyl nitrate hexahydrate, ammonium diuranate or ammonium uranyl carbonate. The starting compound is heated in a microwave induction furnace for a period of time sufficient for compound decomposition. The decomposed compound is heated in a microwave induction furnace in a reducing atmosphere for a period of time sufficient to reduce the decomposed compound to uranium dioxide powder

Dzyaloshinskii-Moriya interaction and magnetic anisotropies in Uranium compounds

Science.gov (United States)

Sandratskii, L. M.

2018-05-01

We report on the first-principles study of complex noncollinear magnetic structures in Uranium compounds. We contrast two cases. The first is the periodic magnetic structure of U2Pd2In with exactly orthogonal atomic moments, the second is an incommensurate plane spiral structure of UPtGe where the angle between atomic moments of nearest neighbors is also close to 90°. We demonstrate that the hierarchy of magnetic interactions leading to the formation of the magnetic structure is opposite in the two cases. In U2Pd2In, the magnetic anisotropy plays the leading role, followed by the Dzyaloshinskii-Moriya interaction (DMI) interaction specifying the chirality of the structure. Here, the interatomic exchange interaction does not play important role. In UPtGe the hierarchy of the interactions is opposite. The leading interaction is the interatomic exchange interaction responsible for the formation of the incommensurate spiral structure followed by the DMI responsible for the selected chirality of the helix. The magnetic anisotropy is very weak that is a prerequisite for keeping the distortion of the helical structure weak.

Rays Emitted by Compounds of Uranium and of Thorium

Indian Academy of Sciences (India)

I examined a large number of metals, salts, oxides, and minerals [2]. The following table gives, for each substance, the magnitude of the current i in amperes (order of magnitude,. 10-11. ). The substances which I studied but omitted from the table are at least 100 times less active than uranium. Uranium containing some ...

Bibliographical study on photochemical separation of uranium isotopes

International Nuclear Information System (INIS)

Bougon, Roland

1975-01-01

The objective of this report is to propose an overview of knowledge and current works on isotopic separation of uranium by means of selective excitation where this excitation is obtained by a light source with a wave length corresponding to a selective or preferential absorption by a molecule or by the atom itself of one of the isotopes. After a brief overview of principles and requirements of isotopic separation by selective excitation, the author reviews compounds which can be used for this process. These compounds are mainly considered in terms of spectroscopy, and the study focuses on the most volatile among them, the uranium hexafluoride, its spectra, and possible processes for extraction. Some much less volatile uranium compounds are also mentioned with, when available, their spectroscopic properties. The uranium vapour excitation process is described, and some orientations for further researches are proposed [fr

The Uranium Chemistry Research Unit

International Nuclear Information System (INIS)

Anon.

1983-01-01

The article discusses the research work done at the Uranium Chemistry Research Unit of the University of Port Elizabeth. The initial research programme dealt with fundamental aspects of uranium chemistry. New uranium compounds were synthesized and their chemical properties were studied. Research was also done to assist the mining industry, as well as on nuclear medicine. Special mentioning is made of the use of technetium for medical diagnosis and therapy

Evaluación de los Frameworks en el Desarrollo de Aplicaciones Web con Python

OpenAIRE

Jimmy Rolando Molina Ríos; Nancy Magaly Loja Mora; Mariuxi Paola Zea Ordóñez; Erika Lizbeth Loaiza Sojos

2016-01-01

Debido a la creciente interacción de los usuarios con sistemas web, surge la necesidad de combinar las funcionalidades de aplicaciones clásicas de escritorio, con la accesibilidad y bajo costo de la publicación de aplicaciones web; dando origen a la elección del mejor marco de trabajo que se adopte a las necesidades de los desarrolladores. Esta investigación presenta un análisis comparativo de los frameworks que trabajan con el lenguaje Python para el desarrollo de aplicaciones web. Para ello...

The possibility of the mixed valence state in the uranium intermetallic compounds: UCoGa5, U2Ru2Sn and U2RuGa8

International Nuclear Information System (INIS)

Troc, Robert

2007-01-01

The mixed valence (MV) phenomenon has been observed so far in a large number of various compounds but containing only lanthanides. These properties are usually associated with the mixing of the localised f-state and the band states. The usual valence state for magnetic uranium intermetallics is the trivalent state 5f 3 or hybridised 5f 2 6d 1 , both are nearly degenerate in energy and can compete for a stability of the compound. In some cases a gain in an energy minimum may be achieved by very fast fluctuating between these two states with a time of 10 -14 s, which does not allow to yield the ordered state even if the exchange interactions (favourite the U-U distances) would be able for that. The latter cases seem to concern the described here intermetallics: one ternary compound based on Co, UCoGa 5 , and the two uranium ternary compounds based on Ru, namely U 2 Ru 2 Sn and U 2 RuGa 8 which all crystallize in a tetragonal unit cell. All these compounds show a maximum in their temperature dependences of the magnetic susceptibility measured along and perpendicular to the c-axis. Such a behaviour, which is reminiscent of a number of Ce (Sm, Eu) and Yb compounds for which χ(T) has in the past been considered by Sales and Wohlleben (SW) by applying their ICF model or by Lawrance et al. following their scaling procedure. It turned out that these phenomenological models can also be applied to the considered here two Ru-based uranium ternaries from which some reliable energy parameters could be found. In order to further support the mixing valence scenario for the first such cases in uranium compounds presented here, the transport and thermodynamic properties are also discussed. However, some of the most important results confirming the MV state, e.g., in U 2 RuGa 8 , has recently been achieved from the inelastic neutron scattering performed in the Rutherford Appleton Laboratory on the ISIS facility. From these measurements a characteristic gap of 60 meV has been

Wavelets y sus aplicaciones

OpenAIRE

Castro, Liliana Raquel; Castro, Silvia Mabel

1995-01-01

Se presenta una introducción a la teorfa de wavelets. Ademas, se da una revisión histórica de cómo fueron introducidas las wavelets para la representación de funciones. Se efectúa una comparación entre la transformada wavelet y la transformada de Fourier. Por último, se presentan también algunas de los múltiples aplicaciones de esta nueva herramienta de análisis armónico.

Solubility of airborne uranium compounds at the Fernald Environmental Management Project

International Nuclear Information System (INIS)

Heffernan, T.E.; Lodwick, J.C.; Spitz, H.; Neton, J.; Soldano, M.

2000-01-01

The in vitro volubility of airborne uranium dusts collected at a former uranium processing facility now undergoing safe shutdown, decontamination and dismantling was evaluated by immersing air filters from high volume samplers in simulated lung fluid and measuring the 238 U in sequential dissolution fractions using specific radiochemical analysis for uranium. X rays and photons from the decay of uranium and thorium remaining on the filter after each dissolution period were also directly measured using a planar germanium detector as a means for rapidly evaluating the volubility of the uranium bearing dusts. Results of these analyses demonstrate that two -distinct types of uranium bearing dusts were collected on the filters depending upon the location of the air samplers. The first material exhibited a dissolution half-time much less than one day and was most likely UO 3 . The dissolution rate of the second material, which was most likely U 3 O 8 , exhibited two components. Approximately one-third of this material dissolved with a halftime much less than one day. The remaining two-thirds of the material dissolved with half times between 230 ± 16 d and 1350 ± 202 d. The dissolution rates for uranium determined by radiochemical analysis and by gamma spectrometry were similar. However, gamma spectrometry analysis suggested a difference between the half times of 238 U and its daughter 234 Th which may have important implications for in vivo monitoring of uranium

Safety criteria of uranium enrichment plants

International Nuclear Information System (INIS)

Nardocci, A.C.; Oliveira Neto, J.M. de

1994-01-01

The applicability of nuclear reactor safety criteria applied to uranium enrichment plants is discussed, and a new criterion based on the soluble uranium compounds and hexafluoride chemical toxicities is presented. (L.C.J.A.). 21 refs, 4 tabs

URANIUM BISMUTHIDE DISPERSION IN MOLTEN METAL

Science.gov (United States)

Teitel, R.J.

1959-10-27

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

Medical effects of internal contamination with uranium.

Science.gov (United States)

Duraković, A

1999-03-01

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

Separation of uranium isotopes by accelerated isotope exchange reactions

International Nuclear Information System (INIS)

Seko, M.; Miyake, T.; Inada, K.; Ochi, K.; Sakamoto, T.

1977-01-01

A novel catalyst for isotope exchange reaction between uranium(IV) and uranium(VI) compounds enables acceleration of the reaction rate as much as 3000 times to make industrial separation of uranium isotopes economically possible

Mashup d'aplicacions basat en un buscador intel·ligent

OpenAIRE

Sancho Piqueras, Javier

2010-01-01

Mashup de funcionalitats, basat en un cercador intel·ligent, en aquest cas pensat per a cursos, carreres màsters, etc. La finalitat és adjuntar diverses aplicacions amb l'únic propòsit que en aquest cas és un buscador però que també ens permet utilitzar eines per a la connectivitat mitjançant web Services, o xarxes socials. Mashup de funcionalidades, basado en un buscador inteligente, en este caso pensado para cursos, carreras másters, etc. La finalidad es juntar diversas aplicaciones con ...

Chapter 3. Classical method of uranium leaching from ores and reasons for incomplete recovery at dumps of State Enterprise 'VOSTOKREDMET'. 3.3. Basic regularities of uranium ores leaching

International Nuclear Information System (INIS)

Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

2012-01-01

Present article is devoted to basic regularities of uranium ores leaching. It was found that the basic method of uranium ores enrichment and producing of reasonably rich and pure uranium concentrates (usually technical uranium oxide) is a chemical concentration concluded in selective uranium leaching from ore raw materials with further, uranium compounds - so called uranium chemical concentrates. Such reprocessing of uranium ores with the purpose of uranium chemical concentrates production, currently, are produced everywhere by hydrometallurgical methods. This method in comparison with enrichment and thermal reprocessing is a universal one. Hydrometallurgy - the part of chemical technology covering so called moist methods of metals and their compounds (in the current case, uranium) extraction from raw materials, where they are contained. It can be ores or ore concentrates produced by radiometric, gravitational, floatation enrichment, sometimes passed through high-temperature reprocessing or even industry wastes. The basic operation in hydrometallurgy is its important industrial element - metal or metals leaching as one or another compound. Leaching is conversion of one or several components to solution under impact of relevant technical solvents: water, water solutions, acids, alkali or base, solution of some salts and etc. The basic purpose of leaching in uranium technology is to obtain the most full and selective solution of uranium.

Review of experience gained in fabricating nuclear grade uranium and thorium compounds and their analytical quality control at the Instituto de Energia Atomica, Sao Paulo, Brazil

International Nuclear Information System (INIS)

Abrao, A.; Franca, J.M. Jr.; Ikuta, A.; Pueschel, C.R.; Federgruen, L.; Lordello, A.R.; Tomida, E.K.; Moraes, S.; Brito, J. de; Gomes, R.P.; Araujo, J.A.; Floh, B.; Matsuda, H.T.

1977-01-01

This paper summarizes the main activities dealing with the fabrication of nuclear grade uranium and thorium compounds at the Instituto de Energia Atomica, Sao Paulo. Identification of problems and their resolutions, the experience gained in plant operation, the performance characteristics of an ion-exchange facility and a solvent extraction unit (a demonstration plant based on pulsed columns for purification of uranium and production of ammonium diuranate) are described. A moving-bed facility for UF 4 preparation and its operation is discussed. A pilot plant for uranium and thorium oxide microsphere preparation based on internal gelation for HTGR fuel type is also described. A solvent extraction pilot plant for thorium purification based on a compound extraction-scrubbing column and a mixer-settler battery and the involved technology for thorium purification are commented. The main products, namely ammonium diuranate, uranyl amonium tricarbonate, uranium trioxide, uranium tetrafluoride, thorium nitrate and thorium oxalate and their quality are commented. The development of necessary analytical procedures for the quality control of the mentioned nuclear grade products is summarized. A great majority of such procedures was particularly suitable for analyzing traces impurities. Designed for installation are the units for denitration of uranyl nitrate solutions and pilot plants for elemental fluorine and UF 6 . The installation of a laboratory-scale plant designed for reprocessing irradiated uranium and an experimental unit for the recovery of protactinium from irradiated thorium is in progress

Spectrographic determination of zirconium, niobium, rhodium, ruthenium, tantalum, and tungsten in uranium and its compounds

International Nuclear Information System (INIS)

Alduan, F.A.; Capdevila, C.

1976-01-01

The determination of Nb, Rh, Ru, Ta, W and Zr in uranium and its compounds has been studied, using the carrier distillation method with either AgCl or AgCl-SrF 2 (4:3) as carrier. In order to get the best sensitivity, the influence of the carrier concentration, the dc arc intensity and several controlled atmospheres on the variation of the line to background ratio of intensities has been considered. With the most suitable conditions, the sensitivities achieved for the considered elements are in the range 1-10 ppm. (author)

Internal dosimetry and radiotoxicity of long-lived uranium isotopes

International Nuclear Information System (INIS)

Jacobi, W.

1980-03-01

The dose to relevant tissues and the effective dose equivalent by ingestion and inhalation of uranium compounds are evaluated on the basis of the new metabolic and dosimetric models recommended by ICRP. Applying these dose factors annual limits for intake of these compounds by workers are derived. Finally the natural uranium exposure of the population is described. From the measured natural U-content of body tissues dose factors for the dietary intake of uranium can be estimated. (orig.) [de

Chemical aspects of rubidium uranium sulphate for its use as a chemical standard for uranium

International Nuclear Information System (INIS)

Singh Mudher, K.D.; Khandekar, R.R.; Krishnan, K.; Jayadevan, N.C.; Sood, D.D.

1989-01-01

Rb 2 U(SO 4 ) 3 , a double sulphate of rubidium and uranium(IV) has been prepared and investigated for its use as a chemical standard for uranium. The compound can be easily prepared and crystallised in a pure form. The results of physico-chemical characterisation on preparation of 5-10 g. lots are described in this report. These studies suggest that the compound is anhydrous, stoichiometric, stable to atmospheric effects and easily soluble in acids and thus satisfies most of the criteria for a primary standard. (author). 13 refs., 4 figs., 6 tabs

U uranium. Suppl. Vol. D3

International Nuclear Information System (INIS)

Haug, H.O.

1982-01-01

This volume of the uranium series of the Gmelin handbook deals with the anion exchange of uranium. Compounds of the valence states of III, IV, V and VI of uranium in halide, nitrate, sulfate, phosphate, and carbonate media as well as in media containing organic complexing agents are treated. The literature cited covers the period from about 1947 to the end of 1980. (RB) [de

Identificación de prestaciones en nuevas aplicaciones de vidrio estructural

OpenAIRE

Abascal Capilla, Alba

2016-01-01

El presente Trabajo Fin de Grado consiste en la identificación de las prestaciones que se deben cumplir de cara al diseño de los elementos de vidrio estructural para aplicaciones actuales, novedosas e innovadoras. Para la identificación de las prestaciones se comienza por una evaluación del estado actual del vidrio; posteriormente se hace una selección de obras innovadoras en aplicaciones existentes con vidrio estructural (fachadas, cubiertas, barandillas, suelos, escaleras, pilares y viga...

Creación de un Framework de desarrollo de aplicaciones para la web con lenguaje PHP

OpenAIRE

Henríquez Chavarría, José Antonio

2013-01-01

El desarrollo de Frameworks, para desarrollo de aplicaciones en ambiente web, ha tenido un notable aumento, en los últimos años, debido a la necesidad de crear aplicaciones web y la urgencia de muchos por conseguir desarrollos con un ciclo de vida rápido, de forma que actualmente muchos desarrolladores de software requieren herramientas como un Framewok para lograr programar sus aplicaciones y dar seguimiento para siguientes versiones. El presente proyecto se plantea como una alternativa s...

Some peculiarities of the relationship between uranium and phosphate of nodular phosphorites of the Russian Platform

Energy Technology Data Exchange (ETDEWEB)

Kozlov, A A [Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Yadernoj Geofiziki i Geokhimii, Moscow (USSR)

1976-02-01

In nodular phosphorites of the Cenomanian stage of the central regions of the Russian platform the uranium content of phosphate ranges within 20 to 50x10/sup -4/%. The maximum concentrations of uranium are found in amorphous phosphates, the richest in humic colloid. Uranium found in the bone phosphate of fossil reptiles is uniformly distributed throughout the bone tissue area, its content amounting to 30 to 40x10/sup -4/%. As bone phosphate reaches its holocrystalline modification, the uranium compounds are substituted and the uranium concentration decreases to 0.2x10/sup -4/%, i.e. it becomes 200 times lower. The most intensive sorption of uranium by phosphate occurs under the reducing conditions of diagenesis which is characterized by the most comprehensive combination of uranium-sorption factors: the existence of various uranium compounds in solution, isomorphic substitutions of all kinds, adsorption of uranium compounds and organic matter on the surfaces of submicron crystalline phosphate compounds. A decrease in the intensity of sorption factors leads to a decrease in the uranium content of phosphate. Under the oxidative conditions prevailed during the formation of Khoperian silicophosphorites, uranium has been sorbed by the phosphate only in negligible amounts (0.1x10/sup -4/%) due to the lack of organic colloids and uranium compounds capable of isomorphic substitution.

Uranium (IV) carboxylates - I

Energy Technology Data Exchange (ETDEWEB)

Satpathy, K C; Patnaik, A K [Sambalpur Univ. (India). Dept. of Chemistry

1975-11-01

A few uranium(IV) carboxylates with monochloro and trichloro acetic acid, glycine, malic, citric, adipic, o-toluic, anthranilic and salicylic acids have been prepared by photolytic methods. The I.R. spectra of these compounds are recorded and basing on the spectral data, structure of the compounds have been suggested.

Titrimetric determination of uranium

International Nuclear Information System (INIS)

Florence, T.M.

1989-01-01

Titrimetric methods are almost invariably used for the high precision assay of uranium compounds, because gravimetric methods are nonselective, and not as reliable. Although precipitation titrations have been used, for example with cupferron and ferrocyanide, and chelate titrations with EDTA and oxine give reasonable results, in practice only redox titrations find routine use. With all redox titration methods for uranium a precision of 01 to 02 percent can be achieved, and precisions as high as 0.003 percent have been claimed for the more refined techniques. There are two types of redox titrations for uranium in common use. The first involves the direct titration of uranium (VI) to uranium (IV) with a standard solution of a strong reductant, such as chromous chloride or titanous chloride, and the second requires a preliminary reduction of uranium to the (IV) or (III) state, followed by titration back to the (VI) state with a standard oxidant. Both types of redox titrations are discussed. 4 figs

Crystal field effect in the uranium compounds - model calculations for CsUF6, Cs2UCl6 and UCl4

International Nuclear Information System (INIS)

Gajek, Z.; Mulak, J.

1987-01-01

A practical crystal field model allowing one to estimate the crystal field parameters from first principles is presented and applied to the actinide compounds. The model results directly from the renormalization (and reduction) procedure of the true Schroedinger equation for an effective Hamiltonian acting on the 5f spin-orbitals only. In practice this approach becomes convergent with the ab initio model of Newman. Three ionic uranium compounds: CsUF 6 , Cs 2 UCl 6 and UCl 4 have served as examples of the application. The results obtained, particularly for the first two compounds, are in good agreement with the experimental data. The contributions of different mechanisms responsible for the crystal field effect are discussed. (author)

Analytical method development and validation for quantification of uranium in compounds of the nuclear fuel cycle by Fourier Transform Infrared (FTIR) Spectroscopy

International Nuclear Information System (INIS)

Pereira, Elaine

2016-01-01

This work presents a low cost, simple and new methodology for direct quantification of uranium in compounds of the nuclear fuel cycle, based on Fourier Transform Infrared (FTIR) spectroscopy using KBr pressed discs technique. Uranium in different matrices were used to development and validation: UO 2 (NO 3 )2.2TBP complex (TBP uranyl nitrate complex) in organic phase and uranyl nitrate (UO 2 (NO 3 ) 2 ) in aqueous phase. The parameters used in the validation process were: linearity, selectivity, accuracy, limits of detection (LD) and quantitation (LQ), precision (repeatability and intermediate precision) and robustness. The method for uranium in organic phase (UO 2 (NO 3 )2.2TBP complex in hexane/embedded in KBr) was linear (r = 0.9980) over the range of 0.20% 2.85% U/ KBr disc, LD 0.02% and LQ 0.03%, accurate (recoveries were over 101.0%), robust and precise (RSD < 1.6%). The method for uranium aqueous phase (UO 2 (NO 3 ) 2 /embedded in KBr) was linear (r = 0.9900) over the range of 0.14% 1.29% U/KBr disc, LD 0.01% and LQ 0.02%, accurate (recoveries were over 99.4%), robust and precise (RSD < 1.6%). Some process samples were analyzed in FTIR and compared with gravimetric and X-ray fluorescence (XRF) analyses showing similar results in all three methods. The statistical tests (t-Student and Fischer) showed that the techniques are equivalent. The validated method can be successfully employed for routine quality control analysis for nuclear compounds. (author)

Acute and chronic toxicity of uranium compounds to Ceriodaphnia-Daphnia dubia

International Nuclear Information System (INIS)

Pickett, J.B.; Specht, W.L.; Keyes, J.L.

1993-01-01

A study to determine the acute and chronic toxicity of uranyl nitrate, hydrogen uranyl phosphate, and uranium dioxide to the organism Ceriodaphnia dubia was conducted. The toxicity tests were conducted by two independent environmental consulting laboratories. Part of the emphasis for this determination was based on concerns expressed by SCDHEC, which was concerned that a safety factor of 100 must be applied to the previous 1986 acute toxicity result of 0.22 mg/L for Daphnia pulex, This would have resulted in the LETF release limits being based on an instream concentration of 0.0022 mg/L uranium. The NPDES Permit renewal application to SCDHEC utilized the results of this study and recommended that the LETF release limit for uranium be based an instream concentration of 0.004 mg/L uranium. This is based on the fact that the uranium releases from the M-Area LETF will be in the hydrogen uranyl phosphate form, or a uranyl phosphate complex at the pH (6--10) of the Liquid Effluent Treatment Facility effluent stream, and at the pH of the receiving stream (5.5 to 7.0). Based on the chronic toxicity of hydrogen uranyl phosphate, a lower uranium concentration limit for the Liquid Effluent Treatment Facility outfall vs. the existing NPDES permit was recommended: The current NPDES permit ''Guideline'' for uranium at outfall M-004 is 0.500 mg/L average and 1.0 mg/L maximum, at a design flowrate of 60 gpm. It was recommended that the uranium concentration at the M-004 outfall be reduced to 0.28 mg/L average, and 0.56 mg/L, maximum, and to reduce the design flowrate to 30 gpm. The 0.28 mg/L concentration will provide an instream concentration of 0.004 mg/L uranium. The 0.28 mg/L concentration at M-004 is based on the combined flows from A-014, A-015, and A-011 outfalls (since 1985) of 1840 gpm (2.65 MGD) and was the flow rate which was utilized in the 1988 NPDES permit renewal application

Yellowcake processing in uranium recovery

International Nuclear Information System (INIS)

Paul, J.M.

1981-01-01

This information relates to the recovery of uranium from uranium peroxide yellowcake produced by precipitation with hydrogen peroxide. The yellowcake is calcined at an elevated temperature to effect decomposition of the yellowcake to uranium oxide with the attendant evolution of free oxygen. The calcination step is carried out in the presence of a reducing agent which reacts with the free oxygen, thus retarding the evolution of chlorine gas from sodium chloride in the yellowcake. Suitable reducing agents include ammonia producing compounds such as ammonium carbonate and ammonium bicarbonate. Ammonium carbonate and/or ammonium bicarbonate may be provided in the eluant used to desorb the uranium from an ion exchange column

Yellowcake processing in uranium recovery

Energy Technology Data Exchange (ETDEWEB)

Paul, J.M.

1981-10-06

This information relates to the recovery of uranium from uranium peroxide yellowcake produced by precipitation with hydrogen peroxide. The yellowcake is calcined at an elevated temperature to effect decomposition of the yellowcake to uranium oxide with the attendant evolution of free oxygen. The calcination step is carried out in the presence of a reducing agent which reacts with the free oxygen, thus retarding the evolution of chlorine gas from sodium chloride in the yellowcake. Suitable reducing agents include ammonia producing compounds such as ammonium carbonate and ammonium bicarbonate. Ammonium carbonate and/or ammonium bicarbonate may be provided in the eluant used to desorb the uranium from an ion exchange column.

Some potential strategies for the treatment of waste uranium metal and uranium alloys

International Nuclear Information System (INIS)

Burns, C.J.; Frankcom, T.M.; Gordon, P.L.; Sauer, N.N.

1993-01-01

Large quantities of uranium metal chips and turnings stored throughout the DOE Complex represent a potential hazard, due to the reactivity of this material toward air and water. Methods are being sought to mitigate this by conversion of the metal, via room temperature solutions routes, to a more inert oxide form. In addition, the recycling of uranium and concomitant recovery of alloying metals is a desirable goal. The emphasis of the authors' research is to explore a variety of oxidation and reduction pathways for uranium and its compounds, and to investigate how these reactions might be applied to the treatment of bulk wastes

Measurement methods and optimization of radiation protection: the case of internal exposure by inhalation to natural uranium compounds

International Nuclear Information System (INIS)

Degrange, J.P.; Gibert, B.

1998-01-01

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.)

Resinas acetálicas: diversas aplicaciones en odontoestomatología

OpenAIRE

Puigpelat Martí, Ana M.; Casanellas Bassols, Josep M. (Josep Maria)

1994-01-01

La resina acetálica o Polioxime­tileno (POM) es un nuevo material estético de reciente aplicación en el campo de la Odontoestomatolo­gía. En este artículo presentamos al­gunas de las aplicaciones donde la estética desempeña una función importante. Una de las aplicaciones de las re­sinas acetálicas es el campo de la Prótesis Parcial Removible, cuan­do queremos sustituir los retene­dores vestibulares convencionales (metálicos) por retenedores más es­téticos. Otra posible aplicación puede ser la...

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

International Nuclear Information System (INIS)

Rabinowitch, E. I.; Katz, J. J.

1946-01-01

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.

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)

Determination of metallic impurities in nuclearly pure uranium compounds by electrothermal spectrophotometry

International Nuclear Information System (INIS)

Franco, M.B.

1986-01-01

Atomic absorption spectrometry, with electrothermal atomization, has been used for the determination of Al, Cd, Cr, Fe, Mn and Ni in uranium oxide standards. The analysis were performed without sample dissolution and without uranium chemical separation. This technique is adequate for the qualification of nuclearly pure uranium, according to the standard specifications. (Author) [pt

Uranium chemistry research unit

International Nuclear Information System (INIS)

Anon.

1978-01-01

The initial field of research of this Unit, established in 1973, was the basic co-ordination chemistry of uranium, thorium, copper, cobalt and nickel. Subsequently the interest of the Unit extended to extractive metallurgy relating to these metals. Under the term 'co-ordination chemistry' is understood the interaction of the central transition metal ion with surrounding atoms in its immediate vicinity (within bonding distance) and the influence they have on each other - for example, structural studies for determining the number and arrangement of co-ordinated atoms and spectrophotometric studies to establish how the f electron energy levels of uranium are influenced by the environment. New types of uranium compounds have been synthesized and studied, and the behaviour of uranium ions in non-aqueous systems has also received attention. This work can be applied to the development and study of extractants and new extractive processes for uranium

Microporous Silico-Alumino Phosphate (SAPO) Compound For Uranium Sorption

International Nuclear Information System (INIS)

Siti-Amini

1998-01-01

The zeotype novel materials I.e. SAPO structures have been prepared to have particular property such as sorption or cations exchanger which can accommodate the uranyl ions. The SAPO's model was built from certain mole ratio of SiO 2 +AIO 2 +PO 2 using various template compounds of tetra(alkyl)s aminium hydroxide viz. Tetra-methyl, tetra-ethyl and tetra-propyl aminium. Those formed materials have been analyzed using x-ray diffraction spectrometer , then the data have been complied using the supporting software videozeo package Ver.3.1. The result have shown that crystalline structures of microporous SAPO materials formed are SAPO-20, SAPO-34, and SAPO-40. The exchanger capacities of some zeolites, SAPOs and ASP(1:3) have been studied and their selectivity to uranyl ions in acid solution (ph<3.5) has been determined by static isotherm exchanger process. The result have revealed various selectivity factors and occurrence of absorption mechanism in SAPO-n materials. This promises that uranium separation could be more effective using SAPO-n than that using other zeolites . The chloride ions have slightly decreased the ion-exchange capacity, while that of fluoride ions increased the ion-exchange capacity of ASP(1:3) for the uranyl ions

Kazakhstan uranium industry: towards the XXI century with clean technologies

International Nuclear Information System (INIS)

Dzhakishev, M.E.; Yazikov, V.G.; Dujsebaev, B.O.; Zabaznov, V.L.

2001-01-01

Kazakhstan is a leading country of the world by uranium resources, and in the it Earth's interior 19 % of world proved resources are concentrated. At present the National Atomic Company (NAC) Kazatomprom is responsible for uranium mining and production of natural uranium and its compounds in the Republic. The company activity covers the exploring, mining and export of natural uranium; production of slightly enriched uranium compounds and fuel pellets production for nuclear reactors. In the company there are three Uranium Ore Mining Departments in the South Kazakhstan, VolgovGeology Geological Exploration Enterprise and Ulba Metallurgical Plant. Mining is carrying out by technologically progressive ecologically clean technology of in-situ well leaching. The key importance the company pays to environment protection activities. NAC Kazatomprom sees perspectives of Kazakhstan uranium industry in formation of general all-sufficient technological cycle from uranium mining to fuel supply on the nuclear plants. The missing links - enrichment by U-235 isotope and fuel assemblies production - should be replaces by formation of steady partnership cooperation with foreign enterprises

Enthalpies of vaporization of organometallic compounds

International Nuclear Information System (INIS)

Kuznetsov, N.T.; Sevast'yanov, V.G.; Mitin, V.A.; Krasnodubskaya, S.V.; Zakharov, L.N.; Domrachev, G.A.; AN SSSR, Gor'kij. Inst. Khimii)

1987-01-01

A possibility to use the method of additive schemes for the calculation of vaporizaton enthalpies of uranium organometallic compounds is discussed while comparing the values obtained using the method with experimental data. The possibility of apriori evaluation of evaporation enthalpy values of different uranium compounds using the method of additive schemes and structural characteristics of molecules, such as the sum of ligand solid angles, is shown

Uranium from seawater

International Nuclear Information System (INIS)

Gregg, D.; Folkendt, M.

1982-01-01

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 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 3 in seawater instead of the reported values of 10 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 5 in fresh water. However, the system was not tested in seawater

Neurofeedback, aplicaciones y eficacia

OpenAIRE

Fajardo, Alexandra; Guzmán, Ana Lucía

2016-01-01

El objetivo del estudio que se informa fue describir la técnica de neurofeedback, sus aplicaciones y usos, como así también determinar su eficacia a lo largo de los estudios revisados. De esta forma se encuentra la compilación de 53 artículos científicos acerca de la técnica, que describen cómo los autores han demostrado su funcionalidad, cuando se trata de proyectar de manera tangible el rendimiento de algún tipo de población para la posterior formulación de un tratamiento o intervención par...

Structure of some complex halides of uranium(III)

International Nuclear Information System (INIS)

Volkov, V.A.; Suglobova, I.G.; Chirkst, D.E.

1987-01-01

Polycrystals of some halide complexes of uranium(III) were obtained and investigated by x-ray diffraction. The M 2 UCl 5 compounds (M = K, Rb) are isostructural with K 2 PrCl 5 ; RbU 2 Cl 7 is of the same type as RbDy 2 Cl 7 or KDy 2 Cl 7 . The coordination number of the uranium is 7. The M 2 UBr 5 compounds (M = K-Cs) are isostructural with Cs 2 DyCl 5 , and the coordination number of the uranium is 6. Rb 2 NaUCl 6 is a 12L-hexagonal polytype, the structural analog of Cs 2 NaCrF 6 . The most characteristic coordination number of uranium in the UHal 3 -MHal systems is 8 for Hal = F, 7 for Hal = Cl, and 6 for Hal = Br

Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid

International Nuclear Information System (INIS)

Sung, J.; Kim, J.; Lee, Y.; Seol, J.; Ryu, J.; Park, K.

2011-01-01

The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 deg. C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined. (authors)

Crystal growth of uranium compounds and study of UGe2

International Nuclear Information System (INIS)

Taufour, V.

2011-01-01

In this thesis, the study on the superconducting ferromagnet UGe 2 is presented. Crystal growth of UGe 2 single crystals was realized in a tetra-arc furnace using the Czochralski technique. This technique was also used to obtain high quality single crystals of other uranium compounds, notably UCoGe and URu 2 Si 2 . The Curie temperature of UGe 2 (T(Curie) = 53 K) decreases with pressure and is suppressed at p c = 1.5 GPa. Before being suppressed, the ferromagnetic transition changes from second to first order at a tricritical point. Precise resistivity and Hall resistivity measurements under pressure and magnetic field revealed the position of the tricritical point as well as its evolution under magnetic field which draw a wing structure phase diagram. Despite the theoretical prediction that this diagram is general for a ferromagnet, here we present the first experimental observation. Other measurements focus on the superconductivity (T sc = 0.75 K) which coexists with ferromagnetism under pressure. The bulk nature of the superconductivity is investigated by AC calorimetry measurements under pressure. The attention is turned to the interesting phenomenon of field enhanced superconductivity. (author) [fr

Sistema para la monitorización y estudio de aplicaciones maliciosas para Android

OpenAIRE

Gutiérrez Hernández, Sergio

2014-01-01

Los teléfonos móviles inteligentes (smartphones) se han posicionado como aparatos altamente populares con grandes capacidades de cómputo, comunicación y sensorización. Estos dispositivos se caracterizan por su habilidad para incorporar aplicaciones desarrolladas por terceras partes, capaces de acceder a los servicios proporcionados por el smartphone. En este contexto, hemos podido observar durante los últimos años un crecimiento exponencial en el número de muestras de aplicaciones haciendo un...

