Anion analysis in uranium more concentrates by ion chromatography

International Nuclear Information System (INIS)

Badaut, V.

2009-01-01

In the present exploratory study, the applicability of anionic impurities or attributing nuclear material to a certain chemical process or origin has been investigated. Anions (e.g., nitrate, sulphate, fluoride, chloride) originate from acids or salt solutions that are used for processing of solutions containing uranium or plutonium. The study focuses on uranium ore concentrates ('yellow cakes') originating from different mines. Uranium is mined from different types of ore body and depending on the type of rock, different chemical processes for leaching, dissolving and precipitating the uranium need to be applied. Consequently, the anionic patterns observed in he products of these processes (the 'ore concentrates') are different. The concentrations of different anionic species were measured by ion chromatography using conductivity detection. The results show clear differences of anion concentrations and patterns between samples from different uranium mines. Besides this, differences between sampling campaigns n a same mine were also observed indicating that the uranium ore is not homogeneous in a mine. These within-mine variations, however, were smaller than the between-mine variations. (author)

Coprecipitation of thorium and uranium peroxides from acid solutions

Energy Technology Data Exchange (ETDEWEB)

McTaggart, D.R.; Mailen, J.C.

1981-01-01

The factors affecting successful coprecipitation of thorium and uranium peroxides from acid media were studied. Variables considered in this work were H/sup +/ concentration, H/sub 2/O/sub 2/ concentration, duration of contact, and rate of feed solution addition. In all experiments, stock solutions of Th(NO/sub 3/)/sub 4/ and UO/sub 2/(NO/sub 3/)/sub 2/ were fed at a controlled rate into H/sub 2/O/sub 2/ solutions with constant stirring. Samples were taken as a function of time to follow the H/sup +/ concentration of the solution, uranium precipitation, thorium precipitation, precipitant weight/volume of solution, and crystalline structure and growth. The optimum conditions for maximum coprecipitation are low H/sup +/ concentration, high H/sub 2/O/sub 2/ concentration, and extended contact time between the solutions.

The prediction of concentration profiles for a NIMCIX column absorbing uranium from aqueous solution

International Nuclear Information System (INIS)

Wright, R.S.

1979-01-01

A procedure is proposed for the prediction of concentration profiles for a countercurrent ion-exchange absorption column, use being made of equilibrium and kinetic data derived from small-scale batch tests. A comparison is presented between the predictions and the measured performance of a column (2,5 m in diameter) absorbing uranium from solution. The method is shown to be adequate for design purposes provided that the data used are from tests in which the solution and resin conditions approximate those for which the plant is being designed [af

Uranium concentration monitor manual: 2300 system

International Nuclear Information System (INIS)

Russo, P.A.; Sprinkle, J.K. Jr.; Stephens, M.M.

1985-04-01

This manual describes the design, operation, and procedures for measurement control for the automated uranium concentration monitor on the 2300 solvent extraction system at the Oak Ridge Y-12 Plant. The nonintrusive monitor provides a near-real time readout of uranium concentration at two locations simultaneously in the solvent extraction system for process monitoring and control. Detectors installed at the top of the extraction column and at the bottom of the backwash column acquire spectra of gamma rays from the solvent extraction solutions in the columns. Pulse-height analysis of these spectra gives the concentration of uranium in the organic product of the extraction column and in the aqueous product of the solvent extraction system. The visual readouts of concentrations for process monitoring are updated every 2 min for both detection systems. Simultaneously, the concentration results are shipped to a remote computer that has been installed by Y-12 to demonstrate automatic control of the solvent extraction system based on input of near-real time process operation information. 8 refs., 13 figs., 4 tabs

Novel precipitation technique for uranium recovery from carbonate leach solutions

International Nuclear Information System (INIS)

Sujoy Biswas; Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.; Chakravartty, J.K.

2015-01-01

The recovery of uranium from carbonate ore leach solution was studied using novel precipitation method. The uranium from leach liquor was recovered as magnesium diuranate with NaOH in presence of trace amount of Mg 2+ . Effects of various parameters such as addition of H 2 SO 4 , MgO, MgSO 4 as well as NaOH were investigated for maximum uranium recovery. Overall uranium recovery of the process was 97 % with improved particle size (∼57 µm). Based on the experimental findings, a process flow-sheet was developed for uranium recovery from carbonate ore leach solution with a uranium concentration of <1 g/L. (author)

Recovery and treatment of uranium from uranium-containing solution by liquid membrane emulsion technology

International Nuclear Information System (INIS)

Xia Liangshu; Zhou Yantong; Xiao Yiqun; Peng Anguo; Xiao Jingshui; Chen Wei

2014-01-01

The recovery and treatment of uranium from uranium-containing solution using liquid membrane emulsion (LME) technology were studied in this paper, which contained the best volume ratio of membrane materials, stirring speed during emulsion process, the conditions of extracting, such as temperature, pH, initial concentration of uranium. Moreover, the mechanism for extracting uranium was also discussed. The best experimental conditions of emulsifying were acquired. The volume fractions of P 204 and liquid paraffin are 0.1 and 0.05, the volume ratios of Span80 and sulphonated kerosene to P 204 are 0.06 and 0.79 respectively, stirring speed is controlled in 2 000 r/min, and the concentration of inner phase is 4 mol/L. The recovery rate of uranium is up to 99% through the LME extracted uranium for 0.5 h at pH 2.5 and room temperature when the initial concentration is less than 400 mg/L and the volume ratio is 5 between the uranium-containing waste water and LME. The calculation results of Gibbs free energy show that the reaction process is spontaneous. (authors)

Optimization of the recycling process of precipitation barren solution in a uranium mine

International Nuclear Information System (INIS)

Long Qing; Yu Suqin; Zhao Wucheng; Han Wei; Zhang Hui; Chen Shuangxi

2014-01-01

Alkaline leaching process was adopted to recover uranium from ores in a uranium mine, and high concentration uranium solution, which would be later used in precipitation, was obtained after ion-exchange and elution steps. The eluting agent consisted of NaCl and NaHCO 3 . Though precipitation barren solution contained as high as 80 g/L Na 2 CO 3 , it still can not be recycled due to presence of high Cl - concentration So, both elution and precipitation processes were optimized in order to control the Cl - concentration in the precipitation barren solution to the recyclable concentration range. Because the precipitation barren solution can be recycled by optimization, the agent consumption was lowered and the discharge of waste water was reduced. (authors)

Solubility Limits of Dibutyl Phosphoric Acid in Uranium Solutions at SRS

International Nuclear Information System (INIS)

Thompson, M.C.; Pierce, R.A.; Ray, R.J.

1998-06-01

The Savannah River Site has enriched uranium (EU) solution which has been stored for almost 10 years since being purified in the second uranium cycle of the H area solvent extraction process. The concentrations in solution are 6 g/L U and about 0.1 M nitric acid. Residual tributylphosphate in the solutions has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 50 mg/L. Uranium is known to form compounds with DBP which have limited solubility. The potential to form uranium-DBP solids raises a nuclear criticality safety issue. SRTC tests have shown that U-DBP solids will precipitate at concentrations potentially attainable during storage of enriched uranium solutions. Evaporation of the existing EUS solution without additional acidification could result in the precipitation of U-DBP solids if DBP concentration in the resulting solution exceeds 110 ppm at ambient temperature. The same potential exists for evaporation of unwashed 1CU solutions. The most important variables of interest for present plant operations are HNO 3 and DBP concentrations. Temperature is also an important variable controlling precipitation. The data obtained in these tests can be used to set operating and safety limits for the plant. It is recommended that the data for 0 degrees C with 0.5 M HNO 3 be used for setting the limits. The limit would be 80 mg/L which is 3 standard deviations below the average of 86 observed in the tests. The data shows that super-saturation can occur when the DBP concentration is as much as 50 percent above the solubility limit. However, super-saturation cannot be relied on for maintaining nuclear criticality safety. The analytical method for determining DBP concentration in U solutions was improved so that analyses for a solution are accurate to within 10 percent. However, the overall uncertainty of results for periodic samples of the existing EUS solutions was only reduced slightly. Thus, sampling appears to be the largest portion

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

International Nuclear Information System (INIS)

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

1983-01-01

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

RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION

International Nuclear Information System (INIS)

Lascola, R

2008-01-01

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

Study on removing nitrate from uranium solution by ion-exchange method

International Nuclear Information System (INIS)

Zhou Genmao

2004-01-01

Nitrate of low concentration can interfere with adsorption of uranyl sulfate anion on anion-exchange resins because the anion-exchange resins have a stronger affinity for nitrate in uranium solution. Nitrate can be adsorbed with a high efficiency resin, then desorbed by sodium hydroxide. The nitrate concentration is about 60 g/L in eluate. The research results show that nitrate can be recovered from uranium solution with N-3 anion-exchange resin

Study of uranium (VI) in carbonate solution by potentiometric titrations and ion-exchange

International Nuclear Information System (INIS)

Billon, A.

1968-04-01

The present work is devoted to the fixation of uranium (VI) on the conventional anion-exchange resin Dowex 2 X 8 in carbonate and hydrogen-carbonate media. Both media were successfully used for the recuperation of uranium (VI) from very dilute solutions. Equilibrium constant of the exchange [UO 2 (CO 3 ) 3 4+ ] S + 2 [CO 3 2- ] R ↔ [UO 2 (CO 3 ) 3 4- ] R + 2[CO 3 2- ] S is determined for carbonate concentration range 0.1 M to 0.6 M from partition curves. A markedly increase in the relative fixation of uranium results with: - increasing free carbonate concentration of the solution, - decreasing uranium concentration. A study in the same conditions of the fixation of molybdenum has made it possible to separate the latter from uranium by elution, the carbonate concentration being molar. It is suggested a possibility of separation on a larger scale, based upon molybdenum displacement by uranium in hydrogen-carbonate medium. (author) [fr

The determination of phosphorus in uranium minerals and resulting solutions

International Nuclear Information System (INIS)

Petrement Eguiluz, J. C.; Parellada Bellod, R.; Fernandez Cellini, R.

1964-01-01

Interferences of several elements present in Spanish uranium minerals in the phosphorus determination by the spectrophotometrical method of the molibdovanada te phosphoric acid are studied. A method is described with a previous separation of these element by a cationic resin. This method is successfully applied to the phosphorus determination in acid or alkaline lixiviation solutions of uranium minerals, as well as in the evaluates of ion exchange resins used used technically for the concentration of solutions with a low uranium content. (Author) 11 refs

The conditions for uranium concentration in the phosphates of Tchivoula, Congo

International Nuclear Information System (INIS)

Giresse, P.; N'Landou, J. de Dieu; Wiber, M.

1986-01-01

The processes of deposition of marine phosphates in the Maastrichtian seas of the Congo do not appear capable alone of having produced the significant concentrations of uranium found. Diagenetic phenomena resulted in a mobilisation and a secondary concentration of uranium in the interior of recrystallized apatites. This secondary uranium may have been derived from the residual organic matrix in the deposit. Towards the top of the beds, hydrolysis of the apatites and authigenesis of crandallite, barrandite and ferruginous variscite led to uranium concentrations which are characteristic of alteration in a tropical climate. In contrast, wavellite, the final product of supergene alteration does not retain uranium. In the case of the Tchivoula deposits, the overlying Paleocene beds may have been the source of the uraniferous solutions' downslope movement which favored concentration in the underlying sediments. (orig.)

Field evaporation test of uranium tailings solution

International Nuclear Information System (INIS)

Chandler, B.L.; Shepard, T.A.; Stewart, T.A.

1985-01-01

A field experiment was performed to observe the effect on evaporation rate of a uranium tailings impoundment pond water as salt concentration of the water increased. The duration of the experiment was long enough to cause maximum salt concentration of the water to be attained. The solution used in the experiment was tailings pond water from an inactive uranium tailings disposal site in the initial stages of reclamation. The solution was not neutralized. The initial pH was about 1.0 decreasing to a salt gel at the end of the test. The results of the field experiment show a gradual and slight decrease in evaporation efficiency. This resulted as salt concentrations increased and verified the practical effectiveness of evaporation as a water removal method. In addition, the physical and chemical nature of the residual salts suggest that no long-term stability problem would likely result due to their presence in the impoundment during or after reclamation

Continuous measurement of uranium concentrations with the laser spark

International Nuclear Information System (INIS)

Gutmacher, R.G.; Cremers, D.A.; Wachter, J.R.

1987-01-01

Laser-induced breakdown spectroscopy has been applied to the continuous determination of uranium concentrations between 0.1 and 300 g/L in flowing solutions. The technique is rapid, noninvasive, and unaffected by radioactivity. A concentration of 10 g/L was measured with 0.8% precision in 3 min. Substances that absorb at the laser wavelength, suspended materials, and variations in the acidity of the solution have little or no effect on the results. High concentrations of zirconium, cadmium, aluminum, or stainless steel in solution do not interfere

Precipitation behavior of uranium in multicomponent solution by oxalic acid

International Nuclear Information System (INIS)

Shin, Y.J.; Kim, I.S.; Lee, W.K.; Shin, H.S.; Ro, S.G.

1996-01-01

A study on the precipitation of uranium by oxalic acid was carried out in a multicomponent solution. The precipitation method is usually applied to the treatment of radioactive waste and the recovery of uranium from a uranium-scrap contaminated with impurities. In these cases, the problem is how to increase the precipitation yield of target element and to prevent impurities from coprecipitation. The multicomponent solution in the present experiment was prepared by dissolving U, Nd, Cs and Sr in nitric acid. The effects of concentrations of oxalic acid and ascorbic acid on the precipitation yield and purity of uranium were observed. As results of the study, the maximum precipitation yield of uranium is revealed to be about 96.5% and the relative precipitation ratio of Nd, Cs and Sr versus uranium are discussed at the condition of the maximum precipitation yield of uranium, respectively. (author). 11 refs., 5 figs., 1 tab

Radium and uranium concentrations and associated hydrogeochemistry in ground water in southwestern Pueblo County, Colorado

Science.gov (United States)

Felmlee, J. Karen; Cadigan, Robert Allen

1979-01-01

Radium and uranium concentrations in water from 37 wells tapping the aquifer system of the Dakota Sandstone and Purgatoire Formation in southwestern Pueblo County, Colorado, have a wide range of values and define several areas of high radioactivity in the ground water. Radium ranges from 0.3 to 420 picocuries per liter and has a median value of 8.8, and uranium ranges from 0.02 to 180 micrograms per liter and has a median value of 2.4. Radon concentrations, measured in 32 of the 37 wells, range from less than 100 picocuries per liter to as much as 27,000 and have a median value of 580. Relationships among the radioactive elements and 28 other geochemical parameters were studied by using correlation coefficients and R-mode factor analysis. Five factor groups were determined to represent major influences on water chemistry: (1) short-term solution reactions, (2) oxidation reactions, (3) hydrolysis reactions, (4) uranium distribution, and (5) long-term solution reactions. Uranium concentrations are most strongly influenced by oxidation reactions but also are affected by solution reactions and distribution of uranium in the rocks of the aquifer system. Radon and radium concentrations are mostly controlled by uranium distribution; radium also shows a moderate negative relationship with oxidation. To explain the statistical and spatial relationships among the parameters, a model was developed involving the selective leaching of uranium-bearing phases and metal sulfides which occur in discontinuous zones in sandstone and shale. When reducing conditions prevail, uranium is immobile, but radium can be taken into solution. When faults and associated fractured rocks allow oxidizing conditions to dominate, uranium can be taken into solution; radium can also be taken into solution, or it may become immobilized by coprecipitation with iron and manganese oxides or with barite. Several areas within the study area are discussed in terms of the model.

Recovery of uranium from analytical waste solution

International Nuclear Information System (INIS)

Kumar, Pradeep; Anitha, M.; Singh, D.K.

2016-01-01

Dispersion fuels are considered as advance fuel for the nuclear reactor. Liquid waste containing significant quantity of uranium gets generated during chemical characterization of dispersion fuel. The present paper highlights the effort in devising a counter current solvent extraction process based on the synergistic mixture of D2EHPA and Cyanex 923 to recover uranium from such waste solutions. A typical analytical waste solution was found to have the following composition: U 3 O 8 (∼3 g/L), Al: 0.3 g/L, V: 15 ppm, Phosphoric acid: 3M, sulphuric acid : 1M and nitric acid : 1M. The aqueous solution is composed of mixture of either 3M phosphoric acid and 1M sulphuric acid or 1M sulphuric acid and 1M nitric acid, keeping metallic concentrations in the above mentioned range. Different organic solvents were tested. Based on the higher extraction of uranium with synergistic mixture of 0.5M D2EHPA + 0.125M Cyanex 923, it was selected for further investigation in the present work

Uranium chemistry in stack solutions and leachates of phosphogypsum disposed at a coastal area in Cyprus.

Science.gov (United States)

Lysandrou, M; Pashalidis, I

2008-02-01

The effect of the matrix composition (main constituents) on the concentration and chemical behavior of uranium in phosphogypsum stack solutions and leachates has been investigated. Solid and aqueous samples were taken from three different sub-areas of a phosphogypsum stack at a coastal area in Vasilikos (Cyprus). The sub-areas are characterized whether by their acidity (e.g. "aged" and "non-aged" phosphogypsum) or by their salt content, originating from pulping water during wet stacking or (after deposition) from the adjacent sea. Measurements in stack solutions and leachates showed that phosphogypsum characteristics affect both, the concentration and the chemical behavior of uranium in solution. Uranium concentration in solutions of increased salinity is up to three orders of magnitude higher than in solutions of low salinity and this is attributed to the effect of ionic strength on the solubility of phosphogypsum. Modelling showed that uranium in stack solutions is predominantly present in the form of uranium(VI) phosphate complexes (e.g. UO(2)(H(2)PO(4))(2), UO(2)HPO(4)), whereas in leachates uranium(VI) fluoro complexes (e.g. UO(2)F(2), UO(2)F(3)(-)) are predominant in solution. The latter indicates that elution of uranium from phosphogypsum takes places most probably in the form of fluoro complexes. Both, effective elution by saline water and direct migration of uranium to the sea, where it forms very stable uranium(VI) carbonato complexes, indicate that the adjacent sea will be the final receptor of uranium released from Vasilikos phosphogypsum.

Study of uranium (VI) in carbonate solution by potentiometric titrations and ion-exchange; Etude des solutions d'uranium (VI) en milieu carbonate par titrages potentiometriques et echange d'ions

Energy Technology Data Exchange (ETDEWEB)

Billon, A [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-04-01

The present work is devoted to the fixation of uranium (VI) on the conventional anion-exchange resin Dowex 2 X 8 in carbonate and hydrogen-carbonate media. Both media were successfully used for the recuperation of uranium (VI) from very dilute solutions. Equilibrium constant of the exchange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} is determined for carbonate concentration range 0.1 M to 0.6 M from partition curves. A markedly increase in the relative fixation of uranium results with: - increasing free carbonate concentration of the solution, - decreasing uranium concentration. A study in the same conditions of the fixation of molybdenum has made it possible to separate the latter from uranium by elution, the carbonate concentration being molar. It is suggested a possibility of separation on a larger scale, based upon molybdenum displacement by uranium in hydrogen-carbonate medium. (author) [French] Le present travail precise la fixation de l'uranium (VI) sur la resine echangeuse d'anions Dowex 2 X 8, en milieu carbonate et hydrogeno-carbonate. Nous en avons deduit que ces deux milieux sont egalement favorables a la recuperation de l'uranium a partir de solutions tres diluees. La constante d'equilibre de la reaction d'echange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} a ete determinee pour le milieu carbonate 0.1 M a 0.6 M, a partir deb courbes de partage. La fixation relative de l'uranium augmente considerablement lorsque: - la concentration du carbonate libre (respectivement hydrogenocarbonate) diminue, - la concentration de l'uranium en solution diminue. Le comportement du molybdene a ete etudie en vue de la separation uranium-molybdene. L'ion fixe sur la resine est l'ion molybdate MoO{sub 4}{sup 2-}. La separation est

Composition and method for solution mining of uranium ores

International Nuclear Information System (INIS)

Lawes, B.C.; Watts, J.C.

1981-01-01

It has been found that, in the solution mining of uranium ores using ammonium carbonate solutions containing hydrogen peroxide or ozone as an oxidant, the tendency of the formation being treated to become less permeable during the leaching process can be overcome by including in the leaching solution a very small concentration of sodium silicate

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-10-15

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

Determination of uranium in aqueous solutions by HPLC post column UV/VIS detection

International Nuclear Information System (INIS)

Abbasi, W.A.; Street, M.

1995-01-01

Analysis of uranium in different nitric acid concentration solutions is interest in nuclear industry where it is present in various process and waste streams. A method for the determination of uranium(VI) in nitric acid solution in described using ion chromatography and post-column derivatization with 4-(2-pyridylazo) resorcinol (PAR). The method does not require any sample treatment for acid removal or neutralization and can be used for routine laboratory analysis. The effluent used was ammonium sulphate / sulphuric acid and PAR was present in ammonium hydroxide/acetic acid buffer. The column effluents is reacted with PAR in a reaction coil and U(VI)-PAR complex is detector at 528 nm. The lowest uranium concentration detected was 100 ppb (0.1 mg/sup -1/) and linearity of up to 8 mgl -1 concentration was verified. The standard deviation in reproducibility at uranium concentration of 0.1 mgl/sup -1/ was 0.82%. (author)

Application of solution-mineral equilibrium chemistry to solution mining of uranium ores

International Nuclear Information System (INIS)

Riese, A.C.; Propp, C.J.

1980-01-01

Modern methods of uranium solution mining are typically accompanied by gains and losses of mass through reagent consumption by rock-forming minerals, with subsequent formation of clay minerals, gypsum, carbonates, and iron oxyhydroxides. A systematic approach to alleviate such problems involves the application of leach solutions that are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals. This partial equilibrium can be approximated by solution-composition adjustments within the systems K 2 O-Al 2 O 3 SiO 2 -H 2 O and Na 2 O 3 -Al 2 O 3 SiO 2 -H 2 O. Uranium ore containing 0.15 percent U 3 O 8 from the Gulf Mineral Resources Corporation's Mariano Lake mine, the Smith Lake district of the Grants mineral belt, was collected for investigation. Presented are a theoretical evaluation of leachate data and an experimental treatment of the ore, which contained mainly K-feldspar, plagioclase feldspar, and quartz (with lesser amounts of micas, clay minerals, and organic carbonaceous material). Small-scale (less than or equal to 1 kg) column-leaching experiments were conducted to model the results of conventional leaching operations and to provide leachate solutions that could be compared with solutions calculated to be in equilibrium with the matrix minerals. Leach solutions employed include: 1) sulfuric acid, 2) sodium bicarbonate, and 3) sulfuric acid with 1.0 molal potassium chloride. The uranium concentrations in the sodium-bicarbonate leach solution and the acid-leach solution were about a gram per liter at the termination of the tests. However, the permeability of the ore in the acid leach was greatly reduced, owing to the formation of clay minerals. Uranium solubility in the leach column stabilized with the potassium-chloride solution was calculated from leachate compositions to be limited by the solubility of carnotite

Bioprecipitation of uranium from alkaline waste solutions using recombinant Deinococcus radiodurans

Energy Technology Data Exchange (ETDEWEB)

Kulkarni, Sayali; Ballal, Anand; Apte, Shree Kumar, E-mail: aptesk@barc.gov.in

2013-11-15

Highlights: • Deinococcus radiodurans was genetically engineered to overexpress alkaline phosphatase (PhoK). • Deino-PhoK bioprecipitated U efficiently over a wide range of input U concentration. • A maximal loading of 10.7 g U/g of biomass at 10 mM input U was observed. • Radioresistance and U precipitation by Deino-PhoK remained unaffected by γ radiation. • Immobilization of Deino-PhoK facilitated easy separation of precipitated U. -- Abstract: Bioremediation of uranium (U) from alkaline waste solutions remains inadequately explored. We engineered the phoK gene (encoding a novel alkaline phosphatase, PhoK) from Sphingomonas sp. for overexpression in the radioresistant bacterium Deinococcus radiodurans. The recombinant strain thus obtained (Deino-PhoK) exhibited remarkably high alkaline phosphatase activity as evidenced by zymographic and enzyme activity assays. Deino-PhoK cells could efficiently precipitate uranium over a wide range of input U concentrations. At low uranyl concentrations (1 mM), the strain precipitated >90% of uranium within 2 h while a high loading capacity of around 10.7 g U/g of dry weight of cells was achieved at 10 mM U concentration. Uranium bioprecipitation by Deino-PhoK cells was not affected in the presence of Cs and Sr, commonly present in intermediate and low level liquid radioactive waste, or after exposure to very high doses of ionizing radiation. Transmission electron micrographs revealed the extracellular nature of bioprecipitated U, while X-ray diffraction and fluorescence analysis identified the precipitated uranyl phosphate species as chernikovite. When immobilized into calcium alginate beads, Deino-PhoK cells efficiently removed uranium, which remained trapped in beads, thus accomplishing physical separation of precipitated uranyl phosphate from solutions. The data demonstrate superior ability of Deino-PhoK, over earlier reported strains, in removal of uranium from alkaline solutions and its potential use in

Study of uranium (VI) in carbonate solution by potentiometric titrations and ion-exchange; Etude des solutions d'uranium (VI) en milieu carbonate par titrages potentiometriques et echange d'ions

Energy Technology Data Exchange (ETDEWEB)

Billon, A. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-04-01

The present work is devoted to the fixation of uranium (VI) on the conventional anion-exchange resin Dowex 2 X 8 in carbonate and hydrogen-carbonate media. Both media were successfully used for the recuperation of uranium (VI) from very dilute solutions. Equilibrium constant of the exchange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} is determined for carbonate concentration range 0.1 M to 0.6 M from partition curves. A markedly increase in the relative fixation of uranium results with: - increasing free carbonate concentration of the solution, - decreasing uranium concentration. A study in the same conditions of the fixation of molybdenum has made it possible to separate the latter from uranium by elution, the carbonate concentration being molar. It is suggested a possibility of separation on a larger scale, based upon molybdenum displacement by uranium in hydrogen-carbonate medium. (author) [French] Le present travail precise la fixation de l'uranium (VI) sur la resine echangeuse d'anions Dowex 2 X 8, en milieu carbonate et hydrogeno-carbonate. Nous en avons deduit que ces deux milieux sont egalement favorables a la recuperation de l'uranium a partir de solutions tres diluees. La constante d'equilibre de la reaction d'echange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} a ete determinee pour le milieu carbonate 0.1 M a 0.6 M, a partir deb courbes de partage. La fixation relative de l'uranium augmente considerablement lorsque: - la concentration du carbonate libre (respectivement hydrogenocarbonate) diminue, - la concentration de l'uranium en solution diminue. Le comportement du molybdene a ete etudie en vue de la separation uranium-molybdene. L'ion fixe sur la resine est l

Uranium concentrations in groundwater, northeastern Washington

Science.gov (United States)

Kahle, Sue C.; Welch, Wendy B.; Tecca, Alison E.; Eliason, Devin M.

2018-04-18

A study of uranium in groundwater in northeastern Washington was conducted to make a preliminary assessment of naturally occurring uranium in groundwater relying on existing information and limited reconnaissance sampling. Naturally occurring uranium is associated with granitic and metasedimentary rocks, as well as younger sedimentary deposits, that occur in this region. The occurrence and distribution of uranium in groundwater is poorly understood. U.S. Environmental Protection Agency (EPA) regulates uranium in Group A community water systems at a maximum contaminant level (MCL) of 30 μg/L in order to reduce uranium exposure, protect from toxic kidney effects of uranium, and reduce the risk of cancer. However, most existing private wells in the study area, generally for single family use, have not been sampled for uranium. This document presents available uranium concentration data from throughout a multi-county region, identifies data gaps, and suggests further study aimed at understanding the occurrence of uranium in groundwater.The study encompasses about 13,000 square miles (mi2) in the northeastern part of Washington with a 2010 population of about 563,000. Other than the City of Spokane, most of the study area is rural with small towns interspersed throughout the region. The study area also includes three Indian Reservations with small towns and scattered population. The area has a history of uranium exploration and mining, with two inactive uranium mines on the Spokane Indian Reservation and one smaller inactive mine on the outskirts of Spokane. Historical (1977–2016) uranium in groundwater concentration data were used to describe and illustrate the general occurrence and distribution of uranium in groundwater, as well as to identify data deficiencies. Uranium concentrations were detected at greater than 1 microgram per liter (μg/L) in 60 percent of the 2,382 historical samples (from wells and springs). Uranium concentrations ranged from less than 1 to

Evaluation of neutralization treatment processes and their use for uranium tailings solutions

International Nuclear Information System (INIS)

Sherwood, D.R.; Opitz, B.E.; Serne, R.J.

1985-01-01

The potential for groundwater contamination from the typically acidic mill wastes that are disposed of in tailings impoundments is of primary concern at uranium mill sites in the US. Solution-treatment processes provide a system for limiting the environmental impact from acidic seepage. Treatment of uranium tailings solutions from evaporation ponds, underdrains, and surface seeps could aid in decommissioning active sites or be used as an emergency measure to avert possible uncontrolled discharges. At present, neutralization processes appear to be best suited for treating uranium mill tailings solution because they can, at a reasonable cost, limit the solution concentration of many contaminants and thus reduce the potential for groundwater contamination. However, the effectiveness of the neutralization process depends on the reagent used as well as the chemistry of the waste stream. This article provides a description of neutralization processes, an assessment of their performance on acidic uranium tailings leachates, and recommendations for their use at US uranium mill sites

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

International Nuclear Information System (INIS)

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

1974-01-01

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

Calibration of uranium 232 solution

International Nuclear Information System (INIS)

Galan, M.P.; Acena, M.L.

1988-01-01

A method for acertainning the activity by alpha spectroscopy with semiconductor detectors, of a solution of Uranium-232 is presented. It consists of the comparison with a Uranium-233 solution activity previously measured in a gridded ionization chamber of 2 π geometry. The total measurement uncertainty is about +- 0,02. (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)

Behaviour of the pH adjustment, Ion exchange and concentrate precipitation stages in the acid leaching of uranium phosphate ores

International Nuclear Information System (INIS)

Estrada Aguilar, J.; Uriarte Hueda, A.

1962-01-01

The uranium recovery from acid leach solutions of uranium-phosphate ores has been studied. Relations have been found between the solution characteristics and the results obtained at different stages of the process. The following data can thus be predicted: solids to remove and uranium recovery in the pH adjustment stage, uranium capacity of the resin, more suitable eluating agent, elution velocity and uranium concentration in the eluate in the ion exchange stage, and composition of the concentrate produced by direct precipitation of the eluate in the concentrate precipitation stage. (Author) 8 refs

An investigation to compare the performance of methods for the determination of free acid in highly concentrated solutions of plutonium and uranium nitrate

International Nuclear Information System (INIS)

Crossley, D.

1980-08-01

An investigation has been carried out to compare the performance of the direct titration method and the indirect mass balance method, for the determination of free acid in highly concentrated solutions of uranium nitrate and plutonium nitrate. The direct titration of free acid with alkali is carried out in a fluoride medium to avoid interference from the hydrolysis of uranium or plutonium, while free acid concentration by the mass balance method is obtained by calculation from the metal concentration, metal valency state, and total nitrate concentration in a sample. The Gran plot end-point prediction technique has been used extensively in the investigation to gain information concerning the hydrolysis of uranium and plutonium in fluoride media and in other complexing media. The use of the Gran plot technique has improved the detection of the end-point of the free acid titration which gives an improvement in the precision of the determination. The experimental results obtained show that there is good agreement between the two methods for the determination of free acidity, and that the precision of the direct titration method in a fluoride medium using the Gran plot technique to detect the end-point is 0.75% (coefficient of variation), for a typical separation plant plutonium nitrate solution. The performance of alternative complexing agents in the direct titration method has been studied and is discussed. (author)

Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle

International Nuclear Information System (INIS)

Fang Chao; Cao Jianzhu; Sun Lifeng

2011-01-01

The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (UO 2 ) particle is built. The adsorption effect of the fission product on the surface of the UO 2 particle and the delayed decay effect are also considered. The solution is given in terms of Mittag-Leffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor. (nuclear physics)

High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

International Nuclear Information System (INIS)

Sunder, S.; McEachern, R.; LeBlanc, J.C.

2001-01-01

Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% CO 2 in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (authors)

Nitrification and in-situ uranium solution mining

International Nuclear Information System (INIS)

Johnson, D.; Humenick, M.J.

1980-01-01

The objective of this research was to determine the potential for conversion of ammonia to nitrate as a result of uranium solution mining operations. The work included literature evaluation and laboratory experimentation in both batch and continuous systems. Results indicate that a potential for nitrification could exist for some portions of the solution mining operating cycle. However, inhibition of nitrification was observed due to high ammonia and peroxide concentrations. Nitrification of ammonia also was observed to occur due to chemical oxidation by peroxide. 28 refs

Concentration of uranium in seawater by flotation

International Nuclear Information System (INIS)

Nozaki, Toru; Yamashita, Hiroshi

1986-01-01

A method has been developed for the concentration of uranium in seawater by precipitation flotation-carbonate extraction-ion flotation. Uranium in seawater was coprecipitated with hydrated iron (III) oxide by adjusting the pH to 5.5 after addition of 1.0 x 10 -3 mol/l of iron (III) and agitating for 1 hr, and the precipitate was floated with 1.0 x 10 -5 mol/l of sodium oleate and 5.0 x 10 -5 mol/l of sodium lauryl sulfate by bubbling nitrogen through the seawater for 15 min. Uranium was extracted from the precipitate scum at the yield of 89 % with 100 ml of 1.8 % of ammonium carbonate solution by agitating for 2 hr, and floated with 1.2 x 10 -3 mol/l of cetylpyridinium chloride by bubbling nitrogen through the extract diluted 5-fold for 30 min in the recovery of about 100 %. The fairly selective recovery of uranium was obtained from 4 l of seawater at the yield of 87 % throughout the entire process. (author)

The concentrations of uranium in marine organisms

Energy Technology Data Exchange (ETDEWEB)

Matsuba, Mitsue; Ishii, Toshiaki; Nakahara, Motokazu; Nakamura, Ryoichi; Watabe, Teruhisa; Hirano, Shigeki [National Inst. of Radiological Sciences, Hitachinaka, Ibaraki (Japan). Laboratory for Radioecology

2000-07-01

Determination of uranium in sixty-one species of marine organisms was carried out by inductively coupled plasma mass spectrometry to obtain concentration factors and to estimate the internal radiation dose. The concentrations of uranium in soft tissues of marine animals were ranged from 0.077 to 5040 ng/g wet wt. Especially, the branchial heart of cephalopod molluscs showed the specific accumulation of uranium. The concentration factor of the branchial heart of Octopus vulgaris, which indicated the highest value, was calculated to be about 1.6 x 10{sup 3}, comparing with that (3.1 ng/ml) in coastal seawaters of Japan. The concentrations of uranium in hard tissues of marine invertebrates such as clam and sea urchin were similar to those in soft tissues. In contrast, hard tissues like bone, scale, fin, etc. of fishes showed much higher concentrations of uranium than soft tissues like muscle. The concentrations of uranium of twenty-two species of algae were ranged from 2 to 310 ng/g wet wt. Particularly, the brown alga Undaria pinnatifida showed the highest value of the uranium content in the algae and its concentration factor was calculated to be 10{sup 2}. (author)

The concentrations of uranium in marine organisms

International Nuclear Information System (INIS)

Matsuba, Mitsue; Ishii, Toshiaki; Nakahara, Motokazu; Nakamura, Ryoichi; Watabe, Teruhisa; Hirano, Shigeki

2000-01-01

Determination of uranium in sixty-one species of marine organisms was carried out by inductively coupled plasma mass spectrometry to obtain concentration factors and to estimate the internal radiation dose. The concentrations of uranium in soft tissues of marine animals were ranged from 0.077 to 5040 ng/g wet wt. Especially, the branchial heart of cephalopod molluscs showed the specific accumulation of uranium. The concentration factor of the branchial heart of Octopus vulgaris, which indicated the highest value, was calculated to be about 1.6 x 10 3 , comparing with that (3.1 ng/ml) in coastal seawaters of Japan. The concentrations of uranium in hard tissues of marine invertebrates such as clam and sea urchin were similar to those in soft tissues. In contrast, hard tissues like bone, scale, fin, etc. of fishes showed much higher concentrations of uranium than soft tissues like muscle. The concentrations of uranium of twenty-two species of algae were ranged from 2 to 310 ng/g wet wt. Particularly, the brown alga Undaria pinnatifida showed the highest value of the uranium content in the algae and its concentration factor was calculated to be 10 2 . (author)

Uranium concentration in fossils

International Nuclear Information System (INIS)

Okano, J.; Uyeda, C.

