Pre-concentration of uranium from water samples by dispersive liquid-liquid micro-extraction

International Nuclear Information System (INIS)

Khajeh, Mostafa; Nemch, Tabandeh Karimi

2014-01-01

In this study, a simple and rapid dispersive liquid-liquid microextraction (DLLME) was developed for the determination of uranium in water samples prior to high performance liquid chromatography with diode array detection. 1-(2-pyridylazo)-2-naphthol (PAN) was used as complexing agent. The effect of various parameters on the extraction step including type and volume of extraction and dispersive solvents, pH of solution, concentration of PAN, extraction time, sample volume and ionic strength were studied and optimized. Under the optimum conditions, the limit of detection (LOD) and preconcentration factor were 0.3 μg L -1 and 194, respectively. Furthermore, the relative standard deviation of the ten replicate was <2.6%. The developed procedure was then applied to the extraction and determination of uranium in the water samples.

On-line solid phase extraction using ion-pair microparticles combined with ICP-OES for the simultaneous preconcentration and determination of uranium and thorium

Energy Technology Data Exchange (ETDEWEB)

Yousefi, Seyed Reza; Zolfonoun, Ehsan [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). NFCRS

2016-07-01

In this work, after on-line and in-situ solid phase extraction technique was used for the extraction and preconcentration of uranium and thorium from aqueous samples prior to inductively coupled plasma optical emission spectrometry (ICP-OES) determination. In this method, sodium hexafluorophosphate (as an ion-pairing agent) was added to the sample solution containing the cationic surfactant (dodecyltrimethylammonium bromide) and the complexing agent (dibenzoylmethane). A cloudy solution was formed as a result of formation of an ion pair between surfactant and hexafluorophosphate. The solid microparticles were passed through a microcolumn filter and the adsorbed microparticles were subsequently eluted with acid, which was directly introduced into the ICP-OES nebulizer. The main variables affecting the pre-concentration and determination steps of uranium and thorium were studied and optimized. Under the optimum conditions, the enhancement factors of 97 and 95 and the detection limits of 0.52 and 0.21 μg L{sup -1} were obtained for uranium and thorium, respectively.

Refining of crude uranium by solvent extraction for production of nuclear pure uranium metal

International Nuclear Information System (INIS)

Gupta, S.K.; Manna, S.; Singha, M.; Hareendran, K.N.; Chowdhury, S.; Satpati, S.K.; Kumar, K.

2007-01-01

Uranium is the primary fuel material for any nuclear fission energy program. Natural uranium contains only 0.712% of 235 U as fissile constituent. This low concentration of fissile isotope in natural uranium calls for a very high level of purity, especially with respect to neutron poisons like B, Cd, Gd etc. before it can be used as nuclear fuel. Solvent extraction is a widely used technique by which crude uranium is purified for reactor use. Uranium metal plant (UMP), BARC, Trombay is engaged in refining of uranium concentrate for production of nuclear pure uranium metal for fabrication of fuel for research reactors. This paper reviews some of the fundamental aspects of this refining process with some special references to UMP, BARC. (author)

Preconcentration of low grade uranium ores by gravity and magnetic methods: a case study with copper tailings from Singhbhum, Bihar, India

International Nuclear Information System (INIS)

Natarajan, R.; Sreenivas, T.; Krishna Rao, N.

1992-01-01

The physical beneficiation methods applied to uranium ores are gravity and magnetic techniques. Feasibility of application of these two techniques has been industrially demonstrated in the case of Palabora copper-uranium ores and Witwatersrand gold-uranium ores respectively. In India exhaustive studies have been carried out on the application of gravity and magnetic methods for preconcentration of uranium values from tailings of copper plants at Surda, Rakha and Mosabani in Singhbhum. While recovery by shaking tables is poor owing to non-liberation and inefficient recovery in finer particle sizes (-37μm), gravity machines like Bartles Mozely Separator and Bartles Cross Belt Concentrator are able to give improved recovery in sizes down to about 15μm. Application of Wet High Intensity Magnetic Separator (WHIMS) is able to improve the recovery to about 75 to 85% from the three tailings, and the improvement is due to the ability of WHIMS collect the micaceous mineral particles containing composite uranium values, as well as uraninite particles down to about 10μm in size. WHIMS is inefficient in recovering uraninite particles below 5μm. High Gradient Magnetic Separator and Super Conducting High Gradient Magnetic Separator, on the other hand, are able to give enhanced recovery of even < 5μm uraninite particles. With the improved technology of gravity and magnetic methods now available, it should now be techno-economically feasible to employ preconcentration of low tenor uranium ores by physical beneficiation, prior to chemical processing. (author). 25 refs. 8 figs, 5 tabs

Determination of uranium in natural waters and high-purity aluminum by flow-injection on-line preconcentration and ICP-MS detection

International Nuclear Information System (INIS)

Seki, Tatsuya; Oguma, Koichi

2004-01-01

A flow injection method has been developed for the determination of uranium is natural waters and high-purity aluminum by use of on-line preconcentration on a U/TEVA TM column and ICP-MS detection. The sample solution prepared as a nitric acid solution in 3 mol l -1 was passed through the U/TEVA TM column to collect uranium and uranium adsorbed was eluted with 0.1 mol l -1 nitric acid. The effluent was introduced directly into the nebulizer of the ICP-MS and 238 U was measured. The detection limit, calculated as 3-times the standard deviation of the background noise, was 3pg and the sample throughput was about 10 per hour. The proposed method was successfully applied to the determination of uranium in river-water reference materials, a seawater reference material and high-purity aluminum reference materials. (author)

Use of open-cell resilient polyurethane foam loaded with crown ether for the preconcentration of uranium from aqueous solutions

International Nuclear Information System (INIS)

Abou-Mesalam, M.M.; El-Naggar, I.M.; Abdel-Hai, M.S.; El-Shahawi, M.S.

2003-01-01

The preconcentration of uranium from aqueous solutions on open-cell resilient polyurethane foams (PUF) impregnated with crown ether as an organic extractant in different conditions was investigated. The data showed that 50 minutes is a sufficient time to attain equilibrium with a maximum extraction percentage for uranium ion on polyurethane foams loaded with crown ether. Also the extraction percentage of uranium is increased markedly with increasing the pH values up to pH ∼ 6 and displayed the lowest extraction at 8 > pH > 6. The different isotherms of uranium sorption have shown that the sorption followed a Freundlich isotherm. Column studies have been carried out in order to extend these studies to the plant scale. From the data of column sorption and breakthrough curves, the height equivalent of theoretical plates (HETP), and breakthrough capacity which affect the efficiency of the column have been calculated and found to be 1.03 mm/plate, 64 ± 5 and 58.3 mg uranium/gram polyurethane foam impregnated with crown ether, respectively. (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

Collection/concentration of trace uranium for spectrophotometric detection using activated carbon and first-derivative spectrophotometry

International Nuclear Information System (INIS)

El-Sayed, A.A.; Hamed, M.M.; El-Reefy, S.; Hmmad, H.A.

2007-01-01

The need exists for preconcentration of trace and ultratrace amounts of uranium from environmental, geological and biological samples. The adsorption of uranium on various solids is important from the purification, environmental, and radioactivity waste disposal points of view. A method is described for the determination of traces of uranium using first-derivative spectrophotometry after adsorptive preconcentration of uranium on activated carbon. Various parameters that influence the adsorptive preconcentration of uranium on activated carbon, viz., pH, amounts of activated carbon and time of stirring and interference of metals have been studied. First-derivative spectrophotometry in conjunction with adsorptive preconcentration of uranium on activated carbon is used for determining uranium at concentration levels down to 20 ppb (w/v). (orig.)

Combination of solid phase extraction and dispersive liquid–liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination

International Nuclear Information System (INIS)

Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

2013-01-01

Graphical abstract: Pass the sample through the basic alumina column ⇒ elute retained uranium along with the cations ⇒ convert the uranium to its anionic benzoate complex ⇒ extract its ion pair with malachite green into small volume of chloroform by DLLME ⇒ measure its absorption at 621 nm using fiber optic-linear array detection spectrophotometry. -- Highlights: • By combination of SPE and DDLME a high preconcentration factor of 2500 was obtained. • Development of SPE-DDLME-Spectrophotometric method for det. of trace amounts of uranium. • Ultra trace amount of uranium in water samples was det. by the proposed method. • The detection limit of the proposed method is comparable to the most sensitive method. • The proposed method is a free interference spectrophotometric method for uranium det. -- Abstract: A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid–liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L −1 ) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid–liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L −1 , and a relative standard deviation of 4.1% (n = 6) at 400 ng L −1 were obtained. The method was

Synthesis of xanthate functionalized silica gel and its application for the preconcentration and separation of uranium(VI) from inorganic components

International Nuclear Information System (INIS)

Gopi Krishna, P.; Naidu, G.R.K.; Rao, K.S.

2005-01-01

A new chelating solid extractant prepared by the chemical immobilization of xanthate on silica gel was characterized by Fourier transform infra red spectrometry (FTIR), thermogravimetric analysis (TGA) and microanalysis and used for the preconcentration and separation of uranyl ion prior to its determination by Arsenazo-III. The effect of pH, weight of the solid extractant, volume of the aqueous phase and the interference of neutral electrolytes, cations and anions on the determination of uranium, have been studied in detail to optimize the conditions for trace determination of uranium(VI). The accuracy of the developed procedure was tested by analyzing marine sediment (MESS-3) and soil (IAEA-SOIL-7) reference materials. The results obtained on analysis of soil and sediment samples are comparable to standard ICP-MS values. (author)

Preparation of 1-(2-pyridylazo)-2-naphthol functionalized benzophenone/naphthalene and their uses in solid phase extractive preconcentration/separation of uranium(VI)

International Nuclear Information System (INIS)

Preetha, C.R.; Prasada Rao, T.

2003-01-01

The preparation of solid reagent 1-(2-pyridylazo)-2-naphthol functionalized benzophenone/naphthalene for preconcentration/separation of uranium(VI) is described. These reagents enriches uranium(VI) quantitatively from dilute aqueous solutions in the pH range 10.5-11.0. The solid mixture consisting of the enriched metal ion along with solid phase extractant were dissolved in 2 ml of acetone and uranium(VI) content was established spectrophotometrically by using Arsenazo III procedure. Calibration graphs were rectilinear over the uranium(VI) concentration in the range 0.002-0.1 μg cm -3 . Five replicate determinations of 40 μg of uranium present in 1 dm 3 of sample solution gave a mean absorbance of 0.185 with a relative standard deviation of 1.4%. The detection limit (corresponding to 3 times the standard deviation of the blank) and the enrichment factor were found to be 2 μg dm -3 and 500 respectively. Further the possible separation of uranium(VI) from several bivalent, trivalent and tetravalent elements was also established. In addition to validating the developed method by successfully analysing marine sediment reference material (MESS-3), uranium content was established in soil, river and marine sediment samples by the developed method and compared with standard inductively coupled plasma mass spectrometry (ICP-MS) values. (orig.)

Developing a rapid method for the determination of uranium in pure phosphoric acid and D2 EHPA

International Nuclear Information System (INIS)

Koudsi, Y.; Stas, J.; Al-Merey, R.; shaddoud, G.

1996-02-01

Arsenazo (III) used in titrate uranium spectrophotometrically in phosphoric acid after its extraction into organic phase. In this work we used arsenazo(III) to complex uranyl ion in pure phosphoric acid and in the aqueous phase. The spectrum of the complex shows that λ max is at 650 nm. The linearity of the method is corelated with acid molarity, it is (1 -4, 10 - 30, 10 - 40) ppm uranium for (0.2, 1, 2) M of phosphoric acid respectively. Uranium in D 2 EHPA stripped by phosphoric acid and then determined by this method. Also it has been applied to determine uranium in pure perchloric acid. The method is direct, rapid, very cheap and relatively accurate. (author)

Silver nanoparticles embedded polymer sorbent for preconcentration of uranium from bio-aggressive aqueous media

International Nuclear Information System (INIS)

Das, Sadananda; Pandey, Ashok K.; Athawale, Anjali A.; Subramanian, M.; Seshagiri, T.K.; Khanna, Pawan K.; Manchanda, Vijay K.

2011-01-01

Adsorptive sorbent for bio-aggressive natural aqueous media like seawater was developed by one pot simultaneous synthesis of silver nanoparticles (Ag nps) and poly(ethylene glycol methacrylate phosphate) (PEGMP) by UV-initiator induced photo-polymerization. The photo-polymerization was carried out by irradiating N,N'-dimethylformamide (DMF) solution containing appropriate amounts of the functional monomer (ethylene glycol methacrylate phosphate), UV initiator (α,α'-dimethoxy-α-phenyl acetophenone), and Ag + ions with 365 nm UV light in a multilamps photoreactor. To increase mechanical strength, nano-composite sorbent (Ag-PEGMP) was also reinforced with thermally bonded non-woven poly(propylene) fibrous sheet. Transmission electron microscopy (TEM) of the nano-composite sorbent showed uniform distribution of spherical Ag nanoparticles with particles size ranging from 3 to 6 nm. The maximum amount of Ag 0 that could be anchored in the form of nanoparticles were 5 ± 1 and 10 ± 1 wt.% in self-supported PEGMP and poly(propylene) reinforced PEGMP matrices, respectively. Ag-PEGMP sorbent was found to be stable under ambient conditions for a period of six months. Ag-PEGMP composite sorbent did not exhibit growth at all after incubation with pre-grown Escherichia coli cells, and showed non-adherence of this bacteria to the composite. This indicated that composite sorbent has the bio-resistivity due to bacterial repulsion and bactericidal properties of Ag nanoparticles embedded in the PEGMP. Sorption of U(VI) in PEGMP and Ag-PEGMP nano-composite sorbents from well-stirred seawater was studied to explore the possibility of using it for uranium preconcentration from bio-aggressive aqueous streams. The nano-composite sorbent was used to preconcentrate U(VI) from a process aqueous waste stream.

Preconcentration of uranium in water samples using dispersive liquid-liquid micro- extraction coupled with solid-phase extraction and determination with inductively coupled plasma-optical emission spectrometry

Directory of Open Access Journals (Sweden)

M. Rezaee,

2015-10-01

Full Text Available A new liquid phase microextraction method based on the dispersion of an extraction solvent into aqueous phase coupled with solid-phase extraction was investigated for the extraction, preconcentration and determination of uranium in water samples. 1-(2-Pyridylazo-2-naphthol reagent (PAN at pH 6.0 was used as a chelating agent prior to extraction. After concentration and purification of the samples in SPE C18 sorbent, 1.5 mL elution sample containing 40.0 µL chlorobenzene was injected into the 5.0 mL pure water. After extraction and centrifuging, the sedimented phase was evaporated and the residue was dissolved in nitric acid (0.5 M and was injected by injection valve into the ICP-OES. Some important extraction parameters, such as sample solution flow rate, sample pH, type and volume of extraction and disperser solvents as well as the salt addition were studied and optimized. Under the optimum conditions, the calibration graph was linear in the range of 0.5-500 µg L-1. The detection limit was 0.1 µg L-1. The relative standard deviation (RSD at 5.0 µg L-1 concentration level was 6.6%. Finally, the developed method was successfully applied to the extraction and determination of uranium in the well, river, mineral, waste and tap water samples and satisfactory results were obtained.DOI: http://dx.doi.org/10.4314/bcse.v29i3.4

Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.

Science.gov (United States)

Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

2013-12-15

A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Preconcentration of trace elements from high-purity thorium and uranium on Chelex-100 and determination by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

International Nuclear Information System (INIS)

Raje, Naina; Kayasth, Satish; Asari, T.P.S.; Gangadharan, S.

1994-01-01

Preconcentration of trace impurities from large-sized samples of uranium metal and thorium oxide using a small column of Chelex-100 followed by their determination using graphite furnace atomic absorption spectrometry (GFAAS) is reported. A 0.5-10-g amount of the sample (uranium metal or thorium oxide) was dissolved, complexed with ammonium carbonate and subjected to the ion-exchange procedure. The retained analytes were eluted with 2-4 M nitric acid and brought to a small volume for a final dilution to 10-25 ml for their determination using GFAAS. The validity of the separation procedure and recoveries at μg kg -1 levels was checked by standard addition; the recoveries were >95%

South African uranium industry plans for expansion

International Nuclear Information System (INIS)

James, H.E.; Boydell, D.W.; Simonsen, H.A.

1978-01-01

Resources and production of uranium in South Africa are discussed. The cost of mining and extraction from gold ores is considered. An outline is presented of the extraction and recovery of uranium and of new developments in sorting, milling, and preconcentration. (U.K.)

Metal Recovery and Preconcentration by Edta and Dtpa Modified Silica Surfaces

Directory of Open Access Journals (Sweden)

Eveliina Repo

2017-03-01

Full Text Available This study focuses on the adsorption and preconcentration of various metals by silica gel surfaces modified with aminopolycarboxylic acids namely ethylenediaminetetraacetic acid or diethylenetriamine-pentaacetic acid. The adsorption performance of the studied materials was determined in mixed metal solutions and the adsorption isotherm studies were conducted for cobalt, nickel, cadmium, and lead. The results were modeled using various theoretical isotherm equations, which suggested that two different adsorption sites were involved in metal removal although lead showed clearly different adsorption behavior attributed to its lowest hydration tendency. Efficient regeneration of the adsorbents and preconcentration of metals was conducted with nitric acid. Results indicated that the metals under study could be analyzed rather accurately after preconcentration from both pure, saline and ground water samples.

Study of the dry processing of uranium ores; Etude des traitements de minerais d'uranium par voie seche

Energy Technology Data Exchange (ETDEWEB)

Guillet, H

1959-02-01

A description is given of direct fluorination of pre-concentrated uranium ores in order to obtain the hexafluoride. After normal sulfuric acid treatment of the ore to eliminate silica, the uranium is precipitated by a load of lime to obtain: either impure calcium uranate of medium grade, or containing around 10% of uranium. This concentrate is dried in an inert atmosphere and then treated with a current of elementary fluorine. The uranium hexafluoride formed is condensed at the outlet of the reaction vessel and may be used either for reduction to tetrafluoride and the subsequent manufacture of uranium metal or as the initial product in a diffusion plant. (author) [French] Il s'agit d'une description de fluoration directe de preconcentres de minerais d'uranium en vue d'obtention d'hexafluorure. Apres attaque sulfurique normale du minerai, afin d' eliminer la silice, l' uranium est precipite par un toit de chaux pour obtenir: ou uranate de chaux impur de titre moyen, ou uranium de la dizaine du pourcentage. Ce concentre seche en atmosphere inerte est soumis a un courant de fluor elementaire. L'hexafluorure d'uranium forme est condense a la sortie du reacteur et peut etre utilise soit apres reduction en tetrafluorure par l'elaboration d'uranium metal, soit comme produit de base dans le cadre d'une usine de diffusion. (auteur)

Carbon Paste Electrode Modified with Carbamoylphosphonic Acid Functionalized Mesoporous Silica: A New Mercury-Free Sensor for Uranium Detection

International Nuclear Information System (INIS)

Yantasee, Wassana; Lin, Yuehe; Fryxell, Glen E.; Wang, Zheming

2004-01-01

This study reports a new approach for developing a uranium (U(VI)) electrochemical sensor that is mercury-free, solid-state, and has less chance for ligand depletion than existing sensors. A carbon-paste electrode modified with carbamoylphosphonic acid self-assembled monolayer on mesoporous silica was developed for uranium detection based on an adsorptive square-wave stripping voltammetry technique. Voltammetric responses for U(VI) detection are reported as a function of pH, preconcentration time, and aqueous phase U(VI) concentration. The uranium detection limit is 25 ppb after 5 minutes preconcentration and improved to 1 ppb after 20 minutes preconcentration. The relative standard deviations are normally less than 5%

REE characteristics and uranium metallogenesis of sandstone-type uranium deposits in northern Sichuan

International Nuclear Information System (INIS)

Zhu Xiyang; Wang Yunliang; Wang Zhichang; Zhang Chengjiang

2004-01-01

On the basis of the analysis of a large number of samples at sandstone-type uranium deposits in northern Sichuan, this paper analyses the REE composition of country rocks, ores, calcite-veins and uranium minerals, and systematically summarizes their REE geochemical characteristics, and discusses variation regularity of REE during depositional and diagenetic processes. By comparing these characteristics with those of typical hydrothermal volcanics-type and metamorphic rock type uranium deposits both at home and abroad, authors suggest that sandstone-type uranium deposits in northern Sichuan are characterized by REE geochemical features of hydrothermal reworking metallogenesis, the uranium mineralization has experienced two stages: the diagenetic preconcentration and the concentration of hydrothermal reworking

Study of the dry processing of uranium ores; Etude des traitements de minerais d'uranium par voie seche

Energy Technology Data Exchange (ETDEWEB)

Guillet, H

1959-02-01

A description is given of direct fluorination of pre-concentrated uranium ores in order to obtain the hexafluoride. After normal sulfuric acid treatment of the ore to eliminate silica, the uranium is precipitated by a load of lime to obtain: either impure calcium uranate of medium grade, or containing around 10% of uranium. This concentrate is dried in an inert atmosphere and then treated with a current of elementary fluorine. The uranium hexafluoride formed is condensed at the outlet of the reaction vessel and may be used either for reduction to tetrafluoride and the subsequent manufacture of uranium metal or as the initial product in a diffusion plant. (author) [French] Il s'agit d'une description de fluoration directe de preconcentres de minerais d'uranium en vue d'obtention d'hexafluorure. Apres attaque sulfurique normale du minerai, afin d' eliminer la silice, l' uranium est precipite par un toit de chaux pour obtenir: ou uranate de chaux impur de titre moyen, ou uranium de la dizaine du pourcentage. Ce concentre seche en atmosphere inerte est soumis a un courant de fluor elementaire. L'hexafluorure d'uranium forme est condense a la sortie du reacteur et peut etre utilise soit apres reduction en tetrafluorure par l'elaboration d'uranium metal, soit comme produit de base dans le cadre d'une usine de diffusion. (auteur)

Sorption and preconcentration of uranium and thorium from aqueous solutions using multi-walled carbon nanotubes decorated with magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zolfonoun, Ehsan; Yousefi, Seyed Reza [NFCRS, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

2015-07-01

The presented study investigates application of MWCNTs-Fe{sub 3}O{sub 4} nanocomposite as an adsorbent for solid phase extraction and preconcentration of uranium and thorium prior to inductively coupled plasma optical emission spectrometry determination. The magnetic MWCNTs with adsorbed analytes can be easily separated from the aqueous solution by using an external magnet without additional centrifugation or filtration of the sample. Due to the high surface area of MWCNTs, satisfactory concentration factor and extraction recovery can be achieved with only 10 mg nanocomposite in 5 min. The effects of pH, sorbent amount, eluent type, chelating reagent concentration, sample volume and time on the recovery of the analytes were investigated. Under the optimum conditions, the detection limits for U(VI) and Th(IV) were 0.44 and 0.27 μg L{sup -1}, respectively.

Research on geochronology and uranium source of sandstone-hosted uranium ore-formation in major uranium-productive basins, Northern-China

International Nuclear Information System (INIS)

Xia Yuliang; Liu Hanbin; Lin Jinrong; Fan Guang; Hou Yanxian

2004-12-01

A method is developed for correcting uranium content in uranium ore samples by considering the U-Ra equilibrium coefficient, then a U-Pb isochron is drawn up. By performing the above correction ore-formation ages of sandstone-hosted uranium mineralization which may be more realistic have been obtained. The comparative research on U-Pb isotopic ages of detritic zircon in ore-hosting sandstone and zircon in intermediate-acid igneous rocks in corresponding provenance area indicates that the ore-hosting sandstone is originated from the erosion of intermediate-acid igneous rocks and the latters are the material basis for the formation of the uranium-rich sandstone beds. On the basis of the study on U-Pb isotopic system evolution of the provenance rocks and sandstones from ore-hosting series, it is verified that the uranium sources of the sandstone-hosted uranium deposit are: the intermediate-acid igneous rocks with high content of mobile uranium, and the sandstone bodies pre-concentrated uranium. (authors)

Pyrophoric behaviour of uranium hydride and uranium powders

Science.gov (United States)

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

2010-01-01

Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (Oxidation mechanisms are proposed.

Comparison studies adsorption of thorium and uranium on pure clay minerals and local Malaysian soil sediments

International Nuclear Information System (INIS)

Syed, H.S.

1999-01-01

Adsorption studies of thorium and uranium radionuclides on 9 different pure clay minerals and 4 local Malaysian soil sediments were conducted. Solution containing dissolved thorium and uranium at pH 4.90 was prepared from concentrate sludges from a long term storage facility at a local mineral processing plant. The sludges are considered as low level radioactive wastes. The results indicated that the 9 clay minerals adsorbed more uranium than thorium at pH ranges from 3.74 to 5.74. Two local Malaysian soils were observed to adsorb relatively high concentration of both radionuclides at pH 3.79 to 3.91. The adsorption value 23.27 to 27.04 ppm for uranium and 33.1 to 50.18 ppm for thorium indicated that both soil sediments can be considered as potential enhanced barrier material for sites disposing conditioned wastes containing uranium and thorium. (author)

Method for the recovery of uranium from a concentrate using pure phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

Procedure for the recovery of an uranium bearing concentrate and pure phosphoric acid from a wet process phosphoric acid from the treatment fluid with a precipitation means in conjunction with an organic diluent, the thus formed precipitate to separate and from the remaining mixture of phosphoric acid and diluent the phosphoric acid to extract, characterised in that one applies an inorganic fluorine compound. (G.C.)

Preconcentration of trace elements

International Nuclear Information System (INIS)

Zolotov, Yu. A.; Kuz'min, N.M.

1990-01-01

This monograph deals with the theory and practical applications of trace metals preconcentration. It gives general characteristics of the process and describes in detail the methods of preconcentration: solvent extraction, sorption, co-precipitation, volatilization, and others. Special attention is given to preconcentration in combination with subsequent determination methods. The use of preconcentration in analysis of environmental and biological samples, mineral raw materials, high purity substances, and various industrial materials is also considered

Uranium determination using atomic spectrometric techniques: An overview

International Nuclear Information System (INIS)

Santos, Juracir S.; Teixeira, Leonardo S.G.; Santos, Walter N.L. dos; Lemos, Valfredo A.; Godoy, Jose M.; Ferreira, Sergio L.C.

2010-01-01

This review focuses on the determination of uranium using spectroanalytical techniques that are aimed at total determination such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma optical emission spectrometry (ICP-OES); and inductively coupled plasma mass spectrometry (ICP-MS) that also enables the determination of uranium isotopes. The advantages and shortcomings related to interferences, precision, accuracy, sample type and equipment employed in the analysis are taken into account, as well as the complexity and costs (i.e., acquisition, operation and maintenance) associated with each of the techniques. Strategies to improve their performance that employ separation and/or preconcentration steps are considered, with an emphasis given to solid-phase extraction because of its advantages compared to other preconcentration procedures.

Study of the dry processing of uranium ores

International Nuclear Information System (INIS)

Guillet, H.

1959-02-01

A description is given of direct fluorination of pre-concentrated uranium ores in order to obtain the hexafluoride. After normal sulfuric acid treatment of the ore to eliminate silica, the uranium is precipitated by a load of lime to obtain: either impure calcium uranate of medium grade, or containing around 10% of uranium. This concentrate is dried in an inert atmosphere and then treated with a current of elementary fluorine. The uranium hexafluoride formed is condensed at the outlet of the reaction vessel and may be used either for reduction to tetrafluoride and the subsequent manufacture of uranium metal or as the initial product in a diffusion plant. (author) [fr

Preliminary discussion on uranium metallogenic models of China's in-situ leachable sandstone-type uranium deposits

International Nuclear Information System (INIS)

Zhang Jindai; Xu Gaozhong; Chen Anping; Wang Cheng

2005-01-01

By comprehensively analyzing metallogenic environments and main ore-controlling factors of important uranium metallogenic regions of in-situ leachable sandstone-type uranium deposits at the southern margin of Yili basin, at the south-western margin of Turpan-Hami basin and in the northeastern Ordos basin, the authors of this paper discuss the metallogenic models of China's in-situ leachable sandstone-type uranium deposits, and suggest that the interlayer oxidation zone type uranium deposits in Yili and Turpan-Hami basins are basically controlled by favourable structures, sedimentary formations and interlayer oxidation zone, and are characterized by multistage uranium concentration, namely the uranium pre-concentration of ore-hosting sedimentary formation, the uranium ore-formation in the stage of supergenic epigenetic reworking, and the further superimposition enrichment of post-ore tectonic activity. However, the interlayer oxidation zone type uranium deposit in the northeastern Ordos was formed after the formation of the secondary reduction. So, paleo-interlayer oxidation zone type uranium mineralization has the mineralization size much greater than the former two. (authors)

Method to manufacture a nuclear fuel from uranium-plutonium monocarbide or uranium-plutonium mononitride

International Nuclear Information System (INIS)

Krauth, A.; Mueller, N.

1977-01-01

Pure uranium carbide or nitride is converted with plutonium oxide and carbon (all in powder form) to uranium-plutonium monocarbide or mononitride by cold pressing and sintering at about 1600 0 C. Pure uranium carbide or uranium nitride powder is firstly prepared without extensive safety measures. The pure uranium carbide or nitride powder can also be inactivated by using chemical substances (e.g. stearic acid) and be handled in air. The sinterable uranium carbide or nitride powder (or also granulate) is then introduced into the plutonium line and mixed with a nonstoichiometrically adjusted, prereacted mixture of plutonium oxide and carbon, pressed to pellets and reaction sintered. The surface of the uranium-plutonium carbide (higher metal content) can be nitrated towards the end of the sinter process in a stream of nitrogen. The protective layer stabilizes the carbide against the water and oxygen content in air. (IHOE) [de

β → α isothermal transformation in pure and weakly alloyed uranium

International Nuclear Information System (INIS)

Aubert, H.; Lelong, C.

1966-01-01

The TTT diagrams describing the β → α isothermal transformation have been made by isothermal dilatometry for pure uranium and 21 alloys based on chromium, silicon, molybdenum, iron, aluminium, zirconium. The thermal cycle preceding the isothermal step influences the decomposition kinetics at temperature corresponding to the eutectoid and martensitic mechanisms, but not in the range where the bainitic transformation occurs. The stability of the β phase decreases with the chromium, molybdenum and silicon concentration: it is affected differently for each of the three transformation mechanisms. The ternary additions, even at very low concentration have a considerable effect on the stability. When the concentration decreases the martensitic mechanism is active at progressively higher temperature, diminishing to the point of disappearance the temperature range where the transformation is considered as being of the bainitic mode. (author) [fr

preconcentration of uranium in water samples using dispersive

African Journals Online (AJOL)

B. S. Chandravanshi

Atomic Energy Organization of Iran, P.O. Box 14395-836, Tehran, Iran. 2Department of ... A new liquid phase microextraction method based on the dispersion of an extraction solvent into aqueous phase ... optical emission spectrometry, Uranium, Water samples ..... The validation of the presented procedure was performed ...

50 years of uranium metal production in Uranium Metal Plant, BARC, Trombay

International Nuclear Information System (INIS)

2009-01-01

The Atomic Energy Programme in India, from the very beginning, has laid emphasis on indigenous capabilities in all aspects of nuclear technology. This meant keeping pace with developments abroad and recognizing the potentials of indigenous technologies. With the development of nuclear programme in India, the importance of uranium was growing at a rapid pace. The production of reactor grade uranium in India started in January 1959 when the first ingot of nuclear pure uranium was discharged using CTR process at Trombay. The decision to set up a uranium refinery to purify the crude uranium fluoride, obtained as a by-product of the DAE's Thorium Plant at Trombay, and to produce nuclear grade pure uranium metal was taken at the end of 1956. The task was assigned to the 'Project Fire Wood Group'. The main objective of the plant was to produce pure uranium metal for use in the Canada India Reactor and Zerlina. Besides this, it was to function as a pilot plant to collect operational data and to train personnel for larger plants to be set up in future. The plant designing and erection work was entrusted to Messrs. Indian Rare Earths Ltd.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples.

Science.gov (United States)

Khamirchi, Ramzanali; Hosseini-Bandegharaei, Ahmad; Alahabadi, Ahmad; Sivamani, Selvaraju; Rahmani-Sani, Abolfazl; Shahryari, Taher; Anastopoulos, Ioannis; Miri, Mohammad; Tran, Hai Nguyen

2018-04-15

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10 -3 g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10 -3 g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO 3 solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14μg/L, and the relative standard deviation was approximately 3.3% (n = 7). Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Equations of state for enriched uranium and uranium alloy to 3500 MPa

International Nuclear Information System (INIS)

Bai Chaomao; Hai Yuying; Liu Jenlong; Li Zhenrong

1990-04-01

The volume compressions of 6 kinds of cast materials including enriched uranium, poor uranium, U-0.57 wt% Ti, U-0.33 wt% Nb, U-2.85 wt% Nb and U-7.5 wt% Nb-3.3 wt% Zr have been determined by monitoring piston displacements in a piston cylinder apparatus with double strengthening rings to 3500 MPa at room temperature. The dilation of the cylinder vessel and the press deformation were corrected by some experiments. The calculational data free from using the standard sample closed with used standard sample. The volume compressions of enriched uranium and poor uranium are nearly coincident. Pure uranium is more compressible than uranium alloys. These values of enriched uranium are in close agreement with values of Bridgman's pure uranium. The fitting coefficients of Bridgman's polynomial and Anderson's equation of state and isothermal bulk modules for the above materials are given

Electrolytic preconcentration in instrumental analysis.

Science.gov (United States)

Sioda, R E; Batley, G E; Lund, W; Wang, J; Leach, S C

1986-05-01

The use of electrolytic deposition as a separation and preconcentration step in trace metal analysis is reviewed. Both the principles and applications of the technique are dealt with in some detail. Electrolytic preconcentration can be combined with a variety of instrumental techniques. Special attention is given to stripping voltammetry, potentiometric stripping analysis, different combinations with atomic-absorption spectrometry, and the use of flow-through porous electrodes. It is pointed out that the electrolytic preconcentration technique deserves more extensive use as well as fundamental investigation.

Flotation of uranium from uranium ores in Canada. Part 1

International Nuclear Information System (INIS)

Muthuswami, S.V.; Vigayan, S.; Woods, D.R.; Banerjee, S.

1983-01-01

About 150 flotation tests were done on Elliot Lake ore with 15 reagents as collectors in order to screen and choose an attractive collector for uranium flotation. Several variables were studied including pH, conditioning time and mode of collector addition. The tests were done in a Denver or Agitair subaeration cell. The particle size of the ore was kept at 85% below -325 mesh. Three reagents (Kelex 00, TOPO, and cupferron) were identified as having the most promise. The best results were obtained with cupferron, where 93-95% of the uranium was recovered in 25-30% of the mass of original ore. Radium in the tails varied between 5 and 30 pCi/g depending on the mass of uranium floated. Radium was recovered in proportion to uranium in the tests done at neutral pH. The preconcentration results obtained by flotation alone were comparable to those obtained using pyrite flotation and wet high-intensity magnetic separation of uranium. The consumption of cupferron was 4 kg/Mg ore for each flotation stage. This was 10-15 times larger than the collector usage in conventional oxide flotation. This scheme did not require other reagents as depressants, activators or modifiers. Reproducibility was good and similar recoveries were obtained with fresh or old ores, and with distilled or mine water. The selectivity of cupferron for uranium in the ore studied was outstanding

Biological preconcentrator

Science.gov (United States)

Manginell, Ronald P [Albuquerque, NM; Bunker, Bruce C [Albuquerque, NM; Huber, Dale L [Albuquerque, NM

2008-09-09

A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

Preserving Ultra-Pure Uranium-233

International Nuclear Information System (INIS)

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

2011-01-01

Uranium-233 ( 233 U) is a synthetic isotope of uranium formed under reactor conditions during neutron capture by natural thorium ( 232 Th). At high purities, this synthetic isotope serves as a crucial reference material for accurately quantifying and characterizing uranium-bearing materials assays and isotopic distributions for domestic and international nuclear safeguards. Separated, high purity 233 U is stored in vaults at Oak Ridge National Laboratory (ORNL). These materials represent a broad spectrum of 233 U from the standpoint of isotopic purity - the purest being crucial for precise analyses in safeguarding uranium. All 233 U at ORNL is currently scheduled to be disposed of by down-blending with depleted uranium beginning in 2015. This will reduce safety concerns and security costs associated with storage. Down-blending this material will permanently destroy its potential value as a certified reference material for use in uranium analyses. Furthermore, no credible options exist for replacing 233 U due to the lack of operating production capability and the high cost of restarting currently shut down capabilities. A study was commissioned to determine the need for preserving high-purity 233 U. This study looked at the current supply and the historical and continuing domestic need for this crucial isotope. It examined the gap in supplies and uses to meet domestic needs and extrapolated them in the context of international safeguards and security activities - superimposed on the recognition that existing supplies are being depleted while candidate replacement material is being prepared for disposal. This study found that the total worldwide need by this projection is at least 850 g of certified 233 U reference material over the next 50 years. This amount also includes a strategic reserve. To meet this need, 18 individual items totaling 959 g of 233 U were identified as candidates for establishing a lasting supply of certified reference materials (CRM), all

Standardization of solvent extraction procedure for determination of uranium in seawater

International Nuclear Information System (INIS)

Sukanta Maity; Sahu, S.K.; Pandit, G.G.

2015-01-01

Solvent extraction procedure using ammonium pyrolidine dithiocarbamate complexing agent in methyl isobutyl ketone organic phase and acid exchange back-extraction is described for the simultaneous quantitative pre-concentration of uranium in seawater followed by its determination by differential pulse adsorptive stripping voltammetry. Solvent extraction time is optimized for extraction of uranium from seawater. Solvent extraction efficiency for uranium in seawater at different pH was carried out. The method gives a recovery of 98 ± 2 % for 400 mL sample at pH 3.0 ± 0.02, facilitating the rapid and interference free analysis of seawater samples. (author)

Study on geochronology and uranium source of sandstone-type uranium deposit in Dongsheng area

International Nuclear Information System (INIS)

Liu Haibin; Xia Yuliang; Tian Shifeng

2007-01-01

This paper studied the geochronology of sandstone-type uranium deposit in the Dongsheng area of Ordos Basin. In eastern segment, ages of mineralization at the wing of the ore-roll are found to be 120 ± 5 Ma and 80 ± 5 Ma, and at the front of the ore-roll are 20 ± 2 Ma and 8 ± 1 Ma; While in middle segment, ages of mineralization are 124 ± 6 Ma and 80 ± 5 Ma. This means that the main mineralization in Dongsheng area were formed at early Jurassic and late Cretaceous, and correspondent to the time of structure uplift. Mineralization of roll-front (rich ore) which formed in Miocene and Pliocene may related to tectonic-thermal event taken place at that time and reformed the early mineralization in this area. The isochron line age of sample with uranium grade 0 ) in the sandbody is 24.64 x 10 -6 also shows the uranium pre-concentration in the strata. The even value of ΔU of rocks in Zhiluo formation is -70.2%, this shows that non-mineralized rocks have migrated uranium and acted as important metallogenic uranium sources. (authors)

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)

REE geochemistry and genesis of Daxin uranium deposit

International Nuclear Information System (INIS)

Li Zhixing; Qi Fucheng; He Zhongbo; Zhang Zilong

2011-01-01

Through the analysis on typical REE parameters,chondrite-normalized REE patterns and hierarchical cluster analysis of rocks in the structural-geochemical zonation in Daxin uranium deposit, the paper discusses the uranium source and genesis. The study shows that the uranium source mainly came from Cambrian System. The Devonian System is maily as the favorable room for saving ores in addition to pre-concentrated room for uranium. Underground water resulted from early and late Yanshanian movement and the heating of volcanic rock was turned into geothermal water and it was moved upward by the force of tectonic movement. The geothermal water mainly extracted active uranium from the Cambrian rocks, then moved upward along main regional fault (F2) connecting the Cambrian rocks and the Devonian rocks until it arrived in structural fracture zone which was controlled by secondary faults (F13, F23, F33). At last, the uranium element in geothermal water was precipitated and concentrated into the uranium deposit in reducing environment of enriched organic material and pyrite. (authors)

A Novel Method for the Filterless Preconcentration of Iron

DEFF Research Database (Denmark)

Andersen, Jens Enevold Thaulov

2005-01-01

A novel method of analysis of iron by filterless preconcentration is presented. This is the first example of efficient preconcentration of a refractory transition metal where coprecipitation and columns were omitted. The method applies a manifold of flow injection analysis (FIA) to iron species...... that are preconcentrated on the inner walls of a tubular reactor. It was found that the adsorption of iron species to the walls was particularly pronounced in reactors of nylon material and enrichment factors of 30-35 could be attained, as dependent on the length of the reactor and on the time of preconcentration....... In the preconcentration step of the FIA accessory, the optimum efficacy was obtained when the acidity of the samples were adjusted by HCl to pH = 2.5 whereas the ammonia preconcentration buffer should be kept alkaline at pH = 9.8. After being preconcentrated on the tubular reactor, the iron species were eluted...

The impact of new technology on the economics of uranium production from low-grade ores

International Nuclear Information System (INIS)

Simonsen, H.A.; Boydell, D.W.; James, H.E.

1981-01-01

The subject is discussed under the following headings: influence of a depressed market on uranium supply from low-grade ores; potential areas for a reduction in uranium ore processing costs; in-situ leaching (solution mining; heap leaching; resin-in-pulp; solvent-in-pulp; belt filtration; continuous ion exchange; solvent extraction); preconcentration (upgrading of coarse rock; upgrading in the mill; wet high-intensity magnetic separation; flotation); summary and conclusions. (U.K.)

High-throughput liquid-absorption preconcentrator sampling methods

Science.gov (United States)

Zaromb, Solomon

1994-01-01

A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis.

Thin film-XRF determination of uranium following thin-film solid phase extraction

Energy Technology Data Exchange (ETDEWEB)

Hassan, Jalal, E-mail: jalalhassan@ut.ac.ir [Department of Toxicology, Faculty of Veterinary Medicine, University of Tehran (Iran, Islamic Republic of); Hosseini, Seyed M.; Mozaffari, Shahla [Department of Chemistry, Payame Noor University, Tehran (Iran, Islamic Republic of); Jahanparast, Babak; Karbasi, Mohammad H. [Iranian Mineral Processing Research Center, Ministry of Industry and Mineral, Karaj (Iran, Islamic Republic of)

2014-07-01

A sensitive method based on the preconcentration of uranium on modified filter paper (thin film) has been developed to determinate this element in water and soil samples by wavelength dispersive X-ray fluorescence. Uranium (VI) extraction from nitric acid medium by trioctyl phosphine (TOPO) from 100 mL of sample was carried out. The effects of nitric acid concentration, TOPO concentration and sample breakthrough on uranium extraction were investigated in this study. The proposed method provided good linearity from 7 to 1000 μg and the limit of detection (LOD), based on a signal-to noise ratio (S/N) of 3, was 2.5 μg. (author)

Synthesis of novel chitosan resin derivatized with serine moiety for the column collection/concentration of uranium and the determination of uranium by ICP-MS

International Nuclear Information System (INIS)

Oshita, Koji; Oshima, Mitsuko; Gao Yunhua; Lee, Kyue-Hyung; Motomizu, Shoji

2003-01-01

A chitosan resin derivatized with serine moiety (serine-type chitosan) was newly developed by using the cross-linked chitosan as a base material. The adsorption behavior of trace amounts of metal ions on the serine-type chitosan resin was systematically examined by packing it in a mini-column, passing a metal solution through it and measuring metal ions in the effluent by ICP-MS. The resin could adsorb a number of metal cations at pH from neutral to alkaline region, and several oxoanionic metals at acidic pH region by an anion exchange mechanism. Uranium and Cu could be adsorbed selectively at pH from acidic to alkaline region by a chelating mechanism; U could be adsorbed quantitatively even at pH 3-4. Uranium adsorbed on the resin was easily eluted with 1 M nitric acid: the preconcentration (5-, 10-, 50- and 100-fold) of U was possible. The column treatment method was used prior to the ICP-MS measurement of U in natural river, sea and tap waters; R.S.D. were 2.63, 1.13 and 1.37%, respectively. Uranium in tap water could be determined by 10-fold preconcentration: analytical result was 1.46±0.02 ppt. The resin also was applied to the recovery of U in sea water: the recovery tests for artificial and natural sea water were 97.1 and 93.0%, respectively

Radiation damage of metal uranium

International Nuclear Information System (INIS)

Mihajlovic, A.

1965-01-01

This report is concerned with the role of dispersion second phase in uranium and burnup rate. The role of dispersion phases in radiation stability of metal uranium was studies by three methods: variation of electric conductivity dependent on the neutron flux and temperature of pure uranium for different states of dispersion second phase; influence of dispersion phase on the radiation creep; transmission electron microscopy of fresh and irradiated uranium

Microfluidic paper-based biomolecule preconcentrator based on ion concentration polarization.

Science.gov (United States)

Han, Sung Il; Hwang, Kyo Seon; Kwak, Rhokyun; Lee, Jeong Hoon

2016-06-21

Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization (ICP) with minimal addition on lateral-flow paper. The cation selective membrane (i.e., Nafion) is patterned on adhesive tape, and this tape is then attached to paper-based channels. When an electric field is applied across the Nafion, ICP is initiated to preconcentrate the biomolecules in the paper channel. Departing from previous paper-based preconcentrators, we maintain steady lateral fluid flow with the separated Nafion layer; as a result, fluorescent dyes and proteins (FITC-albumin and bovine serum albumin) are continuously delivered to the preconcentration zone, achieving high preconcentration performance up to 1000-fold. In addition, we demonstrate that the Nafion-patterned tape can be integrated with various geometries (multiplexed preconcentrator) and platforms (string and polymer microfluidic channel). This work would facilitate integration of various ICP devices, including preconcentrators, pH/concentration modulators, and micro mixers, with steady lateral flows in paper-based platforms.

Uranium and thorium concentration process during partial fusion and crystallization of granitic magma

International Nuclear Information System (INIS)

Cuney, M.

1982-01-01

Two major processes, frequently difficult to distinguish, lead to uranium and thorium enrichment in igneous rocks and more particularly in granitoids; these are partial melting and fractional crystallization. Mont-Laurier uranothoriferous pegmatoids, Bancroft and Roessing deposits are examples of radioelement concentrations resulting mostly of low grade of melting on essentially metasedimentary formations deposited on a continental margin or intracratonic. Fractional crystallization follows generally partial melting even in migmatitic areas. Conditions prevailing during magma crystallization and in particular oxygen fugacity led either to the formation of uranium preconcentrations in granitoids, or to its partition in the fluid phase expelled from the magma. No important economic uranium deposit appears to be mostly related to fractional crystallization of large plutonic bodies

Gravimetric Analysis of Uranium in Yellow Cake

International Nuclear Information System (INIS)

Srinuttrakul, Wannee; Jantha, Suwat

2007-08-01

Full text: The gravimetric analysis of uranium in yellow cake is composed of several stages. The analysis takes a long time, which is the disadvantage of this method. However, this gravimetric method provides accurate result for determining the major content of sample. Uranium is the main composition of yellow cake, while Thorium, rare earths and other elements are minor and trace elements. In this work, anion exchange resin was used to separate uranium from other elements to yield highly pure uranium suitable for precipitation. This pure uranium was burnt to U3O8, a form that is stable enough to be weighed. From the optimal condition, the recovery of U3O8 after separating uranium from rare earths and iron is 99.85 ± 0.21%. The application of anion exchange separation was used to analyze uranium in yellow cake obtained from monazite digestion process. It was found that U3O8 in yellow cake is 78.85 ± 2.03%

Development of a choronocoulometric method for determining traces of uranium using the catalytic nitrate reduction

International Nuclear Information System (INIS)

Cantagallo, M.I.C.; Gutz, I.G.R.