Recovering phosphorus and uranium values from phosphate rock

International Nuclear Information System (INIS)

Sze, M.C.Y.; Long, R.H.

1981-01-01

Phosphate rock is acidulated with aqueous nitric acid to produce an aqueous solution containing phosphate values, calcium and uranium values. The aqueous solution is contacted with an extraction solvent for the uranium values: the extraction solvent comprising a water immiscible organic diluent, a dialkyl phosphoric acid having at least 10 carbon atoms, and an organic phosphorus compound having the formula R 1 R 2 R 3 P = O where R 1 , R 2 and R 3 are each either alkyl or alkoxy, the organic phosphorus compound having at least 10 carbon atoms. The uranium values are then recovered from the extraction solvent. In an example the extraction solvent is HDEHP and TOPO in kerosene. (author)

Purification of the Drain Water and Distillation Residues from Organic Compounds, Transuranic Elements and Uranium at the Chernobyl NPP

Directory of Open Access Journals (Sweden)

Rudenko, L.I.

2014-05-01

Full Text Available Article examines the purification of drain water and distillation residue from organic (polymeric compounds, tran suranic elements and uranium. We propose the pretreatment method with the use of a type «Sizol» coagulant-flocculant and catalytic oxidation with hydrogen peroxide and ultrafiltration. This method prevents evaporator coking by dustsuppression and other organic substances, which are vulcanized by heating. Removing alpha-emitting radionuclides increases safety level at the nuclear power plant.

Study of internal exposure to uranium compounds in fuel fabrication plants in Brazil; Estudo da exposicao interna a compostos de uranio na fabricacao do elemento combustivel nuclear no Brasil

Energy Technology Data Exchange (ETDEWEB)

Santos, Maristela Souza

2006-07-01

The International Commission on Radiological Protection (ICRP) Publication 66 and Supporting Guidance 3) strongly recommends that specific information on lung retention parameters should be used in preference to default values wherever appropriate, for the derivation of effective doses and for bioassay interpretation of monitoring data. A group of 81 workers exposed to UO{sub 2} at the fuel fabrication facility in Brazil was selected to evaluate the committed effective dose. The workers were monitored for determination of uranium content in the urinary and faecal excretion. The contribution of intakes by ingestion and inhalation were assessed on the basis of the ratios of urinary to fecal excretion. For the selected workers it was concluded that inhalation dominated intake. According to ICRP 66, uranium oxide is classified as insoluble Type S compound. The ICRP Supporting Guidance 3 and some recent studies have recommended specific lung retention parameters to UO{sub 2}. The solubility parameters of the uranium oxide compound handled by the workers at the fuel fabrication facility in Brazil was evaluated on the basis of the ratios of urinary to fecal excretion. Excretion data were corrected for dietary intakes. This paper will discuss the application of lung retention parameters recommended by the ICRP models to these data and also the dependence of the effective committed dose on the lung retention parameters. It will also discuss the problems in the interpretation of monitoring results, when the worker is exposed to several uranium compounds of different solubilities. (author)

Bioremediation of uranium contaminated Fernald soils

International Nuclear Information System (INIS)

Delwiche, M.E.; Wey, J.E.; Torma, A.E.

1994-01-01

This study investigated the use of microbial bioleaching for removal of uranium from contaminated soils. The ability of bacteria to assist in oxidation and solubilization of uranium was compared to the ability of fungi to produce complexing compounds which have the same effect. Biosorption of uranium by fungi was also measured. Soil samples were examined for changes in mineralogical properties due to these processes. On the basis of these laboratory scale studies a generalized flow sheet is proposed for bioremediation of contaminated Fernald soils

Phosphorus and uranium recovery process from phosphated rocks

Energy Technology Data Exchange (ETDEWEB)

Sze, M C.Y.; Long, R H

1981-01-30

Improvement of uranium recovery in phosphate rocks by treatment with nitric acid avoiding the formation of a precipitate including a part of the uranium. The separation of uranium from phosphoric acid is obtained by liquid-liquid extraction using dialkyl posphoric acid with at least 10 carbon atoms and a phosphoryl alkyl alkoxy compound with at least 10 carbon atoms and a non water miscible organic solvent.

Extraction photometric determination of uranium (6) with use of malachite green

International Nuclear Information System (INIS)

Stepanenko, Yu.V.; Bagdasarov, K.N.; Shchemeleva, G.G.

1975-01-01

A study of the reaction between uranium (6) and malachite green in the presence of sodium benzoate has indicated that, in a weakly acid medium (pH 4.5 to 5.5), the reaction yields a poorly soluble greenish compound which tends to be extracted by a 1-to-1 mixture of benzene and chloroform. The compound comprises uranium, a benzoate and a malachite green in a ratio of 1/3/1. A method has been developed for an extraction-photometric determination of uranium in metallic lead

Extraction photometric determination of uranium (6) with use of malachite green

Energy Technology Data Exchange (ETDEWEB)

Stepanenko, Yu V; Bagdasarov, K N; Shchemeleva, G G [Rostovskij-na-Donu Gosudarstvennyj Univ. (USSR)

1975-12-01

A study of the reaction between uranium (6) and malachite green in the presence of sodium benzoate has indicated that, in a weakly acid medium (pH 4.5 to 5.5), the reaction yields a poorly soluble greenish compound which tends to be extracted by a 1-to-1 mixture of benzene and chloroform. The compound comprises uranium, a benzoate and a malachite green in a ratio of 1/3/1. A method has been developed for an extraction-photometric determination of uranium in metallic lead.

Análisis de la calidad y seguridad de la información de aplicaciones móviles en prevención terciaria

Directory of Open Access Journals (Sweden)

Martínez-Moreno J

2015-12-01

Full Text Available Objetivo: Analizar la calidad y seguridad de la información de las aplicaciones móviles en la App Store de Apple® destinadas a prevención terciaria. Material y métodos: Estudio observacional transversal de las aplicaciones móviles más populares en la categoría de medicina disponibles en Apple Store® a día de 21 de diciembre de 2014. Las aplicaciones fueron evaluadas con los criterios establecidos en el programa AppSaludable. Se seleccionaron aquellos criterios relacionados con la evaluación de la calidad y seguridad de la información. Resultados: De las 160 aplicaciones recogidas, sólo 12 aplicaciones estaban incluidas en la prevención terciaria. Todas las aplicaciones recuperadas estaban relacionadas con la adherencia, diabetes, hipertensión y alergia. Las aplicaciones desarrolladas por equipos multidisciplinares fueron las que presentaron mayor rigor en su información, Conclusiones: La presencia de un profesional sanitario como colaborador de la aplicación parece mejorar la calidad de la información.

Recovery or removal of uranium contained in small quantity in waste water by tannic-group adsorbent

Energy Technology Data Exchange (ETDEWEB)

Komoto, Shigetoshi [Power Reactor and Nuclear Fuel Development Corp., Kamisaibara, Okayama (Japan). Ningyo Toge Works

1991-12-01

It was found that tannic compounds have a very strong affinity for uranium and thorium which are nuclear fuel materials, and the new uranium adsorbents composed mainly by tannic-group compounds were made. The solid-state refractory persimmon tannins in those compounds has the most superior capacity for uranium as high as 1.7 g of uranium on 1 g of the adsorbent. The tests adsorbing uranium on the adsorbent are carried out practically by using dam water of Ningyo-toge Works, PNC. Adsorption tests changed the pH or temperature of dam water, elution test, and adsorption-elution repeating test were performed, and it was found that uranium in dam water contained from ppb-level to ppm-level was recovered or removed with very excellent efficiency. (author).

The role of uranium-arene bonding in H2O reduction catalysis

Science.gov (United States)

Halter, Dominik P.; Heinemann, Frank W.; Maron, Laurent; Meyer, Karsten

2018-03-01

The reactivity of uranium compounds towards small molecules typically occurs through stoichiometric rather than catalytic processes. Examples of uranium catalysts reacting with water are particularly scarce, because stable uranyl groups form that preclude the recovery of the uranium compound. Recently, however, an arene-anchored, electron-rich uranium complex has been shown to facilitate the electrocatalytic formation of H2 from H2O. Here, we present the precise role of uranium-arene δ bonding in intermediates of the catalytic cycle, as well as details of the atypical two-electron oxidative addition of H2O to the trivalent uranium catalyst. Both aspects were explored by synthesizing mid- and high-valent uranium-oxo intermediates and by performing comparative studies with a structurally related complex that cannot engage in δ bonding. The redox activity of the arene anchor and a covalent δ-bonding interaction with the uranium ion during H2 formation were supported by density functional theory analysis. Detailed insight into this catalytic system may inspire the design of ligands for new uranium catalysts.

Metabolism and toxicology of the uranium compounds

International Nuclear Information System (INIS)

Salomon, A.P.

1976-01-01

Three important points to be considered in the metabolic behaviour of uranium are: 1) ionic behaviour which depends only on its chemical characteristics; 2) behaves in the organism as a unique element and has no metabolism similar to others like for example Sr-90 and Ba-140 which are akin to Ca; and 3) metabolism is identical for the three isotopes of uranium and has no isotopic effect. The metabolic decomposition undergoes three phases namely: 1) absorption of the components up to the blood streams; 2) distribution through the blood into the organs; and 3) elimination. The mode of entry in the organism is through inhalation, ingestion, wounds, absorption through the skin, and entry by the eyes. Uranium decomposes in the blood after its entry, disperses in the extracellular medium and deposits in the different organs of the body. However, it has no definite fixation and the different compartments are always in equilibrium with each other. Elimination of contamination is through the feces and urine. In case of massive absorption, that is either acute or sub-acute toxicity, the following are the subsequent effects: a) clinical effects major lesion in the kidneys whatever the mode of entry may be and feebleness of the muscles, apathy and nausea are noted; b) lesions in the renal region-yellowish gray in the medular and critical region; c) biological effects-appearance of proteinuria and catalysuria, cellular wastes in the urine and a change in the capacity to reabsorb Na + , Cl - , and glucose. The lethal dose is 1 mg U-nat/kg.wt. The dose provoking renal lesion is 0.1mg U/kg.wt. The maximum permissible dose is: a) annual dose 40 mg U-nat/yr; b) Inhalation 2.5 mg/day; c) Ingestion 150 mg/2 days consecutive (soluble = 4.7x10 -1 μCi, insoluble = 3.4x10 -2 μCi

Recovering phosphorus and uranium values from phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Sze, M C.Y.; Long, R H

1981-02-11

Phosphate rock is acidulated with aqueous nitric acid to produce an aqueous solution containing phosphate values, calcium and uranium values. The aqueous solution is contacted with an extraction solvent for the uranium values: the extraction solvent comprising a water immiscible organic diluent, a dialkyl phosphoric acid having at least 10 carbon atoms, and an organic phosphorus compound having the formula R/sub 1/ R/sub 2/ R/sub 3/ P = O where R/sub 1/, R/sub 2/ and R/sub 3/ are each either alkyl or alkoxy, the organic phosphorus compound having at least 10 carbon atoms. The uranium values are then recovered from the extraction solvent. In an example the extraction solvent is HDEHP and TOPO in kerosene.

A mononuclear uranium(IV) single-molecule magnet with an azobenzene radical ligand

Energy Technology Data Exchange (ETDEWEB)

Antunes, Maria A.; Coutinho, Joana T.; Santos, Isabel C.; Marcalo, Joaquim; Almeida, Manuel; Pereira, Laura C.J. [C" 2TN, Instituto Superior Tecnico, Universidade de Lisboa, Bobadela (Portugal); Baldovi, Jose J.; Gaita-Arino, Alejandro; Coronado, Eugenio [Instituto de Ciencia Molecular, Universitat de Valencia, Paterna (Spain)

2015-12-01

A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe_2NPh)_3-tacn}U{sup IV}(η{sup 2}-N{sub 2}Ph{sub 2{sup .}})] (2), was obtained by one-electron reduction of azobenzene by the trivalent uranium compound [U{sup III}{(SiMe_2NPh)_3-tacn}] (1). Compound 2 was characterized by single-crystal X-ray diffraction and {sup 1}H NMR, IR, and UV/Vis/NIR spectroscopy. The magnetic properties of 2 and precursor 1 were studied by static magnetization and ac susceptibility measurements, which for the former revealed single-molecule magnet behaviour for the first time in a mononuclear U{sup IV} compound, whereas trivalent uranium compound 1 does not exhibit slow relaxation of the magnetization at low temperatures. A first approximation to the magnetic behaviour of these compounds was attempted by combining an effective electrostatic model with a phenomenological approach using the full single-ion Hamiltonian. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

International Nuclear Information System (INIS)

Haas, P.A.

1992-02-01

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

Ingeniería de software en el desarrollo de aplicaciones para dispositivos móviles

OpenAIRE

Thomas, Pablo Javier; Galdámez, Nicolás; Delía, Lisandro Nahuel; Cristina, Federico; Dapoto, Sebastián H.; Tinetti, Fernando Gustavo; Pesado, Patricia Mabel; De Giusti, Armando Eduardo

2013-01-01

Se presenta una línea de investigación y desarrollo que tiene por objeto estudiar temas relacionados con aplicaciones para dispositivos móviles, fundamentalmente aspectos de Ingeniería de Software orientados al desarrollo e implementación de aplicaciones móviles, sobre diversos entornos operativos y el estudio y desarrollo de aspectos de conectividad entre dispositivos móviles.

Phosphate Barriers for Immobilization of Uranium Plumes

International Nuclear Information System (INIS)

Burns, Peter C.

2004-01-01

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

Phosphate Barriers for Immobilization of Uranium Plumes

International Nuclear Information System (INIS)

Icenhower, Jonathan P.; Burns, Peter C.

2005-01-01

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

Bioremediation of ground water contaminants at a uranium mill tailings site

International Nuclear Information System (INIS)

Barton, L.L.; Nuttall, H.E.; Thomson, B.M.; Lutze, W.

1995-01-01

Ground water contaminated with uranium from milling operations must be remediated to reduce the migration of soluble toxic compounds. At the mill tailings site near Tuba City, Arizona (USA) the approach is to employ bioremediation for in situ immobilization of uranium by bacterial reduction of uranyl, U(VI), compounds to uraninite, U(IV). In this initial phase of remediation, details are provided to indicate the magnitude of the contamination problem and to present preliminary evidence supporting the proposition that bacterial immobilization of uranium is possible. Additionally, consideration is given to contaminating cations and anions that may be at toxic levels in ground water at this uranium mill tailing site and detoxification strategies using bacteria are addressed. A model concept is employed so that results obtained at the Tuba City site could contribute to bioremediation of ground water at other uranium mill tailings sites

Aplicaciones científicas numéricas: El (ciclo de vida del) Software heredado

OpenAIRE

Méndez, Mariano; Tinetti, Fernando Gustavo

2012-01-01

El objetivo de esta línea de investigación es el estudio de las aplicaciones científicas de cómputo numérico desde el punto de vista de la Ingeniería de Software y del Procesamiento Paralelo. Además, se orienta a desarrollar técnicas y herramientas destinadas a reestructurar dichas aplicaciones permitiendo que éstas evolucionen a través del tiempo mejorando sus prestaciones y su estructura.

Debye temperatures of uranium chalcogenides from their lattice ...

Indian Academy of Sciences (India)

Phonon dispersion relations in uranium chalcogenides have been investigated using a modified three-body force shell model. From the phonon frequencies, their Debye temperatures are evaluated. Further, on the basis of the spin fluctuation in the heavy fermion uranium compounds, UPt3 and UBe13, the possible ...

Diseño de una arquitectura para redes de sensores con soporte para aplicaciones de detección de eventos

OpenAIRE

LINO RAMIREZ, CARLOS

2012-01-01

Las aplicaciones para redes de sensores inalámbricas, o Wireless Sensor Networks (WSNs), han mostrado un crecimiento significativo en los últimos años. Actualmente constituyen una alternativa tecnológica interesante para el desarrollo de aplicaciones que requieren monitorizar constantemente el estado de cualquier variable relacionada con escenarios de diversos ámbitos. Si las aplicaciones detectan cambios en los valores de dichas variables, pueden activar la ejecución de acciones preventivas ...

Standard test method for the analysis of refrigerant 114, plus other carbon-containing and fluorine-containing compounds in uranium hexafluoride via fourier-transform infrared (FTIR) spectroscopy

CERN Document Server

American Society for Testing and Materials. Philadelphia

2004-01-01

1.1 This test method covers determining the concentrations of refrigerant-114, other carbon-containing and fluorine-containing compounds, hydrocarbons, and partially or completely substituted halohydrocarbons that may be impurities in uranium hexafluoride. The two options are outlined for this test method. They are designated as Part A and Part B. 1.1.1 To provide instructions for performing Fourier-Transform Infrared (FTIR) spectroscopic analysis for the possible presence of Refrigerant-114 impurity in a gaseous sample of uranium hexafluoride, collected in a "2S" container or equivalent at room temperature. The all gas procedure applies to the analysis of possible Refrigerant-114 impurity in uranium hexafluoride, and to the gas manifold system used for FTIR applications. The pressure and temperatures must be controlled to maintain a gaseous sample. The concentration units are in mole percent. This is Part A. 1.2 Part B involves a high pressure liquid sample of uranium hexafluoride. This method can be appli...

Estimation of uranium forms in oceanic water

International Nuclear Information System (INIS)

Krylov, O.T.; Novikov, P.D.; Nesterova, M.P.

1985-01-01

A critical consideration is given to the notions about uranium forms in ocean water. To estimate uranium forms a model is suggested which takes into account possjble formation of complexes of uranyl ions and ocean water anions Cl - , SO 4 2- , CO 3 2- , HCO 3 - , OH - , F - . The available published data are used to estimate necessary thermodynamic stability constants of the complexes, activity coefficients and concentration of componenets. The thermodynamic calculation shows that uranium hydroxocomplex compounds UO 2 (OH) 4 2- (99.17%) and UO 2 (OH) 3 - (083%) are the most probable uranium forms in ocear water of 34.3% salinity at 25 deg C and 1 atm pressure

Model of the coercion uranium hexafluoride on a human body

International Nuclear Information System (INIS)

Babenko, S.P.

2007-01-01

A method for calculating certain quantities characterizing the effect of uranium hexafluoride (UF 6 ) on the human body under industrial conditions in uranium enrichment plants is described. It is assumed that the effect is determined by uranium and fluorine inhaled together with the products of hydrolysis of uranium hexafluoride. The proposed complex model consists of three models, the first of which describes the contamination of the industrial environment and the second and third describe inhalation and percutaneous intake. A relation is obtained between uranium and fluorine intake and the uranium hexafluoride concentration in air at the moment the compound is discharged [ru

Epidemiological study of workers at risk of internal exposure to uranium

International Nuclear Information System (INIS)

Guseva Canu, I.

2008-09-01

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

Sistemas ubiquos: desarrollo y aplicaciones

OpenAIRE

Ramón, Hugo Dionisio; Charne, Javier; Di Cicco, Carlos; Riva, Diego Germán de la; Smail, Ana; Osella Massa, Germán Leandro

2013-01-01

Se presenta un proyecto de investigación aplicada al cómputo ubiquo (ubicomp), abarcando aspectos que van desde los fundamentos del desarrollo (técnicas de Ingeniería de requerimientos, metodologías de gestión, desarrollo de proyectos, técnicas de planificación, métricas, normas de calidad, redes de sensores y algoritmos inteligentes y procesamiento de señales) hasta la concepción de aplicaciones específicas orientadas a los procesos productivos de la región y el país, procesos de egobierno y...

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

Energy Technology Data Exchange (ETDEWEB)

Haas, P.A.

1992-02-01

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

Spectrographic determination of boron and silicon in uranium tetrafluoride: Study of the chemical reactions in the electrode cavity when ZnO is used as a uranium excitation suppressor

International Nuclear Information System (INIS)

Alduan, F. A.; Capdevila, C.; Roca, M.

1973-01-01

A method has been developed for determining traces of boron and silicon in uranium tetrafluoride. Use is made of zinc oxide to decrease the volatilization of uranium and achieve high sensitivities. The thermochemical reactions which occur in the anode cavity during the arcing process have been investigated. UO 2 and a uranium, zinc and fluorine compound, both less volatile than uranium tetrafluoride, are formed. (Author)

Technology for down-blending weapons grade uranium into commercial reactor-usable uranium

International Nuclear Information System (INIS)

Arbital, J.G.; Snider, J.D.

1996-01-01

The US Department of Energy (DOE) is evaluating options for rendering surplus inventories of highly enriched uranium (HEU) incapable of being used in nuclear weapons. Weapons-capable HEU was earlier produced by enriching the uranium isotope 235 U from its natural occurring 0.71 percent isotopic concentration to at least 20 percent isotopic concentration. Now, by permanently diluting the concentration of the 235 U isotope, the weapons capability of HEU can be eliminated in a manner that is reversible only through isotope re-enrichment, and therefore, highly resistant to proliferation. To the extent that can be economically and technically justified, the down-blended, low-enriched uranium product will be made suitable for use as commercial reactor fuel. Such down-blended uranium product can also be disposed of as waste if chemical or isotopic impurities preclude its use as reactor fuel. The DOE has evaluated three candidate processes for down blending surplus HEU. These candidate processes are: (1) uranium hexafluoride blending; (2) molten uranium metal blending; and (3) uranyl nitrate solution blending. This paper describes each of these candidate processes. It also compares the relative advantages and disadvantages of each process with respect to: (1) the various forms and compounds of HEU comprising the surplus inventory, (2) the use of down-blended product as commercial reactor fuel, or (3) its disposal as waste

Uranium-oxide-based catalysts for the destruction of volatile chloro-organic compounds

International Nuclear Information System (INIS)

Hutchings, G.; Heneghan, C.S.; Taylor, S.H.

1996-01-01

The industrial release of hydrocarbons and chlorine-containing organic molecules into the environment continues to attract considerable public concern, which in turn has led to governmental attempts to control such emissions. The challenge is to reduce pollution without stifling economic growth. Chlorine-containing pollutants are known to be particularly stable, and at present the main industrial process for their destruction involves thermal oxidation at 1,000 o C, an expensive process that can lead to the formation of highly toxic by-products such as dioxins and dibenzofurans. Catalytic combustion at lower temperatures could potentially destroy pollutants more efficiently (in terms of energy requirements) and without forming toxic by-products. Current industrial catalysts are based on precious metals that are deactivated rapidly by organochlorine compounds. Here we report that catalysts based on uranium oxide efficiently destroy a range of hydrocarbon and chlorine-containing pollutants, and that these catalysts are resistant to deactivation. We show that benzene, toluene, chlorobutane and chlorobenzene can be destroyed at moderate temperatures ( o C) and industrially relevant flow rates. (Author)

Preparation of uranium coatings by electro deposition in molten chloride media

International Nuclear Information System (INIS)

Taxil, P.; Serrano, K.; Dugne, O.

2001-01-01

The electrodeposition of uranium is now a relevant topic for two kinds of applications: the preparation of this metal with compounds extracted from the mineral ores; the separation from lanthanides in the nuclear waste. This paper concerns the process of preparation of uranium metal on various substrates, using the electro deposition process in molten salts. The electrolyte consists of an eutectic mixture NaCl-KCl as solvent (fusion point 650 deg C) and a tetravalent uranium compound, UCl 4 as solute. We present the results, theoretical and practical, necessary to manage the process. So, the following points will be considered stepwise in this paper: the electrochemical behaviour of uranium III ions in the electrolyte, since it is now clearly established that uranium metal can be prepared by electrochemical reduction of UCl 3 in a NaCl-KCl mixture in a single step process: U III + 3 e → U 0 ; the crystallisation mode of uranium on the cathodic material; the preparation of uranium coatings with variables conditions: temperature, electrolyte concentration, current density and cathodic substrate; the observation of the crystal growth on the substrates, by using SEM micrographies. (authors)

Uranium determination in different compositions

International Nuclear Information System (INIS)

Bulyanitsa, L.S.; Ivanova, K.S.; Ryzhinskij, M.V.; Alekseeva, N.A.; Solntseva, L.F.; Shereshevskaya, I.I.

1978-01-01

For clarifying the suitability of two different methods of analysis for determining uranium without its previous purification, the analysis of uranium carbides (UC, UC 2 , UC - ZrC) and alloys (U - Al, U - Zr - Nb, U- Ti) has been carried out. Dissolution of the compositions examined was carried out either after previous calcining (UC, UC 2 ) or fusion with KHSO 4 (UC - ZrC), or in phosphoric acid (alloys). The first method, a variant of potentiometric titration, has been modified for small amounts of uranium. Titration was carried out on a semiautomatic titrating unit. The uranium amount per titration is about 4 to 5 mg. The second method of analysis is the coulombmetric titration at a constant current intensity. The quantity of uranium per titration was equal to 1 - 3 mg. The statistical processing of the results obtained was carried out by a dispersion analysis that allowed to reveal the influence of separate factors, such as method of analysis, type of composition, the non-uniformity of a sample, the enumerated factors influencing the dispersion of the analysis results. It has been shown that the both methods are equally suitable for analysis of the uranium compounds examined

Electrochemical investigation of uranium β-diketonates for all-uranium redox flow battery

International Nuclear Information System (INIS)

Yamamura, Tomoo; Shiokawa, Yoshinobu; Yamana, Hajimu; Moriyama, Hirotake

2002-01-01

The redox flow battery using uranium as the negative and the positive active materials in polar aprotic solvents was proposed. In order to establish the guiding principle for the uranium compounds as the active materials, the investigation of uranium β-diketonate complexes was conducted on (i) the solubility of active materials, (ii) the electrode reaction of U(VI) and U(IV) β-diketonate complexes and (iii) the estimation of the open circuit voltage of the battery. The solubilities of higher than 0.8 mol dm -3 of U(VI) complexes and higher than 0.4 mol dm -3 of a U(IV) complex were obtained in the solvents. The electrode reactions of U(pta) 4 , UO 2 (dpm) 2 , UO 2 (fod) 2 and UO 2 (pta) 2 were first studied and the redox potentials of uranium β-diketonates were thermodynamically discussed. The open circuit voltage is estimated more than 1 V by using Hacac or Hdpm. The larger open circuit voltage is expected when a ligand with the larger basicity is used

Semi-automated potentiometric titration method for uranium characterization

Energy Technology Data Exchange (ETDEWEB)

Cristiano, B.F.G., E-mail: barbara@ird.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Delgado, J.U.; Silva, J.W.S. da; Barros, P.D. de; Araujo, R.M.S. de [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Lopes, R.T. [Programa de Engenharia Nuclear (PEN/COPPE), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, PO Box 68509, Rio de Janeiro, 21945-970 RJ (Brazil)

2012-07-15

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. - Highlights: Black-Right-Pointing-Pointer We developed a semi-automatic version of potentiometric titration method. Black-Right-Pointing-Pointer The method is used for certification and characterization of uranium compounds. Black-Right-Pointing-Pointer The traceability of the method was assured by a K{sub 2}Cr{sub 2}O{sub 7} primary standard. Black-Right-Pointing-Pointer The results of U{sub 3}O{sub 8} reference material analyzed was consistent with certified value. Black-Right-Pointing-Pointer The uncertainty obtained, near 0.01%, is useful for characterization purposes.

Uranium and thorium migration under dislocative metamorphism

International Nuclear Information System (INIS)

Titov, V.K.; Bilibina, T.V.; Dashkova, A.D.; Il'in, V.K.; Makarova, L.I.; Shmuraeva, L.Ya.

1978-01-01

Investigated were peculiarities of uranium and thorium behaviour in the process of dislocation metamorphism on the basis of regional fracture zones of early-proterozoic embedding of Ukrainian, Aldan and Baltic shields. The studied zones correspond to tectonite of green-shale and almandin-amphibolite facies of regional metamorphism according to mineral associations. The most peculiar feature of the tectonites of green-shale facies is uranium presence in migrationally able forms, which can be involved afterwards into the ore process by hydrothermal solutions. Adsorved forms of uranium on the crystal surface or separate grains and in the cracks, as well as microinclusions of uranium minerals, selectively timed to mineral structure defects prevail among easily mobile uranium compounds. Dissolved uranium is present, evidently in gas-liquid inclusions in minerals and pore waters. There forms of uranium presence are peculiar for epidote-chlorite mylonites, as well as cataclasites and diaphthorites related to them by blastomylonites of almandin-amphibolite facies. Wide range of manifestation of this process, caused by multikilometer extension of deep fracture zones permit to consider the formations of green-shale facies of dislocation metamorphism as one of the main uranium sources in deposit formation in different uranium-ore associations different age

Aplicaciones de caucho reciclado: Una revisión de la literatura

Directory of Open Access Journals (Sweden)

Gabriel Jaime Peláez Arroyave

2017-01-01

Full Text Available La generación de residuos de caucho se ha convertido en una preocupación global por su impacto negativo en el medio ambiente y en la salud humana. La legislación ambiental sobre la disposición de este tipo de residuos ha venido aumentando las exigencias a los fabricantes, comercializadores y usuarios, con lo cual se ha acelerado la búsqueda de alternativas para el reaprovechamiento de los residuos de caucho. Este artículo presenta una revisión bibliográfica acerca de las principales tendencias en la utilización del caucho reciclado, incluyendo aplicaciones actualmente comercializadas y otras derivadas tanto de estudios terminados como de líneas de investigación en desarrollo. Las aplicaciones con mayor potencial de volumen consumido son del sector infraestructura y construcciones civiles, especialmente asfaltos, concretos y materiales aislantes para construcción liviana. Algunas aplicaciones con potencial en el futuro cercano son los filtros para la limpieza de aguas contaminadas y como componente en materiales compuestos con matriz termoplástica o en poliuretano. Se evidencia la pertinencia de continuar investigando sobre esta temática, que posee unos retos científicos de alta relevancia, los cuales ameritan la mayor atención por el problema ambiental significativo asociado al manejo de los residuos de caucho.

Uranium. Suppl. Vol. C7

International Nuclear Information System (INIS)

Keim, R.; Keller, C.

1982-01-01

In this supplement volume C7 the nitrogen compounds of uranium-anides, imides, nitrides, nitrites, nitrates are dealt with. Whereas amides, imides and nitrates have only been of scientific interest up to now, uranium nitride and uranylnitrate are of great technological importance. Therefore the description of the chemical and physical characteristics of UN as a potential fuel for future reactors already comprises about 1/4 of this volume. Also the description of uranyl nitrate - as one of the most important commercial forms of uranium and because of its importance in the chemistry of nuclear fuel element reprocessing - comprises many pages. This is supplemented by further uranium nitrides, ternary and polynary nitrides, oxide nitrides, double nitrides of the various valence steps as well as nitrate complexes and ternary and quarternary systems containing uranyl nitrate. The radiation behaviour of UN, and its distribution (liquid/liquid, liquid solid) as well as the complex formation of the uranyl ion with nitrate are described in other volumes of the uranium series. (RB) [de

Scaling properties for the first RE-like mixed valence examples in uranium compounds: U2Ru2Sn and U2RuGa8

International Nuclear Information System (INIS)

Troc, Robert

2006-01-01

The present study was motivated by the scaling characterization of the first example of mixed valence (MV) RE-like behaviour found recently among intermetallic ternary uranium compounds. The χ(T) function for both title compounds has been fitted to the interconfigurational fluctuation (ICF) model of Sales and Wohlleben in order to determine the characteristic fluctuation temperatures T sf and interconfigurational excitation energies E ex . A good scaling, with similar values of T sf like from those derived from the ICF model, has been achieved for both these ternaries by plotting Tχ(T)/C against the reduced T/T sf . Moreover, this scaling follows almost exactly those found earlier in a number of MV- RE compounds

Crystal field effect in the uranium compounds - model calculations for CsUF/sub 6/, Cs/sub 2/UCl/sub 6/ and UCl/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Gajek, Z.; Mulak, J.; Faucher, M.

1987-01-01

A practical crystal field model allowing one to estimate the crystal field parameters from first principles is presented and applied to the actinide compounds. The model results directly from the renormalization (and reduction) procedure of the true Schroedinger equation for an effective Hamiltonian acting on the 5f spin-orbitals only. In practice this approach becomes convergent with the ab initio model of Newman. Three ionic uranium compounds: CsUF/sub 6/, Cs/sub 2/UCl/sub 6/ and UCl/sub 4/ have served as examples of the application. The results obtained, particularly for the first two compounds, are in good agreement with the experimental data. The contributions of different mechanisms responsible for the crystal field effect are discussed.