1988-01-01

Recently it is known that fossil bones tend to accumulate uranium. The uranium concentration, C u in fossils has been measured so far by γ ray spectroscopy or by fission track method. The authors applied secondary ion mass spectrometry, SIMS, to detect the uranium in fossil samples. The purpose of this work is to investigate the possibility of semi-quantitative analyses of uranium in fossils, and to study the correlation between C u and the age of fossil bones. The further purpose of this work is to apply SIMS to measure the distribution of C u in fossil teeth

Quantitative determination of uranium in organic solution by X-ray fluorescence

International Nuclear Information System (INIS)

Leyt, D.V. de; Colangelo, C.H.

1987-01-01

An X-ray fluorescent method for the determination of uranium in tributilphosphate-kerosene-nitriacid solution has been developed. Chemical properties of the matrix elements were studied in order to select a convenient procedure to determine samples and standards on the same way. The method avoids the destruction of the organic material and has proved to be very useful for the fast control of uranium concentration. (Author) [es

Study PWA8 resin for chromatographic uranium concentration

International Nuclear Information System (INIS)

Coceancigh, Herman; Ramella, J. L.; Marrero, Julieta; Jiménez Rebagliati, Raúl

2013-01-01

For many years nuclear industry have been using resins as filler of chromatographic columns. These methods are specific and give reliable results in different applications, for those reasons are extremely useful as separation process. Currently the nuclear industry is growing and this brings new issues such as the need of reduction of the amount of waste, the optimization of the production process and others that the chromatography could solve with great results. AMBERLITETM PWA8 resin is an anion exchange resin which can be used for the removal of uranium from drinking water. In addition to high exchange capacity, this resin has excellent physical stability and a wide range of pH in which is operational. With the idea of concentrating uranium from wastes solution as main goal we made different experiments to understand the AMBERLITETM PWA8 and obtain the most important characteristics like; pH working range; capacity; activation and elution procedures. These procedures were developed and optimized the capacity was determined using a batch experiment and we obtain that the maximum capacity is 882,5 U ug /resin gr at a pH of 4,2. Following on from these results chromatographic experiments were performed in which both were obtained the percentage of recovery and the concentration factor. The percent recovery (% R) calculated as the percentage ratio between the total mass and the load mass eluted (% R = eluted mass / total mass * 100) was 94% with a concentration factor of 5 times From these results it is intended to concentrate wastes solutions from the fuel cycle processes with two main goals: decreasing volume for storage and for future reusing of the uranium coming from production. (author)

Calibration of X-ray densitometers for the determination of uranium and plutonium concentrations in reprocessing input and product solutions

International Nuclear Information System (INIS)

Ottmar, H.; Eberle, H.; Michel-Piper, I.; Kuhn, E.; Johnson, E.

1985-11-01

In June 1985 a calibration exercise has been carried out, which included the calibration of the KfK K-Edge Densitometer for uranium assay in the uranium product solutions from reprocessing, and the calibration of the Hybrid K-Edge/K-XRF Instrument for the determination of total uranium and plutonium in reprocessing input solutions. The calibration measuremnts performed with the two X-ray densitometers are described and analyzed, and calibration constants are evaluated from the obtained results. (orig.)

Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

Energy Technology Data Exchange (ETDEWEB)

Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel; Tansel, Berrin

2013-09-05

ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperatures of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.

Root uptake of uranium (6) in solution by a higher plant: speciation in hydroponic solution, bioavailability, micro-localisation and biological effects induced

International Nuclear Information System (INIS)

Laroche, L.

2005-01-01

Uranium exists naturally in the environment, usually present in trace quantities. In soil solution and oxic conditions, uranium is present in the +VI oxidation state and forms a large number of inorganic and organic complexes. The exposure medium, an artificial soil solution, was designed in such a way as to control the uranium species in solution. The geochemical speciation code JCHESS was used to calculate the uranium aqueous species concentration and to define the domains of interest, each of them characterized by a limited number of dominant U species. These domains were defined as follows: pH 4.9 with uranyl ions as dominant species, pH 5.8 with hydroxyl complexes and pH 7 where carbonates play a major role. For each pH, short-duration (5 hours of exposure) well-defined laboratory experiments were carried out with Phaseolus vulgaris as plant model. The effect of competitive ions such as Ca 2+ or the presence of ligands such as phosphate or citrate on root assimilation efficiency was explored. Results have shown that uranium transfer was not affected by the presence of calcium, phosphate or citrate (but was decreased of 60% with citrate (10 μM) at pH 5.8) in our experimental conditions. Moreover, observation in Transmission Electronic Microscopy (TEM), equipped with an EDAX probe, have shown that uranium was associated with granules rich in phosphorus and that there were some chloroplast anomalies. Finally, the presence of uranium affects root CEC by reducing it and stimulates root elongation at low uranium concentrations (100 nM, 400 nM and 2 μM at pHs 4.9, 5.8 and 7 respectively) and inhibits it at high uranium concentrations. (author)

Recovery of uranium by a reverse osmosis process

International Nuclear Information System (INIS)

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

1980-01-01

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

The significance of zircon characteristic and its uranium concentration in evaluation of uranium metallogenetic prospect

International Nuclear Information System (INIS)

Li Yaosong; Zhu Jiechen; Xia Yuliang

1992-02-01

Zircon characteristic and its relation to uranium metallogenetic process have been studied on the basis of physics properties and chemical compositions. It is indicated that the colour of zircon crystal is related to uranium concentration; on the basis of method of zircon population type of Pupin J.P., the sectional plan of zircon population type has been designed, from which result that zircon population type of uranium-producing rock body is distributed mainly in second section, secondly in fourth section; U in zircon presents synchronous increase trend with Th, Hf and Ta; the uranium concentration in zircon from uranium-producing geologic body increases obviously and its rate of increase is more than that of the uranium concentration in rock; the period, in which uranium concentration in zircon is increased, is often related to better uranium-producing condition in that period of this area. 1785 data of the average uranium concentration in zircon have been counted and clear regularity has been obtained, namely the average uranium concentrations in zircon in rich uranium-producing area, rock, geologic body and metallogenetic zone are all higher than that in poor or no uranium-producing area, rock, geologic body and metallogenetic zone. This shows that the average uranium concentration in zircon within the region in fact reflects the primary uranium-bearing background in region and restricts directly follow-up possibility of uranium mineralization. On the basis of this, the uranium source conditions of known uranium metallogenetic zones and prospective provinces have been discussed, and the average uranium concentrations in zircon from magmatic rocks for 81 districts have been contrasted and graded, and some districts in which exploration will be worth doing further are put forward

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

Energy Technology Data Exchange (ETDEWEB)

Sprynskyy, Myroslav, E-mail: sprynsky@yahoo.com [Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun (Poland); Kovalchuk, Iryna [Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun (Poland); Institute of Adsorption and Problem of Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., 03164 Kyiv (Ukraine); Buszewski, Boguslaw [Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun (Poland)

2010-09-15

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

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

Science.gov (United States)

Sprynskyy, Myroslav; Kovalchuk, Iryna; Buszewski, Bogusław

2010-09-15

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

Root uptake of uranium (6) in solution by a higher plant: speciation in hydroponic solution, bioavailability, micro-localisation and biological effects induced; Transfert racinaire de l'uranium (6) en solution chez une plante superieure: speciation en solution hydroponique, prise en charge par la plante, microlocalisation et effets biologiques induits

Energy Technology Data Exchange (ETDEWEB)

Laroche, L

2005-01-15

Uranium exists naturally in the environment, usually present in trace quantities. In soil solution and oxic conditions, uranium is present in the +VI oxidation state and forms a large number of inorganic and organic complexes. The exposure medium, an artificial soil solution, was designed in such a way as to control the uranium species in solution. The geochemical speciation code JCHESS was used to calculate the uranium aqueous species concentration and to define the domains of interest, each of them characterized by a limited number of dominant U species. These domains were defined as follows: pH 4.9 with uranyl ions as dominant species, pH 5.8 with hydroxyl complexes and pH 7 where carbonates play a major role. For each pH, short-duration (5 hours of exposure) well-defined laboratory experiments were carried out with Phaseolus vulgaris as plant model. The effect of competitive ions such as Ca{sup 2+} or the presence of ligands such as phosphate or citrate on root assimilation efficiency was explored. Results have shown that uranium transfer was not affected by the presence of calcium, phosphate or citrate (but was decreased of 60% with citrate (10 {mu}M) at pH 5.8) in our experimental conditions. Moreover, observation in Transmission Electronic Microscopy (TEM), equipped with an EDAX probe, have shown that uranium was associated with granules rich in phosphorus and that there were some chloroplast anomalies. Finally, the presence of uranium affects root CEC by reducing it and stimulates root elongation at low uranium concentrations (100 nM, 400 nM and 2 {mu}M at pHs 4.9, 5.8 and 7 respectively) and inhibits it at high uranium concentrations. (author)

Determination of uranium in uranyl nitrate solutions of nuclear grade quality - Gravimetric method

International Nuclear Information System (INIS)

1990-01-01

This international Standard specifies a precise and accurate gravimetric method for determining the uranium content in uranyl nitrate product solutions of nuclear grade quality at concentrations above 100 g/l of uranium. Non-volatile impurities influence the accuracy of the method. Uranyl nitrate is converted into uranium octoxide (U 3 O 8 ) by ignition in air to constant mass at 900 deg. C ± 10 deg. C. Calculation of the uranium content in the sample using a gravimetric conversion factor which depends on the isotopic composition of the uranium. The isotopic composition is determined by mass spectrometry

Recovery of uranium from sulphate solutions containing molybdenum

International Nuclear Information System (INIS)

Weir, D.R.; Genik-Sas-Berezowsky, R.M.

1983-01-01

A process for recovering uranium from a sulphate solution containing dissolved uranium and molybdenum includes reacting the solution with ammonia (pH 8 to 10), the pH of the original solution must not exceed 5.5 and after the addition of ammonia the pH must not be in the vicinity of 7 for a significant time. The resultant uranium precipitate is relatively uncontaminated by molybdenum. The precipitate is then separated from the remaining solution while the pH is maintained within the stated range

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

International Nuclear Information System (INIS)

1980-01-01

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

Characterization of low concentration uranium glass working materials

Energy Technology Data Exchange (ETDEWEB)

Eppich, G. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wimpenny, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Leever, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Knight, K. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hutcheon, I. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ryerson, F. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-03-22

A series of uranium-doped silicate glasses were created at (Lawrence Livermore National Laboratory) LLNL, to be used as working reference material analogs for low uranium concentration research. Specifically, the aim of this effort was the generation of well-characterized glasses spanning a range of concentrations and compositions, and of sufficient homogeneity in uranium concentration and isotopic composition, for instrumentation research and development purposes. While the glasses produced here are not intended to replace or become standard materials for uranium concentration or uranium isotopic composition, it is hoped that they will help fill a current gap, providing low-level uranium glasses sufficient for methods development and method comparisons within the limitations of the produced glass suite. Glasses are available for research use by request.

Uranium concentrations in fossils measured by SIMS

International Nuclear Information System (INIS)

Uyeda, Chiaki; Okano, Jun

1988-01-01

Semiquantitative analyses of uranium in fossil bones and teeth were carried out by SIMS. The results show a tendency that uranium concentrations in the fossils increase with the ages of the fossils. It is noticed that fossil bones and teeth having uranium concentration of more than several hundred ppm are not rare. (author)

Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands.

Science.gov (United States)

Li, Peng; Zhun, Bao; Wang, Xuegang; Liao, PingPing; Wang, Guanghui; Wang, Lizhang; Guo, Yadan; Zhang, Weimin

2017-12-19

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 μmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.

Precipitation-filtering technology for uranium waste solution generated on washing-electrokinetic decontamination

Energy Technology Data Exchange (ETDEWEB)

Kim, Gye-Nam, E-mail: kimsum@kaeri.re.kr; Park, Uk-Ryang; Kim, Seung-Soo; Moon, Jei-Kwon

2015-05-15

Graphical abstract: A recycling process diagram for the volume reduction of waste solution generated from washing-electrokinetic decontamination. - Highlights: • A process for recycling a waste solution generated was developed. • The total metal precipitation rate by NaOH in a supernatant after precipitation was the highest at pH 9. • The uranium radioactivity in the treated solution upon injection of 0.2 g of alum was lower. • After drying, the volume of sludge was reduced to 35% of the initial sludge volume. - Abstract: Large volumes of uranium waste solution are generated during the operation of washing-electrokinetic decontamination equipment used to remove uranium from radioactive soil. A treatment technology for uranium waste solution generated upon washing-electrokinetic decontamination for soil contaminated with uranium has been developed. The results of laboratory-size precipitation experiments were as follows. The total amount of metal precipitation by NaOH for waste solution was highest at pH 11. Ca(II), K(I), and Al(III) ions in the supernatant partially remained after precipitation, whereas the concentration of uranium in the supernatant was below 0.2 ppm. Also, when NaOH was used as a precipitant, the majority of the K(I) ions in the treated solution remained. The problem of CaO is to need a long dissolution time in the precipitation tank, while Ca(OH){sub 2} can save a dissolution time. However, the volume of the waste solution generated when using Ca(OH){sub 2} increased by 8 mL/100 mL (waste solution) compared to that generated when using CaO. NaOH precipitant required lower an injection volume lower than that required for Ca(OH){sub 2} or CaO. When CaO was used as a precipitant, the uranium radioactivity in the treated solution at pH 11 reached its lowest value, compared to values of uranium radioactivity at pH 9 and pH 5. Also, the uranium radioactivity in the treated solution upon injection of 0.2 g of alum with CaO or Ca(OH){sub 2} was

Recovery of uranium mineral concentrate from copper tailings

International Nuclear Information System (INIS)

Chakravarty, S.; Tewari, U.K.; Beri, K.K.

1991-01-01

Based on the studies conducted on the samples of copper tailings from Surda Copper Concentrator plant, wet concentrating table (Diaster Diagonal Deck) was found most suitable for recovering uranium mineral concentrate. Based on this technique, uranium recovery plants were set up at Surda, Rakha and Mosabani. The recoveries obtained from Surda Uranium Recovery Plant and Rakha Uranium Recovery Plant were in the range of 40-50%. But in Mosaboni Uranium Recovery Plant which is treating copper tailings from Mosaboni Copper Concentrator Plant, the biggest concentrator plant processing nearly 2,700 MT/day of copper ore, the recovery by wet concentrating tables was found to be around 22%. Low recovery was mainly due to low concentration of uranium in ore and as well as more percentage of uranium distribution in fines which tables were unable to recover. Studies were done to recover uranium mineral concentrate from the fines with new set of equipment viz. Curved Static Screen/Bartles Mozley Separator/Cross Belt Concentrator. This gave an improvement of 14-16% only. Studies by low acid leaching in chemical process side have shown that an overall recovery of 68% can be achieved. Though the chemical process is best as far as recovery is concerned but there are several constraints. The major constraint is pertaining to environmental and pollution control. Depending on the results of studies to overcome the constraints decision for the process to be adopted will be taken up and executed. The test results and plant performance data have also been included in the paper. (author). 8 figs., 11 tabs., 1 appendix

Concentrations of uranium and thorium isotopes in uranium millers' and miners' tissues

International Nuclear Information System (INIS)

Wrenn, M.E.; Singh, N.P.; Paschoa, A.S.; Lloyd, R.D.; Saccomanno, G.

1985-09-01

The alpha-emitting isotopes of uranium and thorium were determined in the lungs of 14 former uranium miners and in soft tissues and bones of three miners and two millers. These radionuclides were also determined in soft tissues and bones of seven normal controls. The average concentrations in pCi/kg wet weight in 17 former miners' lungs are as follows: 238 U, 75; 234 U, 80; 230 Th, 79. Concentrations of each nuclide ranged from 2 to 325 pCi/kg. The average ratio of 238 U/ 234 U was 0.92, ranging from 0.64 to 1.06. The mean ratio of 230 Th/ 234 U was 1.04, ranging from 0.33 to 3.54. The near equilibrium between 230 Th and /sup 238,234/U indicates that the rate of elimination of uranium and thorium from lungs is the same in former uranium miners. The concentrations of 234 U and 238 U were highest in lung; however, the concentration of 230 Th in bones was either higher than or comparable to its concentration in lung. The concentration ratios of 230 Th/ 234 U in bone of uranium miners and millers measured in our laboratory have been compared with results predicted by ICRP-30 metabolic models. These results indicate that the ICRP metabolic models for thorium and uranium were only marginally successful in predicting the ratio of 230 Th/ 234 U in bones, and that effective release rate of uranium from skeleton may be more rapid than predicted by the ICRP model. 9 figs., 21 tabs

Sorption behaviour of uranium and thorium on cryptomelane-type hydrous manganese dioxide from aqueous solution

International Nuclear Information System (INIS)

El-Naggar, I.M.; El-Absy, M.A.; Abdel-Hamid, M.M.; Aly, H.F.

1993-01-01

The kinetics of sorption of uranium and thorium from aqueous nitrate solutions on cryptomelane-type hydrous manganese dioxide (CRYMO) was studied. The exchange of uranium is particle diffusion controlled while that of thorium is chemical reaction at the exchange sites. Sorption of uranium and thorium by CRYMO has been also studied as a function of metal concentrations and temperature. The sorption of both cations is found to be an endothermic process and increases markedly with temperature between 30 and 60 degree C. The sorption results have been analysed by the langmuir adsorption isotherm over the entire range of uranium and thorium concentrations investigated. 35 refs., 8 figs., 5 tabs

Uranium nanoparticle synthesis from leaching solution

International Nuclear Information System (INIS)

Sadowski, Z.; Sklodowska, A.

2014-01-01

The removal of uranium from leaching and bioleaching solutions is of great significance for an environment protection. In comparison with conventional separation techniques, synthesis of uranium nanoparticles has a number of benefits. It has been demonstrated that the uranium nanoparticles show high catalytic activity. In the present studies a variety of synthesis systems have been used for reduction of uranium from bioleaching solution. Among various catalytical templates the hematite Fe_2O_3 nanoparticles are most interest It was presented the report on development of synthesis method to produce nano structured Fe_2O_3 particles. The efficiency of hematite nanoparticles for adsorption of uranium ions from bioleaching solutions was investigated. Bacterial leaching is alternate technique used to extract uranium from mining wastes. The bioleaching process is environment friendly and gives the extraction yield of over 90%. The bioleaching solutions were obtained from bioleaching experiments using waste materials from different places at Lower Silesia (Kowary, Grzmiaca, Kopaniec, Radoniow). Chemoautotrophic bacteria were used for bioleaching tests. The significant adsorption capacity of U(VI) onto iron oxide and hydroxides (goethite, hematite, and magnetite) was observed. The sorption of U(VI) onto the hematite surface was connected with the chemical reduction of U(VI) to U(IV) by Fe"2"+ ions. The initial reaction system contained excess of Fe"2"+ ions which were used to reduce of U(VI). The reduction of U(VI) occurred at pH at the vicinity of pH=2.4. The colloid particles of hematite with UO_2 nanoparticles were obtained. The results of zeta potential measurements of hematite nanoparticles showed that at the ionic strength equals 10"-"3M NaCl, the average zeta potential was +32.4±3.5 mV at pH = 2.6. The interaction of hematite nanoparticles with the bioleaching solutions led to decrease of positive zeta potential to the value of 6.4± 2.7 mV. (author)

Recovery of uranium from the Syrian phosphate by solid-liquid method using alkaline solutions

International Nuclear Information System (INIS)

Shlewit, H.; Alibrahim, M.

2007-01-01

Uranium concentrations were analyzed in the Syrian phosphate deposits. Mean concentrations were found between 50 and 110 ppm. As a consequence, an average phosphate dressing of 22 kg/ha phosphate would charge the soil with 5-20 g/ha uranium when added as a mineral fertilizer. Fine grinding phosphate produced at the Syrian mines was used for uranium recovery by carbonate leaching. The formation of the soluble uranyl tricarbonate anion UO 2 (CO 3 ) 3 4- permits use of alkali solutions of sodium carbonate and sodium bicarbonate salts for the nearly selective dissolution of uranium from phosphate. Separation of iron, aluminum, titanium, etc., from the uranium during leaching was carried out. Formation of some small amounts of molybdates, vanadates, phosphates, aluminates, and some complexes metal was investigated. This process could be used before the manufacture of TSP fertilizer, and the final products would contain smaller uranium quantities. (author)

Simulation of effects of redox and precipitation on diffusion of uranium solution species in backfill

International Nuclear Information System (INIS)

Carnahan, C.L.

1987-12-01

This investigation addresses the problem of prediction of the rate of migration of redox-sensitive solution species within packing and backfill materials under conditions of variable oxidation potential. Effects of changes of oxidation potential and precipitation of stable uranium compounds during diffusion of uranium from a region of high oxidation potential into a region of low oxidation potential were simulated numerically. Questions of particular interest addressed in the investigation were the existence of a moving ''redox front'' and the influence of precipitation-dissolution processes on uranium migration. The simulations showed that no expanding redox fronts existed at any simulated time up to 3.2 x 10 5 years (10 13 s). In simulations where precipitation of stable solids was not allowed, variations of oxidation potential did not affect total uranium concentrations in solution. Concentration profiles could be predicted simply by diffusion of the (constant) source concentrations. In simulations where precipitation of stable solids was allowed, uraninite and calcium uranate accumulated at the source-transport domain interface, while coffinite penetrated further into the transport domain. Total uranium concentrations in regions of precipitation were determined by solubilities of the precipitated solids, and were six to seven orders of magnitude lower than those in the simulations without precipitation, throughout the domain of transport. 14 refs., 7 figs., 2 tabs

Evaluation of adsorption of uranium from aqueous solution using biochar materials

Energy Technology Data Exchange (ETDEWEB)

Correa, Wagner Clayton; Guilhen, Sabine Neusatz; Ortiz, Nilce; Fungaro, Denise Alves, E-mail: wcorrea@ipen.br, E-mail: snguilhen@ipen.br, E-mail: notriz@ipen.br, E-mail: dfungaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Uranium is present in the environment as a result of leaching from natural deposits and activities associated with nuclear fuel, copper mining, uranium mining, milling industry, etc. For the purpose of protecting ecosystem stability and public health, it is crucial to eliminate uranium from aqueous solutions before they are discharged into the environment. Various technologies have been used for removing U(VI) ions from aqueous systems. Among these methods, adsorption has been applied in wastewater because of simple operation procedure and high removal efficiency. Brazil is the largest producer of charcoal in the world, with nearly half of the woody biomass harvested for energy in Brazil being transformed into charcoal. Biochar exhibits a great potential as an adsorbent because of favorable physical/chemical surface characteristics. The objective of this work was to evaluate the adsorption potential of biochar materials prepared from pyrolysis of Bamboo (CBM), Eucalyptus (CEM) and Macauba (CMA) nuts for the removal of uranium from solutions. Adsorption experiments were carried out by a batch technique. Equilibrium adsorption experiments were performed by shaking a known amount of biochar material with 100 mL of U(VI) solution in Erlenmeyer flasks in a shaker at 120 rpm and room temperature (25 deg C) for 24 h. The adsorbent was separated by centrifugation from the solution. The U(VI) concentration remaining in the supernatant solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The influences of different experimental parameters such as solution pH and bioadsorbent dose on adsorption were investigated. The highest uranium adsorption capacity were obtained at pH 3.0 and 16 g/L biomass dosage for CMA, pH 3.0 and 12 g/L biomass dosage for CBM and pH 2.0 and 10 g/L biomass dosage for CEM. The results demonstrated that the biomass derived char can be used as a low-cost adsorbent for removal of uranium from wastewater. (author)

Evaluation of adsorption of uranium from aqueous solution using biochar materials

International Nuclear Information System (INIS)

Correa, Wagner Clayton; Guilhen, Sabine Neusatz; Ortiz, Nilce; Fungaro, Denise Alves

2015-01-01

Uranium is present in the environment as a result of leaching from natural deposits and activities associated with nuclear fuel, copper mining, uranium mining, milling industry, etc. For the purpose of protecting ecosystem stability and public health, it is crucial to eliminate uranium from aqueous solutions before they are discharged into the environment. Various technologies have been used for removing U(VI) ions from aqueous systems. Among these methods, adsorption has been applied in wastewater because of simple operation procedure and high removal efficiency. Brazil is the largest producer of charcoal in the world, with nearly half of the woody biomass harvested for energy in Brazil being transformed into charcoal. Biochar exhibits a great potential as an adsorbent because of favorable physical/chemical surface characteristics. The objective of this work was to evaluate the adsorption potential of biochar materials prepared from pyrolysis of Bamboo (CBM), Eucalyptus (CEM) and Macauba (CMA) nuts for the removal of uranium from solutions. Adsorption experiments were carried out by a batch technique. Equilibrium adsorption experiments were performed by shaking a known amount of biochar material with 100 mL of U(VI) solution in Erlenmeyer flasks in a shaker at 120 rpm and room temperature (25 deg C) for 24 h. The adsorbent was separated by centrifugation from the solution. The U(VI) concentration remaining in the supernatant solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The influences of different experimental parameters such as solution pH and bioadsorbent dose on adsorption were investigated. The highest uranium adsorption capacity were obtained at pH 3.0 and 16 g/L biomass dosage for CMA, pH 3.0 and 12 g/L biomass dosage for CBM and pH 2.0 and 10 g/L biomass dosage for CEM. The results demonstrated that the biomass derived char can be used as a low-cost adsorbent for removal of uranium from wastewater. (author)

Corrosion behavior of 321 stainless steel in low-acidity uranium nitrate solution

International Nuclear Information System (INIS)

Liao Junsheng; Sun Ying; Zhang Wanglin; Ding Ping; Yang Jiangrong; Wu Lunqiang

2003-01-01

Weighing and electrochemical methods have been used to investigate the high-temperature uniform corrosion and electrochemical corrosion behavior of lCr18Ni9Ti (321) stainless steel in uranium nitrate solution at different concentrations and pH values. The uniform corrosion results showed that the corrosion rate of 321 stainless steel was less than 0.04 g/m 2 .h, and the visible change of surface smoothness was not observed through 960 h. It was perfect corrosion-resisting in obtained conditions. The electro-chemical corrosion behavior study has been performed to investigate 321 stainless steel in uranium nitrate solutions of the dissolved and saturated oxygen. The corrosion potential and corrosion current density were obtained. Auger photoelectron spectroscopy for measurement of uranium in specimen was used to indicate that uranium is in corrosion product. The corrosion film was measured by Ar ion gun sputter, and the thickness is 10-15 nm. (authors)

Interpretation of criticality experiments on homogeneous solutions of plutonium and uranium; Interpretation des experiences de criticite sur des solutions homogenes de plutonium et d'uranium

Energy Technology Data Exchange (ETDEWEB)

Ithurralde, M F; Kremser, J; Leclerc, J; Lombard, Ch; Moreau, J; Robin, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Criticality experiments on solutions of fissionable materials have been carried out in tanks of various geometries (cylinder, isolated annular cylinder, interacting annular cylinders); the reflexion conditions have also been varied (without reflection, semi-reflection and total reflexion by water). The range of the studied concentrations is rather large (18,8 to 104 gms/liter). The interpretation of these experiments has been undertaken in order to resolve the problems of the industrial use of homogeneous plutonium and uranium solutions. Several methods the fields of application of which are different have been used: diffusion method, transport method and Monte-Carlo method. (authors) [French] Des experiences critiques sur des solutions de matieres fissiles ont ete faites dans des cuves de diverses geometries (cylindre, cylindre annulaire isole, cylindre annulaire en interaction), les conditions de reflexion ont ete egalement variees (sans reflexion, semi reflexion et reflexion totale par l'eau). La gamme des concentrations etudiees est assez etendue (18,8 a 104 g/l ). L'interpretation de ces experiences a ete entreprise dans le but de pouvoir resoudre les problemes poses par l'emploi industriel de solutions homogenes de plutonium et d'uranium, plusieurs methodes dont les domaines d'application sont differents ont ete employees: methode de diffusion, methode de transport, methode de Monte-Carlo. (auteurs)

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

Determination of microamounts of uranium in waste solutions

International Nuclear Information System (INIS)

Birringer, K.J.; Netzer, S.; Kuhn, E.; Groll, P.

1975-07-01

A method for the determination of microamounts of uranium in presence of high amounts of fission and corrosion products is described. Uranium is separated by reversed-phase chromatography on a small column, packed with Voltalef micro and impregnated with TOPO. For the direct photometric determination uranium is eluted by TAM dissolved in ethanol/pyridine. The efficiency of the separation, using a suitable scrub-solution, was tested with solutions of simulated inactive fission and corrosion products. The reproducibility of the method, with 24 μg of uranium, is +- 2,5%. (orig.) [de

Method of precipitating uranium from an aqueous solution and/or sediment

Science.gov (United States)

Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin

2013-08-20

A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

Fungi outcompete bacteria under increased uranium concentration in culture media

International Nuclear Information System (INIS)

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

2013-01-01

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

Influence of phosphates when uranium in solutions obtained by attacking Forez with sulfuric acid is precipitated by the action of lime; Influence des phosphates, lors de la precipitation par la chaux, de l'uranium contenu dans les solutions d'attaque sulfurique du Forez

Energy Technology Data Exchange (ETDEWEB)

Brebec, G

1959-03-01

Influence of phosphates when uranium in solutions obtained by attacking Forez with sulfuric acid is precipitated by the action of lime was studied. Most of the phosphates were eliminated in the form of ferric phosphates without noticeable losses of uranium: for this it is only necessary to add sufficient ferric sulfate to the solution to be treated so that [Po{sub 4}{sup 3-}]/[Fe{sup 3+}] {approx} 0,4. In these conditions, the preparation of a calcium concentrate rich in uranium takes place in two stages. The first is neutralization at pH 2,7 to 2,8 with elimination of phosphates, sulfates and iron; the second is precipitation of the concentrate at pH 6,5. (author) [French] Nous avons reussi a eliminer la majeure partie des phosphates sous forme de phosphates ferriques, sans pertes sensibles d'uranium. Pour cela, il suffit d'ajouter a la solution a traiter, du sulfate ferrique en quantite telle que: (Po{sub 4}{sup 3-}]/[Fe{sup 3+}] {approx} 0,4. Dans ces conditions, la preparation du concentre calcique, riche en uranium, s'effectue normalement en deux temps: 1) preneutralisation a pH 2,7-2,8: elimination des sulfates, phosphates et fer; 2) precipitation du concentre a pH 6,5. (auteur)

Determination of Ga in aqueous uranium solution by EDXRF

International Nuclear Information System (INIS)

Natarajan, V.; Purohit, P.J.; Goyal, Neelam; Seshagiri, T.K.; Godbole, S.V.; Manchanda, V.K.

2009-01-01

A method has been developed using EDXRF technique for the determination of gallium in aqueous solution using a set of solution standards in the concentration range 20-5000 μg/ml. When this method was applied to U containing solutions, the estimated values were found to be lower due to matrix effects. Hence the method was modified in order to determine gallium in the presence of uranium using lower tube current and another set of standards with U concentration at 100 mg/ml. The method was applicable for the estimation of Ga from 50 μg/ml to 5mg/ml (i.e.0.05-5% Ga in U). Three synthetic samples were analysed by the present methods in order to evaluate the method for its reliability and reproducibility. (author)

Determination of humic acid in alkali leaching solution of uranium by spectophotrometry-COD method

International Nuclear Information System (INIS)

Feng Yu; An Wei; Chen Shusen

2014-01-01

It is one of the main causes of extraction emulsification or resin toxicosis during alkali leaching process in uranium metallurgy which organic matters including humic acid exist in lixiviums. In order to study the effect of humic acid in uranium metallurgy, a method for determination of content of humic acid in aqueous solution need to be established. Spectrophotometry is a simple and convenient method in humic acid analysis. However, accuracy of spectrophotometry can be reduced greatly because of interference of uranium and other elements in the humic acid solutions. Although chemical oxygen demand (COD) method is a common analysis way of organic matters in aqueous solutions, the concentration of humic acid cannot be directly measured. In this paper, COD method is related with spectrophotometry to avoid the interference of uranium and ensure the accurate analysis of humic acid. The results showed that the detection limit of the method was 1.78 mg/L and the recovery rate was 101.2%. (authors)

Feasibility of Uranium Concentration Measurements for H Canyon Tank 16.7

International Nuclear Information System (INIS)

Lascola, R.J.

2003-01-01

Savannah River Technology Center (SRTC) evaluated the feasibility of using the H Canyon on-line diode array spectrophotometer to measure uranium concentrations in Tank 16.7. On-line measurements will allow an increase in highly enriched uranium (HEU) production by removing delays associated with off-line measurements. The instrument must be able to measure uranium at concentrations below 1.0 g/L with an uncertainty no greater than 0.3 g/L. SRTC determined that the system has a limit of quantitation of 0.15 g/L. At concentrations of 0.5 and 1.0 g/L, the spectrometer uncertainty is 0.10 g/L. No design changes, such as an increase in flow cell path length, are required to obtain this performance. Expected levels of iron in Tank 16.7 solutions will not interfere with the measurement. The CHEMCHEK method should not be used for confirmatory analysis, as it contributes excessively to the overall uncertainty of the measurement. SRTC expects that the spectrophotometer will meet the measurement requirements for Tank 16.7

Physicochemical aspects of extraction of uranium concentrate from the wastes and thermodynamic characteristics of thorium-uranium compounds

International Nuclear Information System (INIS)

Khamidov, F.A.

2017-01-01

The purpose of present work is elaboration of physicochemical aspects of extraction of uranium concentrate from the wastes and study of thermodynamic characteristics of thorium-uranium compounds. Therefore, the radiological monitoring of tailing dumps of Tajikistan has been conducted; the obtaining of uranium concentrate from the tailing dumps of uranium production has been studied; the obtaining of uranium concentrate from the tailing dumps of uranium production with application of local sorbents has been studied as well; thermal stability and thermodynamic characteristics of uranium-thorium compounds has been investigated; the flowsheets of extraction of uranium concentrate from the wastes have been elaborated.

Study of uranium(VI) speciation in phosphoric acid solutions and of its recovery by solvent extraction

International Nuclear Information System (INIS)

Dartiguelongue, Adrien

2014-01-01

Because small amounts of uranium are present in phosphate rocks, wet phosphoric acids may contain up to 300 ppm of uranium(VI). Therefore, such acids are a cost-effective unconventional source of this metal. Its recovery is a challenge for metallurgical firms which must develop reliable and selective solvent extraction processes. Such processes need to know the chemical equilibria involved in the extraction process, the speciation of uranium and its thermodynamics in solution. These two last points have been investigated in this work. Firstly, the most probable species of uranium(VI) in phosphoric acid solutions have been selected thanks to a detailed review of the literature. Then, a thermodynamic model founded on an equation of state for electrolytes has been built according these hypotheses. It has been validated with speciation data coming from original ATR-IR spectroscopy measurements. Finally, the composition of the aqueous phosphoric acid solutions and the activity coefficients obtained have been combined with a chemical model of uranium(VI) extraction into an organic phase containing a synergistic mixture of bis(2-ethylhexyl)phosphoric acid (D2EHPA) and tri-n-octylphosphine oxide (TOPO) in order to represent the variation of the distribution coefficient of uranium(VI) with H 3 PO 4 concentration. This model had been previously developed at Chimie ParisTech at a given concentration of H 3 PO 4 (i.e., 5,3 mol/L), but in the present study we have tested its validity in an extended range of phosphoric acid concentrations (i.e., 1-7 mol/L) and improved it. (author)

Effect of uranyl nitrate and free acid concentration in feed solution of gelation on UO2 kernel quality

International Nuclear Information System (INIS)

Masduki, B.; Wardaya; Widarmoko, A.

1996-01-01

An investigation on the effect of uranium and free nitric acid concentration of uranyl nitrate as feed of gelation process on quality of UO 2 kernel was done.The investigation is to look for some concentration of uranyl nitrate solutions those are optimum as feed for preparation of gelled UO 3 . Uranyl nitrate solution of various concentration of uranium (450; 500; 550; 600; 650; 700 g/l) and free nitric acid of (0.9; 1.0; 1.1 N) was made into feed solutions by adding urea and HMTA with mole ratio of urea/uranium and HMTA/uranium 2.1 and 2.0. The feed solutions were changed into spherical gelled UO 3 by dropping was done to get the optimum concentrations of uranyl nitrate solutions. The gelled UO 3 was soaked and washed with 2.5% ammonia solution for 17 hours, dried at 70 o C, calcined at 350 o C for 3 hours then reduced at 850 o C for 3 hours. At every step of the steps process the colour and percentage of well product of gelled UO 3 were noticed. The density and O/U ratio of end product (UO 2 kernel) was determined, the percentage of well product of all steps process was also determined. The three factor were used to chose the optimum concentration of uranyl nitrate solution. From this investigation it was concluded that the optimum concentration of uranyl nitrate was 600 g/l uranium with free nitric acid 0,9 - 1,0 N, the percentage of well product was 97% density of 6.12 - 4.8 g/cc and O/U ratio of 2.15 - 2.06. (author)

Fluorimetrich determination of uranium in mineral samples and phosphoric solutions

International Nuclear Information System (INIS)

Pupo Gonzales, I.; Cuevillas, J.; Estevez, J.