1990-01-01

With the aim of improving the sensitivity of the electroanalytical determination of uranium at trace levels. The uranium catalyzed reduction of nitrate on mercury electrode and the technique of chronocoulometry were used. Several experimental parameters were investigated (electrolyte composition, potential program, integration time, blank correction, temperature, previous separation) and adequate conditions were selected for the analytical determination. Under these conditions it was possible to exceed the best reported sensitivity for the catalytic determination, extending the detection limit to 3.10 -10 M. Exploratory study of the combination of this procedure with pre-concentration of uranium ions on the electrode revealed a detection limit ten limes lower. (author) [pt

Lithogeochemistry on uranium deposit at Rabau Hulu Sector, West Kalimantan

International Nuclear Information System (INIS)

Sodikin, Me; Sustarman, Herwandi; Kaswadi

1995-01-01

Compilation of lithogeochemical patterns of Rabau Hulu uranium mineralization sector was conducted by studying 252 samples data collected from exploration and evaluation drill holes. The patterns were characterized by chemical composition and mineralogical changes as well as trace elements enrichment. By knowing the patterns, alteration and trace elements halos around uranium minerals can be determined. While alteration halos can be identified by examining the ratio of K 2 O/Al 2 O 3 , MgO/Al 2 O 3 and Fe 2 O 3 /MgO in the samples, trace elements halos can be distinguished by the presence of Ni, Co, Cu, Pb, Zn, Mo and V. The Pb and Zn halo identification can be employed as a very effective exploration techniques, respectively. In conclusion, experimental data indicate that the Rabau Hulu sector can be classified into an intensive alteration sector with uranium enrichment in this area. The presence of uranium enrichment outside the kaolinitic zone also suggests preconcentration of uranium through metamorphism. (author). 2 tabs, 8 figs, 4 refs

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.)

Preconcentration of silver as silver xanthate on activated carbon

International Nuclear Information System (INIS)

Ramadevi, P.; Naidu, U.V.; Naidu, G.R.K.

1988-01-01

Silver from aqueous solution was preconcentrated by adsorption on activated carbon as silver xanthate. Factors influencing the adsorption of silver were studied. Optimum conditions for the preconcentration of silver were established. (author) 9 refs.; 3 tabs

Determination of mercury and copper in water samples by activation analysis using preconcentration on emission spectroscopic carbon powder

International Nuclear Information System (INIS)

Nagatsuka, Sumiko; Tanizaki, Yoshiyuki

1978-01-01

A simple preconcentration procedure for mercury and copper was examined in the activation analysis of water samples. The preconcentration using pure activated carbon has been reported in several papers. The authors found that the carbon powder for emission spectroscopic analysis showed the high purity equivalent to pure activated carbon. The influence of various parameters in adsorption conditions was studied by radioactive tracers 197 Hg and 64 Cu. It was confirmed that 100% of these elements were adsorbed on carbon powders as pyrrolidine dithiocarbonate complexes at an acidity of pH 6 - 8, the temperature of 50 0 C and the stirring time of 30 minutes. This method was applied to the activation analysis of the river water samples taken from the upper stream area of the Arakawa river and the ground water samples taken from the wells of the environs of Tokyo Megalopolis. The carbon powders which adsorbed these elements were filtered, dried and analyzed by instrumental neutron activation analysis. The Hg concentrations of 0.01 - 0.1 ppb in river water and 0.03 - 1.4 ppb in ground water were obtained as well as the Cu concentrations of 0.3 - 3.0 ppb in ground water. The limits of determination of this method are 0.01 ppb Hg and 0.2 ppb Cu in the case of 1.1 sample of fresh water. (auth.)

Thermal Analysis of Pure Uranium Metal, UMo and UMoSi Alloys Using a Differential Thermal Analyzer

International Nuclear Information System (INIS)

Yanlinastuti; Sutri Indaryati; Rahmiati

2010-01-01

Thermal analysis of pure uranium metal, U-7%Mo and U-7%Mo-1%Si alloys have been done using a Differential Thermal Analyzer (DTA). The experiments are conducted in order to measure the thermal stability, thermochemical properties of elevated temperature and enthalpy of the specimens. From the analysis results it is showed that uranium metal will transform from α to β phases at temperature of 667.16°C and enthalpy of 2.3034 cal/g and from β to γ phases at temperature of 773.05 °C and enthalpy of 2.8725 cal/g and start melting at temperature of 1125.26 °C and enthalpy of 2.1316 cal/g. The U-7%Mo shows its thermal stability up to temperature of 650 °C and its thermal changes at temperature of 673.75 °C indicated by the formation of an endothermic peak and enthalpy of 0.0257 cal/g. The U-7%Mo-1%Si alloys shows its thermal stability up to temperature of 550 °C and its thermal changes at temperature of 574.18 °C indicated by the formation of an endothermic peak and enthalpy of 0.613 cal/g. From the three specimens it is showed that they have a good thermal stability at temperature up to 550 °C. (author)

Method of producing thermally stable uranium carbonitrides

International Nuclear Information System (INIS)

Ugajin, M.; Takahashi, I.

1975-01-01

A thermally stable uranium carbonitride can be produced by adding tungsten and/or molybdenum in the amount of 0.2 wt percent or more, preferably 0.5 wt percent or more, to a pure uranium carbonitride. (U.S.)

Battery operated preconcentration-assisted lateral flow assay.

Science.gov (United States)

Kim, Cheonjung; Yoo, Yong Kyoung; Han, Sung Il; Lee, Junwoo; Lee, Dohwan; Lee, Kyungjae; Hwang, Kyo Seon; Lee, Kyu Hyoung; Chung, Seok; Lee, Jeong Hoon

2017-07-11

Paper-based analytical devices (e.g. lateral flow assays) are highly advantageous as portable diagnostic systems owing to their low costs and ease of use. Because of their low sensitivity and detection limits for biomolecules, these devices have several limitations in applications for real-field diagnosis. Here, we demonstrate a paper-based preconcentration enhanced lateral flow assay using a commercial β-hCG-based test. Utilizing a simple 9 V battery operation with a low power consumption of approximately 81 μW, we acquire a 25-fold preconcentration factor, demonstrating a clear sensitivity enhancement in the colorimetric lateral flow assay; consequently, clear colors are observed in a rapid kit test line, which cannot be monitored without preconcentration. This device can also facilitate a semi-quantitative platform using the saturation value and/or color intensity in both paper-based colorimetric assays and smartphone-based diagnostics.

A METHOD OF PREPARING URANIUM DIOXIDE

Science.gov (United States)

Scott, F.A.; Mudge, L.K.

1963-12-17

A process of purifying raw, in particular plutonium- and fission- products-containing, uranium dioxide is described. The uranium dioxide is dissolved in a molten chloride mixture containing potassium chloride plus sodium, lithium, magnesium, or lead chloride under anhydrous conditions; an electric current and a chlorinating gas are passed through the mixture whereby pure uranium dioxide is deposited on and at the same time partially redissolved from the cathode. (AEC)

Uranium market cools: how to make a profit on uranium without mining it

International Nuclear Information System (INIS)

Hallam, John.

1989-01-01

An overview of the uranium world market is given. It is shown that the uranium spot price is now around $9.80/lb., while the Australian 'floor price' is almost three times that on the world markets. This situation has forced the Australian Government to move to individually negotiated floor prices, decided on a contract-by-contract basis. Anti-nuclear groups are opposing to dropping the floor price and suggest that Australian producers will find it more profitable to shut down their operations and act purely as a uranium trading company rather than continuing mining

Processing of Sierra Albarrana uranium ores

International Nuclear Information System (INIS)

Gutierrez Jodra, L.; Perez Luina, A.; Perarnau, M.

1960-01-01

Uranium recovery by hydrometallurgy from brannerite, found in Hornachuelos (Cordoba) is described. It has been studied the acid and alkaline leaching and salt roasting, proving as more satisfactory the acid leaching. Besides the uranium solubilization by acid leaching, is described the further process to obtain pure uranyl nitrate. (Author)

Standardization of solvent extraction procedure for determination of uranium in sea water

International Nuclear Information System (INIS)

Maity, Sukanta; Dusane, C.B.; Sahu, S.K.; Pandit, G.G.

2014-01-01

Marine ecosystem is becoming polluted by heavy metals and naturally occurring radionuclides due to rapid industrialization and human activities. Many contaminants such as heavy metals and naturally occurring radionuclides though occur at extremely low concentration in sea water, are accumulated by marine organisms and concentrations in their body tissue can be hundreds of times greater than sea water. As human being consume different marine organisms like biota, can lead potential health problem to human being. Uranium is a naturally occurring radioactive element which is important for nuclear technology. However, mineral resources for uranium are limited. Seawater is a major source of uranium. The total estimated quantity of uranium in seawater is around four and a half billion tones. Thus, the oceans have the potential to become the most eco-friendly and long sustainable resource for uranium. A number of countries in the world are in search of techniques to recover uranium from seawater economically. For this purpose and also for the environmental monitoring, the determination of uranium in seawater is very much important. Seawater contains very high concentrations of salts and its uranium content is very low. Accordingly, the separation and preconcentration of uranium is usually involved in the analytical procedures used for the determination of uranium in seawater. In the present study solvent extraction procedure was adopted for the determination of uranium in sea water collected from different locations across Thane Creek area, Mumbai, India

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.)

An electrodynamic preconcentrator integrated thermoelectric biosensor chip for continuous monitoring of biochemical process

International Nuclear Information System (INIS)

Choi, Yong-Hwan; Kim, Min-gu; Kang, Dong-Hyun; Sim, Jaesam; Kim, Jongbaeg; Kim, Yong-Jun

2012-01-01

This paper proposes an integrated sensor chip for continuous monitoring of a biochemical process. It is composed of a preconcentrator and a thermoelectric biosensor. In the preconcentrator, the concentration of the injected biochemical sample is electrodynamically condensed. Then, in the downstream thermoelectric biosensor, the preconcentrated target molecules react with sequentially injected capture molecules and generate reaction heat. The reaction heat is detected based on the thermoelectric effect, and an integrated split-flow microchannel improves the sensor stability by providing ability to self-compensate thermal noise. These sequential preconcentration and detection processes are performed in completely label-free and continuous conditions and consequently enhance the sensor sensitivity. The performance of the integrated biosensor chip was evaluated at various flow rates and applied voltages. First, in order to verify characteristics of the fabricated preconcentrator, 10 µm -diameter polystyrene (PS) particles were used. The particles were concentrated by applying ac voltage from 0 to 16 V pp at 3 MHz at various flow rates. In the experimental result, approximately 92.8% of concentration efficiency was achieved at a voltage over 16 V pp and at a flow rate below 100 µl h −1 . The downstream thermoelectric biosensor was characterized by measuring reaction heat of biotin–streptavidin interaction. The preconcentrated streptavidin-coated PS particles flow into the reaction chamber and react with titrated biotin. The measured output voltage was 288.2 µV at a flow rate of 100 µl h −1 without preconcentration. However, by using proposed preconcentrator, an output voltage of 812.3 µV was achieved with a 16 V pp -applied preconcentration in the same given sample and flow rate. According to these results, the proposed label-free biomolecular preconcentration and detection technique can be applied in continuous and high-throughput biochemical applications

Membrane extraction in preconcentration of some uranium fission products

International Nuclear Information System (INIS)

Macasek, F.; Rajec, P.; Kopunec, R.; Mikulaj, V.

1984-01-01

Theoretical comparison of the equilibria and kinetics of solvent extraction (SX) and emulsion liquid membrane extraction (MX) was performed using the distribution ratios at the outer inner boundaries of liquid membrane. Enhancement factors, pertraction factor (p) and mulitplication factor (N), were proposed to express efficiency of the MX technique. The extraction of cesium, strontium, cobalt(II), uranium(VI), cerium(III) and technetium(VII) was investigated from this point of view. The most perspective systems are those with chelating agents (e.g. di-2-ethylhexyl-phosporic acid and 8-hydroquinoline), especially at low concentrations (substioichiometric amounts), with which high enhancement factors can be achieved. The results with the ion-exchange systems (bis(1,2-dicarbollyl)-cobalt(III) and quaternary ammonium salts) may be interpreted as indicating some surface barriers which prevent the transport of ions. 20 references, 14 figures, 6 tables

Non-polluting treatment of uranium effluents from the alkaline digestion of an uranium ore containing sulfur

International Nuclear Information System (INIS)

Berger, Bernard.

1978-01-01

New non-polluting process for treating uranium effluents from the alkaline digestion of an uranium ore containing sulphur, which makes it possible (a) to extract and obtain relatively pure uranium and (b) to process the digestion liquor freed from the uranium and containing in an aqueous solution a mixture of alkaline carbonate and/or bicarbonate and sodium sulphate, consisting in the selective extraction of the sodium sulphate present and the recycling of the liquor free of SO 4 = ions, containing in solution the sole carbonates and/or bicarbonates involved, towards the digestion of the ore [fr

Analysis on uranium mineralization-formation condition and prospecting potential in Xidamingshan metallogenic belt

International Nuclear Information System (INIS)

Li Zhixing; Qi Fucheng; He Zhongbo; Zhang Zilong

2012-01-01

There are many different opinions about the source of uranium and metallogenic mechanism in Xidamingshan metallogenic belt. therefore it blocked uranium resources potential evaluation and ore exploration. Through absorb in- formation and investigate Daxin deposit and systematic analysis on samples. It is believed that uranium source mainly came from Cambrian System, a little came from the deep. The Devonian System is favorable room for saving ores in addition to be pre-concentrated room for uranium. Also, there are new cognition about uranium metallogenic mechanism, establish ore-forming series of Xidamingshan metallogenic belt, It is proposed that uranium mineralization have experienced 4 stages; It is cleared that hydrothermal fluid superposition transform type uranium deposit is main genetic type, ancient karst accumulate type is secondary genetic type, the later is formed by leaching the former and then precipitate, enrichment in ancient karst congeries, which is formed nearby faults and with the movement of Xishan structural movement. It is proven that metallogenic potential of Xidamingshan metallogenic belt is good. Tectonic rock controlled by subsidiary fracture nearby regional main fault, which connected with the Cambrian System and the Devonian System, and the deep of the deposit is guideline of mineral prospecting next stage. (authors)

Determination of uranium in industrial and environmental samples. Vol. 4

Energy Technology Data Exchange (ETDEWEB)

El-Sweify, F H; Shehata, M K; Metwally, E M; El-Shazly, E A.A.; El-Naggar, H A [Nuclear Chemistry Department, Hot Laborities Center, Atomic Energy Authority, Cairo (Egypt)

1996-03-01

The phosphate ores used at `Abu zaabal fertilizer and chemical company` for the production of some chemicals and fertilizers contain detectable amounts of uranium. In this study, the content of uranium in samples of different products of fertilizers, gypsum, and phosphate ore were determined using NAA, and gamma ray spectroscopy of the irradiated samples. Another method based on measuring the natural radioactivity of {sup 238} U series for non-irradiated samples using gamma-ray spectroscopy was also used for determine uranium content in the samples. In the NAA method, the content of U(ppm) in the samples was been computed from the photopeak activity of the lines = 106.1, 228.2, and 277.5 KeV of {sup 239} Np induced in the irradiated samples, and the uranium standard simultaneously irradiated. the gamma-ray spectra, and the decay curves are given. In the second method the gamma-ray spectra of the natural radioactivity of the samples and uranium standard were measured. The gamma-transition of energies 295.1, 251.9 KeV for {sup 214} Pb; 609.3, 768.4, 1120.3, 1238.1 KeV for {sup 214} Bi were determined. The uranium {sup 23U} traces in drainage water was also determined spectrophotometrically using arsenazo-III after preconcentration of uranium from the pretreated drainage water in column packed with chelex-100 resin. The recovery was found to be 90 {+-} 5%. 11 figs., 3 tabs.

Radiation damage of metal uranium; Radijaciono ostecenje metalnog urana

Energy Technology Data Exchange (ETDEWEB)

Mihajlovic, A [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1965-11-15

This report is concerned with the role of dispersion second phase in uranium and burnup rate. The role of dispersion phases in radiation stability of metal uranium was studies by three methods: variation of electric conductivity dependent on the neutron flux and temperature of pure uranium for different states of dispersion second phase; influence of dispersion phase on the radiation creep; transmission electron microscopy of fresh and irradiated uranium.

Sample extraction and injection with a microscale preconcentrator.

Energy Technology Data Exchange (ETDEWEB)

Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Chan, Helena Kai Lun

2007-09-01

This report details the development of a microfabricated preconcentrator that functions as a fully integrated chemical extractor-injector for a microscale gas chromatograph (GC). The device enables parts-per-billion detection and quantitative analysis of volatile organic compounds (VOCs) in indoor air with size and power advantages over macro-scale systems. The 44 mm{sup 3} preconcentrator extracts VOCs using highly adsorptive, granular forms of graphitized carbon black and carbon molecular sieves. The micron-sized silicon cavities have integrated heating and temperature sensing allowing low power, yet rapid heating to thermally desorb the collected VOCs (GC injection). The keys to device construction are a new adsorbent-solvent filling technique and solvent-tolerant wafer-level silicon-gold eutectic bonding technology. The product is the first granular adsorbent preconcentrator integrated at the wafer level. Other advantages include exhaustive VOC extraction and injection peak widths an order of magnitude narrower than predecessor prototypes. A mass transfer model, the first for any microscale preconcentrator, is developed to describe both adsorption and desorption behaviors. The physically intuitive model uses implicit and explicit finite differences to numerically solve the required partial differential equations. The model is applied to the adsorption and desorption of decane at various concentrations to extract Langmuir adsorption isotherm parameters from effluent curve measurements where properties are unknown a priori.

Estimation of uranium isotope in urine samples using extraction chromatography resin

International Nuclear Information System (INIS)

Thakur, Smita S.; Yadav, J.R.; Rao, D.D.

2012-01-01

Internal exposure monitoring for alpha emitting radionuclides is carried out by bioassay samples analysis. For occupational radiation workers handling uranium in reprocessing or fuel fabrication facilities, there exists a possibility of internal exposure and urine assay is the preferred method for monitoring such exposure. Estimation of lower concentration of uranium at mBq level by alpha spectrometry requires preconcentration and its separation from large volume of urine sample. For this purpose, urine samples collected from non radiation workers were spiked with 232 U tracer at mBq level to estimate the chemical yield. Uranium in urine sample was pre-concentrated by calcium phosphate coprecipitation and separated by extraction chromatography resin U/TEVA. In this resin extractant was DAAP (Diamylamylphosphonate) supported on inert Amberlite XAD-7 support material. After co-precipitation, precipitate was centrifuged and dissolved in 10 ml of 1M Al(NO 3 ) 3 prepared in 3M HNO 3 . The sample thus prepared was loaded on extraction chromatography resin, pre-conditioned with 10 ml of 3M HNO 3 . Column was washed with 10 ml of 3M HNO 3 . Column was again rinsed with 5 ml of 9M HCl followed by 20 ml of 0.05 M oxalic acid prepared in 5M HCl to remove interference due to Th and Np if present in the sample. Uranium was eluted from U/TEVA column with 15 ml of 0.01M HCl. The eluted uranium fraction was electrodeposited on stainless steel planchet and counted by alpha spectrometry for 360000 sec. Approximate analysis time involved from sample loading to stripping is 2 hours when compared with the time involved of 3.5 hours by conventional ion exchange method. Seven urine samples from non radiation worker were radio chemically analyzed by this technique and the radiochemical yield was found in the range of 69-91 %. Efficacy of this method against conventional anion exchange technique earlier standardized at this laboratory is also being highlighted. Minimum detectable activity

Lime, agent to uranium concentration; La chaux comme agent de concentration de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Mouret, P; Le Bris, J; Kremer, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Gautier, R [Etablissement Kuhlmann, Service d' Etudes et de Pilotages Industriels (France)

1958-07-01

Choice of the process according to health requirements. Description of the process: dissolution of uranium by sulfuric leaching of ores, precipitation of uranium by lime, re-dissolution of the concentrate with nitric ions, purification by T.B.P. finally resulting in pure uranyl nitrate solution containing 400 g/litre. (author)Fren. [French] Les raisons du choix du procede en fonction des imperatifs d'hygiene, sont exposees ainsi que le procede qui consiste en une dissolution de l'uranium des minerais par lixiviation sulfurique, precipitation de l'uranium par la chaux et redissolution du concentre en presence d'ions nitriques, purification par le T.B.P. et obtention d'un concentre final de nitrate d'uranyle pur a 400 g/litre. (auteur)

Improvement of uranium production efficiency to meet China's nuclear power requirements

International Nuclear Information System (INIS)

Zhang, R.

1997-01-01

Recently China put the Qinshan Nuclear Power Plant, with an installed capacity of 300 MW, in the province of Zhejiang and the Daya Bay Nuclear Power Plant, with a total installed capacity of 2 x 900 MW, in commercial operation. China plans a rapid growth in nuclear power from 1995 to 2010. China's uranium production will therefore also enter a new period with nuclear power increasing. In order to meet the demand of nuclear power for uranium special attention has been paid to both technical progress improvement using management with the aim of reducing the cost of uranium production. The application of the trackless mining technique has enhanced the uranium mining productivity significantly. China has produced a radiometric sorter, model 5421-2 for pre-concentrating uranium run-of-mine ore. This effectively increases the uranium content in mill feed and decreases the operating cost of hydrometallurgical treatment. The in situ leach technique after blasting is applied underground in the Lantian Mine, in addition to the surface heap leaching, and has obtained a perfect result. The concentrated acid-curing, and ferric sulphate trickle leaching process, will soon be used in commercial operation for treating uranium ore grading -5 to -7 mm in size. The annual production capability of the Yining Mine will be extended to 100 tonnes U using improving in situ leaching technology. For the purpose of improving the uranium production efficiency much work has been done optimizing the distribution of production centres. China plans to expand its uranium production to meet the uranium requirements of the developing nuclear power plants. (author). 4 tabs

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

The regional metallogenesis and optimum selection of prospecting target for superlarge uranium deposit in metallogenic area of erguna

International Nuclear Information System (INIS)

Luo Yi; Wang Zhengbang; Hou Huiqun; Zhou Dean; Qi Fucheng; Xiao Xiangping

1995-06-01

The study area, an activation zone of the median Massif in Xingmeng geosynclinal area, geologically underwent the multiple tectono-magmatic reworking of granitizations during Shinagan, Caledonia and Hercynian periods and of continental rift volcanism in the Mesozoic-Cenozoic era. It is an important potential area for uranium metallogenesis in volcanic basin in North China. The study identifies that four stages of uranium preconcentration and three phases of hydrothermal superimposed-reworking uranium metallogenesis occurred along with the regional geological elevation process. Studies on the U-Pb isotope and induced fission track of various kinds of basement rocks from the area indicate that the basement composed of crustal source remelting type Caledonian and Hercynian granites is favourable for uranium metallogenesis in volcanic basin, and that the late Jurassic intermediate-acid volcano-rock directly act as the source of uranium and that Cretaceous-Tertiary extension-rift basalt magmatic activation supply an important hydrothermal reworking condition for the uranium metallogenesis in volcanic basin. Based on comparative study on the metallogenetic conditions of typical large-scale volcanic uranium deposits at home and abroad, nine prospecting criteria are summarized, the polygenetic mixing hydrothermal uranium metallogenetic model for penetrable volcano-collapse basin is presented, and the main prospecting targets of uranium deposits are pointed out. (2 figs.)

The behaviour of uranium metal in hydrogen atmospheres

International Nuclear Information System (INIS)

Allen, G.C.; Stevens, J.C.H.

1988-01-01

The reaction between commercial H 2 and uranium metal leads to the formation of UO 2 due to traces of water vapour or oxygen. When extremely pure H 2 is used uranium hydride may be formed but, even with 99.9999% H 2 , uranium dioxide forms preferentially. The present work identifies the presence of UH 3 in the X-ray photoelectron spectrum of a uranium sample which has been exposed to ca. 10 10 L† H 2 at ca. 200 0 C. This spectrum indicates that the hydride possesses a high degree of covalency, since the oxidation state of uranium in UH 3 appears to be ca. 1.4. (author)

Preparation of the pur uranium-metal

International Nuclear Information System (INIS)

Goldschmidt, B.; Vertes, P.

1955-01-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [fr

Comparison of laser fluorimetry, high resolution gamma-ray spectrometry and neutron activation analysis techniques for determination of uranium content in soil samples

International Nuclear Information System (INIS)

Ghods, A.; Asgharizadeh, F.; Salimi, B.; Abbasi, A.

2004-01-01

Much more concern is given nowadays for exposure of the world population to natural radiation especially to uranium since 57% of that exposure is due to radon-222, which is a member of uranium decay series. Most of the methods used for uranium determination is low concentration require either tedious separation and preconcentration or the accessibility to special instrumentation for detection of uranium at this low level. this study compares three techniques and methods for uranium analysis among different soil sample with variable uranium contents. Two of these techniques, neutron activation analysis and high resolution gamma-ray spectrometry , are non-destructive while the other, laser fluorimetry is done via chemical extraction of uranium. Analysis of standard materials is done also to control the quality and accuracy of the work. In spite of having quite variable ranges of detection limit, results obtained by high resolution gamma-ray spectrometry based on the assumption of having secular equilibrium between uranium and its daughters, which causes deviation whenever this condition was missed. For samples with reasonable uranium content, neutron activation analysis would be a rapid and reliable technique, while for low uranium content laser fluorimetry would be the most appropriate and accurate technique

Method of fabricating a uranium-bearing foil

Science.gov (United States)

Gooch, Jackie G [Seymour, TN; DeMint, Amy L [Kingston, TN

2012-04-24

Methods of fabricating a uranium-bearing foil are described. The foil may be substantially pure uranium, or may be a uranium alloy such as a uranium-molybdenum alloy. The method typically includes a series of hot rolling operations on a cast plate material to form a thin sheet. These hot rolling operations are typically performed using a process where each pass reduces the thickness of the plate by a substantially constant percentage. The sheet is typically then annealed and then cooled. The process typically concludes with a series of cold rolling passes where each pass reduces the thickness of the plate by a substantially constant thickness amount to form the foil.

Application of fibrous complexing sorbents for trace elements preconcentration and separation

International Nuclear Information System (INIS)

Zakhartchenko, E.A.; Myasoedova, G.V.

2003-01-01

This article demonstrates the application of the 'filled' fibrous sorbents for preconcentration and separation of platinum metals, as well as heavy metals and radionuclides. The POLYORGS complexing sorbents and ion-exchangers were used as fillers. Dynamic preconcentration conditions should be set for complete sorption of the elements: diameter and mass of the sorbent disk or the column as well as flow rate of the solution. These conditions depend on specific features of materials to be analysed and the requirements of the experimental task or detection method. Extensive alteration of features as well as perfect kinetic properties and high selectivity of the 'filled' sorbents confirm their applicability for trace elements preconcentration and separation in technology and analytical chemistry. (authors)

Non-polluting treatment of alkaline uranium effluents contaning SO42- ions

International Nuclear Information System (INIS)

Berger, Bernard.

1978-01-01

New non-polluting process for treating uranium effluents from the alkaline digestion of an uranium ore containing sulfur, which makes it possible, on the one hand, to extract uranium and SO 4 2- contained in these effluents allowing the recycling of the sole alkaline carbonates and/or bicarbonates involved, towards the digestion of the ore and on the other hand the separation of the mixture uranium and SO 4 2- ions extracted simultaneously to obtain relatively pure uranium in oxide form [fr

A study of precipitation from pure solutions of uranyl nitrate; Etude de la precipitaion de solutions pures de nitrate d'uranyle

Energy Technology Data Exchange (ETDEWEB)

Decrop, J; Holder, J; Sauteron, J [Commissariat a l' Energie Atomique, Usine du Bouchet, Service des Lab. de Recherches et de Controle, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

After its purification by extraction of the uranyl nitrate from the organic solvent, uranium has to be converted into solid form again: uranium trioxide (UO{sub 3}). It can be done either by thermal decomposition of uranyl nitrate or by precipitation of uranium, followed by filtration and calcination. Only the second method has been studied for now at the Bouchet plant. This paper reports the bench-scale and pilot-scale experiments of the studies of the precipitation of pure solutions of uranyl nitrate using ammonia (gaseous or in solution) or ammonium carbonate. These have been carried out at the Bouchet plant. It investigates the chemical aspect (pH, precipitates chemical composition) and the technical aspect of the different ways of precipitation (conditions of precipitation, decantation and filtration of precipitates). (M.P.)

Box-Behnken design in modeling of solid-phase tea waste extraction for the removal of uranium from water samples

Energy Technology Data Exchange (ETDEWEB)

Khajeh, Mostafa; Jahanbin, Elham; Ghaffari-Moghaddam, Mansour; Moghaddam, Zahra Safaei [Zabol Univ. (Iran, Islamic Republic of). Dept. of Chemistry; Bohlooli, Mousa [Zabol Univ. (Iran, Islamic Republic of). Dept. of Biology

2015-07-01

In this study, the solid-phase tea waste procedure was used for separation, preconcentration and determination of uranium from water samples by UV-Vis spectrophotometer. In addition, Box-Behnken experimental design was employed to investigated the influence of six variables including pH, mass of adsorbent, eluent volume, amount of 1-(2-pyridylazo)-2-naphthol (PAN); and sample and eluent flow rates on the extraction of analyte. High determination coefficient (R{sup 2}) of 0.972 and adjusted-R{sup 2} of 0.943 showed the satisfactory adjustment of the polynomial regression model. This method was used for the extraction of uranium from real water samples.

Box-Behnken design in modeling of solid-phase tea waste extraction for the removal of uranium from water samples

International Nuclear Information System (INIS)

Khajeh, Mostafa; Jahanbin, Elham; Ghaffari-Moghaddam, Mansour; Moghaddam, Zahra Safaei; Bohlooli, Mousa

2015-01-01

In this study, the solid-phase tea waste procedure was used for separation, preconcentration and determination of uranium from water samples by UV-Vis spectrophotometer. In addition, Box-Behnken experimental design was employed to investigated the influence of six variables including pH, mass of adsorbent, eluent volume, amount of 1-(2-pyridylazo)-2-naphthol (PAN); and sample and eluent flow rates on the extraction of analyte. High determination coefficient (R 2 ) of 0.972 and adjusted-R 2 of 0.943 showed the satisfactory adjustment of the polynomial regression model. This method was used for the extraction of uranium from real water samples.

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-07-05

This Conversion and Blending Facility (CBF) will have two missions: (1) convert HEU materials into pure HEU oxide and (2) blend the pure HEU oxide with depleted and natural uranium oxide to produce an LWR grade LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. To the extent practical, the chemical and isotopic concentrations of blended LEU product will be held within the specifications required for LWR fuel. Such blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry. Otherwise, blended LEU will be produced as a waste suitable for storage or disposal.

Uranium transport to solid electrodes in pyrochemical reprocessing of nuclear fuel

International Nuclear Information System (INIS)

Tomczuk, Z.; Ackerman, J.P.; Wolson, R.D.; Miller, W.E.

1992-01-01

A unique pyrochemical process developed for the separation of metallic nuclear fuel from fission products by electrotransport through molten LiCl-KCl eutectic salt to solid and liquid metal cathodes. The process allow for recovery and reuse of essentially all of the actinides in spent fuel from the integral fast reactor (IFR) and disposal of wastes in satisfactory forms. Electrotransport is used to minimize reagent consumption and, consequently, waste volume. In particular, electrotransport to solid cathodes is used for recovery of an essentially pure uranium product in the presence of other actinides; removal of pure uranium is used to adjust the electrolyte composition in preparation for recovery of a plutonium-rich mixture with uranium in liquid cadmium cathodes. This paper presents experiments that delineate the behavior of key actinide and rare-earth elements during electrotransport to a solid electrode over a useful range of PuCl 3 /UCl 3 ratios in the electrolyte, a thermodynamic basis for that behavior, and a comparison of the observed behavior with that calculated from a thermodynamic model. This work clearly established that recovery of nearly pure uranium can be a key step in the overall pyrochemical-fuel-processing strategy for the IFR

Modeling of geochemical processes related to uranium mobilization in the groundwater of a uranium mine

International Nuclear Information System (INIS)

Gomez, P.; Garralon, A.; Buil, B.; Turrero, Ma.J.; Sanchez, L.; Cruz, B. de la

2006-01-01

This paper describes the processes leading to uranium distribution in the groundwater of five boreholes near a restored uranium mine (dug in granite), and the environmental impact of restoration work in the discharge area. The groundwater uranium content varied from < 1 μg/L in reduced water far from the area of influence of the uranium ore-containing dyke, to 104 μg/L in a borehole hydraulically connected to the mine. These values, however, fail to reflect a chemical equilibrium between the water and the pure mineral phases. A model for the mobilization of uranium in this groundwater is therefore proposed. This involves the percolation of oxidized waters through the fractured granite, leading to the oxidation of pyrite and arsenopyrite and the precipitation of iron oxyhydroxides. This in turn leads to the dissolution of the primary pitchblende and, subsequently, the release of U(VI) species to the groundwater. These U(VI) species are retained by iron hydroxides. Secondary uranium species are eventually formed as reducing conditions are re-established due to water-rock interactions

Online preconcentration ICP-MS analysis of rare earth elements in seawater

Science.gov (United States)

Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin

2012-01-01

The rare earth elements (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (˜pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix elements and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (Elemental Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline earth cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2σ) of the technique to be estimated at mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.

Purification process of uranium hexafluoride containing traces of plutonium fluoride and/or neptunium fluoride

International Nuclear Information System (INIS)

Aubert, J.; Bethuel, L.; Carles, M.

1983-01-01

In this process impure uranium hexafluoride is contacted with a metallic fluoride chosen in the group containing lead fluoride PbF 2 , uranium fluorides UFsub(4+x) (0 3 at a temperature such as plutonium and/or neptunium are reduced and pure uranium hexafluoride is recovered. Application is made to uranium hexafluoride purification in spent fuel reprocessing [fr

Preparation of the pur uranium-metal; La preparation de l'uranium-metal pur

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, B; Vertes, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [French] Description detaillee des procedes chimiques mis en jeu pour preparer a l'Usine du Bouchet du Commissariat a l'Energie Atomique (Seine-et-Oise) l'uranium metal pur a partir soit de minerais relativement riches, soit de concentres provenant de traitement physique ou chimique de minerais pauvres. Le traitement nitrique des minerais aboutit a la production d'uranate de soude impur. Ce dernier est a son tour dissous dans l'acide nitrique et le nitrate d'uranyle est extrait par du tributyl-phosphate dilue par un solvant inerte. Le nitrate d'uranyle pur reextrait est transforme successivement en peroxyde d'uranium, en oxyde orange puis en oxyde brun qui est transforme en fluorure par l'acide fluorhydrique anhydre. Le fluorure uraneux est reduit en metal par le calcium pur avec un rendement superieur a 99 %. (auteurs)

Filterless preconcentration, flow injection analysis and detection by inductively-coupled plasma mass spectrometry

DEFF Research Database (Denmark)

Andersen, Jens Enevold Thaulov

The influence of interferences in the analysis of elements by inductively-coupled-plasma mass-spectrometry (ICP-MS) may be significantly diminished by utilising a protocol of flow-injection analysis (FIA). The method is based on filterless preconcentration of metallic elements at the walls...... of a knotted reactor that was made of nylon tubings. In the load mode, the preconcentration was accomplished by precipitation of metallic species in alkaline-buffered carriers onto the inner walls of the hydrofilic tube. After a preconcen-tration period of 40-120 seconds using sample volumes of 4-10 m...... of 10-30 were obtained in the analysis of aluminium, of chromium and of iron, which resulted in detection limits (3) down to 20 g/L at a sampling frequency of 50 per hour. The preconcentration protocol improves the selectivity thus allowing direct determination of the elements in saline media. Anionic...

Surface characterization of uranium metal and uranium dioxide using X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Allen, G.C.; Trickle, I.R.; Tucker, P.M.

1981-01-01

X-ray photoelectron spectra of pure uranium metal and stoichiometric uranium dioxide have been obtained using an AEI ES300 spectrometer. Binding energy values for core and valence electrons have been determined using an internally calibrated energy scale and monochromatic Al Kα radiation. Satellite peaks observed accompanying certain principal core ionizations are discussed in relation to the mechanisms by which they arise. Confirmation is obtained that for stoichiometric UOsub(2.00) a single shake-up satellite is observed accompanying the U 4fsub(7/2,5/2) principal core lines, separated by 6.8 eV to higher binding energy. (author)

Evolution of the uranium industry in France

International Nuclear Information System (INIS)

Maget, P.; Vertes, P.

1964-01-01

The main feature in the development of the French uranium industry during the last few years is the completion of the programme, already started in 1958, for the equipment of mining units and treatment plants. It was thus possible by 1961, to reach a production capacity of about 2000 T of metal contained in concentrates, and about 1800 T of metal of nuclear purity. The prospecting and research carried on in France by the Commissariat and by private Industry have brought about not only a satisfactory renewal of the reserves under exploitation but also the development of two new uranium-producing regions: one of the usual type in France, in the crystalline formations to the South-East of the Massif Central, the other in the Permian sedimentary formations in the department of l'Herault. Uraniferous concentrates are produced in two forms: -on the one hand two chemical plants run by a combined Commissariat-private industry firm, the Societe Industrielle des Minerais de l'Ouest, produce magnesium uranates by a conventional process, in the Vendee and at la Crouzille; - on the other hand two Commissariat plants, one managed by the same Society in the Forez, the other run directly by the Commissariat at Gueugnon in the Grury mining district, at present inactive, produce uranyl nitrate: the former from ore extracted in the Forez region, the latter from magnesium uranate pre-concentrates imported from Gabon. Two Commissariat plants convert the concentrates into a product of nuclear purity: - one at le Bouchet, run by the C.E.A., which also deals with development studies, - the other at Malvesi, managed by a Commissariat-private industry combine, the Societe de Raffinage de l'Uranium. This latter has a production capacity about double that of le Bouchet and uses the same manufacturing processes. The bulk of the uranium metal is still produced by calcium reduction, but the le Bouchet plant is already equipped for magnesium reduction and is using this process. Uranium fluoride

Anodic dissolution polarography used for the direct determination of metals in uranium

International Nuclear Information System (INIS)

Bueno, L.A.O.; Abrao, A.

1976-01-01

An electrochemical method of analysis, consisting of pre-concentration and determination of the elements Cd, Pb, Tl, Bi and Cu, present as impurities in uranium salts has been developed. The anodic stripping polarography has been employed using a dropping mercury electrode. The interference of uranium itself in the determination of these elements was eliminated by changing its reduction potential to - 1,0V (with respect to the Ag/AgCl electrode), thus making possible the analysis of the elements that are reduced at more positive potentials. This was achieved by the addition of sufficient amount of K 2 CO 3 to the uranyl chloride solution (in the 4:1 carbonate to uranyl ratio) so as to form the uranyl tricarbonate ([UO 2 (CO 3 ) 3 ] 4- ) complex anion. The supporting electrolyte was the uranyl complex in K 2 CO 3 0,1M. The final concentration of uranium ranged from 2 to 5 g/l. The detection limits for the studied elements varied from 0,08 to 1,27 ppm (μg of the element/gU). This technique has proved to be very convenient since provides sensitivity and precision. The method makes possible the determination of mentioned elements directly in uranium solutions, avoiding any previous chemical separations [pt

Use of dispersive liquid-liquid microextraction for simultaneous preconcentration of samarium, europium, gadolinium and dysprosium

International Nuclear Information System (INIS)

Mallah, M.H.; Atomic Energy Organization of Iran, Tehran; Shemirani, F.; Ghannadi Maragheh, M.

2008-01-01

A new preconcentration method of dispersive liquid-liquid microextraction (DLLME) was developed for simultaneous preconcentration of samarium, europium, gadolinium and dysprosium. DLLME technique was successfully used as a sample preparation method. In this preconcentration method, an appropriate mixture of extraction solvent, disperser solvent was injected rapidly into an aqueous solution containing Sm, Eu, Gd and Dy after complex formation using chelating reagent of the 1-(2-pyridylazo)-2-naphthol (PAN). After phase separation, 0.5 mL of the settled phase containing enriched analytes was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The main factors affected the preconcentration of Sm, Eu, Gd and Dy were extraction and dispersive solvent type and their volume, extraction time, volume of chelating agent (PAN), centrifuge speed and drying temperature of the samples. Under the best operating condition simultaneous preconcentration factors of 80, 100, 103 and 78 were obtained for Sm, Eu, Gd and Dy, respectively. (author)

Preconcentration NAA for simultaneous multielemental determination in water sample

International Nuclear Information System (INIS)

Chatt, A.

1999-01-01

Full text: Environment concerns with water, air, land and their interrelationship viz., human beings, fauna and flora. One of the important environmental compartments is water. Elements present in water might face a whole lot of physico-chemical conditions. This poses challenges to measure their total concentrations as well as different species. Preconcentration of the elements present in water samples is a necessary requisites in water analysis. For multi elements concentration measurements, Neutron Activation Analysis (NAA) is one of the preferred analytical techniques due to its sensitivity and selectivity. In this talk preconcentration NAA for multielemental determination in water sample determination will be discussed

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

Treatment of uranium turning with the controllable oxidizing process

International Nuclear Information System (INIS)

Shen Bingyi; Zhang Yonggang; Zhen Huikuan

1989-02-01

The concept, procedure and safety measures of the controllable oxidizing for uranium turning is described. The feasibility study on technological process has been made. The process provided several advantages such as: simplicity of operation, no pollution environment, safety, high efficiency and low energy consumption. The process can yield nuclear pure uranium dioxide under making no use of a great number of chemical reagent. It may supply raw material for fluoration and provide a simply method of treatment for safe store of uranium turning

Laboratory studies on leaching of low grade uranium ores and treatment of low level liquid waste generated by leaching experiments

International Nuclear Information System (INIS)

Palabrica, O.T.; Antonino, E.J.; Caluag, L.A.; Villamater, D.

1980-07-01

Acid leaching experiments of preconcentrated uranium ore were carried out at a pulp density of 50% solids, using sulfuric acid with sodium chlorate as oxidant. The different leaching parameters considered in this work were temperature, oxidant level and leaching time. In the experimental procedure, the concentration of oxidant and the temperature were varied to determine how they affect the leaching process. Experimental results are illustrated in tabulated form for better interpretation. Uranium analyses were done by fluorimetric and delayed-neutron activation analysis. An anion exchange method using Dowex 1 x 8, 200-400 mesh (Cl - ) was used in treating the low-level liquid waste generated by leaching experiments. The purpose of this treatment was to minimize radioactive contamination in the waste materials and also to recover some of the uranium left in the liquid waste. (author)

A Convenient Method for Estimation of the Isotopic Abundance in Uranium Bearing Samples

International Nuclear Information System (INIS)

AI -Saleh, F.S.; AI-Mukren, Alj.H.; Farouk, M.A.

2008-01-01

A convenient and simple method for estimation of the isotopic abundance in some uranium bearing samples using gamma-ray spectrometry is developed using a hyper pure germanium spectrometer and a standard uranium sample with known isotopic abundance

Sorption of uranium by cellulose derivatives

International Nuclear Information System (INIS)

Muroi, M.; Imai, S.; Hamaguchi, A.

1985-01-01

The sorption behaviour of uranium was investigated by batch and column methods using four cellulose derivatives, two having an amino group and two having an amino group plus a dithiocarboxylate group. All four derivatives showed maximum uranium sorption from pure water in the neutral region or from artificial sea water in the acidic region. In the batch method, quantitative removal of 100 μg of uranium from 50 ml of water at pH 5.0 was achieved by equilibration with 50 mg of any of the four sorbents. The percentage removal under these conditions decreased gradually with increasing concentration of uranium above 100 μg per 50 ml. A similar high percentage removal of uranium was achieved using artificial sea water. In the column method, quantitative removal of 5 μg of uranium from 1l of water at pH 6.7 was achieved with 200 mg of either of the two sorbents. Similar quantitative removal of uranium was achieved from 1l of artificial sea water at pH 5.4 with 500 mg of either of the two sorbents. (author)

Kinetics of the reduction of uranium oxide catalysts

International Nuclear Information System (INIS)

Heynen, H.W.G.; Camp-van Berkel, M.M.; Bann, H.S. van der

1977-01-01

The reduction of uranium oxide and uranium oxide on alumina catalysts by ethylbenzene and by hydrogen has been studied in a thermobalance. Ethylbenzene mole fractions between 0.0026 and 0.052 and hydrogen mole fractions between 0.1 and 0.6 were applied at temperatures of 425--530 0 C. During the reduction the uranium oxides are converted into UO 2 . The rate of reduction of pure uranium oxide appears to be constant in the composition region UO/sub 2.6/-UO/sub 2.25/. The extent of this region is independent of the concentration of the reducing agents and of the reaction temperature. The constant rate is explained in terms of a constant oxygen pressure which is in equilibrium with the two solid phases, U 3 O/sub 8-x/ and U 4 O 9 . The reduction rate is first order in hydrogen and zero order in ethylbenzene with activation energies of 120 and 190 kJ mol -1 , respectively. Oxygen diffusion through the lattice is probably not rate limiting. The reduction behavior of uranium oxide on alumina is different from that of pure uranium oxide; the rate of reduction continuously decreases with increasing degree of reduction. An explanation for this behavior has been given by visualizing this catalyst as a set of isolated uranium oxide crystallites with a relative wide variation of diameters, in an alumina matrix. At the beginning of the reduction, carbon dioxide and water are the only reaction products. Thereafter, benzene is found as well and, finally, at U/O ratios below 2.25, styrene also appears in the reactor outlet

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

International Nuclear Information System (INIS)

1995-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-07-05

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

Sequoyah Uranium Hexafluoride Plant (Docket No. 40-8027): Final environmental statement

International Nuclear Information System (INIS)

1975-02-01

The proposed action is the continuation of Source Material License SUB-1010 issued to Kerr-McGee Nuclear Corporation authorizing the operation of a uranium hexafluoride manufacturing facility located in Sequoyah County, Oklahoma, close to the confluence of the Illinois and Arkansas Rivers. The plant produces high purity uranium hexafluoride using uranium concentrates (yellowcake) as the starting material. It is currently designed to produce 5000 tons of uranium per year as uranium hexafluoride and has been in operation since February 1970 without significant environmental incident or discernible offsite effect. The manufacturing process being used includes wet chemical purification to convert yellowcake to pure uranium trioxide followed by dry chemical reduction, hydrofluorination, and fluorination technique to produce uranium hexafluoride. 8 figs, 12 tabs

Preconcentration of traces of radionuclides and elements with foamed polyurethane sorbents in the analysis of environmental samples

International Nuclear Information System (INIS)

Palagyi, S.; Braun, T.