Evaluación de los Frameworks en el Desarrollo de Aplicaciones Web con Python

Directory of Open Access Journals (Sweden)

Jimmy Rolando Molina Ríos

2016-09-01

Full Text Available Debido a la creciente interacción de los usuarios con sistemas web, surge la necesidad de combinar las funcionalidades de aplicaciones clásicas de escritorio, con la accesibilidad y bajo costo de la publicación de aplicaciones web; dando origen a la elección del mejor marco de trabajo que se adopte a las necesidades de los desarrolladores. Esta investigación presenta un análisis comparativo de los frameworks que trabajan con el lenguaje Python para el desarrollo de aplicaciones web. Para ello el análisis se formuló mediante un modelo de evaluación que se basa en las características de calidad propuestas en la norma ISO/IEC 9126. Estas a su vez permiten establecer sub-características, atributos y métricas para evaluar la calidad de las aplicaciones web. Permitiendo obtener como resultado una matriz para la Evaluación de Frameworks: Django, Pyramid, Turbogear y Web2PY. Los resultados obtenidos mostraron las fortalezas y debilidades de cada framework y fue la base para determinar que Django es el mejor framework para la implementación de desarrollo de sistemas web. Este framework cumplió con todos los indicadores del modelo de evaluación, los resultados redactados al final del documento determinan que tomando en cuenta las métricas de calidad se puede elegir qué marco de trabajo es el que mejor se adapta para el desarrollo de aplicaciones web en la Ciudad de Machala. Antes de realizar una evaluación se considera indispensable conocer y comprender el funcionamiento de los elementos que se vaya a cotejar, para ello es recomendable emplear tablas para la comparación de las características, teniendo como referencia sitios web confiables que aporten documentación sobre los frameworks y el empleo de estándares de calidad para su determinación.

PATRONES DE MULTICULTURALIDAD PARA EL DISEÑO DE APLICACIONES WEB

Directory of Open Access Journals (Sweden)

Víctor Alfonso Zapata

2014-01-01

Full Text Available La diversidad cultural en la Web surge como resultado del crecimiento de internet en los últimos años, logrando que los servicios y aplicaciones Web sean cada vez más utilizados por usuarios de diversas culturas, que en muchos casos terminan siendo diferentes a los usuarios iniciales en los que se basó su diseño y construcción. Este trabajo analiza las diferencias que se presentan en la comunicación multicultural a través de la Web, tomando como punto de partida las dimensiones culturales propuestas por Victor, Hofstede, Trompenaars y Hall. Se identificaron los elementos de diseño Web que están relacionados con las dimensiones culturales y su comportamiento en sitios Web representativos de Argentina, Colombia y España para finalmente construir un conjunto de Patrones de Multiculturalidad para el Diseño de Aplicaciones Web.

Lattice anisotropy in uranium ternary compounds

DEFF Research Database (Denmark)

Maskova, S.; Adamska, A.M.; Havela, L.

2012-01-01

Several U-based intermetallic compounds (UCoGe, UNiGe with the TiNiSi structure type and UNiAl with the ZrNiAl structure type) and their hydrides were studied from the point of view of compressibility and thermal expansion. Confronted with existing data for the compounds with the ZrNiAl structure...

Seguridad y privacidad en aplicaciones Android

OpenAIRE

Piñeiro Ramos, Ismael

2017-01-01

Este trabajo explora las vulnerabilidades existentes en los dispositivos móviles tomando como plataforma el sistema operativo Android. Se pretende estudiar en profundidad las posibilidades de inoculación de código de mal comportamiento y el control del hardware de forma remota. La necesidad de estar permanentemente conectado a través del correo electrónico, las herramientas y aplicaciones para redes sociales, la integración de la grabadora de sonido, vídeo y cámara fotográfica en el propio di...

Lenguaje específico de dominio para aplicaciones de modelación glaciológica

OpenAIRE

Gel, Matías; Urciuolo, Adriana Beatriz; Iturraspe, Rodolfo Javier

2014-01-01

Las aplicaciones de software de modelado de la naturaleza se caracterizan por la complejidad propia de la información y procesos ambientales. Se requiere un nivel de abstracción adecuado y flexibilidad para la modelación de los procesos naturales. Algunas limitaciones del software del dominio provienen del uso de herramientas y lenguajes que carecen de facilidades para representar los conceptos particulares de estas aplicaciones. El Modelado específico del dominio (DSM) propone elevar el nive...

Process for the winning of a concentrate containing uranium and purified phosphoric acid, as well as the concentrate containing uranium and purified phosphoric acid obtained by this process

International Nuclear Information System (INIS)

1980-01-01

The uranium containing concentrate and purified phosphoric acid are obtained by treating wet phosphoric acid with an inorganic fluorine compound (ammonium fluoride) and an aliphatic ketone (acetone) in the presence of a reducing agent (finely divided iron). The ketone is added first and the formed uranium precipitate is separated from the solution. If the fluorine compound is added first, the yield is lowered by a factor of 2. (Th.P.)

Uranium recovery from phosphate fertilizer in the form of a high purity compound

International Nuclear Information System (INIS)

Bunus, F.; Coroianu, T.; Filip, G.; Filip, D.

2001-01-01

Uranium recovery from phosphate fertilizer industry is based on a one cycle extraction-stripping process. The process was experimented on both sulfuric and nitric acid attack of phosphate rock when uranium is dissolved in phosphoric acid (WPA) or phosphonitric (PN) solution respectively. The WPA and PN solution must be clarified. In the first alternative by ageing and settling and in the second by settling in the presence of flocculant. The organic components must be removed on active carbon for WPA only since in the case of nitric attack calcined phosphates are used. In both alternatives uranium is extracted from aqueous acidic solutions in the same time with the rare earths (REE), by di(2-ethylhexyl) phosphate (DEPA) as basic extractants, eventually in the presence of octylphosphine oxide (TOPO) as synergic agent. The stripping process is carried out in two stages: in the first stage REE are stripped and precipitated by HF or NH 4 F + H 2 S0 4 and in the second stage uranium as U(VI) is stripped by the same reagents but in the presence of Fe(II) as reductant for U(VI) to U(IV) inextractible species. Tetravalent uranium is also precipitated as green cake either UF 4 xH 2 0 or (NH 4 ) 7 U 6 F 31 as dependent on reagents HF or NH 4 F + H 2 S0 4 . Uranium stripping is possible for PN solution only if HNO 3 partially extracted is previously washed out by a urea solution. The green cake washed and filtered is dissolved in nitric acid in presence of Al(OH)3 as complexant for F. The filtered nitric solution is adjusted to 3-5 mol/L HNO 3 and extracted by 20% TBP when uranium is transferred to the organic phase which after scrubbing is stripped in the classic way with acidulated (HN0 3 ) demineralized water. Uranium is precipitated as diuranate of high purity. Rare earths left in the aqueous raffinate are extracted by pure TBP from 8-10 mol/L HNO 3 medium. The stripping process takes place with acidulated water. Rare earths are precipitated as hydroxides. (author)

Uranium nucleophilic carbene complexes

International Nuclear Information System (INIS)

Tourneux, Jean-Christophe

2012-01-01

The only stable f-metal carbene complexes (excluding NHC) metals f present R 2 C 2- groups having one or two phosphorus atoms in the central carbon in alpha position. The objective of this work was to develop the chemistry of carbenes for uranium (metal 5f) with the di-anion C{Ph 2 P(=S)} 2 2- (SCS 2- ) to extend the organometallic chemistry of this element in its various oxidation states (+3-+6), and to reveal the influence of the 5f orbitals on the nature and reactivity of the double bond C=U. We first isolated the reactants M(SCHS) (M = Li and K) and demonstrated the role of the cation M + on the evolution of the di-anion M 2 SCS (M = Li, K, Tl) which is transformed into LiSCHS in THF or into product of intramolecular cyclization K 2 [C(PhPS) 2 (C 6 H 4 )]. We have developed the necessary conditions mono-, bis- and tris-carbene directly from the di-anion SCS 2- and UCl 4 , as the precursor used in uranium chemistry. The protonolysis reactions of amides compounds (U-NEt 2 ) by the neutral ligand SCH 2 S were also studied. The compounds [Li(THF)] 2 [U(SCS)Cl 3 ] and [U(SCS)Cl 2 (THF) 2 ] were then used to prepare a variety of cyclopentadienyl and mono-cyclo-octa-tetra-enyliques uranium(IV) carbene compounds of the DFT analysis of compounds [M(SCS)Cl 2 (py) 2 ] and [M(Cp) 2 (SCS)] (M = U, Zr) reveals the strong polarization of the M=C double bond, provides information on the nature of the σ and π interactions in this binding, and shows the important role of f orbitals. The influence of ancillary ligands on the M=C bond is revealed by examining the effects of replacing Cl - ligands and pyridine by C 5 H 5 - groups. Mulliken and NBO analyzes show that U=C bond, unlike the Zr=C bond, is not affected by the change in environment of the metal center. While the oxidation tests of carbene complexes of U(IV) were disappointing, the first carbene complex of uranium (VI), [UO 2 (SCS)(THF) 2 ], was isolated with the uranyl ion UO 2 2+ . The reactions of compounds UO 2 X 2

Investigación en Progreso: Ingeniería de Software en el Desarrollo de Aplicaciones Sensibles al Contexto

Directory of Open Access Journals (Sweden)

Marisa D. Panizzi

2015-10-01

Full Text Available Las aplicaciones han ido evolucionando independientemente de cuál sea su dominio de aplicación, actualmente nos encontramos con aplicaciones que pueden brindar servicios de acuerdo a la ubicación, tiempo y perfil del usuario. Este tipo de aplicaciones que brindan estos servicios se las conoce como Aplicaciones Sensibles al Contexto (CA – Context Aware, en este tipo de aplicaciones predominan los dispositivos móviles y el perfil del usuario. La evolución varía en función de la forma de uso de la computadora, es decir que se brinden servicios a pedido del usuario o que se brinden servicios de manera automática. Para acompañar la evolución de este tipo de aplicaciones, la Ingeniería de Software ha focalizado sus esfuerzos en aspectos relacionados a separar la aplicación de todo lo concerniente a la captación, interpretación, control y supervisión de la información contextual. Es decir que desde el punto de vista del diseño, se separe la conducta sensible al contexto de la conducta propia de la aplicación con el propósito de que ambos tipos de aplicaciones pueden evolucionar en forma independiente además de reducir el tiempo de desarrollo en este tipo de sistemas. Este proyecto presenta una sub línea, la cual orientará sus aportes, en la consolidación de un framework de gestión contextual de dos o tres variables de contexto como por ejemplo: la ubicación, considerando la construcción de la documentación relevante que lo respalde como así también su fase de experimentación con una aplicación que permitirá a los usuarios de la comunidad universitaria UM hacer uso de los servicios ofrecidos por la misma. La segunda sub línea, se vincula al Área de la Ingeniería de Requisitos, pretendiendo obtener un modelo para la especificación de requisitos de software para sistemas sensibles al contexto.

Improvements in or relating to calcining reducible compounds

International Nuclear Information System (INIS)

Cole, E.A.; Peterson, R.S.

1974-01-01

Apparatus is described for calcining compounds of uranium compounds to temperatures of up to about 1000 0 C to produce UO 2 powders of uniform quality and having an oxygen content of less than 2.2 atoms of oxygen per atom of uranium. The apparatus comprises discharge and cooling means having an inlet end operatively joined with an air tight seal to a rotating Kiln to receive hot UO 2 powder therefrom without contact with air. (author)

Semi-automated potentiometric titration method for uranium characterization.

Science.gov (United States)

Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

2012-07-01

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. Copyright © 2011 Elsevier Ltd. All rights reserved.

Use of electrothermal atomization for determining metallic impurities in nuclearly pure uranium compounds

International Nuclear Information System (INIS)

Franco, M.B.

1986-01-01

Atomic absorption spectrometry with electrothermal atomization was used for the determination of Al, Cd, Cr, Fe, Mn, Mo and Ni as impurities in uranium oxide samples. The determinations were performed in solubilized samples both with and without uranium separation as well as in solid samples. (Author) [pt

Use of electrothermal atomization for determining metallic impurities in nuclearly pure uranium compounds

International Nuclear Information System (INIS)

Franco, M.B.

1985-01-01

Atomic absorption spectrometry with electrothermal atomization was used for the determination of Al, Cd, Cr, Fe, Mn, Mo and Ni as impurities in uranium oxide samples. The determinations were performed in solubilized samples both with and without uranium separation as well as in solid samples. (Author) [pt

Uranium decontamination of common metals by smelting, a review (handbook)

International Nuclear Information System (INIS)

Mautz, E.W.; Briggs, G.G.; Shaw, W.E.; Cavendish, J.H.

1975-01-01

The published and unpublished literature relating to the smelting of common metals scrap contaminated with uranium-bearing compounds has been searched and reviewed. In general, standard smelting practice produces ingots having a low uranium content, particularly for ferrous, nickel, and copper metals or alloys. Aluminum recovered from uranium contaminated scrap shows some decontamination by smelting but the uranium content is not as low as for other metals. Due to the heterogeneous nature and origin of scrap metals contaminated with uranium, information is frequently missing as to the extent of the initial contamination and the degree of decontamination obtained. The uranium content of the final cast ingots is generally all that is available. Results are summarized below by the primary composition of the uranium contaminated scrap metal. (U.S.)

Application of frequency converters in industry; Aplicacion de convertidores de frecuencia en la industria

Energy Technology Data Exchange (ETDEWEB)

Adame Gonzalez, A.; Aguilar Galvan, A. [Ingenieria Energetica Integral, S.A. de C.V. (Mexico)

1997-12-31

Some of the applications of the frequency converters will be analyzed, as well as the parameters to be considered for the feasibility of its application evaluation. It is also described how an energy evaluation is accomplished and finally a series of actions are enlisted conducting to the energy savings. [Espanol] Se presentaran algunas de las aplicaciones de los convertidores de frecuencia. Ademas se indicaran los parametros a registrar para evaluar la factibilidad de aplicacion de los mismos, se describe como ejecutar la evaluacion energetica y finalmente se listan una serie de acciones que conducen a lograr ahorros de energia.

Application of frequency converters in industry; Aplicacion de convertidores de frecuencia en la industria

Energy Technology Data Exchange (ETDEWEB)

Adame Gonzalez, A; Aguilar Galvan, A [Ingenieria Energetica Integral, S.A. de C.V. (Mexico)

1998-12-31

Some of the applications of the frequency converters will be analyzed, as well as the parameters to be considered for the feasibility of its application evaluation. It is also described how an energy evaluation is accomplished and finally a series of actions are enlisted conducting to the energy savings. [Espanol] Se presentaran algunas de las aplicaciones de los convertidores de frecuencia. Ademas se indicaran los parametros a registrar para evaluar la factibilidad de aplicacion de los mismos, se describe como ejecutar la evaluacion energetica y finalmente se listan una serie de acciones que conducen a lograr ahorros de energia.

Análisis del comportamiento contextual del usuario y su relación con el consumo de aplicaciones móviles

OpenAIRE

Luis Antonio Rojas-Potosí; Leandro Krug Wives; Alejandro Fernández; Juan Carlos Corrales

2014-01-01

El mercado de aplicaciones móviles crece aceleradamente, captando la atención sobre el análisis del consumo de las mismas para mejorar su recomendación y la satisfacción del usuario, soportado en la búsqueda de información que permita explicar la ocurrencia de eventos del ciclo de vida de las aplicaciones. En este sentido algunos estudios muestran una fuerte relación entre dichos eventos e información sobre la situación contextual actual del usuario y su registro de consumo de aplicaciones. S...

Analysis of prospecting effect of polonium survey and geoelectric survey extracted uranium and molybdenum in the south of Shengyuan volcanic basin

International Nuclear Information System (INIS)

Jin Hehai

2007-01-01

Polonium survey and geoelectric survey extracted uranium and molybdenum show that compound anomaly with sharp anomaly peak of the curve of polonium-210, uranium, molybdenum appears along many survey lines in Bakou area, Shengyuan volcanic basin, which may reflect the enrichment of uranium and molybdenum in rock formation and soil layer. By contrasting the anomaly curve to that above the buried uranium deposit, it is recognized that compound anomaly is closely related to the uranium mineralization condition in the area and some favourable sites for uranium metallogeny have been predicated. (authors)

Study of uranium(4) phosphites

International Nuclear Information System (INIS)

Avduevskaya, K.A.; Rozanov, I.A.; Mironova, V.S.

1977-01-01

Neutral and monosubstituted uranium phosphites U(HPO 3 ) 2 x2H 2 O and U(H 2 PO 3 ) 4 x2H 2 O and pyrophosphite U(H 2 P 2 O 5 ) 2 have been separated and identified. Thermal stability of the sepaated compounds have been studied. Upon heating U(HPO 3 )x2H 2 O up to 120-190 deg C, hydrate water is removed. The final product obtained on heating up to 900 deg C is identified as UP 2 O 7 . In the case of U(H 2 PO 3 ) 4 x2H 2 O, crystallization water is removed stepwise within the ranges of 60-140 deg C and 160-270 deg C. Complete removal of water yields a compound of U(H 2 P 2 O 5 ). It has been established that uranium phosphites are isomorphous to the corresponding thorium phosphites

Modern x-ray spectral methods in the study of the electronic structure of actinide compounds: Uranium oxide UO2 as an example

Directory of Open Access Journals (Sweden)

Teterin Yury A.

2004-01-01

Full Text Available Fine X-ray photo electron spectral (XPS structure of uranium dioxide UO2 in the binding energy (BE range 0-~č40 eV was associated mostly with the electrons of the outer (OVMO (0-15 eV BE and inner (IVMO (15-40 eV BE valence molecular orbitals formed from the incompletely U5f,6d,7s and O2p and completely filled U6p and O2s shells of neighboring uranium and oxygen ions. It agrees with the relativistic calculation results of the electronic structure for the UO812–(Oh cluster reflecting uranium close environment in UO2, and was confirmed by the X-ray (conversion electron, non-resonance and resonance O4,5(U emission, near O4,5(U edge absorption, resonance photoelectron, Auger spectroscopy data. The fine OVMO and IVMO related XPS structure was established to yield conclusions on the degree of participation of the U6p,5f electrons in the chemical bond, uranium close environment structure and interatomic distances in oxides. Total contribution of the IVMO electrons to the covalent part of the chemical bond can be comparable with that of the OVMO electrons. It has to be noted that the IVMO formation can take place in compounds of any elements from the periodic table. It is a novel scientific fact in solid-state chemistry and physics.

Autoría de aplicaciones móviles para el análisis de datos

OpenAIRE

Person Montero, Tatiana

2018-01-01

La incorporación de aplicaciones móviles en diversos entornos genera una gran cantidad de información resultante de la interacción de los usuarios con estas aplicaciones. El análisis de esta información puede ser de gran utilidad para el profesional, ya que le puede facilitar la toma de decisiones o la valoración del proceso que esté aplicando, permitiendo mejorar los resultados o detectar determinados patrones. La información recogida se puede definir siguiendo una serie de características: ...

Thermodynamic properties of uranium in gallium–aluminium based alloys

International Nuclear Information System (INIS)

Volkovich, V.A.; Maltsev, D.S.; Yamshchikov, L.F.; Chukin, A.V.; Smolenski, V.V.; Novoselova, A.V.; Osipenko, A.G.

2015-01-01

Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga–Al alloys containing 0.014–20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated. - Highlights: • Thermodynamics of uranium is determined in Ga–Al alloys of various compositions. • Uranium in the mixed alloys interacts with both components, Ga and Al. • Interaction of U with Al increases with decreasing temperature. • Activity and solubility of uranium depend on Al content in Ga–Al alloys.

Thermodynamic properties of uranium in gallium–aluminium based alloys

Energy Technology Data Exchange (ETDEWEB)

Volkovich, V.A., E-mail: v.a.volkovich@urfu.ru [Department of Rare Metals and Nanomaterials, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Maltsev, D.S.; Yamshchikov, L.F. [Department of Rare Metals and Nanomaterials, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Chukin, A.V. [Department of Theoretical Physics and Applied Mathematics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Smolenski, V.V.; Novoselova, A.V. [Institute of High-Temperature Electrochemistry UD RAS, Ekaterinburg, 620137 (Russian Federation); Osipenko, A.G. [JSC “State Scientific Centre - Research Institute of Atomic Reactors”, Dimitrovgrad, 433510 (Russian Federation)

2015-10-15

Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga–Al alloys containing 0.014–20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated. - Highlights: • Thermodynamics of uranium is determined in Ga–Al alloys of various compositions. • Uranium in the mixed alloys interacts with both components, Ga and Al. • Interaction of U with Al increases with decreasing temperature. • Activity and solubility of uranium depend on Al content in Ga–Al alloys.

Alloys of uranium and aluminium with low aluminium content; Alliages uranium-aluminium a faible teneur en aluminium

Energy Technology Data Exchange (ETDEWEB)

Cabane, G; Englander, M; Lehmann, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

Uranium, as obtained after spinning in phase {gamma}, presents an heterogeneous structure with large size grains. The anisotropic structure of the metal leads to an important buckling and surface distortion of the fuel slug which is incompatible with its tubular cladding for nuclear fuel uses. Different treatments have been made to obtain an isotropic structure presenting high thermal stability (laminating, hammering and spinning in phase {alpha}) without success. Alloys of uranium and aluminium with low aluminium content present important advantage in respect of non allied uranium. The introduction of aluminium in the form of intermetallic compound (UAl{sub 2}) gives a better resistance to thermal fatigue. Alloys obtained from raw casting present an improved buckling and surface distortion in respect of pure uranium. This improvement is obtained with uranium containing between 0,15 and 0,5 % of aluminium. An even more improvement in thermal stability is obtained by thermal treatments of these alloys. These new characteristics are explained by the fine dispersion of the UAl{sub 2} particles in uranium. The results after treatments obtained from an alloy slug containing 0,4 % of aluminium show no buckling or surface distortion and no elongation. (M.P.)

Analysis of uranium and of some of its compounds and alloys. Copper spectrophotometric determination

International Nuclear Information System (INIS)

Copper determination in uranium, uranium oxides (UO 2 , UO 3 , U 3 O 8 ), ammonium diuranate, U-Al-Fe alloy (700 ppm Al and 300 ppm Fe) and U-Mo alloy (1.1 percent Mo) by acid dissolution reduction of copper by hydroxylamine hydrochloride and formation of a complex with diquinolyle-2,2' amyl alcohol (pH value 6 to 7) and spectrophotometry at 550 nm. The method is applicable for copper content between 5 to 40 ppm in respect of uranium contained in the material [fr

Low-resolution gamma-ray measurements of uranium enrichment

International Nuclear Information System (INIS)

Sprinkle, J.K. Jr.; Christiansen, A.; Cole, R.; Collins, M.L.

1996-01-01

Facilities that process special nuclear material perform periodic inventories. In bulk facilities that process low-enriched uranium, these inventories and their audits are based primarily on weight and enrichment measurements. Enrichment measurements determine the 211 U weight fraction of the uranium compound from the passive gamma-ray emissions of the sample. Both international inspectors and facility operators rely on the capability to make in-field gamma-ray measurements of uranium enrichment. These users require rapid, portable measurement capability. Some in-field measurements have been biased, forcing the inspectors to resort to high-resolution measurements or mass spectrometry to accomplish their goals

Analysis of a Uranium Oxide Sample Interdicted in Slovakia (FSC 12-3-1)

Energy Technology Data Exchange (ETDEWEB)

Borg, Lars E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dai, Zurong [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Eppich, Gary R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gaffney, Amy M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Genetti, Victoria G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Grant, Patrick M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gray, Leonard W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Holiday, Kiel S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hutcheon, Ian D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kayzar, Theresa M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Klunder, Gregory L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Knight, Kimberly B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kristo, Michael J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lindvall, Rachel E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Marks, Naomi E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ramon, Christina E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ramon, Erick C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Robel, Martin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Roberts, Sarah K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schorzman, Kerri C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sharp, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Singleton, Michael J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Williams, Ross W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-01-17

We provide a concise summary of analyses of a natural uranium sample seized in Slovakia in November 2007. Results are presented for compound identification, water content, U assay, trace element abundances, trace organic compounds, isotope compositions for U, Pb, Sr and O, and age determination using the ²³⁴U – ²³⁰Th and ²³⁵U – ²³¹Pa chronometers. The sample is a mixture of two common uranium compounds - schoepite and uraninite. The uranium isotope composition is indistinguishable from natural; ²³⁶U was not detected. The O, Sr and Pb isotope compositions and trace element abundances are unremarkable. The ²³⁴U – ²³⁰Th chronometer gives an age of 15.5 years relative to the date of analysis, indicating the sample was produced in January 1997. A comparison of the data for this sample with data in the Uranium Sourcing database failed to find a match, indicating the sample was not produced at a facility represented in the database.

Feasibility studies on electrochemical recovery of uranium from solid wastes contaminated with uranium using 1-butyl-3-methylimidazorium chloride as an electrolyte

Energy Technology Data Exchange (ETDEWEB)

Ohashi, Yusuke, E-mail: ohhashi.yusuke@jaea.go.jp [Ningyo-toge Environmental Engineering center, Japan Atomic Energy Agency, 1550 Kamisaibara, Kagamino-cho, Tomata-gun, Okayama 708-0698 (Japan); Harada, Masayuki [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-34 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Asanuma, Noriko [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Ikeda, Yasuhisa [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-34 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

2015-09-15

Highlights: • The uranium component of steel wastes and spent NaF adsorbent are easily dissolved into BMICl. • The uranyl(VI) species in BMICl are reduced to U(V) irreversibly around −0.8 to −1.3 V. • The dissolved uranium species in BMICl are recovered as black deposits electrolytically. • The deposit is the mixtures of U(IV) and U(VI) compounds containing O, F, Cl, and N elements. - Abstract: In order to examine feasibility of the electrochemical deposition method for recovering uranium from the solid wastes contaminated with uranium using ionic liquid as electrolyte, we have studied the electrochemical behavior of each solution prepared by soaking the spent NaF adsorbents and the steel waste contaminated with uranium in BMICl (1-butyl-3-methyl- imidazolium chloride). The uranyl(VI) species in BMICl solutions were found to be reduced to U(V) irreversibly around −0.8 to −1.3 V vs. Ag/AgCl. The resulting U(V) species is followed by disproportionation to U(VI) and U(IV). Based on the electrochemical data, we have performed potential controlled electrolysis of each solution prepared by soaking the spent NaF adsorbents and steel wastes in BMICl at −1.5 V vs. Ag/AgCl. Black deposit was obtained, and their composition analyses suggest that the deposit is the mixtures of U(IV) and U(VI) compounds containing O, F, Cl, and N elements. From the present study, it is expected that the solid wastes contaminated with uranium can be decontaminated by treating them in BMICl and the dissolved uranium species are recovered electrolytically.

Uranium dioxide calcining apparatus

International Nuclear Information System (INIS)

Cole, E.A.; Peterson, R.S.

1978-01-01

This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO 2 ) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO 2 , means for cooling the UO 2 to a temperature of below 100 deg C and conveying the cooled UO 2 to storage or to subsequent UO 2 processing apparatus where it finally comes into contact with air, the means for receiving cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO 2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO 2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means. (author)

The discovery of uranium - on the history of pitchblende

International Nuclear Information System (INIS)

Stoll, W.

1989-01-01

Two hundred years ago, uranium was discovered by the pharmacist and chemist Martin Heinrich Klaproth in Berlin as the 18th metal. In a changing world he studied the emerging new chemical theories and pleaded unwaveringly in favor of abandoning outmoded concepts. Klaproth was the first scientific author who published not only his personal idea of the composition of a new compound, but also gave all details of his investigation. In this way, he recognized new elements first in a speculative process and then on the basis of factual confirmation. Klaproth collected his works in six volumes, among other publications, and was one of the main contributors to an encyclopaedic chemical dictionary. He was the first full professor of chemistry at the new university of Berlin. For a long time, uranium compounds were used to stain glass and porcelain as well as in painting and in the graphic arts. Without realizing it, Henri Becquerel in 1896 first recognized the radioactive properties of the uranium compounds, which were confirmed by the Curies and by G. Bemont in the discovery of radium in residues from Joachimsthal pitchblende. (orig.) [de

Potential synergy between two renal toxicants: DTPA and uranium

International Nuclear Information System (INIS)

Muller, D.; Houpert, P.; Henge Napoli, M.H.; Paquet, F.; Muller, D.; Henge Napoli, M.H.; Metivier, H.

2006-01-01

At present, the most appropriate therapeutic approach to treat an accidental contamination with plutonium and uranium oxide mixture (MOX) is administration of diethylene-triamine-penta-acetate acid (DTPA) in order to accelerate plutonium excretion. As uranium and DTPA are both nephro-toxic compounds, the administration of DTPA after a contamination containing uranium could enhance the nephro-toxic effects of uranium. The aim of the present work was to study in vitro on a kidney proximal tubule cell line (LLC-PK 1 ) the cytotoxicity induced by increasing concentrations of uranium in presence of 3 different chemical forms of DTPA. The results showed that the DTPA used alone induced no cytotoxicity at the concentration used here (420 μM). However, this concentration of DTPA increased the cytotoxicity induced by uranium. This increase was maximal for uranium concentrations close to the lethal concentration for 50% of the cells and reached 37, 31 and 28% for anhydrous DTPA, Na 3 CaDTPA and Na 3 ZnDTPA, respectively. These results suggest that administration of DTPA could enhance the nephrotoxicity induced by uranium. (authors)

High temperature behavior of metallic inclusions in uranium dioxide

International Nuclear Information System (INIS)

Yang, R.L.

1980-08-01

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

Reactivity of uranium(IV) bridged chalcogenido complexes UIV–E–UIV (E = S, Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

OpenAIRE

Franke, Sebastian M.; Heinemann, Frank W.; Meyer, Karsten

2014-01-01

We report the syntheses, electronic properties, and molecular structures of a series of polychalcogenido-bridged dinuclear uranium species. These complexes are supported by the sterically encumbering but highly flexible, single N-anchored tris(aryloxide) chelator (AdArO)3N3−. Reaction of an appropriate uranium precursor, either the U(III) starting material, [((AdArO)3N)U(DME)], or the dinuclear mono-chalcogenido-bridged uranium(IV/IV) compounds [{((AdArO)3N)U(DME)}2(μ-E)] (E = S, Se), with el...

US uranium reserves

International Nuclear Information System (INIS)

Hansen, M.V.

1981-01-01

The current low level of demand, compounded by rapidly rising costs and low prices, has caused a significant reduction in drilling for uranium in the United States, and the trend is likely to continue for a few more years. The effect on uranium reserves will be fewer additions to reserves because less exploration is being done. Further reductions will occur, especially in low-cost reserves, because of increasing costs, continuing depletion through production, and erosion through the high grading of deposits to fulfill previous contractual commitments. During the past several years, it has been necessary to increase the upper reserve cost level twice to compensate for rising costs. Rising costs are reducing the $15 reserves, the cost category corresponding most closely to the present market price, to an insignificant level. An encouraging factor related to US uranium reserves is that the US position internationally, as far as quantity is concerned, is not bad for the longer term. Also, there is a general opinion that US consumers would rather contract for domestic uranium than for foreign because of greater assurance of supply. Still another factor, nearly impossible to assess, is what effect rising costs in other countries will have on their uranium reserves. The annual conferences between the Grand Junction Area Office staff and major uranium companies provide a broad overview of the industry's perception of the future. It is not optimistic for the short term. Many companies are reducing their exploration and mining programs; some are switching to other more marketable mineral commodities, and a few are investing more heavily in foreign ventures. However, there is general optimism for the long term, and many predict a growth in demand in the mid-1980s. If the industry can survive the few lean years ahead, rising prices may restore its viability to former levels

The solubility of uranium trioxide simulated lung fluid

International Nuclear Information System (INIS)

Kravchiks, T.; Kol, R.; Prager, A.; German, U.; Oved, S.; Laichter, Y.

1997-01-01

Uranium trioxide is an important intermediate compound in the uranium production process. Inhalation of UO 3 aerosols can occur during this process. To assess the radiation dose from the intake of this compound it is necessary to know its transportability class, based on its dissolution rate in lung fluid. The International Commission on Radiological Protection (ICRP) has assigned UO 3 to Inhalation Class W (lung retention half-time of 10 to 100 days). A solubility study of UO 3 in a simulated lung fluid has been carried out using a batch/filter replacement method. Two tests were conducted over a 100-days period, during which 17 samples were collected and analyzed for their dissolved uranium content. The results show that about 40% of the total uranium was dissolved during the first days and nearly all was dissolved during 100 days. Expressed as the fraction of the total uranium remaining undissolved as a function of time, using a non-linear least squares regression fit, it was found that the solubility of UO 3 in simulated lung fluid could be expressed as a combination of two Inactions: about 25% of the UO 3 could be classified as type D (with lung retention half-time of several hours) and about 75% as type W (with half-time of 10-20 days). This classification is in agreement with recent investigations and indicates that UO 3 is more soluble than considered by ICRP. (authors)

Sistema de realidad aumentada para aplicaciones Android

OpenAIRE

Fernández Sánchez, Natalia Mercedes

2012-01-01

El objetivo principal de este proyecto es la creación de un sistema de realidad aumentada para el sistema operativo Android con idea de que sea utilizado para la creación de un videojuego, pero que a su vez sea lo suficientemente versátil como para poder utilizarse en otro tipo de aplicaciones. De este objetivo principal podemos obtener los objetivos secundarios: - Conocer las características que ofrecen los teléfonos móviles y como éstas pueden ser aprovechadas para la crea...

La evaluación de las aplicaciones de lectura web: un paso más en el proceso de editorialización de la web

Directory of Open Access Journals (Sweden)

Noelia Patón Rodríguez

2016-11-01

Full Text Available En el desarrollo de la lectura digital confluyen una serie de factores que pasan entre otras cuestiones por la evolución tecnológica de los dispositivos y el desarrollo de numerosas aplicaciones que facilitan la lectura al tiempo que está provocando cambios en los hábitos de lectura tal y como lo demuestran los diferentes informes. Uno de los desarrollos tecnológicos está relacionado con el diseño de aplicaciones específicas para la lectura en la pantalla del ordenador, son las llamadas aplicaciones de lectura web. En este artículo, tras definir qué son las aplicaciones de lectura web se explican los objetivos y el proceso seguido para la selección, definición y sistematización de los parámetros que servirán para la evaluación de las aplicaciones de lectura web.