1991-01-01

In this paper an analytical technique for the determination of uranium in different cuban minerals and acid leaching liquors of phosphorites is proposed. The method used for solid samples includes their disolution and further dilution of the solution obtained. For liquid samples dilution is the only intermediate step used. A study of HNO3 concentration (pH) was made in fluorimetric measurements. The method was applied to the uranium analysis in two IAEA standard reference samples (phosphate base), in natural phosphorites and a synthetic one, in clays and phosphoric liquors. The results agree with those obtained by other methods

Uranium extraction from sulfuric acid solution using anion exchange resin

International Nuclear Information System (INIS)

Sheta, M. E.; Abdel Aal, M. M.; Kandil, A. T.

2012-12-01

Uranium is currently recovered from sulfuric acid leach liquor using anion exchange resin as Amberlite IRA 402 (CT). This technology is based on fact that, uranium exists as anionic complexes. This takes place by controlling the pH of the solution, agitation time, temperature and resin to solution ratio (R/S). In this work, batch stirrer tank used for uranium extraction from sulfate medium and after extraction, elution process was done using 1M NaCl solution. After extraction and elution process, the resin was separated from the system and uranium was determined in the solution. (Author)

Methods of Uranium Determination in solutions of Tributyl Phosphate and Kerosene

International Nuclear Information System (INIS)

Petrement Eguiluz, J.; Palomares Delgado, F.

1962-01-01

A new analytical method for the determination of uranium in organic solutions of tributyl phosphate and kerosene is proposed. In this method the uranium is reextracted from the aqueous phase by reduction with cadmium in acid solution. The uranium can be determined in this solution by the usual methods. In case of very diluted solutions, a direct spectrophtometrical determination of uranium in the organic phase with dibenzoylmethane is proposed. (Author) 21 refs

Potentiality of uranium biosorption from nitric acid solutions using shrimp shells.

Science.gov (United States)

Ahmed, S H; El Sheikh, E M; Morsy, A M A

2014-08-01

Biosorption has gained important credibility during recent years because of its good performance and low cost. This work is concerned with studying the potentiality of the chitin component of the shrimp shells for uranium biosorption from nitric acid liquid solutions. The structural characteristics of the working chitin have been determined via Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was examined using Scanning Electron Microscopy (SEM). The adsorption capacity of biomass was investigated experimentally. The influence of contact time, pH, metal ion concentration, solution volume to mass ratio and temperature were evaluated and the results were fitted using adsorption isotherm models. The kinetic of uranium biosorption was also investigated as well as biosorption thermodynamic. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recovery of uranium from uranium mine waters and copper ore leaching solutions

Energy Technology Data Exchange (ETDEWEB)

George, D R; Ross, J R [Salt Lake City Metallurgy Research Center, Salt Lake City, UT (United States)

1967-06-15

Waters pumped from uranium mines in New Mexico are processed by ion exchange to recover uranium. Production is approximately 200 lb U{sub 3}O{sub 8}/d from waters containing 5 to 15 ppm U{sub 3}O{sub 8}. Recoveries range from 80 to 90%. Processing plants are described. Uranium has been found in the solutions resulting from the leaching of copper-bearing waste rock at most of the major copper mines in western United States. These solutions, which are processed on a very large scale for recovery of copper, contain 2 to 12 ppm U{sub 3}O{sub 8}. Currently, uranium is not being recovered, but a potential production of up to 6000 lb U{sub 3}O{sub 8}/d is indicated. Ion exchange and solvent extraction research studies are described. (author)

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

International Nuclear Information System (INIS)

Othman, S.H.A.

2003-01-01

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

Solvent-extraction and purification of uranium(VI) and molybdenum(VI) by tertiary amines from acid leach solutions

International Nuclear Information System (INIS)

La Gamma, Ana M.G.; Becquart, Elena T.; Chocron, Mauricio

2008-01-01

Considering international interest in the yellow-cake price, Argentina is seeking to exploit new uranium ore bodies and processing plants. A study of similar plants would suggest that solvent- extraction with Alamine 336 is considered the best method for the purification and concentration of uranium present in leaching solutions. In order to study the purification of these leach liquors, solvent-extraction tests under different conditions were performed with simulated solutions which containing molybdenum and molybdenum-uranium mixtures. Preliminary extraction tests carried out on mill acid-leaching liquors are also presented. (authors)

Elevated Arsenic and Uranium Concentrations in Unregulated Water Sources on the Navajo Nation, USA.

Science.gov (United States)

Hoover, Joseph; Gonzales, Melissa; Shuey, Chris; Barney, Yolanda; Lewis, Johnnye

2017-01-01

Regional water pollution and use of unregulated water sources can be an important mixed metals exposure pathway for rural populations located in areas with limited water infrastructure and an extensive mining history. Using censored data analysis and mapping techniques we analyzed the joint geospatial distribution of arsenic and uranium in unregulated water sources throughout the Navajo Nation, where over 500 abandoned uranium mine sites are located in the rural southwestern United States. Results indicated that arsenic and uranium concentrations exceeded national drinking water standards in 15.1 % (arsenic) and 12.8 % (uranium) of tested water sources. Unregulated sources in close proximity (i.e., within 6 km) to abandoned uranium mines yielded significantly higher concentrations of arsenic or uranium than more distant sources. The demonstrated regional trends for potential co-exposure to these chemicals have implications for public policy and future research. Specifically, to generate solutions that reduce human exposure to water pollution from unregulated sources in rural areas, the potential for co-exposure to arsenic and uranium requires expanded documentation and examination. Recommendations for prioritizing policy and research decisions related to the documentation of existing health exposures and risk reduction strategies are also provided.

Measurement of uranium concentration by molecular absorption spectrophotometry by means optical fibers

International Nuclear Information System (INIS)

Gauna, Alberto C.; Pascale, Ariel A.

1996-01-01

An on-line method for measuring the concentration of uranium in uranyl nitrate-nitric acid aqueous solutions is described. The method is based on molecular absorption spectrophotometry with transmission of light by means of optical fibers. It is ideally suited for control and processes development applications. (author)

Obtain of uranium concentrates from fertil liquids

International Nuclear Information System (INIS)

Narvaez Castillo, W.A.

1992-01-01

This research tried to encounter the form to remove uranium from the rock in the best way, for that it was used different process like leaching, extraction, concentration and precipitation. To leach the mineral was chosen basic leaching, using a mixture of carbonate-sodium bicarbonate, this method is more adequated for the basic nature of the mineral. In extraction was used specific uranium ionic interchanges, so was chosen a tertiary amine like Alamina 336. The concentration phase is intimately binding with the extraction by ionic interchange, for the capability of resine's extraction to obtain concentrated liquids. When the liquids were obtained with high concentration of uranium in the same time were purified and then were precipitated, for that we employed a precipitant agent like: Sodium hydroxide, Amonium hydroxide, Magnesium hydroxide, Hydrogen peroxide and phosphates. With all concentrates we obtain the YELLOW CAKE

Uranium in open ocean: concentration and isotopic composition

International Nuclear Information System (INIS)

Ku, T.L.; Knauss, K.G.; Mathieu, G.G.

1977-01-01

Uranium concentrations and 234 U/ 238 U activity ratios have been determined in 63 seawater samples (nine vertical profiles) from the Atlantic, and Pacific, and Arctic, and the Antarctic oceans, using the alpha-spectrometric method for their determinations. Correlation between uranium and salinity is well manifested by the data from the Arctic and the Antarctic oceans, but such a relation cannot be clearly defined with the +-(1 to 2)% precision of uranium measurements for the Atlantic and Pacific data. At the 95% confidence level: (1) the uranium/salinity ratio is (9.34 + - 0.56) x 10 -8 g/g for the seawater analyzed with salinity ranging from 30.3 to 36.2 per thousand; the uranium concentration of seawater of 35 per thousand salinity is 3.3 5 + - 0.2 μ g l -1 ; (2) the 234 U/ 238 U activity ratio is 1.14 +- 0.03. Uranium isotopes in interstitial waters of the Pacific surface sediments analyzed do not show large concentration differences across the sediment-water interface as suggested by previous measurements. Current estimations of the average world river uranium concentration (0.3 to 0.6 μ g l -1 ) and 234 U/ 238 U ratio (1.2 to 1.3) and of the diffusional 234 U influx from sediments 0.3 dpm cm -2 10 -3 yr -1 ) are essentially consistent with a model which depicts a steady state distribution of uranium in the ocean. However, the 0.3 to 0.6 μ g l -1 value for river uranium may be an upper limit estimate. (author)

Restoration of uranium solution mining deposits

International Nuclear Information System (INIS)

Devries, F.W.; Lawes, B.C.

1982-01-01

A process is provided for restoring an ore deposit after uranium solution mining using ammonium carbonate leaching solutions has ceased. The process involves flushing the deposit with an aqueous solution of a potassium salt during which potassium ions exchange with ammonium ions remaining in the deposit. The ammonium containing flushing solution is withdrawn from the deposit for disposal

Restoration of uranium solution mining deposits

Energy Technology Data Exchange (ETDEWEB)

Devries, F.W.; Lawes, B.C.

1982-01-19

A process is provided for restoring an ore deposit after uranium solution mining using ammonium carbonate leaching solutions has ceased. The process involves flushing the deposit with an aqueous solution of a potassium salt during which potassium ions exchange with ammonium ions remaining in the deposit. The ammonium containing flushing solution is withdrawn from the deposit for disposal.

Innovative developments in uranium separation and concentration technology abroad

International Nuclear Information System (INIS)

Liang Jinlong; Zhou Mingsheng; Fang Wei; Sun Yuxiang

2014-01-01

Significance of deeply study the innovative developments in Uranium separation and concentration technology abroad was discussed. Development history and innovativeness of eight species of key equipments for separation and concentration were summarized for the first time. Principle and application of seven Uranium separation and concentration technology were analyzed systematically. It is expounded in the paper that high parameter, intelligent and low carbon were three development trends of Uranium separation and concentration technology. (authors)

Removal of Uranium by Exchanger Resins from Soil Washing Solution

Energy Technology Data Exchange (ETDEWEB)

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

2015-05-15

Uranyl ions in the acidic waste solution were sorbed on AM-resin resin with a high sorption efficiency, and desorbed from the resin by a batch-type washing with a 60 .deg. C heated 0.5 M Na{sub 2}CO{sub 3} solution. However, the uranium dissolved in the sulfuric acid solution was not sorbed onto the strong anion exchanger resins. Our group has developed a decontamination process with washing and electrokinetic methods for uranium-contaminated (U-contaminated) soil. However, this process generates a large amount of waste solution containing various metal ions. If the uranium selectively removed from the waste solution, a very small amount of the 2nd waste would be generated. Thus, selective sorption of uranium by ion exchange resins was examined in this study.

Uranium recovery from phosphonitric solutions

International Nuclear Information System (INIS)

Bunus, F.T.; Miu, I.

1997-01-01

A new technology for uranium and rare earth recovery applied in a semi-industrial plant processing 5 m 3 /h phosphoric acid has been extended to phosphonitric solution, resulting in the process of nitric acid attack of phosphate rock for complex fertilizer production. In this process uranium and rare earths are obtained at larger quantities due to the complete dissolution of elements involved. The method is based on a one cycle extraction-stripping process using as extractants: di(2-ethylhexyl) phosphate (DEPA) in mixture either with tri-n-butylphosphate (TBP) or tri-n-octylphosphine oxide (TOPO) in view of obtaining a synergic effect for U (VI). A mixer-settler extractor in four steps was used. Two stripping steps are involved for the elements mentioned. Before uranium stripping a scrubbing with urea was introduced to eliminate nitric acid extracted. Uranium was obtained as green cake (hydrated uranium tetrafluoride) which can be easily transformed in hexfluoride or converted to a diuranate. At the same time the radium is also eliminated leading to a non-radioactive fertilizer product. (author),. 8 refs, 4 figs

Activity concentration of uranium in groundwater from uranium mineralized areas and its neighborhood

International Nuclear Information System (INIS)

Arabi, S.A.; Funtua, I.I.; Dewu, B.B.M.; Alagbe, S.A.; Garba, M.L.; Kwaya, M.Y.; Baloga, A.D.

2013-01-01

Uranium mineralization in parts of northeastern Nigeria necessitated its exploration during early eighties by the Nigeria Uranium Mining Company (NUMCO) which was later abandoned. During their course of decay, uranium isotopes pass through radioactive decay stage and eventually into stable isotope of lead. The course of concern for soluble uranium in groundwater especially from the mineralized areas include ionizing radiation, chemical toxicity and reproductive defects for which ingested uranium has been implicated to have caused. This study is aimed at assessing the levels of concentration of uranium in groundwater to ascertain its compliance with the World Health Organization's (WHO) and the United State Environmental Protection Agency's (EPA) guideline for uranium in drinking water. Thirty five groundwater samples were collected using EPA's groundwater sampling protocol and analyzed at the Department of Geology, University of Cape Town using an Inductively Coupled Plasma Mass Spectrometric (ICP-MS) technique. Significant finding of this work was that there is radiological contamination of groundwater in the area. There is also an indication that the extent of radiological contamination is not much within the mineralized zones, therefore, there is likelihood that groundwater has acted as a medium of transporting and enhancing uranium in groundwater in an environment away from that of origin. About 5.7 % of the samples studied had uranium concentration above WHO and EPA's maximum contaminant level of 30 μg/L which is a major concern for inhabitants of the area. It was also apparent that radiological contamination at the southwestern part of the study area extends into the adjacent sheet (sheet 152). Uranium concentration above set standards in those areas might have originated from rocks around established mineralized zones but was transported to those contaminated areas by groundwater that leaches across the host rock and subsequently mobilizing soluble uranium

EFFECT OF CURRENT, TIME, FEED AND CATHODE TYPE ON ELECTROPLATING PROCESS OF URANIUM SOLUTION

Directory of Open Access Journals (Sweden)

Sigit Sigit

2017-02-01

Full Text Available ABSTRACT   EFFECT OF CURRENT, TIME, FEED AND CATHODE TYPE ON ELECTROPLATING PROCESS OF URANIUM SOLUTION. Electroplating process of uranyl nitrate and effluent process has been carried out in order to collect uranium contained therein using electrode Pt / Pt and Pt / SS at various currents and times. Material used for electrode were Pt (platinum and SS (Stainlees Steel. Feed solution of 250 mL was entered into a beaker glass equipped with Pt anode - Pt cathode or Pt anode - SS cathode, then fogged direct current from DC power supply with specific current and time so that precipitation of uranium sticking to the cathode. After the processes completed, the cathode was removed and weighed to determine weight of precipitates, while the solution was analyzed to determine the uranium concentration decreasing after and before electroplating process. The experiments showed that a relatively good time to acquire uranium deposits at the cathode was 1 hour by current 7 ampere, uranyl nitrate as feed, and Pt (platinum as cathode. In these conditions, uranium deposits attached to the cathode amounted to 74.96% of the original weight of uranium oxide in the feed or 206.5 mg weight. The use of Pt cathode for  uranyl nitrate, SS and Pt cathode for effluent process feed gave uranium specific weight at the cathode of 12.99 mg/cm2, 2.4 mg/cm2 and 5.37 mg/cm2 respectively for current 7 ampere and electroplating time 1 hour. Keywords: Electroplating, uranyl nitrate, effluent process, Pt/Pt electrode, Pt/SS electrode

Uranium removal from organic solutions of PUREX process

International Nuclear Information System (INIS)

Dell'Occhio, L.A.; Dupetit, G.A.; Pascale, A.A.; Vicens, H.E.

1987-01-01

During the uranium extraction process with tributyl phosphate (TBP) in nitric medium, a bi solvated, non hydrated complex is formed, of formula UO2(NO3)2TBP, which is soluble in the diluent, a paraffin hydrocarbon. As it is known that some uranium salts, for instance the nitrate, when dissolved in organic solvents, like isopropanol, can be discharged as complex molecules at the cathode of an electrodeposition cell, it was decided to apply this technique to uranium loaded TBP solutions. From preliminary experiments resulted a practical possibility for the analytical control through the alpha measurement of electro deposits. This technique could be applied as well to the treatment of depleted organic streams carrying undesirable alpha activity, because the so treated solutions become deprived of uranium. This work presents the curves obtained working at constant voltage with uranium-loaded TBP solutions, the determination of the optimal operation voltage in these conditions, the electrodeposition yield for electro polished copper and stainless steel cathodes and the tests of reproducibility of deposits. A summary of the results obtained operating the high voltage supply at constant power is also presented. (Author)

Deactivation and treatment of mine wastewaters and of aqueous solutions discharged in uranium ore treatment and processing

International Nuclear Information System (INIS)

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

1974-01-01

A description is presented of decontamination and purification of mine wastewaters and water solutions discharged from uranium ore treatment and processing and of the simultaneous removal and concentration of uranium-radium daughters, mainly of 226 Ra and 210 Pb. These elements are incorporated in the mycelium of microorganisms, such as those of the Fungi imperfecti class or are sorbed on the mycelium surface. The mycelia are then mechanically separated from the decontaminated solution, e.g., by filtration, centrifugation or sedimentation. The mycelium may be cultivated in the purified solutions to which nutrients are added, such as carbon, nitrogen and phosphorus in concentrations necessary for the growth of the microorganisms used. The mycelium may be added to the purified solution either in the native or in the dried state. (B.S.)

Root uptake of uranium by a higher plant model (Phaseolus vulgaris) bioavailability from soil solution

International Nuclear Information System (INIS)

Laroche, L.; Henner, P.; Camilleri, V.; Garnier-Laplace, J.

2004-01-01

Uranium behaviour in soils is controlled by actions and interactions between physicochemical and biological processes that also determine its bioavailability. In soil solution, uranium(+VI) aqueous speciation undergoes tremendous changes mainly depending on pH, carbonates, phosphates and organic matter. In a first approach to identify bioavailable species of U to plants, cultures were performed using hydroponics, to allow an easy control of the composition of the exposure media. The latter, here an artificial soil solution, was designed to control the uranium species in solution. The geochemical speciation code JCHESS using a database compiled from the OECD/NEA thermochemical database project and verified was used to perform the solution speciation calculations. On this theoretical basis, three domains were defined for short-duration well-defined laboratory experiments in simplified conditions: pH 4.9, 5.8 and 7 where predicted dominant species are uranyl ions, hydroxyl complexes and carbonates respectively. For these domains, biokinetics and characterization of transmembrane transport according to a classical Michaelis Menten approach were investigated. The Free Ion Model (or its derived Biotic Ligand Model) was tested to determine if U uptake is governed by the free uranyl species or if other metal complexes can be assimilated. The effect of different variables on root assimilation efficiency and phyto-toxicity was explored: presence of ligands such as phosphates or carbonates and competitive ions such as Ca 2+ at the 3 pH. According to previous experiments, uranium was principally located in roots whatever the pH and no difference in uranium uptake was evidenced between the main growth stages of the plant. Within the 3 studied chemical domains, results from short-term kinetics evidenced a linear correlation between total uranium concentration in bean roots and that in exposure media, suggesting that total uranium in soil solution could be a good predictor for

Root uptake of uranium by a higher plant model (Phaseolus vulgaris) bioavailability from soil solution

Energy Technology Data Exchange (ETDEWEB)

Laroche, L.; Henner, P.; Camilleri, V.; Garnier-Laplace, J. [CEA Cadarache (DEI/SECRE/LRE), Laboratory of Radioecology and Ecotoxicology, Institute for Radioprotection and Nuclear Safety, 13 - Saint-Paul-lez-Durance (France)

2004-07-01

Uranium behaviour in soils is controlled by actions and interactions between physicochemical and biological processes that also determine its bioavailability. In soil solution, uranium(+VI) aqueous speciation undergoes tremendous changes mainly depending on pH, carbonates, phosphates and organic matter. In a first approach to identify bioavailable species of U to plants, cultures were performed using hydroponics, to allow an easy control of the composition of the exposure media. The latter, here an artificial soil solution, was designed to control the uranium species in solution. The geochemical speciation code JCHESS using a database compiled from the OECD/NEA thermochemical database project and verified was used to perform the solution speciation calculations. On this theoretical basis, three domains were defined for short-duration well-defined laboratory experiments in simplified conditions: pH 4.9, 5.8 and 7 where predicted dominant species are uranyl ions, hydroxyl complexes and carbonates respectively. For these domains, biokinetics and characterization of transmembrane transport according to a classical Michaelis Menten approach were investigated. The Free Ion Model (or its derived Biotic Ligand Model) was tested to determine if U uptake is governed by the free uranyl species or if other metal complexes can be assimilated. The effect of different variables on root assimilation efficiency and phyto-toxicity was explored: presence of ligands such as phosphates or carbonates and competitive ions such as Ca{sup 2+} at the 3 pH. According to previous experiments, uranium was principally located in roots whatever the pH and no difference in uranium uptake was evidenced between the main growth stages of the plant. Within the 3 studied chemical domains, results from short-term kinetics evidenced a linear correlation between total uranium concentration in bean roots and that in exposure media, suggesting that total uranium in soil solution could be a good predictor

Contribution to the study of uranium migration and some trace elements in solution from Pocos de Caldas uranium mining

International Nuclear Information System (INIS)

Zenaro, R.

1989-01-01

It was studied the chemical composition of ground water from four boreholes as a contribution to the hydrogeochemical studies in the Pocos de Caldas uranium mining. Methods for water analyses were selected and optimized in order to determine the main anions, specially the ones which form stable complexes with uranium ions. Fluoride and chloride were determined by potentiometry; phosphate, nitrate and silicate by spectrophotometry. Cations were determined by atomic absorption spectrophotometry flame emission and argon plasma emission excited by continuous current arch (DCP). Uranium was determined by fluorimetry with a concentration range from 3 to 7 ppb and its distribution calculated among the different species into solution through the measures of pH, Eh, anion amounts and stability of their respective complexes. (author) [pt

Uranium concentrate analysis by X-ray fluorescence spectroscopy

International Nuclear Information System (INIS)

Diaz-Guerra, J.P.; Bayon, A.; Roca, R.

1978-01-01

The determination of As, Ca, Fe, Mo, P, S, Si. Th, V and U in uranium concentrates by X-ray fluorescence spectroscopy has been studied. As and U are determined in nitric solutions and for the rest of elements analysis is performed by a bead fusion technique using Li 2 B 4 O 7 and Li 2 CO 3 as fluxes. Although the uranium matrix minimizes the absorption and enhancement effects, because of the content variations of this element it is advisable to operate at a constant level of U 3 O 8 . Despite the high matrix absorption and the large dilution of the samples, sensitivity and speed are found to be satisfactory as the result of the use of a high sensitivity automatic spectrometer. The spectral interferences of Mo on S and P, and of Pb on As have been particularly considered. (author) [es

Predictive geochemical modeling of uranium and other contaminants in laboratory columns in relatively oxidizing, carbonate-rich solutions

International Nuclear Information System (INIS)

Longmire, P.; Turney, W.R.; Mason, C.F.V.

1994-01-01

Carbonate heap leaching of uranium-contaminated soils and sediments represents a viable, cost-effective remediation technology. Column experiments have been conducted using 0.1, 0.25, and 0.5 M Na 2 CO 3 /NaHCO 3 solutions for leaching uranium from soils located adjacent to an incinerator at the Fernald Environmental Management Project (FEMP) site. Results from column experiments and geochemical modeling are used to quantitatively evaluate the effectiveness of heap leaching. Leach efficiencies of up to 72 wt.% of total uranium in CaO-agglomerated soil result from dissolution of uranium (U(VI)-dominated) minerals, formation of the soluble complex UO 2 (CO 3 ) 3 4- , and uranium desorption from clay minerals, ferric hydroxides, and humic acids. Parameters that control the extent of uranium extraction include pH, Eh, temperature, carbonate concentration, lixiviant-flow rate, pore-solution chemistry, solid phases, and soil texture

Extraction equilibrium of uranium (VI) from phosphoric solution with HDEHP and TOPO in cyclohexane

International Nuclear Information System (INIS)

You Jianzhang; Zhou Zuming; Qin Qizong

1988-01-01

The extraction equilibrium of uranium(VI) from phosphoric acid solution with HDEHP and TOPO in cyclohexane has been investigated to examine the effects of extractant concentration, hydrogen ion concentration and temperature on the extraction of uranium(VI). Experimental results suggest that the composition of synergistic complex species is UO 2 (HA 2 ) 2 ·TOPO and the extraction equilibrium constant β 21 is 10 9.52 at 30 deg C. In addition, the thermodynamic functions of the extraction reaction (ΔG,ΔH,ΔS) and the infra-red spectra of synergistic complexes have also been determined

Uranium refining by solvent extraction

International Nuclear Information System (INIS)

Kraikaew, J.; Srinuttrakul, W.

2014-01-01

The solvent extraction process to produce higher purity uranium from yellowcake was studied in laboratory scale. Yellowcake, which the uranium purity is around 70% and the main impurity is thorium, was obtained from monazite processing pilot plant of Rare Earth Research and Development Center in Thailand. For uranium re-extraction process, the extractant chosen was Tributylphosphate (TBP) in kerosene. It was found that the optimum concentration of TBP was 10% in kerosene and the optimum nitric acid concentration in uranyl nitrate feed solution was 4 N. An increase in concentrations of uranium and thorium in feed solution resulted in a decrease in the distribution of both components in the extractant. However, the distribution of uranium into the extractant was found to be more than that of thorium. The equilibration study of the extraction system, UO_2(NO_3)/4N HNO_3 – 10%TBP/Kerosene, was also investigated. Two extraction stages were calculated graphically from 100,000 ppm uranium concentration in feed solution input with 90% extraction efficiency and the flow ratio of aqueous phase to organic phase was adjusted to 1.0. For thorium impurity scrubbing process, 10% TBP in kerosene was loaded with uranium and minor thorium from uranyl nitrate solution prepared from yellowcake and was scrubbed with different low concentration nitric acid. The results showed that at nitric acid normality was lower than 1 N, uranium distributed well to aqueous phase. As conclusion, optimum nitric acid concentration for scrubbing process should not less than 1 N and diluted nitric acid or de-ionized water should be applied to strip uranium from organic phase in the final refining process. (author)

Removal of uranium from ammonium nitrate solution by nanofiltration

Energy Technology Data Exchange (ETDEWEB)

Wang, Runci; Yuan, Zhongwei; Yan, Taihong; Zheng, Weifang [China Institute of Atomic Energy, Beijing (China). Dept. of Radiochemistry

2017-07-01

Two types of nanofiltration membranes were tested to remove uranium dissolved in ammonium nitrate solution, and the influence of operating parameters as transmembrane pressure, tangential velocity and feed temperature was investigated. Experimental results showed NF270 membrane can reject more than 96% uranium and allow most (90% min) ammonium nitrate solution passed by, and with a permeate flux of 60 L/(m{sup 2}.h). Nanofiltration seems to be a promising technology for the removal of uranium and recovery of ammonium nitrate simultaneously.

Analysis of uranium concentrates by atomic-absorption spectrometry

International Nuclear Information System (INIS)

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

1977-01-01

The determination of As, Ca, Fe, Mo and V in uranium concentrates, removing the bulk of the uranium matrix by extracting with tributyl phosphate in hexane has been tried. No interferences were found due to uranium, sodium, aluminium, sulfates and phosphates. Only for calcium a depressive effect of aluminium and uranium has been found and it is overcome by addition of lanthanum. Air-acetylene flame for Fe, Ca and As, and nitrous oxide-acetylene flame for Mo and V have been used. The considered concentration range has been 0.15 - 3% for Ca and Fe, 0.1 -2% for As and 0.1 - 1% for Mo and V. (author) [es

Uranium uptake and accumulation in plants from soil contaminated with uranium in different concentrations

International Nuclear Information System (INIS)

Zhao Luxue; Tang Yongjin; Luo Xuegang

2014-01-01

The plants of Medicago sativa L., Hibiscus esulentus L, Waterspinach, Amaranthus retroflexus and Abutilon theophrasti Medic were employed as the indicator to investigate the uranium uptake and accumulation from soils contaminated with uranium (UO_2 (CH_3COO)_2 · 2H_2O) of 25 mg · kg"-"l, 75 mg · kg"-"1, 125 mg · kg"-"l, 175 mg · kg"-"l respectively, in a pot experiment. The result shows that, U concentration in the aerial part and underground part of the whole plant increased with the rise of uranium concentration in the soils. In the contaminated soils with 25∼125 mg · kg"-"l concentrations of uranium, U content of Medicago sativa L is the highset (6.78 mg · kg"-"l, 61.53 mg · kg"-"l, 74.06 mg · kg"-"l separately). While in the 175 mg · kg"-"l concentration of uranium contaminated soils, U content of Hibiscus esulentus L is the highest (86.72 mg · kg"-"1), which is mainly because of U concentration in its roots have higher level of uranium (388.16 mg · kg"-"l). Comprehensive analysis shows that Medicago sativa L. is a good plant for phytoextraction and Hibiscus esulentus L is a good immobilizing plant for phytoremediation. The results can provide some theoretical basis and technical support for remedying U-contaminated soils in different areas of our country. (authors)

A method of uranium isotopes concentration analysis

International Nuclear Information System (INIS)

Lin Yuangen; Jiang Meng; Wu Changli; Duan Zhanyuan; Guo Chunying

2010-01-01

A basic method of uranium isotopes concentration is described in this paper. The iteration method is used to calculate the relative efficiency curve, by analyzing the characteristic γ energy spectrum of 235 U, 232 U and the daughter nuclide of 238 U, then the relative activity can be calculated, at last the uranium isotopes concentration can be worked out, and the result is validated by the experimentation. (authors)

Uranium solution mining: comparison of New Mexico with South Texas

International Nuclear Information System (INIS)

Conine, W.D.

1980-01-01

In-situ uranium-leaching or solution-mining operations are currently underway in both south Texas and Wyoming. Mobil Oil Corporation is in the process of applying solution-mining technology, such as that developed at the O'Hern facility in south Texas, to uranium orebodies located near Crownpoint, New Mexico. The O'Hern facility uses an alkaline-leach process to bring the uranium to the surface, where it is removed from solution using ion-exchange resin and chemical precipitation. Line-drive and five-spot well field patterns are used to inject and recover the leach solutions. Although details of ore occurrence in New Mexico differ from those in south Texas, laboratory, engineering-design, and field-hydrology tests indicate that solution mining of uranium should be feasible in New Mexico. To determine the commercial feasibility, Mobil is proceeding with the construction of pilot-plant facilities for a 75-gallon-perminute (gpm) test at an orebody near Crownpoint. The pilot test will use five-spot patterns at various spacings for production of uranium-bearing leachate. Initial surface processing will be the same as that used in south Texas

Uranium isotopic composition and uranium concentration in special reference material SRM A (uranium in KCl/LiCl salt matrix)

International Nuclear Information System (INIS)

Graczyk, D.G.; Essling, A.M.; Sabau, C.S.; Smith, F.P.; Bowers, D.L.; Ackerman, J.P.

1997-07-01

To help assure that analysis data of known quality will be produced in support of demonstration programs at the Fuel Conditioning Facility at Argonne National Laboratory-West (Idaho Falls, ID), a special reference material has been prepared and characterized. Designated SRM A, the material consists of individual units of LiCl/KCl eutectic salt containing a nominal concentration of 2.5 wt. % enriched uranium. Analyses were performed at Argonne National Laboratory-East (Argonne, IL) to determine the uniformity of the material and to establish reference values for the uranium concentration and uranium isotopic composition. Ten units from a batch of approximately 190 units were analyzed by the mass spectrometric isotope dilution technique to determine their uranium concentration. These measurements provided a mean value of 2.5058 ± 0.0052 wt. % U, where the uncertainty includes estimated limits to both random and systematic errors that might have affected the measurements. Evidence was found of a small, apparently random, non-uniformity in uranium content of the individual SRM A units, which exhibits a standard deviation of 0.078% of the mean uranium concentration. Isotopic analysis of the uranium from three units, by means of thermal ionization mass spectrometry with a special, internal-standard procedure, indicated that the uranium isotopy is uniform among the pellets with a composition corresponding to 0.1115 ± 0.0006 wt. % 234 U, 19.8336 ± 0.0059 wt. % 235 U, 0.1337 ± 0.0006 wt. % 236 U, and 79.9171 ± 0.0057 wt. % 238 U

Process for extracting uranium from phosphoric acid solutions

International Nuclear Information System (INIS)

1977-01-01

The description is given of a method for extracting uranium from phosphoric acid solutions whereby the previously oxided acid is treated with an organic solvent constituted by a mixture of dialkylphosphoric acid and trialkylphosphine oxide in solution in a non-reactive inert solvent so as to obtain de-uraniated phosphoric acid and an organic extract constituted by the solvent containing most of the uranium. The uranium is then separated from the extract as uranyl ammonium tricarbonate by reaction with ammonia and ammonium carbonate and the extract de-uraniated at the extraction stage is recycled. The extract is treated in a re-extraction apparatus comprising not less than two stages. The extract to be treated is injected at the top of the first stage. At the bottom of the first stage, ammonia is introduced counter current as gas or as an aqueous solution whilst controlling the pH of the first stage so as to keep it to 8.0 or 8.5 and at the bottom of the last stage an ammonium carbonate aqueous solution is injected in a quantity representing 50 to 80% of the stoichiometric quantity required to neutralize the dialkylphosphoric acid contained in the solvent and transform the uranium into uranyl ammonium tricarbonate [fr

REMOVAL AND CONCENTRATION OF URANIUM FROM WASTE MINE

Directory of Open Access Journals (Sweden)

Elizângela Augusta Santos

2011-01-01

Full Text Available The use of leaching agents, such as sodium citrate and ammonium carbonate, were assessed for the extraction of uranium from one mining residue containing 0.25% U. Concentration techniques such as precipitation and ion exchange were employed to recover the uranium from the leaching liquor. Leaching results showed maximum uranium extraction of about 40% for both reagents. The use 10 mol L-1 NaOH to precipitate the uranium from the leach liquor leads to a recovery of 62%; what was considered not satisfactory. In view of this, resins were used to concentrate the uranium from the liquor and the metal loading obtained at pH 3.9 was higher for the resin DOWEX RPU, whose maximum loading maximum capacity was 148.3 mg g-1, compared to 126.9 mg g-1 presented by the resin IRA 910 U.

Rirang uranium ore processing: continuous solvent extraction of uranium from Rirang ore acid digestion solution

International Nuclear Information System (INIS)

Riza, F.; Nuri, H. L.; Waluya, S.; Subijanto, A.; Sarono, B.

1998-01-01

Separation of uranium from Rirang ore acid digestion solution by means of continuous solvent extraction using mixer-settlers has been studied and a mixture of 0.3 M D2EHPA and 0.075 M TOPO extracting agent and kerosene diluent is employed to recover and separate uranium from Th, RE, phosphate containing solution. The experiments have been conducted batch-wise and several parameters have been studied including the aqueous to organic phase ratio, A/O, the extraction and the stripping times, and the operation temperature. The optimum conditions for extraction have been found to be A/O = 2 ratio, five minute extraction time per stage at room temperature. The uranium recovery of 99.07% has been achieved at those conditions whilst U can be stripped from the organic phase by 85% H 3 PO 4 solution with an O/A = 1 for 5 minutes stripping time per stage, and in a there stage operation at room temperature yielding a 100% uranium recovery from the stripping process

Preferential adsorption of uranium ions in aqueous solutions by polymers

International Nuclear Information System (INIS)

Sakuragi, Masako; Ichimura, Kunihiro; Fujishige, Shoei; Kato, Masao

1981-01-01

Amidoxime fiber and triazine fiber were prepared by chemical modification of commercially available polyacrylonitril fiber. It was found that the Amidoxime fiber is efficient to adsorb uranium ions in the artificial sea water. The efficiency of the preferential adsorption decreases by treatment the material with an acid-or an alkaline-solution. The triazine fiber adsorbs uranium ions only in aqueous solutions of such uranyl acetate, in the absence of other ions. In the artificial sea water, it adsorbs other ions instead of uranium. The preferential adsorption of uranium ions was further investigated with a series of polystyrenesulfonamides. Among the polystyrene derivatives, those having carboxyl groups, derived from imino diacetic acid (PSt-Imi), β-alanine (PSt-Ala), glycine (PSt-Gly), and sarcosine (PSt-Sar) were qualified for further discussion. However, it was found that the amount of adsorption of uranium ions by PSt-Imi decreases with increasing the volume of the artificial sea water and/or the duration of the treatment. Taking into account the facts, the preferential adsorption of uranium ions by PSt-Imi in aqueous solution was discussed in detail. (author)

Experimental critical parameters of enriched uranium solution in annular tank geometries

International Nuclear Information System (INIS)

Rothe, R.E.