1986-01-01

The importance of preconcentration and the permanent need of efficient preconcentrating agents in environmental analysis are pointed out. Foamed polyurethane sorbents draw attention as novel agents in separation chemistry. A survey is presented of recent applications of unloaded and reagent-loaded open-cell type resilient polyurethane foams in the separation and preconcentration of radionuclides from environmental samples, and of the latest uses of these foams in the preconcentration and detection of traces of some, mainly inorganic materials in environmental samples, using radioanalytical techniques. Possible future uses of polyurethane foams in trace element detection in environmental analysis are outlined. (author)

A study of precipitation from pure solutions of uranyl nitrate

International Nuclear Information System (INIS)

Decrop, J.; Holder, J.; Sauteron, J.

1961-01-01

After its purification by extraction of the uranyl nitrate from the organic solvent, uranium has to be converted into solid form again: uranium trioxide (UO 3 ). It can be done either by thermal decomposition of uranyl nitrate or by precipitation of uranium, followed by filtration and calcination. Only the second method has been studied for now at the Bouchet plant. This paper reports the bench-scale and pilot-scale experiments of the studies of the precipitation of pure solutions of uranyl nitrate using ammonia (gaseous or in solution) or ammonium carbonate. These have been carried out at the Bouchet plant. It investigates the chemical aspect (pH, precipitates chemical composition) and the technical aspect of the different ways of precipitation (conditions of precipitation, decantation and filtration of precipitates). (M.P.)

Simultaneous determination of actinide and strontium nuclides by extraction chromatography

International Nuclear Information System (INIS)

Vajda, N.; Molnar, Zs.

1999-01-01

A relatively fast and simple separation procedure has been developed for the simultaneous determination of thorium, uranium, neptunium, plutonium, americium, curium and strontium radionuclides. Most of the isotopes of these elements are long-lived, pure alpha and beta emitters regarded as 'difficult to determine' ones in the literature. Our major goal was to develop a combined procedure capable for the analysis of all these nuclides in the same sample aliquot so that correlations can be revealed without the errors arising due to inhomogeneity of samples when the radionuclides are determined from different sub-samples. The combined procedure has the advantage that sample destruction becomes simpler and faster, too. The chemical procedure consists of co-precipitations for the pre-concentration of groups of chemically similar elements and extraction chromatographic separations for the purification of individual elements. By means of pre-concentration relatively big samples can be treated offering the possibility of low activity measurements that cannot be performed by analysing small sample amounts. Pre-concentration techniques were always chosen in order to improve the selectivity of the following separation steps. (authors)

Preparation of the pur uranium-metal; La preparation de l'uranium-metal pur

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, B.; Vertes, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [French] Description detaillee des procedes chimiques mis en jeu pour preparer a l'Usine du Bouchet du Commissariat a l'Energie Atomique (Seine-et-Oise) l'uranium metal pur a partir soit de minerais relativement riches, soit de concentres provenant de traitement physique ou chimique de minerais pauvres. Le traitement nitrique des minerais aboutit a la production d'uranate de soude impur. Ce dernier est a son tour dissous dans l'acide nitrique et le nitrate d'uranyle est extrait par du tributyl-phosphate dilue par un solvant inerte. Le nitrate d'uranyle pur reextrait est transforme successivement en peroxyde d'uranium, en oxyde orange puis en oxyde brun qui est transforme en fluorure par l'acide fluorhydrique anhydre. Le fluorure uraneux est reduit en metal par le calcium pur avec un rendement superieur a 99 %. (auteurs)

The pretreatment of uranium ores by physical processing; Les problemes de la preconcentration des minerais d'uranium par voie physique

Energy Technology Data Exchange (ETDEWEB)

Vuchot, L; Ginocchio, A; Hubert, G; Roques, E; Sandier, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

After giving an outline of the classical means of physical processing - granulometry, gravimetry, flotation, magnetism, electrostatics, the authors study the methods peculiar to radioactive ores: pretreatment in batches (counting cylinders) or stone by stone (electronic sorting belt). The three factors to be considered in any treatment operation are studied (cost of the operation, metal recovery, ratio of concentration), as well as their bearing on the cost and the productivity of the following operations. Making use of radioactivity in order to find out instantaneously the approximate grade of the obtained product makes it possible to reduce costs and improve results by setting up total automation. (author) [French] Apres un apercu des procedes classiques de concentration physique des minerais - granulometrie, gravimetrie, flottation, magnetisme et electrostatique, les auteurs s'attachent aux methodes propres aux minerais radioactifs: preconcentration par lots (cylindre de comptage) ou caillou par caillou (bande de triage electronique). Les trois facteurs a considerer lors de toute operation de traitement sont etudies (prix de revient de l'operation, rendement metal et rendement poids), ainsi que leurs repercussions sur les prix de revient et rendements des traitements ulterieurs. L'utilisation de la radioactivite pour determiner instantanement la teneur approximative des produits obtenus permet d'envisager de reduire les prix de revient et d'ameliorer les resultats par une automatisation totale. (auteur)

Interaction of uranium with Pleurotus sp

International Nuclear Information System (INIS)

Ohnuki, Toshihiko; Sakamoto, Fuminori; Kozaki, Naofumi; Ozaki, Takuro; Samadfam, Mohammad

2002-01-01

Uptake of uranium by higher fungi, such as mushroom is little elucidated. We have studied the interaction of uranium with Pleurotus sp. (a mushroom) in pure culture over a wide range of U concentration (50-3000 mg/L). The Pleurotus sp. was cultured in two different media. One was rice bran medium, and the other was agar (yeast extract, peptone and dextrose) medium. The uptake of uranium in Pleurotus sp. was examined by alpha ray autoradiography (A,A), X-ray fluorescence spectroscopy (XRF) and scanning microcopy (SEM) equipped with EDS. In the agar medium, the higher uranium concentration gave lower growth of mycelia, and no fruiting body was observed. In the rice bran medium, the fruiting body was grown at U concentrations up to 1000 mg/L. The AA and XRF analysis showed that uranium taken up in the fruiting body was below the detection limit. The SEM-EDS analysis indicated that U was distributed in the limited region and was not transported to the mycelia far from U containing medium. It is concluded that uranium affects the growth of Pleurotus sp., and little uranium is taken up by Pleurotus sp. during the growth of both mycelia and fruiting body. (author)

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.)

Uranium tailings research at the Canada Centre for Mineral and Energy Technology (CANMET)

International Nuclear Information System (INIS)

Haw, V.A.; Ritcey, G.M.; Skeaff, J.M.; Dave, N.; Silver, M.

1982-09-01

There are over 100 million metric tons of uranium tailings on the surface of Canada, an amount that is expected to increase threefold by the end of the century. Because of their potential hazard to the environment and man, the Canada Centre for Mineral and Energy Technology (CANMET) began a major program ten years ago to examine the problem of uranium tailings management. Vegetation of uranium tailings has been successful using seed mixtures planted on the tailings surface pretreated by lime and fertilizer. Lysimeter tests on uranium tailings have demonstrated that surface treatment and the presence or absence of bacteria have a marked effect on the flow and chemistry of seepage water. Hydrogeochemical studies of the tailings have shown that acid conditions prevail in the upper zone of the tailings (i.e., above the water table) and that both radioactive and other toxic chemicals are concentrated near the bottom of the tailings. Work has been done in cooperation with others on the precipitation and removal of 226 Ra from tailings water effluent by BaCl 2 . Investigation into pre-concentrating the ore prior to acid leaching has demonstrated that virtually all the radionuclides and sulphides can be concentrated into a fraction amounting to from 30 to 40 percent of the original feed, leaving a relatively clean tailing. We are still far from our objective of demonstrating, with reasonable assurance, effective methods for the long-term management of uranium tailings. An accelerated program is outlined

The life of some metallic uranium based fuel elements; Duree de vie de quelques combustibles a base d'uranium metal

Energy Technology Data Exchange (ETDEWEB)

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

1958-07-01

Description of some theoretical and experimental data concerning the design and most economic preparation of metallic uranium based fuel elements, which are intended to produce an energy of 3 kW days/g of uranium in a thermal reactor, at a sufficiently high mean temperature. Experimental results obtained by testing by analogy or by actually trying out fuel elements obtained by alloying uranium with other metals in proportions such that the resistance to deformation of the alloy produced is much higher than that of pure metallic uranium and that the thermal utilisation factor is only slightly different from that of the uranium. (author) [French] Description de quelques donnees theoriques et experimentales concernant la conception et la preparation la plus economique d'elements combustibles a base d'uranium metallique naturel, destines a degager dans un reacteur thermique une energie de l'ordre de 3 kWj/g d'uranium a une temperature moyenne suffisamment elevee. Resultats experimentaux acquis par tests analogiques ou reels sur combustibles obtenus par alliage de l'uranium avec des elements metalliques en proportions telles que la resistance a la deformation soit bien superieure a celle de l'uranium metal pur et que le facteur propre d'utilisation thermique n ne soit que peu affecte. (auteur)

Depleted uranium in the environment - an issue of concern?

International Nuclear Information System (INIS)

Stegnar, P.; Benedik, Lj.

2002-01-01

Natural uranium (U) occurs in soils in typical concentrations of a few parts per milion. U-238 is the most abundant isotope in natural uranium (fraction by weight in natural uranium is 99.28%) and decays into other radioactive elements. A radioactive waste product of uranium enrichment is known as 'depleted uranium' (DU) which is basically natural uranium in which the fissionable U-235 isotopic content has been reduced from 0.71% to 0.2-0.3%. It is practically pure alpha emitter, only selected (in=growth) daughter products are gammaand beta emitters. Comparison of radioactivity shows that the total activity in 1mg of natural uranium is 25.28 Bq and in1 mg of DU is 14.80 Bq. The radioactivity of DU is 60% of that of natural uranium. Currently in the USA alone, there are about 600.000 tonnes of DU in storage. DU is cheap and it is available in large quantities. It is widely used as ballast or counterbalances in ships and aircrafts, as radiation shielding and in non-nuclear civil applications requiring hugh density material. (author)

X-ray photoelectron spectroscopy of the uranium/oxygen system: Part 13

International Nuclear Information System (INIS)

Allen, G.C.; Stevens, J.C.H.

1987-02-01

The reaction between commercial H 2 and uranium metal leads to the formation of UO 2 due to traces of water vapour or oxygen. When extremely pure H 2 is used uranium hydride may be formed but, even with 99.9999% H 2 , uranium dioxide forms preferentially. The present work identifies the presence of UH 3 in the X-ray photoelectron spectrum of a uranium sample which has been exposed to ∼ 5 mbar H 2 at ∼ 200 0 C for 1 hour. This spectrum indicates that the hydride possesses a high degree of covalency, since the oxidation state of uranium in UH 3 appears to be ∼ 1.4. (U.K.)

Study of the Formation of Eutectic Melt of Uranium and Thermal Analysis for the Salt Distillation of Uranium Deposits

International Nuclear Information System (INIS)

Park, Sung Bin; Hwang, Sung Chan; Kang, Young Ho; Park, Ki Min; Jun, Wan Gi; Lee, Han Soo; Cho, Dong Wook

2010-01-01

Uranium deposits from an electrorefining process contain about 30% salt. In order to recover pure uranium and transform it into an ingot, the salts have to be removed from the uranium deposits. Major process variables for the salt distillation process of the uranium deposits are hold temperature and vacuum pressure. Effects of the variables on the salt removal efficiency were studied in the previous study 1. By applying the Hertz-Langmuir relation to the salt evaporation of the uranium deposits, the evaporation coefficients were obtained at the various conditions. The operational conditions for achieving above 99% salt removal were deduced. The salt distilled uranium deposits tend to form the eutectic melt with iron, nickel, chromium for structural material of salt evaporator. In this study, we investigated the hold temperature limitation in order to prevent the formation of the eutectic melt between uranium and other metals. The reactions between the uranium metal and stainless steel were tested at various conditions. And for enhancing the evaporation rate of the salt and the efficient recovery of the distilled salt, the thermal analysis of the salt distiller was conducted by using commercial CFX software. From the thermal analysis, the effect of Ar gas flow on the evaporation of the salt was studied.

Impurities determination in uranium eluates by total reflection X-ray fluorescence

International Nuclear Information System (INIS)

Vazquez, Cristina; Bellavigna, Horacio J.; Eppis, Maria R.; Ramella, Jose L.

1999-01-01

The chemical control of impurities in nuclear materials is indispensable in order to assure an efficient operation of the reactors. The maximum concentration admitted depends of the elements and in most cases are in the parts per billion range. Conventional analytical methods require a pre-concentration treatment of the sample and a previous separation of the matrix (uranium). This paper investigates the use of the total reflection X-ray fluorescence as an alternative methodology for the determination of impurities in nuclear materials, namely K, Ca, Ti, Cr, Mn, Fe, Ni, Cu and As. The detection limits obtained were in the range of 0.1 to 20 ng/ml for a 1000 seconds counting time. (author)

Evolution of the uranium industry in France; Evolution de l'industrie de l'uranium en France

Energy Technology Data Exchange (ETDEWEB)

Maget, P; Vertes, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires; Bazile, F [Societe industrielle des minerais de l' ouest (France)

1964-07-01

The main feature in the development of the French uranium industry during the last few years is the completion of the programme, already started in 1958, for the equipment of mining units and treatment plants. It was thus possible by 1961, to reach a production capacity of about 2000 T of metal contained in concentrates, and about 1800 T of metal of nuclear purity. The prospecting and research carried on in France by the Commissariat and by private Industry have brought about not only a satisfactory renewal of the reserves under exploitation but also the development of two new uranium-producing regions: one of the usual type in France, in the crystalline formations to the South-East of the Massif Central, the other in the Permian sedimentary formations in the department of l'Herault. Uraniferous concentrates are produced in two forms: -on the one hand two chemical plants run by a combined Commissariat-private industry firm, the Societe Industrielle des Minerais de l'Ouest, produce magnesium uranates by a conventional process, in the Vendee and at la Crouzille; - on the other hand two Commissariat plants, one managed by the same Society in the Forez, the other run directly by the Commissariat at Gueugnon in the Grury mining district, at present inactive, produce uranyl nitrate: the former from ore extracted in the Forez region, the latter from magnesium uranate pre-concentrates imported from Gabon. Two Commissariat plants convert the concentrates into a product of nuclear purity: - one at le Bouchet, run by the C.E.A., which also deals with development studies, - the other at Malvesi, managed by a Commissariat-private industry combine, the Societe de Raffinage de l'Uranium. This latter has a production capacity about double that of le Bouchet and uses the same manufacturing processes. The bulk of the uranium metal is still produced by calcium reduction, but the le Bouchet plant is already equipped for magnesium reduction and is using this process. Uranium fluoride

An alternative procedure for uranium analysis in drinking water using AQUALIX columns: application to varied French bottled waters.

Science.gov (United States)

Bouvier-Capely, C; Bonthonneau, J P; Dadache, E; Rebière, F

2014-01-01

The general population is chronically exposed to uranium ((234)U, (235)U, and (238)U) and polonium ((210)Po) mainly through day-to-day food and beverage intake. The measurement of these naturally-occurring radionuclides in drinking water is important to assess their health impact. In this work the applicability of calix[6]arene-derivatives columns for uranium analysis in drinking water was investigated. A simple and effective method was proposed on a specific column called AQUALIX, for the separation and preconcentration of U from drinking water. This procedure is suitable for routine analysis and the analysis time is considerably shortened (around 4h) by combining the separation on AQUALIX with fast ICP-MS measurement. This new method was tested on different French bottled waters (still mineral water, sparkling mineral water, and spring water). Then, the case of simultaneous presence of uranium and polonium in water was considered due to interferences in alpha spectrometry measurement. A protocol was proposed using a first usual step of spontaneous deposition of polonium on silver disc in order to separate Po, followed by the uranium extraction on AQUALIX column before alpha spectrometry counting. © 2013 Published by Elsevier B.V.

Liquid chromatographic determination of uranium in seawater with coulometric detection

International Nuclear Information System (INIS)

Maekoya, Chiaki; Takata, Yoshinori

1980-01-01

A method of the separation with anion-exchange chromatography and of the coulometric detection of uranium in seawater was investigated. The size of the separation column used was 9 mm in inside diameter and 100 mm in length, and strong basic anion-exchange resin (Hitachi No. 2632) of carbonate form was packed in the column. A concentrator with two mini-columns in which the same resin was packed was applied for the preconcentration of uranium in seawater containing 20 g of potassium thiocyanate and 10 ml of hydrochloric acid per liter. Good result was obtained when a mixed solution of sodium carbonate (0.12 mol/l), sodium bicarbonate (0.08 mol/l), sodium bisulfite (0.03 mol/l) and sodium chloride (0.5 mol/l) was used as an eluent for the separation of uranium from vanadium. Sodium bisulfite was of use for dropping the background current based on an electrochemical reduction of dissolved oxygen. Sodium bicarbonate acted as an eliminator of an unknown peak by its bufferise effect. The optimum working electrode potential for the detection was -1.45 V vs. ferri-ferrocyanide. The detection limit was 3.2 x 10 -10 mol (80 ngU). The coefficient of variation at 3.0 ppb was about 4% (n=5) for seawater analysis. And the analysis time was approximately 1.5 hours. (author)

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

A critique of the Saskatchewan uranium royalty

International Nuclear Information System (INIS)

Kwon, O.Y.

1982-01-01

The Saskatchewan uranium royalty system has been in operation since 1976. The objectives of the system are: 1) to ensure a minimum return to the province from extraction of uranium; 2) to capture a fair share of the 'excess' profits; 3) to provide the producers with an adequate rate of return on investment; and 4) to leave marginal production decisions unaffected. The last three objectives are intended to capture pure profits or economic rents without distorting uranium developments. Taxation as an instrument for effecting such an objective is referred to as neutral taxation. This paper evaluates the Saskatchewan system first in the light of neutral taxation, and second in light of the objective of ensuring a minimum return to the province

Investigations on the application of the ion-exchanger SRAFION NMRR for the enrichment and separation of uranium and other trace elements from sea water

International Nuclear Information System (INIS)

Ochsenkuehn-Petropulu, M.; Parissakis, G.

1985-01-01

It can be demonstrated, in batch and continuous flow experiments that the ion-exchanger SRAFION NMRR is suitable for the preconcentration and separation of uranium and other trace elements (such as Mo, V, Ag, Cr, Cu, Fe, Mn, Ni, Pb and Zn) from sea water. Among the different eluates, 0.5 N HNO 3 was selected. Uranium was extracted from the eluate with 0.1 M TOPO/cyclohexane and analysed in the organic extract by differential-pulse polarography, while the other elements were directly determined in the eluate by AAS. It was possible to determine the above mentioned trace elements by this absorption-elution process in the sea water of the Isthmus of Corinth area, Greece. (orig.) [de

The pretreatment of uranium ores by physical processing; Les problemes de la preconcentration des minerais d'uranium par voie physique

Energy Technology Data Exchange (ETDEWEB)

Vuchot, L.; Ginocchio, A.; Hubert, G.; Roques, E.; Sandier, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

After giving an outline of the classical means of physical processing - granulometry, gravimetry, flotation, magnetism, electrostatics, the authors study the methods peculiar to radioactive ores: pretreatment in batches (counting cylinders) or stone by stone (electronic sorting belt). The three factors to be considered in any treatment operation are studied (cost of the operation, metal recovery, ratio of concentration), as well as their bearing on the cost and the productivity of the following operations. Making use of radioactivity in order to find out instantaneously the approximate grade of the obtained product makes it possible to reduce costs and improve results by setting up total automation. (author) [French] Apres un apercu des procedes classiques de concentration physique des minerais - granulometrie, gravimetrie, flottation, magnetisme et electrostatique, les auteurs s'attachent aux methodes propres aux minerais radioactifs: preconcentration par lots (cylindre de comptage) ou caillou par caillou (bande de triage electronique). Les trois facteurs a considerer lors de toute operation de traitement sont etudies (prix de revient de l'operation, rendement metal et rendement poids), ainsi que leurs repercussions sur les prix de revient et rendements des traitements ulterieurs. L'utilisation de la radioactivite pour determiner instantanement la teneur approximative des produits obtenus permet d'envisager de reduire les prix de revient et d'ameliorer les resultats par une automatisation totale. (auteur)

Preconcentration of plutonium and americium using the Actinide-CUTM Resin for human tissue analysis

International Nuclear Information System (INIS)

Qu, H.; Stuit, D.; Glover, S.E.; Love, S.F.; Filby, R.H.; Washington State Univ., Pullman, WA

1998-01-01

A method for the preconcentration of Am and Pu from human tissue solutions (liver, lung, bone etc) using the Actinide-CU Resin (EIChroM Industries) has been developed for their alpha-spectrometric determination. With near 100% recoveries were obtained by preconcentration, subsequent decomposition methods for eluent were developed. Good agreement for Pu and Am determination with the USTUR anion-exchange/solvent extraction method was demonstrated using previously analyzed human tissue solutions and NIST SRMs. The advantages of the preconcentration method applied to human tissue analysis are simplicity of operation, shorter analysis time compared to anion exchange/solvent extraction methods, and capacity to analyze large tissue samples (up to 15 g bone ash per analysis and 500 g soft tissue). (author)

Biosorption of uranium by immobilized cells of Rhodotorula glutinis

International Nuclear Information System (INIS)

Jing Bai; Zhan Li; Fangli Fan; Xiaolei Wu; Xiaojie Yin; Longlong Tian; Zhi Qin; Junsheng Guo

2014-01-01

Biosorption of uranium ions from diluted solution (≤40 mg L -1 ) onto immobilized cells of Rhodotorula glutinis was investigated in a batch system. Equilibrium, kinetic and thermodynamic studies were conducted by considering the effect of initial uranium concentration, contact time and temperature. Non-linear forms of Langmuir, Freundlich and Sips isotherm models were used to fit the equilibrium data, Sips model was designated as the best one. Kinetic data were simulated by non-linear pseudo-first-order, pseudo-second-order and intra-particle diffusion equations. Pseudo-first-order kinetic equation described the experimental data better than pseudo-second-order equation and intra-particle diffusion equation can fit the kinetic data with two independent curves. Thermodynamic parameters, including ∆H 0, ∆G 0 and ∆S 0, were evaluated, the sorption process was determined to be spontaneous and endothermic. Uranium sorption from pure uranium solutions and uranium pit wastewater by immobilized biomass and blank beads, as well as the regeneration results indicated that immobilized R. glutinis can be use to recovery uranium from uranium pit wastewater. (author)

A Fully-Integrated MEMS Preconcentrator for Rapid Gas Sampling (Preprint)

National Research Council Canada - National Science Library

Bae, Byunghoon; Yeom, Junghoon; Radadia, Adarsh D; Masel, Richard I; Shannon, Mark A

2006-01-01

.... The unprecedented speed of this preconcentrator (chemical warfare agents, toxic industrial compounds (TICs), and other volatile compounds in seconds, rather than tens of minutes with conventional systems.

Standard test method for analysis of total and isotopic uranium and total thorium in soils by inductively coupled plasma-mass spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 This test method covers the measurement of total uranium (U) and thorium (Th) concentrations in soils, as well as the determination of the isotopic weight percentages of 234U, 235U, 236U, and 238U, thereby allowing for the calculation of individual isotopic uranium activity or total uranium activity. This inductively coupled plasma-mass spectroscopy (ICP-MS) method is intended as an alternative analysis to methods such as alpha spectroscopy or thermal ionization mass spectroscopy (TIMS). Also, while this test method covers only those isotopes listed above, the instrumental technique may be expanded to cover other long-lived radioisotopes since the preparation technique includes the preconcentration of the actinide series of elements. The resultant sample volume can be further reduced for introduction into the ICP-MS via an electrothermal vaporization (ETV) unit or other sample introduction device, even though the standard peristaltic pump introduction is applied for this test method. The sample preparatio...

Original geochemical types and epigenetic alteration of rocks in prospecting target stratum for uranium deposit in the southeast of Songliao basin

International Nuclear Information System (INIS)

Lin Jinrong; Tian Hua; Dong Wenming; Xia Yuliang; Qi Daneng; Yao Shancong; Zheng Jiwei

2009-01-01

By comprehensive analysis on informations of regional geology and evaluating drillhole works of uranium resources in the southeast of Songliao basin, lithofacies-palaeogeography features, lithologies and sandbody characteristics of target layes in Quantou formation, Yaojia formation and Sifangtai formation have been basically found out. By research on geochemical environment of rocks in target layez, types of original geochemistry and epigenetic alteration have been identified and classified. The types of original geochemistry have been divided into types of original oxidation and original reduction, and the types of epigenetic alteration have been divided into types of reduction by oil-gas and coalbed gas and epigenetic oxidation. By comparative study on mineral and chemical characteristics of original geochemistry and epigenetic oxidation, identification marks for oil-gas and coalbed gas reduced epigenetic oxidation have been proposed. It is proposed that uranium was strongly pre-concentrated in original sandstone that bearing carboniferous matter, and reduction by oil-gas and coalbed gas made uranium superimpose and concentrate in alterated rocks. (authors)

Preconcentration and extraction of copper(II) on activated carbon ...

African Journals Online (AJOL)

Activated carbon modified method was used for the preconcentration and ... in real samples such as tap water, wastewater and a synthetic water sample by flame ... KEY WORDS: Copper(II), Solid phase extraction, Activated carbon, Flame ...

Thermal properties of nonstoichiometry uranium dioxide

Science.gov (United States)

Kavazauri, R.; Pokrovskiy, S. A.; Baranov, V. G.; Tenishev, A. V.

2016-04-01

In this paper, was developed a method of oxidation pure uranium dioxide to a predetermined deviation from the stoichiometry. Oxidation was carried out using the thermogravimetric method on NETZSCH STA 409 CD with a solid electrolyte galvanic cell for controlling the oxygen potential of the environment. 4 samples uranium oxide were obtained with a different ratio of oxygen-to-metal: O / U = 2.002, O / U = 2.005, O / U = 2.015, O / U = 2.033. For the obtained samples were determined basic thermal characteristics of the heat capacity, thermal diffusivity, thermal conductivity. The error of heat capacity determination is equal to 5%. Thermal diffusivity and thermal conductivity of the samples decreased with increasing deviation from stoichiometry. For the sample with O / M = 2.033, difference of both values with those of stoichiometric uranium dioxide is close to 50%.

Initial and transition cycle development for KALIMER uranium fueled core

International Nuclear Information System (INIS)

Kim, Sang Ji; Kim, Young In; Kim, Young Jin; Park, Chang Kue

1998-01-01

An economic and safe equilibrium Uranium metallic fuelled core having been established, strategic loading schemes for initial and transition cycles to early reach target equilibrium cycles are suggested for U-U and U-Pu transition cycles. An iterative method to find initial core enrichment splits is developed. With non-uniform feed enrichments at the initial core adopted, this iterative method shows KALIMER can reach Uranium equilibrium cycles just after 4 reloads, keeping feed enrichment unchanged from cycle 2. Recycling of self-generated Pu is not sufficient to make KALIMER a pure Pu equilibrium core even after 56 reloads. equilibrium cycles are suggested for U-U and U-Pu transition cycles. An iterative method to find initial core enrichment splits is developed. With non-uniform feed enrichments at the initial core adopted, this iterative method shows KALIMER can reach Uranium equilibrium cycles just after 4 reloads, keeping feed enrichment unchanged from cycle 2. Recycling of self-generated Pu is not sufficient to make KALIMER a pure Pu equilibrium core even after 56 reloads

Investigation of the synergic effect of some neutral organophosphoric compounds on the extraction of uranium from phosphoric acid solutions by D1-(2-Ethyl Hexyl) phosphoric acid

International Nuclear Information System (INIS)

Stas, J.; Khorfan, S.; Koudsi, Y.

1998-05-01

The extraction of uranium (VI) from pure phosphoric acid media by D2EHPA/Kerosene has been studied. The mechanism of the extraction was found as follows: The logarithm of the equilibrium constant of the extraction (LogKex) was found (3.06), (3.32), (3.24), (3.3) for the following phosphoric acid concentrations respectively (1), (2), (3), (4) Mol/1, and the enthalpy change DELTA H was found (-100.68 kj/mol). (-76 kj/mol) for (1), (2) mol/1 phosphoric acid concentrations. The synergic effect of TOPO, TBP, and TBPI with DEHPA have been studied during the extraction of uranium from pure phosphoric acid and Syrian commercial phosphoric acid. The synergic effect increases as follows: TBP< TBPI<< TOPO (In pure phosphoric acid), TBPI approx TBP<< TOPO (In Syrian commercial phosphoric acid). The difficulty of extracting uranium (VI) from Syrian commercial phosphoric acid in comparison with pure phosphoric acid is due to the presence of several impurities capable of complexing uranium, and a small amounts of solid and organic matters, all these are factors which reduce the distribution coefficient of uranium. (Author)

On-line preconcentration and determination of chromium in parenteral solutions by inductively coupled plasma optical emission spectrometry

International Nuclear Information System (INIS)

Gil, R.A.; Cerutti, S.; Gasquez, J.A.; Olsina, R.A.; Martinez, L.D.

2005-01-01

A method for the preconcentration and speciation of chromium was developed. On-line preconcentration and determination were obtained using inductively coupled plasma optical emission spectrometry (ICP-OES) coupled with flow injection. To determinate the chromium (III) present in parenteral solutions, chromium was retained on activated carbon at pH 5.0. On the other hand, a step of reduction was necessary in order to determine total chromium content. The Cr(VI) concentration was then determined by difference between the total chromium concentration and that of Cr(III). A sensitivity enrichment factor of 70-fold was obtained with respect to the chromium determination by ICP-OES without preconcentration. The detection limit for the preconcentration of 25 ml of sample was 29 ng l -1 . The precision for the 10 replicate determinations at the 5 μg l -1 Cr level was 2.3% relative standard deviation, calculated with the peak heights. The calibration graph using the preconcentration method for chromium species was linear with a correlation coefficient of 0.9995 at levels near the detection limits up to at least 60 μg l -1 . The method can be applied to the determination and speciation of chromium in parenteral solutions

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

Criticality analyses of regions containing uranium in the earth history

International Nuclear Information System (INIS)

Ravnik, M.

2005-01-01

Investigations of necessary conditions for a self-sustained chain reaction in the Earth inner regions hypothetically containing uranium is presented for the time interval from Earth formation to present time. It is determined that criticality was theoretically possible up to 2.5 Ga before present if uranium concentrated in pure form. In the early geological history (4 Ga before present) the self-sustained criticality could occur even if uranium was diluted up to 1:20 by the average core material or 1:60 by the average mantle material. If other metallic materials of similar density as uranium (e.g., Au, W) or similar atomic weight (e.g., Th) concentrated from the primordial mixture in equal proportion as uranium, criticality was not possible for any period in Earth history provided that the basic material contained no light nuclides (H, C). Criticality in the Earth inner regions could have established only if uranium concentrated from the basic material more effectively than elements of similar density or atomic number. (orig.)

Process development study on production of uranium metal from monazite sourced crude uranium tetra-fluoride

International Nuclear Information System (INIS)

Chowdhury, S; Satpati, S.K.; Hareendran, K.N.; Roy, S.B.

2014-01-01

Development of an economic process for recovery, process flow sheet development, purification and further conversion to nuclear grade uranium metal from the crude UF 4 has been a technological challenge and the present paper, discusses the same.The developed flow-sheet is a combination of hydrometallurgical and pyrometallurgical processes. Crude UF 4 is converted to uranium di-oxide (UO 2 ) by chemical conversion route and UO 2 produced is made fluoride-free by repeated repulping, followed by solid liquid separation. Uranium di-oxide is then purified by two stages of dissolution and suitable solvent extraction methods to get uranium nitrate pure solution (UNPS). UNPS is then precipitated with air diluted ammonia in a leak tight stirred vessel under controlled operational conditions to obtain ammonium di-uranate (ADU). The ADU is then calcined and reduced to produce metal grade UO 2 followed by hydro-fluorination using anhydrous hydrofluoric acid to obtain metal grade UF 4 with ammonium oxalate insoluble (AOI) content of 4 is essential for critical upstream conversion process. Nuclear grade uranium metal ingot is finally produced by metallothermic reduction process at 650℃ in a closed vessel, called bomb reactor. In the process, metal-slag separation plays an important role for attaining metal purity as well as process yield. Technological as well economic feasibility of indigenously developed process for large scale production of uranium metal from the crude UF 4 has been established in Bhabha Atomic Research Centre (BARC), India

Processing of Sierra Albarrana uranium ores; Tratamiento de los minerales de uranio de Sierra Albarrana

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Jodra, L; Perez Luina, A; Perarnau, M

1960-07-01

Uranium recovery by hydrometallurgy from brannerite, found in Hornachuelos (Cordoba) is described. It has been studied the acid and alkaline leaching and salt roasting, proving as more satisfactory the acid leaching. Besides the uranium solubilization by acid leaching, is described the further process to obtain pure uranyl nitrate. (Author)

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

Trends in preconcentration procedures for metal determination using atomic spectrometry techniques

International Nuclear Information System (INIS)

Godoi Pereira, M. de; Arruda, M.A.Z.

2003-01-01

Methods for metal preconcentration are often described in the literature. However, purposes are often different, depending on whether the methods are applied in environmental, clinical or technological fields. The respective method needs to be efficient, give high sensitivity, and ideally also is selective which is useful when used in combination with atomic spectroscopy. This review presents the actual tendencies in metal preconcentration using techniques such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), hydride generation atomic absorption spectrometry (HGAAS), inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS). Procedures based on related to electrochemical, coprecipitation/precipitation, liquid-liquid and solid-liquid extraction and atom trapping mechanisms are presented. (author)

Separation and Preconcentration of Trace Amounts of Nickel from Aqueous Samples

Directory of Open Access Journals (Sweden)

Reyhaneh Rahnama

2018-05-01

Full Text Available In this paper, a new method for preconcentration and measurement of trace amounts of nickel in aqueous samples by magnetic solid phase extraction (MSPE via magnetic carbon nanotubes (Mag-CNTs was developed. In order to increase selectivity, α-Furildioxime was used as chelating agent. In order to do extraction, optimum amount of ligand was added to the nickel sample and pH was set on 9, then 7 ml. of adsorbent was added and stirred for 15 minutes. After that, aqueous phase and adsorbent were separated by a strong magnet. Finally, the absorption was measured via flame atomic absorption spectrometry by analyte elution from the absorbent with an appropriate solution. Parameters affecting the extraction and preconcentration of nickel were investigated and optimized. Under optimum conditions, the calibration curve was linear in concentration range from 2.5 to 375 µg L-1 and the detection limit was 0.8 µg L-1 of nickel. The method was applied for determination of nickel in aqueous samples. The relative efficiency values of nickel measurement in aqueous samples were from 98.7% to 102.1%.  Results indicated that Mag-CNTs can be used as an effective and inexpensive absorbent for preconcentration and extraction of nickel from actual samples.

Sodium dodecyl sulfate coated alumina modified with a new Schiff's base as a uranyl ion selective adsorbent

Energy Technology Data Exchange (ETDEWEB)

Tashkhourian, J., E-mail: tashkhourian@susc.ac.ir [Department of Chemistry, College of Science, Shiraz University, 71454 Shiraz (Iran, Islamic Republic of); Moradi Abdoluosofi, L.; Pakniat, M. [Department of Chemistry, Faculty of Science, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Montazerozohori, M. [Department of Chemistry, Faculty of Science, Yasouj University, Yasouj (Iran, Islamic Republic of)

2011-03-15

A simple and selective method was used for the preconcentration and determination of uranium(VI) by solid-phase extraction (SPE). In this method, a column of alumina modified with sodium dodecyl sulfate (SDS) and a new Schiff's base ligand was prepared for the preconcentration of trace uranyl(VI) from water samples. The uranium(VI) was completely eluted with HCl 2 M and determined by a spectrophotometeric method with Arsenazo(III). The preconcentration steps were studied with regard to experimental parameters such as amount of extractant, type, volume and concentration of eluent, pH, flow rate of sample source and tolerance limit of diverse ions on the recovery of uranyl ion. A preconcentration factor more than 200 was achieved and the average recovery of uranyl(VI) was 99.5%. The relative standard deviation was 1.1% for 10 replicate determinations of uranyl(VI) ion in a solution with a concentration of 5 {mu}g mL{sup -1}. This method was successfully used for the determination of spiked uranium in natural water samples.

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.

Preconcentration of traces of radionuclides with sorbents based on spherical polyurethane membrane systems in the analysis of environmental samples

International Nuclear Information System (INIS)

Palagyi, S.; Braun, T.

1986-01-01

In the paper the importance of preconcentration and a permanent need for efficient preconcentrating agents in environmental analysis are pointed out. The increased attention is devoted to the foamed polyurethane sorbents as a novel advance in the separation chemistry. The paper has two main aims. The first is to present a survey of recent applications of unloaded and reagent loaded open-cell type resilient polyurethane foams to the separation and preconcentration of radionuclides from environmental samples. The second is to show the newest results in the use of these foams for the preconcentration and determination of traces of some mainly inorganic species in environmental samples by radioanalytical techniques. Some future possibilities of the use of polyurethane foams in trace elemental determinations in environmental analysis are also outlined. (author)

Uraniferous preconcentrations

International Nuclear Information System (INIS)

Pagel, M.

1983-01-01

Models applied to discordance deposit genesis are generally based on superficial or deep leaching of uranium rich metamorphic, granitic or sedimentary rocks. Available data on Saskatchewan North East Australia are compared. They are essentially on geochemistry and accurate mineralogic data are needed [fr

Force fields of charged particles in micro-nanofluidic preconcentration systems

Science.gov (United States)

Gong, Lingyan; Ouyang, Wei; Li, Zirui; Han, Jongyoon

2017-12-01

Electrokinetic concentration devices based on the ion concentration polarization (ICP) phenomenon have drawn much attention due to their simple setup, high enrichment factor, and easy integration with many subsequent processes, such as separation, reaction, and extraction etc. Despite significant progress in the experimental research, fundamental understanding and detailed modeling of the preconcentration systems is still lacking. The mechanism of the electrokinetic trapping of charged particles is currently limited to the force balance analysis between the electric force and fluid drag force in an over-simplified one-dimensional (1D) model, which misses many signatures of the actual system. This letter studies the particle trapping phenomena that are not explainable in the 1D model through the calculation of the two-dimensional (2D) force fields. The trapping of charged particles is shown to significantly distort the electric field and fluid flow pattern, which in turn leads to the different trapping behaviors of particles of different sizes. The mechanisms behind the protrusions and instability of the focused band, which are important factors determining overall preconcentration efficiency, are revealed through analyzing the rotating fluxes of particles in the vicinity of the ion-selective membrane. The differences in the enrichment factors of differently sized particles are understood through the interplay between the electric force and convective fluid flow. These results provide insights into the electrokinetic concentration effect, which could facilitate the design and optimization of ICP-based preconcentration systems.

NAA using Cf-252 after preconcentration

International Nuclear Information System (INIS)

Panyo, O.; Moebius, S.; Keller, C.

1988-01-01

Neutron activation analysis (NAA) with thermal neutron using Cf-252 sources was applied to elemental analysis of elements in water samples. A high-resolution Ge(Li) detector was employed for gamma-radiation detection. Both suspended particulate matter and liquid fraction were investigated after filtration. Preconcentration method by co-precipitation using iron (III) hydroxide and oxine were chosen for use. Elements which were considered to be able to detect in the present study are Al, As, Cl, K, Mg, Mn, Na, Sr, Ti, U, V and Zn

Performance and stability of low-cost dye-sensitized solar cell based crude and pre-concentrated anthocyanins: Combined experimental and DFT/TDDFT study

Science.gov (United States)

Chaiamornnugool, Phrompak; Tontapha, Sarawut; Phatchana, Ratchanee; Ratchapolthavisin, Nattawat; Kanokmedhakul, Somdej; Sang-aroon, Wichien; Amornkitbamrung, Vittaya

2017-01-01

The low cost DSSCs utilized by crude and pre-concentrated anthocyanins extracted from six anthocyanin-rich samples including mangosteen pericarp, roselle, red cabbage, Thai berry, black rice and blue pea were fabricated. Their photo-to-current conversion efficiencies and stability were examined. Pre-concentrated extracts were obtained by solid phase extraction (SPE) using C18 cartridge. The results obviously showed that all pre-concentrated extracts performed on photovoltaic performances in DSSCs better than crude extracts except for mangosteen pericarp. The DSSC sensitized by pre-concentrated anthocyanin from roselle and red cabbage showed maximum current efficiency η = 0.71% while DSSC sensitized by crude anthocyanin from mangosteen pericarp reached maximum efficiency η = 0.97%. In addition, pre-concentrated extract based cells possess more stability than those of crude extract based cells. This indicates that pre-concentration of anthocyanin via SPE method is very effective for DSSCs based on good photovoltaic performance and stability. The DFT/TDDFT calculations of electronic and photoelectrochemical properties of the major anthocyanins found in the samples are employed to support the experimental results.

Uranium tailings research at the Canada Centre for Mineral and Energy Technology

International Nuclear Information System (INIS)

Haw, V.A.; Ritcey, G.M.; Skeaff, J.M.; Dave, N.; Silver, M.

1983-01-01

There are over 100 million tonnes of uranium tailings on the surface of Canada, an amount that is expected to increase threefold by the end of the century. Because of their potential hazard to the environment and man, the Canada Centre for Mineral and Energy Technology (CANMET) began a major programme ten years ago, to examine the problem of uranium tailings management. Work to date has shown that: (1) Vegetation of uranium tailings has been successful using seed mixtures planted on the tailings surface pre-treated by lime and fertilizer; (2) Lysimeter tests on uranium tailings have demonstrated that surface treatment and the presence or absence of bacteria have a marked effect on the flow and chemistry of seepage water; (3) Hydrogeochemical studies of the tailings have shown that acid conditions prevail in the upper zone of the tailings (i.e. above the water table) and that both radioactive and other toxic chemicals are concentrated near the bottom of the tailings; (4) Work has been done in co-operation with others on the precipitation and removal of 226 Ra from tailings water effluent by BaCl 2 . The purpose of this work is to improve control of the total radium content of water discharged to drainage systems by mechanical means. (5) Investigation into pre-concentrating the ore prior to acid leaching has demonstrated that virtually all the radionuclides and sulphides can be concentrated into a fraction amounting to from 30 to 40 per cent of the original feed, leaving a relatively clean tailing. The authors are still far from their objective of demonstrating, with reasonable assurance, effective methods for the long-term management of uranium tailings. An accelerated programme is outlined. (author)

Pre-Concentration of Vanadium from Stone Coal by Gravity Using Fine Mineral Spiral

Directory of Open Access Journals (Sweden)

Xin Liu

2016-08-01

Full Text Available Due to the low grade of V2O5 in stone coal, the existing vanadium extraction technologies face challenges in terms of large handling capacity, high acid consumption and production cost. The pre-concentration of vanadium from stone coal before the extraction process is an effective method to reduce cost. In this study, detailed mineral characterization of stone coal was investigated. It has been confirmed that the vanadium mainly occurs in muscovite and illite. A significant demand for an effective pre-concentration process with simple manipulation for discarding quartz and other gangue minerals is expected. Based on the mineralogical study, a new vanadium pre-concentration process using a fine mineral spiral was investigated. The experimental results showed that the separation process, which was comprised of a rougher and scavenger, could efficiently discard quartz, pyrite and apatite. A final concentrate with V2O5 grade of 1.02% and recovery of 89.6% could be obtained, with 26.9% of the raw ore being discarded as final tailings.

Identification of Uranium Minerals in Natural U-Bearing Rocks Using Infrared Reflectance Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Beiswenger, Toya N. [Pacific Northwest National Laboratory, Richland, WA, USA; Gallagher, Neal B. [Eigenvector Research, Inc., Manson, WA, USA; Myers, Tanya L. [Pacific Northwest National Laboratory, Richland, WA, USA; Szecsody, James E. [Pacific Northwest National Laboratory, Richland, WA, USA; Tonkyn, Russell G. [Pacific Northwest National Laboratory, Richland, WA, USA; Su, Yin-Fong [Pacific Northwest National Laboratory, Richland, WA, USA; Sweet, Lucas E. [Pacific Northwest National Laboratory, Richland, WA, USA; Lewallen, Tricia A. [Pacific Northwest National Laboratory, Richland, WA, USA; Johnson, Timothy J. [Pacific Northwest National Laboratory, Richland, WA, USA

2017-10-24

The identification of minerals, including uranium-bearing minerals, is traditionally a labor-intensive-process using x-ray diffraction (XRD), fluorescence, or other solid-phase and wet chemical techniques. While handheld XRD and fluorescence instruments can aid in field identification, handheld infrared reflectance spectrometers can also be used in industrial or field environments, with rapid, non-destructive identification possible via spectral analysis of the solid’s reflectance spectrum. We have recently developed standard laboratory measurement methods for the infrared (IR) reflectance of solids and have investigated using these techniques for the identification of uranium-bearing minerals, using XRD methods for ground-truth. Due to the rich colors of such species, including distinctive spectroscopic signatures in the infrared, identification is facile and specific, both for samples that are pure or are partially composed of uranium (e.g. boltwoodite, schoepite, tyuyamunite, carnotite, etc.) or non-uranium minerals. The method can be used to detect not only pure and partial minerals, but is quite sensitive to chemical change such as hydration (e.g. schoepite). We have further applied statistical methods, in particular classical least squares (CLS) and multivariate curve resolution (MCR) for discrimination of such uranium minerals and two uranium pure chemicals (U3O8 and UO2) against common background materials (e.g. silica sand, asphalt, calcite, K-feldspar) with good success. Each mineral contains unique infrared spectral features; some of the IR features are similar or common to entire classes of minerals, typically arising from similar chemical moieties or functional groups in the minerals: phosphates, sulfates, carbonates, etc. These characteristic 2 infrared bands generate the unique (or class-specific) bands that distinguish the mineral from the interferents or backgrounds. We have observed several cases where the chemical moieties that provide the

Preconcentration and Separation of Mixed-Species Samples Near a Nano-Junction in a Convergent Microchannel

Directory of Open Access Journals (Sweden)

Ping-Hsien Chiu

2015-12-01

Full Text Available A fluidic microchip incorporating a convergent microchannel and a Nafion-nanoporous membrane is proposed for the preconcentration and separation of multi-species samples on a single platform. In the device, sample preconcentration is achieved by means of the ion concentration polarization effect induced at the micro/nano interface under the application of an external electric field, while species separation is achieved by exploiting the different electrophoretic mobilities of the sample components. The experimental results show that the device is capable of detecting C-reactive protein (CRP with an initial concentration as low as 9.50 × 10−6 mg/L given a sufficient preconcentration time and driving voltage. In addition, it is shown that a mixed-species sample consisting of three negatively-charged components (bovine serum albumin (BSA, tetramethylrhodamine(TAMRA isothiocyanate-Dextran and fluorescent polymer beads can be separated and preconcentrated within 20 min given a driving voltage of 100 V across 1 cm microchannel in length. In general, the present results confirm the feasibility of the device for the immunoassay or detection of various multi-species samples under low concentration in the biochemical and biomedical fields. The novel device can therefore improve the detection limit of traditional medical facilities.