Analyses of uranium series nuclides by alpha spectrometer on the uranium deposit

International Nuclear Information System (INIS)

Wismawati, T.

2000-01-01

The research is one of the program which was planned by PNC (Power Reactor and Nuclear Fuel Development Corporation). In this research the analyses of the uranium series nuclide of rock samples from uranium Tono deposit, Japan have been carried out. The 17 samples were collected from Tsukiyoshi Fault, at Gallery X on Shaft 2 consist of granite, sedimentary rocks and fault area. The aim of the research is to determine the area of U accumulation, equilibrium and leaching. The samples were treated by chemical reagent, separated by ion exchange resin and extracted by organic compounds. The uranium and thorium were deposited on the stainless steel plate surface by the electrolysis process. The activity of uranium and thorium was determined by alpha spectrometer. From the analyses data have been obtained that shows that the maximum activity of 238 U is 3.6798±0.1873 Bq/g, activity 234 U is 3.5450±0.1805 Bq/g and activity 230 Th is 3.6720±0.1868 Bq/g. The ratio figure 234 U/ 238 U versus 2 34 U / 2 30 T h has been drawn. As the conclusion, 6 samples point (No.3, 5, 8, 11, 13 and 16) lied in or on the boundary of the uranium accumulation area, 7 samples (No. 4, 6, 9, 10, 12, 15 and 17) are very close to the equilibrium position, 4 points (No. 1, 2, 7, and 14) in the leaching process. (author)

Properties of tritium and its compounds

International Nuclear Information System (INIS)

Belovodskij, L.F.; Gaevoj, V.K.; Grishmanovskij, V.I.

1985-01-01

Ways of tritium preparation and different aspects of its application are considered. Physicochemical properties of this isotope and some compounds of it - tritium oxides, lithium, titanium, zirconium, uranium tritides, tritium organic compounds - are discussed. In particular, diffusion of tritium and its oxide through different materials, tritium oxidation processes, decomposition of tritium-containing compounds under the action of self-radiation are considered. Main radiobiological tritium properties are described

Method of semi-automatic high precision potentiometric titration for characterization of uranium compounds; Metodo de titulacao potenciometrica de alta precisao semi-automatizado para a caracterizacao de compostos de uranio

Energy Technology Data Exchange (ETDEWEB)

Cristiano, Barbara Fernandes G.; Dias, Fabio C.; Barros, Pedro D. de; Araujo, Radier Mario S. de; Delgado, Jose Ubiratan; Silva, Jose Wanderley S. da, E-mail: barbara@ird.gov.b, E-mail: fabio@ird.gov.b, E-mail: pedrodio@ird.gov.b, E-mail: radier@ird.gov.b, E-mail: delgado@ird.gov.b, E-mail: wanderley@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Lopes, Ricardo T., E-mail: ricardo@lin.ufrj.b [Universidade Federal do Rio de Janeiro (LIN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Lab. de Instrumentacao Nuclear

2011-10-26

The method of high precision potentiometric titration is widely used in the certification and characterization of uranium compounds. In order to reduce the analysis and diminish the influence if the annalist, a semi-automatic version of the method was developed at the safeguards laboratory of the CNEN-RJ, Brazil. The method was applied with traceability guaranteed by use of primary standard of potassium dichromate. The standard uncertainty combined in the determination of concentration of total uranium was of the order of 0.01%, which is better related to traditionally methods used by the nuclear installations which is of the order of 0.1%

Receptor GNSS multiantena para aplicaciones aeroespaciales

OpenAIRE

Cogo, Jorge; López La Valle, Ramón G.; Puga, Gerardo L.; Smidt, Javier A.; Díaz, Juan G.; García, Javier Gonzalo; Roncagliolo, Pedro Agustín; Muravchik, Carlos Horacio

2013-01-01

La determinación de la posición y velocidad del vehículo es una de las tareas críticas en las aplicaciones aeroespaciales como es el caso de aviones, satélites o cohetes. En los últimos años esta tarea se ha visto favorecida por el despliegue de los Sistemas de Navegación Global por Satélite (GNSS). Estos sistemas, utilizando como base una constelación de satélites que envían señales a la superficie terrestre, permiten que un usuario que cuente con un receptor adecuado pueda obtener esta info...

Desarrollo de aplicaciones móviles bajo la plataforma de Iphone

Directory of Open Access Journals (Sweden)

Jaime Esteban Roa Castañeda

2011-07-01

Full Text Available El iPhone es un dispositivo móvil que lleva cerca de cinco años en el mercado de celulares, y sus funciones van más allá del uso como tal de un teléfono celular, gracias al App Store, que ofrece miles de aplicaciones creadas por desarrolladores alrededor del mundo. La arquitectura y el sistema operativo del iPhone permiten que las aplicaciones creadas por desarrolladores usen tecnologías especializadas para diferentes tipos de usuarios, permitiendo incluir características como gráficos de alta definición o usar accesorios de hardware, haciendo uso de los frameworks soportados por la arquitectura del dispositivo; todo esto es posible crearlo gracias a las herramientas de desarrollo provistas por Apple. El almacenamiento y la persistencia de datos se ven plasmados en el desarrollo de una aplicación caso de estudio que hace uso de Core Data para el manejo de la información.

Uranium accumulation in CTF and ETF-II rotors

International Nuclear Information System (INIS)

1987-06-01

In the expanding technology of uranium enrichment by gas centrifuge, efforts are being made to become more and more familar with the reactions taking place inside the rotor tube while the machine is operational. Inspection of the rotor after shutdown shows where uranium containing compounds are deposited. A study of these deposits from several ETF, CTF and CPL rotors has provided insight as to accumulation amounts, its composition and deposition parameters involved

Anticorrosion protection of uranium

Energy Technology Data Exchange (ETDEWEB)

Goncharov, Ivan D.; Kazakovskaya, Tatiana; Tukmakov, Victor; Shapovalov, Vyacheslav [Russian Federal Nuclear Center-VNIIEF, 37, Mira Ave., RU-607190 Sarov (Nizhnii Gorod), 010450 (Russian Federation)

2004-07-01

Uranium in atmospheric conditions is non-stable. Sloughing products are being generated on its surface during storage or use. These corrosion products make many difficulties because of necessity to provide personnel safety. Besides, uranium corrosion may cause damage in parts. The first works devoted to uranium corrosion were performed in the framework of the USA Manhattan Project in the early forties of last century. Various methods of uranium protection were investigated, among them the galvanic one was the most studied. Later on the galvanic technology was patented. The works on this problem remains urgent up to the present time. In Russia, many methods of uranium corrosion protection, mainly against atmospheric corrosion, were tried on. In particular, such methods as diffusion zinc and paint coating were investigated. In the first case, a complex intermetallic U-Zn compound was formed but its protection was not reliable enough, this protection system was inconvenient and uncertain and that is why an additional paint coating was necessary. In the case of paint coatings another problem appeared. It was necessary to find such a coating where gas-permeability would prevail over water-permeability. Otherwise significant uranium corrosion occurs. This circumstance together with low mechanical resistance of paint coatings does not allow to use paint coating for long-term protection of uranium. Currently, there are following methods of uranium protection: ion-plasma, galvanic and thermo-vacuum annealing. These are described in this paper. In the end the issue of corrosion protection in reactor core zones is addressed. Here the greatest difficulties are caused when enriched uranium heated up to 500 deg. C needs anticorrosion protection. In this case various metal coatings are not reliable because of brittle inter-metallide formation. The reliable protection may be provided only up to the temperature plus 400 - 500 deg. C with the help of galvanic copper coating since

Anticorrosion protection of uranium

International Nuclear Information System (INIS)

Goncharov, Ivan D.; Kazakovskaya, Tatiana; Tukmakov, Victor; Shapovalov, Vyacheslav

2004-01-01

Uranium in atmospheric conditions is non-stable. Sloughing products are being generated on its surface during storage or use. These corrosion products make many difficulties because of necessity to provide personnel safety. Besides, uranium corrosion may cause damage in parts. The first works devoted to uranium corrosion were performed in the framework of the USA Manhattan Project in the early forties of last century. Various methods of uranium protection were investigated, among them the galvanic one was the most studied. Later on the galvanic technology was patented. The works on this problem remains urgent up to the present time. In Russia, many methods of uranium corrosion protection, mainly against atmospheric corrosion, were tried on. In particular, such methods as diffusion zinc and paint coating were investigated. In the first case, a complex intermetallic U-Zn compound was formed but its protection was not reliable enough, this protection system was inconvenient and uncertain and that is why an additional paint coating was necessary. In the case of paint coatings another problem appeared. It was necessary to find such a coating where gas-permeability would prevail over water-permeability. Otherwise significant uranium corrosion occurs. This circumstance together with low mechanical resistance of paint coatings does not allow to use paint coating for long-term protection of uranium. Currently, there are following methods of uranium protection: ion-plasma, galvanic and thermo-vacuum annealing. These are described in this paper. In the end the issue of corrosion protection in reactor core zones is addressed. Here the greatest difficulties are caused when enriched uranium heated up to 500 deg. C needs anticorrosion protection. In this case various metal coatings are not reliable because of brittle inter-metallide formation. The reliable protection may be provided only up to the temperature plus 400 - 500 deg. C with the help of galvanic copper coating since

miCole, Social Media for Schools: Estudio de tecnologías para el desarrollo de aplicaciones móviles híbridas.

OpenAIRE

Bárcena Díez, Jaime

2017-01-01

El objetivo de este proyecto consiste en dar al lector una visión global sobre los diferentes tipos de aplicaciones para dispositivos móviles según su forma de desarrollo. Grado en Ingeniería Informática de Servicios y Aplicaciones

Process for enriching uranium from seawater

International Nuclear Information System (INIS)

Heitkamp, D.; Inden, P.

1982-01-01

In selective elutriation of uranium deposited on titanium oxide hydrate by carbonate solution, only uranium should be dissolved from the absorption material forming carbonate compounds, without the deposited ballast ions, above all of magnesium, calcium and sodium being elutriated. The uranium elutriation according to the invention is therefore carried out in the presence of these ballast ions in the same concentrations as those in seawater. The carbonate concentration can only be raised as far as the solubility product of the basic magnesium carbonate permits, so that magnesium remains in the solution, as well as carbonate, in the concentration present in seawater. One must accept the absence of calcium ions in the elutriation solution, as their solubility product with carbonate is considerably less than that for magnesium. (orig./PW) [de

Fluorescence spectral imaging as a tool for locating uranium deposited on surfaces - 16089

International Nuclear Information System (INIS)

Monts, David L.; Wang, Guangjun; Su, Yi; Jang, Ping-Rey; Waggoner, Charles A.

2009-01-01

In the environment, metallic uranium readily oxidizes to form uranium compounds that contain the uranyl (UO 2 +2 ) moiety. For more than a hundred and fifty years, it has been known that when illuminated with ultraviolet (UV) light, uranyl compounds exhibit characteristic fluorescence in the visible region (450-650 nm). We report our efforts to develop a transportable, quantitative Fluorescence Spectral Imaging (FSI) system as a tool for locating and quantifying uranyl compounds dispersed in soils and on other surfaces. A project is underway to develop a set of sensors to locate expended depleted uranium (DU) rounds and to process soil and debris to recover the material from domestic firing ranges. The FSI system can also be utilized to monitor excavation of DU munitions and separation of uranyl compounds from soils. FSI images are acquired by illuminating a surface with a UV light and using a narrow band pass filter on a camera, recording an image of the resulting fluorescence. The FSI image provides both spatial and spectral information. The FSI system is described and its performance characterized using field samples. (authors)

Amine synergism in uranium extraction

International Nuclear Information System (INIS)

Rinelli, G.; Abbruzzese, C.

1977-01-01

Commercial products based on C 8 to C 12 tertiary amine mixtures are now widely used in the solvent extraction of uranium from sulphuric pregnant solutions. The satisfactory results generally obtained have never required an analysis of the synergistic effects of amine combinations similar to that carried out for the organo-phosphorus compounds. In the research described the increase in the extraction power of an organic phase composed of an amine binary mixture was studied with regard to an aqueous solution from the sulphuric acid treatment of uranium ore. On the basis of the experimental results obtained, it is possible to select the best composition of the amine mixture to ensure a percentage increase in uranium recovery. Bearing in mind the tendency for the yellow-cake price to rise, the study is considered to be a useful contribution in the context of commercial products currently available on the market. (author)

Review of uranium excretion and clinical urinalysis data in accidental exposure cases

International Nuclear Information System (INIS)

Boback, M.W.

1975-01-01

This report reviews urinalysis results obtained following four incidents in which thirteen workers were exposed to high concentrations of airborne uranium. The compounds involved were U 3 O 8 , UF 6 , and uranium ore concentrates. Urine samples collected following these exposures were always analyzed for uranium, and in some cases, for specific gravity, pH, protein, sugar, white blood cells, red blood cells, and casts. Although urinary uranium concentrations exceeded 1 mg U/1, no evidence was found to indicate kidney damage as a result of these exposures

Preparation of uranium ingots from double fluorides

International Nuclear Information System (INIS)

Le Boulbin, E.

1967-05-01

A simple method has been developed for the preparation of uranium double fluorides and has given a new impetus to the study of the reduction of these compounds with a view to obtaining very pure uranium ingots. This reduction can be carried out using calcium or magnesium as the reducing agent, this latter metal being very interesting from the practical point of view. A comparative study of the heat balances of the reduction processes for the double fluorides and for uranium tetrafluoride has shown that reduction of the double fluorides is possible. The exact experimental conditions for these reductions have been determined. Our study has shown in particular that the reduction of the double salt UF 4 , CaF 2 by magnesium leads to the production of small (20 to 500 g) samples of high-purity uranium with a yield of 99 per cent. (author) [fr

Formación de usuarios de la información mediante aplicaciones Web 2.0

Directory of Open Access Journals (Sweden)

Eder Ávila Barrientos

2015-04-01

Full Text Available Objetivo: Analizar las aplicaciones web 2.0 para estimar su utilización en los programas de formación de usuarios de la información. Método: Análisis documental y la hermenéutica del discurso aplicados a los documentos impresos y digitales que abordan la temática del objeto de estudio. Resultados: se responden una serie de cuestionamientos relacionados con la integración de las aplicaciones Web 2.0 en el diseño de programas de formación de usuarios de la información. En lo que respecta a la selección de aplicaciones web 2.0, se empleo la técnica de análisis de atributos basada en las variables de uso didáctico. Concluisones: Las tecnologías de la web 2.0 y su integración en los programas de formación de usuarios de la información, representan un nicho de oportunidad para los bibliotecólogos. Una oportunidad para alcanzar el futuro y romper viejos paradigmas de la formación de usurios.

Method of converting uranium fluoride to intermediate product for uranium oxide manufacture with recycling or reusing valuable materials

International Nuclear Information System (INIS)

Baran, V.; Moltasova, J.

1982-01-01

Uranium fluoride is acted upon by water with nitrate containing a cation capable of binding fluoride ions. The uranium is extracted, for instance, with tributyl phosphate with the generated organic phase containing the prevalent proportion of uranium and representing the required intermediate product and the aqueous phase from which is isolated the fluorine component which may be used within the fuel cycle. The nitrate component of the aqueous phase is recycled following treatment. It is also possible to act on uranium fluoride directly with an aqueous solution. Here the cations of nitrate form with the fluorides soluble nondissociated complexes and reduce the concentration of free fluoride ions. The nitrate +s mostly used in an amount corresponding to its solubility in the system prior to the introduction of UF 6 . The uranium from the solution with the reduced concentration of free fluoride ions is extracted into the reaction system under such conditions as to make the prevalent majority of fluorides and an amount of uranium smaller than 5x10 -2 mol/l remain in the aqueous phase and that such an amount of fluorides should remain in the organic phase which is smaller than corresponds to the fluorine/uranium molar ratio in the organic phase. Uranium contained in the organic phase is processed into uranium oxide, with advantage into UO 2 . From the isolated compounds of fluorine and the cation of the nitrate gaseous HF is released which is used either inside or outside of the fuel cycle. (J.P.)

Analysis on uranium metallogenetic conditions of granite pluton in Ulan Uzhur

International Nuclear Information System (INIS)

Lu Yaozu

2014-01-01

Qimantage area in Qinghai province is one of the important exploration areas in the present China, Ulan Uzhur complex pluton, located in the compound tectonic magmatic belt of Qimantage, is the main cluster area with uranium mineralization. This paper describes the petrochemical, geochemical, petrophysical and Heishan uranium deposit mineralization characteristics of rocks formed at the different tectonic-magmatic cycles in Ulan Uzhur complex pluton. Uranium metallogenic conditions in Ulan Uzhur complex pluton were analyzed from uranium source, magmatic activity and structure. The research shew that the Ulan Uzhur complex pluton has the petrochemical characteristics of uranium rock and Cisuralian monzonitic granite has the most significant relationship to uranium mineralization, it has the characteristics of high background radiation, many anomalies and pronounced ore-control structure, Heishan uranium deposit was controlled by factors such as pronounced northeast and the northwest structure and alteration. To conclude, Ulan Uzhur complex pluton possesses good uranium metallogenic prospect. (author)

Aplicaciones Web para el desarrollo sostenible a través de ONG

OpenAIRE

García Miguel, Daniel

2008-01-01

La meta de este proyecto es facilitar el acceso de las ONG a la tecnología Web, y concretamente las aplicaciones Web, para que aquellas que no tengan acceso a servicios profesionales, puedan ser autosufidentes en el desarrollo de sus propias soluciones.

Gastrointestinal absorption of soluble uranium from drinking water by man

International Nuclear Information System (INIS)

Wrenn, M.E.; Singh, N.P.; Ruth, H.; Rallison, M.L.; Burleigh, D.P.

1989-01-01

The gastrointestinal absorption of uranium has been measured in ten normal healthy adult volunteers of both sexes by feeding them one litre of water containing 200 to 300 μg of uranium per litre. The water was consumed during normal daytime activities while food was also ingested at its normal rate. Complete collections of urine and faeces were made and compounded on a daily basis over a period of two weeks, one week being prior to the consumption of the uranium-containing water. Uranium was measured by radiochemical separation followed by alpha spectrometry. Both 234 U and 238 U were determined. The results on these people showed that the uptake of uranium under these conditions averaged 0.6%, well below the f 1 of 5% assumed by the ICRP. (author)

The renaissance of non-aqueous uranium chemistry

Energy Technology Data Exchange (ETDEWEB)

Liddle, Stephen T. [School of Chemistry, University of Nottingham (United Kingdom)

2015-07-20

Prior to the year 2000, non-aqueous uranium chemistry mainly involved metallocene and classical alkyl, amide, or alkoxide compounds as well as established carbene, imido, and oxo derivatives. Since then, there has been a resurgence of the area, and dramatic developments of supporting ligands and multiply bonded ligand types, small-molecule activation, and magnetism have been reported. This review (1) introduces the reader to some of the specialist theories of the area, (2) covers all-important starting materials, (3) surveys contemporary ligand classes installed at uranium, including alkyl, aryl, arene, carbene, amide, imide, nitride, alkoxide, aryloxide, and oxo compounds, (4) describes advances in the area of single-molecule magnetism, and (5) summarizes the coordination and activation of small molecules, including carbon monoxide, carbon dioxide, nitric oxide, dinitrogen, white phosphorus, and alkanes. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The utility of in vitro solubility testing in assessment of uranium exposure

International Nuclear Information System (INIS)

Eidson, A.F.; Damon, E.G.; Hahn, F.F.; Griffith, W.C. Jr.

1989-01-01

Assessment of accidental exposures in the uranium industry requires estimation of retention and excretion rates using bioassay measurements. This task is difficult if the solubility of the inhaled uranium compound is unknown. In our research, Beagle dogs were exposed to aerosols of commercial uranium milling products containing either pure ammonium diuranate (ADU) or U 3 0 8 . Dogs were exposed to ADU aerosols to achieve a median retained body burden of 0.058 mg U per kg body weight, or to U 3 0 8 aerosols to achieve a median retained body burden of 0.28 mg U per kg. A biokinetic model was applied to simulate retention and excretion of the two forms of uranium in vivo. Comparison of published in vitro dissolution data and modelling results with information from accidental human exposures showed that in vitro dissolution studies are necessary to characterise the differential solubilities of uranium compounds, and indicate the potential for kidney toxicity. Because variability in pulmonary clearance and urinary excretion rates is high among individual people, in vitro dissolution results are only marginally useful for estimating urinary excretion rates. (author)

Rapid extraction and assay of uranium from environmental surface samples

Energy Technology Data Exchange (ETDEWEB)

Barrett, Christopher A.; Chouyyok, Wilaiwan; Speakman, Robert J.; Olsen, Khris B.; Addleman, Raymond Shane

2017-10-01

Extraction methods enabling faster removal and concentration of uranium compounds for improved trace and low-level assay are demonstrated for standard surface sampling material in support of nuclear safeguards efforts, health monitoring, and other nuclear analysis applications. A key problem with the existing surface sampling swipes is the requirement for complete digestion of sample and sampling matrix. This is a time-consuming and labour-intensive process that limits laboratory throughput, elevates costs, and increases background levels. Various extraction methods are explored for their potential to quickly and efficiently remove different chemical forms of uranium from standard surface sampling material. A combination of carbonate and peroxide solutions is shown to give the most rapid and complete form of uranyl compound extraction and dissolution. This rapid extraction process is demonstrated to be compatible with standard inductive coupled plasma mass spectrometry methods for uranium isotopic assay as well as screening techniques such as x-ray fluorescence. The general approach described has application beyond uranium to other analytes of nuclear forensic interest (e.g., rare earth elements and plutonium) as well as heavy metals for environmental and industrial hygiene monitoring.

Raman Investigation of The Uranium Compounds U3O8, UF4, UH3 and UO3 under Pressure at Room Temperature

International Nuclear Information System (INIS)

Lipp, M.J.; Jenei, Z.; Park-Klepeis, J.; Evans, W.J.

2011-01-01

Our current state-of-the-art X-ray diffraction experiments are primarily sensitive to the position of the uranium atom. While the uranium - low-Z element bond (such as U-H or U-F) changes under pressure and temperature the X-ray diffraction investigations do not reveal information about the bonding or the stoichiometry. Questions that can be answered by Raman spectroscopy are (i) whether the bonding strength changes under pressure, as observed by either blue- or red-shifted peaks of the Raman active bands in the spectrum and (ii) whether the low-Z element will eventually be liberated and leave the host lattice, i.e. do the fluorine, oxygen, or hydrogen atoms form dimers after breaking the bond to the uranium atom. Therefore Raman spectra were also collected in the range where those decomposition products would appear. Raman is particularly well suited to these types of investigations due to its sensitivity to trace amounts of materials. One challenge for Raman investigations of the uranium compounds is that they are opaque to visible light. They absorb the incoming radiation and quickly heat up to the point of decomposition. This has been dealt with in the past by keeping the incoming laser power to very low levels on the tens of milliWatt range consequently affecting signal to noise. Recent modern investigations also used very small laser spot sizes (micrometer range) but ran again into the problem of heating and chemical sensitivity to the environment. In the studies presented here (in contrast to all other studies that were performed at ambient conditions only) we employ micro-Raman spectroscopy of samples situated in a diamond anvil cell. This increases the trustworthiness of the obtained data in several key-aspects: (a) We surrounded the samples in the DAC with neon as a pressure transmitting medium, a noble gas that is absolutely chemically inert. (b) Through the medium the sample is thermally heat sunk to the diamond anvils, diamond of course possessing the

Initial process development for uranium bioprecipitation

International Nuclear Information System (INIS)

Truex, M.; Peyton, B.; Gorby, Y.; Valentine, N.

1994-01-01

Some bacteria can destabilize soluble metal complexes by enzymatically reducing the metal to a valence state where insoluble compounds are formed. For instance, oxidized uranium (VI) is highly soluble, but it precipitates from solution as the U(IV) oxide uraninite after microbial reduction. The advantage of this technology is that the uranium is easily separated from the aqueous phase, resulting in a small volume of relatively pure uraninite waste. A dissimilatory iron-reducing bacterium capable of uranium reduction was found to have a maximum growth rate of 0.142/hr, a Monod half-saturation constant of 3.4 mg/L, and a cellular yield of 0.071 mg-biomass/mg-iron for iron reduction at 30 C and pH 6.8. The kinetics of iron reduction were used to predict the performance of several reactor configurations for reduction of metals of interest such as uranium. A stirred-tank reactor in series with a plug-flow reactor was determined to be the best configuration for application of the bioprecipitation technology in a continuous-flow process

Compared biokinetic and biological studies of chronic and acute inhalations of uranium compounds in the rat

International Nuclear Information System (INIS)

Monleau, M.

2005-12-01

Uranium is a natural, radioactive heavy metal, widely used in the nuclear industry in various chemical and isotopic forms. Its use in the fuel cycle involves the risk of radiological exposure for the workers, mainly via the inhalation of uranium particles. According to the workplace configuration, uranium contaminations can be acute or repeated, involve various chemical forms and different levels of enrichment, as well as involving one or several components. The dosimetric concepts and models available for workers' radiological protection, as well as most of the studies of the biological effects, correspond to acute exposure situations. Moreover the processes leading to pathological effects are little known in vivo. In this context, the main question is to know whether exposures due to repeated inhalation by rats induce the element kinetics and toxicity, which may be different from those observed after an acute exposure. In this study, comparison of the experimental and theoretical biokinetics of an insoluble uranium repeatedly inhaled over three weeks shows that a chronic contamination is correctly modelled, except for bone retention, by the sum of acute, successive and independent incorporations. Moreover, the kinetics of a soluble uranium inhaled irregularly can be modified by previous repeated exposure to an insoluble uranium. In certain cases therefore, exposure to uranium could modify its biokinetics during later exposures. At a toxicological level, the study demonstrates that the uranium particles inhaled repeatedly induce behavioural disruptions and genotoxic effects resulting in various sorts of DNA damage, in several cell types and certainly depending on the quantity inhaled. Exposures involving several uraniferous components produce a synergy effect. Moreover, repeated inhalations worsen the genotoxic effects in comparison to an acute exposure. This work demonstrates the importance of not ignoring the effects of the repetition of uranium exposure. It

Gestión de organizaciones: enfoques y aplicaciones

OpenAIRE

Zárate, Rodrigo; Argüelles Pabón, Denise Caroline; Aparicio García, Santiago; Largacha Martínez, Carlos; Pérez Uribe, Rafael; de la Hoz, Gerardo A.

2013-01-01

Una buena gestión puede transformar una organización. El libro Gestion de organizaciones enfoques y aplicaciones, realiza un análisis de todos los aspectos relevantes que llevan a una organización a generar nuevas y mejores prácticas para el impulso de su productividad y competitividad. se estudian diferentes modelos de gestión con el fin de potencializar el aprendizaje organizacional, es decir la gestión del conocimiento, del talento y la gestión por competencias....

Molybdenum from uranium solutions

International Nuclear Information System (INIS)

Gardner, H.E.

1981-01-01

A method of removing molybdenum from a uranium bearing solution is claimed. It comprises adding sufficient reactive lead compound to supply at least 90 percent of the stoichiometric quantity of lead ion required to fully react with the molybdenum present to form insoluble lead molybdate and continuing the reaction with agitation until the desired percentage of the molybdenum present has reacted with the lead ion

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 process until the obtention of uranium rich concentrate are described. The purification steps of uranium compounds to nuclear purity material are described as well as the steps to elaborate metal of which the purity grade will be specify. Finally, the economic aspects of uranium production difficulty will be considered in relation with technical progresses which we can expect to achieve in the future. (M.P.)

Phase equilibrium study on system uranium-plutonium-tungsten-carbon

International Nuclear Information System (INIS)

Ugajin, Mitsuhiro

1976-11-01

Metallurgical properties of the U-Pu-W-C system have been studied with emphasis on phases and reactions. Free energy of compound formation, carbon activity and U/Pu segregation in the W-doped carbide fuel are estimated using phase diagram data. The results indicate that tungsten metal is useful as a thermochemical stabilizer of the carbide fuel. Tungsten has high temperature stability in contact with uranium carbide and mixed uranium-plutonium carbide. (auth.)

Desarrollo de aplicaciones móviles bajo la plataforma de Iphone

Directory of Open Access Journals (Sweden)

Karen Melissa Rojas Lizarazo

2012-05-01

Full Text Available El iPhone es un dispositivo móvil que lleva cerca de cinco años en el mercado de celulares, y sus funciones van más allá del uso como tal de un teléfono celular, gracias al App Store, que ofrece miles de aplicaciones creadas por desarrolladores alrededor del mundo. La arquitectura y el sistema operativo del iPhone permiten que las aplicaciones creadas por desarrolladores usen tecnologías especializadas para diferentes tipos de usuarios, permitiendo incluir características como gráficos de alta definición o usar accesorios de hardware, haciendo uso de los frameworks soportados por la arquitectura del dispositivo; todo esto es posible crearlo gracias a las herramientas de desarrollo provistas por Apple. El almacenamiento y la persistencia de datos se ven plasmados en el desarrollo de una aplicación caso de estudio que hace uso de Core Data para el manejo de la información.

A melt refining method for uranium-contaminated aluminum

International Nuclear Information System (INIS)

Uda, T.; Iba, H.; Hanawa, K.

1986-01-01

Melt refining of uranium-contaminated aluminum which has been difficult to decontaminate because of the high reactivity of aluminum, was experimentally studied. Samples of contaminated aluminum and its alloys were melted after adding various halide fluxes at various melting temperatures and various melting times. Uranium concentration in the resulting ingots was determined. Effective flux compositions were mixtures of chlorides and fluorides, such as LiF, KCl, and BaCl 2 , at a fluoride/chloride mole ratio of 1 to 1.5. The removal of uranium from aluminum (the ''decontamination effect'') increased with decreasing melting temperature, but the time allowed for reaction had little influence. Pure aluminum was difficult to decontaminate from uranium; however, uranium could be removed from alloys containing magnesium. This was because the activity of the aluminum was decreased by formation of the intermetallic compound Al-Mg. With a flux of LiF-KCl-BaCl 2 and a temperature of 800 0 C, uranium added to give an initial concentration of 500 ppm was removed from a commercial alloy of aluminum, A5056, which contains 5% magnesium, to a final concentration of 0.6 ppm, which is near that in the initial aluminum alloy

DESCRIPCIÓN DE UN FRAMEWORK METODOLOGICO PARA EL DESARROLLO DE APLICACIONES RELACIONADAS CON EL PATRIMONIO CULTURAL

Directory of Open Access Journals (Sweden)

Edwin Mauricio Hincapié-Montoya

2014-01-01

Full Text Available Preservar los espacios y difundirlos es una función social que debe mantener unidos a los pueblos y que no puede dejarse a un lado por el clamor y la voz del desarrollo. Para ello la tecnología juega un papel de facilitador mediático a través de la cual se puede llegar a diferentes espacios y lugares históricamente importantes pero físicamente inaccesibles por su desaparición. En los últimos años se han desarrollado aplicaciones que buscan reactivar el patrimonio cultural y hacen uso de tecnologías como realidad virtual, realidad aumentada o juegos serios. Sin embargo, la mayoría son casos de estudio en un tema particular y el área carece de un framework metodológico, que guie y facilite el desarrollo de este tipo de aplicaciones. En este articulo proponemos un framework metodológico conceptual, el cual busca guiar el desarrollo de aplicaciones relacionadas con la reactivación del patrimonio cultural al tiempo que maximiza el aprendizaje de los usuarios en este tema.

Un modelo de coordinación cliente-servidor, de apoyo a la construcción de aplicaciones colaborativas portables

OpenAIRE

Ochoa, Sergio; Fuller, David A.

2001-01-01

En la actualidad existe una gran variedad de plataformas de apoyo al desarrollo de aplicaciones colaborativas, que trabajan bajo una arquitectura cliente-servidor [Chabert 98, Guerrero 98, Licea 98, Trevor 97]. Estas poseen un alto grado de incompatibilidad entre ellas, lo cual produce una fuerte dependencia de la aplicación cliente, hacia el servidor usado. Debido a esto, las capacidades de las aplicaciones están sometidas a la funcionalidad permitida por el servidor. Esto entorpece el avanc...