1996-04-01

A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant's Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this concentration varied a little over the duration of the studies. The uranium was enriched to about 93% [sup 235]U. All tanks were typical of sizes commonly found in nuclear production plants. They were about 2 m tall and ranged in diameter from 0.6 m to 1.5 m. Annular thicknesses and conditions of neutron reflection, moderation, and absorption were such that criticality would be achieved with these dimensions. Only 13 of the entire set of 74 experiments proved to be subcritical when tanks were completely filled with solution. Single tanks of several radial thicknesses were studied as well as small line arrays (1 x 2 and 1 x 3) of annular tanks. Many systems were reflected on four sides and the bottom by concrete, but none were reflected from above. Many experiments also contained materials within and outside the annular regions that contained strong neutron absorbers. One program had such a thick external moderator/absorber combination that no reflector was used at all

Experimental critical parameters of enriched uranium solution in annular tank geometries

Energy Technology Data Exchange (ETDEWEB)

Rothe, R.E.

1996-04-01

A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant`s Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this concentration varied a little over the duration of the studies. The uranium was enriched to about 93% [sup 235]U. All tanks were typical of sizes commonly found in nuclear production plants. They were about 2 m tall and ranged in diameter from 0.6 m to 1.5 m. Annular thicknesses and conditions of neutron reflection, moderation, and absorption were such that criticality would be achieved with these dimensions. Only 13 of the entire set of 74 experiments proved to be subcritical when tanks were completely filled with solution. Single tanks of several radial thicknesses were studied as well as small line arrays (1 x 2 and 1 x 3) of annular tanks. Many systems were reflected on four sides and the bottom by concrete, but none were reflected from above. Many experiments also contained materials within and outside the annular regions that contained strong neutron absorbers. One program had such a thick external moderator/absorber combination that no reflector was used at all.

Optimization of Davies and Gray/NBL method used for determination of total uranium concentration in the safeguards destructive analysis

International Nuclear Information System (INIS)

Silva, Jose Wanderley S. da; Viana, Aline Gonzalez; Barros, Pedro Dionisio de; Cristiano, Barbara Fernandes G.

2013-01-01

One important activity conducted by the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC is to verify inventories of the nuclear facilities by nondestructive analysis and destructive analysis. For destructive analysis, the Safeguards Laboratory of Brazilian Nuclear Energy Commission - LASAL/CNEN has been applying the 'Davies and Gray/NBL' method in samples taken during inspections at nuclear facilities since 1984 in Brazil and Argentina. This method consists of the determination of total uranium concentration by potentiometric titration of uranium (IV) with a standard solution of potassium dichromate as oxidizing agent. This solution is prepared using a K 2 Cr 2 O 7 SRM 136e standard reference material (99.984 ±0.010) wt% certified by National Institute of Standard and Technology - NIST. The procedure also includes the calibration with primary uranium standards reference material (NBL CRM 112A). In order to reduce the consumption of K 2 Cr 2 O 7 and the other reagent involved in the procedure, without any loss in the performance of the method, a K 2 Cr 2 O 7 solution with half the regular concentration was prepared and used to test the uranium concentration in several aliquots with a content between 30 mg to 40 mg of uranium per gram of solution. After optimizing the parameters and procedure, it was possible to get the same performance as well. As a consequence, decreasing of the cost, the amount of waste and also a reduction in the titration time of each aliquot was achieved. Thus, this work describes all details in this research as well as the results and its evaluation. (author)

A survey of natural uranium concentrations in drinking water supplies in Iran

International Nuclear Information System (INIS)

Alirezazadeh, N.; Garshasbi, N.

2003-01-01

Background: Measurement of background concentration of uranium in drinking water is very important for many reasons, specially, for human health. The uranium concentration in drinking water in many countries is a matter of concern for clinical and radioactive poisoning. Materials and methods: The uranium concentration in drinking water is determined using laser fluorimetric uranium analyzer. For this purpose after sampling, sample handling and sample preserving, sample preparation and treatment for reduction of organic matter, the concentration of uranium is measured. Results: To determine the uranium concentrations in drinking water in Iran, nearly 200 water samples were collected from all sources supplying drinking water in 21 provincial centers in the country. The wells were found to be the main source for drinking water. Uranium in the samples was measured by a laser fluorimetry technique. According to results, the concentration values found in the wells ranged from 1.0 to 10.90 μgL -1 , while nearly 95 percent of the cities had uranium concentrations in the wells at less than 4.70 μgL -1 . Surface waters showed uranium concentrations in the range of 0.75 to 2.58 μgL -1 . The daily intake of uranium from drinking water was estimated to range from 2.04 to 21.80 μgd -1 , with the mean value of 5.44 μgd -1 . Conclusion: Highest uranium mean concentration of 10.9 μgL -1 was found in Ardabil area where more studies should be done in that province in the future

Bioaccumulation of uranium and thorium from the solution containing both elements using various microorganisms

International Nuclear Information System (INIS)

Tsuruta, T.

2006-01-01

The effects of proton, thorium and uranium on the bioaccumulation of thorium and uranium from the solution (pH 3.5) containing uranium and thorium using Streptomyces levoris cells were examined. The amount of thorium accumulated using the cells decreased by the pre-contact between the cells and the solution (pH 3.5) containing no metals, whereas that of uranium was almost unaffected by the treatment. The amount of thorium was almost unaffected by the existence of uranium. On the other hand, the amount of uranium accumulated was strongly affected by the thorium, especially thorium addition after uranium accumulation. The decrease of uranium accumulated by the addition of thorium after the accumulation of uranium was higher than that from the solution containing both elements. Therefore, the contribution of uranium-thorium exchange reaction was higher than that of competition reaction. Accordingly, proton-uranium-thorium exchange reaction was occurred in the accumulation of thorium from the solution containing thorium and uranium. The gram-positive bacteria, such as Micrococcus luteus, Arthrobacter nicotianae, Bacillus subtilis and B. megaterium, has a much higher separation factor as thorium/uranium than that of actinomycetes. These gram-positive bacterial strains can be used for the accumulation of thorium from the solution containing uranium and thorium

EPR study of the production of OH radicals in aqueous solutions of uranium irradiated by ultraviolet light

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MARKO DAKOVIĆ

2009-06-01

Full Text Available The aim of the study was to establish whether hydroxyl radicals (•OH were produced in UV-irradiated aqueous solutions of uranyl salts. The production of •OH was studied in uranyl acetate and nitrate solutions by an EPR spin trap method over a wide pH range, with variation of the uranium concentrations. The production of •OH in uranyl solutions irradiated with UV was unequivocally demonstrated for the first time using the EPR spin-trapping method. The production of •OH can be connected to speciation of uranium species in aqueous solutions, showing a complex dependence on the solution pH. When compared with the results of radiative de-excitation of excited uranyl (*UO22+ by the quenching of its fluorescence, the present results indicate that the generation of hydroxyl radicals plays a major role in the fluorescence decay of *UO22+. The role of the presence of carbonates and counter ions pertinent to environmental conditions in biological systems on the production of hydroxyl radicals was also assessed in an attempt to reveal the mechanism of *UO22+ de-excitation. Various mechanisms, including •OH production, are inferred but the main point is that the generation of •OH in uranium containing solutions must be considered when assessing uranium toxicity.

Restoration of uranium solution mining deposits

International Nuclear Information System (INIS)

DeVries, F.W.; Lawes, B.C.

1981-01-01

Ammonium carbonates are commonly used as the lixiviant for in-situ leaching of uranium ores. However this leads to the deposition of ammonium ions in the uranium ore formation and the problem of ammonia contamination of ground water which may find its way into the drinking water supply. The ammonia contamination of the ore deposit may be reduced by injecting an aqueous solution of a potassium salt (carbonate, bicarbonate, halide, sulfate, bisulfate, persulfate, or monopersulfate) into the deposit after mining has ceased

Potentiality of uranium biosorption from nitric acid solutions using shrimp shells

International Nuclear Information System (INIS)

Ahmed, S.H.; El Sheikh, E.M.; Morsy, A.M.A.

2014-01-01

Biosorption has gained important credibility during recent years because of its good performance and low cost. This work is concerned with studying the potentiality of the chitin component of the shrimp shells for uranium biosorption from nitric acid liquid solutions. The structural characteristics of the working chitin have been determined via Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was examined using Scanning Electron Microscopy (SEM). The adsorption capacity of biomass was investigated experimentally. The influence of contact time, pH, metal ion concentration, solution volume to mass ratio and temperature were evaluated and the results were fitted using adsorption isotherm models. The kinetic of uranium biosorption was also investigated as well as biosorption thermodynamic. - Graphical abstract: Physicochemical process of biosorption is known to be promising technique due to the ease of operation and comparable low cost of biosorbant application. Chitin flakes extracted from shrimp shells show potentiality in uranium adsorption reached 7.48 mg uranium at the following conditions: 60 min contact time, pH 3.66, 50:1 V/m ration and at room temperature. The theoretical sorption capacity was 25.31 mg g −1 , according to Langmuir isotherm model. The rate of sorption follows pseudo second-order. The nature of biosorption process is spontaneous and exothermic. - Highlights: • This study shows the potentially for shrimp shell beads for uranium adsorption. • The max. biosorption was achieved at pH 3.6, contact time 60 min, S/L ratio 1:50. • Uranium sorption follows Langmuir isotherm with theoretical capacity of 25.31 g/kg. • The nature of sorption process of the sorbents is spontaneous and exothermic. • The rate of sorption follows pseudo second-order

Molybdenum from uranium solutions

International Nuclear Information System (INIS)

Gardner, H.E.

1981-01-01

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

Determination of trace amounts of uranium in a reprocessing plant by solution spectrofluorimetry

International Nuclear Information System (INIS)

Mauchien, P.; Cauchetier, Ph.

1983-01-01

To establish inventory tables accurately and satisfy safeguards requirements - and also to ensure satisfactory operation of a reprocessing plant - it is essential to determine the uranium content of numerous solutions where the uranium is present only in trace quantities. For this purpose a method is proposed which relies on the fluorescence of uranyl solutions exposed to ultra-violet radiation. After a brief theoretical summary, the parameters which influence the measurements most strongly are enumerated: medium, temperature, nature of the matrix, and choice of wavelength of the incident radiation. It is then apparent that the measurement must be performed by internal calibration (using the proportional addition method) and that it is useful to obtain a fluorescence spectrum which enables us to verify the presence of uranium. The applications of this method at the La Hague plant are described, where it has been used since October 1981 by shift teams, notably to check the following points: the attack acid (before receiving the fuel), the foot of the first-cycle column, the carbonated solvent washing solution and the solutions of the effluent treatment unit. It is in fact used throughout the plant, even for checking uranium in PuO 2 oxide. The method makes it possible to avoid organic reagents such as pyridine and, in many cases, cumbersome effluent-generating separations. Determinations are possible - to give one example - by simple dilution in the fission-product concentrates and in plutonium solutions where the Pu/U ratio is as great as 1000/1. In pure solutions the detection limit with the equipment used at present is a few μg per litre in the measuring tank. In general, the accuracy is a few per cent. (author)

Determination of contents of carbonate and hydrogen carbonate in solutions for alkaline leading of uranium ores

International Nuclear Information System (INIS)

Radil, V.

1988-01-01

The new analytical method is based on the determination of the molar ratio carbonate - hydrogen carbonate using the measured concentration of hydrogen ions, the determination of the dissociation constant of carbonic acid for different values of ionic strength. The concentration of hydrogen ions was measured with a Metrohm 632 pH meter with the use of a combined glass electrode. The content of total carbonate carbon was determined coulometrically and the uranium content was determined by extraction with tributyl phosphate and by spectrometry of the complex of uranyl ions with Arsenazo III. Model solutions were used for the experiments which contained a high concentration of sulfate ions, thiosulfate ions, uranium and various proportions of carbonate and hydrogen carbonate. The composition of the individual samples of the extraction solutions are tabulated. The calibration was made of the glass combined electrode at different ionic strength, the values determined of dissociation constants of carbonic acid for different ionic strength. The mathematical procedure is described for the calculation of molar concentrations of carbonate and hudrogen carbonate and the results are presented of the analysis of model solutions. (E.S.). 5 tabs., 1 fig., 5 refs

Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles.

Science.gov (United States)

Fan, Fang-Li; Qin, Zhi; Bai, Jing; Rong, Wei-Dong; Fan, Fu-You; Tian, Wei; Wu, Xiao-Lei; Wang, Yang; Zhao, Liang

2012-04-01

Rapid removal of U(VI) from aqueous solutions was investigated using magnetic Fe(3)O(4)@SiO(2) composite particles as the novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, shaking time and initial U(VI) concentrations on uranium sorption efficiency as well as the desorbing of U(VI). The sorption of uranium on Fe(3)O(4)@SiO(2) composite particles was pH-dependent, and the optimal pH was 6.0. In kinetics studies, the sorption equilibrium can be reached within 180 min, and the experimental data were well fitted by the pseudo-second-order model, and the equilibrium sorption capacities calculated by the model were almost the same as those determined by experiments. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 20-200 mg/L. The maximum uranium sorption capacity onto magnetic Fe(3)O(4)@SiO(2) composite particles was estimated to be about 52 mg/g at 25 °C. The highest values of uranium desorption (98%) was achieved using 0.01 M HCl as the desorbing agent. Fe(3)O(4)@SiO(2) composite particles showed a good selectivity for uranium from aqueous solution with other interfering cation ions. Present study suggested that magnetic Fe(3)O(4)@SiO(2) composite particles can be used as a potential adsorbent for sorption uranium and also provided a simple, fast separation method for removal of heavy metal ion from aqueous solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Airborne uranium, its concentration and toxicity in uranium enrichment facilities

International Nuclear Information System (INIS)

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

1979-02-01

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

The role of solutions and uranium geochemistry in the geological formations of Jabal Abou-Rejmain-Northern Palmyrides

International Nuclear Information System (INIS)

Jubeli, Y.; Aissa, M.; Al-Hilall, M.

1999-09-01

The equivalent concentration of potassium, uranium, thorium and total radioactivity of various geological outcrops, along the major wadis of the southern and northern flanks of Jabal Abou-Rejmain, were determined. The radiometric anomalies found to be closely related to either phosphate beds of Companion age, or to spots of yellow secondary uranium minerals precipitated on very soft gray marly limestone rocks of Maestrichtian age. The present work indicates that phosphat deposition in the northern palmy rides seems to be widely distributed in the northern Patmyrides more than it was known earlier. The occurrences of secondary uranium mineralization coincide with the presence of evaporates, such as gypsum, which indicates that the precipitation occurs out of uranium enriched solution which were subjected to aridity and evaporation. The soft marly limestone rocks contains the highest percentage of clay fraction. This fraction is responsible for razing and absorbing the solutions, which were leached out of the Companion facies leading to precipitation of uranium minerals on the surface, as well as, within the pores of the rocks. However, transportation of these solutions, in the study area, seems not to extent for a long distance. (author

Study on the utilization of a sodium-sulfuric acid solution for the uranium minerals' leaching

International Nuclear Information System (INIS)

Echenique, Patricia; Fruchtenicht, Fernando; Gil, Daniel; Vigo, Daniel; Bouza, Angel; Vert, Gabriela; Becquart, Elena

1988-01-01

Argentine uranium minerals have been leached at bench scale with a different agent trying to reduce sulfuric acid consumption. The leaching agent was a sodium sulfate-sulfuric acid solution and the ore was from Sierra Pintada (San Rafael - Mendoza). The work was performed in stirred vessel at atmospheric pressure. The influence of different variables, pH, temperature, oxidant agent, sodium sulfate concentration and time, in the sulfuric acid consumption and the uranium yield was studied. (Author) [es

HPAT: A nondestructive analysis technique for plutonium and uranium solutions

International Nuclear Information System (INIS)

Aparo, M.; Mattia, B.; Zeppa, P.; Pagliai, V.; Frazzoli, F.V.

1989-03-01

Two experimental approaches for the nondestructive characterization of mixed solutions of plutonium and uranium, developed at BNEA - C.R.E. Casaccia, with the goal of measuring low plutonium concentration (<50 g/l) even in presence of high uranium content, are described in the following. Both methods are referred to as HPAT (Hybrid Passive-Active Technique) since they rely on the measurement of plutonium spontaneous emission in the LX-rays energy region as well as the transmission of KX photons from the fluorescence induced by a radioisotopic source on a suitable target. Experimental campaigns for the characterization of both techniques have been carried out at EUREX Plant Laboratories (C.R.E. Saluggia) and at Plutonium Plant Laboratories (C.R.E. Casaccia). Experimental results and theoretical value of the errors are reported. (author)

Optimization of Davies and Gray/NBL method used for determination of total uranium concentration in the safeguards destructive analysis

Energy Technology Data Exchange (ETDEWEB)

Silva, Jose Wanderley S. da; Viana, Aline Gonzalez; Barros, Pedro Dionisio de; Cristiano, Barbara Fernandes G., E-mail: wanderley@ird.gov.br, E-mail: agonzalez@ird.gov.br, E-mail: pedrodio@ird.gov.br, E-mail: barbara@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2013-07-01

One important activity conducted by the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC is to verify inventories of the nuclear facilities by nondestructive analysis and destructive analysis. For destructive analysis, the Safeguards Laboratory of Brazilian Nuclear Energy Commission - LASAL/CNEN has been applying the 'Davies and Gray/NBL' method in samples taken during inspections at nuclear facilities since 1984 in Brazil and Argentina. This method consists of the determination of total uranium concentration by potentiometric titration of uranium (IV) with a standard solution of potassium dichromate as oxidizing agent. This solution is prepared using a K{sub 2}Cr{sub 2}O{sub 7} SRM 136e standard reference material (99.984 ±0.010) wt% certified by National Institute of Standard and Technology - NIST. The procedure also includes the calibration with primary uranium standards reference material (NBL CRM 112A). In order to reduce the consumption of K{sub 2}Cr{sub 2}O{sub 7} and the other reagent involved in the procedure, without any loss in the performance of the method, a K{sub 2}Cr{sub 2}O{sub 7} solution with half the regular concentration was prepared and used to test the uranium concentration in several aliquots with a content between 30 mg to 40 mg of uranium per gram of solution. After optimizing the parameters and procedure, it was possible to get the same performance as well. As a consequence, decreasing of the cost, the amount of waste and also a reduction in the titration time of each aliquot was achieved. Thus, this work describes all details in this research as well as the results and its evaluation. (author)

Process for recovering uranium using an alkyl pyrophosphoric acid and alkaline stripping solution

International Nuclear Information System (INIS)

Worthington, R.E.; Magdics, A.

1987-01-01

A process is described for stripping uranium for a pregnant organic extractant comprising an alkyl pyrophosphoric acid dissolved in a substantially water-immiscible organic diluent. The organic extractant contains tetravalent uranium and an alcohol or phenol modifier in a quantity sufficient to retain substantially all the unhydrolyzed alkyl pyrophosphoric acid in solution in the diluent during stripping. The process comprises adding an oxidizing agent to the organic extractant and thereby oxidizing the tetravalent uranium to the +6 state in the organic extractant, and contacting the organic extractant containing the uranium in the +6 state with a stripping solution comprising an aqueous solution of an alkali metal or ammonium carbonate or hydroxide thereby stripping uranium from the organic extractant into the stripping solution. The resulting barren organic extractant containing substantially all of the unhydrolyzed alkyl pyrophosphoric acid dissolved in the diluent is separated from the stripping solution containing the stripped uranium, the barren extractant being suitable for recycle

Potentiometric titration of free acid in uranium solutions

International Nuclear Information System (INIS)

Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

1998-02-01

Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors' researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors' researches are appended. (author). 26 refs., 54 figs

Potentiometric titration of free acid in uranium solutions

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

1998-02-01

Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors` researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors` researches are appended. (author). 26 refs., 54 figs.

Preparation of uranium standard solutions for x-ray fluorescence analysis

International Nuclear Information System (INIS)

Wong, C.M.; Cate, J.L.; Pickles, W.L.

1978-03-01

A method has been developed for gravimetrically preparing uranium nitrate standards with an estimated mean error of 0.1% (1 sigma) and a maximum error of 0.2% (1 sigma) for the total uranium weight. Two source materials, depleted uranium dioxide powder and NBS Standard Reference Material 960 uranium metal, were used to prepare stock solutions. The NBS metal proved to be superior because of the small but inherent uncertainty in the stoichiometry of the uranium oxide. These solutions were used to prepare standards in a freeze-dried configuration suitable for x-ray fluorescence analysis. Both gravimetric and freeze-drying techniques are presented. Volumetric preparation was found to be unsatisfactory for 0.1% precision for the sample size of interest. One of the primary considerations in preparing uranium standards for x-ray fluorescence analysis is the development of a technique for dispensing a 50-μl aliquot of a standard solution with a precision of 0.1% and an accuracy of 0.1%. The method developed corrects for variation in aliquoting and for evaporation loss during weighing. Two sets, each containing 50 standards have been produced. One set has been retained by LLL and one set retained by the Savannah River project

Effect of chloride concentration on the solubility of amorphous uranium dioxide at 25deg C under reducing conditions

International Nuclear Information System (INIS)

Aguilar, M.; Casas, I.; Pablo, J. de; Torrero, M.E.

1991-01-01

The dependence of the solubility of a microcrystalline uranium dioxide on the chloride concentration has been studied at 25deg C under reducing conditions. The concentration of uranium in solution has been found to be some orders of magnitude lower than in perchlorate media. Possible changes of both the morphology and the composition of the solid phase have been investigated by means of Energy Dispersive X-ray Analysis (EDX) and X-ray Powder Difraction (XPD). The formation of a secondary solid phase as a reason for the decrease of the solubility has been postulated. (orig.)

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.

Plans and equipment for criticality measurements on plutonium-uranium nitrate solutions

International Nuclear Information System (INIS)

Lloyd, R.C.; Clayton, E.D.; Durst, B.M.

1982-01-01

Data from critical experiments are required on the criticality of plutonium-uranium nitrate solutions to accurately establish criticality control limits for use in processing and handling of breeder type fuels. Since the fuel must be processed both safely and economically, it is necessary that criticality considerations be based on accurate experimental data. Previous experiments have been reported on plutonium-uranium solutions with Pu weight ratios extending up to some 38 wt %. No data have been presented, however, for plutonium-uranium nitrate solutions beyond this Pu weight ratio. The current research emphasis is on the procurement of criticality data for plutonium-uranium mixtures up to 60 wt % Pu that will serve as the basis for handling criticality problems subsequently encountered in the development of technology for the breeder community. Such data also will provide necessary benchmarks for data testing and analysis on integral criticality experiments for verification of the analytical techniques used in support of criticality control. Experiments are currently being performed with plutonium-uranium nitrate solutions in stainless steel cylindrical vessels and an expandable slab tank system. A schematic of the experimental systems is presented

The Influences of Uranium Concentration and Polyvinyl Alcohol on the Quality UO2 Microsphere for Fuel of High Temperature Reactor

International Nuclear Information System (INIS)

Damunir; Sukarsono; Bangun-Wasito; Endang Nawangsih

2000-01-01

The influences of uranium concentration and PVA on the quality of UO 2 microspheres for fuel of high temperature reactor have been investigated. The UO 2 particles were prepared by gel precipitation using internal gelation process. Uranyl nitrate solution containing uranium of 100 g/l was neutralized using NH 4 OH 1 M. The solution was changed into sol by adding 60 g PVA/l solution while stirred and heated up to 80 o C for 20 minutes. In order to find gels in spherical shape, the sol solution was dropped into 5 M NH 4 OH medium. The formed gels were small spheres, was washed, screened and heated up to 120 o C. After that, the gels were calcined at 800 o C for 4 hours, resulting in U 3 O 8 spheres. The U 3 O 8 particles were reduced using H 2 gas in a N 2 media at 800 o C for 4 hours, yielded in UO 2 spheres. Using a similar procedure, the influence of uranium concentration of 150-250 g/l and PVA 40-80 g/l were studied. The qualities of UO 2 particles were obtained by their physical properties, i.e. density, specific surface area, total volume of pores and pore radius using surface area meter and N 2 gas used as absorbent, and the particle size was observed using optical microscope. The result showed that the changing of uranium and PVA concentrations on the internal gelation affected the density, specific surface area, total volume of pores and pore radius of UO 2 particles. (author)

Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

International Nuclear Information System (INIS)

Cemal Oezeroglu; Niluefer Metin

2012-01-01

In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (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

finely divided inorganic absorbers. The general procedure for the preparation of the resulting inorganic-organic composite absorbers enables preparation of suitably grained composite absorbers. The contents of active component may reach up to 90% (W/W) in dry residue. The aim of this study was to verify possibility of extraction of uranium with TiO-PAN and NaTiO-PAN composite absorbers, to compare properties of these two absorbers and to conclude whether they are prospective for uranium collection from surface and/or waste waters. Hydrated titanium oxide (TiO) and sodium titanate (NaTiO) -the active components of the composite materials-were prepared from industrial intermediate from production of titanium white. Standard procedure was used to prepare the TiO-PAN and NaTiO-PAN composite absorbers. In the experiments, distilled and tap water were used to compare the influence of the water hardness. pH of the effluent was also measured during the process. The results showed that practical sorption capacity (10% break-through) from tap water containing 2.3 μg U.mL -1 measured at flow rate of 100 BV.h -1 was ∼ 4.6 mg and ∼1.5 mg of uranium per ml of swollen TiO-PAN and NaTiO-PAN absorber, respectively. The maximum flow rates are 60 BV.h -1 and 60-100 BV.h -1 for TiO-PAN and NaTiO-PAN absorbers, respectively, depending on the concentration of uranium (2.3-230 mg U.L -1 ). Elution of uranium and regeneration of the absorber may be accomplished by 0.1 mol.L -1 or stronger solutions of hydrochloric acid for both the absorbers. Hence, TiO-PAN and NaTiO-PAN composite absorbers were proved to be applicable for extraction of uranium from aqueous solutions. With respect to the measured practical sorption capacity, TiO-PAN composite absorber is more suitable for the uranium collection from surface and/or waste water. (author)

Analytical procedure for the titrimetric determination of uranium in concentrates

International Nuclear Information System (INIS)

Florence, T.M.; Pakalns, P.

1989-01-01

In 1964 Davis and gray published a titrimetric method for uranium which does not require column reductors, electronic instruments or inert atmospheres, and is sufficiently selective to enable uranium to be determined without prior separation. The method involves reduction of uranium (VI) to (IV) by ferrous sulphate in concentrated phosphoric acid medium. The excess ion (II) is then selectively oxidised by nitric acid using molybdenum catalyst. After addition of sulphuric acid and dilution with water, the uranium (IV) is titrated with standard potassium dichromate, using barium diphenylamine sulphonate indicator. This method has been found to be simple, precise and reliable, and applicable to a wide range of uranium-containing materials. The method given here for determining uranium in concentrates is essentially that of Davies and Gray. Its applications, apparatus, reagents, procedures and accuracy and precision are discussed. 10 refs

Concentration and purification of plutonium solutions by means of ion-exchange columns

Energy Technology Data Exchange (ETDEWEB)

Durham, R W; Aikin, A M

1953-02-15

Equilibrium experiments using Dowex 50 ion-exchange resin and nitric acid solutions of Pu{sup 3+}, UO{sub 2}{sup 2+}, Fe{sup 2+} cations have yielded values for the absorption affinities for these ions. Trivalent plutonium was found to be far more strongly absorbed than UO{sub 2}{sup 2+} and Fe{sup 2+}. Column studies have shown that uranium can be completely separated from plutonium even when the initial concentration of uranium is very much greater than that of the plutonium. A plutonium concentration increase of about fifty-fold can be obtained from solutions about 10{sup -3} M in plutonium and 1.0M in nitric acid. The equation K{sub Pu}{sup 3+} = X{sub R} (1-X{sub S}){sup 3} C{sub S}{sup 2}/X{sub S} (1-X{sub R}){sup 3} C{sub R}{sup 2} for estimating the maximum amount of plutonium taken up by a column of resin of unit volume from a solution of total equivalent concentration, C{sub S} , has been shown to hold for values of C{sub S} up to 3 equivalents per litre. X{sub R}, the equivalent fraction of plutonium on the resin, is the number of equivalents of plutonium absorbed by the resin divided by the total capacity of the column. X{sub S}, the equivalent fraction of plutonium in solution, is the equivalent concentration of plutonium divided by the total equivalent concentration of cations in solution. C{sub R} is the total capacity of the resin in milli-equivalents per gram of dry resin. Recommendations have been made for the application and operation of ion-exchange columns in the Plutonium-Extraction Plant. (author)

Electroanalytical studies of uranium, neptunium, and plutonium ions in solutions

International Nuclear Information System (INIS)

Yoshida, Zenko; Aoyagi, Hisao; Kihara, Sorin

1989-01-01

Redox behavior of uranium, neptunium, and plutonium ions, whose oxidation states in acid solutions are between (VI) and (III), were investigated by flow-coulometry with a column electrode of glassy carbon fibers as well as ordinary voltammetry with a rotating disc electrode. Based on current-potential curves the electrode processes were elucidated taking their disproportionation and/or complexation reactions into account. The flow-coulometry, which provides rapid and quantitative electrolysis, was applied to such analytical purposes as follows; the determination of uranium and plutonium in the solution or the solid with discerning their oxidation states, the preparation of species in a desired oxidation state, even in an unstable state which cannot be prepared by ordinary procedure, and the separation of trace amount of uranium in solutions by the electrodeposition of its hydroxide

Treatment of Uranium and Plutonium solutions generated in Atalante by R and D activities

International Nuclear Information System (INIS)

Lagrave, H.; Beretti, C.; Bros, P.

2008-01-01

The Atalante complex operated by the 'Commissariat a l'Energie Atomique' (Cea) consolidates research programs on actinide chemistry, processing for recycling spent fuel, and fabrication of actinide targets for innovative concepts in future nuclear systems. In order to produce mixed oxide powder containing uranium, plutonium and minor actinides and to deal with increasing flows in the facility, a new shielded line will be built and is expected to be operational by 2012. Its main functions will be to receive, concentrate and store solutions, purify them, ensure co-conversion of actinides and conversion of excess uranium. (authors)

Treatment of Uranium and Plutonium solutions generated in Atalante by R and D activities

Energy Technology Data Exchange (ETDEWEB)

Lagrave, H.; Beretti, C.; Bros, P. [CEA Rhone Valley Research Center, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France)

2008-07-01

The Atalante complex operated by the 'Commissariat a l'Energie Atomique' (Cea) consolidates research programs on actinide chemistry, processing for recycling spent fuel, and fabrication of actinide targets for innovative concepts in future nuclear systems. In order to produce mixed oxide powder containing uranium, plutonium and minor actinides and to deal with increasing flows in the facility, a new shielded line will be built and is expected to be operational by 2012. Its main functions will be to receive, concentrate and store solutions, purify them, ensure co-conversion of actinides and conversion of excess uranium. (authors)

The determination of phosphorus in uranium minerals and resulting solutions; Determinacion de fosforo en minerales de uranio y soluciones procedentes de su beneficio

Energy Technology Data Exchange (ETDEWEB)

Petrement Eguiluz, J C; Rarellada Bellod, R; Fernandez Cellini, R

1964-07-01

Interferences of several elements present in Spanish uranium minerals in the phosphorus determination by the spectrophotometrical method of the molibdovanada te phosphoric acid are studied. A method is described with a previous separation of these element by a cationic resin. This method is successfully applied to the phosphorus determination in acid or alkaline lixiviation solutions of uranium minerals, as well as in the evaluates of ion exchange resins used used technically for the concentration of solutions with a low uranium content. (Author) 11 refs.

Non-Invasive Acoustic-Based Monitoring of Heavy Water and Uranium Process Solutions

Energy Technology Data Exchange (ETDEWEB)

Pantea, Cristian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinha, Dipen N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lakis, Rollin Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beedle, Christopher Craig [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Davis, Eric Sean [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-10-20

This presentation includes slides on Project Goals; Heavy Water Production Monitoring: A New Challenge for the IAEA; Noninvasive Measurements in SFAI Cell; Large Scatter in Literature Values; Large Scatter in Literature Values; Highest Precision Sound Speed Data Available: New Standard in H/D; ~400 pts of data; Noninvasive Measurements in SFAI Cell; New funding from NA241 SGTech; Uranium Solution Monitoring: Inspired by IAEA Challenge in Kazakhstan; Non-Invasive Acoustic-Based Monitoring of Uranium in Solutions; Non-Invasive Acoustic-Based Monitoring of Uranium in Solutions; and finally a summary.

Recent studies of uranium and plutonium chemistry in alkaline radioactive waste solutions

International Nuclear Information System (INIS)

King, William D.; Wilmarth, William R.; Hobbs, David T.; Edwards, Thomas B.

2008-01-01

Solubility studies of uranium and plutonium in a caustic, radioactive Savannah River Site tank waste solution revealed the existence of uranium supersaturation in the as-received sample. Comparison of the results to predictions generated from previously published models for solubility in these waste types revealed that the U model poorly predicts solubility while Pu model predictions are quite consistent with experimental observations. Separate studies using simulated Savannah River Site evaporator feed solution revealed that the known formation of sodium aluminosilicate solids in waste evaporators can promote rapid precipitation of uranium from supersaturated solutions

Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

International Nuclear Information System (INIS)

Souza, J.A.B.; Durazzo, M.

2010-01-01

IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 gU/cm 3 by using the U 3 Si 2 -Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 gU/cm 3 for the U 3 Si 2 -Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian-Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)

Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

Energy Technology Data Exchange (ETDEWEB)

Souza, Jose Antonio Batista de; Durazzo, Michelangelo, E-mail: jasouza@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 g U/c m3 by using the U{sub 3}Si{sub 2}-Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 g U/c m3 for the U{sub 3}Si{sub 2}-Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian- Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)

Potentiometric determination of uranium in simulated Purex Process solutions by acidiometry

International Nuclear Information System (INIS)

Cohen, V.H.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A. de

1983-01-01

A potentiometric methods for sequential free acidity and uranium determination in simulated Purex Process solutions is described. An oxalate solution or a mixture of fluoride-oxalate pellets were used as complexing agent for free titration. Following this first equivalent point, uranium is determined-by indirect titration of H + liberated in the peruanate reaction. Some elements present in the standard fuel elements with a burn-up of 33.000 Mwd/t, neutron flux of 3,2 x 10 13 n.cm -2 .s -1 and cooling time of two years were considered as interfering elements in uranium analyses. As a substitute of Pu-IV, Th(NO 3 ) 4 solution was used. The method can be applied to aqueous and organic (TBP/diluent) solutions with 2% precision and 2% accuracy. (Autor) [pt

Potentiometric determination of uranium in simulated Purex Process solutions by acidiometry

Energy Technology Data Exchange (ETDEWEB)

Cohen, V H; Matsuda, H T; Araujo, B.F. de; Araujo, J.A. de

1984-01-01

A potentiometric methods for sequential free acidity and uranium determination in simulated Purex Process solutions is described. An oxalate solution or a mixture of fluoride-oxalate pellets were used as complexing agent for free titration. Following this first equivalent point, uranium is determined-by indirect titration of H/sup +/ liberated in the peruanate reaction. Some elements present in the standard fuel elements with a burn-up of 33.000 Mwd/t, neutron flux of 3,2 x 10/sup 13/n.cm/sup -2/.s/sup -1/ and cooling time of two years were considered as interfering elements in uranium analyses. As a substitute of Pu-IV, Th(NO/sub 3/)/sub 4/ solution was used. The method can be applied to aqueous and organic (TBP/diluent) solutions with 2% precision and 2% accuracy. (Autor).

Uranium mining and production of concentrates in India

International Nuclear Information System (INIS)

Bhasin, J.L.

1997-01-01

In order to meet the uranium requirements for the atomic power programme of the country, uranium deposits were explored, mined and concentrates were produced indigenously. The geology of the areas, mode of entries and the various extraction methods deployed in different mines with their constraints are described. The various equipments used in mining and processing activities are elaborated. The flow sheets for processing the uranium ore and that of the effluent treatment plant are given in detail. The future plans of the company for undertaking the new projects to meet the demand of uranium requirement for the increasing nuclear power programme are given. (author). 18 figs

Recovery of uranium from lignites

International Nuclear Information System (INIS)

Hurst, F.J.