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.)

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)

Vapor generation – atomic spectrometric techniques. Expanding frontiers through specific-species preconcentration. A review

International Nuclear Information System (INIS)

Gil, Raúl A.; Pacheco, Pablo H.; Cerutti, Soledad; Martinez, Luis D.

2015-01-01

This article reviews 120 articles found in SCOPUS and specific Journal cites corresponding to the terms ‘preconcentration’; ‘speciation’; ‘vapor generation techniques’ and ‘atomic spectrometry techniques’ in the last 5 years. - Highlights: • Recent advances in vapor generation and atomic spectrometry were reviewed. • Species-specific preconcentration strategies after and before VG were discussed. • New preconcentration and speciation analysis were evaluated within this framework. - Abstract: We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid–liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field

Vapor generation – atomic spectrometric techniques. Expanding frontiers through specific-species preconcentration. A review

Energy Technology Data Exchange (ETDEWEB)

Gil, Raúl A.; Pacheco, Pablo H.; Cerutti, Soledad [Área de Química Analítica, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Instituto de Química de San Luis, INQUISAL, Centro Científico-Tecnológico de San Luis (CCT-San Luis), Consejo Nacional de Investigaciones Científicas y Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Martinez, Luis D., E-mail: ldm@unsl.edu.ar [Área de Química Analítica, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Instituto de Química de San Luis, INQUISAL, Centro Científico-Tecnológico de San Luis (CCT-San Luis), Consejo Nacional de Investigaciones Científicas y Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina)

2015-05-22

This article reviews 120 articles found in SCOPUS and specific Journal cites corresponding to the terms ‘preconcentration’; ‘speciation’; ‘vapor generation techniques’ and ‘atomic spectrometry techniques’ in the last 5 years. - Highlights: • Recent advances in vapor generation and atomic spectrometry were reviewed. • Species-specific preconcentration strategies after and before VG were discussed. • New preconcentration and speciation analysis were evaluated within this framework. - Abstract: We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid–liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field.

Recovery of valuable products from the raffinate of uranium and thorium pilot-plant

International Nuclear Information System (INIS)

Martins, E.A.J.

1990-01-01

IPEN-CNEN/SP has being very active in refining yellow cake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, uranium tetra-and hexa-fluoride in sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major waste to be worked is the raffinate from purification via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid, ammonium nitrate, uranium, thorium and rare earth elements. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium-free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximize the recycle and reuse of the above mentioned chemicals. (author)

Interlaboratory comparison exercise for the determination of uranium by potentiometric titration (first phase)

International Nuclear Information System (INIS)

Verdingh, V.; Le Duigou, Y.

1991-01-01

Upon request of the Esarda working group on low-enriched uranium conversion and fuel fabrication plants an interlaboratory comparison was organized, to assess the precision and accuracy concerning the determination of uranium by the potentiometric titration method. This report presents the results of the first phase of this exercise (pure uranyl-nitrate solutions). The solutions used in this intercomparison have been certified for their uranium content by the CBNM, Geel. Comparison of the laboratory results with the certified values shows excellent, good and fairly good agreement for many of the participating laboratories. 10 tabs., 5 figs., 10 refs

The determination of traces of uranium by means of laser fluorometry

International Nuclear Information System (INIS)

Venter, R.J.

1987-11-01

A method and apparatus were developed to quantitatively determine traces of uranium. A xenon chloride excimer laser was used as an excitation source, which provided various advantages above the conventional light sources. Boxcar integration was used to limit background fluorescence by time-resolved fluorescence spectroscopy. A characteristic wavelength of uranium fluorescence was selected with cut-off filters and a monochromator. The effect of different matrices on the fluorescence of uranium was determined, and the most suitable matrix for quantitative analysis was chosen. A quick and simple method for determining uranium was developed. A combined water sample of industrial effluent was used to evaluate the method. The effect of interfering species, characteristic of the water sample, was examined. A standard addition technique was used to compensate for the effect of the interfering species. The detection limit of uranium in pure water was calculated at three times the standard deviation of the blank sample and was found to be 14 pg/cm 3

Preconcentration and Determination of Antimony in Drinking Water Bottled by Modified Nano-Alumina

Directory of Open Access Journals (Sweden)

M Mohammad Zakizade

2016-01-01

Full Text Available Abstract Introduction: Antimony trioxide (Sb2O3 has been utilized as a catalyst in polyethylene terephtalate (PET production, and the studies conducted on the bottled water has demonstrated that antimony can be leached from PET bottles into drinking water. Methods: In this study, a simple method was applied in order to determine the trace amount of antimony in bottled drinking water based on preconcentration /solid phase extraction. The nano alumina modified with Schiff base ligand was used in regard with Sb preconcentration. The experiments were performed in a continuous system and HCI was used as eluent of Sb ion. Several chemical and flow variables were optimized for a quantitative preconcentration and determination of Sb ion. The atomic absorption spectroscopy was used to determine Sb ion concentration. In order to study the keeping conditions on the leaching of Sb ion from PET plastic, drinking water bottles were kept in different conditions(room temperature, sunny light and -18˚C. Results: The calibration graph was linear in the range of 0.5 to 15.0 ppm Sb with detection limit of 0.055 ppm. The flow rate of sample was optimized in range of 1.0-9.0 mLmin-1 and Sb ion can be quantitatively eluted at 90 Vsample: Veluent retio. Conclusion: The study results revealed that the modified nano alumina is an effective sorbent in regard with absorbing Sb ion from water and HCI 1M can be used as an appropriate eluent. Maximum leaching of Sb ion is observed when the bottled drinking water was exposed to the sun light. Keywords: Antimony; Bottled drinking water; Modified alumina; Preconcentration

New Technique for Speciation of Uranium in Sediments Following Acetate-Stimulated Bioremediation

Energy Technology Data Exchange (ETDEWEB)

2011-06-22

Acetate-stimulated bioremediation is a promising new technique for sequestering toxic uranium contamination from groundwater. The speciation of uranium in sediments after such bioremediation attempts remains unknown as a result of low uranium concentration, and is important to analyzing the stability of sequestered uranium. A new technique was developed for investigating the oxidation state and local molecular structure of uranium from field site sediments using X-Ray Absorption Spectroscopy (XAS), and was implemented at the site of a former uranium mill in Rifle, CO. Glass columns filled with bioactive Rifle sediments were deployed in wells in the contaminated Rifle aquifer and amended with a hexavalent uranium (U(VI)) stock solution to increase uranium concentration while maintaining field conditions. This sediment was harvested and XAS was utilized to analyze the oxidation state and local molecular structure of the uranium in sediment samples. Extended X-Ray Absorption Fine Structure (EXAFS) data was collected and compared to known uranium spectra to determine the local molecular structure of the uranium in the sediment. Fitting was used to determine that the field site sediments did not contain uraninite (UO{sub 2}), indicating that models based on bioreduction using pure bacterial cultures are not accurate for bioremediation in the field. Stability tests on the monomeric tetravalent uranium (U(IV)) produced by bioremediation are needed in order to assess the efficacy of acetate-stimulation bioremediation.

Preparation of chitosan from the shrimp shells and its application for pre-concentration of uranium after cross-linking with epichlorohydrin

Directory of Open Access Journals (Sweden)

Ahmed M. Motawie

2014-06-01

Full Text Available Chitosan (CTS was first prepared by proper treatment of shrimp shells and the cross-linked chitosan (CCTS was then synthesized by its reaction with epichlorohydrin (ECH under alkaline conditions. Adsorption of uranium from aqueous nitrate solution onto CCTS was investigated batch wise. The adsorption isotherm and the adsorption kinetic as well as thermodynamic studies of this adsorption are carried out. The influence factors on uranium (VI adsorption were optimized and were found to include an initial pH of 3 and a contact time of 120 min. The Langmuir adsorption model was then applied for the mathematical description of the obtained adsorption equilibrium and where its data greatly agree with that model and where the maximum adsorption capacity was estimated to be 903 mg/g. Adsorption kinetics data were also tested using pseudo-first-order and pseudo-second-order models and where the studied adsorption followed the latter. In addition, determination of the thermodynamic parameters (ΔG°, ΔH° and ΔS° using van’t Hoff equation has indicated that the prepared CCTS can conveniently be used for uranium adsorption from its aqueous solution.

Long-term uranium supply-demand analyses

International Nuclear Information System (INIS)

1986-12-01

It is the intention of this study to investigate the long-term uranium supply demand situation using a number of supply and demand related assumptions. For supply, these assumptions as used in the Resources and Production Projection (RAPP) model include country economic development status, and consequent lead times for exploration and development, uranium development status, country infrastructure, and uranium resources including the Reasonably Assured (RAR), Estimated Additional, Categories I and II, (EAR-I and II) and Speculative Resource categories. The demand assumptions were based on the ''pure'' reactor strategies developed by the NEA Working Party on Nuclear Fuel Cycle Requirements for the 1986 OECD (NEA)/IAEA reports ''Nuclear Energy and its Fuel Cycle: Prospects to 2025''. In addition for this study, a mixed strategy case was computed using the averages of the Plutonium (Pu) burning LWR high, and the improved LWR low cases. It is understandable that such a long-term analysis cannot present hard facts, but it can show which variables may in fact influence the long-term supply-demand situation. It is hoped that results of this study will provide valuable information for planners in the uranium supply and demand fields. Periodical re-analyses with updated data bases will be needed from time to time

Quinoline-8-ol-immobilized Amberlite XAD-4: Synthesis, characterization, and uranyl ion uptake properties suitable for analytical applications

International Nuclear Information System (INIS)

Gladis, Mary J.; Prasada Rao, T.

2002-01-01

Amberlite XAD-4 has been functionalized by coupling it with 5-aminoquinoline-8-ol after acetylation. The resulting resin has been characterized by elemental analysis and IR spectra and has been used for preconcentrating uranyl ions prior to its determination by spectrophotometry. The optimum pH value for quantitative sorption is 4-6, and desorption can be achieved by using 5 mL of 1 mol L -1 HCl. The sorption capacity of the resin is 11.5 mmol g -1 . The effect of various cations and anions on the preconcentration of uranium in conjunction with the determination procedure has been studied and we have found that none of the ions interfere except thorium. The enrichment factor for preconcentration of uranium was found to be 200. Ten replicate determinations of 40 μg of uranium present in 1 L of sample gave a mean absorbance of 0.185 with a relative standard deviation of 2.64%. The detection limit corresponding to three times the standard deviation of the bank was found to be 2 μg L -1 . The validation of the developed preconcentration procedure was carried out by successfully analyzing standard marine sediment reference material. The uranyl content of sediment and soils is estimated by spectrophotometry after its preconcentration with the above chelating resin. (orig.)

Application of polyurethane foam as a sorbent for trace metal pre-concentration — A review

Science.gov (United States)

Lemos, V. A.; Santos, M. S.; Santos, E. S.; Santos, M. J. S.; dos Santos, W. N. L.; Souza, A. S.; de Jesus, D. S.; das Virgens, C. F.; Carvalho, M. S.; Oleszczuk, N.; Vale, M. G. R.; Welz, B.; Ferreira, S. L. C.

2007-01-01

The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.

Recovery of valuable products in liquid effluents from uranium and thorium pilot units

International Nuclear Information System (INIS)

Jardim, E.A.; Abrao, A.

1988-01-01

IPEN-CNEN/SP has being very active in refining yellowcake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, uranium tetra- and hexafluoride in a sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major waste to be worked is the refinate from the solvent extraction column where uranium and thorium are purified via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid and ammonium nitrate. Distilled nitric acid and the final sulfuric acid as residue are recycle. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium-free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximise the recycle and reuse of the abovementioned chemicals. (author) [pt

Determination and preconcentration of natural and radio-cesium from aqueous solution

International Nuclear Information System (INIS)

Gueclue, K.; Apak, R.; Tuetem, E.; Atun, G.

2004-01-01

A modified atomic emission spectrometric (AES) method to determine cesium(I), based on the measurement of emission intensity at 455.5 nm with a limit of quantitation (LOQ) of 5.5 mg/l and a linear range up to 100 mg/l is reported. In order to increase the sensitivity and lower the detection limits, potential sorbents were investigated for preconcentrating Cs from natural waters. Among the various ion-exchange materials synthesized, potassium hexanitrocobaltate (PHNCo) yielded the highest capacity for 137 Cs tagged Cs + solutions as measured by gamma-spectrometry with a HPGe detector, showing the potential of a cesium preconcentration sorbent. As an alternative to AES determination, the PHNCo sorbent may be used for Cs + collection from radiocesium tagged solutions and the retained activity in the dry solid exchanger be determined by gamma-spectrometry. (author)

Undiscovered Resource Modelling: Towards Applying a Systematic Approach to Uranium or How Much Uranium is Left and Where Might It Be Found?

International Nuclear Information System (INIS)

Fairclough, Martin; Katona, Laz

2014-01-01

Uranium Resource Modelling: Why do we want to plan for it? Purely from a supply-demand perspective: 1) Current supplies (at mid-range demand scenario) only enough until 2035 (likely to increase due to reactor shut down/stockpiling); 2) Not all uranium will be brought into production; 3) Long lead in times (particularly) for U mines; 4) Projections to 2060 (beyond IR) e.g IAEA TECDOC). From a socio-economic perspective: 1) Need for financial analysis; 2) Need for comparison with other land uses; 3) Need for comparison with other tracts of land; 4) Need for consideration of economic/environmental consequences of possible development; 5) Security of supply!!!

Preconcentration of uranium, thorium, zirconium, titanium, molybdenum and vanadium with oxine supported on microcrystalline naphthalene and their determinations by ICP-AES

International Nuclear Information System (INIS)

Kumar, Naveen; Kumar, Sanjay; Kumar, Vijay; Nandakishore, S.S.; Bangroo, P.N.

2013-01-01

As an effective technique for separation and preconcentration of trace elements, solid-liquid extraction with microcrystalline naphthalene has received great attention in recent years. The application of the adsorption of the metal complexes on microcrystalline naphthalene has greatly enhanced the utility of solid-liquid extraction in trace analysis. A survey of the literature revealed that single element detection techniques such as spectrophotometry, atomic absorption spectrometry, and polarography were mostly combined with this separation method. However, multi-element simultaneous detection techniques, like ICP-AES and ICP-MS were seldom used as the detectors in this solid-liquid extraction method. The aim of this work was to attempt to adopt the reagent oxine for the separation and subsequent determination of U, Th, Zr, Ti, Mo and V by ICP-AES, after adsorption of their oxinate complexes on microcrystalline naphthalene

Rapid, efficient and selective preconcentration of benzo[a]pyrene (BaP) by molecularly imprinted composite cartridge and HPLC

Energy Technology Data Exchange (ETDEWEB)

Çorman, Mehmet Emin, E-mail: mecorman@sinop.edu.tr [Hacettepe University, Department of Chemistry, Ankara (Turkey); Sinop University, Department of Bioengineering, Sinop (Turkey); Armutcu, Canan [Hacettepe University, Department of Chemistry, Ankara (Turkey); Uzun, Lokman, E-mail: lokman@hacettepe.edu.tr [Hacettepe University, Department of Chemistry, Ankara (Turkey); Denizli, Adil [Hacettepe University, Department of Chemistry, Ankara (Turkey)

2017-01-01

In this study, cryogel-based molecularly imprinted composite cartridges were designed for the rapid, efficient, and selective preconcentration of benzo[a]pyrene (BaP) from water samples. First, a BaP-imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-phenylalanine) composite cartridge was synthesized under semi-frozen conditions and characterized by scanning electron microscopy, elemental analysis, Fourier transform infrared spectroscopy, and swelling tests. After the optimization of preconcentration parameters, i.e., pH and initial BaP concentration, the selectivity and preconcentration efficiency, and reusability of these cartridges were also evaluated. In selectivity experiments, BaP imprinted composite cartridge exhibited binding capacities 3.09, 9.52, 8.87, and 8.77-fold higher than that of the non-imprinted composite cartridge in the presence of competitors, such as benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), indeno[1,2,3-cd]pyrene (IcdP), and 1-naphthol, respectively. The method detection limit (MDL), relative standard deviation (RSD) and preconcentration efficiency (PE) of the synthesized composite cartridge were calculated as 24.86 μg/L, 1.60%, and 349.6%, respectively. - Highlights: • Cryogel based molecularly imprinted composite cartridges as solid-phase extraction sorbents • Combination unique structural features of cryogels with MIP • An excellent ability to recognize the BaP molecule even if single-run contact • Rapid, efficient, selective and cost-friendly PAH preconcentration • Hydrophobic interactions via N-methacryloyl-(L)-phenylalanine.

Treatment of waste water from uranium ore preparation

International Nuclear Information System (INIS)

Klicka, V.; Mitas, J.; Vacek, J.

1976-01-01

An improved closed-loop process is described for treating waste water resulting from chemical extraction of uranium from ore. The water is evaporated to form a concentrated solution and is then subjected to crystallization of the least soluble salt component thereof via further evaporation, or cooling or simultaneous cooling and a partial vacuum. The crystallized component is then separated from the mother liquor, whereupon the latter is fed back after removal of residual uranium therefrom to the extraction installation to replace the acids used therein. Additionally, the pure condensate produced during evaporation of the waste waters is employed as a replacement for the fresh water employed in processing of the ore. 6 claims, 2 figures

Application of chitosan and its N-heterocyclic derivatives for preconcentration of noble metal ions and their determination using atomic absorption spectrometry.

Science.gov (United States)

Azarova, Yu A; Pestov, A V; Ustinov, A Yu; Bratskaya, S Yu

2015-12-10

Chitosan and its N-heterocyclic derivatives N-2-(2-pyridyl)ethylchitosan (2-PEC), N-2-(4-pyridyl) ethylchitosan (4-PEC), and N-(5-methyl-4-imidazolyl) methylchitosan (IMC) have been applied in group preconcentration of gold, platinum, and palladium for subsequent determination by atomic absorption spectroscopy (AAS) in solutions with high background concentrations of iron and sodium ions. It has been shown that the sorption mechanism, which was elucidated by XPS, significantly influences the sorption capacity of materials, the efficiency of metal ions elution after preconcentration, and, as a result, the accuracy of metal determination by AAS. We have shown that native chitosan was not suitable for preconcentration of Au(III), if the elution step was used as a part of the analysis scheme. The group preconcentration of Au(III), Pd(II), and Pt(IV) with subsequent quantitative elution using 0.1M HCl/1M thiourea solution was possible only on IMC and 4-PEC. Application of IMC for analysis of the national standard quartz ore sample proved that gold could be accurately determined after preconcentration/elution with the recovery above 80%. Copyright © 2015 Elsevier Ltd. All rights reserved.

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)

Sorption and Preconcentration of Lead on Silica Nanoparticles Modified with Resacetophenone

Directory of Open Access Journals (Sweden)

Anupreet Kaur

2009-01-01

Full Text Available The silica-resacetophenone (SiO2-RATP nanoparticles were used as a new sorbent for extraction of trace amounts of Pb(II by batch technique. Conditions of the analysis such as preconcentration factor, effect of pH, sample volume, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer SiO2-RATP was found to be 167.24 µ mol/g at optimum pH and the detection limit (3σ was 0.58 µg/L. The adsorption equilibrium of Pb(II on nanometer SiO2-RATP was achieved in 20 min. Adsorbed Pb(II was easily eluted with 5 mL of 0.5 M hydrochloric acid. The maximum preconcentration factor was 60. The method was applied for the determination of trace amounts of Pb(II in various natural water rivers.

Contribution to the study of nuclear fuel materials with a metallic uranium base

International Nuclear Information System (INIS)

Englander, M.

1957-11-01

In a power reactor destined to supply industrially recoverable thermal energy, the most economical source of heat still consists of natural metallic uranium. However, the nuclear fuel material, most often employed in the form of rods of 20 to 40 mm diameter, is subjected to a series of stresses which lead to irreversible distortions usually incompatible with the substructure of the reactor. As a result the fuel material must possess at the outset a certain number of qualities which must be determined. Investigations have therefore been carried out, first on the technological characters peculiar to each of the three allotropic phases of pure uranium metal, and on their interactions on the stabilisation of the material which consists of either cast uranium or uranium pile-treated in the γ phase. (author) [fr

Determination of crystalline texture in aluminium - uranium alloys by neutron diffraction

International Nuclear Information System (INIS)

Azevedo, A.M.V. de.

1978-01-01

Textures of hot-rolled aluminum-uranium alloys and of aluminum were determined by neutron diffraction. Sheets of alloys containing 8.0, 21.5 and 23.7 wt pct U, as well as pure aluminum, were obtained in a stepped rolling process, 15% reduction each step, 75% total reduction. During the rolling the temperature was 600 0 C. Alloys with low uranium contents are two phase systems in which an intermetallic compound UAl 4 , orthorhombic, is dispersed in a pure aluminum matrix. The addition of a few percent of Si in such alloys leads to the formation of UAl 3 , simple cubic, instead of UAl 4 . The Al -- 23.7 wt pct U alloy was prepared with 2,2 wt pct of Si. The results indicate that the texture of the matrix is more dependent on the uranium concentration than on the texture of the intermetallic phases. An improvement in the technique applied to texture measurements by using a sample fully bathed in the neutron beam is also presented. The method takes advantage of the low neutron absorption of the studied materials as well as of the neglibible variation in the multiple scattering which occurs in a conveniently shaped sample having a weakly developed texture. (Author) [pt

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)

Uranium extraction from colofanite via organic solvents

International Nuclear Information System (INIS)

Ribeiro, Valeria Aparecida Leitao

2007-01-01

This work describes the use of pure or combined extractants dissolved in organic solvents for quantitative uranium recovery from colofanite, a fluoroapatite ore, from Itataia, Santa Quiteria, Ceara, Brazil. This ore contains the highest brazilian uranium reserve. The metal is associated to phosphate species. The ore is digested with sulfuric acid (wet process), producing phosphoric acid, which is used for manufacturing of fertilizers and animal food. >From the acid leaching, some systems for uranium recovery were tested. Among them, PC88A (2-ethyl-hexyl phosphonic acid, mono-2-ethyl-hexyl ester) 40% vol. and DEHPA (di(2-ethyl-hexyl)phosphoric acid) 40% vol. in kerosene presented the highest values for the distribution coefficient (D) for uranium. When synergistic systems were employed, the best results were obtained for DEHPA 40%vol. + PC88A 40%vol. and DEHPA 40% vol. + TOPO (trioctylphosphine oxide) 5% vol. in kerosene. 15% wt/v sodium carbonate was the best medium for uranium stripping and separation from iron, the main interfering element. Uranium was precipitated as sodium diuranate by adding sodium hydroxide (5,0 mol L -1 ). Thorium in the raffinate was extracted by TOPO (0,1% vol.) in cyclohexane. The radioactivity level of the final aqueous waste is similar to natural background, according to CNEN-NE 6.05 Norm. After neutralization, the solid can be co-processed, according to the Directory 264 from the National Brazilian Environmental Council (CONAMA), whereas the treated effluent can be discarded according to the Directory 357 from CONAMA. (author)

Preparation of pure TiO2 sorption material

International Nuclear Information System (INIS)

Špendlíková, Irena; Raindl, Jakub; Němec, Mojmír

2013-01-01

Among the natural or anthropogenic radionuclides of very low concentrations nowadays measured in environmental samples, the radionuclide of 236 U has been recently included. In these ultra-trace analyses, the purity of sorption materials is very important and the traditional preparation procedures have to be optimized to minimize possible contamination. In the case of the determination of natural concentration of 236 U ( 236 U/ 238 U ∼ 10 -10 - 10 -14 ), the sample treatment procedure has to be modified in order to eliminate possible contamination from anthropogenic 236 U that may result even in more than ten thousand times higher 236 U/ 238 U ratios. Many inorganic and organic materials have been proposed for the extraction of uranium. However, only several of them are suitable for the uranium sorption from the solutions of low uranium concentration, but relatively high salt content, such as fresh water, sea water etc. At the same time they have to meet other limiting parameters such as fast kinetics, chemical stability, and low costs. Among the inorganic sorption materials, titanium dioxide has been studied for years with promising results. Titanium dioxides can be prepared via the hydrolysis of titanium compounds, either inorganic salts or organic derivatives, but their properties strongly depend on the preparation conditions. In classical procedures, titanium dioxides are prepared from commercial inorganic salts, such as sulphates or chlorides, or even from industrial intermediates of the titanium white production. Typically, the resulting titanium dioxides are contaminated with uranium already from the origin. Assuming that most organic compounds do not contain uranium and that it is possible to find 'uranium free' water, titanium dioxide free of uranium contamination could be prepared by the hydrolysis of organic titanium derivatives. The aim of this study was to find a suitable way of pure titanium dioxide preparation and to optimize the preparation

Nanoporous-carbon films for microsensor preconcentrators

Science.gov (United States)

Siegal, M. P.; Overmyer, D. L.; Kottenstette, R. J.; Tallant, D. R.; Yelton, W. G.

2002-05-01

Nanoporous-carbon (NPC) films are grown using physical processes such as low-power pulsed-laser deposition with attenuation of the ablated carbon species kinetic energy attained by using an inert background gas. With room-temperature growth and negligible residual stress, NPC can coat nearly any substrate to any desired thickness. Control of the deposition energetics yields precise morphology, density, and hence, porosity, with no discernable variation in chemical bonding. We produce NPC films 8 μm thick with density <0.2 g/cm3. The well-controlled porosity, i.e., available surface area, is demonstrated by using films with different thicknesses as a preconcentrator for a nerve-gas simulant.

Electrochemically induced chemical sensor properties in graphite screen-printed electrodes: The case of a chemical sensor for uranium

International Nuclear Information System (INIS)

Kostaki, Vasiliki T.; Florou, Ageliki B.; Prodromidis, Mamas I.

2011-01-01

Highlights: → Electrochemical treatment endows analytical characteristics to SPEs. → A sensitive chemical sensor for uranium is described. → Performance is due to a synergy between electrochemical treatment and ink's solvents. → The amount of the solvent controls the achievable sensitivity. - Abstract: We report for the first time on the possibility to develop chemical sensors based on electrochemically treated, non-modified, graphite screen-printed electrodes (SPEs). The applied galvanostatic treatment (5 μA for 6 min in 0.1 M H 2 SO 4 ) is demonstrated to be effective for the development of chemical sensors for the determination of uranium in aqueous solutions. A detailed study of the effect of various parameters related to the fabrication of SPEs on the performance of the resulting sensors along with some diagnostic experiments on conventional graphite electrodes showed that the inducible analytical characteristics are due to a synergy between electrochemical treatment and ink's solvents. Indeed, the amount of the latter onto the printed working layer controls the achievable sensitivity. The preconcentration of the analyte was performed in an electroless mode in an aqueous solutions of U(VI), pH 4.6, and then, the accumulated species was reduced by means of a differential pulse voltammetry scan in 0.1 M H 3 BO 3 , pH 3. Under selected experimental conditions, a linear calibration curve over the range 5 x 10 -9 to 10 -7 M U(VI) was constructed. The 3σ limit of detection at a preconcentration time of 30 min, and the relative standard deviation of the method were 4.5 x 10 -9 M U(VI) and >12% (n = 5, 5 x 10 -8 M U(VI)), respectively. The effect of potential interferences was also examined.

Development of pre-concentration procedure for the determination of Hg isotope ratios in seawater samples

International Nuclear Information System (INIS)

Štrok, Marko; Hintelmann, Holger; Dimock, Brian

2014-01-01

Highlights: • The method for the quantitative pre-concentration of Hg from seawater was developed. • First report of Hg isotope ratios in seawater is presented. • A unique mass independent 200 Hg isotope fractionation was observed. • This fractionation has unique potential to distinguish anthropogenic and natural Hg. - Abstract: Hg concentrations in seawater are usually too low to allow direct (without pre-concentration and removal of salt matrix) measurement of its isotope ratios with multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). Therefore, a new method for the pre-concentration of Hg from large volumes of seawater was developed. The final method allows for relatively fast (about 2.5 L h −1 ) and quantitative pre-concentration of Hg from seawater samples with an average Hg recovery of 98 ± 6%. Using this newly developed method we determined Hg isotope ratios in seawater. Reference seawater samples were compared to samples potentially impacted by anthropogenic activity. The results show negative mass dependent fractionation relative to the NIST 3133 Hg standard with δ 202 Hg values in the range from −0.50‰ to −1.50‰. In addition, positive mass independent fractionation of 200 Hg was observed for samples from reference sites, while impacted sites did not show significant Δ 200 Hg values. Although the influence of the impacted sediments is limited to the seawater and particulate matter in very close proximity to the sediment, this observation may raise the possibility of using Δ 200 Hg to distinguish between samples from impacted and reference sites

Development of a portable preconcentrator/ion mobility spectrometer system for the trace detection of narcotics

Energy Technology Data Exchange (ETDEWEB)

Parmeter, J.E.; Custer, C.A.

1997-08-01

This project was supported by LDRD funding for the development and preliminary testing of a portable narcotics detection system. The system developed combines a commercial trace detector known as an ion mobility spectrometer (IMS) with a preconcentrator originally designed by Department 5848 for the collection of explosives molecules. The detector and preconcentrator were combined along with all necessary accessories onto a push cart, thus yielding a fully portable detection unit. Preliminary testing with both explosives and narcotics molecules shown that the system is operational, and that it can successfully detect drugs as marijuana, methamphetamine (speed), and cocaine based on their characteristics IMS signatures.

Thermodynamics of the uranium (α, β and γ phases)-hydrogen system

International Nuclear Information System (INIS)

Northrup, C.J.M. Jr.

1975-01-01

Pressure-composition isotherms have been obtained for the uranium-hydrogen system over the pressure range from 0.1 to 680 atmospheres at temperatures ranging from 450 to 846 0 C. The hydride (delta) was formed from high purity uranium and pressure--temperature plots were obtained for the (U/sub alpha/, delta), (U/sub beta/, delta), (U/sub gamma/, delta) two phase regions. Results of the investigation indicate that in contrast to the work of Chevallier, Spitz, and Blum [Chevallier et al., Acad. Sci., 264: 96(1967)], the uranium-hydrogen system retains broad, flat, two phase plateaus on the pressure-composition isotherms to temperatures as high as 846 0 C. The effect of oxygen impurities is noted and it was found that the enthalpy of formation of the hydride from pure uranium was -28.9 kcal mol -1 . The three dimensional phase diagram for the system is discussed and the gas-liquid, gas-solid interface is given delineating the known phase boundaries. (U.S.)

Determination of scandium in acid mine drainage by ICP-OES with flow injection on-line preconcentration using oxidized multiwalled carbon nanotubes.

Science.gov (United States)

Jerez, Javier; Isaguirre, Andrea C; Bazán, Cristian; Martinez, Luis D; Cerutti, Soledad

2014-06-01

An on-line scandium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry associated with flow injection was studied. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with oxidized multiwalled carbon nanotubes, at pH 1.5. The retained analyte was removed from the minicolumn with 30% (v/v) nitric acid. A total enrichment factor of 225-fold was obtained within a preconcentration time of 300 s (for a 25 mL sample volume). The overall time required for preconcentration and elution of 25 mL of sample was about 6 min; the throughput was about 10 samples per hour. The value of the detection limit was 4 ng L(-1) and the precision for 10 replicate determinations at 100 ng L(-1) Sc level was 5% relative standard deviation, calculated from the peak heights obtained. The calibration graph using the preconcentration system was linear with a correlation coefficient of 0.9996 at levels near the detection limits up to at least 10 mg L(-1). After optimization, the method was successfully applied to the determination of Sc in an acid drainage from an abandoned mine located in the province of San Luis, Argentina. Copyright © 2014 Elsevier B.V. All rights reserved.

Preconcentration method using an activatable yield tracer for neutron activation analysis

International Nuclear Information System (INIS)

Tsukada, Masamichi; Yamamoto, Daijiro; Endo, Kazutoyo; Nakahara, Hiromichi

1991-01-01

Previously, the use of an enriched stable isotope as an activatable yield tracer in preconcentration steps has been tested by use of commercially available enriched 116 Cd and 156 Dy for biological standard reference materials. In the present work, this method has been further applied to the determination of lanthanoid contents in various kinds of samples: one coal fly-ash, three Japanese standard rocks, and eight standard soils. Samples were decomposed by alkali fusion in the preconcentration step. Thirteen elements were determined for coal fly-ash and soil samples, and 14 elements for rocks. The data obtained for coal fly-ash and standard rocks are compared with the data reported in literature. The data for soil samples have been newly determined in the present work. The ordinary instrumental neutron activation analysis and radiochemical neutron activation analysis were also performed to confirm the accuracy and usefulness of the present method. (author) 10 refs.; 4 tabs

Supply of enriched uranium for research reactors

International Nuclear Information System (INIS)

Mueller, H.

2004-01-01

Since the RERTR-Meeting in Newport/USA in 1990 recommended in several papers to the research reactor community to agree upon a worldwide unified technical specification for low enriched uranium (LEU) and high enriched uranium (HEU) in order to facilitate supplies of LEU and HEU to fabricators for acceptance and for fabrication of fresh fuel elements. This target for unified and simplified specification has only been partially reached due to different interests of the fabricators because they want to receive the uranium as pure as possible. As a result of various investigations, however, it became clear that both LEU and HEU received from the United States since the late fifties had different qualities which we have to deal with today due to the availability of stocks. We are now one step forward to know more precisely the properties of LEU and HEU we have received in the past. This uranium was never virgin and we have to cope with this situation. Therefore in my present paper I have concentrated on the documentation of analytical work performed on samples of LEU and HEU received in the past. I propose furthermore a frame of unified specifications for so-called virgin LEU and HEU including uranium from a Zero-experiment. In addition I am giving a recommendation for specifications of LEU obtained by blending of reprocessed HEU. Finally I am touching the question of secure supplies of fresh LEU. (author)

Comparative study of allotropic transformations of uranium and iron and of their structural consequences; Etude comparee des transformations allotropiques de l'uranium et du fer et de leurs consequences structurales

Energy Technology Data Exchange (ETDEWEB)

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

1957-06-15

The {alpha} {r_reversible} {beta} phase change in pure uranium occurs, as in the case of the {alpha} {r_reversible} {gamma} transformation in pure iron, according to a nucleation and growth process. The development of the nuclei during these transformations have been studied by controlling in a furnace presenting a temperature gradient, a slow and regular movement of the interface between the two phase. In those conditions, the number of {alpha} nuclei so formed, is limited and the development of big crystals, elongated in the direction of the temperature gradient, or eventually single crystals are obtained. The crystallographic orientation of these iron or uranium crystals, and their degree of perfection have been analysed. The dilatometric behaviour of the uranium single crystals were studied on a fraction of their crystallographic orientation. The expansion coefficients along the three principal axes of the orthorhombic {alpha} cell were measured. By passing through the {alpha} {r_reversible} {beta} or {beta} {r_reversible} {gamma} transformation points of uranium, it is possible to suppress all prior textures presented by the metal. Especially, water-quenching of uranium from the {beta} phase, gives a grain sufficiently small in size and without preferential orientation, so that a statistic compensation of the expansion anisotropy of each grain can be obtained. The stresses, created by fast cooling in the transformation range, produce a recrystallization of the metal during further annealing in the {alpha} phase. The volume change, which accompanies the {alpha} {r_reversible} {beta} transformation in uranium, and the {alpha} {r_reversible} {gamma} transformation in iron, creates, during the formation of the new phase nuclei and their subsequent growth, stresses which are important enough, to produce a real plastic deformation of the metal. The deformation characteristics, its structural consequences and the effect of the thermal cycling in the transformation

Conversion and Blending Facility highly enriched uranium to low enriched uranium as uranyl nitrate hexahydrate. Revision 1

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-07-05

This Conversion and Blending Facility (CBF) will have two missions: (1) convert HEU materials to pure HEU uranyl nitrate (UNH) and (2) blend pure HEU UNH with depleted and natural UNH to produce HEU UNH crystals. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. To the extent practical, the chemical and isotopic concentrations of blended LEU product will be held within the specifications required for LWR fuel. Such blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry. Otherwise, blended LEU Will be produced as a waste suitable for storage or disposal.

Recover of some rare earth elements from leach liquor of the Saghand uranium ore using combined precipitation and cation exchange methods

International Nuclear Information System (INIS)

Khanchi, A. R.; Rafati, H.; Rezvaniyanzadeh, M. R.

2008-01-01

In this research work, the recovery and separation of La(III), Ce(III), Sm(III), Dy(III) and Nd(III) from Saghand uranium ore have been studied by precipitation and ion-exchange chromatography methods using Dowex 50 W-X 8 cation exchanger. At first, some preliminary and preconcentration experiments such as comminution, sieve analysis, gravity table and electrostatic in preconcentration of lanthanides were performed. Then, acidic digesting and leaching procedure were used. The results of experiments showed that rare earth elements, along with interfering ions such as Al(III), Fe(III), Mg(II) and Mn(II) present in the leach liquor solution. The investigation of separation process by precipitation method revealed that precipitation and then fast separation using centrifugal technique had the best results in the elimination of interference elements. In order to separate the lanthanides and to obtain their elution curves, the chromatographic column containing Dowex 50 W-X 8 resin was employed. For efficient separation of lanthanides from interference elements the hydrochloric acid with concentration of two and six molar was used respectively. Recovery of lanthanides from the leach liquor solution was achieved more than 85%

Plasma emission spectroscopy (DCP) for rare earths determination in waters from Morro do Ferro (MG) Brazil, after chromatographic preconcentration

International Nuclear Information System (INIS)

Figueiredo, A.M.R. de.

1987-01-01

Rare earth determinations in surface and well waters from Morro do Ferro was studied using chemical preconcentration methods of the group and plasma emission spectroscopy excited by direct current are - DCP. A method that combines retention in alumina is HF medium with ion exchange for the preconcentration of the group was developed in semi micro scale. DCP determination, in the sequencial mode by using mixed standards containing, Y, La, Ce, Nd, Pr, Sm, Eu, Ga, Tb, Dy, Er, Yb and Al, principal concentrate componentes was studied by analysis of the profile of each spectral line. Principal cations, anions, ph and Eh were determined. Semi-micro techniques were developed for anions preconcentration and for determination of sulphate, phosphate and carbonate. (M.J.C.) [pt

Criticality calculations for a critical assembly, graphite moderate, using 20% enriched uranium

International Nuclear Information System (INIS)

Almeida Ferreira, A.C. de; Hukai, R.Y.

1975-01-01

The construction of a Zero Power Reactor (ZPR) at the Instituto de Energia Atomica in order to measure the neutron characteristics (parameters) of HTGR reactors is proposed. The necessary quantity fissile uranium for these measurements has been calculed. Criticality studies of graphite moderated critical assemblies containing thorium have been made and the critical mass of each of several typical commercial HTGR compositions has been calculated using computer codes HAMMER and CITATION. Assemblies investigated contained a central cylindrical core region, simulating a typical commercial HTGR composition, a uranium-graphite driver region and a outer pure graphite reflector region. It is concluded that a 10Kg inventory of fissile uranium will be required for a program of measurements utilizing each of the several calculated assemblies

Carbon nanotube enhanced membrane distillation for online preconcentration of trace pharmaceuticals in polar solvents.

Science.gov (United States)

Gethard, Ken; Mitra, Somenath

2011-06-21

Carbon nanotube enhanced membrane distillation (MD) is presented as a novel, online analytical preconcentration method for removing polar solvents thereby concentrating the analytes, making this technique an alternate to conventional thermal evaporation. In a carbon nanotube immobilized membrane (CNIM), the CNTs serve as sorbent sites and provide additional pathways for enhanced solvent vapor transport, thus enhancing preconcentration. Enrichment using CNIM doubled compared to membranes without CNTs, while the methanol flux and mass transfer coefficients increased by 61% and 519% respectively. The carbon nanotube enhanced MD process showed excellent precision (RSD of 3-5%), linearity, and the detection limits were in the range of 0.001 to 0.009 mg L(-1) by HPLC analysis.

Comparative study of allotropic transformations of uranium and iron and of their structural consequences; Etude comparee des transformations allotropiques de l'uranium et du fer et de leurs consequences structurales

Energy Technology Data Exchange (ETDEWEB)

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

1957-06-15

The {alpha} {r_reversible} {beta} phase change in pure uranium occurs, as in the case of the {alpha} {r_reversible} {gamma} transformation in pure iron, according to a nucleation and growth process. The development of the nuclei during these transformations have been studied by controlling in a furnace presenting a temperature gradient, a slow and regular movement of the interface between the two phase. In those conditions, the number of {alpha} nuclei so formed, is limited and the development of big crystals, elongated in the direction of the temperature gradient, or eventually single crystals are obtained. The crystallographic orientation of these iron or uranium crystals, and their degree of perfection have been analysed. The dilatometric behaviour of the uranium single crystals were studied on a fraction of their crystallographic orientation. The expansion coefficients along the three principal axes of the orthorhombic {alpha} cell were measured. By passing through the {alpha} {r_reversible} {beta} or {beta} {r_reversible} {gamma} transformation points of uranium, it is possible to suppress all prior textures presented by the metal. Especially, water-quenching of uranium from the {beta} phase, gives a grain sufficiently small in size and without preferential orientation, so that a statistic compensation of the expansion anisotropy of each grain can be obtained. The stresses, created by fast cooling in the transformation range, produce a recrystallization of the metal during further annealing in the {alpha} phase. The volume change, which accompanies the {alpha} {r_reversible} {beta} transformation in uranium, and the {alpha} {r_reversible} {gamma} transformation in iron, creates, during the formation of the new phase nuclei and their subsequent growth, stresses which are important enough, to produce a real plastic deformation of the metal. The deformation characteristics, its structural consequences and the effect of the thermal cycling in the transformation

Pre-concentration and determination of tartrazine dye from aqueous solutions using modified cellulose nanosponges.

Science.gov (United States)

Shiralipour, Roohollah; Larki, Arash

2017-01-01

In this study, a new absorbent based on cellulose nanosponges modified with methyltrioctylammonium chloride (aliquat 336) was prepared and used for pre-concentration, removal and determination of tartrazine dye, using UV-vis spectrophotometry. This adsorbent was fully characterized using various instrumental techniques such as SEM, FTIR and XRD spectra. The pre-concentration and removal procedures were studied in column and batch modes, respectively. The effects of parameters such as pH of the aqueous medium, methyltrioctylammounium chloride dose, adsorbent amount, desorbing conditions and interfering ions on the adsorption of tartrazine were investigated and optimized. The fitting experimental data with conventional isotherm models revealed that the adsorption followed the Brunauer-Emmett-Teller (BET) model and the maximum adsorption capacity for tartrazine was 180mg/g with modified nanosponges. Under the optimized conditions, the calibration curve was linear over the range of 2-300ng/mL and the limit of detection was 0.15ng/mL. The relative standard deviation (RSD) for 20 and 100ng/mL of tartrazine were 3.1% and 1.5%, respectively. The proposed method was applied for pre-concentration and determination of tartrazine dye in different water samples. Copyright © 2016 Elsevier Inc. All rights reserved.

Preconcentration of plutonium radionuclides from natural waters

International Nuclear Information System (INIS)

Wong, K.M.; Nioshkin, V.E.; Jokela, T.A.

1978-02-01

A large volume water sampler using manganese dioxide impregnated cartridges for the in situ separation of plutonium in sea water and ground water was studied. Plutonium concentrations obtained by this technique are compared with a radiochemical coprecipitation method. Consistent results were obtained between the two methods for water samples from the Pacific Ocean and Enewetak lagoon. Different results were noted from samples collected in the Enewetak reef and ground water stations. Using this preconcentration technique and the coprecipitation method it was shown that the physical-chemical characteristics of Pu in Enewetak reef and ground water are different from the lagoon and open ocean

Production of uranium-molybdenum particles by spark-erosion

International Nuclear Information System (INIS)

Cabanillas, E.D.; Lopez, M.; Pasqualini, E.E.; Cirilo Lombardo, D.J.

2004-01-01

With the spark-erosion method we have produced spheroidal particles of an uranium-molybdenum alloy using pure water as dielectric. The particles were characterized by optical metallography, scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. Mostly spherical particles of UO 2 with a distinctive size distribution with peaks centered at 70 and 10 μm were obtained. The particles have central inclusions of U and Mo compounds

Production of uranium-molybdenum particles by spark-erosion

Energy Technology Data Exchange (ETDEWEB)

Cabanillas, E.D. E-mail: cabanill@cnea.gov.ar; Lopez, M.; Pasqualini, E.E.; Cirilo Lombardo, D.J

2004-01-01

With the spark-erosion method we have produced spheroidal particles of an uranium-molybdenum alloy using pure water as dielectric. The particles were characterized by optical metallography, scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. Mostly spherical particles of UO{sub 2} with a distinctive size distribution with peaks centered at 70 and 10 {mu}m were obtained. The particles have central inclusions of U and Mo compounds.

Determination of gold in natural waters by neutron activation-#betta#-spectrometry after preconcentration on activated charcoal

International Nuclear Information System (INIS)

Hamilton, T.W.; Ellis, J.; Florence, T.M.

1983-01-01

A method for the determination of gold at very low levels in waters is presented. The method involves batchwise pre-concentration of gold from 1 l of water at pH 3-4 onto 0.1 g of activated charcoal by shaking for 5 min and subsequent treatment of the activated charcoal by instrumental neutron activation-#betta#-spectrometry. Activated charcoal quantitatively adsorbs ionic and colloidal gold from solutions prepared with distilled water and also from natural surface waters spiked and equilibrated with these two forms of gold. Three ion-exchange resins were evaluated for pre-concentration purposes; ionic gold removal was quantitative but colloidal gold removal was incomplete. Electrodeposition at a carbon fibre electrode gave similar results. The charcoal pre-concentration technique was tested on solutions containing 198 Au tracer and a total gold concentration of 1 μg l - 1 . The limit of detection of total gold (ionic and colloidal) for the carbon adsorption/neutron activation-#betta#-spectrometry procedure is 0.3 ng l - 1 . The method was used to determine gold in surface waters from auriferous regions. (Auth.)