The crystal chemistry of novel thorium and uranium compounds with oxo-anions from group VI of periodic table (S, Se, Te, Cr, Mo and W)

Energy Technology Data Exchange (ETDEWEB)

Xiao, Bin

2016-01-26

This dissertation focus on the synthesis, phase studies and physicochemical properties of novel thorium and uranium compounds with the Group VI (S, Se, Te, Cr, Mo, W) of the Periodic Table. All the studied compounds are listed in Table 2.2 from the page 15. I subdivided all the newly synthesized compounds into several chapters according to their structural and topological differences. First, for thorium molybdates and tungstates, almost all of these compounds are based on corner-sharing of ThO{sub x} (x = 6, 8 and 9) and MoO{sub 4} or WO{sub x} (x = 4, 5, 6) polyhedra. Interestingly, all these compounds can be seen as derived from a pure thorium molybdate compound (ThMo{sub 2}O{sub 8}) which was isolated from high-temperature solid-state synthesis method. Therefore, the polymorphs of this most basic ThMo{sub 2}O{sub 8} compound is firstly introduced (see Chapter 3.1 from page 18). The thermodynamic, electronic and vibrational properties of all investigated ThMo{sub 2}O{sub 8} polymorphs were studied using ab initio calculations. Then, two subfamilies of thorium molybdates, that is, rubidium thorium molybdate and cesium thorium molybdate and their thermal and vibrational behaviors were discussed in details in Chapter 4.1 from page 37 and Chapter 4.2 from page 50, respectively. Moreover, some new insights about the complexity of thorium tungstates were also discussed (Chapter 4.3 from page 59). Some novel thorium molybdate and chromate compounds synthesized from aqueous condition are discussed in Chapter 5 from page 71. In the Chapter 8.2.4, the stereochemistry for thorium and uranium compounds are introduced, especially thorium selinites and uranyl tellurites (see Chapter 6.1 from page 82), thorium tellurites (Chapter 6.2 from page 93), and uranyl tellurites (Chapter 6.3 from page 99 for sodium uranyl tellurium and Chapter 6.4 from page 110 for potassium uranyl tellurium, respectively). In the actinide tellurium systems, additional MoO{sub 3}/WO{sub 3} were also

Fluor determination by alkaline hydrolysis of the uranium and thorium fluorides

International Nuclear Information System (INIS)

Barrachina Gomez, L.; Gasco Sanchez, L.

1961-01-01

The alkaline hydrolysis of the uranium and thorium fluorides is studded and a new method for the determination of the fluoride, on the basis of a indirect volumetric titration with standard soda, is proposed. The compounds that may influence the hydrolysis of the uranium fluoride and that may be occasionally found in it as impurities are also studied. the method can be applied to the uranium fluoride except when there is a great quantity of F 2 UO 2 or UO 3 present in the sample. (Author) 20 refs

Uranium-mediated electrocatalytic dihydrogen production from water

Science.gov (United States)

Halter, Dominik P.; Heinemann, Frank W.; Bachmann, Julien; Meyer, Karsten

2016-02-01

Depleted uranium is a mildly radioactive waste product that is stockpiled worldwide. The chemical reactivity of uranium complexes is well documented, including the stoichiometric activation of small molecules of biological and industrial interest such as H2O, CO2, CO, or N2 (refs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11), but catalytic transformations with actinides remain underexplored in comparison to transition-metal catalysis. For reduction of water to H2, complexes of low-valent uranium show the highest potential, but are known to react violently and uncontrollably forming stable bridging oxo or uranyl species. As a result, only a few oxidations of uranium with water have been reported so far; all stoichiometric. Catalytic H2 production, however, requires the reductive recovery of the catalyst via a challenging cleavage of the uranium-bound oxygen-containing ligand. Here we report the electrocatalytic water reduction observed with a trisaryloxide U(III) complex [((Ad,MeArO)3mes)U] (refs 18 and 19)—the first homogeneous uranium catalyst for H2 production from H2O. The catalytic cycle involves rare terminal U(IV)-OH and U(V)=O complexes, which have been isolated, characterized, and proven to be integral parts of the catalytic mechanism. The recognition of uranium compounds as potentially useful catalysts suggests new applications for such light actinides. The development of uranium-based catalysts provides new perspectives on nuclear waste management strategies, by suggesting that mildly radioactive depleted uranium—an abundant waste product of the nuclear power industry—could be a valuable resource.

Uranium extraction from gold-uranium ores

Energy Technology Data Exchange (ETDEWEB)

Laskorin, B.N.; Golynko, Z.Sh.

1981-01-01

The process of uranium extraction from gold-uranium ores in the South Africa is considered. Flowsheets of reprocessing gold-uranium conglomerates, pile processing and uranium extraction from the ores are presented. Continuous counter flow ion-exchange process of uranium extraction using strong-active or weak-active resins is noted to be the most perspective and economical one. The ion-exchange uranium separation with the succeeding extraction is also the perspective one.

DEVELOPMENT OF HIGH-DENSITY U/AL DISPERSION PLATES FOR MO-99 PRODUCTION USING ATOMIZED URANIUM POWDER

Directory of Open Access Journals (Sweden)

HO JIN RYU

2013-12-01

Full Text Available Uranium metal particle dispersion plates have been proposed as targets for Molybdenum-99 (Mo-99 production to improve the radioisotope production efficiency of conventional low enriched uranium targets. In this study, uranium powder was produced by centrifugal atomization, and miniature target plates containing uranium particles in an aluminum matrix with uranium densities up to 9 g-U/cm3 were fabricated. Additional heat treatment was applied to convert the uranium particles into UAlx compounds by a chemical reaction of the uranium particles and aluminum matrix. Thus, these target plates can be treated with the same alkaline dissolution process that is used for conventional UAlx dispersion targets, while increasing the uranium density in the target plates

Determination of the impurities Al, Mn, Fe, Ni, Cu and Zn in nuclear grade uranium by ICP-OES

Energy Technology Data Exchange (ETDEWEB)

Kakazu, Mauricio H.; Cotrim, Marycel E.B.; Silva, Douglas B. da; Pires, Maria Aparecida F., E-mail: mhkakazu@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

Uranium compounds are specially produced for use in nuclear reactors and must meet strict physical and chemicals specifications. The current study discusses the separation of Al, Mn, Fe, Ni, Cu and Zn from uranium compounds and their quantitative determination using inductively coupled plasma optical emission spectrometry. To avoid interference effect caused by uranium in the spectroscopic emission lines of elements of interest, the chromatographic behavior of TBP impregnated macroporous Amberlite XAD-4 column was investigated. The break through curves of uranium obtained showed maximum retention of up to 11 grams of uranium and the elution curves for the elements showed reproducible recovery rate of 90% on 50 mL elution. Synthetic samples of nuclear grade uranium prepared with the addition of 250 {mu}g/g of U of the above individual elements were used to verify the performance of the method. The method showed a recovery rate of 80 to 90% for the elements under study. (author)

Determination of the impurities Al, Mn, Fe, Ni, Cu and Zn in nuclear grade uranium by ICP-OES

International Nuclear Information System (INIS)

Kakazu, Mauricio H.; Cotrim, Marycel E.B.; Silva, Douglas B. da; Pires, Maria Aparecida F.

2011-01-01

Uranium compounds are specially produced for use in nuclear reactors and must meet strict physical and chemicals specifications. The current study discusses the separation of Al, Mn, Fe, Ni, Cu and Zn from uranium compounds and their quantitative determination using inductively coupled plasma optical emission spectrometry. To avoid interference effect caused by uranium in the spectroscopic emission lines of elements of interest, the chromatographic behavior of TBP impregnated macroporous Amberlite XAD-4 column was investigated. The break through curves of uranium obtained showed maximum retention of up to 11 grams of uranium and the elution curves for the elements showed reproducible recovery rate of 90% on 50 mL elution. Synthetic samples of nuclear grade uranium prepared with the addition of 250 μg/g of U of the above individual elements were used to verify the performance of the method. The method showed a recovery rate of 80 to 90% for the elements under study. (author)

Following the electroreduction of uranium dioxide to uranium in LiCl–KCl eutectic in situ using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Brown, L.D.; Abdulaziz, R.; Jervis, R.; Bharath, V.J. [Electrochemical Innovation Lab, Dept. Chemical Engineering, UCL, London WC1E 7JE (United Kingdom); Atwood, R.C.; Reinhard, C.; Connor, L.D. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Simons, S.J.R.; Inman, D.; Brett, D.J.L. [Electrochemical Innovation Lab, Dept. Chemical Engineering, UCL, London WC1E 7JE (United Kingdom); Shearing, P.R., E-mail: p.shearing@ucl.ac.uk [Electrochemical Innovation Lab, Dept. Chemical Engineering, UCL, London WC1E 7JE (United Kingdom)

2015-09-15

Highlights: • We investigated the electroreduction of UO{sub 2} to U in LiCl/KCL eutectic molten salt. • Combined electrochemical measurement and in situ XRD is utilised. • The electroreduction appears to occur in a single, 4-electron-step, process. • No intermediate compounds were observed. - Abstract: The electrochemical reduction of uranium dioxide to metallic uranium has been investigated in lithium chloride–potassium chloride eutectic molten salt. Laboratory based electrochemical studies have been coupled with in situ energy dispersive X-ray diffraction, for the first time, to deduce the reduction pathway. No intermediate phases were identified using the X-ray diffraction before, during or after electroreduction to form α-uranium. This suggests that the electrochemical reduction occurs via a single, 4-electron-step, process. The rate of formation of α-uranium is seen to decrease during electrolysis and could be a result of a build-up of oxygen anions in the molten salt. Slow transport of O{sup 2−} ions away from the UO{sub 2} working electrode could impede the electrochemical reduction.

Seven-co-ordination in chlorohexakis(trimethylphosphine oxide)- uranium(IV) trichloride: crystal and molecular structure

Energy Technology Data Exchange (ETDEWEB)

Bombieri, G; Forsellini, E [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Brown, D; Whittaker, B

1976-01-01

The structure of the title compound has been determined by single-crystal X-ray diffraction methods from diffractometer data and refined to a final R of 0.023. The compound crystallises in space group R3c with asub(hex) = 18.447(3), csub(hex) = 19.348(3) A, Z = 6. The uranium atom is co-ordinated to one chlorine (U-Cl 2.813 A) and six oxygen atoms (mean U-O 2.26 A); the co-ordination polyhedron can be described as a distorted monocapped trigonal antiprism or as a distorted monocapped octahedron. The anionic chlorines are more than 6.22 A from the uranium atoms. The results are discussed in relation to spectral data for this and related uranium(IV) complexes.

Seven-co-ordination in chlorohexakis(trimethylphosphine oxide)- uranium(IV) trichloride: crystal and molecular structure

International Nuclear Information System (INIS)

Bombieri, G.; Forsellini, E.; Brown, D.; Whittaker, B.

1976-01-01

The structure of the title compound has been determined by single-crystal X-ray diffraction methods from diffractometer data and refined to a final R of 0.023. The compound crystallises in space group R3c with asub(hex) = 18.447(3), csub(hex) = 19.348(3) A, Z = 6. The uranium atom is co-ordinated to one chlorine (U-Cl 2.813 A) and six oxygen atoms (mean U-O 2.26 A); the co-ordination polyhedron can be described as a distorted monocapped trigonal antiprism or as a distorted monocapped octahedron. The anionic chlorines are more than 6.22 A from the uranium atoms. The results are discussed in relation to spectral data for this and related uranium(IV) complexes. (author)

Method for converting uranium oxides to uranium metal

International Nuclear Information System (INIS)

Duerksen, W.K.

1988-01-01

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

Options for disposal and reapplication of depleted uranium hexafluoride

International Nuclear Information System (INIS)

Fitch, St.H.

2009-01-01

The nuclear renaissance has spurred the need to enrich uranium to fuel power reactors to meet the nation's energy requirements. However, enriching uranium produces the volatile byproduct of DUF 6 tails. In an ambient environment, DUF 6 decomposes into uranium oxides and hydrogen fluoride (HF). This HF component makes DUF 6 unsuitable for disposal as low-level waste. To make DUF 6 suitable for disposal, it must be stabilized in a controlled process by converting it into uranium oxides and fluorine compounds by the processes of de-conversion and fluorine extraction. Once stabilized, the DU and fluorine have reapplication potential that would delay or divert the need for disposal. Certain challenges confound this process, notably the chemical toxicity from elemental fluorine and DU, radiation hazards, limited low-level waste disposal capacity, and potential political and public opposition. (authors)

Risk assessment applications for determining cleanup limits for uranium in treated and untreated soils

International Nuclear Information System (INIS)

Armstrong, A.Q.; Layton, D.W.; Rutz, E.E.

1994-01-01

Uranium-contaminated soils are present at various locations across the US where uranium was processed for nuclear fuels or atomic weapons. Important issues relative to such contamination include the assessment of potential health risks associated with human exposures to the residual uranium and the determination of safe levels of uranium in soils that have been treated by a given technology. This paper discusses various risk assessment considerations that must be dealt with when developing cleanup limits for uranium in treated and untreated soils. Key issues addressed include alternative land use scenarios, potential exposure pathways, characterization of the bioavailability of uranium compounds in food and water, a brief overview of health risks associated with uranium and its daughter products as well as a summary of considerations for development of risk-based cleanup limits for uranium in soils

Activation of chalcogens and chalcogenides at reactive uranium centers

Energy Technology Data Exchange (ETDEWEB)

Franke, Michael Sebastian

2015-07-23

The high reactivity of many trivalent uranium complexes was investigated in the Meyer group, however, these studies were not limited to small-molecule activation, but were extended to other relatively inert reagents like the heavier elemental chalcogens sulfur, selenium, and tellurium. The tripodal N-anchored chelate ({sup Ad,Me}ArO){sub 3}N{sup 3-} (trianion of tris(3-Adamantyl-2-hydroxy-5-methylbenzyl)amine) was found to be a very suitable candidate for this task and the respective uranium(III) complex [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)] is able to activate elemental sulfur and selenium to form the dinuclear, chalcogenido-bridged complexes [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-E)] (E = S, Se). Starting from this previously accomplished work, research in this thesis aimed at furthering reactivity studies of trivalent [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)], but also its chalcogenido-bridged uranium(IV) products, and the spectroscopic characterization of all newly synthesized compounds. Furthermore, the development of the new phenol HOAr* (Ar* = 2,6-(CHPh{sub 2}){sub 2}-4-Me-C{sub 6}H{sub 2}, 2,6-bis(diphenylmethyl)-4-methylphenyl) and its establishment as a ligand to be used for uranium coordination chemistry was another goal of this thesis. The activation of CO{sub 2} by uranium(III) complex [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)] to yield the dinuclear, carbonate-bridged uranium(IV/IV) complex [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-κ{sup 1}:κ{sup 2}-CO{sub 3})] and CO was reported in 2010 by Meyer and co-workers. These previous results led to the pursuit of the isolation of mixed chalcogenocarbonate complexes from the reaction of the bridging chalcogenidos [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-E)] (E = S, Se) with either CO{sub 2} or its heterocumulene analogs COS or CS{sub 2}. The chalcogeno-carbonates [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-κ{sup 1}:κ{sup 2}-CO{sub 2}E)] und [{(("A"d","M"eArO)_3N)U"I"V-(DME)}{sub 2}(�

Uranium problem in production of wet phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Gorecka, H; Gorecki, H [Politechnika Wroclawska (Poland)

1980-01-01

The balance of the uranium in the wet dihydrate method was presented. This balance shows that a large quantity of the uranium compounds shift from mineral phosphate rock to liquid phase of decomposition pulp (about 70-85% U) and the rest moves to phosphogypsum (about 15-25% U). The contents of uranium in phosphate rock imported for our country and in products and by-products of the fertilizer industry, were determined. Concentration of uranium in the phosphogypsum is dependent on the type of mineral rock and the process of phosphogypsum crystallization. Analysis of the uranium contents in phosphogypsum samples and results of the sedimentation analysis indicated influence of the specific surface of phosphogypsum crystals on the uranium concentration. Investigation of the sets of samples obtained in the industrial plant proved that phosphogypsum cake washed counter-currently on the filter contained from 10 to 20 ..mu..g U/g. The radioactivity of these samples fluctuated from 35 to 60 pCi/g. Using solution sulphuric acid of concentration in range 2-4% by weight H/sub 2/SO/sub 4/ to washing and repulpation of the phosphogypsum enables to reduce its radioactivity to level below 25 pCi/g. This processing makes possible to utilize this waste material in the building industry. Extraction of uranium from the wet phosphoric acid using kerosen solution of the reaction product between octanol -1 and phosphorus pentaoxide showed possibility to recover over 80% of uranium contained in phosphate rock.

Preparation of uranium ingots from double fluorides; Elaboration de lingots d'uranium a partir de fluorures doubles

Energy Technology Data Exchange (ETDEWEB)

Le Boulbin, E [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-05-15

A simple method has been developed for the preparation of uranium double fluorides and has given a new impetus to the study of the reduction of these compounds with a view to obtaining very pure uranium ingots. This reduction can be carried out using calcium or magnesium as the reducing agent, this latter metal being very interesting from the practical point of view. A comparative study of the heat balances of the reduction processes for the double fluorides and for uranium tetrafluoride has shown that reduction of the double fluorides is possible. The exact experimental conditions for these reductions have been determined. Our study has shown in particular that the reduction of the double salt UF{sub 4}, CaF{sub 2} by magnesium leads to the production of small (20 to 500 g) samples of high-purity uranium with a yield of 99 per cent. (author) [French] La mise au point d'une methode simple de preparation de fluorures doubles d'uranium a remis a l'ordre du jour la reduction de ces composes en vue d'obtenir des lingots d'uranium tres pur. Cette reduction peut etre conduite en utilisant du calcium ou du magnesium comme reducteur, ce dernier metal etant tres interessant du point de vue pratique. Une etude comparative des bilans thermiques des reductions des fluorures doubles et du tetrafluorure d'uranium a montre que la reduction des fluorures doubles etait possible. Les conditions experimentales precises de ces reductions ont ete determinees. Notre etude a montre, en particulier, que la reduction du sel double UF{sub 4}, F{sub 2}Ca par le magnesium permet d'obtenir sur des petites quantites de 20 a 500 g, de l'uranium de haute purete avec un rendement de 99 pour cent. (auteur)

Nonaqueous chlorination of uranium metal in tributyl phosphate

International Nuclear Information System (INIS)

Buchikhin, E.P.; Kuznetsov, A.Yu.; Shatalov, V.V.; Vidanov, V.L.; Chekmarev, A.M.

2005-01-01

Low-temperature (30-50 deg C) chlorination of uranium metal in the TBP-TCE-Cl 2 system (TCE = tetrachloroethylene) was studied. Dissolution of uranium in the dipolar aprotic solvent proceeds with formation of U(IV) compounds. The activation energy of this process is 31.24 kJ mol -1 , and relative reaction order with respect to Cl 2 is 2. The effect of TBP concentration on chlorination was examined. The chlorination rate sharply increases at a water content in the TBP-TCE system of 0.2- 0.6 vol % [ru

Laser based analytical spectroscopy of uranium

International Nuclear Information System (INIS)

Argekar, A.A.; Kulkarni, M.J.; Godbole, S.V.; Page, A.G.; Samuel, J.K.; Paranjape, D.B.; Singh Mudher, K.D.

1992-01-01

Analytical spectroscopy of uranium has been studied using a XeCl excimer laser, using the fluorescence emission of U(VI) ions doped in a solid solution of sodium fluoride (NaF) and sodium chloride (NaCl) in 3:2 proportion. An electronic circuitry involving time-gating of the photomultiplier tube and facility to integrate the analytical signal over ten laser pulses has been developed to enable laser operation and signal detection with high S/N ratio. The matrix enhanced U(VI) fluorescence emission is free from chemical and spectral interferences due to the concomitant presence of ten metallic elements generally associated with uranium. The digital signal output is highly precise and does not saturate upto 5 ppm uranium concentration. X-ray diffraction patterns obtained for uranium doped compounds at 2.5% and 10% dopant concentrations are broadly similar to that of Na 2 U 2 O 7 . The detailed studies have, however, revealed fine structure for individual peaks, thereby, revealing the formation of sodium fluoro-uranate complex which is responsible for the enhanced intensity of fluorescence emission. (author). 10 refs., 6 figs., 2 tabs

Protection of uranium by metallic coatings

International Nuclear Information System (INIS)

Baque, P.; Koch, P.; Dominget, R.; Darras, R.

1968-01-01

A study is made of the possibilities of inhibiting or limiting, by means of protective metallic coatings, the oxidation of uranium by carbon dioxide at high temperature. In general, surface films containing intermetallic compounds or solid solutions of uranium with aluminium, zirconium, copper, niobium, nickel or chromium are formed, according to the techniques employed which are described here. The processes most to be recommended are those of direct diffusion starting from a thin sheet or tube, of vacuum deposition, or of immersion in a molten bath of suitable composition. The conditions for preparing these coatings have been optimized as a function of the protective effect obtained in carbon dioxide at 450 or at 500 C. Only the aluminium and zirconium based coatings are really satisfactory since they can lead to a reduction by a factor of 5 to 10 in the oxidation rate of uranium in the conditions considered; they make it possible in particular to avoid or to reduce to a very large extent the liberation of powdered oxide. Furthermore, the coatings produced generally give the uranium good protection against atmospheric corrosion. (author) [fr

Cerium compounds in the fashion of the light actinides

International Nuclear Information System (INIS)

Koelling, D.D.

1984-01-01

Researchers familiar with the light actinides easily recognize in cerium compounds a microcosm of the rich variety of properties seen in the light actinides. The parallelism seen between comparable cerium and actinide compounds strongly suggests that the same physical models are applicable. The most significant is the relative size of the f-orbital. Localization is generally tighter in Ce compounds than uranium compounds, making Ce roughly analogous to Np through Am. A way to see the actinide parallelism is to compare Hill plots. Compounds in the different regions of the plots (representing different physics) are isostructural compounds with the same companion (B) elements. The most common materials exhibiting a direct f-f interaction are the cubic Laves compounds. Accordingly, we have determined the band structures of CeRu 2 , CeRh 2 , CeIr 2 , CeOs 2 , and CeNi 2 . Compounds illustrative of the interaction of f-orbitals with ligand orbitals are the Cu 3 Au structured materials. Materials calculated in this class are CeRh 3 , CePd 3 , and CeSn 3 - the materials of much interest as mixed valent. Although the focus is on the Ce compounds, calculations performed on uranium isomorphs are used to highlight the interesting physics

Method for converting uranium oxides to uranium metal

Science.gov (United States)

Duerksen, Walter K.

1988-01-01

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

Various electroanalytical methods for the determination of uranium in different matrices

Directory of Open Access Journals (Sweden)

Alankar Shrivastava

2013-06-01

Full Text Available Uranium is a toxic material hence numerous body systems such as the kidney, brain, liver, and heart can be affected by uranium exposure. The main effect is kidney toxicity. Uranium is a naturally occurring element found in low levels in all rock, soil, and water. All uranium isotopes may also cause radiation hazards, thus without any doubt an analysis of such materials in the surrounding environment is very important. The presented review is a summarization of all electroanalytical techniques for the determination of uranium and its compounds in various matrices. Totally 43 different methods are found in our literature survey. Out of these three are polarographic, 25 potentiometry, five capillary electrophoresis and 28 voltametric methods are available in the literature. Interferences of different ions and applications in different matrices are also given for each method.

Framework Orientado a Aspectos de Recopilación Automática de Datos para la Evolución de Usabilidad en Aplicaciones Web

Directory of Open Access Journals (Sweden)

Roberto Farias

2016-08-01

Full Text Available La Usabilidad consiste de un conjunto de atributos que permiten evaluar el esfuerzo que deberá invertir un usuario para realizar una tarea determinada a través de la utilización de un software específico. En este sentido, una aplicación se considerará más usable cuanto menos esfuerzo requiera para su utilización. En la actualidad, la World Wide Web, se ha constituido como un enorme repositorio de información que es presentada y puesta a disposición de los usuarios a través de diversos sitios o páginas web cuya finalidad es promover el acceso a la información y de esta manera,  garantizar la igualdad de oportunidades a quienes la consumen. Por otro lado, la evolución de las tecnologías que le dan soporte, la han convertido en una plataforma tecnológica sobre la cual es posible desarrollar aplicaciones con un nivel de interacción y funcionalidad similar al de las aplicaciones de escritorio (WIMP. Existen una gran variedad de trabajos sobre usabilidad web, centrados principalmente en aspectos tales como la navegación y la arquitectura de información de los sitios o páginas web. Sin embargo, la usabilidad de las aplicaciones web, que experimentan un alto grado de interacción con el usuario (action-oriented similar al de las aplicaciones de escritorio, no puede ser evaluadas de la misma manera que en un sitio web (information-oriented donde la interacción con el usuario es escasa y limitada. Si bien pueden encontrarse una diversidad de trabajos que tratan como objeto de estudio a la usabilidad en aplicaciones, en entornos de escritorio ó moviles, no se han reconocido trabajos referidos a la usabilidad de aplicaciones en entornos web. En este trabajo, se propone un framework basado en AOP, capaz de dar soporte al proceso de evaluación de usabilidad, en aplicaciones web, durante la ejecución de tareas de usuario.

Lattice anisotropy in uranium ternary compounds: UTX

International Nuclear Information System (INIS)

Mašková, S.; Adamska, A.M.; Havela, L.; Kim-Ngan, N.-T.H.; Przewoźnik, J.; Daniš, S.; Kothapalli, K.; Kolomiets, A.V.; Heathman, S.; Nakotte, H.; Bordallo, H.

2012-01-01

Highlights: ► Compressibility and thermal expansion of several U-based compounds were established. ► The direction of the U–U bonds is the “soft” crystallographic direction. ► Highest coefficient of linear thermal expansion is in the direction of the U–U bonds. ► The closer the U atoms are together the better they can be compressed together. - Abstract: Several U-based intermetallic compounds (UCoGe, UNiGe with the TiNiSi structure type and UNiAl with the ZrNiAl structure type) and their hydrides were studied from the point of view of compressibility and thermal expansion. Confronted with existing data for the compounds with the ZrNiAl structure type a common pattern emerges. The direction of the U–U bonds with participation of the 5f states is distinctly the “soft” crystallographic direction, exhibiting also the highest coefficient of linear thermal expansion. The finding leads to an apparent paradox: the closer the U atoms are together in a particular direction the better they can be additionally compressed together by applied hydrostatic pressure.

Uranium(VI) transport modeling: geochemical data and submodels

International Nuclear Information System (INIS)

Tripathi, V.S.

1984-01-01

Understanding the geochemical mobility of U(VI) and modeling its transport is important in several contexts including ore genesis, uranium exploration, nuclear and mill-tailings waste management, and solution mining of uranium ores. Adsorption is a major control on partitioning of solutes at the mineral/solution interface. The effect of carbonate, fluoride, and phosphate complexing on adsorption of uranium was investigated. A critical compilation of stability constants of inorganic complexes and solid compounds of U(VI) necessary for proper design of experiment and for modeling transport of uranium was prepared. The general features of U(VI) adsorption in ligand-free systems are similar to those characteristic of other hydrolyzable metal ions. The adsorption processes studied were found to be reversible. The adsorption model developed in ligand-free systems, when solution complexing is taken into account, proved remarkably successful in describing adsorption of uranium in the presence of carbonate and fluoride. The presence of phosphate caused a much smaller decrease in the extent of adsorption than expected; however, a critical reassessment of the stability of UO 2 2+ .HPO 4 2- complexes, showed that phosphato complexes, if any, are extremely weak under experimental conditions. Removal of uranium may have occurred due to precipitation of sodium uranyl phosphates in addition to adsorption

Uranium dioxide calcining apparatus and method

International Nuclear Information System (INIS)

Cole, E.A.; Peterson, R.S.

1978-01-01

This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO 2 ) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO 2 , means for cooling the UO 2 to a temperature of below 100 0 C and conveying the cooled UO 2 to storage or to subsequent UO 2 processing apparatus where it finally comes into contact with air, the means for receiving, cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO 2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO 2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means

Alloys of uranium and aluminium with low aluminium content

International Nuclear Information System (INIS)

Cabane, G.; Englander, M.; Lehmann, J.

1955-01-01

Uranium, as obtained after spinning in phase γ, presents an heterogeneous structure with large size grains. The anisotropic structure of the metal leads to an important buckling and surface distortion of the fuel slug which is incompatible with its tubular cladding for nuclear fuel uses. Different treatments have been made to obtain an isotropic structure presenting high thermal stability (laminating, hammering and spinning in phase α) without success. Alloys of uranium and aluminium with low aluminium content present important advantage in respect of non allied uranium. The introduction of aluminium in the form of intermetallic compound (UAl 2 ) gives a better resistance to thermal fatigue. Alloys obtained from raw casting present an improved buckling and surface distortion in respect of pure uranium. This improvement is obtained with uranium containing between 0,15 and 0,5 % of aluminium. An even more improvement in thermal stability is obtained by thermal treatments of these alloys. These new characteristics are explained by the fine dispersion of the UAl 2 particles in uranium. The results after treatments obtained from an alloy slug containing 0,4 % of aluminium show no buckling or surface distortion and no elongation. (M.P.)

Uranium

International Nuclear Information System (INIS)

Cuney, M.; Pagel, M.; Leroy, J.

1992-01-01

First, this book presents the physico-chemical properties of Uranium and the consequences which can be deduced from the study of numerous geological process. The authors describe natural distribution of Uranium at different scales and on different supports, and main Uranium minerals. A great place in the book is assigned to description and classification of uranium deposits. The book gives also notions on prospection and exploitation of uranium deposits. Historical aspects of Uranium economical development (Uranium resources, production, supply and demand, operating costs) are given in the last chapter. 7 refs., 17 figs

recovery of enriched uranium from waste solution obtained from fuel fabrication laboratories

International Nuclear Information System (INIS)

Othman, S.H.A.

2003-01-01

reversed-phase partition chromatography is shown to be a convenient and applicable method for the quantitative recovery of uranium (19.7% enriched with 235 U) from highly impure solution . the processing of uranium compounds for atomic energy project especially in FMPP(Egyptian fuel manufacture pilot plant) gives rise to a variety of wastes in which the uranium content is of considerable importance. the recovery of uranium from concentrated mother liquors produced from ADU (ammonium diuranate ) precipitation, as well as those due to ADU washing is studied in this work. column of poly-trifluoro-monochloro-ethilene (Kel-F) supporting tri-n-butyl-phosphate (TBP) retains uranium .impurities are eluted with 6.5 M HCl, and the uranium is eluted with water and the recovery of uranium is better than 94%. A mathematical model was suggested to stimulate the sorption process of uranium ions (or any other ion ) by column of solvent impregnated resin containing organic extractant (the same as the previous column) . An excellent agreement was founded between the experimental results and the mathematical model

On the characteristics of metallotect features and origin of Chanziping uranium deposit

International Nuclear Information System (INIS)

Kang Zili; Liu Haiying

1991-01-01

Chanziping Uranium Deposit is one of the representative uranium deposits which lie in the Lower Cambrian Qingxi Formation in China, Chiefly composed of black shale formation. The mineralization is largely controlled by the U-rich strata and bedding-plane faults. The former is the source of ore and ore-bearing wallrock; the latter controls the distributions of ore bodies, and is the source of force for remobilization, and mineralization of uranium and other metallogenetic elements. The formation of this deposit approximately undergoes the following 4 stages: 1. Preliminary enrichment of sedimentary uranium source layer in the Qingxi Formation; 2. Further uranium enrichment during the deformation and metamorphism of strata; 3. Formation of hydrothermal (thermal water) uranium deposit (main metallogenetic epoch) due to dynamic differentation and thermodynamic metamorphism; 4. Formation of rich multiple ore bodies due to the secondary leaching and enrichment. Then, the deposit, which contains strata-bound features, becomes a polygenetic compound uranium deposit. These characteristics may be used as the rules for searching for uranium deposits of this type

Uranium

International Nuclear Information System (INIS)

Poty, B.; Cuney, M.; Bruneton, P.; Virlogeux, D.; Capus, G.

2010-01-01

With the worldwide revival of nuclear energy comes the question of uranium reserves. For more than 20 years, nuclear energy has been neglected and uranium prospecting has been practically abandoned. Therefore, present day production covers only 70% of needs and stocks are decreasing. Production is to double by 2030 which represents a huge industrial challenge. The FBR-type reactors technology, which allows to consume the whole uranium content of the fuel, is developing in several countries and will ensure the long-term development of nuclear fission. However, the implementation of these reactors (the generation 4) will be progressive during the second half of the 21. century. For this reason an active search for uranium ores will be necessary during the whole 21. century to ensure the fueling of light water reactors which are huge uranium consumers. This dossier covers all the aspects of natural uranium production: mineralogy, geochemistry, types of deposits, world distribution of deposits with a particular attention given to French deposits, the exploitation of which is abandoned today. Finally, exploitation, ore processing and the economical aspects are presented. Contents: 1 - the uranium element and its minerals: from uranium discovery to its industrial utilization, the main uranium minerals (minerals with tetravalent uranium, minerals with hexavalent uranium); 2 - uranium in the Earth's crust and its geochemical properties: distribution (in sedimentary rocks, in magmatic rocks, in metamorphic rocks, in soils and vegetation), geochemistry (uranium solubility and valence in magmas, uranium speciation in aqueous solution, solubility of the main uranium minerals in aqueous solution, uranium mobilization and precipitation); 3 - geology of the main types of uranium deposits: economical criteria for a deposit, structural diversity of deposits, classification, world distribution of deposits, distribution of deposits with time, superficial deposits, uranium

Aplicaciones de redes neuronales en economía.

Directory of Open Access Journals (Sweden)

Pacheco Bonrostro, J.

1997-01-01

Full Text Available La metodología de las Redes Neuronales Artificiales, está siendo usada con profusión, dentro del campo de la Economía, hasta tal punto que existe una publicación bimensual, que trata específicamente estas aplicaciones a los mercados financieros: Neurove$t Journal. En este trabajo, se presentan las principales líneas de investigación existentes, a continuación la que nosotros estamos siguiendo, con algunos resultados iniciales, para finalizar con las líneas a seguir y una selección bibliográfica.

Synthesis of new polyphosphonic acids, uranium extracting agents in a phosphoric medium

International Nuclear Information System (INIS)

Pensec, T.