1980-01-01

Uranium in raw lignite is associated with the organic matter and is readily soluble in acid (and carbonate) solutions. However, beneficiation techniques were not successful for concentrating the uranium or removing part of the reagent-consuming materials. Once the lignite was heated, the uranium became much less soluble in both acid and carbonate solutions, and complete removal of carbon was required to convert it back to a soluble form. Proper burning improves acid-leaching efficiency; that is, it reduces the reagent consumption and concentrates the uranium, thereby reducing plant size for comparable uranium throughput, and it eliminates organic fouling of leach liquors. Restrictions are necessary during burning to prevent the uranium from becoming refractory. The most encouraging results were obtained by flash-burning lignite at 1200 to 1300 0 C and utilizing the released SO 2 to supplement the acid requirement. The major acid consumers were aluminum and iron

Study and application of new chelating resin to recovery uranium from in-situ leach solution with high content saline chloride ion

International Nuclear Information System (INIS)

Zhang Jianguo; Qiu Yueshuang; Feng Yu; Deng Huidong; Zhao Chaoya

2014-01-01

Research on the adsorption and elution property of D814 chelating resin was carried out aiming at the difficult separation of uranium from high content saline chloride ion in situ leach liquor and the adsorption mechanism is also discussed. Influence factors such as contact time, pH value, Ca"2"+, Mg"2"+ and Cl"- concentration etc. to the resin adsorption were studied. Experimental results show that adsorption rate is lowly which need 6h to arrive at the adsorption equilibrium. The resin adsorption uranium pH in the solution is from l.33 to 9. When total salinity is over 20 g/L, calcium ion, and magnesium ion is about 3 g/L, there are no big influence on resin adsorption capacity. The resin has good chloride ion resistance. When chloride ion is over 60 g/L, it is no influence on resin adsorption uranium. Column experiment results indicate that ratio of saturation volume to break-through point volume is l.82, resin saturation uranium capacity is 40.5 mg. U/_g_(_∓_)_R. When elution volume bed number is 23, the eluted solution uranium concentration is below 80 mg/L. The elution rate of the uranium is 96.2%. (authors)

Occurrence forms of uranium in the production solutions in the areas of underground leaching of epigenetic uranium deposits

International Nuclear Information System (INIS)

Serebrennikov, V.S.; Dorofeeva, V.A.

1980-01-01

Redox, acid-basic features of solutions (Eh changes from + 50 to 650 mV, pH from 7.5 to 1.5) and their chemical composition are studied in the process of hydrogeochemical investigations at the areas of underground leaching (UL) of epigenetic uranium deposits. It is shown that at studied areas of UL under neutral and weakly acidic conditions up to (pH 6.0-5.8), carbonate complexes of uranyl are the prevailing form of uranium existence in the solution, and sulfate complexes prevail under more acidic conditions. A supposition is made that it is expedient to process separate ore blocks with increased carbonate contents, particularly with oxidant additions under near-neutral acid-basic conditions (pH 7.2-6.8) with the use of weakly acid pumping solutions, which act (at the expense of their interaction with carbonates of ore-containing rocks) for enrichment of working solutions with HCO 3 - and CO 3 2- ions, promoting uranium transfer into solution

Uranium recovery from phosphate rocks concentrated

International Nuclear Information System (INIS)

Azevedo, M.F. de.

1986-01-01

The reserves, geological data, chemical data and technical flowsheet from COPEBRAS and Goiasfertil ores are described, including the process of mining ore concentration. Samples of Goiasfertil ores are analysed by gravimetric analysis, for phosphate, and spectrofluorimetry for uranium. (author)

Investigation of Great Basin big sagebrush and black greasewood as biogeochemical indicators of uranium mineralization. Final report. National Uranium Resource Evaluation

International Nuclear Information System (INIS)

Diebold, F.E.; McGrath, S.

1982-11-01

The effects of varying phosphate concentrations in natural aqueous systems upon the uptake of uranium by big sagebrush (Artemesia tridentata subsp. tridentata) and black greasewood (Sarcobatus vermiculatus (Hook) Torr.) were investigated. Two separate growth experiments with five drip-flow hyroponic units were used and plant seedlings were grown for 60 days in solutions of varying phosphate and uranium concentrations. Successful growth experiments were obtained only for big sagebrush; black greasewood did not sustain sufficient growth. The phosphate concentration of the water did affect the uptake of uranium by the big sagebrush, and this effect is most pronounced in the region of higher concentrations of uranium in the water. The ratio of the concentration of uranium in the plant to that in the water was observed to decrease with increasing uranium concentration in solution. This is indicative of an absorption barrier in the plants. The field data shows that big sagebrush responds to uranium concentrations in the soil water and not the groundwater. The manifestation of these results is that the use of big sagebrush as a biogeochemical indicator of uranium is not recommended. Since the concentration of phosphate must also be knwon in the water supplying the uranium to the plant, one should analyze this natural aqueous phase as a hydrochemical indicator rather than the big sagebrush

Spectrophotometric titrations: Application to the determination of some elements in uranium solutions

International Nuclear Information System (INIS)

L'Her, M.

1967-01-01

The aim of this work is the application of spectrophotometric titrations to the analysis of uranium-containing solutions. We have been led to examine the general principles involved in these titrations, and we give a brief outline of these principles. In the first part we deal therefore with spectrophotometric titrations from a general point of view, examining their fundamental principle, their practical execution as well as the various possibilities of the method. The advantage of the titration are examined, in particular that of lending itself simultaneous determination of two species. The possibility of applying these spectrophotometric titrations to the analysis of uranium-containing solutions is the subject of the second part of this report: the dosage of a few species in uranium (VI) solutions is described. To this second part is added an experimental appendix consisting of a description of the apparatus, as well as of the operational techniques used for certain titrations, in particular those involving solutions containing uranium. (author) [fr

Process for enriching uranium from seawater

International Nuclear Information System (INIS)

Heitkamp, D.; Inden, P.

1982-01-01

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

Uranium concentrations in human bone

International Nuclear Information System (INIS)

Schlenker, R.A.; Oltman, B.G.

1981-01-01

The uranium concentration in bone from an individual injected with 239 Pu has been determined, using the fission-track method. The data are consistent with those reported about 10 years ago by Welford and Baird for New York City area residents and by Hamilton in England. They are at variance with the more recent data of Welford et al

Assessment of the total uranium concentration in surface and underground water samples from the Caetite region, Bahia, Brazil

International Nuclear Information System (INIS)

Silva, Julia Grasiela Batista; Geraldo, Luiz Paulo; Yamazaki, Ione Makiko

2011-01-01

At the region of Caetite, BA, it is located the largest uranium mine in exploration at present days in Brazil. During the uranium extraction process, it may be having an environmental contamination by this heavy metal due to rain water and other natural transport mechanism, with potential exposition risk to the local population. The aim of this work was to investigate the total uranium concentration in surface and underground water samples collected at the Caetite region, using the nuclear track registration technique (SSNTD) in a polycarbonate plastic. A 100 mL volume of water samples were initially treated in 10 mL of HNO 3 (PA) and concentrated by evaporation at a temperature around 80 deg C. The resulting residue was diluted to a total volume of 25 mL without pass it to a filter. About 10 μL of this solution was deposited on the plastic detector surface (around 1.0 cm 2 area) together with 5 μL of a Cyastat detergent solution (5%) and evaporated under an infrared lamp. All the resulting deposits of non volatile constituents were irradiated, together with a uranium standard sample, at the IPEN-IEA-R1 (3.5 MW) nuclear reactor for approximately 3 min. After irradiations, chemical etching of the plastic detectors was carried out at 60 deg C, for 65 min. in a NaOH (6N) solution. The fission tracks were counted scanning all the deposit area of the polycarbonate plastic detector with a system consisting of an optical microscope together with a video camera and TV monitor. The average values of uranium concentrations obtained in this work ranged from (0.95±0.19) μg.L -1 to (25.60±3.3) μg.L -1 . These results were compared to values reported in the literature for water samples from other regions and discussed in terms of safe limits recommended by WHO -World Health Organization and CONAMA - Conselho Nacional do Meio Ambiente. (author)

Assessment of the total uranium concentration in surface and underground water samples from the Caetite region, Bahia, Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, Julia Grasiela Batista; Geraldo, Luiz Paulo [Centro Universitario da Fundacao Educacional de Barretos (UNIFEB), (SP) (Brazil); Yamazaki, Ione Makiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

At the region of Caetite, BA, it is located the largest uranium mine in exploration at present days in Brazil. During the uranium extraction process, it may be having an environmental contamination by this heavy metal due to rain water and other natural transport mechanism, with potential exposition risk to the local population. The aim of this work was to investigate the total uranium concentration in surface and underground water samples collected at the Caetite region, using the nuclear track registration technique (SSNTD) in a polycarbonate plastic. A 100 mL volume of water samples were initially treated in 10 mL of HNO{sub 3} (PA) and concentrated by evaporation at a temperature around 80 deg C. The resulting residue was diluted to a total volume of 25 mL without pass it to a filter. About 10 {mu}L of this solution was deposited on the plastic detector surface (around 1.0 cm{sup 2} area) together with 5 {mu}L of a Cyastat detergent solution (5%) and evaporated under an infrared lamp. All the resulting deposits of non volatile constituents were irradiated, together with a uranium standard sample, at the IPEN-IEA-R1 (3.5 MW) nuclear reactor for approximately 3 min. After irradiations, chemical etching of the plastic detectors was carried out at 60 deg C, for 65 min. in a NaOH (6N) solution. The fission tracks were counted scanning all the deposit area of the polycarbonate plastic detector with a system consisting of an optical microscope together with a video camera and TV monitor. The average values of uranium concentrations obtained in this work ranged from (0.95{+-}0.19) {mu}g.L{sup -1} to (25.60{+-}3.3) {mu}g.L{sup -1}. These results were compared to values reported in the literature for water samples from other regions and discussed in terms of safe limits recommended by WHO -World Health Organization and CONAMA - Conselho Nacional do Meio Ambiente. (author)

Recovery of uranium from biological adsorbents - desorption equilibrium

International Nuclear Information System (INIS)

Tsezos, M.

1984-01-01

Results are presented of the experimental investigations of uranium elution and reloading for the waste inactive biomass of Rhizopus arrhizus. The experimental data and the analysis of the present work suggest the following conclusions: recovery of uranium that has been taken up by R. arrhizus is possible by elution; of the six elution systems examined, sodium bicarbonate solutions appear to be the most promising because they can effect near complete uranium recovery and high uranium concentration factors; the bicarbonate solution causes the least damage to the biomass; solid-to-liquid ratios in bicarbonate elution systems can exceed 120:1 (mg:mL) for a 1N NaHCO 3 solution, with almost complete uranium recovery and eluate uranium concentrations of over 1.98 x 10 4 mg/L; mineral acids, although good elution agents, result in substantial damage to the biomass thus limiting the biomass reuse potential; sulfate ions in the elutions solution limit the elution potential of the biomass, possibly by conferring novel crystallinity to the cell wall chitin network and confining inside the chitin network more biosorbed uranium

Determination of uranium concentration in an ore sample using laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Kim, Y.-S.; Han, B.-Y.; Shin, H.S.; Kim, H.D.; Jung, E.C.; Jung, J.H.; Na, S.H.

2012-01-01

Laser-induced breakdown spectroscopy (LIBS) has been recognized as a promising technique for analyzing sensitive nuclear materials such as uranium, plutonium, and curium in a high-radiation environment, especially since the implementation of IAEA (International Atomic Energy Agency) safeguards. The uranium spectra of ore samples were quantitatively analyzed prior to analyzing sensitive materials in the nuclear industry. The purpose of this experiment is to extract quantitative information about the uranium in a uranium ore using a standard addition approach. The uranium ore samples containing different concentrations of U were prepared by mixing raw ore powder with natural uranium oxide powders. Calibration sets of 0.2, 0.4, 0.6, 0.8 and 1.0 wt.% uranium concentrations within the uranium ore sample were achieved. A pulsed and Q-switched Nd:YAG laser at a wavelength of 532 nm was used as a light source. An echelle spectrometer that covers a 190–420 nm wavelength range is used to generate a calibration curve and determine the detection limit of uranium in the ore matrix. The neutral atomic-emission peak at a wavelength of 356.659 nm indicated a detection limit of ∼ 158 ppm for uranium, and the uranium concentration was determined in a raw ore sample that has an unknown quantity of uranium. - Highlights: ► The feasibility of LIBS application to monitor uranium element was carried out. ► The detection limit of U in ore was determined by a standard additional approach. ► Quantitative analyses of U concentration in a natural uranium ore were performed.

Study of Uranium Concentrations in Water and Organic Material from Streams in Sweden

International Nuclear Information System (INIS)

Ek, J.

1981-12-01

The purpose of the investigation has been to study how uranium concentrations in stream water and organic material are related to various geological parameters such as rock types, average uranium content and radioactivity, fracturing, leachability of uranium from the bedrock, occurrence of uranium mineralisations and thickness and type of Quarternary deposits. The investigation has also taken account of the effects of environmental factors such as climate , precipitation, height above sea level and topography. The background concentration of uranium in organic stream sediment varies from 1 ppm to 45 ppm, with a background value of 10 ppm for all 14 areas considered together. The threshold value for organic stream material varies from 3 ppm U to 303 ppm U with a threshold value of 133 ppm U for all 14 areas considered together. For water, the background concentration varies between the 5 areas from 0.2 ppb U to 0.7 ppb U with a background value of 0.4 ppb U for all 5 areas together. The threshold value varies from 0.3 ppb U to 5.2 ppb U with a threshold value of 2.9 ppb U for all 5 areas together. An investigation of the correlation between uranium concentrations in water and organic stream material from one and the same sampling point shows a positive correlation for high concentrations, but the correlation becomes successively less significant with lower concentrations. Uranium concentrations in organic stream material and water are positively correlated with the following geological parameters:1) Background concentrations of uranium in the bedrock. 2) Abundance of fractures in the bedrock. 3) Leachability of uranium from the bedrock. 4) Presence of uranium mineralisations. For organic stream material, this positive correlation is obtained for both high and low uranium concentrations whereas for water it occurs only with high concentrations. In areas of broken topography and high relief, there is a more clearly defined correlation to the bedrock than in areas of

Proserpine - plutonium 239 - Proserpine - uranium 235 - comparison of experimental results; Proserpine - plutonium 239 - proserpine - uranium 235 - comparaison de resultats experimentaux

Energy Technology Data Exchange (ETDEWEB)

Brunet, J P; Caizergues, R; Clouet D' Orval, Ch; Kremser, J; Moret-Bailly, J; Verriere, Ph [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The Proserpine homogeneous reactor is constituted by a tank, 25 cm dia, 30 cm high, surrounded by a composite reflector made of beryllium oxide and graphite. In this tank can be made critical plutonium or 90 per cent enriched uranium solutions, the fissile substances being in the form of a dissolved salt. In varying the concentration of the solution, critical masses were studied as a function of the level of the liquid in the tank. The minimum critical mass is 256 {+-} 2 grs for plutonium and 409 {+-} 3 grs for uranium 235. In the range of the critical concentrations which were studied, the neutronic properties of fissionable solutions of plutonium and enriched uranium were compared for identical geometries. (authors) [French] Proserpine est un reacteur homogene comportant une cuve de diametre 25 cm, de hauteur 30 cm, entouree d'un reflecteur composite d'oxyde de beryllium et de graphite. On y a rendu critiques des solutions de plutonium ou d'uranium enrichi a 90 pour cent, le produit fissile se trouvant sous la forme d'un sel dissous. En faisant varier la concentration de la solution, on a etudie les masses critiques en fonction de la hauteur du liquide dans la cuve. La masse- critique minimum est, pour le plutonium de 256 {+-} 2 g, pour l'uranium 235 de 409 {+-} 3 g. Dans la gamme des concentrations critiques etudiees, on a compare, dans des conditions de geometrie identique, les proprietes neutroniques des solutions fissiles de plutonium et d'uranium enrichi. (auteurs)

Extraction behavior of uranium(VI) with polyurethane foam

International Nuclear Information System (INIS)

Tingchia Huang; Donghwang Chen; Muchang Shieh; Chingtsven Huang

1992-01-01

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

Uranium and radium content in the soil solutions of the south-western part of Belarus

International Nuclear Information System (INIS)

Sokolik, G.A.; Ovsyannikova, S.V.; Vojnikova, E.V.; Popenya, M.V.

2008-01-01

The contents of uranium and radium in the pore soil solutions, which are the main chain in the geochemical and biological migration of the chemical elements, has been determined for the first time in Belarus. The control sites have been located outside the zone of Chernobyl fallout radionuclide contamination, that allowed evaluating the current background level of uranium and radium content in the soil solutions. The data on accumulation of the radioactive elements in the pore solutions give the opportunity to estimate the reserve of the radioactive elements in the migratory active forms in the soils. In the majority of soils studied, uranium content in the pore solution is higher than radium content, that points to the higher migratory ability of uranium. The direct correlation between content of fulvic acids' components in the soil solutions and accumulation of uranium in such solutions has been established. (authors)

Uranium concentrations in the water consumed by the resident population in the vicinity of the Lagoa Real uranium province, Bahia, Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, Luciana S. [State University of Bahia (UNEB), Campus Caetite, BA (Brazil); Pecequilo, Brigitte R.S.; Sarkis, Jorge; Nisti, Marcelo B., E-mail: brigitte@ipen.br, E-mail: jesarkis@ipen.br, E-mail: mbnisti@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The Lagoa Real Uranium Province, situated in South Central Bahia in the region of Caetite and Lagoa Real, is considered the most important monomineralic province of Brazil. The urban population who lives in the proximities of this uranium province in the cities of Caetite, Lagoa Real and Livramento uses public supply water, while the inhabitants of the rural area due to long terms of dry weather use water from wells, cisterns, small dams, reservoirs and dikes which are supplied with the rains. In this work it was determined the concentration of uranium in the water consumed by the rural and urban population living in the proximities of the Lagoa Real Uranium Province. The study comprehends 32 sampling spots spread throughout the region of interest. Samples were collected in January and July 2010, covering superficial, underground and public supply water from the region. The uranium concentrations were determined by an inductively coupled plasma mass spectrometer (ICP-MS). Preliminary results showed that the uranium concentrations in the water from the Lagoa Real Uranium Province varied from 0.064 {+-} 0.005 {mu}g.L{sup -1} to 90 {+-} 1,5 {+-}g.L{sup -1}. It was observed that only two of them obtained values higher than the World Health Organization's recommended limit (2011) of 30 {mu}g.L{sup -1} for maximum uranium concentration in the water for human consumption. For a conclusive evaluation, the uranium concentrations results will be analyzed together with total alpha and beta concentrations determined elsewhere for the same samples. (author)

Uranium concentrations in the water consumed by the resident population in the vicinity of the Lagoa Real uranium province, Bahia, Brazil

International Nuclear Information System (INIS)

Silva, Luciana S.; Pecequilo, Brigitte R.S.; Sarkis, Jorge; Nisti, Marcelo B.

2011-01-01

The Lagoa Real Uranium Province, situated in South Central Bahia in the region of Caetite and Lagoa Real, is considered the most important monomineralic province of Brazil. The urban population who lives in the proximities of this uranium province in the cities of Caetite, Lagoa Real and Livramento uses public supply water, while the inhabitants of the rural area due to long terms of dry weather use water from wells, cisterns, small dams, reservoirs and dikes which are supplied with the rains. In this work it was determined the concentration of uranium in the water consumed by the rural and urban population living in the proximities of the Lagoa Real Uranium Province. The study comprehends 32 sampling spots spread throughout the region of interest. Samples were collected in January and July 2010, covering superficial, underground and public supply water from the region. The uranium concentrations were determined by an inductively coupled plasma mass spectrometer (ICP-MS). Preliminary results showed that the uranium concentrations in the water from the Lagoa Real Uranium Province varied from 0.064 ± 0.005 μg.L -1 to 90 ± 1,5 ±g.L -1 . It was observed that only two of them obtained values higher than the World Health Organization's recommended limit (2011) of 30 μg.L -1 for maximum uranium concentration in the water for human consumption. For a conclusive evaluation, the uranium concentrations results will be analyzed together with total alpha and beta concentrations determined elsewhere for the same samples. (author)

Investigation of Artemisia tridentata as a biogeochemical uranium indicator

Energy Technology Data Exchange (ETDEWEB)

Diebold, F E; McGrath, S [Montana Coll. of Mineral Science and Technology, Butte (USA)

1985-01-01

Hydroponic experiments were conducted with seedlings of Artemisia tridentata subsp. tridentata (big sagebrush) to test the effect of the phosphate speciation of uranium in solution on its uptake by big sagebrush. No single complex could be identified as being preferentially taken up by the plant, but the varying aqueous phosphate concentrations did affect uranium uptake by the plants at the higher uranium concentrations in solution. The data also substantiate the tendency for uranium to behave as an essential element in this plant species. The implications for the use of Artemisia tridentata as a biogeochemical uranium indicator are discussed.

Multisensor system for determination of iron(II), iron(III) and uranium(VI) in complex solutions

International Nuclear Information System (INIS)

Legin, A.V.; Seleznev, B.L.; Rudnitskaya, A.M.; Vlasov, Yu.G.

1998-01-01

The aim of the present paper is the development and analytical evaluation of a multisensor system for determination of low content of iron(II), iron(III) and uranium(VI) in complex aqueous media. Sensor array included sensors on the basis of chalcogenide vitreous materials with redox and ionic cross-sensitivities, crystalline silver sulphide electrode, noble metal electrodes Pt, Au, Ag and redox sensor on the basis of oxide glass. Potentiometric measurements have been taken in a conventional electrochemical cell vs. a standard Ag/AgCl reference electrode. All measurements have been taken at room temperature. Calibration solutions contained UO 2 (NO 3 ) 2 in concentration range 10 -6 -1,610 -5 mol/L, K 3 Fe(CN) 6 and K 4 Fe(CN) 6 or FeSO 4 (NH 4 ) 2 SO 4 and FeCl 3 , with the ratio of Fe(II)/Fe(III) concentration from 100:1 to 1:100, the total concentration of Fe was 10 -4 and 10 -5 mol/L. All solutions have been made on the background electrolyte of calcium and magnesium chlorides and sulphates with the fixed content of 5-27 mmol/L of each component which is a typical one for groundwater or mining water. Sensor potentials have been processed by a back-propagation artificial neural net. Average error of determination of Fe(II) and Fe(III) is about 20 %, of uranium(VI) - 40 %. It was found that sensitivity of the sensor array to iron and uranium is irrespective of the chemical form of these species

Management of wastes from the refining and conversion of uranium ore concentrate to uranium hexafluoride

International Nuclear Information System (INIS)

1981-01-01

This report is the outcome of an IAEA Advisory Group Meeting on ''Waste Management Aspects in Relation to the Refining of Uranium Ore Concentrates and their Conversion to Uranium Hexafluoride'', which was held in Vienna from 17 to 21 December 1979. The report summarizes the main topics discussed at the meeting and gives an overview of uranium refining processes, being used in nuclear industry. The meeting was organized by the International Atomic Energy Agency, Radioactive Waste Management Section

PROCESS FOR RECOVERY OF URANIUM VALUES FROM IMPURE SOLUTIONS THEREOF

Science.gov (United States)

Kilner, S.B.

1959-11-01

A process is presented for the recovery of uraninm values from impure solutions which are obtained, for example, by washing residual uranium salt or uranium metal deposits from stainless steel surfaces using an aqueous or certain acidic aqueous solutions. The solutions include uranyl and oxidized iron, chromium, nickel, and copper ions and may contain manganese, zinc, and silver ions. In accordance with one procedure. the uranyl ions are reduced to the uranous state, and the impurity ions are complexed with cyanide under acidic conditions. The solution is then treated with ammonium hydroxide or alkali metal hydroxide to precipitate uranous hydroxide away from the complexed impurity ions in the solution. Alternatively, an excess of alkali metal cyanide is added to the reduced solution until the solution becomes sufficiently alkaline for the uranons hydroxide to precipitate. An essential feature in operating the process is in maintaining the pH of the solution sufficiently acid during the complexing operation to prevent the precipitation of the impurity metal hydroxides.

Uranium concentrations in sediments of the Suez Canal

International Nuclear Information System (INIS)

Ibrahiem, N.M.; Pimpl, M.

1994-01-01

Suez Canal bottom sediment samples have been analyzed by alpha-spectrometry for the measurement of uranium. This method is based on the extraction of uranium with trioctylphosphine oxide/cyclohexane (TOPO) followed by reextraction and separation on anion exchange resins, and finally electrodeposition. The α-activity of 238 U and 234 U were measured by surface barrier detectors, in Bq/kg dry weight. The obtained results were compared with concentrations determined by γ measurements. The results point to a state of disequilibrium between 238 U and RaeU (radium equivalent uranium) which is attributed to the escape of radon. (author)

Dissolution study of thorium-uranium oxides in aqueous triflic acid solutions

Energy Technology Data Exchange (ETDEWEB)

Bulemela, E.; Bergeron, A.; Stoddard, T. [Canadian Nuclear Laboratories - CNL, 286 Plant Rd., Chalk River, Ontario, K0J 1J0 (Canada)

2016-07-01

The dissolution of sintered mixed oxides of thorium with uranium in various concentrations of trifluoromethanesulfonic (triflic) acid solutions was investigated under reflux conditions to evaluate the suitability of the method. Various fragment sizes (1.00 mm < x < 7.30 mm) of sintered (Th,U)O{sub 2} and simulated high-burnup nuclear fuel (SIMFUEL) were almost completely dissolved in a few hours, which implies that triflic acid could be used as an alternative to the common dissolution method, involving nitric acid-hydrofluoric acid mixture. The influence of acid concentration, composition of the solids, and reaction time on the dissolution yield of Th and U ions was studied using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The dissolution rate was found to depend upon the triflic acid concentration and size of the solid fragments, with near complete dissolution for the smallest fragments occurring in boiling 87% w/w triflic acid. The formation of Th and U ions in solution appears to occur at the same rate as the triflic acid simultaneously reacts with the constituent oxides as evidenced by the results of a constant U/Th concentration ratio with the progress of the dissolution. (authors)

Purification and concentration of uranium-bearing solutions at the plants of the Societe industrielle des minerais de l'Ouest

International Nuclear Information System (INIS)

Vollerin, G.

1980-01-01

The author describes the various processes for purification of uranium-bearing solutions used at the plants of the Societe industrielle des minerais de l'Ouest (SIMO) from their commissioning up to the present time, together with the purification circuit adopted at the two plants at present operating in Niger. (author)

Adsorption of uranium from aqueous solution using biochar produced by hydrothermal carbonization

International Nuclear Information System (INIS)

Zhi-bin Zhang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan; China University of Geosciences, Wuhan; Xiao-hong Cao; Yun-hai Liu; East China Institute of Technology, Fuzhou; Ping Liang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan

2013-01-01

The ability of biochar produced by hydrothermal carbonization (HTC) has been explored for the removal and recovery of uranium from aqueous solutions. The micro-morphology and structure of HTC were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The influences of different experimental parameters such as solution pH, initial concentration, contact time, ionic strength and temperature on adsorption were investigated. The HTC showed the highest uranium sorption capacity at initial pH of 6.0 and contact time of 50 min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir isotherm. The thermodynamic parameters, ΔGdeg(298 K), ΔHdeg and ΔSdeg were determined to be -14.4, 36.1 kJ mol -1 and 169.7 J mol -1 K -1 , respectively, which demonstrated the sorption process of HTC towards U(VI) was feasible, spontaneous and endothermic in nature. The adsorbed HTC could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 2.0 g HTC. (author)

Operating conditions of T.B.P. line uranium purification plant, for uranium dioxide production

International Nuclear Information System (INIS)

Vardich, R.N.; La Gamma, A.M.; Anasco, R.; Soler, S.M.G. de; Isnardi, E.; Gea, V.; Chiaraviglio, R.; Matyjasczyk, E.; Aramayo, R.

1992-01-01

In this contribution are presented the operative conditions and the results obtained step of the Uranium dioxide production plant of Argentina. The refining step involve the Uranium concentrate dissolution, the silica ageing, the filtration and liquid - liquid extraction with n-tributyl phosphate solution in kerosene. The established operative conditions allow to obtain Uranyl nitrate solutions of nuclear purity in industrial scale. (author)

Recovery of uranium mineral from Liaoning Fengcheng ludwigite ore by gravity concentration

International Nuclear Information System (INIS)

Zhang Tao; Liang Haijun; Xue Xiangxin

2009-01-01

A laboratory research was carried out to recover uranium mineral from Liaoning Fengcheng ludwigite ore. Gravity concentration methods including hydroclone, spiral chute and shaking table were applied in this study. The results show that a concentrate with uranium grade of 0.216% and recovery of 44.24% could be produced from the feed of uranium content 0.006 3%. This research is helpful to comprehensive utilization of the mineral resources. Increasing further uranium mineral liberation degree is the key to improve separation effects. (authors)

Modeled atmospheric radon concentrations from uranium mines

Energy Technology Data Exchange (ETDEWEB)

Droppo, J.G.

1985-04-01

Uranium mining and milling operations result in the release of radon from numerous sources of various types and strengths. The US Environmental Protection Agency (EPA) under the Clean Air Act, is assessing the health impact of air emissions of radon from underground uranium mines. In this case, the radon emissions may impact workers and residents in the mine vicinity. To aid in this assessment, the EPA needs to know how mine releases can affect the radon concentrations at populated locations. To obtain this type of information, Pacific Northwest Laboratory used the radon emissions, release characteristics and local meterological conditions for a number of mines to model incremental radon concentrations. Long-term, average, incremental radon concentrations were computed based on the best available information on release rates, plume rise parameters, number and locations of vents, and local dispersion climatology. Calculations are made for a model mine, individual mines, and multiple mines. Our approach was to start with a general case and then consider specific cases for comparison. A model underground uranium mine was used to provide definition of the order of magnitude of typical impacts. Then computations were made for specific mines using the best mine-specific information available for each mine. These case study results are expressed as predicted incremental radon concentration contours plotted on maps with local population data from a previous study. Finally, the effect of possible overlap of radon releases from nearby mines was studied by calculating cumulative radon concentrations for multiple mines in a region with many mines. The dispersion model, modeling assumptions, data sources, computational procedures, and results are documented in this report. 7 refs., 27 figs., 18 tabs.

Modeled atmospheric radon concentrations from uranium mines

International Nuclear Information System (INIS)

Droppo, J.G.

1985-04-01

Uranium mining and milling operations result in the release of radon from numerous sources of various types and strengths. The US Environmental Protection Agency (EPA) under the Clean Air Act, is assessing the health impact of air emissions of radon from underground uranium mines. In this case, the radon emissions may impact workers and residents in the mine vicinity. To aid in this assessment, the EPA needs to know how mine releases can affect the radon concentrations at populated locations. To obtain this type of information, Pacific Northwest Laboratory used the radon emissions, release characteristics and local meterological conditions for a number of mines to model incremental radon concentrations. Long-term, average, incremental radon concentrations were computed based on the best available information on release rates, plume rise parameters, number and locations of vents, and local dispersion climatology. Calculations are made for a model mine, individual mines, and multiple mines. Our approach was to start with a general case and then consider specific cases for comparison. A model underground uranium mine was used to provide definition of the order of magnitude of typical impacts. Then computations were made for specific mines using the best mine-specific information available for each mine. These case study results are expressed as predicted incremental radon concentration contours plotted on maps with local population data from a previous study. Finally, the effect of possible overlap of radon releases from nearby mines was studied by calculating cumulative radon concentrations for multiple mines in a region with many mines. The dispersion model, modeling assumptions, data sources, computational procedures, and results are documented in this report. 7 refs., 27 figs., 18 tabs

Concentration factors of uranium mineralization in VII depositional cycle of Shuixigou group, lower-middle Jurassic at Wukurqi uranium deposit, Yili basin

International Nuclear Information System (INIS)

Liu Taoyong

2004-01-01

Starting with the analysis on uranium mineralization, this paper emphatically discusses factors related to uranium concentration in VII depositional cycle, such as the structure, the paleoclimate, the lithofacies-paleogeography, the lithology, the hydrogeology, the geochemistry, and the content of effective reductant. The author suggests that key factors of uranium migration and concentration at Wukurqi uranium deposit are the existence of ore-hosting formation (sand body), the long-term recharge of oxygen and uranium-bearing groundwater, the existence of effective reductant in ore-hosting formation

Spectrophotometric titrations: Application to the determination of some elements in uranium solutions; Les titrages spectrophotometriques: Application a la determination de quelques elements dans les solutions d'uranium

Energy Technology Data Exchange (ETDEWEB)

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

1967-01-01

The aim of this work is the application of spectrophotometric titrations to the analysis of uranium-containing solutions. We have been led to examine the general principles involved in these titrations, and we give a brief outline of these principles. In the first part we deal therefore with spectrophotometric titrations from a general point of view, examining their fundamental principle, their practical execution as well as the various possibilities of the method. The advantage of the titration are examined, in particular that of lending itself simultaneous determination of two species. The possibility of applying these spectrophotometric titrations to the analysis of uranium-containing solutions is the subject of the second part of this report: the dosage of a few species in uranium (VI) solutions is described. To this second part is added an experimental appendix consisting of a description of the apparatus, as well as of the operational techniques used for certain titrations, in particular those involving solutions containing uranium. (author) [French] Le but de ce travail est l'application des titrages spectrophotometriques a l'analyse des solutions uraniferes. Nous avons ete amenes a examiner les principes generaux de ces titrages, principes qu'il nous est apparu necessaire de rappeler. Dans une premiere partie nous traiterons donc d'une facon generale des titrages spectrophotometriques, en examinant leur principe fondamental, leur mise en oeuvre ainsi que les possibilites diverses de dosage. Nous examinerons aussi les avantages de la methode de titrage, en insistant notamment sur la possibilite de faire des dosages successifs. La possibilite d'application de ces titrages spectrophotometriques a l'analyse des solutions uraniferes sera le sujet de la deuxieme partie: nous y decrivons le dosage de quelques especes, dans les solutions d'uranium (VI). A cette deuxieme partie nous joindrons une annexe experimentale comportant une description de l'appareillage que

Accumulation of thorium and uranium by microbes. The effect of pH, concentration of metals, and time course on the accumulation of both elements using streptomyces levoris

International Nuclear Information System (INIS)

Tsuruta, Takehiko

2006-01-01

The accumulation of thorium and uranium by various microorganisms from a solution containing both metals at pH 3.5 was examined. Among the tested species, a high accumulation ability for thorium was exhibited by strains of gram-positive bacteria, such as Arthrobacter nicotianae, Bacillus megaterium, B. subtilis, Micrococcus luteus, Rhodococcus erythropolis, and Streptomyces levoris. Though uranium was accumulated in small amounts by most of microorganisms. A. nicotianae, S. flavoviridis, and S. levoris had relatively high uranium accumulation abilities. In these high performance thorium- and uranium-accumulating microorganisms, S. levoris, which accumulated the largest amount of uranium from the solution containing only uranium at pH 3.5, accumulated about 300 μmol thorium and 133 μmol uranium per gram dry weight of microbial cells from a solution containing both thorium and uranium at pH 3.5. The amount and time course of the thorium accumulation were almost unaffected by the co-existing uranium, while those of uranium were strongly affected by the co-existing thorium. The effects of pH, the thorium and uranium concentrations, and time course on both metal accumulations were also evaluated by numerical formulas. (author)

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

International Nuclear Information System (INIS)

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

1983-04-01

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

Contribution to the characterization of the ideality deviation of concentrated solutions of electrolytes: application to the case plutonium and uranium (IV) nitrates

International Nuclear Information System (INIS)

Charrin, N.