Development of a technique of preparation of uranium screens for soft X Ray spectrography (1960)

International Nuclear Information System (INIS)

Bersuder, L. de

1961-01-01

The present work concerns the preparation of thin layers of pure uranium (thickness 100 to 1000 Angstrom) by thermal evaporation under vacuum. The protection of uranium against oxidation is obtained by using aluminium deposits under and above the uranium layer. The purity of the layers obtained is checked by electron diffraction and the necessary conditions to avoid oxidation and alloy formation during the formation of deposit are studied. Three methods for measuring the thickness are examined: by α particle counting, by weighing the condensed mass and by weighing the evaporated mass. The method using α particle counting turned to be the most accurate for low thickness layers. (author) [fr

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)

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.

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.

Supercritical fluid extraction of uranium for its purification from various yellow cake matrices

International Nuclear Information System (INIS)

Prabhat, Parimal; Rao, Ankita; Tomar, B.S.; Kumar, Pradeep

2016-01-01

Uranium is produced from different uranium ores as crude yellow cake of different chemical composition such as sodium diuranate (SDU), ammonium diuranate (ADU), magnesium diuranate (MDU), high temperature uranium peroxide (HTUP) etc. This depends on nature of ores and ore processing methods, availability of required facilities at processing site and other economic as well as environmental factors. These yellow cakes are further processed to produce pure uranium suitable for fuel fabrication facility by conventional solvent extraction process. Supercritical Fluid Extraction (SFE) is being developed as an alternate method for separation in nuclear fields due to its inherent potential to minimize liquid waste generation and process simplification. In present study, SFE of uranium from various yellowcake of different chemical composition has been carried out. Chemical parameter such as effect of TBP amount on SFE of uranium has been carried out and optimized at 2 ml for 200 mg SDU. Instrumental parameter such as temperature and pressure on SFE of uranium has been optimized at 323 K and 15.2 MPa. Extraction efficiency (%) achieved at optimized condition is 91.45 ± 0.2, 97.01 ± 0.75 and 96.72 ± 0.27 for SDU, MDU and HTUP respectively. Purity of uranium before SFE and after has been compared. Further studies is in progress for better understanding of chemical composition of matrix on SFE of uranium and improving purity of uranium separated from this route. (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

Argon/UF6 plasma exhaust gas reconstitution experiments using preheated fluorine and on-line diagnostics. [fissioning uranium plasma core reactor design

Science.gov (United States)

Roman, W. C.

1979-01-01

The feasibility of employing a flowing, high-temperature, pure fluorine/UF6 regeneration system to efficiently convert a large fraction of the effluent plasma exhaust back to pure UF6 was demonstrated. The custom built T.O.F. mass spectrometer sampling system permitted on-line measurements of the UF6 concentration at different locations in the exhaust system. Negligible amounts ( 100 ppm) of UF6 were detected in the axial bypass exhaust duct and the exhaust ducts downstream of the cryogenic trap system used to collect the UF6, thus verifying the overall system efficiency over a range of operating conditions. Use of a porous Monel duct as part of the exhaust duct system, including provision for injection of pure fluorine, provided a viable technique to eliminate uranium compound residue on the inside surface of the exhaust ducts. Typical uranium compound mass deposition per unit area of duct was 2 micron g/sq cm. This porous duct technique is directly applicable to future uranium compound transfer exhaust systems. Throughout these experiments, additional basic data on the corrosion aspects of hot, pressurized UF6/fluorine were also accumulated.

Characterization of uranium minerals from Chihuahua using synchrotron radiation

International Nuclear Information System (INIS)

Burciaga V, D. C.; Reyes C, M.; Reyes R, A.; Renteria V, M.; Esparza P, H.; Fuentes C, L.; Fuentes M, L; Silva S, M.; Herrera P, E.; Munoz, A.; Montero C, M. E.

2010-01-01

Uranium mineral deposits in the vicinity of Chihuahua City (northern Mexico) have motivated a multidisciplinary investigation due to their tech no-environmental importance. It provides a broad scope study of representative mineral samples extracted from the San Marcos deposit, located northwest of Chihuahua City. The zone of interest is the source of the Sacramento River, which runs at Chihuahua City. The high uranium content of the San Marcos deposit, which was formed by hydrothermal mineralization, has resulted in elevated levels of uranium in surface and ground water, fish, plants and sediments in this region. Mineral identification of the uranium-bearing phases was accomplished with a suite of techniques. Among these phases are those called meta tyuyamunite (Ca(UO 2 ) 2 (VO 4 ) 2 ·3-5 H 2 O) and becquerelite [Ca(UO 2 ) 6 O 4 (OH) 6 ·8(H 2 O)]. It was decided to study an almost pure meta tyuyamunite sample extracted from Pena Blanca, Chihuahua uranium ore and to synthesize the becquerelite, using a modified procedure from a published one. In the current work the crystal structure of meta tyuyamunite is presented, resolved by the Rietveld refinement. Both samples were studied by X-ray absorption fine structure at beamline 2-3, Stanford Synchrotron Radiation Light source. In the present work both the spectra and extended X-ray absorption fine structure parameters are presented. (Author)

An optimized procedure for preconcentration, determination and on-line recovery of palladium using highly selective diphenyldiketone-monothiosemicarbazone modified silica gel

International Nuclear Information System (INIS)

Sharma, R.K.; Pandey, Amit; Gulati, Shikha; Adholeya, Alok

2012-01-01

Highlights: ► Diphenyldiketone-monothiosemicarbazone modified silica gel. ► Highly selective, efficient and reusable chelating resin. ► Solid phase extraction system for on-line separation and preconcentration of Pd(II) ions. ► Application in catalytic converter and spiked tap water samples for on-line recovery of Pd(II) ions. - Abstract: A novel, highly selective, efficient and reusable chelating resin, diphenyldiketone-monothiosemicarbazone modified silica gel, was prepared and applied for the on-line separation and preconcentration of Pd(II) ions in catalytic converter and spiked tap water samples. Several parameters like effect of pH, sample volume, flow rate, type of eluent, and influence of various ionic interferences, etc. were evaluated for effective adsorption of palladium at trace levels. The resin was found to be highly selective for Pd(II) ions in the pH range 4–5 with a very high sorption capacity of 0.73 mmol/g and preconcentration factor of 335. The present environment friendly procedure has also been applied for large-scale extraction by employing the use of newly designed reactor in which on-line separation and preconcentration of Pd can be carried out easily and efficiently in short duration of time.

Automation in trace-element chemistry - Development of a fully automated on-line preconcentration device for trace analysis of heavy metals with atomic spectroscopy

International Nuclear Information System (INIS)

Michaelis, M.R.A.

1990-01-01

Scope of this work was the development of an automated system for trace element preconcentration to be used and integrated to analytic atomic spectroscopic methods like flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) or atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Based on the newly developed cellulose-based chelating cation exchangers ethylene-diamin-triacetic acid cellulose (EDTrA-Cellulose) and sulfonated-oxine cellulose a flexible, computer-controlled instrument for automation of preconcentration and/or of matrix separation of heavy metals is described. The most important properties of these materials are fast exchange kinetics, good selectivity against alkaline and alkaline earth elements, good flow characteristics and good stability of the material and the chelating functions against changes in pH-values of reagents necessary in the process. The combination of the preconcentration device for on-line determinations of Zn, Cd, Pb, Ni, Fe, Co, Mn, V, Cu, La, U, Th is described for FAAS and for ICP-AES with a simultaneous spectrometer. Signal enhancement factors of 70 are achieved from preconcentration of 10 ml and on-line determination with FAAS due to signal quantification in peak-height mode. For GFAAS and for sequential ICP methods for off-line preconcentration are given. The optimization and adaption of the interface to the different characteristics of the analytical instrumentation is emphasized. For evaluation and future developments with respect to determination and/or preconcentration of anionic species like As, Se, Sb etc. instrument modifications are proposed and a development software is described. (Author)

Experience of on-site disposal of production uranium-graphite nuclear reactor.

Science.gov (United States)

Pavliuk, Alexander O; Kotlyarevskiy, Sergey G; Bespala, Evgeny V; Zakharova, Elena V; Ermolaev, Vyacheslav M; Volkova, Anna G

2018-04-01

The paper reported the experience gained in the course of decommissioning EI-2 Production Uranium-Graphite Nuclear Reactor. EI-2 was a production Uranium-Graphite Nuclear Reactor located on the Production and Demonstration Center for Uranium-Graphite Reactors JSC (PDC UGR JSC) site of Seversk City, Tomsk Region, Russia. EI-2 commenced its operation in 1958, and was shut down on December 28, 1990, having operated for the period of 33 years all together. The extra pure grade graphite for the moderator, water for the coolant, and uranium metal for the fuel were used in the reactor. During the operation nitrogen gas was passed through the graphite stack of the reactor. In the process of decommissioning the PDC UGR JSC site the cavities in the reactor space were filled with clay-based materials. A specific composite barrier material based on clays and minerals of Siberian Region was developed for the purpose. Numerical modeling demonstrated the developed clay composite would make efficient geological barriers preventing release of radionuclides into the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Development of pre-concentration procedure for the determination of Hg isotope ratios in seawater samples.

Science.gov (United States)

Štrok, Marko; Hintelmann, Holger; Dimock, Brian

2014-12-03

Hg concentrations in seawater are usually too low to allow direct (without pre-concentration and removal of salt matrix) measurement of its isotope ratios with multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). Therefore, a new method for the pre-concentration of Hg from large volumes of seawater was developed. The final method allows for relatively fast (about 2.5Lh(-1)) and quantitative pre-concentration of Hg from seawater samples with an average Hg recovery of 98±6%. Using this newly developed method we determined Hg isotope ratios in seawater. Reference seawater samples were compared to samples potentially impacted by anthropogenic activity. The results show negative mass dependent fractionation relative to the NIST 3133 Hg standard with δ(202)Hg values in the range from -0.50‰ to -1.50‰. In addition, positive mass independent fractionation of (200)Hg was observed for samples from reference sites, while impacted sites did not show significant Δ(200)Hg values. Although the influence of the impacted sediments is limited to the seawater and particulate matter in very close proximity to the sediment, this observation may raise the possibility of using Δ(200)Hg to distinguish between samples from impacted and reference sites. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of mass-spectrometry and α-counting in analysis of uranium and plutonium isotopes in environmental samples

International Nuclear Information System (INIS)

Irleweck, K.; Pichlmayer, F.

1980-01-01

The determination of trace amounts of U and Pu isotopes is of interest in environmental and personal monitoring programmes. Commonly after preconcentration and separation of the radionuclides a proper sample is prepared electrolytically and the measurements are performed by alpha spectrometry. Some investigations on uranium isotopic abundances and on plutonium fallout deposition in soil have been carried out in this way. It is impossible to distinguish between the isotopes 239 Pu and 240 Pu by alpha spectrometry, however, because their α-energies are too close together. Such determinations can only be carried out by mass spectrometry. Specific Pu emissions, e.g. from nuclear production plants, can be discriminated from the global fallout level. Mass spectrometry is the more sensitive method for measuring long-lived nuclides compared with α-spectrometry. In the case of soil analysis, however, Pu detection is obstructed by the high natural uranium content, usually in the range 0.2 to 2.0 ppm which exceeds the trace amounts of plutonium by several orders of magnitude. This work describes a chemical procedure which separates U/Pu sufficiently for alpha spectrometry as well as for mass spectrometry, and compares results of environmental analysis applying both methods. (author)

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

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)

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

Graphene oxide sheets immobilized polystyrene for column preconcentration and sensitive determination of lead by flame atomic absorption spectrometry.

Science.gov (United States)

Islam, Aminul; Ahmad, Hilal; Zaidi, Noushi; Kumar, Suneel

2014-08-13

A novel solid-phase extractant was synthesized by coupling graphene oxide (GO) on chloromethylated polystyrene through an ethylenediamine spacer unit to develop a column method for the preconcentration/separation of lead prior to its determination by flame atomic absorption spectrometry. It was characterized by Fourier transform infrared spectroscopy, far-infrared spectroscopy, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, energy-dispersive spectrometry, and transmission electron microscopy. The abundant oxygen-containing surface functional groups form a strong complex with lead, resulting in higher sorption capacity (227.92 mg g(-1)) than other nanosorbents used for sorption studies of the column method. Using the column procedure here is an alternative to the direct use of GO, which restricts irreversible aggregation of GO and its escape into the ecosystem, making it an environmentally sustainable method. The column method was optimized by varying experimental variables such as pH, flow rate for sorption/desorption, and elution condition and was observed to exhibit a high preconcentration factor (400) with a low preconcentration limit (2.5 ppb) and a high degree of tolerance for matrix ions. The accuracy of the proposed method was verified by determining the Pb content in the standard reference materials and by recovery experiments. The method showed good precision with a relative standard deviation <5%. The proposed method was successfully applied for the determination of lead in tap water, electroplating wastewater, river water, and food samples after preconcentration.

A Micro-Preconcentrator Combined Olfactory Sensing System with a Micromechanical Cantilever Sensor for Detecting 2,4-Dinitrotoluene Gas Vapor

Directory of Open Access Journals (Sweden)

Myung-Sic Chae

2015-07-01

Full Text Available Preventing unexpected explosive attacks and tracing explosion-related molecules require the development of highly sensitive gas-vapor detection systems. For that purpose, a micromechanical cantilever-based olfactory sensing system including a sample preconcentrator was developed to detect 2,4-dinitrotoluene (2,4-DNT, which is a well-known by-product of the explosive molecule trinitrotoluene (TNT and exists in concentrations on the order of parts per billion in the atmosphere at room temperature. A peptide receptor (His-Pro-Asn-Phe-Ser-Lys-Tyr-Ile-Leu-His-Gln-Arg that has high binding affinity for 2,4-DNT was immobilized on the surface of the cantilever sensors to detect 2,4-DNT vapor for highly selective detection. A micro-preconcentrator (µPC was developed using Tenax-TA adsorbent to produce higher concentrations of 2,4-DNT molecules. The preconcentration was achieved via adsorption and thermal desorption phenomena occurring between target molecules and the adsorbent. The µPC directly integrated with a cantilever sensor and enhanced the sensitivity of the cantilever sensor as a pretreatment tool for the target vapor. The response was rapidly saturated within 5 min and sustained for more than 10 min when the concentrated vapor was introduced. By calculating preconcentration factor values, we verified that the cantilever sensor provides up to an eightfold improvement in sensing performance.

Amine-functionalized mesoporous polymer as potential sorbent for nickel preconcentration from electroplating wastewater.

Science.gov (United States)

Islam, Aminul; Zaidi, Noushi; Ahmad, Hilal; Kumar, Suneel

2015-05-01

In this study, mesoporous glycidyl methacrylate-divinylbenzene-based chelating resin was synthesized and grafted with diethylenetriamine through epoxy ring-opening reaction. The synthesized resin was characterized by elemental analysis, infrared spectroscopy, surface area and pore size analysis, scanning electron microscopy, energy-dispersive spectroscopy, and thermogravimetry. The resin was used for the first time as an effective sorbent for the preconcentration of nickel in electroplating wastewater samples. The analytical variables like pH, flow rate for sorption/desorption, and eluate selection were systematically investigated and optimized. The uniform and monolayer sorption behavior of resin for nickel was proved by an evident fit of the equilibrium data to a Langmuir isotherm model. Under optimized conditions, the resin was observed to show a good sorption capacity of 20.25 mg g(-1) and >96% recovery of nickel even in the presence of a large number of competitive matrix ions. Its ability to extract trace amount of nickel was exhibited by low preconcentration limit (5.9 μg L(-1)). The calibration curve was found to be linear (R(2) = 0.998) in the concentration range of 6.0-400.0 μg L(-1). Coefficient of variation of less than 5 for all the analysis indicated good reproducibility. The reliability was evaluated by the analysis of standard reference material (SRM) and recovery experiments. The applicability of the resin for the systematic preconcentration of nickel is substantiated by the analysis of electroplating wastewater and river water samples. Graphical abstract ᅟ.

Multielement determination of trace elements in seawater by inductively coupled plasma mass spectrometry after tandem preconcentration with cooperation of chelating resin adsorption and lanthanum coprecipitation

International Nuclear Information System (INIS)

Yabutani, Tomoki; Chiba, Koichi; Haraguchi, Hiroki

2001-01-01

A tandem preconcentration method, in which chelating resin adsorption and La coprecipitation were cooperatively employed for preconcentration, was developed as a pretreatment method for simultaneous multielement determination of trace elements in seawater by ICP-MS. First, the seawater sample (250 ml) was treated with a chelating resin for preconcentration of trace elements, and then trace elements with good recoveries were determined by ICP-MS. Trace elements with the chemical properties of oxoanion- and hydride-formation, which were poorly recovered in the chelating resin preconcentration, were further subjected to preconcentration by La coprecipitation. As a result, more than 30 elements could be determined in the concentration range from 9.6 μg L -1 for Mo to 0.00018 μg L -1 for Tm, when the present tandem method was applied to the analysis of open seawater standard reference material (NASS-4). Furthermore, the analytical results for open seawater reference materials were compared with those for coastal seawater reference material as well as for coastal seawater collected in the Ise Bay. It was found that the multielement data for trace elements in these seawater samples clearly showed different elemental distributions, reflecting the different marine environments. (author)

Contribution to the study of nuclear fuel materials with a metallic uranium base; Contribution a l'etude des materiaux combustibles nucleaires a base d'uranium metallique

Energy Technology Data Exchange (ETDEWEB)

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

1957-11-15

In a power reactor destined to supply industrially recoverable thermal energy, the most economical source of heat still consists of natural metallic uranium. However, the nuclear fuel material, most often employed in the form of rods of 20 to 40 mm diameter, is subjected to a series of stresses which lead to irreversible distortions usually incompatible with the substructure of the reactor. As a result the fuel material must possess at the outset a certain number of qualities which must be determined. Investigations have therefore been carried out, first on the technological characters peculiar to each of the three allotropic phases of pure uranium metal, and on their interactions on the stabilisation of the material which consists of either cast uranium or uranium pile-treated in the {gamma} phase. (author) [French] Dans un reacteur de puissance destine a fournir de l'energie thermique industriellement recuperable, la source de chaleur la plus economique reste constituee par de l'uranium metallique naturel. Or, le materiau combustible nucleaire, employe le plus souvent sous forme de barreaux de 20 a 40 mm de diametre, se trouve soumis a un ensemble de contraintes qui provoque des deformations irreversibles, le plus souvent incompatibles avec l'infrastructure du reacteur. Par consequent, le materiau combustible doit presenter a l'origine un certain nombre de qualites qu'il est necessaire de determiner. Aussi a-t-on d'abord etudie les caracteres technologiques propres a chacune des trois phases allotropiques de l'uranium-metal pur et leurs interactions sur la stabilisation du materiau constitue soit par de l'uranium coule, soit par de l'uranium traite en pile en phase {gamma}. (auteur)

A Very High Uranium Density Fission Mo Target Suitable for LEU Using atomization Technology

Energy Technology Data Exchange (ETDEWEB)

Kim, C. K.; Kim, K. H.; Lee, Y. S.; Ryu, H. J.; Woo, Y. M.; Jang, S. J.; Park, J. M.; Choi, S. J. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

Currently HEU minimization efforts in fission Mo production are underway in connection with the global threat reduction policy. In order to convert HEU to LEU for the fission Mo target, higher uranium density material could be applied. The uranium aluminide targets used world widely for commercial {sup 99}Mo production are limited to 3.0 g-U/cc in uranium density of the target meat. A consideration of high uranium density using the uranium metal particles dispersion plate target is taken into account. The irradiation burnup of the fission Mo target are as low as 8 at.% and the irradiation period is shorter than 7 days. Pure uranium material has higher thermal conductivity than uranium compounds or alloys. It is considered that the degradation by irradiation would be almost negligible. In this study, using the computer code of the PLATE developed by ANL the irradiation behavior was estimated. Some considerations were taken into account to improve the irradiation performance further. It has been known that some alloying elements of Si, Cr, Fe, and Mo are beneficial for reducing the swelling by grain refinement. In the RERTR program recently the interaction problem could be solved by adding a small amount of Si to the aluminum matrix phase. The fabrication process and the separation process for the proposed atomized uranium particles dispersion target were reviewed

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

Preconcentration of Co, Ni, Cd and Zn on naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent and flame atomic absorption determination

Directory of Open Access Journals (Sweden)

TAYYEBEH MADRAKIAN

2010-05-01

Full Text Available A preconcentration method was developed for the determination of trace amounts of Co, Ni, Cd and Zn by atomic absorption spectrometry. The method is based on the retention of the metal cations by naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent in a column. The adsorbed metals were then eluted from the column with hydrochloric acid and the Co, Ni, Cd and Zn were determined by flame atomic absorption spectrometry. The optimal extraction and elution conditions were studied. The effects of diverse ions on the preconcentration were also investigated. A preconcentration factor of 250 for Co(II, Ni(II and Zn(II, and 400 for Cd(II can easily be achieved. Calibration graphs were obtained and the detection limits of the method for Co(II, Ni(II, Cd(II and Zn(II were 0.51, 0.49, 0.17 and 0.10 ng mL-1, respectively. The relative standard deviations (RSD of 0.37–2.31 % for Co, 0.37–3.73 % for Ni, 2.20–2.40 % for Cd and 1.50–2.56 % for Zn were obtained. The method was also used for the simultaneous preconcentration of these elements and the method was successfully applied to their preconcentration and determination. The method was applied to the determination of Co, Ni, Cd and Zn in several real samples.

Extraction of uranium from sea water with the granular composite adsorbent by using the fixed bed

International Nuclear Information System (INIS)

Katoh, Shunsaku; Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Kitamura, Takao

1981-01-01

To clarify the technical problems existing in the extraction process of uranium from sea water, uranium was extracted from natural sea water, with the granulated C-Ti-OH composite adsorbent. The adsorption of uranium from sea water was carried out by using the fixed bed that had been designed in our laboratory. The uranium recovery from the sea water was 13.9% in the adsorption process of 56 d. The adsorbed uranium was eluted from the adsorbent with 0.5 N NaHCO 3 -0.5N Na 2 CO 3 soln. at 70 0 C. The elution recovery was 97.4% for 35 h. The uranium contained in the eluate was concentrated twenty times as much as in the anion exchange process, and then 100 times in the solvent extraction process with oxine-chloroform and TOA-kerosene. About 0.7 g of yellow cake was prepared from natural sea water, and it was identified to be pure 2UO 2 .NH 3 .3H 2 O by X-ray diffraction method and X-ray fluorometry. (author)

Application of a method to measure uranium enrichment without use of standards

International Nuclear Information System (INIS)

Saule, F.A.; Righetti, M.A.

1998-01-01

Full text: The determination of uranium enrichment in the many different stages present at a gaseous diffusion enrichment plant (diffusers, cisterns, deposits in pipes, drums with rests of process), or materials of deposit (plates of fuel elements not irradiated and recipients with uranium oxide), that have several geometries and physics properties of the containers, is very important for safeguards inspections. In this work is tested a non destructive analysis technique to determine the value of uranium enrichment of different samples with uranium materials without use of standards, to apply in safeguards inspections. It was used a hyper pure germanium detector with efficiency of 20% to obtain the gamma spectrum of the samples. In each spectrum, were used the net area values corresponding to four lines of U-235 (at 143, 163, 186 and 205 keV) and three lines of U-238 (258, 766 and 1001 keV); these values were analysed with two different methods. The comparison of the calculated and declared values showed a discrepancy of about 10%. (author) [es

Characterization of uranium minerals from Chihuahua using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Burciaga V, D. C.; Reyes C, M.; Reyes R, A.; Renteria V, M.; Esparza P, H.; Fuentes C, L.; Fuentes M, L; Silva S, M.; Herrera P, E.; Munoz, A.; Montero C, M. E. [Centro de Investigacion en Materiales Avanzados, S. C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua (Mexico)

2010-02-15

Uranium mineral deposits in the vicinity of Chihuahua City (northern Mexico) have motivated a multidisciplinary investigation due to their tech no-environmental importance. It provides a broad scope study of representative mineral samples extracted from the San Marcos deposit, located northwest of Chihuahua City. The zone of interest is the source of the Sacramento River, which runs at Chihuahua City. The high uranium content of the San Marcos deposit, which was formed by hydrothermal mineralization, has resulted in elevated levels of uranium in surface and ground water, fish, plants and sediments in this region. Mineral identification of the uranium-bearing phases was accomplished with a suite of techniques. Among these phases are those called meta tyuyamunite (Ca(UO{sub 2}){sub 2}(VO{sub 4}){sub 2{center_dot}}3-5 H{sub 2}O) and becquerelite [Ca(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6{center_dot}}8(H{sub 2}O)]. It was decided to study an almost pure meta tyuyamunite sample extracted from Pena Blanca, Chihuahua uranium ore and to synthesize the becquerelite, using a modified procedure from a published one. In the current work the crystal structure of meta tyuyamunite is presented, resolved by the Rietveld refinement. Both samples were studied by X-ray absorption fine structure at beamline 2-3, Stanford Synchrotron Radiation Light source. In the present work both the spectra and extended X-ray absorption fine structure parameters are presented. (Author)

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)

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)

Direct determination of uranium in human urine by Icp-SFMS; Determinacion directa de uranio en orina humana por ICP-SFMS

Energy Technology Data Exchange (ETDEWEB)

Hernandez M, H. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Yllera de Ll, A., E-mail: hector.hernandez520@gmail.com [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Departamento de Medio Ambiente, Av. Complutense 22, 28040 Madrid (Spain)

2013-10-15

The success of the measurement and the evaluation of the internal exposure are highly dependent of the effective capacities for the radiation measurement in biological samples (mainly urine and the feces). Usually, during the samples bioassay of human urine, a pre-concentration and purification of the radionuclides is carried out previously to the quantitative analysis. These stages, as the analysis time are the main source of uncertainty in the measurement process. In the uranium case, this is not necessary when are used mass spectrometry techniques, in particular, Mass Spectrometry of Magnetic Sector with Inductively Coupled Plasma (Icp-SFMS). This work presents the results obtained for the uranium analysis in samples of human urine during the participation in the inter-comparison exercises of the Association pour la Promotion de Controle de Qualite des Analyses de Biologie Medicale en Radiotoxicologie (PROCORAD) in the period 2010 and 2011. The analyses were realized directly in the diluted urine samples (dilution factor 1:20) in 5% of HNO{sub 3}. The obtained results, were normalized to the total urine sample (V = 0.5 L), these values coincide with the waited reference values of uranium in the urine sample. Additionally, were calculated the detection limits of {sup 235}U= 0.049 x 10{sup -3} μg L{sup -1} and {sup 238}U= 7.37 x 10{sup -3} μg L{sup -1}. (author)

Method and device for the dry preparation of ceramic uranium dioxide nuclear fuel wastes

International Nuclear Information System (INIS)

Pirk, H.; Roepenack, H.; Goeldner, U.

1977-01-01

Reprocessing of waste, resulting from the production of ceramic sintered bodies from uranium dioxide for use as nuclear fuel, in a dry process into very finely dispersed pure U 3 O 8 powder may be improved by applying vibrating screening during oxidation. An appropriate device is described. (UWI) [de

Recovery of valuable products in the raffinate of the uranium and thorium pilot-plant

International Nuclear Information System (INIS)

Jardim, E.A.; Abrao, A.

1988-11-01

IPEN-CNEN/SP has being very active in refining yellowcake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, tetra - and hexafluoride in a sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major to be worked is the raffinate from the solvent extraction colum where and thorium are purified via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid and ammonium nitrate. Distilled nitric acid and the final sulfuric acid as residue are recycle. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium - free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximize the recycle and reuse of the above mentioned chemicals. (author) [pt

Preconcentration and determination of heavy metals in water, sediment and biological samples

Directory of Open Access Journals (Sweden)

Shirkhanloo Hamid

2011-01-01

Full Text Available In this study, a simple, sensitive and accurate column preconcentration method was developed for the determination of Cd, Cu and Pb ions in river water, urine and sediment samples by flame atomic absorption spectrometry. The procedure is based on the retention of the analytes on a mixed cellulose ester membrane (MCEM column from buffered sample solutions and then their elution from the column with nitric acid. Several parameters, such as pH of the sample solution, volume of the sample and eluent and flow rates of the sample were evaluated. The effects of diverse ions on the preconcentration were also investigated. The recoveries were >95 %. The developed method was applied to the determination of trace metal ions in river water, urine and sediment samples, with satisfactory results. The 3δ detection limits for Cu, Pb and Cd were found to be 2, 3 and 0.2 μg dm−3, respectively. The presented procedure was successfully applied for determination of the copper, lead and cadmium contents in real samples, i.e., river water and biological samples.

Determination of arsenic in water samples by Total Reflection X-Ray Fluorescence using pre-concentration with alumina

Energy Technology Data Exchange (ETDEWEB)

Barros, Haydn [Laboratorio de Fisica Nuclear, Dpto. De Fisica, Universidad Simon Bolivar, Sartenejas, Baruta (Venezuela, Bolivarian Republic of); Marco Parra, Lue-Meru, E-mail: luemerumarco@yahoo.e [Universidad Centroccidental Lisandro Alvarado, Dpto. Quimica y Suelos, Decanato de Agronomia, Tarabana, Cabudare, Edo.Lara (Venezuela, Bolivarian Republic of); Bennun, Leonardo [Universidad de Concepcion, Concepcion (Chile); Greaves, Eduardo D. [Laboratorio de Fisica Nuclear, Dpto. De Fisica, Universidad Simon Bolivar, Sartenejas, Baruta (Venezuela, Bolivarian Republic of)

2010-06-15

The determination of arsenic in water samples requires techniques of high sensitivity. Total Reflection X-Ray Fluorescence (TXRF) allows the determination but a prior separation and pre-concentration procedure is necessary. Alumina is a suitable substrate for the selective separation of the analytes. A method for separation and pre-concentration in alumina, followed by direct analysis of the alumina is evaluated. Quantification was performed using the Al-K{alpha} and Co-K{alpha} lines as internal standard in samples prepared on an alumina matrix, and compared to a calibration with aqueous standards. Artificial water samples of As (III) and As (V) were analyzed after the treatment. Fifty milliliters of the sample at ppb concentration levels were mixed with 10 mg of alumina. The pH, time and temperature were controlled. The alumina was separated from the slurry by centrifugation, washed with de-ionized water and analyzed directly on the sample holder. A pre-concentration factor of 100 was found, with detection limit of 0.7 {mu}gL{sup -1}. The percentage of recovery was 98% for As (III) and 95% for As (V) demonstrating the suitability of the procedure.

Determination of arsenic in water samples by Total Reflection X-Ray Fluorescence using pre-concentration with alumina

International Nuclear Information System (INIS)

Barros, Haydn; Marco Parra, Lue-Meru; Bennun, Leonardo; Greaves, Eduardo D.

2010-01-01

The determination of arsenic in water samples requires techniques of high sensitivity. Total Reflection X-Ray Fluorescence (TXRF) allows the determination but a prior separation and pre-concentration procedure is necessary. Alumina is a suitable substrate for the selective separation of the analytes. A method for separation and pre-concentration in alumina, followed by direct analysis of the alumina is evaluated. Quantification was performed using the Al-Kα and Co-Kα lines as internal standard in samples prepared on an alumina matrix, and compared to a calibration with aqueous standards. Artificial water samples of As (III) and As (V) were analyzed after the treatment. Fifty milliliters of the sample at ppb concentration levels were mixed with 10 mg of alumina. The pH, time and temperature were controlled. The alumina was separated from the slurry by centrifugation, washed with de-ionized water and analyzed directly on the sample holder. A pre-concentration factor of 100 was found, with detection limit of 0.7 μgL -1 . The percentage of recovery was 98% for As (III) and 95% for As (V) demonstrating the suitability of the procedure.

Determination of trace amounts of lead by chelating ion exchange and on-line preconcentration in flow-injection atomic absorption spectrometry

International Nuclear Information System (INIS)

Purohit, Rajesh; Devi, Surekha

1992-01-01

Resins synthesized from quinolin-8-ol and resorcinol or hydro-quinone, with furfuraldehyde, formaldehyde or benzaldehyde as cross-linking agent, were used for the preconcentration of nanogram amounts of lead. The rate of exchange and activation energy of lead exchange were calculated. Column separations of lead-copper and lead-zinc did not show any cross-contamination. A continuous flow manifold using resin microcolumns was developed for the preconcentration and determination of lead. (author). 24 refs.; 5 figs.; 3 tabs

Dislocations and radiation damage in α-uranium

International Nuclear Information System (INIS)

Leteurtre, J.

1969-01-01

Dislocations in α-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in α-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [fr

In situ carbonate leaching and recovery of uranium from ore deposits

International Nuclear Information System (INIS)

Hunkin, G.G.; Fife, T.P.; Stano, J.R.

1979-01-01

Uranium is leached from redox roll ore deposits by selective in-situ leaching with a solution of pH 7.4 to 9 (preferably 7.5 to 8.5) containing from about 0.5 to 5g/l of NH 4 HCO 3 and from about 0.1 to 3g/l of peroxide (preferably aqueous H 2 O 2 ), and sufficient NH 3 to maintain the desired pH. The leach solution is then withdrawn from the ore deposit and contacted with a strong base anion exchange material to strip the uranium from the leach solution. The uranium is eluted from the anion exchange material by an aqueous eluant, and the uranium is recovered from the eluate by first acidifying it and then treating it with ammonia to produce a precipitate of relatively pure ammonium diuranate. The content of the three components in the stripped leach solution is adjusted, and then the leach solution is recirculated through the ore deposit. After the uranium ore is removed to the extent economically practicable, the leach solution is replaced with an aqueous reducing solution which when passed into the ore deposit precipitates and renders insoluble any uranium and elements such as vanadium, molybdenum, and selenium. This process produces above ground a very low volume of impurities and waste solutions requiring disposal and does not cause material contamination of the underground deposit or any aquifer associated with the deposit

Analytical strategies for uranium determination in natural water and industrial effluents samples

International Nuclear Information System (INIS)

Santos, Juracir Silva

2011-01-01

waste generation. A linear response was observed from 5.0 to 150.0 μg L -1 , with a detection limit, RSD, and sampling rate estimated as 1.3 μg L -1 (99.7% confidence level), 0.7% (n = 20), and 40 determinations per hour, respectively. The consumption of arsenazo 111 was reduced in 1250-fold in comparison to a procedure with preconcentration in solid phase. The accuracy of the methods was confirmed by analysis of two laboratory reference materials. In addition, an effluent sample was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the observed recovery was satisfactory. The developed methods were applied to the determination of uranium in river, well and drinking water and industrial effluent collected from uranium-producing mine in Caetite city, Brazil. The results for uranium in drinking water samples from Caetite city were below the limit of quantification of methods, except for well water (17.0 +- 0.8 mg L -1 ) and a river water collected near of the mine (9.6 +- 0.8 mg L -1 ). (author)

Concentration of uranium on TiO-PAN and NaTiO-PAN composite absorbers

International Nuclear Information System (INIS)

Motl, Alois; Sebesta, Ferdinand; John, Jan; Spendlikova, Irena; Nemec, Mojmir

2013-01-01

Inorganic ion exchangers have been extensively tested for use in separation and concentration of uranium from Surface water. Except for separation of uranium from uranium -Contaminated waste water (e.g. waste water from mining and milling of uranium, Waste from nuclear fuel reprocessing) their main area of application has been foreseen to be their use for extraction of uranium from sea water which could partially cover future needs of uranium. Another perspective area of application is pre-concentration of uranium from natural waters followed by uranium determination via various specialized techniques such as TRLFS or AMS. Possibilities of uranium extraction from sea water have been subject of several international conferences (e.g. Topical meetings on the Recovery of Uranium from Seawater in 1980's, ACS National Meetings 2012 etc.) and are critically evaluated in a review by Bitte or recently by Kim. In the Czech Republic uranium-selective inorganic ion exchangers might be applied for treatment of various wastes from uranium industry, namely underground Water, uranium milling over-balance water, or acid waste water from underground uranium leaching and also like in other countries for determination of uranium isotopic composition focusing on anthropogenic and natural 236 U content. Among the best performing inorganic ion exchangers for the above listed purposes hydrated titanium dioxide (abbreviated as TiO) and sodium titanate (abbreviated as NaTiO) can be listed. Properties of TiO and NaTiO were reviewed by Lehto. From the point of view of ion-exchange, properties of hydrated titanium oxide and sodium titanate are very similar. The main disadvantage of these ion exchangers for industrial-scale application is their insufficient mechanical stability. To improve this property, the sorption materials can be embedded into a binding matrix. Modified polyacrylonitrile (PAN) has been proposed at the Czech Technical University in Prague as a universal binding matrix for

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)

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.

A Study on the Fabrication of Uranium-Cadmium Alloy and its Distillation Behavior

International Nuclear Information System (INIS)

Kim, Ji Yong; Ahn, Do Hee; Kim, Kwang Rag; Paek, Seung Woo; Kim, Si Hyung

2010-01-01

The pyrometallurgical nuclear fuel recycle process, called pyroprocessing, has been known as a promising nuclear fuel recycling technology. Pyroprocessing technology is crucial to advanced nuclear systems due to increased nuclear proliferation resistance and economic efficiency. The basic concept of pyroprocessing is group actinide recovery, which enhances the nuclear proliferation resistance significantly. One of the key steps in pyroprocessing is 'electrowinning' which recovers group actinides with lanthanide from the spent nuclear fuels. In this study, a vertical cadmium distiller was manufactured. The evaporation rate of pure cadmium in vertical cadmium distiller varied from 12.3 to 40.8 g/cm 2 /h within a temperature range of 773 ∼ 923 K and pressure below 0.01 torr. Uranium - cadmium alloy was fabricated by electrolysis using liquid cadmium cathode in a high purity argon atmosphere glove box. The distillation behavior of pure cadmium and cadmium in uranium - cadmium alloy was investigated. The distillation behavior of cadmium from this study could be used to develop an actinide recovery process from a liquid cadmium cathode in a cadmium distiller

A Study on the Fabrication of Uranium-Cadmium Alloy and its Distillation Behavior

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji Yong [University of Science and Technology, Daejeon (Korea, Republic of); Ahn, Do Hee; Kim, Kwang Rag; Paek, Seung Woo; Kim, Si Hyung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-12-15

The pyrometallurgical nuclear fuel recycle process, called pyroprocessing, has been known as a promising nuclear fuel recycling technology. Pyroprocessing technology is crucial to advanced nuclear systems due to increased nuclear proliferation resistance and economic efficiency. The basic concept of pyroprocessing is group actinide recovery, which enhances the nuclear proliferation resistance significantly. One of the key steps in pyroprocessing is 'electrowinning' which recovers group actinides with lanthanide from the spent nuclear fuels. In this study, a vertical cadmium distiller was manufactured. The evaporation rate of pure cadmium in vertical cadmium distiller varied from 12.3 to 40.8 g/cm{sup 2}/h within a temperature range of 773 {approx} 923 K and pressure below 0.01 torr. Uranium - cadmium alloy was fabricated by electrolysis using liquid cadmium cathode in a high purity argon atmosphere glove box. The distillation behavior of pure cadmium and cadmium in uranium - cadmium alloy was investigated. The distillation behavior of cadmium from this study could be used to develop an actinide recovery process from a liquid cadmium cathode in a cadmium distiller.

Progress in metal ion separation and preconcentration: an overview

International Nuclear Information System (INIS)

Bond, A. H.

1998-01-01

A brief historical perspective covering the most mature chemically-based metal ion separation methods is presented, as is a summary of the recommendations made in the 1987 National Research Council (NRC) report entitled ''Separation and Purification: Critical Needs and Opportunities''. A review of Progress in Metal Ion Separation and Preconcentration shows that advances are occurring in each area of need cited by the NRC. Following an explanation of the objectives and general organization of this book, the contents of each chapter are briefly summarized and some future research opportunities in metal ion separations are presented

Determination of technetium-99, thorium-230 and uranium-234 in soils by inductively coupled plasma mass spectrometry using flow injection preconcentration

International Nuclear Information System (INIS)

Hollenbach, Mark; Grohs, James; Mamich, Stephen; Kroft, Marilyn; Denoyer, E.R.

1994-01-01

A new method is described for the determination of 99 Tc, 230 Th, and 234 U at ultra-trace levels in soils. The method used flow injection (FI) for on-line preconcentration of 99 Tc, 230 Th and 234 U prior to detection using inductively coupled plasma mass spectrometry (ICP-MS). The FI-ICP-MS method results in greater sensitivity and freedom from interferences compared with direct aspiration into an ICP mass spectrometer. Detection limits are improved by approximately a factor of 10. The FI-ICP-MS method is also faster, less labour intensive and generates less laboratory waste than traditional radiochemical methods. The accuracy of the method was tested for 99 Tc by comparison to liquid scintillation counting and for 230 Th and 234 U by analysis of a US Department of Energy reference soil. Detection limits in the soil for 99 Tc, 230 Th and 234 U were 11 mBq g -1 (0.02 ng g -1 ), 3.7 mBq g -1 (0.005 ng g -1 ) and 0.74 mBq g -1 (0.003 ng g -1 ), respectively. Sample preparation, analysis protocol, and method validation are described. (Author)

On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma-optical emission spectrometry

International Nuclear Information System (INIS)

Ortega, Claudia; Cerutti, Soledad; Silva, Maria F.; Olsina, Roberto A.; Martinez, Luis D.

2003-01-01

An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L -1 nitric acid at a flow rate of 1.5 mL min -1 , directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 μg L -1 . The precision for 10 replicate determinations at the 2.0 μg L -1 Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 μg L -1 . The method was successfully applied to the determination of dysprosium in urine. (orig.)

A study on neutron activation analysis for the determination of the contents of impurities in reactor materials

International Nuclear Information System (INIS)

Kim, N.B.

1983-01-01

In determining the contents of impurity elements in reactor materials using neutron activation analysis, methods for preconcentration and radiochemical separtion have been studied. Before applying neutron irradiation, impurities in uranium dioxide have been preconcentrated by an anion exchange separtion method and boron impurity has been preconcentrated by a cation exchange separation method or an ashing method. After neutron irradiation the radiochemical separation method for the determination of 27 elements is based on a group separation using ion-exchange resin and material exchanger. The method has imployed mineral acid or organic mixture of the acid, excluding hydrofluoric acid, as the media and common glass wares as the apparatus. This separation method was applied to the reactor materials such as aluminum, steel, graphite and uranium dioxide. The single comparator method was used for determining the content of each element separated radiochemically and analytical results gave the statistical and systematic errors of less than 10% and 6.1%, respectively. A prompt gamma-ray measurement method has been used for determining the content of preconcentrated boron and the analytical results gave the statistical and systematic errors of 5.4% and 3.3%, respectively. (Author)

Electrokinetic sample preconcentration and hydrodynamic sample injection for microchip electrophoresis using a pneumatic microvalve.

Science.gov (United States)

Cong, Yongzheng; Katipamula, Shanta; Geng, Tao; Prost, Spencer A; Tang, Keqi; Kelly, Ryan T

2016-02-01

A microfluidic platform was developed to perform online electrokinetic sample preconcentration and rapid hydrodynamic sample injection for zone electrophoresis using a single microvalve. The polydimethylsiloxane microchip comprises a separation channel, a side channel for sample introduction, and a control channel which is used as a pneumatic microvalve aligned at the intersection of the two flow channels. The closed microvalve, created by multilayer soft lithography, serves as a nanochannel preconcentrator under an applied electric potential, enabling current to pass through while preventing bulk flow. Once analytes are concentrated, the valve is briefly opened and the stacked sample is pressure injected into the separation channel for electrophoretic separation. Fluorescently labeled peptides were enriched by a factor of ∼450 in 230 s. This method enables both rapid analyte concentration and controlled injection volume for high sensitivity, high-resolution CE. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

International Uranium Resources Evaluation Project (IUREP) national favourability studies: Iran

International Nuclear Information System (INIS)

1977-12-01

Iran is on the southern flank of the Alpine-Himalayan mountain system and has within its extensive boundaries rocks ranging from crystalline metamorphics and igneous rocks of Precambrian age to sediments of Tertiary - Pleistocene age, some of which could be considered as potentially favourable for uranium deposits. The search for uranium started about 1959 and in the following years some 40 radioactive anomalies and a small number of uranium occurrences were identified. In 1977 the Atomic Energy Organization of Iran greatly expanded its exploration activities and contracted for 895,000 line kilometres to be flown by three contractors in an aerial spectrometric survey designed to cover almost the two fifths of the whole country. The follow-up of this survey will continue for several years. Purely on the basis of its size (1,648,004 km 2 ), its several favourable host rock areas, its location on the flank of the Alpine-Himalayan system and the relatively small amount of systematic exploration coverage completed to date the Speculative Potential could be placed in the 50,000 - 100,000 tonnes category. (author)

Contribution to the study of the uranium-hydrogen system; Contribution a l'etude du systeme uranium-hydrogene

Energy Technology Data Exchange (ETDEWEB)

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

1965-01-01

Previous work on uranium-hydrogen system is reviewed. The U-H{sub 2}-UH{sub n} equilibrium is then investigated at pressures below one atmosphere, i.e. at temperatures lower than 430 deg. C. The hydride obtained at equilibrium is deficient in hydrogen (UH{sub n<3}), the hydrogen deficit increasing as the temperature rises. Thermodynamic functions for the formation of non-stoichiometric hydride and of one hydrogen vacancy are derived from pressure composition isotherms, in U-H phase diagram is proposed. The hydrogenation of U-UC alloys is also examined at pressures below one atmosphere with regard to the equilibrium: (free U + UC) - H{sub 2}-UH{sub n}. The equilibrium conditions are found different from that observed for pure uranium. (author) [French] Une etude bibliographique du systeme uranium-hydrogene est exposee. L'equilibre U-H{sub 2}-UH{sub n} est ensuite etudie sous des pressions inferieures a une atmosphere, soit aux temperatures inferieures a environ 430 degs. C. L'hydrure obtenu a l'equilibre est deficitaire en hydrogene - UH{sub n<3} - et d'autant plus que la temperature s'eleve. Les grandeurs thermodynamiques relatives a la formation et a la saturation de l'hydrure, ainsi qu'a la formation d'une lacune d'hydrogene sont deduites des pressions d'equilibre. Un modele de diagramme de phases U-H est propose. L'hyduration des alliages U-UC est etudiee egalement sous des pressions inferieures a l'atmosphere, au point de vue de l'equilibre (U libre + UC) - H{sub 2}-UH{sub n}. Les conditions d'equilibre sont trouvees differentes de celles observees sur l'uranium pur. (auteur)

Determination of trace elements by neutron activation analysis using dinonylnaphtalene sulfonic acid as a preconcentrating agent

International Nuclear Information System (INIS)

Yang, M.H.; Chen, P.Y.; Tseng, C.L.; Yeh, S.J.; Weng, P.S.

1977-01-01

Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate the interfering elements such as Na, K, Cl and Br, which normally exist in the natural aqueous systems. Experiments were performed by extracting the ions in the aqueous medium with HD in n-hexane and subsequently backextracted into a minimal volume of acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration technique has been successfully applied to the determination by neutron activation analysis of trace elements in natural water and biological materials. Both short-lived nuclides (Mg, Al, Ca, Mn) and long-lived nuclides (Sm, Eu, Zn, La, Cr, Sc, Fe, Co) in the ppb-level concentrations were determined. (T.G.)

Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

Energy Technology Data Exchange (ETDEWEB)

Leduc, Jennifer; Mathur, Sanjay [Institute of Inorganic Chemistry, University of Cologne (Germany); Pacold, Joseph I.; Shuh, David K. [Chemical Sciences Division, The Glenn T. Seaborg Center, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China)

2018-01-17

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO{sub 2} nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

International Nuclear Information System (INIS)

Leduc, Jennifer; Mathur, Sanjay; Pacold, Joseph I.; Shuh, David K.; Dong, Chung-Li

2018-01-01

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO 2 nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preconcentration, Separation and Determination of lead(II) with Methyl Thymol Blue Adsorbed on Activated Carbon Using Flame Atomic Absorption Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali A.; Ghaderi, Ali R. [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

2008-02-15

An on-line system for preconcentration and separation of lead(II) is presented. The method is based on the complex formation of Pb(II) with adsorbed Methyl thymol blue on activated carbon. The conditions of preparing the solid phase reagent and of quantitative recovery of Pb(II) from diluted solutions, such as acidity of aqueous phase, solid phase capacity, and flow variables were studied as well as effect of potential interfering ions. After preconcentration step, the metal ions are eluted automatically by 5 ml of 0.5 M HNO{sub 3} solution and the lead ions content was determined by flame atomic absorption spectrometry. Under the optimum conditions, the lead ions in aqueous samples were separated and preconcentrated about 1000-fold by the column. The detection limit was 0.001 μg mL{sup -1}. Lead has been determined in river and tap water samples, with recovery of 98 to 102%.

Eldorado Port Hope refinery - uranium production (1933-1951)

International Nuclear Information System (INIS)

Arsenault, J.E.

2008-01-01

continued to produce uranium products for export and for use in the fledgling Canadian nuclear research program at Chalk River, Ontario, which led ultimately to the CANada Deuterium Uranium (CANDU) family of nuclear power reactors so familiar today. Until 1951 uranium was produced using purely chemical methods, then new processes (including resin ion exchange and solvent extraction) came to dominate because of their relatively lower cost and high recovery. This article reviews the Port Hope refinery operation from 1933 to 1951, particularly during the peak uranium production years of 1943 and 1944. (author)

Eldorado Port Hope refinery - uranium production (1933-1951)

Energy Technology Data Exchange (ETDEWEB)

Arsenault, J.E

2008-03-15

refinery continued to produce uranium products for export and for use in the fledgling Canadian nuclear research program at Chalk River, Ontario, which led ultimately to the CANada Deuterium Uranium (CANDU) family of nuclear power reactors so familiar today. Until 1951 uranium was produced using purely chemical methods, then new processes (including resin ion exchange and solvent extraction) came to dominate because of their relatively lower cost and high recovery. This article reviews the Port Hope refinery operation from 1933 to 1951, particularly during the peak uranium production years of 1943 and 1944. (author)

Liquid electrode plasma-optical emission spectrometry combined with solid-phase preconcentration for on-site analysis of lead.

Science.gov (United States)

Barua, Suman; Rahman, Ismail M M; Alam, Iftakharul; Miyaguchi, Maho; Sawai, Hikaru; Maki, Teruya; Hasegawa, Hiroshi

2017-08-15

A relatively rapid and precise method is presented for the determination of lead in aqueous matrix. The method consists of analyte quantitation using the liquid electrode plasma-optical emission spectrometry (LEP-OES) coupled with selective separation/preconcentration by solid-phase extraction (SPE). The impact of operating variables on the retention of lead in SPEs such as pH, flow rate of the sample solution; type, volume, flow rate of the eluent; and matrix effects were investigated. Selective SPE-separation/preconcentration minimized the interfering effect due to manganese in solution and limitations in lead-detection in low-concentration samples by LEP-OES. The LEP-OES operating parameters such as the electrical conductivity of sample solution; applied voltage; on-time, off-time, pulse count for applied voltage; number of measurements; and matrix effects have also been optimized to obtain a distinct peak for the lead at λ max =405.8nm. The limit of detection (3σ) and the limit of quantification (10σ) for lead determination using the technique were found as 1.9 and 6.5ng mL -1 , respectively. The precision, as relative standard deviation, was lower than 5% at 0.1μg mL -1 Pb, and the preconcentration factor was found to be 187. The proposed method was applied to the analysis of lead contents in the natural aqueous matrix (recovery rate:>95%). The method accuracy was verified using certified reference material of wastewaters: SPS-WW1 and ERM-CA713. The results from LEP-OES were in good agreement with inductively coupled plasma optical emission spectrometry measurements of the same samples. The application of the method is rapid (≤5min, without preconcentration) with a reliable detection limit at trace levels. Copyright © 2017 Elsevier B.V. All rights reserved.

The application of radiotracer technique for preconcentration neutron activation analysis

International Nuclear Information System (INIS)

Wang Xiaolin; Chen Yinliang; Sun Ying; Fu Yibei

1995-01-01

The application of radiotracer technique for preconcentration neutron activation analysis (Pre-NAA) are studied and the method for determination of chemical yield of Pre-NAA is developed. This method has been applied to determination of gold, iridium and rhenium in steel and rock samples and the contents of noble metal are in the range of 1-20 ng·g -1 (sample). In addition, the accuracy difference caused by determination of chemical yield between RNAA and Pre-NAA are also discussed

Study of the Reactions Controlling the Mobility of Uranium in Ground and Surface Water Systems in Contact with Apatite

International Nuclear Information System (INIS)

Taffet, M

2004-01-01

hydroxyapatite can sorb over 7.53 X 10 -6 moles or 1.8 mg of uranium in agreement with calculations based on phosphate and calcium oxide sites on the unit cell. Our work is significant because small masses of hydroxyapatite can sorb appreciable masses of uranium quickly over a wide range of chemistries. Preliminary work with ground water containing 260 ppb of uranium and cow bone char indicates that its sorptive capacity is appreciable less than pure hydroxyapatite. Pure crystalline hydroxyapatite sequestered 2.9 mg of uranium per m 2 as opposed to 0.083 mg of uranium sequestered per m 2 of cow bone char, or 27% versus 3.5% by surface area, respectively. Extended x-ray adsorption fine structure (EXAFS) spectroscopy defined mono- and bidentate sorption of uranium to phosphate and calcium oxide groups on the hydroxyapatite surface. The EXAFS data indicate that up to several thousand parts U per million parts hydroxyapatite, surface complexation, and not precipitation, is the predominant process. Above this uranium: hydroxyapatite mass ratio, precipitation of meta-autunite (H 2 (UO 2 )2(PO 4 ) 2 x 10H 2 0) dominates the sequestration process

Determination of mercury in seawater by total reflection x-ray fluorescence spectrometry after an electrochemical preconcentration method

International Nuclear Information System (INIS)

Ritschel, A.; Chinea Cano, E.; Wobrauschek, P.; Kuntner, C.; Durakbasa, M.N.

2000-01-01

A new combined method of electrodeposition of trace elements on metallic plates with subsequent total-reflection x-ray fluorescence spectrometry (TXRF) is proposed for the determination of trace metals in natural waters. The elements of interest are electroplated on highly polished niobium discs which are used as sample carriers for the TXRF measurement. The electrochemical preconcentration is performed in a flow cell under a controlled working electrode potential. The preconcentration step involves only very little manipulation which minimizes the risk of contamination of the sample. The method was investigated by analyzing inorganic mercury in sea water. A detection limit of 7 ngl -1 could be achieved for mercury in a 40 ml sea water sample. (author)

Synthesis, characterization and application of ion imprinted poly(vinylimidazole for zinc ion extraction/preconcentration with faas determination

Directory of Open Access Journals (Sweden)

Queila O. dos Santos

2014-01-01

Full Text Available In this paper, we describe the synthesis of an ion imprinted polymer (IIP by homogeneous polymerization and its use in solid-phase to extract and preconcentrate zinc ions. Under optimal conditions (pH 5.0, preconcentration flow rate of 12.0 mL min-1, and eluted with 1.0 mol L-1 HNO3 this procedure allows the determination of zinc with an enrichment factor of 10.2, and with limits of detection and quantification of 1.5 and 5.0 µg L-1, respectively. The accuracy of our results was confirmed by analysis of tap water and certified reference materials: NIST 1570a (Spinach leaves and NIST 1515 (Apple leaves.

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)

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.)

Salt evaporation behaviors of uranium deposits from an electrorefiner

International Nuclear Information System (INIS)

Sung Bin Park; Dong Wook Cho; Gyu Hwan Oh; Sung Chan Hwang; Young Ho Kang; Hansoo Lee; Eung Ho Kim; Seong-Won Park; Jong Hyeon Lee

2010-01-01

From an electrorefining process, uranium deposits were recovered at the solid cathode of an electrorefining system. The uranium deposits from the electrorefiner contained about 30-40 wt% salts. In order to recover pure uranium and transform it into metal ingots, these salts have to be removed. A salt distiller was adapted for a salt evaporation. A batch operation for the salt removal was carried out by a heating and a vacuum evaporation. The operational conditions were a 700-1,000 deg C hold temperature and less than a 1 Torr under Argon atmosphere, respectively. The behaviors of the salt evaporations were investigated by focusing on the effects of the pressure and the holding temperature for the salt distillation. The removal efficiencies of the salts were obtained with regard to the operational conditions. The experimental results of the salt evaporations were evaluated by using the Hertz-Langmuir relation. The effective evaporation coefficients of this relation were obtained with regards to the vacuum pressures and the hold temperatures. The higher the vacuum pressure and the higher the holding temperature were, the higher the removal efficiencies of the salts were. (author)

Preconcentration of Zn2+ and Cu2+ ions from food and vegetable samples using modified activated carbon.

Science.gov (United States)

Ghaedi, M; Tavallali, H; Montazerozohori, M; Zahedi, E; Amirineko, M; Khodadoust, S; Karimipour, G

2012-11-01

In this work, two N/S-containing chelating agents 2-(4-methoxybenzylideneamino)thiophenol (2-4-MBAT) and 2-(4-chlorobenzylideneamino) benzenethiol (2-4-CBABT) were synthesized as new sorbents and were used for preconcentration of Zn(2+) and Cu(2+) ions in food and vegetable samples. In the proposed procedure, the trace amount of Zn(2+) and Cu(2+) ions from 250 mL of sample solution at pH = 5.0 was preconcentrated by 1 g of activated carbon (AC) loaded with 15 mg of 2-4-MBAT and 2-4-CBABT separately. The breakthrough volumes (maximum sample volume that their metal ions quantitatively can be enriched) for solid-phase extraction (SPE) procedure based on the AC modified with 2-4-MBAT and 2-4-CBABT were 800 and 750 mL, respectively. The sorbed Zn(2+) and Cu(2+) ions were efficiently eluted by 8 mL of 4 mol L(-1) HNO(3) and preconcentration factor of 112.5 and 93.7 and experimental enhancement factor of 30 and 35 ions were obtained for Zn(2+) and Cu(2+), respectively. The application of this enrichment procedure allowed the extraction of trace metal ions with recoveries exceeding of 90%.

Sample preconcentration utilizing nanofractures generated by junction gap breakdown assisted by self-assembled monolayer of gold nanoparticles.

Directory of Open Access Journals (Sweden)

Chun-Ping Jen

Full Text Available The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×10(4 for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA and anti-BSA was carried out to demonstrate the applicability of the proposed chip.

Rapid and sensitive detection of malachite green in aquaculture water by electrochemical preconcentration and surface-enhanced Raman scattering.

Science.gov (United States)

Xu, Kai-Xuan; Guo, Mei-Hong; Huang, Yu-Ping; Li, Xiao-Dong; Sun, Jian-Jun

2018-04-01

A highly sensitive and rapid method of in-situ surface-enhanced Raman spectroscopy (SERS) combining with electrochemical preconcentration (EP) in detecting malachite green (MG) in aquaculture water was established. Ag nanoparticles (AgNPs) were synthesized and spread onto the surface of gold electrodes after centrifuging to produce SERS-active substrates. After optimizing the pH values, preconcentration potentials and times, in-situ EP-SERS detection was carried out. A sensitive and rapid analysis of the low-concentration MG was accomplished within 200s and the limit of detection was 2.4 × 10 -16 M. Copyright © 2017 Elsevier B.V. All rights reserved.

Preconcentration of natural protactinium from thorium concentrate with subsequent determination using Gamma (γ) spectrometry

International Nuclear Information System (INIS)

Raja, Naine; Swain, Kallola; Kayasth, S.R.; Pathassarathy, R.; Mathur, P.K.; Anil Kumar, S.

1999-01-01

A simple and efficient method has been developed to preconcentrate natural protactinium ( 231 Pa) from large size of thorium concentrate (5.0-100.0g) on Dowex 1 X 8 in acid medium. Gamma spectrometry, a powerful determination technique, has been used for quantitative determination of protactinium

Nickel (II) Preconcentration and Speciation Analysis During Transport from Aqueous Solutions Using a Hollow-fiber Permeation Liquid Membrane (HFPLM) Device.

Science.gov (United States)

Bautista-Flores, Ana Nelly; De San Miguel, Eduardo Rodríguez; Gyves, Josefina de; Jönsson, Jan Åke

2011-08-18

Nickel (II) preconcentration and speciation analysis using a hollow fiber supported liquid membrane (HFSLM) device was studied. A counterflow of protons coupled to complexation with formate provided the driving force of the process, while Kelex 100 was employed as carrier. The influence of variables related to module configuration (acceptor pH and carrier concentration) and to the sample properties (donor pH) on the preconcentration factor, E, was simultaneously studied and optimized using a 3 factor Doehlert matrix response surface methodology. The effect of metal concentration was studied as well. Preconcentration factors as high as 4240 were observed  depending on the values of the different variables. The effects of the presence of inorganic anions (NO2-, SO42-, Cl-, NO3-, CO32-, CN-) and dissolved organic matter (DOM) in the form of humic acids were additionally considered in order to carry out a speciation analysis study. Nickel preconcentration was observed to be independent of both effects, except when cyanide was present in the donor phase. A characterization of the transport regime was performed through the analysis of the dependence of E on the temperature. E increases with the increase in temperature according to the equation E(K) = -8617.3 + 30.5T with an activation energy of 56.7 kJ mol-1 suggesting a kinetic-controlled regime. Sample depletion ranged from 12 to 1.2% depending on the volume of the donor phase (100 to 1000 mL, respectively).

Nickel (II Preconcentration and Speciation Analysis During Transport from Aqueous Solutions Using a Hollow-fiber Permeation Liquid Membrane (HFPLM Device

Directory of Open Access Journals (Sweden)

Jan Åke Jönsson

2011-08-01

Full Text Available Nickel (II preconcentration and speciation analysis using a hollow fiber supported liquid membrane (HFSLM device was studied. A counterflow of protons coupled to complexation with formate provided the driving force of the process, while Kelex 100 was employed as carrier. The influence of variables related to module configuration (acceptor pH and carrier concentration and to the sample properties (donor pH on the preconcentration factor, E, was simultaneously studied and optimized using a 3 factor Doehlert matrix response surface methodology. The effect of metal concentration was studied as well. Preconcentration factors as high as 4240 were observed  depending on the values of the different variables. The effects of the presence of inorganic anions (NO2-, SO42-, Cl-, NO3-, CO32-, CN- and dissolved organic matter (DOM in the form of humic acids were additionally considered in order to carry out a speciation analysis study. Nickel preconcentration was observed to be independent of both effects, except when cyanide was present in the donor phase. A characterization of the transport regime was performed through the analysis of the dependence of E on the temperature. E increases with the increase in temperature according to the equation E(K = -8617.3 + 30.5T with an activation energy of 56.7 kJ mol-1 suggesting a kinetic-controlled regime. Sample depletion ranged from 12 to 1.2% depending on the volume of the donor phase (100 to 1000 mL, respectively.

Notes on uranium geochemistry applied to the study of intergranitic deposits and their envelope

International Nuclear Information System (INIS)

Carrat, H.G.

1975-01-01

Research on the natural state of uranium, either in the form of traces in the crystal structure or in intergranitic pitchblende deposits is presented. In the former case the methods considered are those relative to post-magma development, a phenomenon having well established connections with the crystallization of uranite type ores. This can be interpreted as a preconcentration if certain genetics concepts are adopted. New aspects of these relationships will then be reported. In the latter case two kinds of research will be presented, corresponding to two types of hypotheses. First, the laying down of pitchblendes by supergenesis is based on the easy degradation of uraninite under meteoric conditions, which will be considered in the geochemical and paleogeographical contexts. Second, the hydrothermal nature of pitchblendes will find strong support in experimental studies on the fluid inclusions of the ore, its matrix and its immediate envelope and from considerations on depth tectonics [fr

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.)

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)

Selective extraction of metals from acidic uranium(VI) solutions using neo-tridecano-hydroxamic acid

International Nuclear Information System (INIS)

Bardoncelli, F.; Grossi, G.

1975-01-01

According to this invention neo-alkyl-hydroxamic acids are employed as ion-exchanging agents in processes for liquid-liquid extraction with the aim of separating, purifying dissolved metals and of converting a metal salt solution into a solution of a salt of the same metal but with different anion. In particular it is an objective of this invention to provide a method whereby a molecular pure uranium solution is obtained by selective extraction from a uranium solution delivered by irradiated fuel reprocessing plants and containing plutonium, fission products and other unwanted metals, in which method neo-tridecane-hydroxamic acid is employed as ion exchanger. (Official Gazette)

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)

Phthalocyaninato complexes of thorium, protactinium and uranium

International Nuclear Information System (INIS)

Beck, O.F.

1985-01-01

For the preparation of Bis(phthalocyaninato)-actinoid(IV) complexes, AnPc 2 , a new optimizing synthesis procedure was developed, with which it was possible to prepare spectrally pure, that is, H 2 Pc-free, ThPc 2 , UPc 2 and the isostructurally similar 231 PaPc 2 .PaPc 2 . This was verified with the help of electron spectra, which were compared to preparations which were synthesized in another manner. The corresponding perfluorinated compounds were also produced for thorium and uranium by use of tetrafluorophthalic acid nitrile instead of phthalic acid nitrile as initial product. Electron and infrared spectra show the typical bands of the non-substituted complexes. By the attempt to produce a mono(phthalocyaninato)-thorium complex with the use of ThI 4 as initial material a pyridine-extracted pure ThPcI 2 (py) 2 was obtained with a typical mono(phthalocyaninato) complex electron spectrum, an extremely moisture sensitive compound which in water or acids decomposes and produces H 2 Pc. (orig./RB) [de

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

Progress in metal ion separation and preconcentration : an overview.

Energy Technology Data Exchange (ETDEWEB)

Bond, A. H.

1998-05-19

A brief historical perspective covering the most mature chemically-based metal ion separation methods is presented, as is a summary of the recommendations made in the 1987 National Research Council (NRC) report entitled ''Separation and Purification: Critical Needs and Opportunities''. A review of Progress in Metal Ion Separation and Preconcentration shows that advances are occurring in each area of need cited by the NRC. Following an explanation of the objectives and general organization of this book, the contents of each chapter are briefly summarized and some future research opportunities in metal ion separations are presented.

Contribution to the study of nuclear fuel materials with a metallic uranium base; Contribution a l'etude des materiaux combustibles nucleaires a base d'uranium metallique

Energy Technology Data Exchange (ETDEWEB)

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

1957-11-15

In a power reactor destined to supply industrially recoverable thermal energy, the most economical source of heat still consists of natural metallic uranium. However, the nuclear fuel material, most often employed in the form of rods of 20 to 40 mm diameter, is subjected to a series of stresses which lead to irreversible distortions usually incompatible with the substructure of the reactor. As a result the fuel material must possess at the outset a certain number of qualities which must be determined. Investigations have therefore been carried out, first on the technological characters peculiar to each of the three allotropic phases of pure uranium metal, and on their interactions on the stabilisation of the material which consists of either cast uranium or uranium pile-treated in the {gamma} phase. (author) [French] Dans un reacteur de puissance destine a fournir de l'energie thermique industriellement recuperable, la source de chaleur la plus economique reste constituee par de l'uranium metallique naturel. Or, le materiau combustible nucleaire, employe le plus souvent sous forme de barreaux de 20 a 40 mm de diametre, se trouve soumis a un ensemble de contraintes qui provoque des deformations irreversibles, le plus souvent incompatibles avec l'infrastructure du reacteur. Par consequent, le materiau combustible doit presenter a l'origine un certain nombre de qualites qu'il est necessaire de determiner. Aussi a-t-on d'abord etudie les caracteres technologiques propres a chacune des trois phases allotropiques de l'uranium-metal pur et leurs interactions sur la stabilisation du materiau constitue soit par de l'uranium coule, soit par de l'uranium traite en pile en phase {gamma}. (auteur)

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)

A comparative study between transport and criticality safety indexes for fissile uranium nuclearly pure

Energy Technology Data Exchange (ETDEWEB)

Moraes da Silva, T. de; Sordi, G.M.A.A. [Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN (Brazil)]. e-mail: tmsilva@ipen.br

2006-07-01

The international and national standards determine that during the transport of radioactive materials the package to be sent should be identified by labels of risks specifying content, activity and the transport index. The result of the monitoring of the package to 1 meter identifies the transport index, TI, which represents the dose rate to 1 meter of this. The transport index is, by definition, a number that represents a gamma radiation that crosses the superficial layer the radioactive material of the package to 1 meter of distance. For the fissile radioactive material that is the one in which a neutron causes the division of the atom, the international standards specify criticality safety index CSI, which is related with the safe mass of the fissile element. In this work it was determined the respective safe mass for each considered enrichment for the compounds of uranium oxides UO{sub 2}, U{sub 3}O{sub 8} and U{sub 3}Si{sub 2}. In the study of CSI it was observed that the value 50 of the expression 50/N being N the number of packages be transported in subcriticality conditions it represents a fifth part of the safe mass of the element uranium or 9% of the smallest mass critical for a transport not under exclusive use. As conclusion of the accomplished study was observed that the transport index starting from 7% of enrichment doesn't present contribution and that criticality safety index is always greater than the transport index. Therefore what the standards demand to specify, the largest value between both indexes, was clearly identified in this study as being the criticality safety index. (Author)

Preparing activated carbon from charcoal and investigation of the selective uranium adsorption

International Nuclear Information System (INIS)

Kuetahyali, C.; Eral, M.

2001-01-01

Preconcentration and separation procedures based on adsorption phenomena are important in nuclear and especially radiation chemistry, industry, medicine and daily life. Adsorption of uranium onto various solids is important from purification, environmental and radioactive waste disposal points of view . The treatment of aqueous nuclear waste solutions containing soluble metal ions requires concentration of the metal ions into smaller volume followed by recovery or secure disposal. For this purpose, many processes are being utilized such as precipitation, ion-exchange, solvent extraction and adsorption on solids etc. Interest in the adsorption of metal ions for recovery purposes has increased manyfold in recent years, because of its simplicity, selectivity and efficiency . The main advantage of adsorption is the separation of trace amount of elements from large volumes of solutions. In recent years, several studies have been made to recover radionuclides by adsorption using natural and synthetic adsorbents. Adsorption on charcoal is one of the most efficient techniques used in water treatment processes for the removal of organics and micropollutants from wastes and drinking waters. Adsorption processes have long been used in the removal of color, odor, and organic pollution. These processes are usually based on the use of activated carbon . Activated carbon consists mainly of carbon and is produced from every carbonaceous material. Activated carbon characterized by its high surface area and its wide distribution of porosity. The textural properties (surface area and porosity) of activated carbons play an important role in determining the capacity of the material in adsorption from aqueous solution. Chemistry of the surface is also important . Generally, activated carbons are mainly microporous, but in addition to micropores they contain meso- and macropores, which are very important in facilitating acces of the adsorbate molecules to the interior of carbon particles

Recent technical progress in the French uranium industry

International Nuclear Information System (INIS)

Huet, H.

1961-01-01

This paper reviews the present-day uranium production situation in France. The various stages of the treatment the concentrates receive, leading to the final production of the metal, are described briefly: dissolution, purification by extraction with a mixture of tributyl phosphate and white spirit, precipitation with ammonia, drying and calcination of the trioxide, reduction with hydrogen, cracked ammonia or preferably pure ammonia gas, fluorination with anhydrous hydrofluoric acid, and production of the metal by the calcium thermite process. Recent work of an original nature is discussed in greater detail. (author) [fr

Ultratrace determination of lead by hydride generation in-atomizer trapping atomic absorption spectrometry: Optimization of plumbane generation and analyte preconcentration in a quartz trap-and-atomizer device

Energy Technology Data Exchange (ETDEWEB)

Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz

2012-05-15

A compact trap-and-atomizer device and a preconcentration procedure based on hydride trapping in excess of oxygen over hydrogen in the collection step, both constructed and developed previously in our laboratory, were employed to optimize plumbane trapping in this device and to develop a routine method for ultratrace lead determination subsequently. The inherent advantage of this preconcentration approach is that 100% preconcentration efficiency for lead is reached in this device which has never been reported before using quartz or metal traps. Plumbane is completely retained in the trap-and-atomizer device at 290 Degree-Sign C in oxygen-rich atmosphere and trapped species are subsequently volatilized at 830 Degree-Sign C in hydrogen-rich atmosphere. Effect of relevant experimental parameters on plumbane trapping and lead volatilization are discussed, and possible trapping mechanisms are hypothesized. Plumbane trapping in the trap-and-atomizer device can be routinely used for lead determination at ultratrace levels reaching a detection limit of 0.21 ng ml{sup -1} Pb (30 s preconcentration, sample volume 2 ml). Further improvement of the detection limit is feasible by reducing the blank signal and increasing the trapping time. - Highlights: Black-Right-Pointing-Pointer In-atomizer trapping HG-AAS was optimized for Pb. Black-Right-Pointing-Pointer A compact quartz trap-and-atomizer device was employed. Black-Right-Pointing-Pointer Generation, preconcentration and atomization steps were investigated in detail. Black-Right-Pointing-Pointer 100% preconcentration efficiency for lead was reached. Black-Right-Pointing-Pointer Routine analytical method was developed for Pb determination (LOD of 0.2 ng ml{sup -1} Pb).

An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry.

Science.gov (United States)

Minami, Tomoharu; Konagaya, Wataru; Zheng, Linjie; Takano, Shotaro; Sasaki, Masanobu; Murata, Rena; Nakaguchi, Yuzuru; Sohrin, Yoshiki

2015-01-07

A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al.). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1M HNO3, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

Some applications of x-ray fluorescence spectrography to the determination of uranium and thorium

International Nuclear Information System (INIS)

Jones, R.W.

1959-04-01

Several methods for the determination of uranium and thorium by X-ray fluorescence spectrography are described. In pure solutions the sensitivity for these elements is 5-10 ppm. For solutions containing gross concentrations of impurities, strontium is added as an internal standard. Precision and accuracy of the determinations are about 1% when working in the optimum concentration range. (author)

Separation of uranium, molibdenum and vanadium in sulphuric solutions by extraction with alamine 336

International Nuclear Information System (INIS)

Floh, B.

1976-01-01

Alamine 336 - varsol - sulphuric acid-water system used for uranium, molibdenum and vanadium extraction, from sulphuric leaching and an appropriate plan for fractioning those elements are investigated. The behavior of cited elements in pure solutions followed by interaction that occurs in both bynary and tertiary systems are studied. Distribution coefficient is regarded for measuring such effects [pt

Improvements made in the methods of purifying uranium compounds and in the production of uranium metal at the Bouchet plant; Ameliorations apportees aux procedes de purification des composes d'uranium et a la fabrication de l'uranium metal a l'usine du Bouchet

Energy Technology Data Exchange (ETDEWEB)

Decrop, J; Delange, M; Holder, J; Huet, H; Sauteron, J; Vertes, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

We intend to chart the development of the techniques used at the Bouchet plant since the First International Conference held in Geneva in 1955. During that Conference, the methods adopted at that time were described by B. GOLDSCHMIDT and P. VERTES. Generally speaking, the development since that time has been governed by the following factors: 1- Conversion to a mass-production scale: The metal output, which amounted to approximately 10 tons in 1952, practically doubled each year, reaching successive figures of 80 tons in 1955, 160 tons in 1956 and 300 tons in 1957. At this very moment the output capacity of the plant is approaching its maximum, set at 500 tons/year, which it will reach at the end of the year. Beyond this output figure, the work will be carried on by the second French uranium production plant, which is now being erected at Narbonne. 2- Gradual abandoning of ore treatment, resulting from the decentralization of the duties performed by the CEA; The Bouchet Plant had, as a matter of fact, the first French treatment facilities, operating on the basis of 10 to 20 tons of ore per day. This ore, first concentrated at the production site proper by means of physical or physico-chemical methods to at least a 2 per cent uranium content, was sufficiently valuable to warrant quite well the cost involved in shipping it. However, the increase in the production schedules led to the treatment of ores of lower and lower grades, and it became more profitable to proceed with the chemicalating of these low-grade ores at the site after more or less thorough grading and, if necessary, preconcentration. As a result, the Bouchet plant scarcely ever receives uranium ores; on the contrary, the mining companies send their chemical concentrates, uranous phosphate and then sodium uranate from the Gueugnon Works in Saone-et-Loire since 1955; magnesium uranate from the Ecarpiere Works in Vendee since the beginning of 1957 and, very soon, products from the works which are now being

Evaluation of acid leaching method for the determination of uranium in fecal samples from occupational workers at Tarapur

International Nuclear Information System (INIS)

Raveendran, Nanda; Dubla, Rupali; Yadav, J.R.; Rao, D.D.; Baburajan, A.

2015-01-01

Assessment of internal contamination due to inhalation, ingestion or injection of radionuclides to occupational workers is carried out by analysis of excreta samples and whole body counting. Routine monitoring of radiation workers for assessing actinides intake are done either by urine or fecal sample analysis. This paper deals with the evaluation of analytical method for the determination of isotopes of uranium in fecal samples submitted by occupational workers from operating plants at Tarapur. The method involves sample ashing, addition of 232 U tracer for radiochemical recovery and acid leaching preconcentration stage followed by anion exchange separation. Thirteen routine fecal samples submitted by radiation workers under their routine monitoring practices were collected and analyzed. Radiochemical tracer recovery was obtained in the range of 52% to 86.4 % with a mean and standard deviation of 64.7% and 12.3% respectively. (author)

Flow injection on-line preconcentration of low levels of Cr(VI) with detection by ETAAS

DEFF Research Database (Denmark)

Som-aum, Waraporn; Liawruangrath, Saisunee; Hansen, Elo Harald

2002-01-01

A flow injection (FI) on-line sorption preconcentration procedure utilizing a packed column reactor and combined with electrothermal atomic absorption spectrometry (ETAAS) is proposed for the determination of low levels of Cr(VI) in water samples. Polytetrafluoroethylene (PTFE) beads packed in a ...

Petrography and geochemistry of granitoids from the Samphire Pluton, South Australia: Implications for uranium mineralisation in overlying sediments

Science.gov (United States)

Domnick, Urs; Cook, Nigel J.; Bluck, Russel; Brown, Callan; Ciobanu, Cristiana L.

2018-02-01

The Blackbush uranium deposit (JORC Inferred Resource: 12,580 tonnes U), located on the north-eastern Eyre Peninsula, is currently the only sediment-hosted U deposit investigated in detail in the Gawler Craton. Uranium is hosted within Eocene sandstone of the Kanaka Beds, overlying Mesoproterozoic granites of the Samphire pluton, affiliated with the Hiltaba Intrusive Suite ( 1.6 Ga). These are considered the most probable source rocks for uranium mineralisation. By constraining the petrography and mineralogy of the granites, insights into the post-emplacement evolution can be gained, which may provide an exploration indicator for other sediment-hosted uranium systems. Three geochemically distinct granite types were identified in the Samphire Pluton and correspond to domains interpreted from geophysical data. All granites show complex alteration overprints and textures with increasing intensity closer to the deposit, as well as crosscutting veining. Alkali feldspar has been replaced by porous K-feldspar and albite, and plagioclase is overprinted by an assemblage of porous albite + sericite ± calc-silicates (prehnite, pumpellyite and epidote). This style of feldspar alteration is regionally widespread and known from Hiltaba-aged granites associated with iron-oxide copper-gold mineralisation at Olympic Dam and in the Moonta-Wallaroo region. In two granite types biotite is replaced by calcic garnet. Calc-silicates are indicative of Ca-metasomatism, sourced from the anorthite component of altered plagioclase. Minor clay alteration of feldspars is present in all samples. Mineral assemblages in veins include quartz + hematite, hematite + coffinite, fluorite + quartz, and clay minerals. Minor chlorite and sericite are found in all vein types. All granite types are anomalously rich in U (concentrations between 10 and 81 ppm). Highly variable Th/U ratios, as well as hydrothermal U minerals (mostly coffinite) in granites and veins, are clear evidence for U mobility. Uranium

Lyotropic liquid crystal preconcentrates for the treatment of periodontal disease.

Science.gov (United States)

Fehér, A; Urbán, E; Eros, I; Szabó-Révész, P; Csányi, E

2008-06-24

The aim of our study was to develop water-free lyotropic liquid crystalline preconcentrates, which consist of oils and surfactants with good physiological tolerance and spontaneously form lyotropic liquid crystalline phase in aqueous environment. In this way these preconcentrates having low viscosity can be injected into the periodontal pocket, where they are transformed into highly viscous liquid crystalline phase, so that the preparation is prevented from flowing out of the pocket due to its great viscosity, while drug release is controlled by the liquid crystalline texture. In order to follow the structure alteration upon water absorption polarization microscopical and rheological examinations were performed. The water absorption mechanism of the samples was examined by the Enslin-method. Metronidazole-benzoate was used as active agent the release of which was characterized via in vitro investigations performed by means of modified Kirby-Bauer disk diffusion method. On the grounds of the results it can be stated that the 4:1 mixture of the investigated surfactants (Cremophor EL, Cremophor RH40) and oil (Miglyol 810) formed lyotopic liquid crystalline phases upon water addition. Polarization microscopic examinations showed that samples with 10-40% water content possessed anisotropic properties. On the basis of water absorption, rheological and drug release studies it can be concluded that the amount of absorbed water and stiffness of lyotropic structure influenced by the chemical entity of the surfactant exerted major effect on the drug release.

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

Flow injection on-line spectrophotometric determination of thorium(IV) after preconcentration on XAD-4 resin impregnated with oxytetracycline

Energy Technology Data Exchange (ETDEWEB)

Shahida, Shabnam; Khan, Muhammad Haleem [Univ. of Azad Jammu and Kashmir, Muzaffarabad (Pakistan). Dept. of Chemistry; Ali, Akbar [Pakistan Institute of Nuclear Science and Technology, Islamabad (Pakistan). Chemistry Div.

2014-02-15

A very sensitive, selective and simple flow injection time-based method was developed for on-line preconcentration and determination of thorium(IV) at micro g L{sup -1} levels in environmental samples. The system operation was based on thorium(IV) ion retention at pH 4.0 in the minicolumn at a flow rate of 15.2 mL min{sup -1}. The trapped complex was then eluted with 3.6 mol L{sup -1} HCl at a flow rate of 4.9 mL min{sup -1}. The amount of thorium(IV) in the eluate was measured spectrophotometrically at 651 nm using arsenazo-III solution (0.05 % in 3.6 mol L{sup -1} HCl stabilized with 1 % triton X-100, 4.9 mL min{sup -1}) as colorimetric reagent. All chemical, and flow injection variables were optimized for the quantitative preconcentration of metal and a study of interference level of various ions was also carried out. The system offered low backpressure and improved sensitivity and selectivity. At a preconcentration time of 60 s and a sample frequency of 40 h{sup -1}, the enhancement factor was 97, the detection limit was 0.25 μg L{sup -1}, and the precision expressed as relative standard deviation was 1.08 % (at 50 μg L{sup -1}), whereas for 300 s of the preconcentration time and a sample frequency of 10 h{sup -1}, the enhancement factor of 357, the detection limit (3s) of 0.069 μg L{sup -1} and the precision of 1.32 % (at 10 μg L{sup -1}) was reported. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference material IAEA-SL-1 (Lake Sediment) and spiked water samples.

Flow injection on-line spectrophotometric determination of thorium(IV) after preconcentration on XAD-4 resin impregnated with oxytetracycline

International Nuclear Information System (INIS)

Shahida, Shabnam; Khan, Muhammad Haleem; Ali, Akbar

2014-01-01

A very sensitive, selective and simple flow injection time-based method was developed for on-line preconcentration and determination of thorium(IV) at micro g L"-"1 levels in environmental samples. The system operation was based on thorium(IV) ion retention at pH 4.0 in the minicolumn at a flow rate of 15.2 mL min"-"1. The trapped complex was then eluted with 3.6 mol L"-"1 HCl at a flow rate of 4.9 mL min"-"1. The amount of thorium(IV) in the eluate was measured spectrophotometrically at 651 nm using arsenazo-III solution (0.05 % in 3.6 mol L"-"1 HCl stabilized with 1 % triton X-100, 4.9 mL min"-"1) as colorimetric reagent. All chemical, and flow injection variables were optimized for the quantitative preconcentration of metal and a study of interference level of various ions was also carried out. The system offered low backpressure and improved sensitivity and selectivity. At a preconcentration time of 60 s and a sample frequency of 40 h"-"1, the enhancement factor was 97, the detection limit was 0.25 μg L"-"1, and the precision expressed as relative standard deviation was 1.08 % (at 50 μg L"-"1), whereas for 300 s of the preconcentration time and a sample frequency of 10 h"-"1, the enhancement factor of 357, the detection limit (3s) of 0.069 μg L"-"1 and the precision of 1.32 % (at 10 μg L"-"1) was reported. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference material IAEA-SL-1 (Lake Sediment) and spiked water samples.

IAEA sends out samples of uranium ore

Energy Technology Data Exchange (ETDEWEB)

NONE

1966-06-15

Full text: Governments and organizations interested in developing uranium resources will be assisted by a new service, now being inaugurated by the Agency's laboratories, for the distribution of reference samples of uranium ores. This is an addition to the service which began at Seibersdorf in January 1962 for the distribution of calibrated radionuclides, and which has met with a steadily increasing demand. * Uranium deposits consisting of ores with a uranium content in the range 0.5 - 0.05 per cent occur in a number of countries, including developing countries and can present considerable analytical difficulties. In 1962 the Agency asked Member States whether they would be interested in receiving reference samples of uranium ores to assist them in checking their methods of chemical analysis. The response encouraged the Agency to proceed. There is a multiplicity of types of uranium ores and, initially, three of the most commonly occurring have been selected - torbernite, uraninite and carnotite. Member States have provided the laboratory with supplies of these three types of ore. In order to determine the uranium content, samples are sent to leading laboratories throughout the world, so as to arrive at the most accurate values possible. This work has proved to be useful to the laboratories themselves ; in searching for reasons for discrepancies between the different collaborating laboratories, they enlarge their own knowledge and improve their methods. The reference samples are sent out in the form of fine powder, and are available to atomic energy commissions, research laboratories or mining companies. The requesting laboratory, having worked out the analytical process best suited to its needs, is then able to check its results by analysing an IAEA reference sample of known uranium content. By the end of 1966, reference samples will be available of the three ores mentioned, and later also of pure uranium oxide and of uranium oxide containing trace impurities, the

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.

Bioleaching of uranium in batch stirred tank reactor: Process optimization using Box–Behnken design

International Nuclear Information System (INIS)

Eisapour, M.; Keshtkar, A.; Moosavian, M.A.; Rashidi, A.

2013-01-01

Highlights: ► High amount of uranium recovery achieved using Acidithiobacillus ferrooxidans. ► ANOVA shows individual variables and their squares are statistically significant. ► The model can accurately predict the behavior of uranium recovery. ► The model shows that pulp density has the greatest effect on uranium recovery. - Abstract: To design industrial reactors, it is important to identify and optimize the effective parameters of the process. Therefore, in this study, a three-level Box–Behnken factorial design was employed combining with a response surface methodology to optimize pulp density, agitation speed and aeration rate in uranium bioleaching in a stirred tank reactor using a pure native culture of Acidithiobacillus ferrooxidans. A mathematical model was then developed by applying the least squares method using the software Minitab Version 16.1.0. The second order model represents the uranium recovery as a function of pulp density, agitation speed and aeration rate. An analysis of variance was carried out to investigate the effects of individual variables and their combined interactive effects on uranium recovery. The results showed that the linear and quadratic terms of variables were statistically significant whilst the interaction terms were statistically insignificant. The model estimated that a maximum uranium extraction (99.99%) could be obtained when the pulp density, agitation speed and aeration rate were set at optimized values of 5.8% w/v, 510 rpm and 250 l/h, respectively. A confirmatory test at the optimum conditions resulted in a uranium recovery of 95%, indicating a marginal error of 4.99%. Furthermore, control tests were performed to demonstrate the effect of A. ferrooxidans in uranium bioleaching process and showed that the addition of this microorganism greatly increases the uranium recovery

Methods of pre-concentration of radionuclides from large volume samples

International Nuclear Information System (INIS)

Olahova, K.; Matel, L.; Rosskopfova, O.

2006-01-01

The development of radioanalytical methods for low level radionuclides in environmental samples is presented. In particular, emphasis is placed on the introduction of extraction chromatography as a tool for improving the quality of results as well as reducing the analysis time. However, the advantageous application of extraction chromatography often depends on the effective use of suitable preconcentration techniques, such as co-precipitation, to reduce the amount of matrix components which accompany the analysis interest. On-going investigations in this field relevant to the determination of environmental levels of actinides and 90 Sr are discussed. (authors)

Preconcentration of heavy metals on activated carbon and their determination in fruits by inductively coupled plasma optical emission spectrometry.

Science.gov (United States)

Feist, Barbara; Mikula, Barbara

2014-03-15

A method of separation and preconcentration of cadmium, cobalt, copper, nickel, lead, and zinc at trace level using activated carbon is proposed. Activated carbon with the adsorbed trace metals was mineralised using a high-pressure microwave mineraliser. The heavy metals were determined after preconcentration by inductively coupled plasma optical emission spectrometry (ICP-OES). The influence of several parameters, such as pH, sorbent mass, shaking time was examined. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The experiment shows that foreign ions did not influence recovery of the determined elements. The detection limits (DL) of Cd, Co, Cu, Ni, Pb, and Zn were 0.17, 0.19, 1.60, 2.60, 0.92 and 1.50 μg L(-)(1), respectively. The recovery of the method for the determined elements was better than 95% with relative standard deviation from 1.3% to 3.7%. The preconcentration factor was 80. The proposed method was applied for determination of Cd, Co, Cu, Ni, Pb, and Zn in fruits materials. Accuracy of the proposed method was verified using certified reference material (NCS ZC85006 Tomato). Copyright © 2013 Elsevier Ltd. All rights reserved.

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.)

Reverse osmosis performance of cellulose acetate membranes in the separation of uranium from dilute solutions

International Nuclear Information System (INIS)

Sastri, V.S.; Ashbrook, A.W.

1976-01-01

Batch 316-type cellulose acetate membranes were characterized in terms of pure water permeability constant, solute transport parameter, and mass transfer coefficient with a reference system of aqueous sodium chloride solution. These membranes were used in the determination of reverse osmosis characteristics such as product rate and solute separation in the case of uranium sulfate solutions of different concentrations (100 to 8000 ppM) in the feed solutions. A long-term test extending over a week has been carried out with dilute uranium solutions. Reverse osmosis treatment of synthetic mine water sample showed satisfactory performance of the membranes in the separation of metal ions

Comparative analysis of uranium bioassociation with halophilic bacteria and archaea

Science.gov (United States)

Bader, Miriam; Müller, Katharina; Foerstendorf, Harald; Schmidt, Matthias; Simmons, Karen; Swanson, Juliet S.; Reed, Donald T.; Stumpf, Thorsten

2018-01-01

Rock salt represents a potential host rock formation for the final disposal of radioactive waste. The interactions between indigenous microorganisms and radionuclides, e.g. uranium, need to be investigated to better predict the influence of microorganisms on the safety assessment of the repository. Hence, the association process of uranium with two microorganisms isolated from rock salt was comparatively studied. Brachybacterium sp. G1, which was isolated from the German salt dome Gorleben, and Halobacterium noricense DSM15987T, were selected as examples of a moderately halophilic bacterium and an extremely halophilic archaeon, respectively. The microorganisms exhibited completely different association behaviors with uranium. While a pure biosorption process took place with Brachybacterium sp. G1 cells, a multistage association process occurred with the archaeon. In addition to batch experiments, in situ attenuated total reflection Fourier-transform infrared spectroscopy was applied to characterize the U(VI) interaction process. Biosorption was identified as the dominating process for Brachybacterium sp. G1 with this method. Carboxylic functionalities are the dominant interacting groups for the bacterium, whereas phosphoryl groups are also involved in U(VI) association by the archaeon H. noricense. PMID:29329319

Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with off-line column preconcentration using 2,6-diacetylpyridine functionalized Amberlite XAD-4

Energy Technology Data Exchange (ETDEWEB)

Karadas, Cennet [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Kara, Derya, E-mail: dkara@balikesir.edu.tr [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Fisher, Andrew [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom)

2011-03-18

An off-line column preconcentration technique using a micro-column of 2,6 diacetylpyridine functionalized Amberlite XAD-4 with inductively coupled plasma mass spectrometry (ICP-MS) as a means of detection has been developed. The aim of the method was to determine rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. Sample solutions (2-10 mL) were passed through the column which was then washed with ultra-pure water to remove residual matrix. The adsorbed cations on the resin were eluted by using 2 mL of 0.1 mol L{sup -1} HNO{sub 3} containing 10 ng mL{sup -1} indium as an internal standard. The eluent was analyzed for the metal concentrations using ICP-MS. Sample pH as well as the sample and eluent flow rates were optimized. The sorption capacity of resin was determined by the batch process, by equilibrating 0.05 g of the resin with solutions of 50 mL of 25 mg L{sup -1} of individual metal ions for 4 h at pH 6.0 at 26 deg. C. The sorption capacities for the resin were found to range between 47.3 {mu}mol g{sup -1} (for Lu) and 136.7 {mu}mol g{sup -1} (for Gd). Limits of detection (3{sigma}), without any preconcentration, ranged from 2 ng L{sup -1} to 10.3 ng L{sup -1} (for Tm and Lu respectively). The proposed method was applied to the determination of REEs in seawater and tap water samples.