1981-04-01

Synthesis of organic phosphorus compounds for liquid-liquid extraction of traces of uranium in concentrated phosphoric acid is studied in view of industrial applications. Diphosphonic acids and monoesters and also triphosphonic acids and related compounds are synthetized. Extraction tests show a better efficiency than OPPA [fr

Haré un dibujo aprovechando esta nada. Aplicaciones de dibujo en freeware y opensource

OpenAIRE

Horcajada González, Ricardo

2012-01-01

Breve presentación de la tipología más común de los diferentes programas de sofware libre dedicados al dibujo que pueden encontrarse como freeware en internet. Aplicaciones y distribución de las imágenes.

Implantes personalizados de polimetilmetacrilato (PMMA) para aplicaciones en craneoplastia

OpenAIRE

Arango Ospina, Marcela

2014-01-01

Los implantes a la medida para aplicaciones en craneoplastias tienen el objetivo de restaurar la protección del cerebro que el cráneo proporcionaba y mejorar el aspecto de la superficie después de sufrir un traumatismo o para corregir una malformación. Los principales inconvenientes del procedimiento de craneoplastia incluyen la individualización de la geometría y las propiedades mecánicas del implante para que sea funcional. El objetivo de nuestra investigación fue proponer un...

Solvothermal synthesis of tetravalent uranium with isophthalate or pyromellitate ligands

Energy Technology Data Exchange (ETDEWEB)

Falaise, Clement; Delille, Jason; Volkringer, Christophe; Loiseau, Thierry [Contribution from Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille, USTL-ENSCL, Villeneuve d' Ascq (France)

2015-06-15

Three new coordination polymers bearing tetravalent uranium have been isolated with the O-donor ligands such as isophthalate (1,3-bdc) or pyromellitate (btec). The compounds 1 and 3 have been solvothermally synthesized in N,N-dimethylformamide (DMF). The crystal structure of U(1,3-bdc){sub 2}(DMF) (1) is built up from discrete tricapped trigonal-primastic UO{sub 9} units, for which one carbonyl oxygen atom from DMF is bound to uranium. The connection of the UO{sub 9} units with the isophthalate linkers occurs in a chelating and bidentate fashion and gives rise to the formation of a 3D framework, delimiting narrow channels running along the [101] direction. Upon heating, the DMF molecules are removed, generating the second phase U(1,3-bdc){sub 2} (2) compound, closely related to 1. Indeed, the coordination environment of uranium is reduced to eight with a distorted square-antiprismatic geometry. This transition induces the relative shrinkage of the network (ΔV = 23 %). The structure of the compound U(btec)(DMF){sub 2} (3) also exhibits a 3D framework composed of an isolated bicapped square-antiprismatic UO{sub 10} unit, for which two carbonyl oxygen atoms from DMF are bonded to uranium. Pyromellitate ensures the connection of the UO{sub 10} units through the carboxylate arms in a chelating mode. This results in the formation of a network with diamond-shaped channels, developed along the c axis and encapsulating the DMF molecules. In contrast to 1, no stable phase is observed upon removing the DMF species by heating. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Phosphate Barriers for Immobilization of Uranium Plumes

International Nuclear Information System (INIS)

Burns, Peter C.

2005-01-01

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

Absorption spectra and cyclic voltammograms of uranium species in molten lithium molybdate-sodium molybdate eutectic at 550 C

International Nuclear Information System (INIS)

Nagai, T.; Fukushima, M.; Myochin, M.; Uehara, A.; Fujii, T.; Yamana, H.; Sato, N.

2011-01-01

Absorption spectra of uranium species dissolved in molten lithium molybdate.sodium molybdate eutectic of 0.51Li 2 MoO 4 -0.49Na 2 MoO 4 mixture at 550 C were measured by UV/Vis/NIR spectrophotometry, and their redox reactions were investigated by cyclic voltammetry. We found that the major ions of uranium species dissolved in the melt were uranyl penta-valent. After purging dry oxygen gas into the melt, pentavalent species were oxidized to the uranyl hexa-valent. In the cyclic voltammetry of the melt without uranium species, it was confirmed that the lithium-sodium molybdenum oxide compounds were deposited on the working electrode at the negative potential and the lithium molybdenum oxide compounds were deposited on the counter electrode at positive potential. When UO 2 was dissolved into the melt, the reductive reaction of the uranium species was observed at the reductive potential of the pure melt. This suggests that the uranium species dissolved in the melts could be recovered as mixed uranium-molybdenum oxides by electrolysis. (orig.)

Uranium distribution and fixation in main types of climatic and stational pedogenesis on crystalline rocks

International Nuclear Information System (INIS)

Gueniot, B.

1983-11-01

An experimental and analytical study of uranium behavior in soils and of its distribution was carried out for bioclimatic pedogenesis on crystalline rocks, generally granites. Uranium distribution, and sometimes thorium) is compared to the distribution of tracers of pedogenesis (C, Fe, Al, Si, alkalis, clays). Uranium and thorium behavior is dependent of pedogenesis and can be leached or concentrated. Various fractions of soil alteration complexes and associated uranium can be isolated by chemical and physical fractionation and fixation sites for U are evidenced, efficiency is tested in situ. Adsorption is low onclays, fixation is frequent on oxyhydroxides, organic compounds are active for uranium complexation [fr

The clearance of uranium after deposition of the nitrate and bicarbonate in different regions of the rat lung

International Nuclear Information System (INIS)

Ellender, M.

1987-01-01

This study investigated the tissue distribution and excretion of uranium after its deposition as either the nitrate or bicarbonate in the three regions of the respiratory system of the rat. Results confirm the recommendations of ICRP that uranyl nitrate and bicarbonate should be treated as class D compounds; but imply that some of the parameters used in the ICRP lung model are not applicable to soluble uranium compounds. (author)

Thirty years of uranium ore processing in Spain

International Nuclear Information System (INIS)

Josa, J.M.

1982-01-01

Spanish background in the uranium ore processing includes ores from pegmatitic type deposits, vein deposits, sandstone, enrichments in metamorphic rocks, radioactive coals and non-conventional sources of uranium, such as wet phosphoric acid or copper liquors. Some tests have also done in order to recover uranium from very low grade paleozoic quartzites. We have also been involved in by-products recovery (copper) from uranium ores. The technologies that have been used are: physical concentration, combustion and roasting, conventional alkaline or acid methods, pressure, heap and bacteria leaching. Special attention was paid to recover uranium from the pregnant liquors and to develop suited equipment for it; solvent extraction and continuous ion exchange equipment was carefully studied. We have been involved in commercial size (500-3000 t/d) mills, but we have also developed transportable and reussable modular plants specially designed and suited to recover uranium from small and isolated deposits. In both cases the reduction of the environmental impact was taken in account. Spanish experience also includes nuclear purification aspects in order to get uranium nuclear compounds (ADU, UO 2 , UF 4 and UF 6 ). Wet (nitric-TBP) and dry (Fluid-bed) methods have been used. The best of these 30 years of experience in studies and in industrial practice, together with our new developments towards the future, could become in a good contribution for the medium size countries which are going to develop its own uranium industry. The way for these countries could be easier if they know what is valuable and what must be avoid in the uranium ore processing development. In this aim the whole paper was thought and written. (author)

Selective arsenical purification of substances during an alkaline treatment process of an uranium and/or molybdenum bearing ore by means of a magnesium compound

International Nuclear Information System (INIS)

Maurel, Pierre; Lamerant, J.M.; Pallez, Francois.

1983-01-01

The ores is digested by means of an aqueous liquor of sodium or potassium carbonate and/or bicarbonate, the digestion being carried out under conditions of concentrations, temperatures and pressures bringing about the solubilization of the uranium and/or molybdenum and the arsenic present in the core. A solid phase suspension is lifted from a liquid phase and the phases are separated. The arsenic solubilized during the digestion is extracted as magnesium arsenate by treatment of the medium containing the arsenic by means of a magnesium compound [fr

Study of in vitro toxicity and ex vivo and in vivo efficiency of calixarene galenic forms developed for the treatment of cutaneous contamination due to uranium compounds

International Nuclear Information System (INIS)

Grives, Sophie

2015-01-01

In case of radiological skin contamination by uranium compounds, the only treatments currently available consist in rinsing the contaminated skin area with water and detergent, or with a calcium salt of diethylene triamine pentaacetic acid (Ca-DTPA) solution. However, these procedures are not specific and no efficient treatment for cutaneous contamination due to uranium exists. In the absence of such treatments, uranium diffusion through the skin is fast, inducing an internal exposure after its distribution inside the body through the bloodstream. One part of the bioavailable uranium is up-taken in target organs which are the kidneys and the skeleton, where its toxic effects occur. Therefore a topical formulation consisting of an oil-in-water nano-emulsion incorporating a tricarboxylic calixarene molecule, as a specific chelating agent for uranium, was previously developed. The work achieved in this thesis aimed at evaluating the ex vivo and in vivo decontamination efficiency of this new emergency treatment on intact and superficially wounded skin. For this purpose, skin excoriation model was used. Reproducible models of superficial wounds consisting of micro-cuts and micro-punctures were also developed in order to evaluate the efficiency of the nano-emulsion on physical wounds such as incisions. These studies showed that the calixarene nano-emulsion could be an efficient decontaminating treatment, less aggressive than using the current treatment: soaped water. Its potential cutaneous toxicity was evaluated on in vitro reconstructed human epidermis using three different toxicity tests (MTT, LDH and IL-1-α). These studies demonstrated that the calixarene nano-emulsion did not induce skin toxicity even after 24 h of exposure time. (author)

Obtention of uranium-molybdenum alloy ingots microstructure and phase characterization

Energy Technology Data Exchange (ETDEWEB)

Pedrosa, Tercio A.; Braga, Daniel M.; Paula, Joao Bosco de; Brina, Jose Giovanni M.; Ferraz, Wilmar B., E-mail: tap@cdtn.b, E-mail: bragadm@cdtn.b, E-mail: jbp@cdtn.b, E-mail: jgmb@cdtn.b, E-mail: ferrazw@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2011-07-01

The replacement of high enriched uranium (U-{sup 235} > 85 wt%) by low enriched uranium (U-{sup 235} < 20 wt%) nuclear fuels in research and test reactors is being implemented as an initiative of the Reduced Enrichment for Research and Test Reactors (RERTR) program, conceived in the USA since mid-70s, in order to avoid nuclear weapons proliferation. Such replacement implies in the use of compounds or alloys with higher uranium densities. Several uranium alloys that fill this requirement has been investigated since then. Among these alloys, U-Mo presents great application potential due to its physical properties and good behavior during irradiation, which makes it an important option as a nuclear fuel material for the Brazilian Multipurpose Reactor - RMB. The development of the plate-type nuclear fuel based on U-Mo alloys is being performed at the Nuclear Technology Development Centre (CDTN) and also at the Institute of Energetic and Nuclear Research - IPEN. U-{sup 10}Mo ingots were melted in an induction furnace with protective argon atmosphere. The microstructure of the ingots were characterized through optical and scanning electronic microscopy in the as cast and heat treated conditions. Energy Dispersive Spectrometry and X-Ray Diffraction were used as characterization techniques for elemental analysis and phases determination. It was confirmed the presence of metastable gamma-phase in the as cast condition, surrounded by hypereutectoid alpha-phase (uranium-rich phase), as well as a pearlite-like constituent, composed by alternated lamellas of U{sub 2}Mo compound and alpha-phase, in the heat treated condition. (author)

Spectrographic determination of microconstituents in uranium tetrafluoride

International Nuclear Information System (INIS)

Paula Reino, L.C. de; Lordello, A.R.

1982-11-01

A espectrographic method for the direct determination of impurities in uranium tetrafluoride (UF 4 ) was developed. The major impurities introduced during the preparation of UF 4 (Fe, Ni, Cr) and other impurities introduced in the prior stages of this preparation were determined. Spectrochemical carriers were used to suppress the uranium distillation during excitation, because fluoride compound is more volatile the refractory matrix (U 3 O 8 ). Better results were obtained using as carrier a mixture of 20% MgO and 10% MgO and 10% NaCl, concerning to the UF 4 matrix. The sensibilities for some of those impurities are in the ppm level. (Author) [pt

Las aplicaciones interactivas multimedia en España: ¿hacia dónde evoluciona el mercado?

Directory of Open Access Journals (Sweden)

Lic. Nati Ramajo Hernández

1998-01-01

Full Text Available El despegue del sector multimedia en nuestro país (entendiendo como tal las aplicaciones interactivas multimedia ha sido espectacular en los últimos tiempos. El número de títulos publicados en CD-ROM, al igual que el número de productores, ha aumentado considerablemente. Pero, ¿cómo es esa nueva industria?, ¿qué productos ofrece?, ¿hacia dónde evoluciona el mercado? El presente trabajo pretende hacer un repaso a la breve historia de las aplicaciones interactivas multimedia en España hasta llegar al momento actual, analizando por el camino la tipología de los productos y concluyendo con los nuevos formatos que están cambiando el mercado.

Arquitecturas multiprocesador en HPC: software, métricas y aplicaciones

OpenAIRE

De Giusti, Armando Eduardo; Tinetti, Fernando Gustavo; Naiouf, Marcelo; Chichizola, Franco; De Giusti, Laura Cristina; Villagarcía Wanza, Horacio A.; Montezanti, Diego Miguel; Encinas, Diego; Pousa, Adrián; Rodriguez, Ismael Pablo; Eguren, Sebastián; Iglesias, Luciano; Paniego, Juan Manuel; Pi Puig, Martín; Dell'Oso, Matías

2016-01-01

Caracterizar las arquitecturas multiprocesador distribuidas enfocadas especialmente a cluster y cloud computing, con énfasis en las que utilizan procesadores de múltiples núcleos (multicores, GPUs y Xeon Phi), con el objetivo de modelizarlas, estudiar su escalabilidad, analizar y predecir performance de aplicaciones paralelas, estudiar el consumo energético y su impacto en la perfomance así como desarrollar esquemas para detección y tolerancia a fallas en las mismas. Profundizar el estudio...

Machining of uranium and uranium alloys

International Nuclear Information System (INIS)

Morris, T.O.

1981-01-01

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

Uranium recovery from slags of metallic uranium

International Nuclear Information System (INIS)

Fornarolo, F.; Frajndlich, E.U.C.; Durazzo, M.

2006-01-01

The Center of the Nuclear Fuel of the Institute of Nuclear Energy Research - IPEN finished the program of attainment of fuel development for research reactors the base of Uranium Scilicet (U 3 Si 2 ) from Hexafluoride of Uranium (UF 6 ) with enrichment 20% in weight of 235 U. In the process of attainment of the league of U 3 Si 2 we have as Uranium intermediate product the metallic one whose attainment generates a slag contend Uranium. The present work shows the results gotten in the process of recovery of Uranium in slags of calcined slags of Uranium metallic. Uranium the metallic one is unstable, pyrophoricity and extremely reactive, whereas the U 3 O 8 is a steady oxide of low chemical reactivity, what it justifies the process of calcination of slags of Uranium metallic. The calcination of the Uranium slag of the metallic one in oxygen presence reduces Uranium metallic the U 3 O 8 . Experiments had been developed varying it of acid for Uranium control and excess, nitric molar concentration gram with regard to the stoichiometric leaching reaction of temperature of the leaching process. The 96,0% income proves the viability of the recovery process of slags of Uranium metallic, adopting it previous calcination of these slags in nitric way with low acid concentration and low temperature of leaching. (author)

Aplicaciones Nutraceúticas y cosmeceúticas de las algas

OpenAIRE

López-Figueroa, Félix

2017-01-01

El uso de la biomasa algal en diversas aplicaciones biotecnológicas ha experimentado un gran desarrollo en los últimos años. El crecimiento de las publicaciones científicas con contenidos como “extractos de algas”, “compuestos bioactivos de algas”, “biorremediación” o ”cosmética con algas” ha sido exponencial. Dentro de la Biotecnología azul se ha generado un mercado muy dinámico en el que la acuicultura, cosméticos, nutracéuticos e ingredientes funcionales tienen un gran peso. Los campos ...

Mindfulness: Conceptos generales, psicoterapia y aplicaciones clínicas.

OpenAIRE

Vásquez-Dextre, Edgar R.

2016-01-01

El objetivo de este artículo es presentar una revisión sobre el concepto de Mindfulness, su uso en la psicoterapia y sus aplicaciones clínicas. Mindfulness es una técnica de meditación que consiste en observar la realidad en el momento presente, sin intenciones de juzgar y conplena apertura y aceptación. Existen terapias que usan Mindfulness dentro de su estructura y sus programas, tales como como la Terapia Dialéctico-Conductual y la Reducción del Estrés basada en Mindfulness. Mindfulness ha...

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)

Synthesis and reactivity of uranium (III) cyclopentadienyl complexes

International Nuclear Information System (INIS)

Foyentin, M.

1987-01-01

New uranium organometallic complexes are synthetized from the addition compound Cp U (THF). Reactions with lithium compounds, chlorides, alkynes and borohydrides. Oxidizing addition reactions are evidenced with alkyl halogenides. With a strong reducing agent, the complex Cp-UCH-Li allows the fixation and the reduction of nitrogen into ammonia. Lability of ligands bound to U (III) is evidenced, giving very reactive species and hence catalytic properties for these compounds. Catalytic hydrogenation of olefins is studied. Substitution reactions of alkyl groups of these complexes with olefins in presence or not of hydrogen or with alkyllithium are original [fr

Cerium compounds in the fashion of the light actinides

International Nuclear Information System (INIS)

Koelling, D.D.

1985-01-01

Researchers familiar with the light actinides easily recognize in cerium compounds a microcosm of the rich variety of properties seen in the light actinides. The parallelism seen between comparable cerium and actinide compounds strongly suggests that the same physical models are applicable. The most significant is the relative size of the f-orbital. Localization is generally tighter in Ce compounds than uranium compounds, making Ce roughly analogous to Np through Am. A way to see the actinide parallelism is to compare Hill plots. Compounds in the different regions of the plots (representing different physics) are isostructural compounds with the same companion (B) elements. The most common materials expected to exhibit direct f-f interaction are the cubic Laves compounds. Accordingly, we have determined the band structures of CeRu 2 , CeRh 2 , CeIr 2 , and CeNi 2 . Surprisingly, it was found that an f-d interaction overshadows any direct f-f interaction in these systems. Compounds illustrative of the interaction of f-orbitals with ''ligand'' orbitals are the Cu 3 Au structured materials. Materials calculated in this class are CeRh 3 , CePd 3 , and CeSn 3 - the materials of much interest as ''mixed valent''. Although the focus is on the Ce compounds, calculations performed on uranium isomorphs are used to highlight the interesting physics. (orig.)

Determination of UO2F2, UO2 and UF4 in tetrafluoride of uranium samples

International Nuclear Information System (INIS)

Contreras Guzman, Ariel; Arlegui Hormazabal, Oscar

2003-01-01

The combustible elements for investigation reactors that at the present are manufacturing by the Chilean Nuclear Energy Commission (CCHEN) they are based on aluminum and silicide uranium powdered which is obtained from metallic uranium. At the present the Conversion Units, is developing the technology of transformation UF 6 in metallic Uranium, reason for which is necessary that the Chemical Analysis Laboratory have a methodology that allows to quantify the presence of UO 2 F 2 , UO 2 and UF 4 in the samples obtained in this transformation process. For this reason we are implements the methodology of sequential analysis that had been developed previously, for the Institute of Energy and Nuclear Investigations, IPEN Brasil, and to adapt it to the present conditions in the Laboratory of Chemical Analysis of the CCHEN. This method is based on the different solubilities that present those sample in front of solvents as ethanol and solutions of ammonium oxalate, what allows the separation of these compounds for a later analysis by means of the method of Davies and Gray. This method is based on the reduction of the uranium (VI) to uranium (IV) with ferrous ion amid phosphoric acid, quantifying the present uranium in the samples by means of titration with potassium dicromate. With the purpose of checking the efficiency of the method, the sum of all values of uranium coming from each compound and compares it with the total uranium of the sample (author)

Distribution of uranium in marine sediments

International Nuclear Information System (INIS)

Ordonez R, E.; Ramirez T, J.J.; Lopez M, J.; Aspiazu, J.; Ruiz F, A.C.; Valero C, N.

2008-01-01

The marine sediments obtained by means of a sampling nucleus in the Gulf of Tehuantepec, Mexico, they have been object of crystallographic and morphological characterization. The PIXE analysis of some samples in study is shown. The normal methodology to carry out the alpha spectroscopy indicates that the sample should be dissolved, but due to the nature of the marine sediments, it thinks about the necessity to make a fractional separation of the sample components. In each stratum of the profile it separates the organic part and the mineral to recover the uranium. It was observed that in the organic phase, the uranium is in two oxidation states (IV and Vl), being necessary the radiochemical separation with a liquid/liquid column chromatographic that uses the di-2-ethyl hexyl phosphoric acid as stationary phase. The uranium compounds extracts are electrodeposited in fine layers on stainless steel disks to carry out the analysis by alpha spectroscopy. The spectroscopic analysis of the uranium indicates us that for each stratum one has a difference marked in the quotient of activities of 234 U/ 238 U that depends on the nature of the studied fraction. These results give us a clear idea about how it is presented the effect of the uranium migration and other radioelements in the biosphere, with what we can determine which are the conditions in that these have their maximum mobility and to know their diffusion patterns in the different media studied. (Author)

The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains

Energy Technology Data Exchange (ETDEWEB)

Pan, Xiaohong; Chen, Zhi [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China); Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Fanbing [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China); Cheng, Yangjian [Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Lin, Zhang, E-mail: zlin@fjirsm.ac.cn [Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Guan, Xiong, E-mail: guanxfafu@126.com [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China)

2015-10-30

Highlights: • Indigenous B. thuringiensis exhibited highly accumulation ability to U(VI) in the absence of additional nutrients. • The amorphous uranium compound would transformed into crystalline nano-uramphite by B. thuringiensis. • The chemical nature of formed U-species were monitored. • The cell-free extracts of B. thuringiensis had better uranium-immobilization ability than its cell debris. • Provided the understanding of the uranium transformation mechanism. - Abstract: The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains was investigated in the present work. Our data showed that the bacteria isolated from uranium mine possessed highly accumulation ability to U(VI), and the maximum accumulation capacity was around 400 mg U/g biomass (dry weight). X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyzes indicated that the U(VI) was adsorbed on the bacterial surface firstly through coordinating with phosphate, −CH{sub 2} and amide groups, and then needle-like amorphous uranium compounds were formed. With the extension of time, the extracellular crystalline substances were disappeared, but some particles were appeared in the intracellular region, and these particles were characterized as tetragonal-uramphite. Moreover, the disrupted experiment indicated that the cell-free extracts had better uranium-immobilization ability than cell debris. Our findings provided the understanding of the uranium transformation process from amorphous uranium to crystalline uramphite, which would be useful in the regulation of uranium immobilization process.

The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains

International Nuclear Information System (INIS)

Pan, Xiaohong; Chen, Zhi; Chen, Fanbing; Cheng, Yangjian; Lin, Zhang; Guan, Xiong

2015-01-01

Highlights: • Indigenous B. thuringiensis exhibited highly accumulation ability to U(VI) in the absence of additional nutrients. • The amorphous uranium compound would transformed into crystalline nano-uramphite by B. thuringiensis. • The chemical nature of formed U-species were monitored. • The cell-free extracts of B. thuringiensis had better uranium-immobilization ability than its cell debris. • Provided the understanding of the uranium transformation mechanism. - Abstract: The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains was investigated in the present work. Our data showed that the bacteria isolated from uranium mine possessed highly accumulation ability to U(VI), and the maximum accumulation capacity was around 400 mg U/g biomass (dry weight). X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyzes indicated that the U(VI) was adsorbed on the bacterial surface firstly through coordinating with phosphate, −CH 2 and amide groups, and then needle-like amorphous uranium compounds were formed. With the extension of time, the extracellular crystalline substances were disappeared, but some particles were appeared in the intracellular region, and these particles were characterized as tetragonal-uramphite. Moreover, the disrupted experiment indicated that the cell-free extracts had better uranium-immobilization ability than cell debris. Our findings provided the understanding of the uranium transformation process from amorphous uranium to crystalline uramphite, which would be useful in the regulation of uranium immobilization process

Reuse of ammonium fluoride generated in the uranium hexafluoride conversion

International Nuclear Information System (INIS)

Silva Neto, J.B.; Carvalho, E.F. Urano de; Durazzo, M.; Riella, H.G

2010-01-01

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 3 Si 2 ) dispersed in aluminum. For producing the fuel, the processes for uranium hexafluoride (UF 6 ) conversion consist in obtaining U 3 Si 2 and / or U 3 O 8 through the preparation of intermediate compounds, among them ammonium uranyl carbonate - AUC, ammonium diuranate - DUA and uranium tetrafluoride - UF 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 4 + ), fluoride (F - ), carbonate (CO 3 -- ) and low concentrations of uranium. The procedure is basically the recovery of NH 4 F and uranium, as UF 4 , through the crystallization of ammonium bifluoride (NH 4 HF 2 ) and, in a later step, the addition of UO 2 , occurring fluoridation and decomposition. The UF 4 obtained is further diluted in the UF 4 produced routinely at IPEN / CNEN-SP by a wet route process. (author)

Neutron activation analysis of high pure uranium using preconcentration

International Nuclear Information System (INIS)

Sadikov, I.I.; Rakhimov, A.V.; Salimov, M.I.; Zinov'ev, V.G.

2006-01-01

Full text: Uranium and its compounds are used as nuclear fuel, and requirements for purity of initial uranium are very high. Therefore highly sensitive and multielemental analysis of uranium is required. One of such methods is neutron activation analysis (NAA). During irradiation of uranium by nuclear reactor neutrons the induced radioactivity of a sample is formed by uranium radionuclide 239 U (T 1/2 = 23,4 min.) and its daughter radionuclide 239 Np (T 1/2 = 2,39 d). Short-lived 239 U almost completely decays in 24 hours after irradiation and the radioactivity of the sample is mainly due to 239 Np and is more than 10 9 Bq for 0.1 g of uranium sample (F = 1*10 14 cm -2 s -1 , t irr . = 5 h). That is why nondestructive determination of the impurities is impossible and they should be separated from 239 Np. When irradiated uranium yields fission products - radionuclides of some elements with mass numbers 91-104 and 131-144. The main problem in NAA of uranium is to take into account correctly the influence of fission products on the analysis results. We have developed a radiochemical separation procedure for RNAA of uranium [1]. Comparing the results of analysis carried out by radiochemical NAA and instrumental NAA with preconcentration of trace elements can be used for evaluating the interference of fission products on uranium analysis results. Preconcentration of trace elements have been carried out by extraction chromatography in 'TBP - 6M HNO 3 ' system [1]. Experiments have shown that if 0.1 g uranium sample is taken for analysis (F = 1*10 14 cm -2 s -1 , t irr . =5 h) the apparent concentration of Y, Zr, Mo, Cs, La, Ce, Pr, Nd exceeds the true concentration by 2500-3000 times and so determination of these elements is not possible by radiochemical NAA. (author)

Paralelización de aplicaciones econométricas que requieren estimación de los modelos de elección discreta

OpenAIRE

Trigila, Mariano; Di Pasquale, Ricardo

2016-01-01

En las últimas dos décadas, el uso eficiente del hardware para aplicaciones científicas fue creciendo en dificultad. Además, muchas de estas aplicaciones requieren mejorar el rendimiento del procesamiento y tratar datos masivos. Estos son sistemas complejos de implementar y en especial para aquellos que no son especialista en computación. Es necesario desarrollar e implementar abstracciones de programación de alto nivel que permitan modelos de programación simples de usar. Las aplica...

The chemical industry of uranium in France

International Nuclear Information System (INIS)

Goldschmidt, B.

1955-01-01

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 process until the obtention of uranium rich concentrate are described. The purification steps of uranium compounds to nuclear purity material are described as well as the steps to elaborate metal of which the purity grade will be specify. Finally, the economic aspects of uranium production difficulty will be considered in relation with technical progresses which we can expect to achieve in the future. (M.P.)

Possible uranium sources of Streltsovsky uranium ore field

International Nuclear Information System (INIS)

Zhang Lisheng

2005-01-01

The uranium deposit of the Late Jurassic Streltsovaky caldera in Transbaikalia of Russia is the largest uranium field associated with volcanics in the world, its uranium reserves are 280 000 t U, and it is the largest uranium resources in Russia. About one third of the caldera stratigraphic pile consists of strongly-altered rhyolites. Uranium resources of the Streltsovsky caldera are much larger than any other volcanic-related uranium districts in the world. Besides, the efficiency of hydrothermal alteration, uranium resources appear to result from the juxtaposition of two major uranium sources; highly fractionated peralkaline rhyolites of Jurassic age in the caldera, and U-rich subalkaline granites of Variscan age in the basement in which the major uranium-bearing accessory minerals were metamict at the time of the hydrothermal ore formation. (authors)

Distribution of uranium in dental porcelains by means of the fission track method

International Nuclear Information System (INIS)

Shimizu, Masami; Noguchi, Kunikazu; Moriwaki, Kazunari; Sairenji, Eiko

1980-01-01

Porcelain teeth, some of which contain uranium compounds for aesthetic purpose, have been widely used in dental clinics. Hazardous effects due to uranium radiation have been suggested by recent publications. In the previous study, the authors reported the uranium content of porcelain teeth and radiation dose by it. In this study, using the fission track method, the authors examined spatial distribution of uranium in dental porcelain teeth (4 brands) which were marketed in Japan. From each sample of porcelain tooth, a 1-mm-thick specimen was sliced, and uranium content was measured at every 0.19 mm from labial side to lingual side for making a uranium distribution chart. Higher uranium concentration was found in Trubyte Bioblend porcelain teeth (USA) and they showed almost uniform distribution of uranium, while those of the Japanese three brands indicated, in most case, comparatively lower concentration and found to be non-uniform distributions. Range of uranium concentration in these brands were N.D. -- 5.2 ppm (Shofu-Ace), N.D. -- 342 ppm (Shofu-Real), N.D. -- 47 ppm (G.C. Livdent) and N.D. -- 235 ppm (Trubyte Bioblend), respectively. (author)

Process for continuous production of metallic uranium and uranium alloys

Science.gov (United States)

Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

1995-01-01

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

Process for continuous production of metallic uranium and uranium alloys

Science.gov (United States)

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

1995-06-06

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

Organic matter in North Bohemian Tertiavy and Cretaceous sediments with uranium mineralization

International Nuclear Information System (INIS)

Simanek, V.

1979-01-01

Significant variability was found in the qualitative and the quantitative compositions of dispersed organic matter in Tertiary rocks with uranium ore content between hundredths and units of percentage of the rocks. In Cretaceous rocks with similar proportion of uranium in w.% the variability is much smaller. In rocks with higher organic carbon and uranium levels the organic matter is in a more advanced stage of carbonification metamorphosis than in rocks with lower levels of the components. A statistical correlation test showed free positive correlation between the levels of uranium and organic carbon and the levels of uranium and strongly carbonified organic components and negative correlation between uranium level and humic substances on one hand and the uranium level and bitumens on the other. In Cretaceous sediments, the individual organic compounds were analytically determined in addition to the total level of organic carbon, the strongly carbonified organic components, humic substances and bitumens. Higher fatty acids in ppm concentrations were also found. Their distribution corresponds to the usual distribution in sediments. Rocks with lower contents of organic matter and uranium usually contain phenol aldehydes bound to glycosides while those with higher contents of uranium and organic carbon contain higher amounts of free phenol aldehydes. The composition of amino acids indicates genetic links to the microbial activity. (author)

Preparation and melting of uranium from U3O8

International Nuclear Information System (INIS)

Hur, Jin-Mok; Choi, In-Kyu; Cho, Soo-Haeng; Jeong, Sang-Mun; Seo, Chung-Seok

2008-01-01

In this paper, we report on the preparation and melting of uranium in association with a spent nuclear fuel conditioning process. U 3 O 8 powder was electrochemically reduced in a mixture of molten LiCl-Li 2 O (∼3 wt.% of Li 2 O in LiCl) at 650 deg. C resulting in the formation of uranium and Li 2 O with a yield of >99%. When the powder of uranium with a residual LiCl-Li 2 O salt was heated in order to melt the metal, the uranium oxidation to UO 2 due to the reaction with Li 2 O was observed. We were able to synthesize FeU 6 by using a Fe based cathode during the U 3 O 8 reduction procedure. FeU 6 could be melted to below the temperatures where the oxidation of uranium by Li 2 O occurred. The idea of compound formation and melting is applicable to the melting and casting of a spent nuclear fuel which contains oxidative residual salts due to its conditioning in a molten salt

Fluorinated compounds in the uranium conversion process: risk analysis and proposition of pictograms

International Nuclear Information System (INIS)

Jeronimo, Adroaldo Clovis; Oliveira, Wagner dos Santos

2012-01-01

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)

Propiedades y aplicaciones de los materiales aislantes a base de vidrio espumado

Directory of Open Access Journals (Sweden)

Sánchez Castro, Carlos

1958-02-01

Full Text Available Not availableEn un artículo precedente, aparecido en el núm. 82 de U. A. M. C., se definieron y estudiaron brevemente los materiales aislantes a base de vidrio espumado -Foamglas-, dedicándose una atención más amplia a los procedimientos y ensayos de laboratorio, realizados para obtener la máxima espumación del producto. Entonces sólo se mencionaron algunas de sus características y propiedades más importantes; también se indicaron, sin entrar en detalles, algunas de sus aplicaciones. Seguidamente, y como complemento de lo anteriormente dicho, se van a enumerar: las características de este material, pesos específicos, coeficientes de aislamiento, resistencias, etc.; los productos que con él se fabrican, bloques, planchas, coquillas, etc.; y las distintas aplicaciones que tiene en la construcción y en otras industrias, a las cuales beneficia con su colaboración, resolviendo problemas de aislamiento, aligeramiento de peso, etc. En distintas fotografías se presentan algunos ejemplos de aislamiento, de edificios, fijación de piezas y enlucido o revestimiento de los paramentos realizados con este producto.