1999-01-01

The purpose of this work is to establish a base of binary data referring to the plutonium and uranium nitrates (IV) activity coefficients, which will permit to take account the medium effects in the process of liquid-liquid extraction set in action during the reprocessing of irradiated combustibles in a more scrupulous way. The first chapter sticks to establish the problematic of acquisition of actinides binary data at an oxidation state (IV) linked to two characteristics of this type of electrolyte its radioactive properties and its chemical properties. Its chemical properties bring us to define the fictitious binary data and to use an approach based on the thermodynamic concept of simple solutions, on the measurements of water activity of ternary or quaternary mixtures of the actinide, in nitric acid medium and on the binary data of nitric acid. The second chapter intended to propose reliable binary data concerning nitric acid. The validation of acquisition of fictitious binary data method suggested is undertaken. The electrolyte test is the thorium nitrate (IV). The very encouraging results has determined the carrying out of this work of research in that way. The third chapter is based on the experimental acquisition of uranium and plutonium nitrates (IV) binary data. It emphasises the importance given to the preparation of the studied mixtures which characteristics, very high actinide concentrations and low acidities, make them atypical solutions and without any referenced equivalents. The last chapter describes the exploitation which was made of the established binary data. The characteristic parameters of Pu(NO 3 ) 4 and U(NO 3 ) 4 of Pitzer model and of the specific interaction theory has been appraised. Then the application of' the concept of simple solutions to the calculation of the density or quaternary mixtures like Pu(NO 3 ) 4 / UO 2 (NO 3 ) 2 /HNO 3 / H 2 O was proposed. (author)

Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

Science.gov (United States)

Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

2009-03-01

During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

Predictive geochemical modeling of contaminant concentrations in laboratory columns and in plumes migrating from uranium mill tailings waste impoundments

International Nuclear Information System (INIS)

Peterson, S.R.; Martin, W.J.; Serne, R.J.

1986-04-01

A computer-based conceptual chemical model was applied to predict contaminant concentrations in plumes migrating from a uranium mill tailings waste impoundment. The solids chosen for inclusion in the conceptual model were selected based on reviews of the literature, on ion speciation/solubility calculations performed on the column effluent solutions and on mineralogical characterization of the contacted and uncontacted sediments. The mechanism of adsorption included in the conceptual chemical model was chosen based on results from semiselective extraction experiments and from mineralogical characterization procedures performed on the sediments. This conceptual chemical model was further developed and partially validated in laboratory experiments where assorted acidic uranium mill tailings solutions percolated through various sediments. This document contains the results of a partial field and laboratory validation (i.e., test of coherence) of this chemical model. Macro constituents (e.g., Ca, SO 4 , Al, Fe, and Mn) of the tailings solution were predicted closely by considering their concentrations to be controlled by the precipitation/dissolution of solid phases. Trace elements, however, were generally predicted to be undersaturated with respect to plausible solid phase controls. The concentration of several of the trace elements were closely predicted by considering their concentrations to be controlled by adsorption onto the amorphous iron oxyhydroxides that precipitated

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

Energy Technology Data Exchange (ETDEWEB)

Khajeh, Mostafa; Nemch, Tabandeh Karimi [Zabol Univ. (Iran, Islamic Republic of). Dept. of Chemistry

2014-07-01

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{sup -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.

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.

Uranium removal from water by five aquatic plants

International Nuclear Information System (INIS)

Hu Nan; Ding Dexin; Li Guangyue; Wang Yongdong; Li Le; Zheng Jifang

2012-01-01

Hydroponic solution culture experiments were conducted on the growth of Eichhornia crassipes, Lemna minor L, Azolla imbircata, Potamogeton crispus, and Alligator alternanthera Herb in water with 0.15, 1.50 and 15.00 mg . L -1 concentrations of uranium, and on the uranium removal from the water by the aquatic plants. For the 21 days of hydroponic solution culture experiments, Azolla imbircata exhibited the strongest resistance to uranium and its growth inhibition rates induced by the water with 0.15, 1.50 and 15.00 mg · L -1 concentrations of uranium were 4.56%, 2.48%, 6.79%, respectively, and the uranium removal rates from the water by the plant amounted to 94%, 97% and 92%, respectively. Further experiments revealed that the most uranium removal could be achieved when 7.5 g Azolla imbircata was grown in 1 L of water, and the time required for the plant to reduce the uranium concentration in water with 1.25, 2.50, 5.00 and 10.00 mg · L -l concentrations of uranium below that stipulated in the national emission standards of China were 17, 19, 23 and 25 days, respectively. The results have laid foundation for further studies of phytoremediation of uranium contaminated water. (authors)

Uranium(VI) speciation: modelling, uncertainty and relevance to bioavailability models. Application to uranium uptake by the gills of a freshwater bivalve

International Nuclear Information System (INIS)

Denison, F.H.

2004-07-01

The effects of varying solution composition on the interactions between uranium(VI) and excised gills of the freshwater bivalve Corbicula fluminea have been investigated in well defined solution media. A significant reduction in the uptake of uranium was observed on increasing the concentrations of the uranium complexing ligands citrate and carbonate. Saturation kinetics as a function of uranium concentration at a pH value of 5.0 were observed, indicating that the uptake of uranium is a facilitated process, probably involving one or several trans-membrane transport systems. A relatively small change in the uptake of uranium was found as a function of pH (factor of ca. 2), despite the extremely large changes to the solution speciation of uranium within the range of pH investigated (5.0 - 7.5). A comprehensive review of the thermodynamic data relevant to the solution composition domain employed for this study was performed. Estimates of the uncertainties for the formation constants of aqueous uranium(VI) species were integrated into a thermodynamic database. A computer program was written to predict the equilibrium distribution of uranium(VI) in simple aqueous systems, using thermodynamic parameter mean-values. The program was extended to perform Monte Carlo and Quasi Monte Carlo uncertainty analyses, incorporating the thermodynamic database uncertainty estimates, to quantitatively predict the uncertainties inherent in predicting the solution speciation of uranium. The use of thermodynamic equilibrium modelling as a tool for interpreting the bioavailability of uranium(VI) was investigated. Observed uranium(VI) uptake behaviour was interpreted as a function of the predicted changes to the solution speciation of uranium. Different steady-state or pre-equilibrium approaches to modelling uranium uptake were tested. Alternative modelling approaches were also tested, considering the potential changes to membrane transport system activity or sorption characteristics on

Fixation and separation of the elements thorium and uranium using anion exchange resins in nitrate solution

International Nuclear Information System (INIS)

Korgaonkar, V.

1967-10-01

The exchange of thorium and uranium between a strong base anion resin and a mixed water + ethanol solvent containing nitrate ions is studied. It is assumed that in the resin the thorium and uranium are fixed in the form of the complexes Th(NO 3 ) 6 2- and UO 2 (NO 3 ) 4 2- in solution these elements are present in the form of complexes having the general formula: Th(NO 3 ) 6-n n-2 and UO 2 (NO 3 ) 4-n n-2 It has been possible to deduce a law for the changes in the partition functions of thorium and uranium as a function of the concentrations of the various species in solution and of the complexing ion NO 3 . From this has been deduced the optimum operational conditions for separating a mixture of these two elements. Finally, in these conditions, the influence of a few interfering ions has been studied: Ba, Bi, Ce, La, Mo, Pb, Zr. The method proposed can be used either as a preparation, or for the dosage of thorium by a quantitative separation. (author) [fr

Determination of uranium metal concentration in irradiated fuel storage basin sludge using selective dissolution

International Nuclear Information System (INIS)

Delegard, C.H.; Sinkov, S.I.; Chenault, J.W.; Schmidt, A.J.; Pool, K.N.; Welsh, T.L.

2014-01-01

Irradiated uranium metal fuel was stored underwater in the K East and K West storage basins at the US Department of Energy Hanford Site. The uranium metal under damaged cladding reacted with water to generate hydrogen gas, uranium oxides, and spalled uranium metal particles which intermingled with other particulates to form sludge. While the fuel has been removed, uranium metal in the sludge remains hazardous. An expeditious routine method to analyze 0.03 wt% uranium metal in the presence of >30 wt% total uranium was needed to support safe sludge management and processing. A selective dissolution method was designed based on the rapid uranium oxide dissolution but very low uranium metal corrosion rates in hot concentrated phosphoric acid. The uranium metal-bearing heel from the phosphoric acid step then is rinsed before the uranium metal is dissolved in hot concentrated nitric acid for analysis. Technical underpinnings of the selective dissolution method, including the influence of sludge components, were investigated to design the steps and define the reagents, quantities, concentrations, temperatures, and times within the selective dissolution analysis. Tests with simulant sludge proved the technique feasible. Tests with genuine sludge showed a 0.0028 ± 0.0037 wt% (at one standard deviation) uranium metal analytical background, a 0.011 wt% detection limit, and a 0.030 wt% quantitation limit in settled (wet) sludge. In tests using genuine K Basin sludge spiked with uranium metal at concentrations above the 0.030 wt% ± 25 % (relative) quantitation limit, uranium metal recoveries averaged 99.5 % with a relative standard deviation of 3.5 %. (author)

Study on the treatment of waste waster containing uranium by organic modified vermiculite

International Nuclear Information System (INIS)

Liu Wenjuan; Zeng Yanhong

2012-01-01

The adsorption capability of uranium on organic modified Vermiculite was studied. The influence factors of the amount of adsorbent, initial pH, initial concentration of uranium and adsorption time have been investigated too. Through the orthogonal test, the primary factors of impacting the adsorption treatment can be obtained. Finally, the preliminary research and analysis on the principle adsorption of organic modified vermiculite test of uranium have been conducted. The results show that: Modifying Vermiculite by CTMAB makes Vermiculite adsorption capacity stronger when treating solution containing uranium. Combined flocculants with vermiculite to treat with low concentration of uranium solution has synergy, significantly enhancing its adsorption capacity. The impact factors of organic modified vermiculite's adsorption of uranium are adsorbent dosage, pH, initial concentration of uranium solution and adsorption time. The best adsorption pH is between 5∼6.5. (authors)

Investigation of uranium sorption from carbonate solutions by different ion exchange materials

International Nuclear Information System (INIS)

Nekrasova, N.A.; Kudryavtseva, S.P.; Milyutin, V.V.; Chuveleva, Eh.A.; Firsova, L.A.; Gelis, V.M.

2008-01-01

One studied the uranium sorption from the reference carbonate solutions based on the ion-exchange resins varying in the rank. The PFA-300, the A-560, the AB-17x8 highly basic anionites and the ampholytes (S-930, S-922, S-957, ANKB-35) were shown to manifest the best sorption characteristics as to U. One determined the dependences of the static exchange capacity of the PFA-300, the A-560 and the S-922 resins as to the uranium on the carbonate solution pH, as well as the absorbed uranium desorption conditions [ru

Application of solution-mineral equilibrium chemistry to solution mining of uranium ores

International Nuclear Information System (INIS)

Riese, A.C.; Popp, C.J.

1979-01-01

The tests described were undertaken to determine the extent to leach solution-rock interactions with uranium-bearing ore obtained from the Mariano Lake mine. Leach solutions of an acidic (H/sub 2/O/sub 4/-sulfuric acid) and basic (NaHCO/sub 3/-sodium bicarbonate) nature were tested, in addition to a leach solution containing potassium chloride and sulfuric acid (KCl/H/sub 2/SO/sub 4/). The latter solution was chosen in an attempt to equilibrate the aqueous phase with the rock-forming silicate minerals and minimize adverse effects such as clay formation, porosity loss, and lixiviant loss. 29 refs

Determination of trace concentration of uranium in soils by the nuclear track technique

International Nuclear Information System (INIS)

Islam, G.S.; Abdullah, M.N.A.

1998-04-01

Solid state nuclear track detector CR-39 has been used to estimate trace concentration of uranium in soil and sand samples from various places of Bangladesh. Uranium contents in soil samples have been found to vary from ∼3.79 to ∼8.63 ppm and in sand samples from ∼2.39 to ∼6.53 ppm. The mean concentration in soil and in sand samples were found to be ∼4.52 and ∼2.96 ppm respectively. The maximum uranium concentration in soil samples was observed in Sylhet while the uranium concentration of sand was found to be maximum in the sea beach of Cox's Bazar. The implication of results is briefly discussed in the paper. (author)

Uranium Rirang ore processing: extraction of uranium from Rirang ore digestion solution with tributyl phosphate

International Nuclear Information System (INIS)

Arief, E. R.; Zahardi; Susilaningtyas

1998-01-01

Uranium is extracted from Rirang ore acid digestion solution containing rare earths. A mixture of tributyl phosphate solvent and kerosene diluent is employed. Several parameters of solvent extraction have been studied included aqueous to organic phase ratio, H 2 O 2 reductor concentration and Tbp concentration in the solvent mixture, as well as the aqueous to organic phase ratio in the stripping process. The optimum conditions for the extraction step include the use of 25% H 2 O 2 (v/v), one to one aqueous to organic ratio, and 40% Tbp in kerosene. The extraction recovery for U, RE, Th, and PO 4 3 - are 99%, 4%, 70%, and 30%, respectively. The stripping step optimum conditions include the use of one to five organic to aqueous phase ratio 0.24 N HNO 3 . and the stripping recovery for U, RE, Th, and PO 4 3 - are 84%, 80%, 72%, and 83%, respectively

Paleozoic unconformities favorable for uranium concentration in northern Appalachian basin

International Nuclear Information System (INIS)

Dennison, J.M.

1986-01-01

Unconformities can redistribute uranium from protore rock as ground water moves through poorly consolidated strata beneath the erosion surface, or later moves along the unconformity. Groundwater could migrate farther than in present-day lithified Paleozoic strata in the Appalachian basin, now locally deformed by the Taconic and Allegheny orogenies. Several paleoaquifer systems could have developed uranium geochemical cells. Sandstone mineralogy, occurrences of fluvial strata, and reduzate facies are important factors. Other possibilities include silcrete developed during desert exposure, and uranium concentrated in paleokarst. Thirteen unconformities are evaluated to determine favorable areas for uranium concentration. Cambrian Potsdam sandstone (New York) contains arkoses and possible silcretes just above crystalline basement. Unconformities involving beveled sandstones and possible fluvial strata include Cambrian Hardyston sandstone (New Jersey), Cambrian Potsdam Sandstone (New York), Ordovician Oswego and Juniata formations (Pennsylvania and New York), Silurian Medina Group (New York), and Silurian Vernon, High Falls, and Longwood formations (New York and New Jersey). Devonian Catskill Formation is beveled by Pennsylvanian strata (New York and Pennsylvania). The pre-Pennsylvanian unconformity also bevels Lower Mississippian Pocono, Knapp, and Waverly strata (Pennsylvania, New York, and Ohio), truncates Upper Mississippian Mauch Chunk Formation (Pennsylvania), and forms paleokarst on Mississippian Loyalhanna Limestone (Pennsylvania) and Maxville Limestone (Ohio). Strata associated with these unconformities contain several reports of uranium. Unconformities unfavorable for uranium concentration occur beneath the Middle Ordovician (New York), Middle Devonian (Ohio and New York), and Upper Devonian (Ohio and New York); these involve marine strata overlying marine strata and probably much submarine erosion

Procedure for recovery from an uranium containing concentrate and phosphoric acid, as well as an uranium containing concentrate and phosphoric acid obtained by this procedure

International Nuclear Information System (INIS)

1980-01-01

The phosphate ore is dissolved in sulphuric acid and the formed calcium sulphate is separated from the solution. The uranium is then precipitated by adding ammonium fluoride solution to the remaining phosphoric acid solution. When the phosphate ore is dissolved in sulphuric acid, fluorine gas is liberated and this is then used to produce the ammonium fluoride solution. (Th.P.)

Highland Uranium Solution Mining Project. Draft environmental statement

International Nuclear Information System (INIS)

1978-05-01

Exxon Minerals Co. proposes to conduct production-scale solution mining (in situ leaching) of uranium within the existing Highland Operation area in Converse County, Wyoming. The project would result in the temporary removal of 200 acres from grazing and the actual disturbance of 50 acres. About 4500 acre-ft of water will be withdrawn from the ore zone aquifer over the 10-year life of the project. There will be no discharge of liquid effluents from the project; atmospheric effluents will be within acceptable limits. Radiation doses at the nearest ranch resulting from solution mining activities were estimated. The project proposes the production and utilization of 1 to 3 million lb of uranium resources. It will not produce any significant socioeconomic impact on the local area. Alternatives to the project were considered, and conditions for issuing the source material license are listed

On the anomalous concentrations of uranium in sediments from hydrothermal mounds. A geochemical roll-type mechanism

International Nuclear Information System (INIS)

Bernat, M.; Benhassaine, A.

1987-01-01

Sediments close to the nontronite formations of hydrothermal mounds often show anomalously high concentrations of uranium. This is frequently interpreted as being due to seeping of low temperature U bearing hydrothermal water through the basal basalt and into the overlying sediments. But we think that this phenomenon is the consequence of leaching of the sediment by hydrothermal water initially depleted in uranium. The migration of U is favoured by the pH of these water which dissolve the iron oxides and hydroxides giving Fe +++ ions in solution. The location and strength of the formed U anomalies are controlled by geochemical and hydrodynamicals factors. 22 refs [fr

Biological adsorbent for water decontamination from uranium

Energy Technology Data Exchange (ETDEWEB)

Jilek, R [Vyzkumny Ustav Veterinarniho Lekarstvi, Brno-Medlanky (Czechoslovakia); Fuska, J; Nemec, P [Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia). Chemickotechnologicka Fakulta

1978-01-01

A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10/sup -4/ M/dm/sup 3/. Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution.

Biological adsorbent for water decontamination from uranium

International Nuclear Information System (INIS)

Jilek, R.; Fuska, J.; Nemec, P.

1978-01-01

A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10 -4 M/dm 3 . Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution. (author)

Measurements of natural uranium concentration in Caspian Sea and Persian Gulf water by laser fluorimetric method

International Nuclear Information System (INIS)

Garshasbi, H.; Karimi Diba, J.; Jahanbakhshian, M. H.; Asghari, S. K.; Heravi, G. H.

2005-01-01

Natural uranium exists in earth crust and seawater. The concentration of uranium might increase by human manipulation or geological changes. The aim of this study was to verify susceptibility of laser fluorimetry method to determine the uranium concentration in Caspian Sea and Persian Gulf water. Materials and Methods: Laser fluorimetric method was used to determine the uranium concentration in several samples prepared from Caspian Sea and Persian Gulf water. Biological and chemical substances were eliminated in samples for better evaluation of the method. Results: As the concentration of natural uranium in samples increases, the response of instrument (uranium analyzer) increases accordingly. The standard deviation also increased slightly and gradually. Conclusion: Results indicate that the laser fluorimetry method show a reliable and accurate response with uranium concentration up to 100 μg/L in samples after removal of biological and organic substances

Uranium mineralization by ground water in sedimentary rocks, Japan

International Nuclear Information System (INIS)

Doi, K.; Hirono, S.; Sakamaki, Y.

1975-01-01

To solve the mechanism of uranium concentration in stratabound uranium deposits occurring in the basal part of Neogene sediments overlying granite basement, attention was paid to uranium leaching from weathered granite by circulating carbonated fissure waters, to effective adsorbents for fixing uranium from uraniferous ground waters, to structural features controlling the ground-water circulation, and other relevant factors. The evidence for uranium transportation by hydothermal solutions, including hot spring waters, is hard to observe. Conclusions are summarized as follows: Uranium in the deposits is supplied from surrounding source rocks, mostly from granite. Uranium is transported by circulating ground-water solutions. The uranium dissolved in ground water is fixed in minerals in various ways, the most important being adsorption by carbonaceous matter. Ore-grade uranium concentrated from very dilute solutions occurs by multiple repetition of a leaching-and-fixation cycle between minerals or adsorbents and circulating uraniferous ground water. Important factors for uranium mineralization are sufficient uranium, supplied mostly from granite, the existence of effective adsorbents such as carbonaceous matter in the host rocks, and favorable geological, geochemical, and geophysical environments. The last seem to require not only physical and chemical conditions but also correct flow and volume of ground water. (U.S.)

Study of an X-ray fluorescence thin film method for the determination of uranium in low activity solutions

International Nuclear Information System (INIS)

Diaz-Guerra, J. P.

1980-01-01

The application of the X-ray fluorescence thin film technique to the uranium determination in nitric solutions for a concentration range from 1 g/l to 100 g/l and activity levels under 5 mCi/ml is studied. The most suited excitation and measurement conditions are also studied and the uranium matrix effect correction, which is performed through the double dilution, α U U interaction coefficient calculation and internal standard methods, is discussed. The specimen preparation is satisfactorily accomplished by using P.V.C. filters fixed on aluminium supports. (Author) 18 refs

On the peculiarities of subsurface uranium concentrations in the arid regions

International Nuclear Information System (INIS)

Kochenov, A.V.; Chernikov, A.A.

1976-01-01

The general features of uranium distribution in the zone of hypergenesis of the area under investigation suggest a lack of accumulations due to climatic or landscape factors alone and formed at the expense of background near-clark contents of uranium in primary rocks. The low uranium concentrations in the debris layer of weathered crusts of acidic effusive rocks and granites as well as in salt marshes are of areal distribution and, in practice, never recorded as anomalies. The processes of salt formation in the area discussed appear, in the absence of organic matter in the sediments, to be insufficient by themselves for the accumulation of uranium from its near-clark contents in the primary rocks. At the same time the arid conditions are undoubtedly favorable for the formation and persistence of accumulative diffusion aureoles emphasizing and revealing on the surface the smallest and poorest primary concentrations of uranium. It is inadmissible to extrapolate the results of a study of one area to the entire variety of geomorphological conditions of the arid zone. The data reported show that care should be taken in interpreting uranium anomalies in arid areas, by all means taking account of the geological structure of the particular anomalous area and the uranium resources of the primary rocks

Effect of soil parameters on uranium availability to ryegrass

International Nuclear Information System (INIS)

Vandenhove, H.; Van Hees, M.; Wannijn, J.; Wang, L.

2004-01-01

When wishing to assess the impact of radioactive contamination on biota or on an ecosystem, knowledge on the physico-chemical conditions governing the radionuclide availability and speciation in the exposure medium and hence its bioavailability and incorporation is indispensable. The present study explores the dominant soil factors (18 soils collected under pasture) ruling uranium mobility and availability to ryegrass and intents to define and assess the extent of the effect. The soils were selected such that they covered a wide range for those parameters hypothesized as being potentially important in determining U-availability (pH, clay content, Fe and Al oxide and hydroxide content, CaCO 3 , organic carbon). Statistical analysis showed that there were no single soil parameters significantly explaining the uranium concentration in the soil solution, nor the uranium concentration in the plants. Soil pH and iron-oxi-hydroxides explained for 60 % the uranium concentration found in the soil solution (which varied with factor 100). Plant U-concentration was mostly affected by the concentration of U in the soil solution, pH and total inorganic carbon content (R 2 =0.71). Observed U-uptake was highest when pH was below 5.3 or around 7 or higher. The next step was to assess the uranium speciation in the soil solution with a Geochemical Speciation Model. Uranium speciation was found important in explaining the U-uptake observed: apparently, uranyl, UO 2 CO 3 -2 and (UO 2 ) 2 CO 3 (OH) 3 - were the U-species being preferentially transported. (author)

Organic matter in uranium concentration during ancient bed oxidation of carboniferons sediments

International Nuclear Information System (INIS)

Kruglova, V.G.; Uspenskij, V.A.; Dement'ev, P.K.; Kochenov, A.V.

1984-01-01

Changes in the organic matter accompanying the process of epigenetic ore formation are studied using the example of a deposit localized in carboniferous molasse strata of the Cretaceous period. Peculiarities of the organic matter as the main mineralization agent are studied by a complex of physical and themical methods. A distinct relationship between the uranium concentration and the degree of organic matter oxigenation is a most characteristic feature of the ore localization, however, there is no direct correlation between the contents of uranium and organic matter in ores. Uranium minerallzation was accumulated during infiltration of acid uraniferous.waters into grey stratum in the process of the bed oxidation zone formation oxidizing. Brown coal matter possessing a maximum adsorbability, as compared to other sedimentary rocks, apprared to be the uranium precipitator. The adsorption was accompanie by the formation of proper uranium minerals (coffinite, pitchblende) due to uranium reduction by oxidizing organic matter. Thus, the oxidative epigenesis was an are-forming process with the uranium concentration on organic matter proportionally to oxidation of the latter

Non-destructive assay system for uranium and plutonium in reprocessing input solutions. Hybrid K-edge/XRF Densitometer. JASPAS JC-11 final report

International Nuclear Information System (INIS)

Surugaya, N.; Abe, K.; Kurosawa, A.; Ikeda, H.; Kuno, Y.

1997-05-01

As a part of JASPAS programme, a non-radioactive assay system for the accountability of uranium and plutonium in input dissolver solutions of a spent fuel reprocessing plant, called Hybrid K-edge/XRF Densitometer, has been developed at the Tokai Reprocessing plant (TRP) since 1991. The instrument is the one of the hybrid type combined K-edge densitometry (KED) and X-ray fluorescence (XRF) analysis. The KED is used to determine the uranium concentration and the XRF is used to determine the U/Pu ratio. These results give the plutonium concentration in consequence. It is considered that the instrument has the capability of timely on-site verification for input accountancy. The instrument had been installed in the analytical hot cell at the TRP and the experiments comparing with Isotope Dilution Mass Spectrometry (IDMS) method have been carried out. As the results of measurements for the actual input solutions in the acceptance and performance tests, it was typically confirmed that the precision for determining uranium concentration by the KED was within 0.2%, whereas the XRF for plutonium performed within 0.7%. This final report summarizes the design information and performance data so as to end the JASPAS programme. (author)

Calculation of depleted uranium concentration in dental fillings samples using the nuclear track detector CR-39

International Nuclear Information System (INIS)

Mahdi, K. H.; Subhi, A. T.; Tawfiq, N. F.

2012-12-01

The purpose of this study is to determine the concentration of depleted uranium in dental fillings samples, which were obtained some hospital and dental office, sale of materials deployed in Iraq. 8 samples were examined from two different fillings and lead-filling (amalgam) and composite filling (plastic). concentrations of depleted uranium were determined in these samples using a nuclear track detector CR-39 through the recording of the tracks left by of fragments of fission resulting from the reaction 2 38U (n, f). The samples are bombarded by neutrons emitted from the neutron source (2 41A m-Be) with flux of ( 10 5 n. cm- 2. s -1 ). The period of etching to show the track of fission fragments is 5 hours using NaOH solution with normalization (6.25N), and temperature (60 o C ). Concentration of depleted uranium were calculated by comparison with standard samples. The result that obtained showed that the value of the weighted average for concentration of uranium in the samples fillings (5.54± 1.05) ppm lead to thr filling (amalgam) and (5.33±0.6) ppm of the filling composite (plastic). The hazard- index, the absorbed dose and the effective dose for these concentration were determined. The obtained results of the effective dose for each of the surface of the bone and skin (as the areas most affected by this compensation industrial) is (0.56 mSv / y) for the batting lead (amalgam) and (0.54 mSv / y) for the filling composite (plastic). From the results of study it was that the highest rate is the effective dose to a specimen amalgam filling (0.68 mSv / y) which is less than the allowable limit for exposure of the general people set the World Health Organization (WHO), a (1 mSv / y). (Author)

Effects of solution pH and complexing reagents on uranium and thorium desorption under saturated equilibrium conditions

International Nuclear Information System (INIS)

Wang, Yug-Yea; Yu, C.

1992-01-01

Three contaminated bulk surface soils were used for investigating the effect of solution pH and complexing reagents on uranium and thorium desorption. At a low solution pH, the major chemical species of uranium and thorium, uranyl UO 2 +2 , thorium dihydroxide Th(OH) 2 +2 , and thorium hydroxide Th(OH) +3 , tend to form complexes with acetates in the solution phase, which increases the fractions of uranium and thorium desorbed into this phase. At a high solution pH, important uranium and thorium species such as uranyl tricarbonate complex UO 2 (CO) 33 -4 and thorium tetrahydroxide complex Th(OH) 4 tend to resist complexation with acetates. The presence of complexing reagents in solution can release radionuclides such as uranium and/or thorium from the soil to the solution by forming soluble complexes. Sodium bicarbonate (NaHCO 3 ) and diethylenetriaminepentaacetic acid (DTPA) are strong complex formers that released 38% to 62% of total uranium activity and 78% to 86% of total thorium activity, respectively, from the soil samples investigated. Solutions of 0.1 molar sodium nitrate (NaNO 3 ) and 0.1 molar sodium sulfate (Na 2 SO 4 ) were not effective complex formers with uranium and thorium under the experimental conditions. Fractions of uranium and thorium desorbed by 0.15g/200ml humic acid ranged from 4.62% to 6.17% and 1.59% to 7.09%, respectively. This work demonstrates the importance of a knowledge of solution chemistry in investigating the desorption of radionuclides

Ivestigation of uranium adsorption by using coconut shell

International Nuclear Information System (INIS)

Aslani, M.A.A.; Akyil, S.; Aytas, S.; Eral, M.

2001-01-01

At the present study, we investigated the basic features of uranium uptake from dilute aqueous solution by using coconut shell and the effect of uranium on this adsorption phenomena. It has also been shown that the adsorption of uranium was affected with some factors such as pH, uranium concentration, and contact time

Polarographic behaviour of uranium (VI) in tributyl phosphate organic solutions

International Nuclear Information System (INIS)

Degueldre, C.A.; Meklati, M.

1984-01-01

U(VI) determination by D.C. and differential pulse polarography was studied in the organic solutions derived from tributyl phosphate - diluent extracts (after separation from nitric acid media) along with a selected aprotic solvent (i.e.: propylene carbonate and N,N-dimethylacetamide). Miscibility of the TBP-diluent (e.g. cyclohexane, n-hexane, kerosene, n-dodecane) phase with nitric acid as supporting electrolyte, either by addition or already present in the extract was larger in DMA than in PC. In the DMA organic mixture, U(VI) exhibited a DPP peak due to a one electron step, with Esub(p)=-0.4 V (position connected with H 2 O and HNO 3 concentrations). This peak which was proportionnel to the U(VI) concentration from 5x10 -6 to 10 -3 M can be used to determinate directly hexavalent uranium in the industrial organic extraction phases TBP-diluent. (orig.)

Investigation of the uranium-molybdenum diffusion in body centered {gamma} solid solutions; Etude de la diffusion uranium-molybdene dans la solution solide {gamma} cubique centree

Energy Technology Data Exchange (ETDEWEB)

Adda, Y; Mairy, C; Bouchet, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Philibert, J [IRSID, 78 - Saint-Germain-en-Laye (France)

1958-07-01

The body centered {gamma} phase uranium-molybdenum intermetallic diffusion has been studied by different technical methods: micrography, electronic microanalyser, microhardness. The values of several numbers of penetration coefficients are given, and their physical significations has been discussed. The diffusion coefficients, the frequency factor and activation energies has been determined for each concentration. After determination of the Kirkendall effect in this system, we calculated the intrinsic diffusion coefficient of uranium and molybdenum. (author) [French] La dilution intermetallique uranium-molybdene, en phase {gamma} cubique centree, a ete etudiee au moyen de differentes techniques: micrographie, microsonde electronique, microdurete. Les valeurs d'un certain nombre de coefficients de penetration sont donnees et leur signification physique discutee. Les coefficients de diffusion, les facteurs de frequence et les energies d'activation ont ete determines pour chaque concentration. Apres avoir mis en evidence un effet Kirkendall dans ce systeme, on a calcule les coefficients de diffusion intrinseques de l'uranium et du molybdene. (auteur)

Spectrophotometric determination of uranium and plutonium in nitric acid solutions at their co-presence

International Nuclear Information System (INIS)

Levakov, B.I.; Mishenev, V.B.; Nezgovorov, N.Yu.; Ryazanova, G.K.; Timofeev, G.A.

1986-01-01

The method of spectrophotometric determination of uranium (6) and plutonium (4) in nitric acid solutions is described. Uranium is determined by light absorption of the complex with arsenazo 3 in 0.05 mol/l nitric acid at λ=654 nm, plutonium - by light absorption of the complex with xylenol orange in 0.1 mol/l nitric acid at λ=540 nm. To disguise plutonium, tetravalent and certain trivalent elements DTPA is introduced into photometered solution for uranium determination. The relative root-mean square deviation of determination results does not exceed 0.03 in uranium concenration ranges 0.5-5 μg/ml, of plutonium -1-3 μg/ml

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Adsorption of uranium from aqueous solution by PAMAM dendron functionalized styrene divinylbenzene

Energy Technology Data Exchange (ETDEWEB)

Ilaiyaraja, P., E-mail: chemila07@gmail.com [Radiological Safety Division, Radiological Safety and Environmental Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Singha Deb, Ashish Kumar; Sivasubramanian, K. [Radiological Safety Division, Radiological Safety and Environmental Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Ponraju, D. [Safety Engineering Division, Reactor Design Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Venkatraman, B. [Radiological Safety Division, Radiological Safety and Environmental Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India)

2013-04-15

Highlights: ► A new chelating resin PAMAMG{sub 3} -SDB has been synthesized for uranium adsorption. ► The maximum adsorption capacity was determined to be 130.25 mg g{sup −1} at pH 5.5. ► Adsorption capacity increases linearly with increasing dendron generation. ► The adsorbed uranium shall be easily desorbed by simply adjusting the pH < 3. ► Quantitative adsorption of uranium was observed even at high ionic strength. -- Abstract: A new polymeric chelating resin was prepared by growing third generation poly(amido)amine (PAMAMG{sub 3}) dendron on the surface of styrene divinylbenzene (SDB) and characterized by FTIR, TGA and SEM. The ideal branching of dendron in the chelating resin was determined from potentiometric titration. Adsorption of uranium (VI) from aqueous solution using PAMAMG{sub 3}-SDB chelating resin was studied in a series of batch experiments. Effect of contact time, pH, ionic strength, adsorbent dose, initial U(VI) concentration, dendron generation and temperature on adsorption of U(VI) were investigated. Kinetic experiments showed that U(VI) adsorption on PAMAMG{sub 3}-SDB followed pseudo-second-order kinetics model appropriately and equilibrium data agreed well with the Langmuir isotherm model. Thermodynamic parameters (ΔH°, ΔS°, ΔG°) were evaluated from temperature dependent adsorption data and the uranium adsorption on PAMAMG{sub 3}-SDB was found to be endothermic and spontaneous in nature. The sticking probability value (5.303 × 10{sup −9}), kinetic and isotherm data reveal the chemisorption of uranium on PAMAMG{sub 3}-SDB and adsorption capacity of the chelating resin was estimated to be 130.25 mg g{sup −1} at 298 K. About 99% of adsorbed U(VI) can be desorbed from PAMAMG{sub 3}-SDB by a simple acid treatment suggesting that the chelating resin is reusable.

Uranium concentrations in the phosphates of Congo related to marin and continental mineral authigenesis

International Nuclear Information System (INIS)

Giresse, P.; N'Landou, J. de Dieu; Wiber, M.

1984-01-01

In the Maastrichtian phosphates of Tchivoula (Congo), uanium, for the most part fixed and tetravalent in marine apatites in there after mobilized and occasionally concentrates during the course of successive stages of dissolution, recrystallization (secondary apatite) or authigenesis (ferro-aluminous phosphates, autunite and torbernite). Very high levels near the top of the deposit appear to be related to the percolation of uraniferous solutions from Ypresian phosphatic beds which are no longer present. In the marine Tertiary phosphates of Djeno, diagenesis is less advanced; radial changes in uranium concentration on the scale of individual coprolites of selacians can be observed and are related to the loss of P 2 O 5 [fr

Chemical aspects of the precise and accurate determination of uranium and plutonium from nuclear fuel solutions

International Nuclear Information System (INIS)

Heinonen, O.J.

1981-01-01

A method for the simultaneous or separate determination of uranium and plutonium has been developed. The method is based on the sorption of uranium and plutonium as their chloro complexes on Dowex 1x10 column. When separate uranium and plutonium fractions are desired, plutonium ions are reduced to Pu (III) and eluted, after which the uranium ions are eluted with dilute HCl. Simultaneous stripping of a mass ratio U/Pu approximately 1 fraction for mass spectrometric measurements is achieved by proper choice of eluant HC1 concentration. Special attention was paid to the obtaining of americium free plutonium fractions. The distribution coefficient measurements showed that at 12.5-M HCl at least 30 % of americium ions formed anionic chloro complexes. The chemical aspects of isotopic fractionation in a multiple filament thermal ionization source were also investigated. Samples of uranium were loaded as nitrates, chlorides, and sulphates and the dependence of the measured uranium isotopic ratios on the chemical form of the loading solution as well as on the filament material was studied. Likewise the dependence of the formation of uranium and its oxide ions on various chemical and instrumental conditions was investigated using tungsten and rhenium filaments. Systematic errors arising from the chemical conditions are compared with errors arising from the automatic evaluation of of spectra. (author)

Carbonate heap leach of uranium-contaminated soils

International Nuclear Information System (INIS)

Turney, W.R.; Mason, C.F.V.; Longmire, P.