Lead preconcentration in synthetic samples with triton x-114 in the cloud point extraction and analysis by atomic absorption (EAAF)

International Nuclear Information System (INIS)

Zegarra Pisconti, Marixa; Cjuno Huanca, Jesus

2015-01-01

A methodology was developed about lead preconcentration in water samples that were added dithizone as complexing agent, previously dissolved in the nonionic surfactant Triton X-114, until the formation of the critical micelle concentration and the cloud point temperature. The centrifuged system gave a precipitate with high concentrations of Pb (II) that was measured by atomic absorption spectroscopy with flame (EAAF). The method has proved feasible to be implemented as a method of preconcentration and analysis of Pb in aqueous samples with concentrations less than 1 ppm. Several parameters were evaluated to obtain a percentage recovery of 89.8%. (author)

Calculation of U, Ra, Th and K contents in uranium ore by multiple linear regression method

International Nuclear Information System (INIS)

Lin Chao; Chen Yingqiang; Zhang Qingwen; Tan Fuwen; Peng Guanghui

1991-01-01

A multiple linear regression method was used to compute γ spectra of uranium ore samples and to calculate contents of U, Ra, Th, and K. In comparison with the inverse matrix method, its advantage is that no standard samples of pure U, Ra, Th and K are needed for obtaining response coefficients

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...

Activation of the C-H bond: catalytic hydroxylation of hydrocarbons by new cobaltic alkylperoxydic complexes; selective and catalytic cycloalkane dehydrogenation in presence of uranium for hydrogen transfer

International Nuclear Information System (INIS)

Brazi, E.

1987-01-01

The aim of the thesis is to improve efficiency and selectivity of chemical reactions for alkane transformations. In the first part decomposition of hydroperoxides and hydrocarbon hydroxylation by cobalt complexes is studied. In the second part cycloalkanes are dehydrogenated into aromatics with a Pt catalyst, trapping hydrogen by uranium. Uranium hydride UH 3 can yield very pure hydrogen at reasonable temperature [fr

Detection and evaluation of uranium in different minerals by gamma spectrometry and laser induced breakdown spectroscopy

International Nuclear Information System (INIS)

Sergani, F.M.; Khedr, M.A.; Harith, M.A.; El Mongy, S.A.

2004-01-01

Analysis, detection and evaluation of source nuclear materials (e.g. uranium) in different minerals by sensitive techniques are a vital objective for uranium exploration, nuclear materials extraction, processing and verification. In this work, uranium in different geological formations was determined using gamma spectrometry and laser induced breakdown spectroscopy (LIBS). The investigated samples were collected from different regions distributed all over Egypt. The samples were then prepared for non-destructive analysis. A hyper pure germanium detector was used to measure the emitted gamma rays of uranium and its daughters in the samples. The concentrations of uranium in ppm (μg/g) in the investigated samples are given and discussed in this work. The highest uranium concentration (4354.9 ppm) was found in uranophane samples of Gattar rocks. In Laser induced breakdown spectroscopy (LIBS) technique, plasma was formed by irradiating the rock surface with focused Q-switched Nd:Yag laser pulses of 7 ns pulse duration at the fundamental wavelength (1064 nm). Atoms and ions originating from the rock surface are excited and ionized in the laser produced hot plasma (∝10 000 K). The plasma emission spectral line is characteristic of the elements present in the plasma and allows identification of the uranium in the uranophane mineral. The strong atomic line at 424.2 nm is used for the qualitative identification of uranium. It can be mentioned that the elevated levels of uranium in some of the investigated uranophane samples are of great economic feasibility to be extracted. (orig.)

Studies on neutron activation analysis using ion exchange preconcentration Pt. 6

International Nuclear Information System (INIS)

Hirose, A.; Ishii, D.

1978-01-01

Three convenient procedures are described for applying anion exchange resins to the preconcentration and irradiation support in neutron activation analysis. For each procedure the amounts of interferences were determined. The effect of the form, cross-linkage, pore size, and particle size of the resins on the elimination of interferences was investigated. Some other associated problems are also presented, viz. effect of concentration and temperature of washing solution, effect of irradiation time, and comparison with filter paper. Tabulated data are presented. (author)

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.)

Electrochemical preconcentration and hydride generation methods for trace determination of selenium by atomic absorption spectrometry

International Nuclear Information System (INIS)

Bye, R.

1986-01-01

The use of atomic absorption spectrometry in combination with two different preconcentration/separation techniques for the determination of trace concentrations of selenium is described. Electrochemical preconcentration onto a platinum electrode with a subsequent atomization of selenium is discussed briefly. Several parameters are considered such as the presence of depolarizers, and the temperature of the electrolyzed solutions. Special attention is payed to the efficiency of the atomization step, and a method to improve this is proposed. Applications of the technique to real samples are also reported. Secondly, the separation of the selenium as the volatile selenium hydride from the sample solution is considered. Several papers in this thesis deal with commonly occurring interferants as nickel and copper and with ways of minimizing or avoiding the interferring effects, whereas other papers relate to more theoretical aspects of the hydride generation process. New methods for the determination of selenium in technical samples with high contents of nickel and copper are also presented

Radionuclide sorption in Yucca Mountain tuffs with J-13 well water: Neptunium, uranium, and plutonium. Yucca Mountain site characterization program milestone 3338

International Nuclear Information System (INIS)

Triay, I.R.; Cotter, C.R.; Kraus, S.M.; Huddleston, M.H.

1996-08-01

We studied the retardation of actinides (neptunium, uranium, and plutonium) by sorption as a function of radionuclide concentration in water from Well J-13 and of tuffs from Yucca Mountain. Three major tuff types were examined: devitrified, vitric, and zeolitic. To identify the sorbing minerals in the tuffs, we conducted batch sorption experiments with pure mineral separates. These experiments were performed with water from Well J-13 (a sodium bicarbonate groundwater) under oxidizing conditions in the pH range from 7 to 8.5. The results indicate that all actinides studied sorb strongly to synthetic hematite and also that Np(V) and U(VI) do not sorb appreciably to devitrified or vitric tuffs, albite, or quartz. The sorption of neptunium onto clinoptilolite-rich tuffs and pure clinoptilolite can be fitted with a sorption distribution coefficient in the concentration range from 1 X 10 -7 to 3 X 10 -5 M. The sorption of uranium onto clinoptilolite-rich tuffs and pure clinoptilolite is not linear in the concentration range from 8 X 10 -8 to 1 X 10 -4 M, and it can be fitted with nonlinear isotherm models (such as the Langmuir or the Freundlich Isotherms). The sorption of neptunium and uranium onto clinoptilolite in J-13 well water increases with decreasing pH in the range from 7 to 8.5. The sorption of plutonium (initially in the Pu(V) oxidation state) onto tuffs and pure mineral separates in J-13 well water at pH 7 is significant. Plutonium sorption decreases as a function of tuff type in the order: zeolitic > vitric > devitrified; and as a function of mineralogy in the order: hematite > clinoptilolite > albite > quartz

Spectrophotometric determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction.

Science.gov (United States)

Lemos, Valfredo Azevedo; dos Santos, Liz Oliveira; Silva, Eldevan dos Santos; Vieira, Emanuel Vitor dos Santos

2012-01-01

A simple method for the determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction is described. The procedure is based on the extraction of mercury in the form of a complex and its subsequent determination by spectrophotometry. The complex is formed between Hg(II) and 2-(2-benzothiazolylazo)-p-cresol. The detection at 650 nm is performed directly in the metal-rich phase, which is spread on a triacetylcellulose membrane. The method eliminates the need to use a cuvet or large quantities of samples and reagents. The parameters that influence the preconcentration were studied, and the analytical characteristics were determined. The enrichment factor and the consumptive index for this method were 64 and 0.16 mL, respectively. The LOD (3.3 microg/L) and LOQ (11.1 microg/L) were also determined. The accuracy of the method was tested by the determination of mercury in certified reference materials BCR 397 (Human Hair) and SRM 2781 (Domestic Sludge). The method was applied to the determination of mercury in samples of drinking water, sea water, and river water.

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.)

A paper-polymer centrifugal device for low-cost sample pre-concentration and colorimetric lateral flow assay enhancement

CSIR Research Space (South Africa)

Wiederoder, MS

2016-10-01

Full Text Available This study describes a novel hybrid paper-polymer centrifugal microfluidic device for pre-concentration of E.coli and lateral flow immunoassay enhancement for water quality verification. The device balances rotational centrifugal force...

Handbook on surficial uranium deposits. Chapter 3. World distribution relative to climate and physical setting

International Nuclear Information System (INIS)

Carlisle, D.

This chapter discusses regional controls which affect the world distribution of surficial chemogenic uranium deposits. The most important of these are (1) climate, (2) geomorphology, including physiographic and climatic stability, and (3) provenance, i.e., the weathering terrain from which uranium and associated substances are derived. The three economically important environments are the calcrete environment, simple evaporative environments and paludal environments. Of these three categories, the calcrete uranium environment is probably the most uniquely constrained in terms of regional climate, geomorphic setting, provenance (vanadium as well as uranium) and especially the need for long term stability of both climate and physiography. Purely evaporative deposits, though subject to some of the same kinds of constraints, can also reflect local circumstances and a wider range of climates, physiographic settings, and source terrains. The third category encompassing bogs, marshes and organic-rich playas can form under an even wider range of climates and settings provided only that organic materials accumulate in abundance and are contacted by uranium-bearing waters. For all of these reasons and also because of the great economic importance of the calcrete environment as well as its relative novelty and complexity the discussion in this chapter is focused on calcrete, dolocrete and gypcrete uranium deposits. Objective data are reviewed first follwed by inferences and suggestions. 13 figures

Uranium mine venting during operation of self-propelled Diesel engine mechanisms

International Nuclear Information System (INIS)

Hemer, M.

1983-01-01

A draft directive has been issued for the ventilation of uranium mines which takes into consideration the concentration of radon daughter products, radon volume activity as well as the concentration of harmful wastes emitted by the Diesel engines of mining mechanisms. The mathematical relations are given for the calculation of the required amount of pure mine winds. Also listed are the technical requirements for ventilation, dust emission and the control and maintenance of mining mechanisms. (M.D.)

Lead ultra-trace on-line preconcentration and determination using selective solid phase extraction and electrothermal atomic absorption spectrometry: applications in seawaters and biological samples

Energy Technology Data Exchange (ETDEWEB)

Vereda Alonso, E.; Siles Cordero, M.T.; Garcia de Torres, A.; Cano Pavon, J.M. [University of Malaga, Department of Analytical Chemistry Faculty of Sciences, Malaga (Spain)

2006-08-15

In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 Aa; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO{sub 3}, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml{sup -1} of lead. At a sample frequency of 36 h{sup -1} with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml{sup -1}, respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml{sup -1}). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too. (orig.)

Uranium

International Nuclear Information System (INIS)

Stewart, E.D.J.

1974-01-01

A discussion is given of uranium as an energy source in The Australian economy. Figures and predictions are presented on the world supply-demand position and also figures are given on the added value that can be achieved by the processing of uranium. Conclusions are drawn about Australia's future policy with regard to uranium (R.L.)

Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent - Cold vapor atomic absorption spectrometry

International Nuclear Information System (INIS)

Duan Taicheng; Song Xuejie; Xu Jingwei; Guo Pengran; Chen Hangting; Li Hongfei

2006-01-01

Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO 3 and subsequently reduced by NaBH 4 to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min -1 sample loading rate. The detection limit was 0.2 ng L -1 and much lower than that of conventional method (around 15.8 ng L -1 ). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L -1 of Hg and the linear working curve is from 20 to 2000 ng L -1 (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory

Uranium, depleted uranium, biological effects

International Nuclear Information System (INIS)

2001-01-01

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)

Effect of rare earth elements on uranium electrodeposition in LiCl-KCI eutectic salt

International Nuclear Information System (INIS)

Park, Sung Bin; Kang, Young Ho; Hwang, Sung Chan; Lee, Han Soo; Peak, Seung Woo; Ahn, Do Hee

2015-01-01

It is necessary to investigate the electrodeposition behavior of uranium and other elements on the cathode in the electrorefining process to recover the uranium selectively from the reduced metals of the electrolytic reduction process since transuranic elements and rare earth elements is dissolved in the LiCl-KCl eutectic salt. Study on separation factors of U, Ce, Y and Nd based on U and Ce was performed to investigate the deposition behavior of the cathode with respect to the concentration of rare earth elements in LiCl-KCl eutectic salt. After electrorefining with constant current mode by using Ce metal as a sacrifice anode, the contents of U, Ce, Y and Nd in the salt phase and the deposit phase of the cathode were analyzed, and separation factors of the elements were obtained from the analyses. Securing conditions of pure uranium recovery in the electrorefining process was investigated by considering the separation factors with respect to UCl 3 and CeCl 3 /UCl 3 ratio

Effects of gas phase impurities on the topochemical-kinetic behaviour of uranium hydride development

International Nuclear Information System (INIS)

Bloch, J.; Brami, D.; Kremner, A.; Mintz, M.H.; Ben-Gurion Univ. of the Negev, Beersheba

1988-01-01

The hydriding kinetics of bulk uranium and U-0.1 wt.% Cr, in the presence of oxidizing gaseous impurities (oxygen and CO), were studied by combined rate measurements and metallographic examinations of partially reacted samples. The effect of the gaseous impurity (type and concentration) was examined metallographically, and the kinetic data were discussed in relation to these examinations. Below about 100 0 C the reaction of uranium with pure hydrogen consists of the following sequence of steps: (i) Surface nucleation; (ii) homogeneous growth (pitting); (iii) relatively fast lateral growth leading to the formation of a reaction front which penetrates into the sample at a constant rate. The effects of oxygen and CO on the hydriding kinetics were related to their abilities to block hydrogen penetration into the uranium. Thus, it was found that oxygen affects only the penetration through the oxide layer, whereas CO affects the penetration through both the oxide and hydride layers. (orig.)

Successive Recovery of Copper and Uranium From Carbonate-Rich Latosol, Um Bogma Formation, Abuthor Locality, South Western Sinai, Egypt

International Nuclear Information System (INIS)

El-Sheikh, E.M.; Amin, M.M.; Aita, S.K.; Rezk, A.A.

2013-01-01

A technological sample of a copper/ uranium mineralization in carbonate rich latosol rock sequence of Urn Bogma Formation Abu Thor locality at southwestern Sinai, Egypt, has been properly processed. The working sample assaying 12.5 % CuO and 875 ppm U was subjected to adipic acid leaching for copper followed by bioleaching of uranium in a manner to avoid excessive acid consumption in the classical leaching procedure. It is thus possible to achieve leaching efficiencies of 95% for Cu in the first stage and 82% for U in the second stage. From the two separately obtained leach liquors of Cu and uranium, pure products have conveniently been prepared. Accordingly, Cu adipate product was first prepared by crystallization,followed by acid dissolution and alkali precipitation of copper hydroxide. In case of uranium, the impure precipitate of the bioleach liquor is purified via Amberlite IRA-400 anion exchanger resin

Solubility measurement of uranium in uranium-contaminated soils

International Nuclear Information System (INIS)

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

1993-08-01

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

Uranium complex recycling method of purifying uranium liquors

International Nuclear Information System (INIS)

Elikan, L.; Lyon, W.L.; Sundar, P.S.

1976-01-01

Uranium is separated from contaminating cations in an aqueous liquor containing uranyl ions. The liquor is mixed with sufficient recycled uranium complex to raise the weight ratio of uranium to said cations preferably to at least about three. The liquor is then extracted with at least enough non-interfering, water-immiscible, organic solvent to theoretically extract about all of the uranium in the liquor. The organic solvent contains a reagent which reacts with the uranyl ions to form a complex soluble in the solvent. If the aqueous liquor is acidic, the organic solvent is then scrubbed with water. The organic solvent is stripped with a solution containing at least enough ammonium carbonate to precipitate the uranium complex. A portion of the uranium complex is recycled and the remainder can be collected and calcined to produce U 3 O 8 or UO 2

Solid-phase extraction method for preconcentration of trace amounts of some metal ions in environmental samples using silica gel modified by 2,4,6-trimorpholino-1,3,5-triazin

International Nuclear Information System (INIS)

Madrakian, Tayyebeh; Zolfigol, Mohammad Ali; Solgi, Mohammad

2008-01-01

A method was proposed for the preconcentration of some transition elements at trace levels using a column packed with silica gel modified by a synthetic ligand. Metal ions were adsorbed on 2,4,6-trimorpholino-1,3,5-triazin modified silica gel, then analytes retained on the adsorbent were eluted by 1 mol L -1 hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The influences of some experimental parameters including pH of the sample solution, weight of adsorbent, type, concentration and volume of eluent, flow rates of the sample solution and eluent, and sample volume on the preconcentration efficiency have been investigated. The influences of some matrix elements were also examined. The method also was used for simultaneous preconcentration of these elements and the method was successfully applied to the preconcentration and determination of them. The detection limits of the method for Ni 2+ , Co 2+ , Cd 2+ and Zn 2+ were 0.29, 0.20, 0.23 and, 0.30 ng mL -1 , respectively. The application of this modified silica gel to preconcentration of investigated cation from tap water, lake water, urine and apple leaves gave high accuracy and precision (relative standard deviation (R.S.D.) <3%)

Titrimetric determination of uranium in low-grade ores by the ferrous ion-phosphoric acid reduction method

International Nuclear Information System (INIS)

Hitchen, A.; Zechanowitsch, G.

1980-01-01

The modification and extension of the U.S.A.E.C. ferrous ion-phosphoric acid reduction method for the determination of uranium in high-grade or relatively pure material to a method for the determination of uranium with a high accuracy and precision, in ores containing 0.004 to 7% U is described. It is simple, rapid and requires no prior separations from elements that, in other methods, frequently interfere. For sample materials having very high concentrations of interfering elements, a prior concentration step using extraction with tri-n-octylphosphine oxide is described, but it is shown that, for most low-grade ores, this step is unnecessary. (author)

Uranium

International Nuclear Information System (INIS)

Toens, P.D.

1981-03-01

The geological setting of uranium resources in the world can be divided in two basic categories of resources and are defined as reasonably assured resources, estimated additional resources and speculative resources. Tables are given to illustrate these definitions. The increasing world production of uranium despite the cutback in the nuclear industry and the uranium requirements of the future concluded these lecture notes

Model experiments to test the use of a liquid membrane for separation and preconcentration of copper from natural water

Energy Technology Data Exchange (ETDEWEB)

Granado-Castro, Maria D.; Galindo-Riano, Maria D.; Garcia-Vargas, Manuel

2004-03-17

The transfer and separation of Cu(II) ions across a bulk liquid membrane (BLM) containing pyridine-2-acetaldehyde benzoylhydrazone (2-APBH) as the mobile carrier dissolved in toluene has been investigated and optimised. The system was applied to the preconcentration of copper from natural waters prior to analysis by flame atomic absorption spectroscopy. The flux of copper across the membrane has been studied, and characterised as a function of analytical variables such as the carrier concentration, volume of organic phase, pH of feed and strip receiving solutions, stirring rate and temperature of solutions. The preconcentration yield at optimum conditions was 100.54{+-}0.94%, even with a high saline matrix (30 g l{sup -1} NaCl), with good precision (1.49%). A preconcentration factor of approximately 18 times could be obtained. The detection limit of a blank sample was 0.24 {mu}g l{sup -1} of Cu. The method was validated using a certified reference material (TMDA-62) and was applied successfully to the analysis of copper in two samples of seawater collected from the coast of Huelva (Spain). The relative errors were 2.42% for CRM and 0.48 and 3.66%, for seawaters (obtained between the results of the proposed and DPASV methods), respectively.

Recovery of uranium from uranium bearing black shale

International Nuclear Information System (INIS)

Das, Amrita; Yadav, Manoj; Singh, Ajay K.

2016-01-01

Black shale is the unconventional resource of uranium. Recovery of uranium from black shale has been carried out by the following steps: i) size reduction, ii) leaching of uranium in the aqueous medium, iii) fluoride ion removal, iv) solvent extraction of uranium from the aqueous leach solution, v) scrubbing of the loaded solvent after extraction to remove impurities as much as possible and vi) stripping of uranium from the loaded organic into the aqueous phase. Leaching of black shale has been carried out in hydrochloric acid. Free acidity of the leach solution has been determined by potentiometric titration method. Removal of fluoride ions has been done using sodium chloride. Solvent extraction has been carried out by both tributyl phosphate and alamine-336 as extractants. Scrubbing has been tried with oxalic acid and sulphuric acid. Stripping with sodium carbonate solution has been carried out. Overall recovery of uranium is 95%. (author)

Uranium resources, 1983

International Nuclear Information System (INIS)

1983-01-01

The specific character of uranium as energy resources, the history of development of uranium resources, the production and reserve of uranium in the world, the prospect regarding the demand and supply of uranium, Japanese activity of exploring uranium resources in foreign countries and the state of development of uranium resources in various countries are reported. The formation of uranium deposits, the classification of uranium deposits and the reserve quantity of each type are described. As the geological environment of uranium deposits, there are six types, that is, quartz medium gravel conglomerate deposit, the deposit related to the unconformity in Proterozoic era, the dissemination type magma deposit, pegmatite deposit and contact deposit in igneaus rocks and metamorphic rocks, vein deposit, sandstone type deposit and the other types of deposit. The main features of respective types are explained. The most important uranium resources in Japan are those in the Tertiary formations, and most of the found reserve belongs to this type. The geological features, the state of yield and the scale of the deposits in Ningyotoge, Tono and Kanmon Mesozoic formation are reported. Uranium minerals, the promising districts in the world, and the matters related to the exploration and mining of uranium are described. (Kako, I.)

Uranium management activities

International Nuclear Information System (INIS)

Jackson, D.; Marshall, E.; Sideris, T.; Vasa-Sideris, S.

2001-01-01

One of the missions of the Department of Energy's (DOE) Oak Ridge Office (ORO) has been the management of the Department's uranium materials. This mission has been accomplished through successful integration of ORO's uranium activities with the rest of the DOE complex. Beginning in the 1980's, several of the facilities in that complex have been shut down and are in the decommissioning process. With the end of the Cold War, the shutdown of many other facilities is planned. As a result, inventories of uranium need to be removed from the Department facilities. These inventories include highly enriched uranium (HEU), low enriched uranium (LEU), normal uranium (NU), and depleted uranium (DU). The uranium materials exist in different chemical forms, including metals, oxides, solutions, and gases. Much of the uranium in these inventories is not needed to support national priorities and programs. (author)

On-line preconcentration and determination of mercury in biological and environmental samples by cold vapor-atomic absorption spectrometry

International Nuclear Information System (INIS)

Ferrua, N.; Cerutti, S.; Salonia, J.A.; Olsina, R.A.; Martinez, L.D.

2007-01-01

An on-line procedure for the determination of traces of total mercury in environmental and biological samples is described. The present methodology combines cold vapor generation associated to atomic absorption spectrometry (CV-AAS) with preconcentration of the analyte on a minicolumn packed with activated carbon. The retained analyte was quantitatively eluted from the minicolumn with nitric acid. After that, volatile specie of mercury was generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the atomizer device. Optimizations of both, preconcentration and mercury volatile specie generation variables were carried out using two level full factorial design (2 3 ) with 3 replicates of the central point. Considering a sample consumption of 25 mL, an enrichment factor of 13-fold was obtained. The detection limit (3σ) was 10 ng L -1 and the precision (relative standard deviation) was 3.1% (n = 10) at the 5 μg L -1 level. The calibration curve using the preconcentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limit up to at least 1000 μg L -1 . Satisfactory results were obtained for the analysis of mercury in tap water and hair samples

Provision by the uranium and uranium products

International Nuclear Information System (INIS)

Elagin, Yu.P.

2005-01-01

International uranium market is converted from the buyer market into the seller market. The prices of uranium are high and the market attempts to adapt to changing circumstances. The industry of uranium enrichment satisfies the increasing demands but should to increase ots capacities. On the whole the situation is not stable and every year may change the existing position [ru

Uranium industry framework

International Nuclear Information System (INIS)

Riley, K.

2008-01-01

The global uranium market is undergoing a major expansion due to an increase in global demand for uranium, the highest uranium prices in the last 20 years and recognition of the potential greenhouse benefits of nuclear power. Australia holds approximately 27% of the world's uranium resources (recoverable at under US$80/kg U), so is well placed to benefit from the expansion in the global uranium market. Increasing exploration activity due to these factors is resulting in the discovery and delineation of further high grade uranium deposits and extending Australia's strategic position as a reliable and safe supplier of low cost uranium.

High-temperature thermal conductivity of uranium chromite and uranium niobate

International Nuclear Information System (INIS)

Fedoseev, D.V.; Varshavskaya, I.G.; Lavrent'ev, A.V.; Oziraner, S.N.; Kuznetsova, D.G.

1979-01-01

The technique of determining thermal conductivity coefficient of uranium niobate and uranium chromite on heating with laser radiation is described. Determined is the coefficient of free-convective heat transfer (with provision for a conduction component) by means of a standard specimen. The thermal conductivity coefficients of uranium chromite and niobate were measured in the 1300-1700 K temperature range. The results are presented in a diagram form. It has been calculated, that the thermal conductivity coefficient for uranium niobate specimens is greater in comparison with uranium chromite specimens. The thermal conductivity coefficients of the materials mentioned depend on temperature very slightly. Thermal conductivity of the materials considerably depends on their porosity. The specimens under investigation were fabricated by the pressing method and had the following porosity: uranium chromite - 30 %, uranium niobate - 10 %. Calculation results show, that thermal conductivity of dense uranium chromite is higher than thermal conductivity of dense uranium niobate. The experimental error equals approximately 20 %, that is mainly due to the error of measuring the temperature equal to +-25 deg, with a micropyrometer

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.

From carbon nanostructures to high-performance sorbents for chromatographic separation and preconcentration

International Nuclear Information System (INIS)

Postnov, V N; Rodinkov, O V; Moskvin, L N; Novikov, A G; Bugaichenko, A S; Krokhina, O A

2016-01-01

Information on carbon nanostructures (fullerenes, nanotubes, graphene, nanodiamond and nanodispersed active carbon) used to develop high-performance sorbents of organics and heavy metal ions from aqueous solutions is collected and analyzed. The advantages in the synthesis of hybrid carbon nanostructures and the possibilities of surface modification of these systems in order to carry out fast sorption pre-concentration are considered. Prospects for application of these materials in sorption technologies and analytical chemistry are discussed. The bibliography includes 364 references

Uranium rich granite and uranium productive granite in south China

Energy Technology Data Exchange (ETDEWEB)

Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

2012-07-15

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Uranium rich granite and uranium productive granite in south China

International Nuclear Information System (INIS)

Feng Mingyue; He Debao

2012-01-01

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Uranium industry annual 1996

International Nuclear Information System (INIS)

1997-04-01

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

Uranium industry annual 1996

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-04-01

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

Production of sized particles of uranium oxides and uranium oxyfluorides

International Nuclear Information System (INIS)

Knudsen, I.E.; Randall, C.C.

1976-01-01

A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

Uranium 2000 : International symposium on the process metallurgy of uranium

International Nuclear Information System (INIS)

Ozberk, E.; Oliver, A.J.

2000-01-01

The International Symposium on the Process Metallurgy of Uranium has been organized as the thirtieth annual meeting of the Hydrometallurgy Section of the Metallurgical Society of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM). This meeting is jointly organized with the Canadian Mineral Processors Division of CIM. The proceedings are a collection of papers from fifteen countries covering the latest research, development, industrial practices and regulatory issues in uranium processing, providing a concise description of the state of this industry. Topics include: uranium industry overview; current milling operations; in-situ uranium mines and processing plants; uranium recovery and further processing; uranium leaching; uranium operations effluent water treatment; tailings disposal, water treatment and decommissioning; mine decommissioning; and international regulations and decommissioning. (author)

Electrochemical Detection with Preconcentration: Nitroenergetic Contaminants

Directory of Open Access Journals (Sweden)

Brandy J. Johnson

2014-06-01

Full Text Available This effort evaluated the potential of two prototype devices for enhanced electrochemical detection of 2,4,6-trinitrotoluene (TNT and dinitrotoluene (DNT following preconcentration using an organosilicate sorbent. The bench-scale prototype provides adsorption of the targets from aqueous solution followed by elution in a mixture of methanol and potassium chloride (KCl. Following elution, the eluant is diluted using an aqueous KCl solution to provide sufficient electrolyte for electrochemical analysis. Concentrations of methanol greater than 50% were detrimental to sensor performance and lifetime. Calibration of the electrochemical sensor was completed and results of electrochemical analysis were compared to those of HPLC analysis over a range of concentrations and in varied matrices. TNT detection was found to be consistent and detection limits were improved from 200 ppb to 3 ppb depending on the sample volume utilized. DNT detection showed higher variability and significantly greater false response rates. On the basis of these results, a second, more advanced, prototype was developed and utilized in limited field trials with the intention of moving the technology toward in situ applications.

Development of a versatile sample preparation method and its application for rare-earth pattern and Nd isotope ratio analysis in nuclear forensics

International Nuclear Information System (INIS)

Krajko, J.

2015-01-01

An improved sample preparation procedure for trace-levels of lanthanides in uranium-bearing samples was developed. The method involves a simple co-precipitation using Fe(III) carrier in ammonium carbonate medium to remove the uranium matrix. The procedure is an effective initial pre-concentration step for the subsequent extraction chromatographic separations. The applicability of the method was demonstrated by the measurement of REE pattern and 143 Nd/ 144 Nd isotope ratio in uranium ore concentrate samples. (author)

Biological characterization of radiation exposure and dose estimates for inhaled uranium milling effluents. Annual progress report April 1, 1982-March 31, 1983

International Nuclear Information System (INIS)

Eidson, A.F.

1984-05-01

The problems addressed are the protection of uranium mill workers from occupational exposure to uranium through routine bioassay programs and the assessment of accidental worker exposures. Comparisons of chemical properties and the biological behavior of refined uranium ore (yellowcake) are made to identify important properties that influence uranium distribution patterns among organs. These studies will facilitate calculations of organ doses for specific exposures and associated health risk estimates and will identify important bioassay procedures to improve evaluations of human exposures. A quantitative analytical method for yellowcake was developed based on the infrared absorption of ammonium diuranate and U 3 O 8 mixtures in KBr. The method was applied to yellowcake samples obtained from six operating mills. The composition of yellowcake from the six mills ranged from nearly pure ammonium diuranate to nearly pure U 3 O 8 . The composition of yellowcake samples taken from lots from the same mill was only somewhat less variable. Because uranium mill workers might be exposed to yellowcake either by contamination of a wound or by inhalation, a study of retention and translocation of uranium after subcutaneous implantation in rats was done. The results showed that 49% of the implanted yellowcake cleared from the body with a half-time (T sub 1/2) in the body of 0.3 days, and the remainder was cleared with a T sub 1/2 of 11 to 30 days. Exposures of Beagle dogs by nose-only inhalation to aerosols of commercial yellowcake were completed. Biochemical indicators of kidney dysfunction that appeared in blood and urine 4 to 8 days after exposure to the more soluble yellowcake showed significant changes in dogs, but levels returned to normal by 16 days after exposure. No biochemical evidence of kidney dysfunction was observed in dogs exposed to the less soluble yellowcake form. 18 figures, 9 tables

Uranium Industry Annual, 1992

International Nuclear Information System (INIS)

1993-01-01

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

Uranium Industry Annual, 1992

Energy Technology Data Exchange (ETDEWEB)

1993-10-28

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

Evaluation of uranium dioxide thermal conductivity using molecular dynamics simulations

International Nuclear Information System (INIS)

Kim, Woongkee; Kaviany, Massoud; Shim, J. H.

2014-01-01

It can be extended to larger space, time scale and even real reactor situation with fission product as multi-scale formalism. Uranium dioxide is a fluorite structure with Fm3m space group. Since it is insulator, dominant heat carrier is phonon, rather than electrons. So, using equilibrium molecular dynamics (MD) simulation, we present the appropriate calculation parameters in MD simulation by calculating thermal conductivity and application of it to the thermal conductivity of polycrystal. In this work, we investigate thermal conductivity of uranium dioxide and optimize the parameters related to its process. In this process, called Green Kubo formula, there are two parameters i.e correlation length and sampling interval, which effect on ensemble integration in order to obtain thermal conductivity. Through several comparisons, long correlation length and short sampling interval give better results. Using this strategy, thermal conductivity of poly crystal is obtained and comparison with that of pure crystal is made. Thermal conductivity of poly crystal show lower value that that of pure crystal. In further study, we broaden the study to transport coefficient of radiation damaged structures using molecular dynamics. Although molecular dynamics is tools for treating microscopic scale, most macroscopic issues related to nuclear materials such as voids in fuel materials and weakened mechanical properties by radiation are based on microscopic basis. Thus, research on microscopic scale would be expanded in this field and many hidden mechanism in atomic scales will be revealed via both atomic scale simulations and experiments

Preconcentration and atomization of arsane in a dielectric barrier discharge with detection by atomic absorption spectrometry

Czech Academy of Sciences Publication Activity Database

Novák, Petr; Dědina, Jiří; Kratzer, Jan

2016-01-01

Roč. 88, č. 11 (2016), s. 6064-6070 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * arsenic preconcentration Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 6.320, year: 2016

Depleted uranium

International Nuclear Information System (INIS)

Huffer, E.; Nifenecker, H.

2001-02-01

This document deals with the physical, chemical and radiological properties of the depleted uranium. What is the depleted uranium? Why do the military use depleted uranium and what are the risk for the health? (A.L.B.)

RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS

Science.gov (United States)

Gens, T.A.

1962-07-10

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

Synthesis and characterization of chitosan impregnated calcium alginate beads for removal of uranium from aquatic stream

International Nuclear Information System (INIS)

Singhal, R.K.; Basu, H.; Manisha, V.; Reddy, A.V.R.; Sawant, Manjiri; Kamane, Suman

2015-01-01

The present study was conducted to study the feasibility of chitosan impregnated calcium alginate beads (Cal-Alg-Chi) to sorb the excess uranium from the aquatic stream. Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). The optimal composition of calcium alginate chitosan beads is 4 % (wt/vol) alginate gel having 5% loading of chitosan. The nature and morphology of pure and uranium sorbed calcium alginate chitosan beads were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATRFTIR). The results of batch sorption experiments suggest that Cal-Alg-Chi beads are very effective for removal of uranium in the pH range of 2.0-5.0 and sorption is more than 80 % in the concentration range of 1-100 mgL -1

Study on a Salt Evaporation of the Uranium Deposits from an Electro-refiner

International Nuclear Information System (INIS)

Sung Bin Park; Dong Wook Cho; Gyu Hwan Oh; Jong Hyeon Lee; Sung Chan Hwang; Young Ho Kang; Han Soo Lee; Eung Ho Kim; Seong Won Park

2008-01-01

Uranium metal is electrodeposited onto a solid cathode during the electrorefining process. Uranium deposits from an electro-refiner contain about 30∼40 wt% salts. In order to recover pure uranium and transform it into metal ingots, the salts have to be removed. A salt distiller is adapted for a salt evaporation. A batch operation for the salt removal is carried out by a heating and vacuum evaporation. It is operated at 700 ∼ 1000 deg. C and less than 1 Torr, respectively. The behaviors of the salt evaporations were investigated by focusing on the effects of the vacuum pressure and the holding temperature on the salt distillation. The salt removal efficiencies were obtained with regards to the operational conditions. The Hertz-Langmuir relation was applied to the experimental results of the salt evaporations. The effective evaporation coefficients of the relation were obtained with regards to the operational conditions. The lower the vacuum pressure and the higher the holding temperature were, the higher the removal efficiencies of the salts were. (authors)

Determination of ultratrace amounts of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization/ICP-MS

International Nuclear Information System (INIS)

Nakamura, Yasushi; Kobayashi, Yoshio; Kakurai, Yousuke

1993-01-01

A method has been developed for determining the 0.01 ng g -1 level of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization (ETV)/ICP-MS. This method was found to be significantly interfered with any matrices or other elements contained. An ion-exchange technique was therefore applied to separate uranium and thorium from aluminium and other elements. It was known that uranium are adsorbed on an anion-exchange resin and thorium are adsorbed on cation-exchange resin. However, aluminium and copper were eluted with 6 M hydrochloric acid. Dissolve the sample with hydrochloric acid containing copper which was added for analysis of pure aluminium, and oxidize with hydrogen peroxide. Concentration of hydrochloric acid in the solution was adjusted to 6 M, and then passed the solution through the mixed ion-exchange resin column. After the uranium and thorium were eluted with 1 M hydrofluoric acid-0.1 M hydrochloric acid, the solution was evaporated to dryness. It was then dissolved with 1 M hydrochloric acid. Uranium and thorium were analyzed by ETV/ICP-MS using tungsten and molybdenum boats, respectively, since the tungsten boat contained high-level thorium and the molybdenum boat contained uranium. The determination limit of uranium and thorium were 0.003 and 0.005 ng g -1 , respectively. (author)

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.)

Inverse method for determining radon diffusion coefficient and free radon production rate of fragmented uranium ore

International Nuclear Information System (INIS)

Ye, Yong-jun; Wang, Li-heng; Ding, De-xin; Zhao, Ya-li; Fan, Nan-bin

2014-01-01

The radon diffusion coefficient and the free radon production rate are important parameters for describing radon migration in the fragmented uranium ore. In order to determine the two parameters, the pure diffusion migration equation for radon was firstly established and its analytic solution with the two parameters to be determined was derived. Then, a self manufactured experimental column was used to simulate the pure diffusion of the radon, the improved scintillation cell method was used to measure the pore radon concentrations at different depths of the column loaded with the fragmented uranium ore, and the nonlinear least square algorithm was used to inversely determine the radon diffusion coefficient and the free radon production rate. Finally, the solution with the two inversely determined parameters was used to predict the pore radon concentrations at some depths of the column, and the predicted results were compared with the measured results. The results show that the predicted results are in good agreement with the measured results and the numerical inverse method is applicable to the determination of the radon diffusion coefficient and the free radon production rate for the fragmented uranium ore. - Highlights: • Inverse method for determining two transport parameters of radon is proposed. • A self-made experimental apparatus is used to simulate radon diffusion process. • Sampling volume and position for measuring radon concentration are optimized. • The inverse results of an experimental sample are verified

Preconcentration system for cadmium and lead determination in environmental samples using polyurethane foam/Me-BTANC

International Nuclear Information System (INIS)

Moreira Gama, Ednilton; Silva Lima, Adriana da; Azevedo Lemos, Valfredo

2006-01-01

In this work, polyurethane foam (PUF) loaded with 2-(6'-methyl-2'-benzothiazolylazo)chromotropic acid (Me-BTANC) was packed in a minicolumn and it was used in an on-line preconcentration system for cadmium and lead determination. Optimum hydrodynamic and chemical conditions for metal sorption were investigated. The effects of several foreign substances on the adsorption of cadmium and lead were also reported. The enrichment factor obtained was 37 (Cd and Pb) for 180 s preconcentration time. The proposed procedures allowed the determination of metals with detection limits (3σ) of 0.80 and 3.75 μg L -1 (0.10 and 0.47 μg g -1 of solid sample) for cadmium and lead, respectively. The precision of the procedures was also calculated: 3.1 (Cd 10 μg L -1 ) and 4.4% (Pb 100 μg L -1 ). The accuracy of the procedure was checked by analysis of the certified reference materials Spinach Leaves and Fish Tissue. Cadmium and lead contents in environmental samples (black tea, spinach leaves, natural and tap water) were determined by applying the proposed procedure

Uranium health physics

International Nuclear Information System (INIS)

1980-01-01

This report contains the papers delivered at the Summer School on Uranium Health Physics held in Pretoria on the 14 and 15 April 1980. The following topics were discussed: uranium producton in South Africa; radiation physics; internal dosimetry and radiotoxicity of long-lived uranium isotopes; uranium monitoring; operational experience on uranium monitoring; dosimetry and radiotoxicity of inhaled radon daughters; occupational limits for inhalation of radon-222, radon-220 and their short-lived daughters; radon monitoring techniques; radon daughter dosimeters; operational experience on radon monitoring; and uranium mill tailings management

Uranium supply and demand

Energy Technology Data Exchange (ETDEWEB)

Spriggs, M J

1976-01-01

Papers were presented on the pattern of uranium production in South Africa; Australian uranium--will it ever become available; North American uranium resources, policies, prospects, and pricing; economic and political environment of the uranium mining industry; alternative sources of uranium supply; whither North American demand for uranium; and uranium demand and security of supply--a consumer's point of view. (LK)

Determination of trace heavy metals in soil and sediments by atomic spectrometry following preconcentration with Schiff bases on Amberlite XAD-4

Energy Technology Data Exchange (ETDEWEB)

Kara, Derya, E-mail: dkara@balikesir.edu.tr [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Fisher, Andrew; Hill, Steve J. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom)

2009-06-15

A matrix separation and analyte preconcentration system using Amberlite XAD copolymer resins functionalized by Schiff base reactions coupled with atomic spectrometry has been developed. Three different functionalized Amberlite XAD resins were synthesized using 4-phenylthiosemicarbazide, 2,3-dihydroxybenzaldehyde and 2-thiophenecarboxaldehyde as reagents. These resins could be used to preconcentrate transition and other trace heavy metal analytes from nitric acid digests of soil and sediment samples. Analyte retention was shown to work well at pH 6.0. After treatment of the digests with sodium fluoride and buffering to pH 6, samples that contain extremely large concentrations of iron were analysed for trace analytes without the excess iron overloading the capacity of the resin. The analytes Cd, Co, Cu, Ni and Pb were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with 0.1 M HNO{sub 3} directly to the detection system. Flame atomic absorption spectrometry was used as a means of detection during the studies. The efficiency of the chelating resin and the accuracy of the proposed method were evaluated by the analysis of soil (SO-2) and sediment (LGC 6157 and MESS-3) certified reference materials.

Determination of low cadmium concentrations in wine by on-line preconcentration in a knotted reactor coupled to an inductively coupled plasma optical emission spectrometer with ultrasonic nebulization

Energy Technology Data Exchange (ETDEWEB)

Lara, R.F. [Inst. de Investigaciones Mineras, Universidad Nacional de San Juan (Argentina); Wuilloud, R.G.; Salonia, J.A. [Dept. of Analytical Chemistry, National University of San Luis (Argentina); Olsina, R.A.; Martinez, L.D. [Dept. of Analytical Chemistry, National University of San Luis (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)

2001-12-01

An on-line cadmium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated to flow injection (FI) with ultrasonic nebulization system (USN) was studied. The cadmium was retained as the cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, Cd-(5-Br-PADAP), complex, at pH 9.5. The cadmium complex was removed from the knotted reactor (KR) with 3.0 mol/L nitric acid. A total enhancement factor of 216 was obtained with respect to ICP-OES using pneumatic nebulization (12 for USN and 18 for KR) with a preconcentration time of 60 s. The value of the detection limit for the preconcentration of 5 mL of sample solution was 5 ng/L. The precision for 10 replicate determinations at the 5 {mu}g/L Cd level was 2.9% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for cadmium was linear with a correlation coefficient of 0.9998 at levels near the detection limits up to at least 1000 {mu}g/L. The method was successfully applied to the determination of cadmium in wine samples. (orig.)

The application of iterative transformation factor analysis to resolve multi-component EXAFS spectra of uranium(6) complexes with acetic acid as a function of pH

International Nuclear Information System (INIS)

Robberg, A.; Reich, T.

2002-01-01

Synchrotron-based EXAFS spectroscopy is a powerful technique to obtain structural information on radionuclide complexes in solution. Depending on the chemical conditions of the samples several radionuclide species can coexist in the solution as is often the case for environmentally related samples. All radionuclide species, which may have different near-neighbour environments, contribute to the measured EXAFS signal. In order to isolate the EXAFS spectra of the individual species (pure spectral components), it is necessary, in a first step, to measure a series of samples where their composition is changed by variation of one physico-chemical parameter (e.g. pH, concentration, etc.). For the spectral decomposition it is necessary that the EXAFS signal change as a function of the chosen physico-chemical parameter. In a second step, the series of EXAFS spectra is analysed with Eigen analysis and Iterative Transformation Factor Analysis (ITFA). As a result of the ITFA one obtains: a) for each sample the relative concentration of the structural distinguishable species and b) their corresponding pure spectral components. From the information obtained in a), one can construct a speciation diagram. The pure spectral components contain the structural information of the individual species, which can be extracted by conventional EXAFS analysis. To evaluate our ITFA algorithm for EXAFS analysis of mixtures, we prepared a series of eight solution samples of 0.05 M uranium(VI) and 1 M acetate (Ac) in the pH range of 0.1 to 4.5. From thermodynamic constants it is known that under these conditions up to four species can occur: uranyl hydrate, and the 1:1, 1:2 and 1:3 complexes of uranyl acetate. The uranium L III -edge EXAFS spectra were measured at room temperature in transmission mode at the Rossendorf Beamline (ROBL) at the ESRF. The average bond length between uranium and the equatorial oxygen atoms (O eq ) increases from 2.40 to 2.46 angstrom with increasing pH. This increase

MEMS-based Porous Silicon Preconcentrators Filled with Carbopack-B for Explosives Detection

OpenAIRE

Camara , El Hadji Malik; James , Franck; Breuil , Philippe; Pijolat , Christophe; Briand , Danick; De Rooij , Nicolaas F

2014-01-01

International audience; In this paper we report the detection of explosive compounds using a miniaturized gas preconcentrator (μGP) made of porous silicon (PS) filled in with Carbopack B as an adsorbent material. The μGP includes also a platinum heater patterned at the backside and fluidic connectors sealed on the glass cover. Our μGP is designed and optimized through fluidic and thermal simulations for meeting the requirements of trace explosives detection. The thermal mass of the device was...

Uranium industry annual, 1991

International Nuclear Information System (INIS)

1992-10-01

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

Development of a technique of preparation of uranium screens for soft X Ray spectrography (1960); Mise au point d'une technique de preparation d'ecrans d'uranium pour la spectrographie de rayons X mous (1960)

Energy Technology Data Exchange (ETDEWEB)

Bersuder, L de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1961-07-01

The present work concerns the preparation of thin layers of pure uranium (thickness 100 to 1000 Angstrom) by thermal evaporation under vacuum. The protection of uranium against oxidation is obtained by using aluminium deposits under and above the uranium layer. The purity of the layers obtained is checked by electron diffraction and the necessary conditions to avoid oxidation and alloy formation during the formation of deposit are studied. Three methods for measuring the thickness are examined: by {alpha} particle counting, by weighing the condensed mass and by weighing the evaporated mass. The method using {alpha} particle counting turned to be the most accurate for low thickness layers. (author) [French] Le present travail concerne la preparation de couches minces d'uranium pur (epaisseurs de 100 a 1000 Angstrom) par evaporation thermique sous vide. La protection de l'uranium contre l'oxydation par l'air est obtenue grace a des couches d'aluminium deposees sous vide sous et sur la couche d'uranium. La purete des couches obtenues est verifiee par diffraction d'electrons et les conditions necessaires pour eviter l'oxydation et la formation d'alliages lors du depot sont etudiees. Trois methodes de mesure des epaisseurs sont examinees, mesure par comptage de particules {alpha}, mesure par pesee de la masse condensee et mesure par pesee de la masse evaporee. La mesure par comptage de particules {alpha} s'avere etre la plus precise pour les couches de faibles epaisseurs. (auteur)

On-line coupling of sample preconcentration by LVSEP with gel electrophoretic separation on T-channel chips.