Potenciales aplicaciones de Moringa oleifera. Una revisión crítica

Directory of Open Access Journals (Sweden)

C Martín

Full Text Available Moringa oleifera es un árbol originario de la India al que se le atribuyen múltiples beneficios para el bienestar humano. Es de crecimiento rápido, de relativamente poca exigencia hacia el suelo y se cultiva en toda la franja intertropical. Uno de los principales usos de sus hojas y de la torta de prensado de su semilla es en la formulación de raciones para la alimentación animal. Sin embargo, prácticamente todas las partes del árbol tienen diversas aplicaciones, sobre lo cual existen testimonios que se remontan a la Antigüedad. En este trabajo se hace una revisión de la literatura disponible sobre la utilización de esta planta. Se presentan distintos campos de aplicación de M. oleifera a la luz del creciente interés científico que ha generado en los últimos lustros. El objetivo es presentar las evidencias aportadas por la literatura científica que confirman y explican las propiedades y aplicaciones de la moringa, las cuales se distancian de versiones sin confirmar aportadas por la literatura popular y la publicidad.

Structural and magnetic properties of some pseudo-binary and ternary compounds at high curie temperature prepared in the systems: -) rare earth (Nd, Sm) iron hydrogen, -) gadolinium iron aluminium, and -) uranium iron or cobalt silicon or germanium; Proprietes structurales et magnetiques de quelques composes pseudobinaires et ternaires ferromagnetiques a temperature de curie elevee prepares dans les systemes: -) terres rares Nd Sm fer hydrogene, -) gadolinium fer aluminium, and -) uranium fer ou cobalt silicium ou germanium

Energy Technology Data Exchange (ETDEWEB)

Berlureau, T

1991-07-15

This work highlights the importance of crystal and chemical studies for understanding the magnetic properties of systems as complex as inter-metallic compounds involving rare-earth elements, uranium, silicon or germanium. With a view of finding new compounds with high Curie temperature and strong magneto-crystal anisotropy, it appears that uranium compounds such as UFe{sub 10}Si{sub 2}, UCo{sub 10}Si{sub 2}, U(Fe{sub 10-x}Co{sub x})Si{sub 2} and U{sub 2}M{sub 17-y}X{sub y} where M is Fe or Co and Y is Si or Ge, are interesting because of the 5f orbital that can form bands through direct overlapping and can link itself very strongly with orbitals of nearby atoms.

Study on the uranium-cerium extraction and his application to the treatment of irradiated uranium

International Nuclear Information System (INIS)

Lobao, Afonso dos Santos Tome

1979-01-01

It was made a study on the behavior of uranium and cerium(IV) extraction, using the latter element as a plutonium simulator in a flowsheet of the treatment of irradiated uranium. Cerium(IV) was used under the same conditions as a plutonium in the Purex process because the admitted similar properties. An experimental work was initiated to determine the equilibrium curves of uranium, under the following conditions: concentration of 1 to 20 g U/1 and acidity varying from 1 to 5M in HNO 3 . Other parameters studied were the volumetric ratio of the phases and the influence of the concentration of TBP (tri-n-butyl phosphate). To guarantee the cerium(IV) extraction, the diluent (varsol) was previously treated with 10% potassium dichromate in perchloric acid, potassium permanganate in 1M sulphuric acid and concentrated sulphuric acid at 70 deg to eliminate reducing compounds. The results obtained for cerium extraction, allowed a better understanding of its behavior in solution. The results permitted to conclude that the decontamination for cerium are very high in the first Purex extraction cycle. The easy as cerium(IV) is reduced to the trivalent state contributes a great deal to its decontamination. (author)

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.

Experimental study on uranium alloys for hydrogen storage

International Nuclear Information System (INIS)

Deaconu, M.; Meleg, T.; Dinu, A.; Mihalache, M.; Ciuca, I.; Abrudeanu, M.

2013-01-01

The heaviest isotope of hydrogen is one of critically important elements in the field of fusion reactor technology. Conventionally, uranium metal is used for the storage of heavier isotopes of hydrogen (D and T). Under appropriate conditions, uranium absorbs hydrogen to form a stable UH 3 compound when exposed to molecular hydrogen at the temperature range of 300-500 O C at varied operating pressure below one atmosphere. However, hydriding-dehydriding on pure uranium disintegrates the specimen into fine powder. The powder is highly pyrophoric and has low heat conductivity, which makes it difficult to control the temperature, and has a high possibility of contamination Due to the powdering effect as hydrogen in uranium, alloying uranium with other metal looks promising for the use of hydrogen storage materials. This paper has the aim to study the hydriding properties of uranium alloys, including U-Ti U-Mo and U-Ni. The uranium alloys specimens were prepared by melting the constituent elements by means of simultaneous measurements of thermo-gravimetric and differential thermal analyses (TGA-DTA) and studied in as cast condition as hydrogen storage materials. Then samples were thermally treated under constant flow of hydrogen, at various temperatures between 573-973 0 K. The structural and absorption properties of the products obtained were examined by thermo-gravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). They slowly reacted with hydrogen to form the ternary hydride and the hydrogenated samples mainly consisted of the pursued ternary hydride bat contained also U or UO 2 and some transient phase. (authors)

Oxidation state analyses of uranium with emphasis on chemical speciation in geological media

International Nuclear Information System (INIS)

Ervanne, H.

2004-01-01

This thesis focuses on chemical methods suitable for the determination of uranium redox species in geological materials. Nd-coprecipitation method was studied for the determination of uranium oxidation states in ground waters. This method is ideally suited for the separation of uranium oxidation states in the field, which means that problems associated with the instability of U(IV) during transport are avoided. An alternative method, such as ion exchange, is recommended for the analysis of high saline and calcium- and iron-rich ground waters. U(IV)/Utot was 2.8-7.2% in ground waters in oxidizing conditions and 60-93% in anoxic conditions. From thermodynamic model calculations applied to results from anoxic ground waters it was concluded that uranium can act as redox buffer in granitic ground waters. An ion exchange method was developed for the analysis of uranium oxidation states in different solid materials of geological origin. These included uranium minerals, uraniumbearing minerals, fracture coatings and bulk rock. U(IV)/Utot was 50-70% in uraninites, 5.8-8.7% in secondary uranium minerals, 15-49% in different fracture coatings and 64- 77% in samples from deep bedrock. In the uranium-bearing minerals, U(IV)/Utot was 33-43% (allanites), 5.9% (fergusonite) and 93% (monazite). Although the ion exchange method gave reliable results, there is a risk for the conversion of uranium oxidation states during analysis of heterogeneous samples due to the redox reactions that take place in the presence of some iron compounds. This risk was investigated in a study of several common iron-bearing minerals. The risk for conversion of uranium oxidation states can be screened by sample selection and minimized with use of a redox buffer compound such as polyacrylic acid (PAA). In studies of several carboxylic acids, PAA was found to be the most suitable for extending the application of the method. The stability of uranium oxidation states during analysis and the selectivity

Magnetic anisotropy in intermetallic compounds containing both uranium and 3d-metal

Czech Academy of Sciences Publication Activity Database

Andreev, Alexander V.; Tereshina, Evgeniya; Gorbunov, Denis; Šantavá, Eva; Šebek, Josef; Žáček, Martin; Homma, Y.; Shiokawa, Y.; Satoh, I.; Yamamura, Y.; Komatsubara, T.; Watanabe, K.; Koyama, K.

2013-01-01

Roč. 114, č. 9 (2013), s. 727-733 ISSN 0031-918X R&D Projects: GA ČR GAP204/12/0150 Institutional support: RVO:68378271 Keywords : uranium intermetallics * magnetic anisotropy * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.605, year: 2013

EL COMPROMISO EN LA TEORÍA DE LA VALORACIÓN: CONCEPTOS Y APLICACIONES PEDAGÓGICAS

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Jesús David Guerra Lyons

2017-01-01

Full Text Available El presente artículo revisa el concepto de compromiso desde la Teoría de la Valoración propuesta por Martin y White y de algunas de sus aplicaciones pedagógicas. Desde la perspectiva bajtiniana de dialogismo, Martin y White definen el compromiso como el conjunto de recursos mediante los cuales los usuarios del lenguaje entran en diálogo con las múltiples voces que inevitablemente permean sus textos, aceptándolas, rebatiéndolas, retomándolas o distanciándose de ellas. El compromiso se divide en dos tipos: monoglosia y heteroglosia. Este último se desagrega en varias subcategorías, que son definidas e ilustradas con ejemplos tomados del corpus del español de Davies. Consideramos algunas aplicaciones pedagógicas del concepto de compromiso mediante la revisión de estudios desarrollados principalmente en el contexto latinoamericano.

Spectrofluorimetric determination of microquantities of aluminium in uranium

International Nuclear Information System (INIS)

Gomiero, L.A.; Nascimento, M.R.L. do; Abraao, A.

1976-01-01

A rapid and sensitive method for the separation and spectrofluorimetric determination of microamounts of aluminium in uranium compounds is described. In sodium carbonate solution at pH 9.5-10.0, the uranyl ion forms a very stable anionic complex with the carbonate ion. In these conditions, uranium is not extracted by a chloroform oxine solution, while alumium is isolated as the tris(oxinate)aluminium(III) form. The interferences are previously extracted with chloroform as diethylditiocarbomates in the same tris(oxinate)aluminum(III) pH extraction. The sensitivity is 0,005 μ Al/ml of organic phase and the relative standard deviation is 10% [pt

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

Interest of uranium complexes for the mechanism study of the McMurry reaction; Interet des complexes de l`uranium pour l`etude du mecanisme de la reaction de McMurry

Energy Technology Data Exchange (ETDEWEB)

Maury, O

1997-07-04

The reducing coupling reactions of ketones in diols and olefins are generally carried out with titanium or samarium compounds. In this work uranium complexes have been used. They have allowed to study the chemical reaction mechanism. This thesis is divided into three parts: 1) the reduction mechanism of uranium tetrachloride by cyclic voltametry has been studied at first. It has been shown that this reduction is followed by a transfer reaction of chlorides between the reduced specie of the higher electronic density and UCl . 2) In the second part is described: the synthesis, the crystal structure, the reactivity of the chemical agents, the stereochemistry of diols and alkenes formation and the pinacolisation reaction catalysis. 3) In the last part, the limits of the McMurry reaction are given by the study of the aromatic ketones pinacolisation reaction by-products. The obtained results show that the complexes of the metals which present a high reducing and oxo-philic (Ti, Sm, U..) character react in a similar way with the carbonyl compounds. If the uranium compounds are less used than those of the titanium in the field of the organic synthesis applications, they are precious auxiliaries and excellent models for reactions mechanisms study and for the synthesis methods optimization. (O.M.). 284 refs.

Titration of uranium trace amounts in waters environment

International Nuclear Information System (INIS)

Larabi-Gruet, N.; Ithurbide, A.; Poulesquen, A.; Beaucaire, C.; Peulon, S.; Chausse, A.

2007-01-01

In the framework of studies concerning the uranium migration in soils and rocks, it seems necessary to quantify the uranium(VI) dissolved in solution. In the environmental conditions, the uranium(VI) is present at trace amounts. The most adapted method to this study and easy to carry out is the Adsorptive Stripping Voltammetry. By addition of a compound (ligand) with a reducing and strong complexing power, the uranium(VI) present in solution is reduced into a U(VI)-ligand complex. This specie is then oxidized and adsorbed on the mercury droplet where an electrolytic pre-concentration of the element to determine the quantity of is carried out. At last, a cathodic re-dissolution of the specie adsorbed in the U(IV)-ligand complex is carried out. The chosen analytical method is the differential impulsional voltammetry. With this method, it is possible to quantify low electro-active species quantities (sensitivity ∼25 ppt (10 -10 mol.L -1 ) for the uranium). This titration method in solution has been optimized, at first, in a non complexing medium. Then, the uranium in solution has been titrated in media whose composition has been progressively complexed (additions of CO 3 2- , SO 4 2- , Cl - ..) for being at last representative of the environmental interstitial waters. At last, this study has been carried out too by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) in order to compare the analysis sensitivity of these two detection methods. (O.M.)

Uranium in Malwa region of Punjab, India

International Nuclear Information System (INIS)

Kochhar, Naresh; Dadwal, Veena; Balaram, V.

2012-01-01

It is well known in Punjab that the Malwa region shows a very high incidence of cancer, stunted growth and other neurological disorders. The high values of uranium have been attributed to Kota nuclear power plant; Khushab heavy water plant in Pakistan; and uranium - carrying winds from Afghanistan, without any scientific basis. Though Malwa is a part of Punjab, geologically it is more akin to Haryana and Rajasthan. Uranium is a naturally occurring radioactive element which is present in trace in rocks, minerals plants and natural waters. It occurs along with thorium and potassium in granitic rocks. It has the property to get dissolved in water in hexavalent form at a normal pH of 5 to 7. It gets precipitated in the reducing environment in tetravalent form and form complexes such as hydroxides, phosphate, sulfate, carbonate etc. Uranium compounds are soluble in water, very mobile and travel kilometers. When the bed rocks containing uranium and thorium and other elements are exposed to sun, rain, wind, they get weathered and breakdown to form soil. Uranium gets dispersed in matrix, soil and finally gets re-deposited in areas/pockets where reducing conditions are present. Hence we get higher concentration of uranium in pockets. There are no rocks exposed on the surface in the SW Punjab. However the rocks of Aravalli-Delhi ridge and Malani granites and rhyohtes are exposed at Tusham district Bhiwani just south of the region. These rocks take a northwest turn from Tusham and become submerged under the Punjab Plains only to get resurfaced at Kirana Hills Pakistan. The gravity data have delineated 6 km wide and 240 km long per shaped body under the Punjab plains covering the SW Punjab. The Tusham granites are high heat producing granites that is they are enriched in uranium, thorium and Potasium. The uranium concentration in Tusham granites is 8 to 11 .5 parts per million (ppm) as compared to the normal value of 4.5 in granites in general. The average crustal values is 2

Determination of trace uranium in human hair by nuclear track detection technique

International Nuclear Information System (INIS)

Chung, Yong Sam; Moon, Jong Hwa; En, Zinaida; Cho, Seung Yeon; Kang, Sang Hoon; Lee, Jae Ki

2001-01-01

The aim of this study is to describe a usefulness of nuclear analytical technique in assessing and comparing the concentration levels through the analysis of uranium using human hair sample in the field of environment. A fission track detection technique was applied to determine the uranium concentration in human hair. Hair samples were collected from two groups of people - a) workers not dealing with uranium directly, and b) workers possibly contaminated with uranium. The concentration of 235 U for the first group varied from <1 to 39 ng/g and the second group can be estimated up to the level of μg/g. Radiographs of heavy-duty work samples contained high dense 'hot spots' along a single hair. After washing in acetone and distilled water, external contamination was not totally removed. Insoluble uranium compounds were not completely washed out. The (n, f)-radiography technique, having high sensitivity, and capable of getting information on uranium content at each point of a single hair, is an excellent tool for environmental monitoring

Development, preparation and characterization of uranium molybdenum alloys for dispersion fuel application

Energy Technology Data Exchange (ETDEWEB)

Sinha, V.P. [Metallic Fuels Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)], E-mail: vedsinha@barc.gov.in; Prasad, G.J.; Hegde, P.V.; Keswani, R.; Basak, C.B.; Pal, S.; Mishra, G.P. [Metallic Fuels Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2009-04-03

Most of the research and test reactors worldwide have undergone core conversion from high enriched uranium base fuel to low enriched uranium base fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) program, which was launched in the late 1970s to reduce the risk of nuclear proliferation. To realize this goal, high density uranium compounds and {gamma}-stabilized uranium alloy powder were identified. In Metallic Fuels Division of BARC, R and D efforts are on to develop these high density uranium base alloys. This paper describes the preparation flow sheet for different compositions of Uranium and molybdenum alloys by an innovative powder processing route with uranium and molybdenum metal powders as starting materials. The same composition of U-Mo alloys were also fabricated by conventional method i.e. ingot metallurgy route. The U-Mo alloys prepared by both the methods were then characterized by XRD for phase analysis. The photomicrographs of alloys with different compositions prepared by powder metallurgy and ingot metallurgy routes are also included in the paper. The paper also covers the comparison of properties of the alloys prepared by powder metallurgy and ingot metallurgy routes.

Development, preparation and characterization of uranium molybdenum alloys for dispersion fuel application

International Nuclear Information System (INIS)

Sinha, V.P.; Prasad, G.J.; Hegde, P.V.; Keswani, R.; Basak, C.B.; Pal, S.; Mishra, G.P.

2009-01-01

Most of the research and test reactors worldwide have undergone core conversion from high enriched uranium base fuel to low enriched uranium base fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) program, which was launched in the late 1970s to reduce the risk of nuclear proliferation. To realize this goal, high density uranium compounds and γ-stabilized uranium alloy powder were identified. In Metallic Fuels Division of BARC, R and D efforts are on to develop these high density uranium base alloys. This paper describes the preparation flow sheet for different compositions of Uranium and molybdenum alloys by an innovative powder processing route with uranium and molybdenum metal powders as starting materials. The same composition of U-Mo alloys were also fabricated by conventional method i.e. ingot metallurgy route. The U-Mo alloys prepared by both the methods were then characterized by XRD for phase analysis. The photomicrographs of alloys with different compositions prepared by powder metallurgy and ingot metallurgy routes are also included in the paper. The paper also covers the comparison of properties of the alloys prepared by powder metallurgy and ingot metallurgy routes

Recovery of uranium from crude uranium tetrafluoride

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S K; Bellary, M P; Keni, V S [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author). 4 refs., 1 fig., 3 tabs.

Recovery of uranium from crude uranium tetrafluoride

International Nuclear Information System (INIS)

Ghosh, S.K.; Bellary, M.P.; Keni, V.S.

1994-01-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author)

Effect of molybdenum addition on metastability of cubic γ-uranium

International Nuclear Information System (INIS)

Sinha, V.P.; Hegde, P.V.; Prasad, G.J.; Dey, G.K.; Kamath, H.S.

2010-01-01

Over the years U 3 Si 2 compound dispersed in aluminium matrix has been used successfully as the potential low enriched uranium (LEU 235 ) base dispersion fuel for use in new research and test reactors and also for converting high enriched uranium (HEU > 85%U 235 ) cores to LEU for most of the existing research and test reactors world over, though maximum 4.8 g U cm -3 density is achievable with U 3 Si 2 -Al dispersion fuel. To achieve a uranium density of 8.0-9.0 g U cm -3 in dispersion fuel with aluminium as matrix material, it is required to use γ-stabilized uranium metal powders. At Bhabha Atomic Research Centre (BARC), R and D efforts are on to develop these high density uranium base alloys. This paper describes the alloying behaviour of uranium with varying amount of molybdenum. The U-Mo alloys with different molybdenum content have been prepared by using an induction melting furnace with uranium and molybdenum metal pellets as starting materials. U-Mo alloys with different molybdenum content were characterized by X-ray diffraction (XRD) for phase identification and lattice parameter measurements. The optical microstructure of different U-Mo alloy composition has also been discussed in this paper. Quantitative image analysis was also carried out to determine the amount of various phases in each composition.

Banco de ensayos para materiales piezoeléctricos en aplicaciones viales

Directory of Open Access Journals (Sweden)

de Frutos, J.

2011-04-01

Full Text Available The test bench system described in this paper performs experiments on piezoelectric materials used in road traffic applications, covering a range between 14 and 170 km/h, which is considered enough for testing under standard traffic conditions. A software has been developed to control the three phase induction motor driver and to acquire all the measurement data of the piezoelectric materials. The mass over each system’s axis can be selected, with a limit of 60 kg over each wheel. The test bench is used to simulate the real behaviour of buried piezoelectric cables in road traffic applications for both light and heavy vehicles. This new test bed system is a powerful research tool and can be applied to determine the optimal installation and configuration of the piezoelectric cable sensors and opens a new field of research: the study of energy harvesting techniques based on piezoelectric materials.

En este trabajo se define y propone un banco de ensayos que permite testar materiales piezoeléctricos para aplicaciones viales en sus diferentes configuraciones en un rango de velocidad entre los 14 y los 170 km/h, lo que cubre sobradamente las condiciones de tráfico real. Tanto el control del variador de velocidad del motor trifásico que realiza el accionamiento del banco, como la recogida de resultados de medida en las pruebas de excitación y de fatiga de los compuestos piezoeléctricos, se realiza de forma automatizada mediante código informatico. El peso que soporta cada eje del banco es configurable, permitiendo reproducir las señales obtenidas en aplicaciones donde los materiales piezoeléctricos actúan de sensores enterrados en la calzada para vehículos tanto pesados como ligeros. Gracias a esta nueva herramienta se facilita la investigación con materiales de este tipo en aplicaciones viales optimizando tanto el tipo como la disposición e instalación de los mismos, además de abrir el camino a la novedosa investigación sobre

Acute toxicity of uranium hexafluoride, uranyl fluoride and hydrogen fluoride

International Nuclear Information System (INIS)

Just, R.A.

1988-01-01

Uranium hexafluoride (UF 6 ) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO 2 F 2 ) and hydrogen fluoride (HF). Uranium compounds such as UF 6 and UO 2 F 2 exhibit both chemical toxicity and radiological effects, while HF exhibits only chemical toxicity. This paper describes the development of a methodology for assessing the human health consequences of a known acute exposure to a mixture of UF 6 , UO 2 F 2 , and HF. 4 refs., 2 figs., 5 tabs

Kinetic study of the thermal decomposition of uranium metaphosphate, U(PO{sub 3}){sub 4}, into uranium pyrophosphate, UP{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Yang, Hee-Chul, E-mail: nhcyang@kaeri.re.kr; Kim, Hyung-Ju; Lee, Si-Young; Yang, In-Hwan; Chung, Dong-Yong

2017-06-15

The thermochemical properties of uranium compounds have attracted much interest in relation to thermochemical treatments and the safe disposal of radioactive waste bearing uranium compounds. The characteristics of the thermal decomposition of uranium metaphosphate, U(PO{sub 3}){sub 4}, into uranium pyrophosphate, UP{sub 2}O{sub 7}, have been studied from the view point of reaction kinetics and acting mechanisms. A mixture of U(PO{sub 3}){sub 4} and UP{sub 2}O{sub 7} was prepared from the pyrolysis residue of uranium-bearing spent TBP. A kinetic analysis of the reaction of U(PO{sub 3}){sub 4} into UP{sub 2}O{sub 7} was conducted using an isoconversional method and a master plot method on the basis of data from a non-isothermal thermogravimetric analysis. The thermal decomposition of U(PO{sub 3}){sub 4} into UP{sub 2}O{sub 7} followed a single-step reaction with an activation energy of 175.29 ± 1.58 kJ mol{sup −1}. The most probable kinetic model was determined as a type of nucleation and nuclei-growth models, the Avrami-Erofeev model (A3), which describes that there are certain restrictions on nuclei growth of UP{sub 2}O{sub 7} during the solid-state decomposition of U(PO{sub 3}){sub 4}. - Highlights: •Thermal decomposition kinetics of U(PO{sub 3}){sub 4} into UP{sub 2}O{sub 7} was investigated. •The thermal decomposition followed a single-step reaction with an activation energy of 175.3 ± 1.6 kJ mol{sup −1}. •The most probable kinetic model was determined as a type of nucleation and nuclei-growth models, the Avrami-Erofeev (A3).

Aplicaciones del Just-In-Time en la Argentina

OpenAIRE

Enrique Yacuzzi; Carolina Fajntich; María Pía Romeo

2013-01-01

Este trabajo presenta el concepto de JIT (Just-In-Time, o justo a tiempo) y ofrece aplicaciones en la Argentina. En la Parte I, pone el JIT en el contexto de la gestión japonesa (management japonés): destaca las características de esta gestión, y resume su evolución a lo largo de las últimas décadas. Hace hincapié en la gestión de la producción y analiza los desafíos, críticas y las teorías de la convergencia con los sistemas occidentales que se han examinado a lo largo de los últimos 20 años...

Interest of uranium complexes for the mechanism study of the McMurry reaction

International Nuclear Information System (INIS)

Maury, O.

1997-01-01

The reducing coupling reactions of ketones in diols and olefins are generally carried out with titanium or samarium compounds. In this work uranium complexes have been used. They have allowed to study the chemical reaction mechanism. This thesis is divided into three parts: 1) the reduction mechanism of uranium tetrachloride by cyclic voltametry has been studied at first. It has been shown that this reduction is followed by a transfer reaction of chlorides between the reduced specie of the higher electronic density and UCl . 2) In the second part is described: the synthesis, the crystal structure, the reactivity of the chemical agents, the stereochemistry of diols and alkenes formation and the pinacolisation reaction catalysis. 3) In the last part, the limits of the McMurry reaction are given by the study of the aromatic ketones pinacolisation reaction by-products. The obtained results show that the complexes of the metals which present a high reducing and oxo-philic (Ti, Sm, U..) character react in a similar way with the carbonyl compounds. If the uranium compounds are less used than those of the titanium in the field of the organic synthesis applications, they are precious auxiliaries and excellent models for reactions mechanisms study and for the synthesis methods optimization. (O.M.)

Challenges of ICRP 60 for uranium refining and conversion facilities

International Nuclear Information System (INIS)

Takala, J.M.

1998-01-01

Cameco Corporation operates high-grade uranium mines in northern Saskatchewan and uranium refining and conversion facilities in Ontario. The dose limits for these and all other nuclear facilities in Canada are 50 mSv per year and 4 WLM per year, which are applied separately. However, the upcoming incorporation of the recommendations in ICRP 60 into the Canadian regulations will result in several important changes. In addition to a more restrictive dose limit, the new regulations will require that all radiation exposures be combined into a single index of exposure. Meeting the new lower dose limits of 50 mSv per year and 100 mSv per 5 years will not be a major problem at Cameco facilities. However, the incorporation of long-lived radioactive dust exposures into the dose calculation will be a major challenge. This will cause the most difficulty at the uranium refining and conversion facilities where much of the process involves handling a variety of uranium compounds in the form of a dry powder. At the uranium conversion facilities the control of exposure to airborne uranium is achieved through a combination of lung counting, urinalysis, and fixed area monitors. To progress from a system of exposure control to dose estimation to individual workers will require some major changes. (author)

Lung cancer among workers at a uranium processing plant

International Nuclear Information System (INIS)

Cookfair, D.L.; Beck, W.L.; Shy, C.; Lushbaugh, C.C.; Sowder, C.L.

1983-01-01

This study examined the risk of dying from lung cancer among white males who received radiation to the lung as a result of inhaling uranium dust or the dust of uranium compounds. Cases and controls were chosen from a cohort of workers employed in a uranium processing plant during World War II. Cumulative radiation lung dose among study population members ranged from 0 to 75 rads. Relative risk was found to increase with increasing level of exposure even after controlling for age and smoking status, but only for those who were over the age of 45 when first exposed. A statistically significant excess in risk was found for men in this age group with a cumulative lung dose of 20 rads of more. These data suggest that older age groups may be more susceptible to radiation-induced lung cancer than younger age groups

Laser separation of uranium isotopes

International Nuclear Information System (INIS)

Porter, J.T.

1981-01-01

Method and apparatus for separating uranium isotopes are claimed. The method comprises the steps of irradiating a uranyl source material at a wavelength selective to a desired isotope and at an effective temperature for isotope spectral line splitting below about 77 deg.K., further irradiating the source material within the fluorescent lifetime of the source material to selectively photochemically reduce the excited isotopic species, and chemically separating the reduced isotope species from the remaining uranyl salt compound

Analytical method of uranium (IV) and uranium (VI) in uranium ores and uranium-bearing rocks

International Nuclear Information System (INIS)

Shen Zhuqin; Zheng Yongfeng; Li Qingzhen; Zhong Miaolan; Gu Dingxiang

1995-11-01

The best conditions for keeping the original valences of uranium during the dissolution and separation procedure of geological samples (especially those micro uranium-bearing rock) were studied. With the exist of high concentration protectants, the sample was decomposed with concentration HF at 40 +- 5 degree C. The U(VI) was dissolved completely and formed stable complex UO 2 F 2 , the U(IV) was precipitated rapidly and carried by carrier. Quantitative separation was carried out immediately with suction. The decomposition of sample and separation of solid/liquid phases was completed within two minutes. After separation, the U(IV) and U(VI) were determined quantitatively with laser fluorescence or voltametry respectively according to the uranium content. The limit of detection for this method is 0.7 μg/g, RSD is 10.5%, the determinate range of uranium is 2 x 10 -6 ∼10 -1 g/g. The uranium contents and their valence state ratio were measured for more than one hundred samples of sand stone and granite, the accuracy and precision of these results are satisfactory for uranium geological research. (12 tabs.; 11 refs.)

Controlled synthesis of thorium and uranium oxide nano-crystals

International Nuclear Information System (INIS)

Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Gouder, Thomas; Courtois, Eglantine; Kubel, Christian; Meyer, Daniel

2013-01-01

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 nano-crystals 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 nano-crystals. The final characteristics of thorium and uranium oxide nano-crystals 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 nano-crystals with different sizes (4.5 and 10.7 nm) as well as branched nano-crystals (overall size ca. 5 nm), nano-dots (ca. 4 nm) and nano-rods (with ultra-small diameters of 1 nm) of thorium oxide were synthesised. (authors)

Reduction of uranium hexafluoride to uranium tetrafluoride

International Nuclear Information System (INIS)

Chang, I.S.; Do, J.B.; Choi, Y.D.; Park, M.H.; Yun, H.H.; Kim, E.H.; Kim, Y.W.

1982-01-01

The single step continuous reduction of uranium hexafluoride (UF 6 ) to uranium tetrafluoride (UF 4 ) has been investigated. Heat required to initiate and maintain the reaction in the reactor is supplied by the highly exothermic reaction of hydrogen with a small amount of elemental fluorine which is added to the uranium hexafluoride stream. When gases uranium hexafluoride and hydrogen react in a vertical monel pipe reactor, the green product, UF 4 has 2.5g/cc in bulk density and is partly contaminated by incomplete reduction products (UF 5 ,U 2 F 9 ) and the corrosion product, presumably, of monel pipe of the reactor itself, but its assay (93% of UF 4 ) is acceptable for the preparation of uranium metal with magnesium metal. Remaining problems are the handling of uranium hexafluoride, which is easily clogging the flowmeter and gas feeding lines because of extreme sensitivity toward moisture, and a development of gas nozzel for free flow of uranium hexafluoride gas. (Author)

Insertion compounds of transition-metal and uranium oxides

International Nuclear Information System (INIS)

Chippindale, A.M.; Dickens, P.G.; Powell, A.V.

1991-01-01

Several transition-metal and actinide oxides, in which the metal occurs in a high oxidation state, have open covalent structures and are capable of incorporating alkali and other electropositive metals under mild conditions to form insertion compounds A x MO n . These are solids which have several features in common: Over a range of compositions, A x MO n exists as one or more stable or metastable phases in which the structure of the parent oxide MO n is largely retained and the insertion element A is accommodated interstitially. Insertion is accompanied by a redox process A=A i . + e - M in which M is reduced and the electronic properties of the parent oxide change to those typical of a mixed-valence compound. The insertion process xA + MO n = A x MO n can be reversed, at least to some extent, by chemical or electrochemical reaction, with retention of structure (topotactic reaction). This review concentrates on methods of synthesis, characterisation, crystal structure and thermochemistry of these insertion compounds. It updates and extends previous work. (author)

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. The...

Uranium exploration

International Nuclear Information System (INIS)

De Voto, R.H.

1984-01-01

This paper is a review of the methodology and technology that are currently being used in varying degrees in uranium exploration activities worldwide. Since uranium is ubiquitous and occurs in trace amounts (0.2 to 5 ppm) in virtually all rocks of the crust of the earth, exploration for uranium is essentially the search of geologic environments in which geologic processes have produced unusual concentrations of uranium. Since the level of concentration of uranium of economic interest is dependent on the present and future price of uranium, it is appropriate here to review briefly the economic realities of uranium-fueled power generation. (author)

Uranium

International Nuclear Information System (INIS)

1982-01-01

The development, prospecting, research, processing and marketing of South Africa's uranium industry and the national policies surrounding this industry form the headlines of this work. The geology of South Africa's uranium occurences and their positions, the processes used in the extraction of South Africa's uranium and the utilisation of uranium for power production as represented by the Koeberg nuclear power station near Cape Town are included in this publication

Influence of uranium hydride oxidation on uranium metal behaviour

International Nuclear Information System (INIS)

Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

2013-01-01

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

Influence of uranium hydride oxidation on uranium metal behaviour

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

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

Uranium biomineralization by a metal resistant Pseudomonas aeruginosa strain isolated from contaminated mine waste.

Science.gov (United States)

Choudhary, Sangeeta; Sar, Pinaki

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(-1)cell dry wt.) following incubation in 100 mg U L(-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. Copyright © 2010 Elsevier B.V. All rights reserved.

Determination of uranium in phosphorite by radiometric measurements and activation analysis

International Nuclear Information System (INIS)

Santos Amaral, R. dos.