1994-01-01

A new approach to removal of uranium from soils based on existing heap leach mining technologies proved highly effective for remediation of soils from the Fernald Environmental Management Project (FEMP) near Cincinnati, Ohio. In laboratory tests, remediation of uranium-contaminated soils by heap leaching with carbonate salt solutions was demonstrated in column experiments. An understanding of the chemical processes that occur during carbonate leach of uranium from soils may lead to enhancement of uranium removal. Carbonate leaching requires the use of an integrated and closed circuit process, wherein the leach solutions are recycled and the reagents are reused, resulting in a minimum secondary waste stream. Carbonate salt leach solution has two important roles. Primarily, the formation of highly soluble anionic carbonate uranyl species, including uranyl dicarbonate (UO 2 CO 32 = ) and uranyl tricarbonate (UO 2 CO 33 4- ), allows for high concentration of uranium in a leachate solution. Secondly, carbonate salts are nearly selective for dissolution of uranium from uranium contaminated soils. Other advantages of the carbonate leaching process include (1) the high solubility, (2) the selectivity, (3) the purity of the solution produced, (4) the relative ease with which a uranium product can be precipitated directly from the leachate solution, and (5) the relatively non-corrosive and safe handling characteristics of carbonate solutions. Experiments conducted in the laboratory have demonstrated the effectiveness of carbonate leach. Efficiencies of uranium removal from the soils have been as high as 92 percent. Higher molar strength carbonate solutions (∼0.5M) proved more effective than lower molar strength solutions (∼ 0.1M). Uranium removal is also a function of lixiviant loading rate. Furthermore, agglomeration of the soils with cement resulted in less effective uranium removal

Adsorptivity of uranium by aluminium-activated carbon composite adsorbent

International Nuclear Information System (INIS)

Katoh, Shunsaku; Sugasaka, Kazuhiko; Fujii, Ayako; Takagi, Norio; Miyai, Yoshitaka

1976-01-01

To research the adsorption process of uranium from sea water by aluminium-activated carbon composite adsorbent (C-Al-OH), the authors examined the effects of temperature, pH and carbonate ion concentration of the solution upon the adsorption of uranium, using sodium chloride solution and natural sea water. The continued mixing of the solution for the duration of two to four hours was required to attain the apparent equilibrium of adsorption. The adsorption velocity at an early stage and the uptake of uranium at the final stage showed an increase in proportion to a rise in the adsorption temperature. In the experiment of adsorption for which sodium chloride solution was used, the linear relationship between the logarithm of the distribution coefficient (K sub(d)) and the pH of the solution was recognized. The uptake of the uranium from the solution at the pH of 12 increased as the carbonate ion concentration in the solution decreased. The uranyl ion in the natural sea water was assumed to be uranyl carbonate complex ion (UO 2 (CO 3 ) 3 4- ). As the result of the calculation conducted by using the formation constants for uranyl complexes in literature, it was found that uranyl hydroxo complex ion (UO 2 (OH) 3 - ) increased in line with a decrease of the carbonate ion concentration in the solution. The above results of the experiment suggested that the adsorption of uranium by the adsorbent (C-Al-OH) was cationic adsorption or hydrolysis adsorption being related with the active proton on the surface of the adsorbent. (auth.)

Preparation of uranium-based oxide catalysts; Preparation de catalyseurs oxydes a base d'uranium

Energy Technology Data Exchange (ETDEWEB)

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

1965-07-01

We have studied the thermal decomposition of uranyl and uranium IV oxalates as a mean of producing uranium dioxide. We have isolated the main intermediate phases of the decompositions and have indexed the lines of their X-ray diffraction patterns. The oxides produced by the decomposition are ill-defined and unstable: they strongly absorb atmospheric oxygen with modification of the composition and, in certain cases, of the structure (pyrophoric oxide). With a view to obtaining stable oxides, we have prepared mixed uranium-thorium oxalates. In order to prepare an oxalate having a homogeneous composition, it is necessary to adopt a well-defined preparation method: the addition of solutions of thorium and uranium IV nitrates to a continually saturated oxalic acid solution. The mixed oxide obtained from the thermal decomposition of an oxalate U{sub x}Th{sub 1-x}(C{sub 2}O{sub 4}){sub 2}, 2 H{sub 2}O at 500 C for 24 hours in a current of oxygen leads to a cubic structure which is well-defined both in the bulk and superficially when x is less than 0.35. Above this atomic concentration of uranium, some uranium moves out of the lattice in the form of UO{sub 3} or U{sub 3}O{sub 8} according to the temperature. The mixed oxide is not stoichiometric,(U{sub x}Th{sub 1-x}O{sub 2+y}) and the average degree of oxidation of the uranium varies with the temperature and partial oxygen pressure. The oxides thus formed have a high surface area. By dissolving the mixed oxalates in a concentrated solution of ammonium oxalate, it is possible to deposit the catalyst on a support, but the differences in the solubilities of the thorium and uranium IV oxalates in the ammonium oxalate make it impossible to prepare double salts formed either of thorium and uranium and of ammonium. (author) [French] Nous avons etudie la decomposition thermique des oxalates d'uranyle et d'uranium IV en vue d'aboutir au dioxide d'uranium. Nous avons pu isoler les principales phases intermediaires des decompositions

Leaching of uranium from Syrian phosphorite (sodium carbonate-bicarbonate)

International Nuclear Information System (INIS)

Abou-Jamous, J.Kh.

1991-01-01

The leaching of uranium from Syrian phosphorite by sodium carbonate-bicarbonate solution has been studied, using a batch technique. Parameters influencing percentage extraction of uranium that are considered and studies in this work are: Leachant concentration, particle size, heat treatment, leachant renewal, phosphorite renewal and contact time. All measurements of uranium from aqueous solutions were carried out by fluorometry. (author). 12 refs., 4 figs., 1 tab

Uranium hydrogeochemical and stream sediment reconnaissance of the Newcastle NTMS Quadrangle, Wyoming, including concentrations of forty-two additional elements

International Nuclear Information System (INIS)

Goff, S.J.; Sandoval, W.F.; Gallimore, D.L.; Talcott, C.L.; Martinez, R.G.; Minor, M.E.; Mills, C.F.

1980-06-01

Water and sediment samples were collected and each water sample was analyzed for U, and each sediment sample was analyzed for 43 elements, including U and Th. Uranium concentrations in water samples range from below the detection limit of 0.02 ppB to 702.26 ppB and have a median of 1.73 ppB and a mean of 11.76 ppB. Water samples containing high uranium concentrations generally are associated with known uranium mining activity or units known to be uranium bearing. About one-third of the water samples containing high uranium concentrations were collected from locations within the Pumpkin Buttes and Turnercrest-Ross Districts. Nearly half of the water samples containing high uranium concentrations were collected from locations just west of the Monument Hill and Highland Flats-Box Creek Districts. Similar anomalous uranium concentrations in this region have been reported updip from Exxon's Highland uranium deposits. High uranium concentrations were also found associated with the Lance Creek-Old Woman Anticline District. Uranium concentrations in sediment samples range from 1.14 to 220.70 ppM and have a median of 3.37 ppM and a mean of 4.03 ppM. Throughout the major uranium mining districts of the Powder River Basin, sediment samples with high uranium concentrations were collected from dry streams located near wells producing water samples with high uranium concentrations. High uranium concentrations were also found associated with the Lance Creek oil field where uranium mineralization is known in the White River formation. High uranium concentrations were also found in sediment samples in areas where uranium mineralization is not known. These samples are from dry streams in areas underlain by the White River formation, the Niobrara formation, and the Pierre, Carlisle, Belle Fourche, and Mowry shales

Adsorption kinetic investigations of low concentrated uranium in aqua media by polymeric adsorban

International Nuclear Information System (INIS)

Guerellier, R.

2004-02-01

In order to remove the uranium from aqueous media, the solution of polyethylene glycol in acrylonitrile was irradiated using ''6' degree Celsius Co γ-ray source and Interpenetrating Polymer Networks (IPNs) was formed. After IPNs were amidoximated at 65 0 for 3.5 hours, they were kept in 10''-''2 M of uranil nitrate solution at 17, 25, 35, 45 degree Celsius temperatures until to establish the adsorption equilibrium. Adsorption analyses were measured by gamma spectrometer, gravimetry and UV spectrofotometer. Structure analysis of IPN, before and after amidoximation and after the adsorption of uranium, was interpreted by FTIR spectrometer. It was found that as the temperature increased the amount of max adsorption also increased. The amount of max adsorption capacity at 45 degree Celsius was 602 mg U/g IPN. In addition to, it was determined that the uranium adsorption increased a little in shaking media. The reaction was determined as 'zeroth degree' until 240 minutes due to the changing of adsorption capacity by the time at different temperatures. It was observed that as the temperature increased, the adsorption rate also increased and the activation energy was calculated as 34.6 kJ/mol. By using the changing of adsorption equilibrium coefficient by the temperature, thermodynamic quantities of ΔH, ΔS and ΔG were calculated consecutively. Adsorption reaction was determined as endothermic and it was interpreted that the adsorption was controlled by particular diffusion, namely it was a physical adsorption. Adsorption isotherms were found by changing the solution concentrations from 5X10''4 to parallel x parallel O''- 2 M at 20, 25, 35, 45 degree Celsius temperatures. The obtained data from this study was applied to different adsorption isotherms. It was observed that at lower temperatures, the adsorption isotherms were fitted to Giles C type, at higher temperatures, they were fitted to Freundlich type

Assessment of trace ground-water contaminants release from south Texas in-situ uranium solution-mining sites

Energy Technology Data Exchange (ETDEWEB)

Kidwell, J.R.; Humenick, M.J.

1981-01-01

The future of uranium solution mining in south Texas depends heavily on the industry's ability to restore production zone ground water to acceptable standards. This study investigated the extent of trace contaminant solubilization during mining and subsequent restoration attempts, first through a literature search centered on uranium control mechanisms, and then by laboratory experiments simulating the mining process. The literature search indicated the complexity of the situation. The number of possible interactions between indigenous elements and materials pointed on the site specificity of the problem. The column studies evaluated three different production area ores. Uranium, molybdenum, arsenic, vanadium, and selenium were analyzed in column effluents. After simulated mining operations were completed, uranium was found to be the most persistent trace element. However, subsequent ground water flushing of the columns could restore in-situ water to EPA recommended drinking water concentrations. Limited data indicated that ground water flowing through mined areas may solubilize molybdenum present in down gradient areas adjacent to the production zone due to increased oxidation potential of ground water if adequate restoration procedures are not followed.

Radiation-induced defects in clay minerals, markers of the mobility of the uranium in solution in the unconformity-type uranium deposits

International Nuclear Information System (INIS)

Morichon, E.

2008-10-01

This study presents the works driven on three groups of clay minerals (kaolins, illite, sudoite (di-tri-octahedral chlorites)) characteristics of the alteration halos surrounding unconformity-type uranium deposits, in order to reveal uranium paleo-circulations in the intra-cratonic meso-Proterozoic basins (1,2 - 1,6 Ga). Thanks to Electron Paramagnetic Resonance Spectroscopy (EPR), we were able to highlight the persistence of structural defects in kaolin-group minerals contemporaneous of the basin diagenesis, and demonstrate the existence of relatively stable defects in illites and sudoites contemporaneous of the uranium deposits setting. Thus, the main defect in illite (Ai centre) and the main defect in sudoite (As centre) are characterized by their g components such as, respectively, gt = 2,003 et g// = 2,051 for illite and gt = 2,008 et g// = 2,051 for sudoite. As the main defect in kaolins (kaolinite/dickite), the main defects in illite and sudoite are perpendicularly oriented according to the (ab) plane, on the tetrahedral Si-O bound. However, their thermal stabilities seem different. The observation of samples from different zones (background, anomal or mineralized) of the Athabasca basin (Canada) allowed to identify a parallel evolution between actual defects concentration measured in the different clay minerals and the proximity of the mineralisation zones. Consequently, clays minerals can be considered as potential plotters of zones where uranium-rich solutions have circulated. (author)

Recovery of uranium in the production of concentrated phosphoric acid by a hemihydrate process

International Nuclear Information System (INIS)

Nakajima, S.; Miyamoto, M.

1983-01-01

Nissan Chemical Industries as manufacturers of phosphoric acid have studied the recovery of uranium, based on a concentrated phosphoric acid production process. The process consists of two stages, a hemihydrate stage with a formation of hemihydrate and a filtration section, followed by a dihydrate stage with hydration and a filtration section. In the hemihydrate stage, phosphate is treated with a mixture of phosphoric acid and sulphuric acid to produce phosphoric acid and hydrous calcium sulphate; the product is recovered in the filtration section and its concentration is 40-50% P 2 O 3 . In the dihydrate stage, the hemihydrate is transformed by re-dissolution and hydration, producing hydrous calcium sulphate, i.e. gypsum. This process therefore comprises two parts, each with different acid concentrations. As the extraction of uranium is easier in the case of a low concentration of phosphoric acid, the process consists of the recovery of uranium starting from the filtrate of the hydration section. The tests have shown that the yield of recovery of uranium was of the order of 80% disregarding the handling losses and no disadvantageous effect has been found in the combination of the process of uranium extraction with the process of concentrated phosphoric acid production. Compared with the classical process where uranium is recovered from acid with 30% P 2 O 5 , the process of producing high-concentration phosphoric acid such as the Nissan process, in which the uranium recovery is effected from acid with 15% P 2 O 5 from the hydration section, presents many advantages [fr

Nuclear fuel technology - Determination of uranium in solutions, uranium hexafluoride and solids - Part 2: Iron(II) reduction/cerium(IV) oxidation titrimetric method

International Nuclear Information System (INIS)

2004-01-01

This first edition of ISO 7097-1 together with ISO 7097-2:2004 cancels and replaces ISO 7097:1983, which has been technically revised, and ISO 9989:1996. ISO 7097 consists of the following parts, under the general title Nuclear fuel technology - Determination of uranium in solutions, uranium hexafluoride and solids: Part 1: Iron(II) reduction/potassium dichromate oxidation titrimetric method; Part 2: Iron(II) reduction/cerium(IV) oxidation titrimetric method. This part 2. of ISO 7097 describes procedures for determination of uranium in solutions, uranium hexafluoride and solids. The procedures described in the two independent parts of this International Standard are similar: this part uses a titration with cerium(IV) and ISO 7097-1 uses a titration with potassium dichromate

Nuclear fuel technology - Determination of uranium in solutions, uranium hexafluoride and solids - Part 1: Iron(II) reduction/potassium dichromate oxidation titrimetric method

International Nuclear Information System (INIS)

2004-01-01

This first edition of ISO 7097-1 together with ISO 7097-2:2004 cancels and replaces ISO 7097:1983, which has been technically revised, and ISO 9989:1996. ISO 7097 consists of the following parts, under the general title Nuclear fuel technology - Determination of uranium in solutions, uranium hexafluoride and solids: Part 1: Iron(II) reduction/potassium dichromate oxidation titrimetric method; Part 2: Iron(II) reduction/cerium(IV) oxidation titrimetric method. This part 1. of ISO 7097 describes procedures for the determination of uranium in solutions, uranium hexafluoride and solids. The procedures described in the two independent parts of this International Standard are similar: this part uses a titration with potassium dichromate and ISO 7097-2 uses a titration with cerium(IV)

Behaviour of the pH adjustment, Ion exchange and concentrate precipitation stages in the acid leaching of uranium phosphate ores; Tratamiento de disoluciones de lixiviacion de minerales de uranio en presencia de fosfatos. Comportamiento en las etapas de ajuste de PH, cambio de ion y precipitacion de concentrados

Energy Technology Data Exchange (ETDEWEB)

Estrada Aguilar, J; Uriarte Hueda, A

1962-07-01

The uranium recovery from acid leach solutions of uranium-phosphate ores has been studied. Relations have been found between the solution characteristics and the results obtained at different stages of the process. The following data can thus be predicted: solids to remove and uranium recovery in the pH adjustment stage, uranium capacity of the resin, more suitable eluating agent, elution velocity and uranium concentration in the eluate in the ion exchange stage, and composition of the concentrate produced by direct precipitation of the eluate in the concentrate precipitation stage. (Author) 8 refs.

Uranium adsorption by non-treated and chemically modified cactus fibres in aqueous solutions

International Nuclear Information System (INIS)

Melpomeni Prodromou; Ioannis Pashalidis

2013-01-01

The adsorption efficiency of Opuntia ficus indica fibres regarding the removal of hexavalent uranium [U(VI)] from aqueous solutions has been investigated prior and after the chemical treatment (e.g. phosphorylation and MnO 2 -coating) of the biomass. The separation/removal efficiency has been studied as a function of pH, uranium concentration, adsorbent mass, ionic strength, temperature and contact time. Evaluation of the experimental data shows that biosorption is strongly pH-depended and that the MnO 2 -coated product presents the highest adsorption capacity followed by the phosphorylated and non-treated material. Experiments with varying ionic strength/salinity don't show any significant effect on the adsorption efficiency, indicating the formation of inner-sphere surface complexes. The adsorption reactions are in all cases exothermic and relatively fast, particularly regarding the adsorption on the MnO 2 -coated product. The results of the present study indicate that adsorption of uranium from waters is very effective by cactus fibres and particularly the modified treated fibres. The increased adsorption efficiency of the cactus fibres is attributed to their primary and secondary fibrillar structure, which result in a relative relative high specific surface available for sorption. (author)

Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

International Nuclear Information System (INIS)

Souza, Jose Antonio Batista de

2011-01-01

IPEN-CNEN/SP developed the technology to produce the dispersion type fuel elements for research reactors and made it available for routine production. Today, the fuel produced in IPEN-CNEN/SP is limited to the uranium concentration of 3.0 gU/cm 3 for U 3 Si 2 -Al dispersion-based and 2.3 gU/cm 3 for U 3 O 8 -Al dispersion. The increase of uranium concentration in fuel plates enables the reactivity of the reactor core reactivity to be higher and extends the fuel life. Concerning technology, it is possible to increase the uranium concentration in the fuel meat up to the limit of 4.8 gU/cm 3 in U 3 Si 2 -Al dispersion and 3.2 gU/cm 3 U 3 O 8 -Al dispersion. These dispersions are well qualified worldwide. This work aims to develop the manufacturing process of both fuel meats with high uranium concentrations, by redefining the manufacturing procedures currently adopted in the Nuclear Fuel Center of IPEN-CNEN/SP. Based on the results, it was concluded that to achieve the desired concentration, it is necessary to make some changes in the established procedures, such as in the particle size of the fuel powder and in the feeding process inside the matrix, before briquette pressing. These studies have also shown that the fuel plates, with a high concentration of U 3 Si 2 -Al, met the used specifications. On the other hand, the appearance of the microstructure obtained from U 3 O 8 -Al dispersion fuel plates with 3.2 gU/cm 3 showed to be unsatisfactory, due to the considerably significant porosity observed. The developed fabrication procedure was applied to U 3 Si 2 production at 4.8 gU/cm 3 , with enriched uranium. The produced plates were used to assemble the fuel element IEA-228, which was irradiated in order to check its performance in the IEA-R1 reactor at IPEN-CNEN/SP. These new fuels have potential to be used in the new Brazilian Multipurpose Reactor - RMB. (author)

Study of algae's adsorption to uranium ion in water solution

International Nuclear Information System (INIS)

Du Yang; Qiu Yongmei; Dan Guiping; Zhang Dong; Lei Jiarong

2007-01-01

The adsorption efficiencies of the algae to uranium ion were determined at various pH, uranium ion concentrations, adsorption temperatures and the species of coexisted metal ions, and the effect of coexisted metal ion on the adsorption efficiency was researched. The experimental results at pH= 5-8 are as follows. 1) the adsorption capacity is a constant to be about 1.40 μg/g for the Yantai red alga and the sea spinach, and is changeable in the range of 1.03-2.23 μg/g with pH for the sea edible fungus; 2) for the algae the adsorption efficiency and adsorption capacity are related to uranium ion concentration, and the maximum adsorption efficiency and capacity is 95.8% and 65.4 μg/g, respectively; 3) the adsorption process for 24 h is not dependent on the temperature; 4) the effect of the species of coexisted metal ions on the adsorption capacity of uranium ion is various with the time during adsorption process. (authors)

Selective separation of iron from uranium in quantitative determination of traces of uranium by alpha spectrometry in soil/sediment sample.

Science.gov (United States)

Singhal, R K; Narayanan, Usha; Karpe, Rupali; Kumar, Ajay; Ranade, A; Ramachandran, V

2009-04-01

During this work, controlled redox potential methodology was adopted for the complete separation of traces of uranium from the host matrix of mixed hydroxide of Iron. Precipitates of Fe(+2) and Fe(+3) along with other transuranic elements were obtained from acid leached solution of soil by raising the pH to 9 with 14N ammonia solution. The concentration of the uranium observed in the soil samples was 200-600 ppb, whereas in sediment samples, the concentration range was 61-400 ppb.

Transport of uranium by supported liquid membrane containing bis(2-ethylhexyl) hydrogenphosphate and 1-octanol

International Nuclear Information System (INIS)

Akiba, Kenichi; Kanno, Takuji; Takahashi, Toshihiko.

1984-01-01

Carrier-mediated transport of uranium(VI) has been studied by means of liquid membranes impregnated in a microporous polymer. Liquid membranes containing bis(2-ethylhexyl) hydrogenphosphate (DEHPA) alone yielded inadequate stripping of uranium. The addition of 1-octanol to DEHPA solutions resulted in a decrease in extractability, and made it possible to control the distribution ratio of uranium. Uranium in the feed solution was sufficiently transported across the liquid membrane containing this DEHPA-1-octanol mixture into the product solution. The apparent rate constant (ksub(obs)) of transport increased slightly with an increase in carrier concentrations. Variations in acid concentrations of the feed solution (pH 2.5--3.2) and the product solution (0.1--1.0 M H 2 SO 4 ) had little effect on the transport rate. A large excess of uranium, more than the carrier content in the liquid membrane, was finally concentrated in the stripping acid. (author)

Ultrastructural localization of uranium biosorption in Penicillium digitatum by stem x-ray microanalysis

International Nuclear Information System (INIS)

Galun, M.; Galun, E.

1987-01-01

When Penicillium digitatum Saccardo cultures are exposed to aqueous solutions containing soluble uranium salts, considerable amounts of this element are accumulated in the fungal mycelium. The accumulated uranium is retained after thorough rinsing with distilled water but is removed by alkali carbonate solutions. Analysis of thick sections (0.5 μm) of the fungal hyphae with TEM, after incubation in UO 2 Cl 2 solutions of varying concentrations under both light and dark conditions, revealed conspicuous crystal-like deposits in UO 2 Cl 2 -exposed hyphae, but none in the control hyphae. Thick sections were necessary for crystal visualization. Using energy-dispersive X-ray analysis, uranium was detected as the only heavy element in these crystals. Uranium crystal biosorption was localized on the outside surface of the hyphal cell wall (following short exposures to relatively low uranium concentrations) or inside the cell wall (following long exposure to relatively high uranium concentrations). In some cases, crystal-like deposits of uranium salts were located on the outside surface as well as inside the cell. (author)

The effects of different uranium concentrations on soil microbial populations and enzymatic activities

International Nuclear Information System (INIS)

Bagherifam, S.; Lakziyan, A.; Ahmadi, S. J.; Fotovvat, A.; Rahimi, M. F.

2010-01-01

Uranium is an ubiquitous constituent of natural environment with an average concentration of 4 mg/kg in earth crust. However, in local areas it may exceed the normal concentration due to human activities resulting in radionuclide contamination in groundwater and surface soil. The effect of six levels of uranium concentration (0, 50, 100,250. 500 and 1000 mg kg -1 ) on soil phosphatase activities and microbial populations were studied in a completely randomized design as a factorial experiment with three replications. The results showed a significant decrease in phosphatase activity. The result of the experiment suggests that soil microbial populations (bacteria, funji and actinomycetes) decrease by increasing the uranium levels in the soil. Therefore, assessment of soil enzymatic activities and microbial populations can be helpful as a useful index for a better management of uranium and radioactive contaminated soils.

Application of fission track technique for estimation of uranium concentration in drinking waters of Punjab

International Nuclear Information System (INIS)

Prabhu, S.P.; Raj, Sanu S.; Sawant, P.D.; Kumar, Ajay; Sarkar, P.K.; Tripathi, R.M.

2010-01-01

Full text: Drinking water samples were collected from four different districts, namely Bhatinda, Mansa, Faridkot and Firozpur, of Punjab for ascertaining the U(nat.) concentrations. The samples were collected from bore wells, hand pumps, tube wells and treated municipal water supply. All these samples (235 nos.) collected were preserved and processed by following the international standard protocol and analyzed by Laser Fluorimetry. Results of analysis by laser fluorimetry have been already reported. To ensure accuracy of the data obtained by laser fluorimetry, few samples (10 nos) from each district were analyzed by alpha spectrometry as well as by fission track analysis (FTA) technique. FTA in solution media for uranium has been already standardized in Bioassay laboratory of Health Physics Division. Few of drinking water sample was directly transferred to polythene tube sealed at one end. Lexan detector with proper identification mark was immersed in the samples and the other open end of the tube was also heat-sealed. Two tubes containing samples and one containing uranium standard (80 ppb) were irradiated in the Pneumatic Carrier Facility (PCF) of DHRUVA reactor. The Lexan detectors were then chemically etched and tracks were counted under an optical microscope at 400X magnification. Concentration of uranium in sample was determined by comparison technique. Quality assurance was carried out by replicate analysis and by analysis of standard reference materials. Uranium concentration in these samples ranged from 3.2 to 60.5 ppb with an average of 28.8 ppb. A t-test analysis for paired data was done to compare the results obtained by FTA and those obtained by laser fluorimeter. The calculated value for t is -1.19, which is greater than the tabulated value of t for 40 observations (-2.02 at 95% confidence level). This shows that the results of the measurements carried out by the FTA and laser fluorimetry are not significantly different. The preliminary studies

Comparative study of uranium concentration in water samples of SW and NE Punjab, India

International Nuclear Information System (INIS)

Saini, Komal; Bajwa, B.S.

2014-01-01

Since the commencement of the earth, radiations and natural radioactivity has always been a part of environment. Uranium is heaviest naturally occurring element which is widespread in nature, mainly occurs in granites mineral deposits. The natural weathering of rocks such as granite dissolves the natural uranium, which goes into groundwater by leaching and precipitation called illumination process. People are always exposed to certain amount of uranium from air, water, soil and food as it is usually present in these components. About 85% of ingested uranium enter into human body through drinking water which makes it very important to estimate uranium concentration in potable water. Uranium and some other heavy metals may increase the risk of kidney damage, cancer diseases where experimental evidence suggests that respiratory and reproductive system are also affected by uranium exposure. In the present study comparative study of uranium concentration in potable water samples of SW and NE Punjab has been analysed

Process for iron separation from an organic solution containing uranium

International Nuclear Information System (INIS)

Textoris, A.; Lyaudet, G.; Bathelier, A.

1987-01-01

Iron is separated from an organic solution of U and Fe in a phosphine oxide and an acid organic phosphorus compound by reaction on oxalic acid or a mixture of sulfuric and phosphoric acid or phosphoric acid. Uranium stays in the initial organic solution and iron is transferred to the aqueous phase [fr

Effects of uranium concentration on microbial community structure and functional potential.

Science.gov (United States)

Sutcliffe, Brodie; Chariton, Anthony A; Harford, Andrew J; Hose, Grant C; Greenfield, Paul; Elbourne, Liam D H; Oytam, Yalchin; Stephenson, Sarah; Midgley, David J; Paulsen, Ian T

2017-08-01

Located in the Northern Territory of Australia, Ranger uranium mine is directly adjacent to the UNESCO World Heritage listed Kakadu National Park, with rehabilitation targets needed to ensure the site can be incorporated into the park following the mine's closure in 2026. This study aimed to understand the impact of uranium concentration on microbial communities, in order to identify and describe potential breakpoints in microbial ecosystem services. This is the first study to report in situ deployment of uranium-spiked sediments along a concentration gradient (0-4000 mg U kg -1 ), with the study design maximising the advantages of both field surveys and laboratory manipulative studies. Changes to microbial communities were characterised through the use of amplicon and shotgun metagenomic next-generation sequencing. Significant changes to taxonomic and functional community assembly occurred at a concentration of 1500 mg U kg -1 sediment and above. At uranium concentrations of ≥ 1500 mg U kg -1 , genes associated with methanogenic consortia and processes increased in relative abundance, while numerous significant changes were also seen in the relative abundances of genes involved in nitrogen cycling. Such alterations in carbon and nitrogen cycling pathways suggest that taxonomic and functional changes to microbial communities may result in changes in ecosystem processes and resilience. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Development of practical decontamination process for the removal of uranium from gravel.

Science.gov (United States)

Kim, Ilgook; Kim, Gye-Nam; Kim, Seung-Soo; Choi, Jong-Won

2018-01-01

In this study, a practical decontamination process was developed to remove uranium from gravel using a soil washing method. The effects of critical parameters including particle size, H 2 SO 4 concentration, temperature, and reaction time on uranium removal were evaluated. The optimal condition for two-stage washing of gravel was found to be particle size of 1-2 mm, 1.0 M H 2 SO 4 , temperature of 60°C, and reaction time of 3 h, which satisfied the required uranium concentration for self-disposal. Furthermore, most of the extracted uranium was removed from the waste solution by precipitation, implying that the treated solution can be reused as washing solution. These results clearly demonstrated that our proposed process can be indeed a practical technique to decontaminate uranium-polluted gravel.

Application of bacterial leaching technology to deep solution-mining conditions for uranium extraction. Final report, September 1, 1978-September 30, 1981

International Nuclear Information System (INIS)

Brierley, J.A.; Brierley, C.L.; Torma, A.E.

1982-03-01

Microorganisms were evaluated for use in recovery of uranium under conditions of in-situ solution mining. The cultures tested were Thiobacillus ferrooxidans, the faculative-thermophilic TH3 strain, and two Sulfolobus species. Growth of the organisms occurred in the presence of 0.34 to 5.0 mM uranyl ion with higher concentrations being inhibitory. Uranium ore from the Anaconda Minerals Co. Jackpile mine was not readily leachable by microorganisms. To support bacterial activity the ore was supplemented with pyrite or ferrous iron. The ore possessed some toxic properties. T. ferrooxidans was able to assist in leaching of uranium from the ore at a hydrostatic pressure of 10.3 MPa

Uranium ore processing

International Nuclear Information System (INIS)

Ritcey, G.M.; Haque, K.E.; Lucas, B.H.; Skeaff, J.M.

1983-01-01

The authors have developed a complete method of recovering separately uranium, thorium and radium from impure solids such as ores, concentrates, calcines or tailings containing these metals. The technique involves leaching, in at least one stage. The impure solids in finely divided form with an aqueous leachant containing HCl and/or Cl 2 until acceptable amounts of uranium, thorium and radium are dissolved. Uranium is recovered from the solution by solvent extraction and precipitation. Thorium may also be recovered in the same manner. Radium may be recovered by at least one ion exchange, absorption and precipitation. This amount of iron in the solution must be controlled before the acid solution may be recycled for the leaching process. The calcine leached in the first step is prepared in a two stage roast in the presence of both Cl 2 and a metal sulfide. The first stage is at 350-450 0 and the second at 550-700 0

Adaptive control theory of concentration in the uranium enrichment plant

International Nuclear Information System (INIS)

Sugitsue, Noritake; Miyagawa, Hiroshi; Yokoyama, Kaoru; Nakakura, Hiroyuki

1999-01-01

This paper presents the new adaptive control of concentration in the uranium enrichment plant. The purpose of this control system is average concentration control in production tram. As a result the accuracy and practical use of this control system have already been confirmed by the operation of the uranium enrichment demonstration plant. Three elements of technology are required to this method. The first is the measurement of the concentration using product flow quantity change. This technology shall be called 'Qp difference to Xp transform method'. The second is the relationship between temperature change and flow quantity using G.M.D.H. (Groupe Method of Data Handling) and the third is the estimation of temperature change using AR (Auto-regressive) model. (author)

Uranium concentration in building materials used in the central region of Egypt

International Nuclear Information System (INIS)

Higgy, R.H.; El-Tahawy, M.S.; Ghods, A.

1997-01-01

Within a radiological survey of the building materials used in the urban dwellings in the central region of Egypt, the uranium concentration in 80 representative samples of raw and fabricated building materials are determined using laser fluorimetry technique. For 40 samples from the studied raw building materials of sand, gravel, gypsum, lime-stone, granite and marble the determined uranium concentration values range between 0.3 and 3.6 ppm for all these samples except for one type of granite having the corresponding value of 7.8 ppm. For 37 samples from studied fabricated building materials of normal cement, clay brick, sand brick, tiles and ceramic plates the determined uranium concentration values range from 0.5 to 3.4 ppm. The corresponding values for three types of iron cement are 3.1, 6.1 and 9.3 ppm. The radium-226 content (of the uranium-238 series) in the same samples was determined using high resolution gamma-ray spectrometers based on HP Ge-detectors. The data obtained by the two techniques are in good agreement for the majority of the studied samples. (author)

Yellow cake to ceramic uranium dioxide

International Nuclear Information System (INIS)

Zawidzki, T.W.; Itzkovitch, I.J.

1983-01-01

This overview article first reviews the processes for converting uranium ore concentrates to ceramic uranium dioxide at the Port Hope Refinery of Eldorado Resources Limited. In addition, some of the problems, solutions, thoughts and research direction with respect to the production and properties of ceramic UO 2 are described

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

International Nuclear Information System (INIS)

Robertson, R.

1986-01-01

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

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

International Nuclear Information System (INIS)

Weterings, C.A.M.; Janssen, J.A.

1985-01-01

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

Energy Technology Data Exchange (ETDEWEB)

Weterings, C.A.M.; Janssen, J.A.

1985-04-30

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone.

Development of a technique for the on line determination of uranium in solution by gamma ray spectroscopy

International Nuclear Information System (INIS)

Singh, Sarabjit; Ramaswami, A.; Gill, Jatinder Singh

2005-02-01

A technique based on gamma ray spectrometry has been developed for the continuous monitoring of uranium in the solution form. Simulated container and support system was designed and fabricated for the development of an efficiency calibration curve and to find the detection limit for the estimation of uranium using 185.7 keV ( 235 U) gamma ray. The system was calibrated for its counting efficiency using HPGe detector system, in a standard source mount to detector geometry. The sensitivity of the detection system and counting time for low-level estimation of uranium has also been established. The detection limit of the monitor is ∼10 mg of uranium per litre of the solution. In order to correct for the density variation of the solution experiment was carried to study the variation of count rate of 185.7 ke V gamma ray of 235 U as a function of the density of the solution. This report gives the details of the development of a continuous monitor for the determination of uranium in the solution streams. (author)

Study on segregation of aluminium-uranium alloys

International Nuclear Information System (INIS)

Lima, Rui Marques de

1979-01-01

The relations between alloy solidification and solute segregation were considered. The solidification structure and the solute redistribution during the solidification of alloys with dendritic micro morphology were studied. The macro and micro segregation theories were reviewed. The mechanisms that could change the solidification structure were taken into account in the context of more homogeneous alloy production. Aluminum alloys solidification structures and segregation were studied experimentally in the 13 to 45% uranium range, usually considering solidification in static molds. The uranium alloys with up to 20% uranium were studied both for solidification in ingot molds and for controlled directional solidification. It was verified that these alloy compositions had structures similar to those of hipoeutectic alloys, showing an a phase with dendritic morphology and inter dendritic eutectic. For the alloys with more than 25% uranium, it was observed the formation of UAl 3 and UAl 4 phases with dendritic morphology. The dendritic UAl 3 , phase morphology was affected both by the solute concentration in the alloy and by the growth rate. The dendritic UAl 3 phase non-singular aspect could be destroyed with decrease of the alloy solute concentration. In the alloys obtained with higher cooling rates it was found a tendency for the formation of substantial quantities of equi axial crystals of the solute enriched phases in the central regions of the ingot upper half. In the more external regions it was observed dendritic growth of these phases, for alloy compositions with over 25% uranium. An adequate reduction in the cooling rate changed the solidification structure form and distribution, as well as the segregation type and intensity. The uranium content in the solidified macro structures is presented as a function of: cooling rate, superheating, mold size, mold form and its temperature, number of remelting and time for the melt homogenization and agitation. It was

Treatment of uranium mining and milling wastewater using biological adsorbents

International Nuclear Information System (INIS)

Tsezos, M.