Science.gov (United States)

Kitagawa, Fumihiko; Kinami, Saeko; Takegawa, Yuuki; Nukatsuka, Isoshi; Sueyoshi, Kenji; Kawai, Takayuki; Otsuka, Koji

2017-01-01

To achieve an on-line coupling of the sample preconcentration by a large-volume sample stacking with an electroosmotic flow pump (LVSEP) with microchip gel electrophoresis (MCGE), a sample solution, a background solution for LVSEP and a sieving solution for MCGE were loaded in a T-form channel and three reservoirs on PDMS microchips. By utilizing the difference in the flow resistance of the two channels, a low-viscosity sample and a viscous polymer solution were easily introduced into the LVSEP and MCGE channels, respectively. Fluorescence imaging of the sequential LVSEP-MCGE processes clearly demonstrated that a faster stacking of anionic fluorescein and successive introduction into the MCGE channel can be carried out on the T-channel chip. To evaluate the preconcentration performance, a conventional MCZE analysis of fluorescein on the cross-channel chip was compared with LVSEP-MCGE on the short T-channel chip, and as a result that the value of sensitive enhancement factor (SEF) was estimated to be 370. The repeatability of the peak height was good with the RSD value of 3.2%, indicating the robustness of the enrichment performance. In the successive LVSEP-MCGE analysis of φX174/HaeIII digest, the DNA fragments were well enriched to a sharp peak in the LVSEP channel, and they were separated in the MCGE channel, whose electropherogram was well-resembled with that in the conventional MCGE. The values of SEF for the DNA fragments were calculated to be ranging from 74 to 108. Thus, the successive LVSEP-MCGE analysis was effective for both preconcentrating and separating DNA fragments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium

Energy Technology Data Exchange (ETDEWEB)

Duran, Celal, E-mail: cduran@ktu.edu.tr [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Ozdes, Duygu [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Gundogdu, Ali [Faculty of Engineering, Food Department of Food Engineering, 29100, Guemueshane (Turkey); Imamoglu, Mustafa [Department of Chemistry, Faculty of Arts and Sciences, Sakarya University, 54187 Sakarya (Turkey); Senturk, Hasan Basri [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

2011-02-28

Activated carbon was produced from tea-industry wastes (TIWAC) and employed as a low cost and effective solid phase material for the separation, preconcentration and speciation of chromium species without using a complexing agent, prior to determination by flame atomic absorption spectrometry (FAAS). The characterization of TIWAC was performed by utilizing several techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis. The adsorption experiments were conducted in a batch adsorption technique. Under the experimental conditions, Cr(VI) adsorption amount was nearly equal to zero, however the adsorption percentage of Cr(III) was in the range of 95-100%. Therefore total chromium was determined after the reduction of Cr(VI) to Cr(III) and Cr(VI) was calculated by subtracting Cr(III) concentration from total chromium concentration. The suitable conditions for adsorption and speciation processes were evaluated in terms of pH, eluent type and volume, TIWAC concentration, adsorption and desorption contact time, etc. Adsorption capacity of TIWAC was found to be 61.0 mg g{sup -1}. The detection limit for Cr(III) was found to be 0.27 {mu}g L{sup -1} and the preconcentration factor was 50 for 200 mL of sample volume. The procedure was applied to the determination and speciation of chromium in stream, tap and sea water. Also, the proposed method was applied to total chromium preconcentration in microwave digested tobacco and dried eggplant samples with satisfactory results. The method was validated by analyzing certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and the results were in good agreement with the certified values.

Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium

International Nuclear Information System (INIS)

Duran, Celal; Ozdes, Duygu; Gundogdu, Ali; Imamoglu, Mustafa; Senturk, Hasan Basri

2011-01-01

Activated carbon was produced from tea-industry wastes (TIWAC) and employed as a low cost and effective solid phase material for the separation, preconcentration and speciation of chromium species without using a complexing agent, prior to determination by flame atomic absorption spectrometry (FAAS). The characterization of TIWAC was performed by utilizing several techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis. The adsorption experiments were conducted in a batch adsorption technique. Under the experimental conditions, Cr(VI) adsorption amount was nearly equal to zero, however the adsorption percentage of Cr(III) was in the range of 95-100%. Therefore total chromium was determined after the reduction of Cr(VI) to Cr(III) and Cr(VI) was calculated by subtracting Cr(III) concentration from total chromium concentration. The suitable conditions for adsorption and speciation processes were evaluated in terms of pH, eluent type and volume, TIWAC concentration, adsorption and desorption contact time, etc. Adsorption capacity of TIWAC was found to be 61.0 mg g -1 . The detection limit for Cr(III) was found to be 0.27 μg L -1 and the preconcentration factor was 50 for 200 mL of sample volume. The procedure was applied to the determination and speciation of chromium in stream, tap and sea water. Also, the proposed method was applied to total chromium preconcentration in microwave digested tobacco and dried eggplant samples with satisfactory results. The method was validated by analyzing certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and the results were in good agreement with the certified values.

A nanocomposite disk prepared from reduced graphene oxide and gold nanoparticles for the preconcentration of heterocyclic aromatic amines prior to their determination by HPLC

International Nuclear Information System (INIS)

Tan, Connieal; Wang, Yiru; Deng, Zhuo; Xu, Na; Song, Xinhong; Liu, Haihong; Rong, Mingcong; Chen, Xi

2014-01-01

We report on a preconcentration disk for the determination of trace amounts of heterocyclic aromatic amines (HAAs) in the groups of quinoline and quinoxaline congeners as possible human carcinogens. The disk is based on nanocomposite (NC) prepared from graphene oxide as the precursor and from gold nanoparticles that act as building blocks to form a three-dimensional NC. If deposited in the sampling valve of a HPLC system, the material displays excellent extraction capability for HAAs owing to its large surface and π-π stacking interaction. Following an optimization of the extraction parameters, the method was successfully applied to the simultaneous determination of polar HAAs in meat samples with detection limit of 0.09 to 0.16 ng g −1 and recoveries of 69.5 to 122.7 %. The disk was used in more than 150 subsequent preconcentration cycles without obvious loss of the absorption capability. The results reveal that this new NC represents an excellent sorbent for purposes of preconcentration. (author)

Separation and preconcentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin in blood samples by inclusion emulsion membranes and its determination by gas chromatography.

Science.gov (United States)

Mokhtari, Bahram; Pourabdollah, Kobra

2012-10-15

The nano-mediated preconcentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin from blood samples was reported by inclusion-facilitated emulsion liquid membrane process. The novelty of this study was application of nano-baskets of calixarene and emulsion liquid membranes in selective and efficient preconcentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin. For this aim, four derivatives of p-tert-calix[4]arene bearing different sulfonamide moieties were synthesized and their inclusion-extraction parameters were optimized including calixarenes' scaffold and concentration (3, 4 wt%), diluent type in membrane, phase and treat ratios (0.8 and 0.3), mixing speed (300 rpm), and initial solute concentrations (0.1-10 pg g(-1)). The extraction efficiency was determined by dioxin's concentration using gas chromatography equipped with electron capture detector and the results revealed that in optimized operating conditions, the preconcentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin was improved and the limit of detection decreased. Copyright © 2012 Elsevier B.V. All rights reserved.

The Influence of Oxygen and Sulfur on Uranium Partitioning Into the Core

Science.gov (United States)

Moore, R. D., Jr.; Van Orman, J. A.; Hauck, S. A., II

2017-12-01

Uranium, along with K and Th, may provide substantial long-term heating in planetary cores, depending on the magnitude of their partitioning into the metal during differentiation. In general, non-metallic light elements are known to have a large influence on the partitioning of trace elements, and the presence of sulfur is known to enhance the partitioning of uranium into the metal. Data from the steelmaking literature indicate that oxygen also enhances the solubility of oxygen in liquid iron alloys. Here we present experimental data on the partitioning of U between immiscible liquids in the Fe-S-O system, and use these data along with published metal-silicate partitioning data to calibrate a quantitative activity model for U in the metal. We also determined partition coefficients for Th, K, Nb, Nd, Sm, and Yb, but were unable to fully constrain activity models for these elements with available data. A Monte Carlo fitting routine was used to calculate U-S, U-O, and U-S-O interaction coefficients, and their associated uncertainties. We find that the combined interaction of uranium with sulfur and oxygen is predominant, with S and O together enhancing the solubility of uranium to a far greater degree than either element in isolation. This suggests that uranium complexes with sulfite or sulfate species in the metal. For a model Mars core composition containing 14 at% S and 5 at% O, the metal/silicate partition coefficient for U is predicted to be an order of magnitude larger than for a pure Fe-Ni core.

Uranium price reporting systems

International Nuclear Information System (INIS)

1987-09-01

This report describes the systems for uranium price reporting currently available to the uranium industry. The report restricts itself to prices for U 3 O 8 natural uranium concentrates. Most purchases of natural uranium by utilities, and sales by producers, are conducted in this form. The bulk of uranium in electricity generation is enriched before use, and is converted to uranium hexafluoride, UF 6 , prior to enrichment. Some uranium is traded as UF 6 or as enriched uranium, particularly in the 'secondary' market. Prices for UF 6 and enriched uranium are not considered directly in this report. However, where transactions in UF 6 influence the reported price of U 3 O 8 this influence is taken into account. Unless otherwise indicated, the terms uranium and natural uranium used here refer exclusively to U 3 O 8 . (author)

Formation mechanism of uranium minerals at sandstone-type uranium deposits

International Nuclear Information System (INIS)

Li Shengfu; Zhang Yun

2004-01-01

By analyzing the behavior and existence form of uranium in different geochemical environments, existence form of uranium and uranium minerals species, this paper expounds the formation mechanism of main commercial uranium mineral--pitchblende: (1) uranium is a valence-changeable element. It is reactivated and migrates in oxidized environment, and is reduced and precipitated in reducing environment; (2) [UO 2 (CO 3 ) 3 ] 4- , [UO 2 (CO 3 ) 2 ] 2- coming from oxidized environment react with reductants such as organic matter, sulfide and low-valence iron at the redox front to form simple uranium oxide--pitchblende; (3)the adsorption of uranium by organic matter and clay minerals accelerates the reduction and the concentration of uranium. Therefore, it is considered, that the reduction of SO 4 2- by organic matter to form H 2 S, and the reduction of UO 2 2+ by H 2 S are the main reasons for the formation of pitchblende. This reaction is extensively and universally available in neutral and weakly alkaline carbonate solution. The existense of reductants such as H 2 S is the basic factor leading to the decrease of Eh in environments and the oversaturation of UO 2 2+ at the redox front in groundwater, thus accelerating the adsorption and the precipitation of uranium

Uranium enrichment

International Nuclear Information System (INIS)

1990-01-01

This report looks at the following issues: How much Soviet uranium ore and enriched uranium are imported into the United States and what is the extent to which utilities flag swap to disguise these purchases? What are the U.S.S.R.'s enriched uranium trading practices? To what extent are utilities required to return used fuel to the Soviet Union as part of the enriched uranium sales agreement? Why have U.S. utilities ended their contracts to buy enrichment services from DOE?

Australian uranium industry

Energy Technology Data Exchange (ETDEWEB)

Warner, R K

1976-04-01

Various aspects of the Australian uranium industry are discussed including the prospecting, exploration and mining of uranium ores, world supply and demand, the price of uranium and the nuclear fuel cycle. The market for uranium and the future development of the industry are described.

Uranium enrichment plans

International Nuclear Information System (INIS)

Thomas, D.C.; Gagne, R.W.

1978-01-01

The following topics are covered: the status of the Government's existing uranium enrichment services contracts, natural uranium requirements based on the latest contract information, uncertainty in predicting natural uranium requirements based on uranium enrichment contracts, and domestic and foreign demand assumed in enrichment planning

Determination of rare earth elements in natural water samples – A review of sample separation, preconcentration and direct methodologies

Energy Technology Data Exchange (ETDEWEB)

Fisher, Andrew, E-mail: afisher@plymouth.ac.uk [School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, Devon, PL4 8AA (United Kingdom); Kara, Derya [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100, Balikesir (Turkey)

2016-09-07

This review discusses and compares the methods given for the determination of rare earth elements (REE) in natural water samples, including sea, river, lake, tap, ground and waste waters as well as Antarctic ice. Since REE are at very low concentrations in natural waters, numerous different preconcentration methods have been proposed to enable their measurement. These include liquid liquid extraction, dispersive liquid-liquid micro-extraction and solidified floating drop micro-extraction. In addition to liquid-liquid extraction methods, solid phase extraction using commercial resins, resins made in-house, silica-based exchange materials and other solid media is also discussed. These and other techniques such as precipitation/co-precipitation and flotation are compared in terms of speed, preconcentration factors achieved, precision, accuracy and limits of detection (LOD). Some papers have discussed the direct determination of REE in these sample types. Some have used specialised sample introduction systems such as ultrasonic nebulization whereas others have used a standard sample introduction system coupled with inductively coupled plasma mass spectrometry (ICP-MS) detection. These direct methods have also been discussed and compared. - Highlights: • The determination of rare earth elements in waters is reviewed. • Assorted preconcentration techniques are discussed and evaluated. • Detection techniques include atomic spectrometry, potentiometry and spectrophotometry. • Special nebulisers and electrothermal vaporization approaches are reviewed.

Uranium of Kazakhstan

International Nuclear Information System (INIS)

Tsalyuk, Yu.; Gurevich, D.

2000-01-01

Over 25 % of the world's uranium reserves are concentrated in Kazakhstan. So, the world's largest Shu-Sarysu uranium province is situated on southern Kazakhstan, with resources exceeding 1 billion tonnes of uranium. No less, than 3 unique deposits with resources exceeding 100,000 tonnes are situated here. From the economic point of view the most important thing is that these deposits are suitable for in-situ leaching, which is the cheapest, environmentally friendly and most efficient method available for uranium extracting. In 1997 the Kazatomprom National Joint-Stock Company united all Kazakhstan's uranium enterprises (3 mine and concentrating plants, Volkovgeologiya Joint-Stock Company and the Ulbinskij Metallurgical plant). In 1998 uranium production came to 1,500 tonnes (860 kg in 1997). In 1999 investment to the industry were about $ 30 million. Plans for development of Kazakhstan's uranium industry provide a significant role for foreign partners. At present, 2 large companies (Comeco (Canada), Cogema (France) working in Kazakhstan. Kazakatomprom continues to attract foreign investors. The company's administration announced that in that in next year they have plan to make a radical step: to sell 67 % of stocks to strategic investors (at present 100 % of stocks belongs to state). Authors of the article regard, that the Kazakhstan's uranium industry still has significant reserves to develop. Even if the scenario for the uranium industry could be unfavorable, uranium production in Kazakhstan may triple within the next three to four years. The processing of uranium by the Ulbinskij Metallurgical Plant and the production of some by-products, such as rhenium, vanadium and rare-earth elements, may provide more profits. Obviously, the sale of uranium (as well as of any other reserves) cannot make Kazakhstan a prosperous country. However, country's uranium industry has a god chance to become one of the most important and advanced sectors of national economy

Improved limits and portability over currently employed cadmium monitoring systems through preconcentration for detection by way of micro-/nanofluidic mechanisms

Science.gov (United States)

Wach, Paul

Due to risk of environmental and biological accumulation of Cadmium (Cd), improved methods of early detection and monitoring must be explored as a preventative measure. Listed as one of the top three toxic heavy metals by the Environmental Protection Agency (EPA), the effects on ecological and human systems have well documented side-effects of physical mutation, reproductive sterility, kidney failure, liver disease, bone loss, and death. Found in batteries, metal plating, pigments, plastics, and cigarettes, Cd is also used as a neutron absorber in the nuclear industry as well as having 3 known radioactive isotopes. Urine Cd levels, which have been widely used to predict whole body levels, increase when kidney damage occurs, thus increasing the importance to monitor and detect as early as possible. Although several methods of detection and monitoring are currently in use, they are insufficient for reasons including massive expense, weak specificity causing false readings, and/or a lack of portability. By exploiting naturally occurring mechanisms known to micro-/nanofluidics, a novel approach to Cd detection, measurement, and preconcentration was explored using the finite element computational software COMSOL. An open flow system of a nanochannel was explored through manipulation of the surface charge density. With a dominant negatively charged density on the walls, positive surface charge densities were adjacently placed at the center of the nanochannel causing a constriction of flow and allowing preconcentration of the analytes. When the open flow system was scaled up to a microchannel, the mechanism was found to have little effect on constriction of the flow. A preconcentration effect was discovered in a closed flow system when the adjacent patches were modeled as being impermeable to charge, causing the molecules to migrate to and remain at the central region of the microchannel once the dynamic process reached steady state. It was found to have the ability to

Nano magnetic solid phase extraction for preconcentration of lead ions in environmental samples by a newly synthesized reagent.

Science.gov (United States)

Golshekan, Mostafa; Shariati, Shahab

2013-01-01

In this study, magnetite nanoparticles with particle size lower than 47 nm were synthesized and were applied for preconcentration of Pb2+ ions from aqueous solutions. To preconcentrate the Pb2+ ions, the surface of the synthesized nano particles was modified with sodium dodecyl sulfate (SDS) as an anionic surfactant. A new chelating agent (2-((E)-2-amino-4,5-dinitrophenylimino)methyl)phenol) was synthesized and used to form a very stable complex with Pb2+ ions. The lead ions formed complexes and were quantitatively extracted with SDS-coated magnetite nanoparticles. After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HC1 in dimethyl sulfoxide (DMSO) prior to analysis by flame atomic absorption spectrometry (FAAS). Orthogonal array design (OAD) was used to study and optimize the different experimental parameters. Under the optimum conditions, enhancement factor up to 63.5 was achieved for extraction from only 10 mL of sample solution and the relative standard deviation (RSD %) of the method was lower than 2.8%. The obtained calibration curve was linear in the range of 1-300 pg L-' with reasonable linearity (r2 > 0.998). The limit of detection (LOD) based on S/N = 3 was 0.04 microg L(-1) for 10 mL sample volumes. Finally, applicability of the proposed method was successfully confirmed by preconcentration and determination of trace amounts of lead ions in environmental samples and satisfactory results were obtained.

Uranium enrichment plans

International Nuclear Information System (INIS)

Gagne, R.W.; Thomas, D.C.

1977-01-01

The status of existing uranium enrichment contracts in the US is reviewed and expected natural uranium requirements for existing domestic uranium enrichment contracts are evaluated. Uncertainty in natural uranium requirements associated with requirements-type and fixed-commitment type contracts is discussed along with implementation of variable tails assay

Uranium speciation in plants

International Nuclear Information System (INIS)

Guenther, A.; Bernhard, G.; Geipel, G.; Reich, T.; Rossberg, A.; Nitsche, H.

2003-01-01

Detailed knowledge of the nature of uranium complexes formed after the uptake by plants is an essential prerequisite to describe the migration behavior of uranium in the environment. This study focuses on the determination of uranium speciation after uptake of uranium by lupine plants. For the first time, time-resolved laser-induced fluorescence spectroscopy and X-ray absorption spectroscopy were used to determine the chemical speciation of uranium in plants. Differences were detected between the uranium speciation in the initial solution (hydroponic solution and pore water of soil) and inside the lupine plants. The oxidation state of uranium did not change and remained hexavalent after it was taken up by the lupine plants. The chemical speciation of uranium was identical in the roots, shoot axis, and leaves and was independent of the uranium speciation in the uptake solution. The results indicate that the uranium is predominantly bound as uranyl(VI) phosphate to the phosphoryl groups. Dandelions and lamb's lettuce showed uranium speciation identical to lupine plants. (orig.)

Uranium recovering from slags generated in the metallic uranium by magnesiothermic reduction

International Nuclear Information System (INIS)

Fornarolo, F.; Carvalho, E.F. Urano de; Durazzo, M.; Riella, H.G.

2008-01-01

The Nuclear Fuel Center of IPEN/CNEN-SP has recent/y concluded a program for developing the fabrication technology of the nuclear fuel based on the U 3 Si 2 -Al dispersion, which is being used in the IEA-R1 research reactor. The uranium silicide (U 3 Si 2 ) fuel production starts with the uranium hexafluoride (UF 6 ) processing and uranium tetrafluoride (UF 4 ) precipitation. Then, the UF 4 is converted to metallic uranium by magnesiothermic reduction. The UF 4 reduction by magnesium generates MgF 2 slag containing considerable concentrations of uranium, which could reach 20 wt%. The uranium contained in that slag should be recovered and this work presents the results obtained in recovering the uranium from that slag. The uranium recovery is accomplished by acidic leaching of the calcined slag. The calcination transforms the metallic uranium in U 3 O 8 , promoting the pulverization of the pieces of metallic uranium and facilitating the leaching operation. As process variables, have been considered the nitric molar concentration, the acid excess regarding the stoichiometry and the leaching temperature. As result, the uranium recovery reached a 96% yield. (author)

Process for producing uranium oxide rich compositions from uranium hexafluoride

International Nuclear Information System (INIS)

DeHollander, W.R.; Fenimore, C.P.

1978-01-01

Conversion of gaseous uranium hexafluoride to a uranium dioxide rich composition in the presence of an active flame in a reactor defining a reaction zone is achieved by separately introducing a first gaseous reactant comprising a mixture of uranium hexafluoride and a reducing carrier gas, and a second gaseous reactant comprising an oxygen-containing gas. The reactants are separated by a shielding gas as they are introduced to the reaction zone. The shielding gas temporarily separates the gaseous reactants and temporarily prevents substantial mixing and reacting of the gaseous reactants. The flame occurring in the reaction zone is maintained away from contact with the inlet introducing the mixture to the reaction zone. After suitable treatment, the uranium dioxide rich composition is capable of being fabricated into bodies of desired configuration for loading into nuclear fuel rods. Alternatively, an oxygen-containing gas as a third gaseous reactant is introduced when the uranium hexafluoride conversion to the uranium dioxide rich composition is substantially complete. This results in oxidizing the uranium dioxide rich composition to a higher oxide of uranium with conversion of any residual reducing gas to its oxidized form

White sand potentially suppresses radon emission from uranium tailings

Science.gov (United States)

Abdel Ghany, H. A.; El Aassy, Ibrahim E.; Ibrahim, Eman M.; Gamil, S. H.

2018-03-01

Uranium tailings represent a huge radioactive waste contaminant, where radon emanation is considered a major health hazard. Many trials have been conducted to minimize radon exhalation rate by using different covering materials. In the present work, three covering materials, commonly available in the local environment, (kaolin, white sand and bentonite) have been used with different thickness 10, 15, and 20 mm). 238U, 232Th, 40K and the radon exhalation rate were measured by using gamma spectrometry with a Hyper Pure Germanium (HPGe) detector and solid state nuclear track detectors (CR-39). Radon exhalation rate, calculated before and after covering, ranged from 2.80 ± 0.14 to 4.20 ± 0.21 Bq m-2 h-1, and from 0.30 ± 0.01 to 4.00 ± 0.20 Bq m-2 h-1, respectively. Also, the attenuation coefficients of different covering materials and radon emanation were calculated. The obtained results demonstrate that covering of uranium tailings by kaolin, white sand and bentonite has potentially minimized both the radon exhalation rate and the corresponding internal doses.

Synthesis of Uranium-di-Oxide nano-particles by pulsed laser ablation in ethanol and their characterisation

International Nuclear Information System (INIS)

Kumar, Aniruddha; Prasad, Manisha; Shail, Shailini

2015-01-01

The importance of actinide based nano-structures is well known in the area of biology, nuclear medicine, and nuclear industry. Pulsed laser ablation in liquid is recognised as an attractive technique for production of nano-structures of different metals and metal oxides with high purity. In this paper, we report synthesis of uranium-di-oxide nano particles by pulsed laser ablation in ethanol. The second harmonic emission of an electro- optically Q-switched nano-second Nd-YAG laser was used as the coherent source here. The structural and optical properties of the fabricated Uranium-di-oxide nano- particles were investigated by XRD, SEM, TEM, EDX and UV- Vis-NIR spectrophotometry. The mean size of the particles was found to be dependent on the laser ablation parameters. XRD and TEM analysis confirmed the phase of the synthesised material as pure crystalline Uranium-di- oxide with Face Centred Cubic structure. UV- Vis- NIR absorption spectra of the colloidal solution show high absorption in the UV regime. (author)

Recent technical progress in the French uranium industry; Les recents progres techniques dans l'industrie de l'uranium en France

Energy Technology Data Exchange (ETDEWEB)

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

1961-07-01

This paper reviews the present-day uranium production situation in France. The various stages of the treatment the concentrates receive, leading to the final production of the metal, are described briefly: dissolution, purification by extraction with a mixture of tributyl phosphate and white spirit, precipitation with ammonia, drying and calcination of the trioxide, reduction with hydrogen, cracked ammonia or preferably pure ammonia gas, fluorination with anhydrous hydrofluoric acid, and production of the metal by the calcium thermite process. Recent work of an original nature is discussed in greater detail. (author) [French] L'expose fait le point de la technique actuelle en ce qui concerne la fabrication de l'uranium en France. Il retrace brievement les diverses etapes du traitement des concentres pour aboutir au metal: mise en solution, purification par extraction au melange phosphate de tributylo-white spirit, precipitation par l'ammoniaque, sechage et calcination du trioxyde, reduction a l'hydrogene, a l'ammoniac craque ou mieux au gaz ammoniac pur, fluoruration par l'acide fluorhydrique anhydre et elaboration du metal par calciothermie. De plus amples details sont donnes sur les realisations recentes d'un caractere original. (auteur)

Formation conditions of uranium minerals in oxidation zone of uranium deposits

International Nuclear Information System (INIS)

Li Youzhu

2005-01-01

The paper concerns about the summary and classification of hydrothermal uranium deposit with oxidation zone. Based on the summary of observation results of forty uranium deposits located in CIS and Bulgaria which are of different sizes and industrial-genetic types, analysis on available published information concerning oxidation and uranium mineral enrichment in supergenic zone, oxidation zone classification of hydrothermal uranium had been put forward according to the general system of the exogenetic uranium concentration. (authors)

International Uranium Resources Evaluation Project (IUREP) national favourability studies: Belize (Former British Honduras)

International Nuclear Information System (INIS)

1977-08-01

Belize is a well-forested area of 22,960 square kilometers. Its capital is Belmopan. The country is generally flat north of the capital city. The flat, swampy Caribbean Coast of Belize gradually ascends to the low peaks of the Maya and Cockscomb Mountains (elevation to 1,120 meters). The area south of the Maya Mountains is much more rugged than the area to the north. The country is drained by seventeen rivers, the chief ones being the Belize, Hondo, New, Sibun, Monkey and Moho. There is 'hurricane danger in the July-October period. Belize has reportedly been surveyed by Gamma Ray Spectrometer for phosphates which probably would have contained sufficient uranium to be detectable. The survey traversed about 1,000 line kms along major north-south and east-west roads as well as many secondary roads and trails. The uranium readings ranged from 0. to 9.9 ppm with a uranium content of 1-2 ppm in the limestone areas and 2-7 ppm in the alluvium-covered areas. The U/Th ratio varied from 0.11 to 1.65. A recent traverse across the Mountain Pine Ridge batholith gave one reading as high as 36 ppm but the average was about 9-10 ppm. The upper 1000-3000 feet of core and cuttings from nine deep oil wells were checked for phosphates and uranium. Most of the core and cuttings were almost pure limestones. The P 2 0 3 content was less than 0.05 percent and no uranium was detected. It is very doubtful that any significant uranium occurrences will be found in the sediments surrounding the Maya Mountain uplift. However, there is a slight chance that uranium might occur in the granites and pegmatites in the Maya Mountains. The potential of Belize is estimated to be in the less than 1.000 tonnes uranium range, considering the restricted range, of geologic environments encountered there

Depleted uranium internal contamination of US soldiers deployed in Samawah, Iraq during operation Iraqi freedom

International Nuclear Information System (INIS)

Asaf Durakovic; Isaac Zimmerman; Axel Gerdes

2004-01-01

Purpose: The purpose of this study was to analyze the concentration and precise isotopic composition and ratios of four uranium isotopes ( 234 U, 235 U, 236 U, and 238 U) in the urine of United States soldiers deployed in Samawah, Iraq during the second Gulf War. Methods: Seven active duty US soldiers deployed as military police unit 442 presenting with non-specific symptoms of intractable headaches, excessive fatigue, intermittent fevers, musculoskeletal pains, respiratory impairment, affect changes, urinary tract symptoms, and neurological alterations were clinically evaluated. Each soldier signed a consent form to participate in our study. The collection of 24-hour urine samples of each subject was performed under controlled conditions. The urine samples were personally carried to the laboratory of the Institute of Geochemistry, JW Goethe University, Frankfurt, Germany. Each sample was analyzed in duplicate by multicollector inductively coupled plasma ionization mass spectrometry (MC-ICP-MS). Control samples consisting of an internal urine standard were also analyzed by the same procedure. The analytical methodology included pre-concentration of the urine samples using evaporation, oxidation of organic matter, uranium purification by ion-exchange chromatography, and analysis by mass spectrometry. The final analysis of the specimens was performed by using a double-focusing Thermo Finnigan Neptune multicollector ICP-MS equipped with retarding potential quadrupole lens and a secondary electron multiplier for ion counting. Results: The mean concentration of total uranium was 3.6±1.3 ng/L. The average 238 U/ 235 U ratio was 146.2±10.2. The ratio of 238 U/ 235 U, being considered as the single most important parameter in determining the quantitative state of depletion of the natural uranium ratio, demonstrates a significant internal contamination with depleted uranium in four soldiers. The 234 U/ 238 U ratio was 6.5 x 10 -5 ±5.7 x 10 -6 . The 236 U/ 238 U ratio was

Uranium industry annual 1994

International Nuclear Information System (INIS)

1995-01-01

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

Control of uranium hazards - Portsmouth uranium enrichment plant

International Nuclear Information System (INIS)

Wagner, E.R.

1985-01-01

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

Nanofluidic Pre-Concentration Devices for Enhancing the Detection Sensitivity and Selectivity of Biomarkers for Human Performance Monitoring

Science.gov (United States)

2012-12-01

approximately 1.5 V/cm field strength. The preconcentration of fluorescently labeled strep- tavidin protein samples (52.8 kDa, Molecular Probes, Engene , OR, USA...Molecular Probes, Engene , OR) or ~50 nm silica nanoparticles (Corpuscular Inc., Cold Spring, NY) using an inverted microscope (Zeiss Observer A1

Uranium industry annual, 1986

International Nuclear Information System (INIS)

1987-01-01

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

Uranium Industry. Annual 1984

International Nuclear Information System (INIS)

Lawrence, M.S.S.

1985-01-01

This report provides a statistical description of activities of the US uranium industry during 1984 and includes a statistical profile of the status of the industry at the end of 1984. It is based on the results of an Energy Information Administration (EIA) survey entitled ''Uranium Industry Annual Survey'' (Form EIA-858). The principal findings of the survey are summarized under two headings - Uranium Raw Materials Activities and Uranium Marketing Activities. The first heading covers exploration and development, uranium resources, mine and mill production, and employment. The second heading covers uranium deliveries and delivery commitments, uranium prices, foreign trade in uranium, inventories, and other marketing activities. 32 figs., 48 tabs

Irradiated uranium reprocessing

International Nuclear Information System (INIS)

Gal, I.

1961-12-01

Task concerned with reprocessing of irradiated uranium covered the following activities: implementing the method and constructing the cell for uranium dissolving; implementing the procedure for extraction of uranium, plutonium and fission products from radioactive uranium solutions; studying the possibilities for using inorganic ion exchangers and adsorbers for separation of U, Pu and fission products

Uranium

International Nuclear Information System (INIS)

Anon.

1984-01-01

The article briefly discusses the Australian government policy and the attitude of political party factions towards the mining and exporting of the uranium resources in Australia. Australia has a third of the Western World's low-cost uranium resources

Modified dispersive liquid-liquid microextraction for pre-concentration of benzene, toluene, ethylbenzene and xylenes prior to their determination by GC

International Nuclear Information System (INIS)

Faraji, Hakim; Feizbakhsh, Alireza; Helalizadeh, Masoumeh

2013-01-01

We have developed a modified method for the extraction and preconcentration of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples. It based on dispersive liquid-liquid microextraction along with solidification of floating organic microdrops. The dispersion of microvolumes of an extracting solvent into the aqueous occurs without dispersive solvent. Various parameters have been optimized. BTEX were quantified via GC with FID detection. Under optimized conditions, the preconcentration factors range from 301 to 514, extraction efficiencies from 60 to 103 %, repeatabilities from 2.2 to 4.1 %, and intermediate precisions from 3.5 to 7.0 %. The relative recovery for each analyte in water samples at three spiking levels is >85.6 %, with a relative standard deviation of <7.4 %. (author)

Purification by high vacuum fusion and progressive solidification of uranium from electrolytic origin

International Nuclear Information System (INIS)

Poeydomenge, P.

1964-01-01

Within the general framework of research on uranium purification by zone melting, an attempt was made to determine the degree of purification which could be obtained by a simple gradual solidification of a normal nuclear-pure uranium paying close attention to the rate and direction of solidification. This uranium of intermediate purity would provide a starting material more suited to the first purification which is a vertical zone-melting process, so-called 'floating'. For this purpose, ingots of electrolytic uranium were melted under vacuum (2 to 5 x 10 -6 mm) in a long crucible after a slow rise in temperature to eliminate as much as possible the gases and volatiles impurities. This degassing and impurities volatilisation are completed by maintaining both at a high temperature for a considerable time. The beth is then made to solidify from the one an in the other the crucible by slowly moving the solid-liquid interface at a constant rate so as to obtain an impurity distribution according to the laws established by PFANN. Various experimental methods have made it possible to show that the metal which solidifies first is much purer than that at the other end of the ingot. The degree of purification of the metal at the beginning of the ingot has been evaluated either quantitatively by measuring the ratio of the electrical resistivities at room temperature and at the liquid nitrogen temperature, or qualitatively by an examination of the micrographic structure and by a study of the recrystallisation of the metal. On the one hand the purified metal re-crystallises during iso-chromic annealings carried out at increasing temperatures, at a temperature much lower than the initial metal or than the end of the ingot. The passage from the cold-worked state to the recrystallised state is followed by micro-hardness measurements. On the other end, only is the purified metal, strongly cold-worked by unidirectional melting, is the phenomenon of 'dissociative growth' of the grain

Uranium industry annual 1998

International Nuclear Information System (INIS)

1999-01-01

The Uranium Industry Annual 1998 (UIA 1998) provides current statistical data on the US uranium industry's activities relating to uranium raw materials and uranium marketing. It contains data for the period 1989 through 2008 as collected on the Form EIA-858, ''Uranium Industry Annual Survey.'' Data provides a comprehensive statistical characterization of the industry's activities for the survey year and also include some information about industry's plans and commitments for the near-term future. Data on uranium raw materials activities for 1989 through 1998, including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment, are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2008, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, and uranium inventories, are shown in Chapter 2. The methodology used in the 1998 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ''Uranium Industry Annual Survey'' is provided in Appendix C. The Form EIA-858 ''Uranium Industry Annual Survey'' is shown in Appendix D. For the readers convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix E along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 24 figs., 56 tabs

Preparation of uranium-230 as a new uranium tracer

International Nuclear Information System (INIS)

Hashimoto, T.; Kido, K.; Sotobayashi, T.

1977-01-01

A uranium isotope, 230 U(T=20.8 d), was produced from the 231 Pa(γ,n) 230 Pa→viaβ - decay 230 U process with a bremsstrahlung irradiation on a protactinium target. After standing for about one month to obtain a maximal growth of 230 U, the uranium was chemically purified, applying an ion-exchange method. The purity of the 230 U obtained was examined with alpha spectrometry and an intrinsic alpha peak due to 230 U as a new uranium tracer in an alpha spectrometric analysis of uranium isotopes is described. (author)

stripping of uranium from DEHPA/TOPO solvent by ammonium carbonate solutions

International Nuclear Information System (INIS)

Khorfan, S.; Shino, O.; Wahood, A.; Dahdouh, A.

2002-01-01

Uranium is recovered from phosphoric acid by the DEHPA/TOPO process. In this process uranium is stripped from the loaded DEHPA/TOPO solvent in the second cycle by an ammonium carbonate solution. This paper studied stripping of uranium from 0.3 Mol DEHPA/0.075 Mol TOPO in kerosene by different ammonium carbonate solutions. The ammonium carbonate solutions tested were either made locally from ammonia and carbon dioxide gases or commercial and laboratory grades available on the market. A comparison was made between these carbonate solutions in terms of purity, stripping efficiency and phase separation. Both stripping and phase separation were carried out under different conditions of phase ratio and concentrations. The results obtained showed that ammonium carbonate prepared from direct synthesis of ammonia and carbon dioxide gases had a high purity and gave the same stripping yield as the laboratory grade. The phase separation was also slightly improved using a pure synthesized ammonium carbonate solution. the phase separation was found to be best at concentration of 0.5 Mol/L ammonium carbonate solution and at a phase A/O of 1/1 and a temperature of 50 degree centigrade. It was possible to obtain >99% yield by operating 2 stripping stages counter currently under these conditions. (authors)

Preparation of uranium dioxide by thermal decomposition and direct reduction of ammonium uranate

International Nuclear Information System (INIS)

Hernandez R, R.

1995-01-01

The thermal decomposition of ammonium uranate has been studied by infrared spectroscopy, and X-ray diffraction. It has been show that ammonia remains in the solid until substantially 350 Centigrade degrees, when gaseous nitrogen is released. It is concluded that compounds derived from the calcination of ammonium uranate at atmospheric pressure, produced amorphous U O 3 at about 350-400 Centigrade degrees and transform to U 3 O 8 via α - U O 3 and/or α - U O 3 . The object of this study was to obtain reliable fundamental information regarding the character of the pure carbon monoxide-ammonium uranate-uranium trioxide-uranium octaoxide reaction, in the range of temperatures that has been used in commercial reduction processes. Through the use of high-purity samples and by the proper control of incidental variable, this object was realized. (Author)

Synthesis of Uranium nitride powders using metal uranium powders

International Nuclear Information System (INIS)

Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik

2012-01-01

Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N 15 gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work

Development of clinical dosage forms for a poorly water-soluble drug II: formulation and characterization of a novel solid microemulsion preconcentrate system for oral delivery of a poorly water-soluble drug.

Science.gov (United States)

Li, Ping; Hynes, Sara R; Haefele, Thomas F; Pudipeddi, Madhu; Royce, Alan E; Serajuddin, Abu T M

2009-05-01

The solution of a poorly water-soluble drug in a liquid lipid-surfactant mixture, which served as a microemulsion preconcentrate, was converted into a solid form by incorporating it in a solid polyethylene glycol (PEG) matrix. The solid microemulsion preconcentrates thus formed consisted of Capmul PG8 (propylene glycol monocaprylate) as oil, Cremophor EL (polyoxyl 35 castor oil) as surfactant, and hydrophilic polymer PEG 3350 as solid matrix. The drug (aqueous solubility: 0.17 microg/mL at pH 1-8 and 25 degrees C) was dissolved in a melt of the mixture at 65-70 degrees C and then the hot solution was filled into hard gelatin capsules; the liquid gradually solidified upon cooling below 55 degrees C. The solid system was characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), confocal Raman microscopy (CRM), and the dispersion testing in water. It was confirmed that a solid microemulsion preconcentrate is a two-phase system, where clusters of crystalline PEG 3350 formed the solid structure (m.p. 55-60 degrees C) and the liquid microemulsion preconcentrate dispersed in between PEG 3350 crystals as a separate phase. The drug remained dissolved in the liquid phase. In vitro release testing showed that the preconcentrate dispersed readily in water forming a microemulsion with the drug dissolved in the oil particles (PEG 3350 did not interfere with the process of self-microemulsification.

Uranium market

International Nuclear Information System (INIS)

Rubini, L.A.; Asem, M.A.D.

1990-01-01

The historical development of the uranium market is present in two periods: The initial period 1947-1970 and from 1970 onwards, with the establishment of a commercial market. The world uranium requirements are derived from the corresponding forecast of nuclear generating capacity, with, particular emphasis to the brazilian requirements. The forecast of uranium production until the year 2000 is presented considering existing inventories and the already committed demand. The balance between production and requirements is analysed. Finally the types of contracts currently being used and the development of uranium prices in the world market are considered. (author)

Analytical evaluation of BEA zeolite for the pre-concentration of polycyclic aromatic hydrocarbons and their subsequent chromatographic analysis in water samples.

Science.gov (United States)

Wilson, Walter B; Costa, Andréia A; Wang, Huiyong; Dias, José A; Dias, Sílvia C L; Campiglia, Andres D

2012-07-06

The analytical performance of BEA - a commercial zeolite - is evaluated for the pre-concentration of fifteen Environmental Protection Agency - polycyclic aromatic hydrocarbons and their subsequent HPLC analysis in tap and lake water samples. The pre-concentration factors obtained with BEA have led to a method with excellent analytical figures of merit. One milliliter aliquots were sufficient to obtain excellent precision of measurements at the parts-per-trillion concentration level with relative standard deviations varying from 4.1% (dibenzo[a,h]anthracene) to 13.4% (pyrene). The limits of detection were excellent as well and varied between 1.1 (anthracene) and 49.9 ng L(-1) (indeno[1,2,3-cd]pyrene). The recovery values of all the studied compounds meet the criterion for regulated polycyclic aromatic hydrocarbons, which mandates relative standard deviations equal or lower than 25%. The small volume of organic solvents (100 μL per sample) and amount of BEA (2 mg per sample) makes sample pre-concentration environmentally friendly and cost effective. The extraction procedure is well suited for numerous samples as the small working volume (1 mL) facilitates the implementation of simultaneous sample extraction. These are attractive features when routine monitoring of numerous samples is contemplated. Copyright © 2012 Elsevier B.V. All rights reserved.

Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: a review.

Science.gov (United States)

Herrero Latorre, C; Barciela García, J; García Martín, S; Peña Crecente, R M

2013-12-04

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation and preconcentration of lead(II), cobalt(II), and nickel(II) on EDTA immobilized activated carbon cloth prior to flame atomic absorption spectrometric determination in environmental samples

OpenAIRE

ALOTHMAN, ZEID ABDULLAH; YILMAZ, ERKAN; HABİLA, MOHAMED; SOYLAK, MUSTAFA

2015-01-01

The synthesis and characterization of ethylenediaminetetraacetic acid immobilized activated carbon cloth was performed in the present work. It was used for preconcentration-separation of lead(II), cobalt(II), and nickel(II) at trace levels as an adsorbent. Factors including pH, concentration and volume of eluent, sample and eluent flow rates, sample volume, and effect of coexisting ions on the solid phase extraction of analytes were examined. The preconcentration factor was 50. The detection ...

Dislocations and radiation damage in {alpha}-uranium; Dislocations et effets des radiations dans l'uranium {alpha}

Energy Technology Data Exchange (ETDEWEB)

Leteurtre, J [Commissariat a l' Energie Atomique, 92 - Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

Dislocations in {alpha}-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in {alpha}-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [French] Ce travail est une etude par microscopie electronique des dislocations induites dans l'uranium {alpha}, soit par deformation plastique, soit par irradiation. Une methode de preparation des lames minces a basse temperature (-110 deg. C) a ete mise au point. Les vecteurs de Burgers des diverses dislocations de macles de ce metal ont ete definis. Les interactions glissements- maclages sont etudiees experimentalement et theoriquement. Des echantillons irradies a divers taux de combustion ont ete examines. Pour expliquer nos resultats micrographiques, et aussi l'ensemble des informations recueillies dans la litterature concernant l'endommagement par irradiation de l'uranium-{alpha}, nous proposons un modele coherent de l'effet des fragments de fission dans ce metal. L'influence des parametres: temperature, densite de dislocations, impuretes est analysee. Le nombre de defauts ponctuels crees par une fission dans du metal

Uranium

International Nuclear Information System (INIS)

Whillans, R.T.

1981-01-01

Events in the Canadian uranium industry during 1980 are reviewed. Mine and mill expansions and exploration activity are described, as well as changes in governmental policy. Although demand for uranium is weak at the moment, the industry feels optimistic about the future. (LL)

Study on removal effect and mechanism of uranium by hydroxyapatite and natural apatite

International Nuclear Information System (INIS)

Zhang Xiaofeng; Chen Diyun; Tu Guoqing; Huang Xiaozhui

2014-01-01

By the static experiments, the effects of reaction time, pH value, initial concentration of uranium, dosage of apatite on adsorption of hydroxyapatite and natural apatite for uranium were studied respectively. The adsorption process was analyzed by thermodynamics and kinetics, and the adsorption mechanism was analyzed by infrared spectroscopy, X-ray diffraction and scanning electron microscope. The results of hydroxyapatite show that the removal capacity of uranium increases with the initial concentration of uranium, and the adsorption rate of hydroxyapatite on UO_2"2"+ reaches 85%, when the pH value is 4 to 5 and dosage of hydroxyapatite is 0.75 g. The results of natural apatite show that the removal capacity of uranium increases with the initial concentration of uranium, and the adsorption rate of natural apatite on UO_2"2"+ is up to 80%, when the pH value is 3 and dosage of hydroxyapatite is l.0 g. Similarly, at 120 minutes both of the removal reactions by hydroxyapatite and natural apatite substantially reach equilibrium. Moreover, both of the reactions by hydroxyapatite and natural apatite are in line with quasi secondary dynamics equation, and follow the Langmuir adsorption isotherm. Infrared spectra indicate that the removal of hydroxyapatite for uranium depends on the complexation of phosphate, which is almost the same as that of natural apatite. X-ray diffraction analysis shows that hydroxyapatite has the composition and structure of pure material, whereas the natural apatite is mainly composed of Ca_5H_2(PO_4)_3F and Ca_8H_2(PO_4)_6H_2O. In addition, scanning electron microscope demonstrates that hydroxyapatite has the appearance of spherical with a hole and the hole has a cavity containing a large amount of floc, while the surface becomes smooth and pores are closed after removal of uranium, which is due to the adsorption of UO_2"2"+ leading a link between molecules on hydroxyapatite surface. But for natural apatite, it depicts the angular mineral shape

Uranium industry annual 1985

International Nuclear Information System (INIS)

1986-11-01

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

Uranium

Energy Technology Data Exchange (ETDEWEB)

Williams, R M

1976-01-01

Evidence of expanding markets, improved prices and the short supply of uranium became abundantly clear in 1975, providing the much needed impetus for widespread activity in all phases of uranium operations. Exploration activity that had been at low levels in recent years in Canada was evident in most provinces as well as the Northwest Territories. All producers were in the process of expanding their uranium-producing facilities. Canada's Atomic Energy Control Board (AECB) by year-end had authorized the export of over 73,000 tons of U/sub 3/0/sub 8/ all since September 1974, when the federal government announced its new uranium export guidelines. World production, which had been in the order of 25,000 tons of U/sub 3/0/sub 8/ annually, was expected to reach about 28,000 tons in 1975, principally from increased output in the United States.