1987-01-01

Uranium was determined by passive gamma ray counting in phosphate rocks in the range from 50 to 400 ppm U 3 O 8 . The measurements were carried out focusing on the 186 KeV gamma ray from the 235 U nuclide. The radioactive equilibrium of the 226 Ra in the uranium decay chain was investigated due its contribution in the 186 KeV compound 226 Ra 235 U photopeak. Therefore a simulataneous uranium determination through the 234 Th radionuclide demonstrate the equilibrium conditions. The results of the uranium analysis by the following methods: spectrophotometry, XRF and delayed neutrons from three independent laboratories were compared to evaluate the accuracy of the radioanalytical results. The uranium content was also determined by neutron activation analysis, followed by gamma measurement of the 239 Np formed by the 238 U (n,γ) 239 U reaction and 239 U beta decay and the fission products of 235 U. By the correlation of 239 Np, 99 Mo, 143 Ce, 131 I, and 133 I photopeak was measured the 238 U/ 235 U isotopic ratio. (author) [pt

Uranium diphosphonates templated by interlayer organic amines

International Nuclear Information System (INIS)

Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Albrecht-Schmitt, Thomas E.; Ewing, Rodney C.

2013-01-01

The hydrothermal treatment of uranium trioxide and methylenediphosphonic acid with a variety of amines (2,2-dipyridyl, triethylenediamine, ethylenediamine, and 1,10-phenanthroline) at 200 °C results in the crystallization of a series of layered uranium diphosphonate compounds, [C 10 H 9 N 2 ]{UO 2 (H 2 O)[CH 2 (PO 3 )(PO 3 H)]} (Ubip2), [C 6 H 14 N 2 ]{(UO 2 ) 2 [CH 2 (PO 3 )(PO 3 H)] 2 ·2H 2 O} (UDAB), [C 2 H 10 N 2 ] 2 {(UO 2 ) 2 (H 2 O) 2 [CH 2 (PO 3 ) 2 ] 2 ·0.5H 2 O} (Uethyl), and [C 12 H 9 N 2 ]{UO 2 (H 2 O)[CH 2 (PO 3 )(PO 3 H)]} (Uphen). The crystal structures of the compounds are based on UO 7 units linked by methylenediphosphonate molecules to form two-dimensional anionic sheets in Ubip2 and UDAB, and one-dimensional anionic chains in Uethyl and Uphen, which are charge balanced by protonated amine molecules. Interaction of the amine molecules with phosphonate oxygens and water molecules results in extensive hydrogen bonding in the interlayer. These amine molecules serve both as structure-directing agents and charge-balancing cations for the anionic uranium phosphonate sheets and chains in the formation of the different coordination geometries and topologies of each structure. Reported herein are the syntheses, structural and spectroscopic characterization of the synthesized compounds. - Graphical abstract: The Raman spectra of the synthesized compounds and an illustration of the stacking of the layers with the diprotonated triethylenediamine molecules in [C 6 H 14 N 2 ]{(UO 2 ) 2 [CH 2 (PO 3 )(PO 3 H)] 2 ·2H 2 O} UDAB. Solvent water molecules are removed for clarity. The corresponding Raman spectra for the complexes synthesized is also shown. The structure is constructed from UO 7 pentagonal bipyramids (yellow), oxygen=red, phosphorus=magenta, carbon=black, and nitrogen=blue. Highlights: ► Organic amines act both as charge-balancing and as structure-directing agents. ► Extensive hydrogen bonding interactions with solvent water molecules and amines

Controlled thermolysis of uranium (alkoxy)siloxy complexes: a route to polymetallic complexes of Low-Valent uranium

Energy Technology Data Exchange (ETDEWEB)

Camp, Clement; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Kefalidis, Christos E.; Maron, Laurent [LPCNO, CNRS et INSA, UPS, Universite de Toulouse (France)

2013-07-01

Decomposition into higher species: Intramolecular U{sup III}-mediated homolytic C-O bond cleavage in U{sup III} (alkoxy)siloxy complexes at low temperature and subsequent reduction with KC{sub 8} led to unprecedented polymetallic complexes containing siloxy, silanediolate, and silanetriolate ligands. Such compounds may be useful precursors to uranium ceramics relevant for catalysis and the storage of spent nuclear fuel. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Disorder effects in strongly correlated uranium compounds

International Nuclear Information System (INIS)

Suellow, S.; Maple, M.B.; Tomuta, D.; Nieuwenhuys, G.J.; Menovsky, A.A.; Mydosh, J.A.; Chau, R.

2001-01-01

Moderate levels of crystallographic disorder can dramatically affect the ground-state properties of heavy fermion compounds. In particular, the role of disorder close to a quantum critical point has been investigated in detail. However, crystallographic disorder is equally effective in altering the properties of magnetically ordered heavy fermion compounds like URh 2 Ge 2 , where disorder-induced spin-glass behavior has been observed. In this system, moreover, the magnetic ground state can be tuned from a spin-glass to a long-range ordered antiferromagnetic one by means of an annealing treatment. The transformation of the magnetic state is accompanied by a transition in the transport properties from 'quasi-insulating' (dρ/dT 2 Ge 2 will be discussed. Of particular interest is the resistivity of as-grown URh 2 Ge 2 , which resembles the Non-Fermi-liquid system UCu 4 Pd, suggesting that a common mechanism - the crystallographic disorder - controls the transport properties of these materials

Hydroxyaromatic compounds of tantalum, tungsten, and the lighter actinides

International Nuclear Information System (INIS)

Gfaller, H.

1980-01-01

Some hydroxyaromatic compounds of the elements tantalum, tungsten, thorium and uranium were prepared as well as the basic materials for these synthesis processes, i.e. metal halides and metal alkoxides. The hydroxyaromatic compounds were studied by elemental analysis, IR spectroscopy, 1 H-NMR spectroscopy (if soluble in suitable solvents) and, in some cases, by X-ray fine structure analysis. (orig./EF) [de

Extracción y aplicaciones alimentarias de membranas de cáscaras de huevo

OpenAIRE

García Campos, Tania

2015-01-01

Caracterización físico-química de la membrana de la cáscara de huevo, seguida del estudio y desarollo de posibles aplicaciones de la membrana en diversos campos, entre los que destaca la formación de geles y la retención de cobre y proteínas.

X-Ray Fluorescence Spectrometry. II Determination of Uranium in ores; Espectrometria de fluorescencia de Rayos X. II-Aplicacion a la determinacion de uranio en minerales

Energy Technology Data Exchange (ETDEWEB)

Bermudez Polonio, J; Crus Castillo, F. de la; Fernandez Cellini, R

1961-07-01

A method of analysis of uranium in ores by X-ray spectrometry was developed, using the internal standard technique. Strontium was found to be the most suitable internal standard for general use. A Norelco Philips X-ray fluorescent spectrometer was used in this work, equipped with a lithium fluoride crystal acting as a diffraction grating analyzer. The intensity of the uranium-L {alpha}{sub 1} spectral line is calculated and related to corresponding strontium-K{sub {alpha}} spectral line, both detected with a Scintillation Counter. (Author) 31 refs.

Concentrations of heavy metals (lead, manganese, cadmium) in blood and urine of former uranium workers

International Nuclear Information System (INIS)

Apostolova, D.; Pavlova, S.; Paskalev, Z.

1999-01-01

Uranium ores contain heavy metals and other stable chemical elements as oxides, hydro-carbonates, sulphates, etc. During chemical processing of ore they could be transformed into compounds soluble in biologic liquids. The purpose of this study was to determine the combined intoxication of uranium miners and millers by heavy metals and radiation. Heavy metal (lead, manganese and cadmium) concentrations in blood and urine od 149 former uranium miners and millers were determined by AAS method. Data of significantly increased lead and manganese concentration in blood (p<0.05) of two groups were established in comparison with a control group. There is no statistical significant differences in the cadmium concentrations. The lead and manganese blood levels at the uranium millers were significant higher than those of the uranium miner group (p<0.05). Tendency towards increased blood lead concentrations of uranium millers depending on the length of service was established

Uranium

International Nuclear Information System (INIS)

Mackay, G.A.

1978-01-01

The author discusses the contribution made by various energy sources in the production of electricity. Estimates are made of the future nuclear contribution, the future demand for uranium and future sales of Australian uranium. Nuclear power growth in the United States, Japan and Western Europe is discussed. The present status of the six major Australian uranium deposits (Ranger, Jabiluka, Nabarlek, Koongarra, Yeelerrie and Beverley) is given. Australian legislation relevant to the uranium mining industry is also outlined

El papel de las variables sociodemográficas en el uso de las aplicaciones basadas en Internet por los Mayores

Directory of Open Access Journals (Sweden)

Begoña Peral Peral

2013-06-01

Full Text Available La población mundial está envejeciendo progresivamente. Se prevé que en 2050 el número de personas mayores de 60 años alcance los dos mil millones en el mundo. El empleo de las Tecnologías de la Información y Comunicación (TIC puede suponer para la población de mayor edad un impacto significativo en su calidad de vida, contribuyendo a conseguir mayores activos, disminuyendo la marginalización y el aislamiento social. Aunque existen diferencias importantes en el uso que los Mayores hacen de Internet y sus aplicaciones respecto al resto de la población, hay que considerar que este segmento no constituye un grupo homogéneo. Este trabajo busca comprobar si dentro del grupo de los Mayores existen diferencias en la frecuencia de uso de distintas aplicaciones basadas en Internet, en función de la edad, el sexo, el nivel de estudios alcanzados y la actividad laboral desarrollada en el pasado. Los resultados demuestran que existen diferencias significativas en el empleo de algunas aplicaciones en función de las variables sociodemográficas analizadas.

Análisis de Desarrollo de Software Orientado a Feature - Línea de Producto de Software para Aplicaciones de TVDI

Directory of Open Access Journals (Sweden)

Mirtha Fabiana Miranda

2015-08-01

Full Text Available El Desarrollo de Software Orientado a Features (FOSD consiste en la construcción de sistemas a partir de un conjunto de características, cada feature o característica es una unidad funcional que satisface un requisito de software. Las fases son análisis del dominio, diseño e implementación del dominio, configuración y generación del producto de software, obteniendo así una Línea de Productos de Software (SPL. El presente trabajo realiza una comparación de herramientas para su implementación y, se analiza un conjunto de aplicaciones que modelan features. Resultando un espacio de estudio abierto para modelar aplicaciones para la Televisión Digital Interactiva (TVDi. Además se han encontrado diversos métodos, artefactos y patrones de diseño para el modelado de una aplicación de TVDi en particular, reflejando un estudio para el modelado de variabilidad. El objetivo principal es estudiar SPL / FOSD, empleando los Patrones de Diseño de Interacción (PDI para el dominio de las aplicaciones de TVDi.

Protection of uranium by electrodeposition of nickel and diffusion

International Nuclear Information System (INIS)

Chauvin, G.; Coriou, H.; Hure, J.

1959-01-01

This work forms part of the overall scheme for investigating uranium canning for nuclear reactors. It is necessary to: - Protect the fuel (uranium) against corrosion by the cooling medium (heavy water, CO 2 , etc.), in the case of a rupture of the can; - Avoid dangerous U-Al diffusion (when it is question of an aluminium can) by using an intermediate layer of a metal whose rate of diffusion in uranium is very much less than that of aluminium under the same conditions. In the present work based on the use of an intermediate layer of nickel the following points are apparent: 1) After having treated the uranium surface it is possible to electroplate nickel on it in such a way that after annealing without the application of any pressure these deposits give a very good intermetallic U-Ni diffusion. Though this diffusion is inferior to that of the UAl system, it enables the protection to be reinforced and thus the corrosion resistance to be increased. 2) When no other factor varies, the experiments show that the quality of the diffusion zones obtained depends on the nature of the electrolytic nickel bath. 3) The classical nickel baths used previously for this type of work contain 20 to 40 g/l of boric acid acting as an electrolytic buffer. As a result of this, the deposits are highly contaminated by boron (400 to 500 ppm of boron). We shall show that with a bath which does not contain nuclear poisons, a very clean U-Ni diffusion zone can be obtained. 4) After annealing for 100 hours at 700 deg. C, microscopic examination of the diffusion front reveals the existence of five layers under bright field illumination and six Layers in polarised light: at least four of these layers are well crystallised. 5) Important irregularities in the interface between uranium and the first intermetallic compound U 6 Ni seem to be result of barriers to the diffusion caused by certain impurities in the uranium. 6) Of the seven definite compounds which can be formed during the diffusion, that

Determination of carbon in uranium and its compounds; Determinacion de carbono en uranio metal y sus compuestos

Energy Technology Data Exchange (ETDEWEB)

Perez-Garcia, M M

1972-07-01

This paper collects the analytical methods used our laboratories for the determination of carbon in uranium metal, uranate salts and the oxides, fluorides and carbides of uranium. The carbon is usually burned off in a induction or resistance oven under oxygen flow. The CO{sub 2} is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

Czechoslovak uranium

International Nuclear Information System (INIS)

Pluskal, O.

1992-01-01

Data and knowledge related to the prospecting, mining, processing and export of uranium ores in Czechoslovakia are presented. In the years between 1945 and January 1, 1991, 98,461.1 t of uranium were extracted. In the period 1965-1990 the uranium industry was subsidized from the state budget to a total of 38.5 billion CSK. The subsidies were put into extraction, investments and geologic prospecting; the latter was at first, ie. till 1960 financed by the former USSR, later on the two parties shared costs on a 1:1 basis. Since 1981 the prospecting has been entirely financed from the Czechoslovak state budget. On Czechoslovak territory uranium has been extracted from deposits which may be classified as vein-type deposits, deposits in uranium-bearing sandstones and deposits connected with weathering processes. The future of mining, however, is almost exclusively being connected with deposits in uranium-bearing sandstones. A brief description and characteristic is given of all uranium deposits on Czechoslovak territory, and the organization of uranium mining in Czechoslovakia is described as is the approach used in the world to evaluate uranium deposits; uranium prices and actual resources are also given. (Z.S.) 3 figs

Uranium in Niger; L'uranium au Niger

Energy Technology Data Exchange (ETDEWEB)

Gabelmann, E

1978-03-15

This document presents government policy in the enhancement of uranium resources, existing mining companies and their productions, exploitation projects and economical outcome related to the uranium mining and auxiliary activities. [French] Le document presente la politique de l'Etat dans le cadre de la mise en valeur des ressources d'uranium, les societes minieres existantes et leurs productions, les projets d'exploitation d'uranium et les retombees economiques liees aux activites uraniferes et connexes.

Laser fluorimetric analysis of uranium in water from Vishakhapatnam and estimation of health risk

International Nuclear Information System (INIS)

Bhangare, R.C.; Tiwari, M.; Ajmal, P.Y.; Sahu, S.K.; Pandit, G.G.

2014-01-01

Uranium is a naturally occurring radioactive element that is both radiologically and chemically toxic. The presence of uranium in the aquatic environment is due to the leaching from natural deposits, release in mill tailings, the combustion of coal and other fuels, and the use of phosphate fertilizers that contain uranium up to a concentration of 150g g -1 and contribute to ground water pollution. The most prevalent states of uranium are the hexavalent and tetravalent. The hexavalent state of uranium is particularly important in water because of the insolubility of almost all tetravalent compounds. Uranium enters into human tissues mainly through drinking water, food, air and other occupational and accidental exposures. Intake of uranium through air and water is normally low, but in circumstances in which uranium is present in a drinking water source the majority of intake can be through drinking water. Seeing potential health hazards from natural radionuclides in consuming water, many countries worldwide adopted the guideline activity concentration for drinking water quality recommended by the WHO (2011). For uranium WHO has set limit for drinking water to 30μgL -1 . The main purpose of this study was to measure the level of uranium in drinking water samples from the health hazard point of view and to observe the trend in the variation of uranium content in drinking water from upcoming BARC site at Vishakhapatnam area

Contribution to the study of renal load and its therapeutic modifications during acute uranium contaminations

International Nuclear Information System (INIS)

Bourguignon, M.H.N.

1977-01-01

The renal load during acute experimental contaminations in rats and the possible effects of treatment with chelators (DTPA) and bicarbonates are estinated. The following points are examined in turn: kidney uptake of uranyl nitrate and therapeutic tests; in vitro solubility of oxides UO 3 and U 3 O 8 in synthetic serum, their kidney uptake and therapeutic tests. The experimental values of the in vitro uranium oxide dissolution method were checked against in vivo observations. These experiments lead to the following conclusions: concerning the solubility of uranium compounds the strong solubility of UO 3 and much lesser solubility of U 3 O 8 in biological media are confirmed; with regard to the kidney uptake of uranium derivatives the fixation is proportional to the amount injected when the compound (uranyl nitrate) is soluble, which would correspond to the dissolved fraction in the case of more or less insoluble oxide. The right-left uptake is symmetrical. The therapeutic conclusions are as follows: the effectiveness of DTPA, in clearing the organism, especially from bone contamination is proved, but the renal uranium load is neither increased nor reduced; single injections of bicarbonates appear to reduce the kidney load in cases of U 3 O 8 contamination but are ineffective for UO 3 and UO 2 ++ . This difference may be explained by the low circulating concentration, due to weak contamination and low solubility, of U 3 O 8 as compared with the other two compounds [fr

Characterization and classification of uranium ore concentrates (yellow cakes) using infrared spectrometry

Energy Technology Data Exchange (ETDEWEB)

Varga, Z.; Oeztuerk, B.; Mayer, K.; Wallenius, M.; Apostolidis, C. [Joint Research Centre, Karlsruhe (Germany). Inst. for Transuranium Elements; Meppen, M. [Carl Friedrich von Weizsaecker-Zentrum fuer Naturwissenschaft und Friedensforschung, Hamburg (Germany)

2011-07-01

In this work the applicability of Fourier-transform infrared spectrometry (FTIR) for nuclear forensic studies of uranium ore concentrates (UOC) are investigated. The technique was used for the identification of the type of uranium compound and various process-related impurities, which can give information on the production method of the material. The measured spectra were evaluated also by statistical means, using the soft independent modelling of class analogy (SIMCA) technique to reveal less apparent similarities between the measured UOC samples.

Mining and processing of uranium ores in the USSR

International Nuclear Information System (INIS)

Laskorin, B.N.; Mamilov, V.A.; Korejsho, Yu.A.

1983-01-01

Experience gained in uranium ore mining by modern methods in combination with underground and heap leaching is summarized. More intensive processing of low-grade ores has been achieved through the use of autoclave leaching, sorptive treatment of thick pulps, extractive separation of pure uranium compounds, automated continuous sorption devices of high efficiency for processing the underground- and heap-leaching liquors, natural and mine water, and recovery of molybdenum, vanadium, scandium, rare earths and phosphate fertilizers from low-grade ores. Production of ion-exchangers and extractants has been developed and processes for concomitant recovery of copper, gold, ionium, tungsten, caesium, zirconium, tantalum, nickel and cobalt have been designed. (author)

Uranium ores

International Nuclear Information System (INIS)

Poty, B.; Roux, J.

1998-01-01

The processing of uranium ores for uranium extraction and concentration is not much different than the processing of other metallic ores. However, thanks to its radioactive property, the prospecting of uranium ores can be performed using geophysical methods. Surface and sub-surface detection methods are a combination of radioactive measurement methods (radium, radon etc..) and classical mining and petroleum prospecting methods. Worldwide uranium prospecting has been more or less active during the last 50 years, but the rise of raw material and energy prices between 1970 and 1980 has incited several countries to develop their nuclear industry in order to diversify their resources and improve their energy independence. The result is a considerable increase of nuclear fuels demand between 1980 and 1990. This paper describes successively: the uranium prospecting methods (direct, indirect and methodology), the uranium deposits (economical definition, uranium ores, and deposits), the exploitation of uranium ores (use of radioactivity, radioprotection, effluents), the worldwide uranium resources (definition of the different categories and present day state of worldwide resources). (J.S.)

Metal electrodeposition and electron transfer studies of uranium compounds in room temperature ionic liquids

International Nuclear Information System (INIS)

Stoll, M.E.; Oldham, W.J.; Costa, D.A.

2004-01-01

Room temperature ionic liquids (RTIL's) comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and one of several anions such as PF 6 - , BF 4 - , or - N(SO 2 CF 3 ) 2 , represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. Part of the intrigue with RTIL's stems from some of their inherent solvent properties including negligible vapor pressure, good conductivity, high chemical and thermal stability, and non-flammability. Additionally, a substantial number of RTIL's can be envisioned simply by combining different cation and anion pairs, thereby making them attractive for specific application needs. We are interested in learning more about the possible use of RTIL's within the nuclear industry. In this regard our research team has been exploring the electron transfer behavior of simple metal ions in addition to coordination and organometallic complexes in these novel solvents. Results from our research have also provided us with insight into the bonding interactions between our current anion of choice, bis(trifluoromethylsulfonyl)imide = NTf 2 , and open coordination sites on actinide and transition metal fragments. This presentation will focus on recent results in two areas: the electrodeposition of electropositive metal ions from RTIL solutions and the electron transfer behavior for several uranium complexes. Details concerning the cathodic electrodeposition and anodic stripping of alkali metals (Na, K) from various working electrode surfaces (Pt, Au, W, Glassy Carbon) will be discussed. Figure 1 displays typical behavior for the electrodeposition of potassium metal from an RTIL containing potassium ions produced through the reaction of KH with H[NTf 2 ]. Our efforts with other metal ions, including our results to date with uranium electrodeposition, will be covered during the presentation. The electron transfer behavior for a number of uranium complexes have been studied with various

Recent developments in the dissolution and automated analysis of plutonium and uranium for safeguards measurements

International Nuclear Information System (INIS)

Jackson, D.D.; Marsh, S.F.; Rein, J.E.; Waterbury, G.R.

1975-01-01

The status of a program to develop assay methods for plutonium and uranium for safeguards purposes is presented. The current effort is directed more toward analyses of scrap-type material with an end goal of precise automated methods that also will be applicable to product materials. A guiding philosophy for the analysis of scrap-type materials, characterized by heterogeneity and difficult dissolution, is relatively fast dissolution treatment to effect 90 percent or more solubilization of the uranium and plutonium, analysis of the soluble fraction by precise automated methods, and gamma-counting assay of any residue fraction using simple techniques. A Teflon-container metal-shell apparatus provides acid dissolutions of typical fuel cycle materials at temperatures to 275 0 C and pressures to 340 atm. Gas--solid reactions at elevated temperatures separate uranium from refractory materials by the formation of volatile uranium compounds. The condensed compounds then are dissolved in acid for subsequent analysis. An automated spectrophotometer is used for the determination of uranium and plutonium. The measurement range is 1 to 14 mg of either element with a relative standard deviation of 0.5 percent over most of the range. The throughput rate is 5 min per sample. A second-generation automated instrument is being developed for the determination of plutonium. A precise and specific electroanalytical method is used as its operational basis. (auth)

Uranium and thorium based phosphate matrix: synthesis, characterizations and lixiviation

International Nuclear Information System (INIS)

Dacheux, N.

1995-03-01

In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO 2 )(PO 4 ) 2 , U 2 O(PO 4 ) 2 , UCIPO 4 , 4H 2 O, and Th 4 (PO 4 ) 4 P 2 O 7 . Experimental evidenced are advanced for non existent compounds such as: U 3 (PO 4 ) 4 , U 2 O 3 P 2 O 7 and Th 3 (PO 4 ) 4 . Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO 2 )(PO 4 ) 2 has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U 4+ and UO 2 2+ ions are ordered in pairs along parallel chains according to a new type of arrangement. Reaction mechanism, starting from UCIPO 4 , 4H 2 O and based on redox processes of uranium in solid state was set up. From two main matrices U(UO 2 )(PO 4 ) 2 and Th 4 (PO 4 ) 4 P 2 O 7 , solid solutions were studied. They consist of replacement of U(IV) by Th(IV) and reversely. The leaching tests on pure, loaded and doped matrices were performed in terms of storage time, pH of solutions, and determined by the use of solids labelled with 230 U or by the measurement of uranyl concentration by Laser-Induced Time-Resolved Spectro-fluorimetry. Average concentration of uranium in the liquid phase is around 10 -4 M to 10 -6 M. Taking into account the very low solubilities of the studied phosphate ceramics, we estimated their chemical performances promising as an answer to the important nuclear waste problem, if we compare them to the glasses used at the present time. (author)

Techniques of uranium mineralization alteration remote sensing information identification and its application in Taoshan area, Jiangxi province

International Nuclear Information System (INIS)

Xuan Yanxiu; Zhang Jielin

2010-01-01

Based on the spectrum characteristics analysis of uranium mineralization alteration rocks and minerals, and using satellite multi-spectral remote sensing image data as the main information sources, multiple remote sensing data processing techniques and methods such as color compound, band ratio, principal component analysis and image color segmentation, are synthetically applied to extract uranium mineralization and alteration information from the remote sensing image. The results of this study provided basic data for analysis of uranium ore-formation conditions in the area. (authors)

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

On the technical development to minimize the quantity of solid wastes in a uranium conversion

International Nuclear Information System (INIS)

Otomura, Keiichiro; Ogura, Yoshikazu; Fujisaki, Sakae

1987-01-01

We have developed the new process of treating the waste liquor from a uranium conversion at Ningyo Toge Works PNC, Japan. This process consists of neutralizing precipitation, solid liquid separation, distillation and adsorption. At a neutralizing precipitation step a magnesium oxide is added in the waste liquor containing uranium and fluorine. Most of the uranium and fluorine in the waste liquor precipitate as magnesium compounds. A sulfuric acid is added to the precipitate separated by a filter to dissolve. The resulting solution is then distilled to recover a hydrofluoric acid as a distillate. Uranium is recovered from a residue by an anion exchange method. The recoverd fluorine and uranium are recycled to the main process of conversion. The filtrate separated at the precipitation step is then passed through adsorbing columns. The residual fluorine and uranium in the filtrate were adsorbed and removed by the chelating resine which selectively adsorb the uranium and fluorine. After that the treated waste liquor is discharged out of the plant. This process has merits of being able to minimize the quantity of solid waste in comparison with the conventional process and to recover uranium and fluorine. This process can also be applied to uranium reconversion process from uranium hexafluoride to uranium oxide and to uranium metal production process, which produce the same kind of waste liquor. (author)

Thermodynamic analysis and experimental study on the chlorination of uranium oxide by gas-solid reaction

International Nuclear Information System (INIS)

Shin, Y.J.; Kim, I.S.; Shin, H.S.; Ro, S.G.; Park, H.S.

1998-01-01

In order to determine the operating condition of an uranium chlorination process with U 3 O 8 -C-Cl 2 system, the experimental conditions have been evaluated preliminarily by the thermochemical analysis and experimentally confirmed in this study. The dry-type chlorination of U 3 O 8 occurs as irreversible and exothermic reaction and produces many kinds of chloride compounds such as UCl 3 , UCl 4 , UCl 5 , and UCl 6 in the air and humidity controlled argon environment. Taking account of Gibbs free energy and vapor pressure for various chloride compounds, the proper temperature range of chlorination appears to be 863 to 953 K in aspects of increasing reaction rate and the yield of nonvolatile product. In the course of the experimental confirmation the powder of U 3 O 8 is perfectly converted into uranium chlorides within 4 hours above 863 K, and then the maximum fraction of uranium chloride remaining in the reactor is about 30% of total conversion mass. (author)

Pengaruh Kandungan Uranium Dalam Umpan Terhadap Efisiensi Pengendapan Uranium

OpenAIRE

Torowati

2010-01-01

PENGARUH KANDUNGAN URANIUM DALAM UMPAN TERHADAP EFISIENSI PENGENDAPAN URANIUM. Setiap aktivitas analisis di Laboratorium Kendali Kualitas, Bidang Bahan Bakar Nuklir selalu dihasilkan limbah radioaktif cair. Limbah radioaktif cair di laboratorium masih mengandung uranium yang cukup besar ± 0,600 g U/l dengan keasamaan yang cukup besar pula. Karena uranium mempunyai nilai ekonomis yang cukup tinggi maka perlu USAha untuk mengambil kembali uranium tersebut. Pada kegiatan ini telah dilak...

Glances on uranium. From uranium in the earth to electric power

International Nuclear Information System (INIS)

Valsardieu, C.

1995-01-01

This book is a technical, scientific and historical analysis of the nuclear fuel cycle from the origin of uranium in the earth and the exploitation of uranium ores to the ultimate storage of radioactive wastes. It comprises 6 chapters dealing with: 1) the different steps of uranium history (discovery, history of uranium chemistry, the radium era, the physicists and the structure of matter, the military uses, the nuclear power, the uranium industry and economics), 2) the uranium in nature (nuclear structure, physical-chemical properties, radioactivity, ores, resources, cycle, deposits), 3) the sidelights on uranium history (mining, prospecting, experience, ore processing, resources, reserves, costs), 4) the uranium in the fuel cycle, energy source and industrial product (fuel cycle, fission, refining, enrichment, fuel processing and reprocessing, nuclear reactors, wastes management), 5) the other energies in competition and the uranium market (other uranium uses, fossil fuels and renewable energies, uranium market), and 6) the future of uranium (forecasting, ecology, economics). (J.S.)

Uranium prospecting; La prospection de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Roubault, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

This report is an instruction book for uranium prospecting. It appeals to private prospecting. As prospecting is now a scientific and technical research, it cannot be done without preliminary studies. First of all, general prospecting methods are given with a recall of fundamental geologic data and some general principles which are common with all type of prospecting. The peculiarities of uranium prospecting are also presented and in particular the radioactivity property of uranium as well as the special aspect of uranium ores and the aspect of neighbouring ores. In a third part, a description of the different uranium ores is given and separated in two different categories: primary and secondary ores, according to the place of transformation, deep or near the crust surface respectively. In the first category, the primary ores include pitchblende, thorianite and rare uranium oxides as euxenite and fergusonite for example. In the second category, the secondary ores contain autunite and chalcolite for example. An exhaustive presentation of the geiger-Mueller counter is given with the presentation of its different components, its functioning and utilization and its maintenance. The radioactivity interpretation method is showed as well as the elaboration of a topographic map of the measured radioactivity. A brief presentation of other detection methods than geiger-Mueller counters is given: the measurement of fluorescence and a chemical test using the fluorescence properties of uranium salts. Finally, the main characteristics of uranium deposits are discussed. (M.P.)

Spectrophotometric and spectrofluorometric determination of uranium using a flotation process with benzoate and rivanol

Energy Technology Data Exchange (ETDEWEB)

Lopez Herroz, C.; Hernandez, M.; Sanchez-Pedreno, C.

1988-01-01

Tribenzouranyl anion forms with rivnol an ion-association compound which is floated with isopropyl ether and dissolved in ethanol. As a consequence, new spectrophotometric and spectrofluorimetric methods for the determination of trace amounts of uranium are developed. At 373 nm Beer's law is obeyed over the range 10-150 /mu/g of uranium. When the spectrofluorimetric technique is used, calibration graph is linear in the 2-25 /mu/g range.

Single nanocrystals of uranium dicarbide encapsulated in carbon

International Nuclear Information System (INIS)

Pasqualini, Enrique; Adelfang, Pablo

1996-01-01

The simultaneous volatilization of carbon and uranium compounds in an inert atmosphere produces the encapsulation of uranium dicarbide in graphitic material. These composite particles are of nanoscopic dimensions (smaller than 100 nanometers) and have the appearance of a black soot. Nanocapsules are as chemically inert as graphite and providers a more secure handling and processing of nuclear toxic materials. They preserve uranium dicarbide from environmental decomposition. The kernel of the nanoparticles is a single crystal of uranium dicarbide. The covers of the crystal are of graphitic structures of two types: parallel graphite layers and randomly oriented graphite crystallites. Both type of covers surround the UC 2 nanocrystal kernel. Density separation and measurements of specific area (BET technique) of purified soot were done. Particular adsorption and desorption kinetics of nitrogen monolayers indicate the presence of nanoparticles agglomeration. This is confirmed by direct observation by transmission electron microscopy (TEM). From density measurement and high resolution transmission electron microscopy (HRTEM) observation it can be inferred that there are gaps between kernel and cover and probably closed porosity inside clusters. Raman spectroscopy indicates only the presence of graphitic type carbon. Rietveld refinement of the nanoencapsulated material helps in the interpretation of X-Ray diffraction spectra. (author)

Single nanocrystals of uranium dicarbide encapsulated in carbon

Energy Technology Data Exchange (ETDEWEB)

Pasqualini, Enrique; Adelfang, Pablo [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Dept. de Combustibles Nucleares

1996-07-01

The simultaneous volatilization of carbon and uranium compounds in an inert atmosphere produces the encapsulation of uranium dicarbide in graphitic material. These composite particles are of nanoscopic dimensions (smaller than 100 nanometers) and have the appearance of a black soot. Nanocapsules are as chemically inert as graphite and providers a more secure handling and processing of nuclear toxic materials. They preserve uranium dicarbide from environmental decomposition. The kernel of the nanoparticles is a single crystal of uranium dicarbide. The covers of the crystal are of graphitic structures of two types: parallel graphite layers and randomly oriented graphite crystallites. Both type of covers surround the UC{sub 2} nanocrystal kernel. Density separation and measurements of specific area (BET technique) of purified soot were done. Particular adsorption and desorption kinetics of nitrogen monolayers indicate the presence of nanoparticles agglomeration. This is confirmed by direct observation by transmission electron microscopy (TEM). From density measurement and high resolution transmission electron microscopy (HRTEM) observation it can be inferred that there are gaps between kernel and cover and probably closed porosity inside clusters. Raman spectroscopy indicates only the presence of graphitic type carbon. Rietveld refinement of the nanoencapsulated material helps in the interpretation of X-Ray diffraction spectra. (author)