1983-01-01

Selected samples of waste microbial biomass originating from various industrial fermentation processes and biological treatment plants have been screened for biosorbent properties in conjunction with uranium, thorium and radium in aqueous solutions. Biosorption isotherms were used for the evaluation of biosorptive uptake capacity of the biomass. The biomass was also compared to synthetic adsorbents such as activated carbon. Determined uranium, thorium and radium biosorption isotherms were independent of the initial solution concentrations. Solution pH affected uptake. Rhizopus arrhizus at pH 4 exhibited the highest uranium and thorium biosorptive uptake capacity in excess of 180 Mg/g. It removed about 2.5 and 3.3 times more uranium than the ion exchange resin and activated carbon tested. Penicillium chrysogenum adsorbed 50000 pCi/g radium at pH 7 and at an equilibrium radium concentration of 1000 pCi/L. The most effective biomass types studied exhibited removals in excess of 99% of the radium in solution

Uranium dissolution in hyper-alkaline TMA-OH solutions: Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Cachoir, C.; Salah, S.; Mennecart, T.; Lemmens, K. [Belgian Research Nuclear Centre - SCK-CEN, Boeretang 200, 2400 Mol (Belgium)

2016-07-01

Leaching experiments were performed with depleted UO{sub 2} powders in tetramethylammonium solutions (TMA-OH) at pH 13.5 and 12.5, and at different UO{sub 2} surface area to volume of solution (SA/V) ratio's to determine the solubility and the dissolution kinetics of UO{sub 2} at high pH in absence of cations dominating cementitious waters (Ca, Na, K). The solubility of UO{sub 2} increased from pH 12.5 to 13.5 and by increasing the SA/V ratio up to 100 m{sup -1}. However, no known U secondary-phases were predicted by geochemical calculations to control the measured U-concentrations. We interpreted the UO{sub 2} dissolution process as a 2-step process. For all experiments, we observe a fast initial rate, hydroxo promoted and likely surface controlled. Afterwards the rate is apparently negative at low SA/V over time while it is positive at higher SA/V ratio's. The former is interpreted to be related to a sorption process, while the latter reveals a continuous residual dissolution process. No solubility enhancing effect of U-colloids was observed in the TMA-OH media. However, there is much less uranium colloid formation in TMA-OH tests with low Ca (Na, K) concentration than in previous tests with higher Ca (Na, K) concentrations. This suggests that the colloid formation is promoted by alkali and/or alkali-earth elements.

Link between ore bodies and biosphere concentrations of uranium

International Nuclear Information System (INIS)

Gordon, S.

1992-01-01

A literature review of uranium exploration studies was carried out to determine the size and concentration of uranium anomalies in the biosphere. Fourteen sites were studied and uranium data were obtained for rocks, water-borne sediments, surface waters, groundwaters, soils and plants. Detailed descriptions of the study areas and of their uranium anomalies are provided. No statistical analyses of the data of anomaly sizes was undertaken because of the variation in the scale of the studies and in the threshold values used and the small number of samples for each medium. The threshold values and the size of the anomaly were found to be dependent on the scale of the study and of the sampling density. Sediments and surface waters were found to have the largest uranium dispersion. Although there was a wide range in the anomaly sizes it was possible to assign typical values for each medium. Based on a typical source of 1 km 2 in the rock it was found that anomalies of similar size as the source are expected in soils and plants, anomalies twice as large are typical for sediments and surface waters and anomalies of smaller areas than the source are possible for groundwater. Some limitations to providing typical groundwater anomaly sizes are outlined. Typical maximum concentrations for the sites studied were greater than 1300 ppm for rock, 10 to 110 ppm for sediment, and 5 ppb for surface waters. No typical values were observed for groundwater, soils and plants. Susceptibility of the host rock to leaching and the presence of discharge zones were assessed for their role in biosphere anomalies

Effect of uranium concentrations on plant growth - a control study

International Nuclear Information System (INIS)

Verma, P.C.; Hegde, A.G.; Arey, N.C.

2010-01-01

This paper presents the details of pot culture experiments carried out to study the migration of uranium in soil to plant system. The effect of varying concentration and chemical forms of uranium on shoot and root length, shoot and root weight, leaf area, water potential, chlorophyll contents, soluble protein, total phenol etc. of two test crops were studied. In case of barley crop, the effect of uranium on seed yield and modulation were also studied. 100% germination could be achieved respectively after a period of 36 hours and 28 hours in uranyl acetate and uranyl nitrate in case of cowpea, whereas it is and 48 hours and 24 hours respectively for barley crop. Higher doses of uranium retarded both the speed as well as germination of seeds for tested crops

Uranium Concentration of Contaminated Zone due to the Cover Depth for Self-Disposal

International Nuclear Information System (INIS)

Koo, Dae Seo; Sung, Hyun Hee; Kim, Gye Nam; Kim, Seung Soo; Kim, Il Gook; Han, Gyu Seong; Choi, Jong Won

2016-01-01

To acquire radiation dose under self disposal from them, the study on decontamination of some uranium contaminated soil and concrete wastes was performed using electrokinetic-electrodialytic. In this study, we evaluated radiation dose due to cover depth on contaminated zone such as uranium contaminated soil and concrete wastes under radiation dose limit using RESRAD Version 6.5. At first, the calculation of the radiation dose on the contaminated zone are carried out. The second, the uranium concentration of contaminated zone due to the cover depth are also analyzed. The uranium contaminated soil and concrete wastes under radiation dose limit by decontaminating them have application to self-disposal of contaminated zone. The area of contaminated zone is 1,500 m"2. The thickness of contaminated zone is 2 m. The length parallel to aquifer flow is 43.702m. The age of the residents on contaminated zone is 15 years old. The period of evaluation on the contaminated zone is from regulation exemption of uranium contaminated soil and concrete wastes till 1,000 years. The calculation of the radiation dose on contaminated zone are carried out. The uranium concentration of contaminated zone due to the cover depth was also analyzed. as the cover depth increases, the uranium concentration has an increasing trend. As the cover depth increases, radiation dose of a person has a decreasing trend. As the cover depth increases, the radiation dose of residents has also a decreasing trend.

Uranium Concentration of Contaminated Zone due to the Cover Depth for Self-Disposal

Energy Technology Data Exchange (ETDEWEB)

Koo, Dae Seo; Sung, Hyun Hee; Kim, Gye Nam; Kim, Seung Soo; Kim, Il Gook; Han, Gyu Seong; Choi, Jong Won [KAERI, Daejeon (Korea, Republic of)

2016-05-15

To acquire radiation dose under self disposal from them, the study on decontamination of some uranium contaminated soil and concrete wastes was performed using electrokinetic-electrodialytic. In this study, we evaluated radiation dose due to cover depth on contaminated zone such as uranium contaminated soil and concrete wastes under radiation dose limit using RESRAD Version 6.5. At first, the calculation of the radiation dose on the contaminated zone are carried out. The second, the uranium concentration of contaminated zone due to the cover depth are also analyzed. The uranium contaminated soil and concrete wastes under radiation dose limit by decontaminating them have application to self-disposal of contaminated zone. The area of contaminated zone is 1,500 m{sup 2}. The thickness of contaminated zone is 2 m. The length parallel to aquifer flow is 43.702m. The age of the residents on contaminated zone is 15 years old. The period of evaluation on the contaminated zone is from regulation exemption of uranium contaminated soil and concrete wastes till 1,000 years. The calculation of the radiation dose on contaminated zone are carried out. The uranium concentration of contaminated zone due to the cover depth was also analyzed. as the cover depth increases, the uranium concentration has an increasing trend. As the cover depth increases, radiation dose of a person has a decreasing trend. As the cover depth increases, the radiation dose of residents has also a decreasing trend.

Wet high-intensity magnetic separation for the concentration of Witwatersrand gold-uranium ores and residues

International Nuclear Information System (INIS)

Corrans, I.J.; Levin, J.

1979-01-01

Wet high-intensity magnetic separation (WHIMS) for the concentration of gold and uranium was tested on many Witwatersrand cyanidation residues, and on some ores and flotation tailings. The results varied, but many indicated recoveries of over 60 per cent of the gold and uranium. The main source of loss is the inefficiency of WHIMS for material of smaller particle size than 20μm. The recoveries in the continuous tests were lower than those in the batch tests. The continuous tests indicated an operational difficulty that could be experienced in practice, namely the tendency for wood chips and ferromagnetic particles to block the matrix of the separator. It was decided that a solution to the problem lies in the modification of the separator to allow continuous removal of the matrix for cleaning. A system has been developed for this purpose and is being demonstrated on a pilot-plant scale. Promising results were obtained in tests on a process that combines a coarse grind, gravity concentration, and WHIMS. In the gravity-concentration step, considerable recoveries, generally over 50 per cent, of high-grade pyrite were obtained, together with high recoveries of gold and moderate, but possibly important, recoveries of uranium. A simple model describing the operation of the WHIMS machine in terms of the operating parameters is described. This should reduce the amount of empirical testwork required for the optimization of operating conditions and should provide a basis for scale-up calculations. The economics of the WHIMS process is discussed [af

Immobilization of uranium from aqueous solutions by using natural diatomites

International Nuclear Information System (INIS)

Mokhambetbakr, Kh.E.; Burkitbaev, M.

2008-01-01

In this study, the adsorption of uranium on natural diatomite (as high abundant and low-cost material) obtained from Aktyubinsk (Kazakhstan) has been investigated. The main purpose of this work is the immobilization of uranium from liquid waste by using diatomites. The diatomites under study were subjected to treatment with various conditions. The first sample is the natural sample (D) Natural Diatomite, the second (D H CL) is purified 0,5 N HCl and the third is the Calcined Diatomite (D 9 00). The effects of concentration of uranium, contact time and type of diatomite treatment on the adsorption process were examined.

Optimization of uranium leach mining

International Nuclear Information System (INIS)

Schecter, R.S.; Bommer, P.M.

1982-01-01

The effects of well pattern and well spacing on uranium recovery and oxidant utilization are considered. As expected, formation permeability heterogeneities and anisotropies are found to be important issues requiring careful consideration; however, it also is shown that the oxidant efficiency and the produced uranium solution concentrations are sensitive to the presence of other minerals competing with uranium for oxidant. If the Damkohler number for competing minerals, which measures the speed of the reaction, exceeds that for uranium, the competing mineral will have to be oxidized completely to recover a large proportion of the uranium. If the Damkohler number is smaller, it may be possible to achieve considerable selectivity for uranium by adjusting the well spacing. 9 refs

Uranium concentration in blood samples of Southern Iraqi leukemia patients using CR-39 track detector

International Nuclear Information System (INIS)

Al-Hamzawi, A.A.; Al-Qadisiyah University, Qadisiyah; Jaafar, M.S.; Tawfiq, N.F.

2014-01-01

The simple and effective technique of fission track etch has been applied to determine trace concentration of uranium in human blood samples taken from two groups of male and female participants: leukemia patients and healthy subjects group. The blood samples of leukemia patients and healthy subjects were collected from three key southern governorates namely, Basrah, Muthanna and Dhi-Qar. These governorates were the centers of intensive military activities during the 1991 and 2003 Gulf wars, and the discarded weapons are still lying around in these regions. CR-39 track detector was used for registration of induced fission tracks. The results show that the highest recorded uranium concentration in the blood samples of leukemia patients was 4.71 ppb (female, 45 years old, from Basrah) and the minimum concentration was 1.91 ppb (male, 3 years old, from Muthanna). For healthy group, the maximum uranium concentration was 2.15 ppb (female, 55 years old, from Basrah) and the minimum concentration was 0.86 ppb (male, 5 years old, from Dhi-Qar). It has been found that the uranium concentrations in human blood samples of leukemia patients are higher than those of the healthy group. These uranium concentrations in the leukemia patients group were significantly different (P < 0.001) from those in the healthy group. (author)

Treatment technology of low concentration uranium-bearing wastewater and its research progress

International Nuclear Information System (INIS)

Wei Guangzhi; Xu Lechang

2007-01-01

With growth of the discharged uranium-bearing wastewater capacity, a low cost and effective treatment technology is required to avoid transferring and diffusion of the radioactive nuclides. On the basis of analyses of the source and characteristics of the low-concentration uranium-bearing wastewater, the conventional treatment technologies, such as, flocculating settling, ion exchange, concentration, adsorption, and some innovatory technologies, such as, membrane, microorganism, phytoremediation and zero-valent iron technology are introduced. (authors)

Study on the electrolytic reduction of Uranium-VI to Uranium-IV in a nitrate system

International Nuclear Information System (INIS)

Araujo, B.F. de; Almeida, S.G. de; Forbicini, S.; Matsuda, H.T.; Araujo, J.A. de.

1981-05-01

The determination of the best conditions to prepare hydrazine stabilized uranium (IV) nitrate solutions for utilization in Purex flowsheets is dealt with. Electrolytic reduction of U(VI) has been selected as the basic method, using an open electrolytic cell with titanum and platinum electrodes. The hydrazine concentration, the current density, acidity, U(VI) concentration and reduction time were the parameters studied and U(IV)/U(VI) ratio was used to evaluate the degree of reduction. From the results it could be concluded that the technique is reliable. The U(IV) solutions remains constant for at least two weeks and can be used in the chemical processing of irradiated uranium fuels. (Author) [pt

Discussion on resin conversion related problems in the process of using ion exchange method to recover uranium from carbonate lixivium in a uranium mine

International Nuclear Information System (INIS)

Yu Suqin; Du Yuhai; Long Qing; Han Wei; Que Weimin

2012-01-01

Ion exchange method was used to recover uranium from carbonate lixivium in a uranium mine, lean resin was converted by sodium bicarbonate solution. Because of high sodium bicarbonate, chlorine and uranium concentration in the converted solution, it is difficult to effectively use. Combined with the production practices of the mine, the resin conversion related problems were analyzed. Some measures were taken for improving utilization rate of the converted solution, and good results were obtained. The utilization rate of the converted solution increased to about 20% from less than lO%, and the consumption of sodium bicarbonate reduced by about 30%. (authors)

Uranium accompanying recovery from copper ores

International Nuclear Information System (INIS)

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

1981-01-01

In the search for new raw material sources for nuclear power engineering a review of the technique of uranium accompaning recovery from copper ores reprocessing products in some countries is presented. In the USA a sorption method of uranium extraction by means of strongly basic ion exchange resins from solutions upon copper case- hardening with subsequent extraction from eluates by solutions of tertiary amines is realized. Elution is realized with sulphuric acid. In South Africa an extraction reprocessing of gravitational concentrate extracted from copper sulphide flotation tailings is organized. In India the uranium extraction from copper ores flotation enrichment tailings is organized on a commerical scale. Presented are data on the scale of uranium recovery, various conditions of its recovery as well as block diagrams of the processes. It is shown that copper ores become an additional source of uranium recovery [ru

Separation and concentration of uranium by extraction chromatography : U(VI) - H3PO4 system

International Nuclear Information System (INIS)

Nobre, J.S.M.

1981-01-01

The feasibility of using the extraction chromatographic technique as a way to recover uranium from phosphatic rocks evaluated. The behaviour of uranium from raw phsophoric acid solutions in chromatographic systems using the mixture di(2-ethylhexyl) orthophosphoric acid (D2EHPA) - tributyl phosphate (TBP) as the stationary phase was studied. Materials as alumina, activated carbon and the macroporous resins XAD-4 and XAD-7 were used as supports for organic stationary phase. The best results were obtained with poliacrilic polymer XAD-7, due to its excellent chromatographic properties and efficient organic phase retention. Uranium was quantitatively retained by D2EHPA-TBP-XAD-7 columns from synthetic phosphoric acid solutions with typical composition of phosphatic acid liquors. The elution of uranium from this system was also studied, and the best results were obtained with phosphoric acid solutions. This chromatographic column presented a high stability, not changing their properties even after more than twenty cycles, including the conditioning, sorption, wasking and elution steps. Uranium determinations were perfpormed by indirect titration with potassium dichromate and by molecular absorption spectrophotometry with hydrogen peroxide- carbonate. A new and more sensitive method for uranium determination in phosphoric medium, which might be applied to acid liquors of phosphatic ores, was developed. An extraction-photometric method was used, with Arsenazo III (1,8-dihydroxynaphtalene-3,6-disulphonic acid-2,7-bis(azo-2)-phenylarsonic acid) as the reagent for uranium. (Author) [pt

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

Optimization of dissolution process parameters for uranium ore concentrate powders

Energy Technology Data Exchange (ETDEWEB)

Misra, M.; Reddy, D.M.; Reddy, A.L.V.; Tiwari, S.K.; Venkataswamy, J.; Setty, D.S.; Sheela, S.; Saibaba, N. [Nuclear Fuel Complex, Hyderabad (India)

2013-07-01

Nuclear fuel complex processes Uranium Ore Concentrate (UOC) for producing uranium dioxide powder required for the fabrication of fuel assemblies for Pressurized Heavy Water Reactor (PHWR)s in India. UOC is dissolved in nitric acid and further purified by solvent extraction process for producing nuclear grade UO{sub 2} powder. Dissolution of UOC in nitric acid involves complex nitric oxide based reactions, since it is in the form of Uranium octa oxide (U{sub 3}O{sub 8}) or Uranium Dioxide (UO{sub 2}). The process kinetics of UOC dissolution is largely influenced by parameters like concentration and flow rate of nitric acid, temperature and air flow rate and found to have effect on recovery of nitric oxide as nitric acid. The plant scale dissolution of 2 MT batch in a single reactor is studied and observed excellent recovery of oxides of nitrogen (NO{sub x}) as nitric acid. The dissolution process is automated by PLC based Supervisory Control and Data Acquisition (SCADA) system for accurate control of process parameters and successfully dissolved around 200 Metric Tons of UOC. The paper covers complex chemistry involved in UOC dissolution process and also SCADA system. The solid and liquid reactions were studied along with multiple stoichiometry of nitrous oxide generated. (author)

Biological processes for concentrating trace elements from uranium mine waters. Technical completion report

International Nuclear Information System (INIS)

Brierley, C.L.; Brierley, J.A.

1981-12-01

Waste water from uranium mines in the Ambrosia Lake district near Grants, New Mexico, USA, contains uranium, selenium, radium and molybdenum. The Kerr-McGee Corporation has a novel treatment process for waters from two mines to reduce the concentrations of the trace contaminants. Particulates are settled by ponding, and the waters are passed through an ion exchange resin to remove uranium; barium chloride is added to precipitate sulfate and radium from the mine waters. The mine waters are subsequently passed through three consecutive algae ponds prior to discharge. Water, sediment and biological samples were collected over a 4-year period and analyzed to assess the role of biological agents in removal of inorganic trace contaminants from the mine waters. Some of the conclusions derived from this study are: (1) The concentrations of soluble uranium, selenium and molybdenum were not diminished in the mine waters by passage through the series of impoundments which constituted the mine water treatment facility. Uranium concentrations were reduced but this was due to passage of the water through an ion exchange column. (2) The particulate concentrations of the mine water were reduced at least ten-fold by passage of the waters through the impoundments. (3) The sediments were anoxic and enriched in uranium, molybdenum and selenium. The deposition of particulates and the formation of insoluble compounds were proposed as mechanisms for sediment enrichment. (4) The predominant algae of the treatment ponds were the filamentous Spirogyra and Oscillatoria, and the benthic alga, Chara. (5) Adsorptive processes resulted in the accumulation of metals in the algae cells. (6) Stimulation of sulfate reduction by the bacteria resulted in retention of molybdenum, selenium, and uranium in sediments. 1 figure, 16 tables

Monitoring of uranium concentrations in water samples collected near potentially hazardous objects in North-West Tajikistan.

Science.gov (United States)

Zoriy, P; Schläger, M; Murtazaev, K; Pillath, J; Zoriy, M; Heuel-Fabianek, B

2018-01-01

The water contamination near ecologically problematic objects was investigated between 2009 and 2014 in North-West Tajikistan as a part of a joint project between Forschungszentrum Jülich and Khujand State University. The main part of this work was the determination of uranium in water samples collected near the Degmay tailings dump, the Taboshar pit lake and the Syr Darya river. More than 130 water samples were collected and analyzed to monitor the uranium concentration near the investigated areas. Two different mass spectrometers and an ion chromatograph were used for element concentration measurements. Based on the results obtained, the uranium influence of the Degmay tailings on the rivers Khoja-Bakyrgan-Say and Syr Darya and surrounding water was not found. The uranium concentration in water samples was monitored for a lengthy period at seven locations Great differences in the uranium concentration in waters collected in 2010, 2011, 2012, 2013 for each location were not observed. Drinking water samples from the region of North-West Tajikistan were analyzed and compared with the World Health Organization's guidelines. Seven out of nine drinking water samples near Taboshar exceeded the WHO guideline value for uranium concentrations (30 μg/L). The average uranium concentration of water samples from Syr Darya for the period from 2009 to 2014 was determined to be 20.1 (±5.2) μg/L. The uranium contamination of the Syr Darya was determined from the western border to the eastern border and the results are shown in this paper. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bois-Noirs ore. Recovery of uranium of solutions from acid treatment. Results of industrial tests at the Gueugnon plant; Minerai des Bois-Noirs. Recuperation de l'uranium des solutions d'attaques acides. Resultats des essais industriels effectues a l'usine de Gueugnon

Energy Technology Data Exchange (ETDEWEB)

Le Bris, J

1959-04-01

Industrial-scale tests are reported of the efficiency of two recovery processes for the separation of uranium from sulfuric acid pickling solutions used on ore from Bois-Noirs, at the Gueugnon works. The final stage of each process is sodium uranate. The earlier part of the report deals with tests of the separation of uranium from foreign metals by fractional precipitation. The second part deals with the separation of uranium from these metals by carbonation of the solutions. (author) [French] Le present rapport concerne les essais industriels de deux procedes de recuperation de l'uranium de solutions d'attaque sulfurique du minerai des Bois-Noirs a l'usine de Gueugnon. Le stade final pour ces deux procedes etant l'uranate de sodium, une premiere partie est consacree aux essais de separation de l'uranium des metaux etrangers par precipitation fractionnee; une deuxieme partie est consacree aux essais de separation de l'uranium des metaux etrangers par carbonatation des solutions d'attaque du minerai. (auteur)

Proserpine - plutonium 239 - Proserpine - uranium 235 - comparison of experimental results

International Nuclear Information System (INIS)

Brunet, J.P.; Caizergues, R.; Clouet D'Orval, Ch.; Kremser, J.; Moret-Bailly, J.; Verriere, Ph.

1964-01-01

The Proserpine homogeneous reactor is constituted by a tank, 25 cm dia, 30 cm high, surrounded by a composite reflector made of beryllium oxide and graphite. In this tank can be made critical plutonium or 90 per cent enriched uranium solutions, the fissile substances being in the form of a dissolved salt. In varying the concentration of the solution, critical masses were studied as a function of the level of the liquid in the tank. The minimum critical mass is 256 ± 2 grs for plutonium and 409 ± 3 grs for uranium 235. In the range of the critical concentrations which were studied, the neutronic properties of fissionable solutions of plutonium and enriched uranium were compared for identical geometries. (authors) [fr

Determination of Oxygen - to - Uranium Ratio in Hyperstoichio - Metric Uranium Dioxide. RCN Report

International Nuclear Information System (INIS)

Tolk, A.; Lingerak, W.A.

1970-09-01

For the determination of the O/U ratio in hyperstoichiometric uranium dioxide we prefer the following chemical procedure. The sample is dissolved in concentrated phosphoric acid without change in valence of the uranium. Then the amount of U (VI) present in the solution is titrated with a Fe (II) - standard solution in phosphoric acid. The titrimetric end-point is detected following the ''dead-stop-end-point'' procedure. When special precautions are made the O/U value can be determined with an accuracy and precision of + 0.0001 0/U units when 500 mg sample aliquots are used. (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)

Uranium problem in production of wet phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

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

1980-01-01

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

Status of technology of uranium recovery from seawater

International Nuclear Information System (INIS)

Sugo, Takanobu; Saito, Kyoichi.

1990-01-01

By bringing the solid material called adsorbent in contact with seawater, uranium can be collected, therefore, the adsorbent to which uranium was adsorbed in seawater can be regarded as the resource of uranium storing. To the adsorbent, also rare metals are concentrated in addition to uranium. From such viewpoint, the development of the technology for collecting seawater uranium is important for the Japanese energy policy. The uranium concentration in seawater is about 3 mg/m 3 and its form of dissolution is uranyl tricarbonate ions. The technology of collecting seawater uranium is the separation technology for extracting the component of very low concentration from the aqueous solution containing many components. The total amount of uranium in the whole oceans reaches about 4 billion t, which is about 1000 times as much as the uranium commercially mined on land. It is the target of the technology to make artificial uranium ore of as high quality as possible quickly. The process of collecting seawater uranium comprises adsorption, desorption, separation and enrichment. As the adsorbents, hydrated titanium oxide and chelate resin represented by amidoxime are promising. The adsorption system is described. (K.I.)

Uranium concentration measurements in human blood for some governorates in Iraq using CR-39 track detector

International Nuclear Information System (INIS)

Tawfiq, N.F.; Ali, L.T.; Al-Jobouri, H.A.

2013-01-01

The sensitive and simple technique of fission track etch has been applied to determine trace concentration of uranium in blood samples for occupational and non-occupational workers, male and female, using CR-39 track detector that is employed for registration of induced fission tracks. The results show that the highest recorded uranium concentration in human blood of workers in the ministry of Science and Technology were 1.90 ppb (male, 36 years old, 12 years' work experience, and living in Basrah governorate) and minimum concentration 0.26 ppb (female, 40 years old, 10 years' work experience, and living in Baghdad), while for non-occupational worker, the maximum uranium concentration was 1.76 ppb (female, 63 years old, and living in Al-Muthana) and minimum concentration was 0.28 ppb (female, 20 years old, and living in Baghdad). It has also been found that the uranium concentration in human blood samples of workers in the ministry of Science and Technology are higher than those of non-occupational workers, and the uranium concentrations for female workers and for non-occupational workers were higher than those for male workers and non-occupational workers. (author)

Application of acid dissolution and natural evaporation to wet cake containing uranium

International Nuclear Information System (INIS)

Kim, Kil J.; Kang, Il Sik; Shon, Jong S.; Hong, Kwon P.

2005-01-01

Chemical wastes containing small amounts of uranium cause environmental problems, if those wastes exceed the concentration of the EPA standard, 20 μg.. /L, and the concentrated sludge should be additionally dried and packaged into a drum, and categorized as a radioactive waste. Diphosil resin is developed to specifically remove actinides or multivalent metals. The immobilization technique is adopted to make a bead form of Diphosil by embedding into sodium alginate, and adsorption characteristics for uranium are reported for a simulated waste solution. In this study, acid dissolution is applied to dissolve uranium from the precipitates of sludge or the dewatered cake in the reduced volume of wastes solution, and removal characteristics of uranium is experimented. From the results, the most effective treatment method for the dissolved solution is suggested

Environmental impact of solution mining for uranium

International Nuclear Information System (INIS)

Hunkin, G.G.

1975-01-01

Compared with most other mining systems, uranium solution mining has a negligible effect on such environmental factors as surface disturbance, interference with natural groundwater quality and distribution, and aerial discharge of radionuclides. The following topics are discussed: the process, personnel safety and health, tailings disposal, impact on groundwater, operating licenses and controls, legislation, and economics. It is concluded that engineered well systems and controlled input/production flow rates, combined with full recirculation systems that maintain constant fluid volumes in the mineralized formations, result in containment of leach solutions within the operating area. The very dilute leach solutions, compatible with natural groundwaters, ensure that no environmental damage results, even if a loss of control occurred. Reduction in the number of processing steps and virtual elimination of operator hazards, waste disposal and land rehabilitation costs help in reducing overall costs

Preliminary results from uranium/americium affinity studies under experimental conditions for cesium removal from NPP ''Kozloduy'' simulated wastes solutions

International Nuclear Information System (INIS)

Nikiforova, A.; Kinova, L.; Peneva, C.; Taskaeva, I.; Petrova, P.

2005-01-01

We use the approach described by Westinghouse Savannah River Company using ammonium molybdophosphate (AMP) to remove elevated concentrations of radioactive cesium to facilitate handling waste samples from NPP K ozloduy . Preliminary series of tests were carried out to determine the exact conditions for sufficient cesium removal from five simulated waste solutions with concentrations of compounds, whose complexing power complicates any subsequent processing. Simulated wastes solutions contain high concentrations of nitrates, borates, H 2 C 2 O 4 , ethylenediaminetetraacetate (EDTA) and Citric acid, according to the composition of the real waste from the NPP. On this basis a laboratory treatment protocol was created. This experiment is a preparation for the analysis of real waste samples. In this sense the results are preliminary. Unwanted removal of non-cesium radioactive species from simulated waste solutions was studied with gamma spectrometry with the aim to find a compromise between on the one hand the AMP effectiveness and on the other hand unwanted affinity to AMP of Uranium and Americium. Success for the treatment protocol is defined by proving minimal uptake of U and Am, while at the same time demonstrating good removal effectiveness through the use of AMP. Uptake of U and Am were determined as influenced by oxidizing agents at nitric acid concentrations, proposed by Savannah River National laboratory. It was found that AMP does not significantly remove U and Am when concentration of oxidizing agents is more than 0.1M for simulated waste solutions and for contact times inherent in laboratory treatment protocol. Uranium and Americium affinity under experimental conditions for cesium removal were evaluated from gamma spectrometric data. Results are given for the model experiment and an approach for the real waste analysis is chosen. Under our experimental conditions simulated wastes solutions showed minimal affinity to AMP when U and Am are most probably in

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

International Nuclear Information System (INIS)

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

1996-01-01

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

Preparation of uranium-based oxide catalysts; Preparation de catalyseurs oxydes a base d'uranium

Energy Technology Data Exchange (ETDEWEB)

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

1965-07-01

We have studied the thermal decomposition of uranyl and uranium IV oxalates as a mean of producing uranium dioxide. We have isolated the main intermediate phases of the decompositions and have indexed the lines of their X-ray diffraction patterns. The oxides produced by the decomposition are ill-defined and unstable: they strongly absorb atmospheric oxygen with modification of the composition and, in certain cases, of the structure (pyrophoric oxide). With a view to obtaining stable oxides, we have prepared mixed uranium-thorium oxalates. In order to prepare an oxalate having a homogeneous composition, it is necessary to adopt a well-defined preparation method: the addition of solutions of thorium and uranium IV nitrates to a continually saturated oxalic acid solution. The mixed oxide obtained from the thermal decomposition of an oxalate U{sub x}Th{sub 1-x}(C{sub 2}O{sub 4}){sub 2}, 2 H{sub 2}O at 500 C for 24 hours in a current of oxygen leads to a cubic structure which is well-defined both in the bulk and superficially when x is less than 0.35. Above this atomic concentration of uranium, some uranium moves out of the lattice in the form of UO{sub 3} or U{sub 3}O{sub 8} according to the temperature. The mixed oxide is not stoichiometric,(U{sub x}Th{sub 1-x}O{sub 2+y}) and the average degree of oxidation of the uranium varies with the temperature and partial oxygen pressure. The oxides thus formed have a high surface area. By dissolving the mixed oxalates in a concentrated solution of ammonium oxalate, it is possible to deposit the catalyst on a support, but the differences in the solubilities of the thorium and uranium IV oxalates in the ammonium oxalate make it impossible to prepare double salts formed either of thorium and uranium and of ammonium. (author) [French] Nous avons etudie la decomposition thermique des oxalates d'uranyle et d'uranium IV en vue d'aboutir au dioxide d'uranium. Nous avons pu isoler les principales phases

Chemistry of Uranium in brines related to the spent fuel disposal in a salt repository. Part I

International Nuclear Information System (INIS)

Diaz Arocas, P.; Grambow, B.

1993-01-01

This report describes the work performed from september 1991 to december 1992. Our work is focused on the chemistry of uranium in highly saline solution. Experiments were performed to study the formation process and the stability of solid phases of U(VI) in NaCl solution at different ionic strength. The characterization of solid phases and of uranium concentration in solution are reported as a function of time. Experiments in NaClO 4 at low concentration have been performed for comparison. A method is proposed for uranium analyses in highly concentrated salt solution. The work has been carried out in KfK (INE), Germany. (Author) 10 figs

Neptunium separation in trace levels from uranium solutions by extraction chromatography

International Nuclear Information System (INIS)

Cotrim, M.B.; Matsuda, H.T.

1994-01-01

Neptunium and uranium behavior in extraction chromatograph system, aiming the separation of micro quantities of neptunium from uranyl solutions is described. Tri-n-octylamine (TOA), Tri-n-butylphosphate (TBP) as stationary phase, alumine, Voltalef UF-300 as support material were verified. The impregnation conditions as well as the best stationary phase/support material ratio were established. TBP/alumine, TBP/Voltalef and TOA/alumine system were selected to uranium and neptunium separation studies. (author) . 12 refs., 03 tabs., 03 figs

Uranium extraction from Uro area phosphate ore, Nuba mountains, Sudan

International Nuclear Information System (INIS)

Mohammed, A. A.; Eltayeb, M. A. H.

2003-01-01

This study was carried out mainly to extract uranium from Uro area phosphate ore in the eastern part of Nuba mountains near Abu Gibiha town in southern Kurdufan state. For this purpose first, the phosphate ore samples were decomposed with sulphuric acid. the resulting phosphoric acid was filtered off, and pretreated with pyrite and activated charcoal. the chemical analysis of the obtained grain phosphoric acid showed that about 98% of uranium content of the phosphate ore was rendered soluble in the phosphoric acid. The clear green phosphoric acid was introduced to uranium extraction by 25% tributylphosphate (Tbp) in kerosene. The effect of several factors on the extraction and stripping processes namely, interference's effect, the suitable strip solution, the required number of extraction and stripping stages, the optimum phase ratio have been studied in details. A three stage extraction at a phase ratio (aqueous/organic) of 1:2, followed by two stages stripping using 0.5 M sodium carbonate solution at a phase ratio (A/O) of 1:4 were found to be the optimum conditions to report more than 98% of uranium content in green phosphoric acid to the aqueous phase as uranyl tricarbonate complex (UO 2 (CO 3 ) 3 ) 4- . By applying sodica decomposition upon the stripping carbonate solution using 50% sodium hydroxide, about 98% of uranium content was precipitated as sodium diuranate concentrate (Na 2 U 2 O 7 ). The chemical analysis using atomic absorption spectrometry (Aas) showed a good agreement between the specification of the obtained uranium concentrate with the standard commercial specification of sodium diuranate concentrate. Further purification was achieved for the yellow cake by selective precipitation of uranium from the solution as uranium peroxide (UO 4 .2H 2 O) using 30% hydrogen peroxide. Finally the uranium peroxide precipitated was calcined at 450 degree C to obtain the orange powder uranium trioxide (UO 3 ). The chemical analysis of the final uranium trioxide

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

International Nuclear Information System (INIS)

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

1997-01-01

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH = 7.0 ± 1.5 over a wide range of temperatures. (author)

Acid pressure leaching of a concentrate containing uranium, thorium and rare earth elements

International Nuclear Information System (INIS)

Lan Xinghua; Peng Ruqing.

1987-01-01

The acid pressure leaching of a concentrate containing rinkolite for recovering uranium, thorium and rare earth elements is described. The laboratory and the pilot plant test results are given. Under the optimum leaching conditions, the recovery of uranium, thorium and rare earth elements are 82.9%, 86.0% and 88.3% respectively. These results show that the acid pressure leaching process is a effective process for treating the concentrate

Developments in uranium solution mining in Australia

International Nuclear Information System (INIS)

Hunter, T.

2001-01-01

The last five years have seen rapid developments in uranium solution mining in Australia, with one deposit brought into production (Beverley, 1,000 tpa U 3 O 8 ) and another close to receiving development approval (Honeymoon, 500 expanding to 1,000 tpa U 3 O 8 proposed). The deposits were discovered during extensive exploration of the Frome Basin in South Australia in the early 1970s and were mothballed from 1983 to 1996 due to Government policies. Uranium mineralisation at Beverley, Honeymoon and other related prospects is hosted in unconsolidated coarse grained quartz sands which are sealed in buried palaeovalleys. Both projects have successfully trialled acid leaching methods and have confirmed high permeability and confinement of the target sands. At Beverley an ion exchange process has been adopted, whereas at Honeymoon solvent extraction has been trialled and is proposed for future production Australian production economics compare favourably with US counterparts and are likely to be within the lower quartile of world costs

Comparison of effect of TDS and Fe in uranium measurement in LED and Xe lamp based fluorimeter

International Nuclear Information System (INIS)

Sahoo, S.K.; Mohapatra, S.; Lenka, P.; Dubey, J.S.; Patra, A.C.; Thakur, V.K.; Ravi, P.M.; Tripathi, R.M.

2014-01-01

In the present study, the effect of TDS and Fe on uranium fluorescence in water samples is studied by fluorometric techniques based on LED and xenon lamp systems. Fluorimeters are calibrated with uranium standards to establish the relationship between concentration and fluorescence response. Known concentration of uranium standard solution is measured in both LED and Xe lamp based fluorimeter after spiking with a series of concentration of Fe and TDS solution. Most often high levels of TDS are caused by the presence of K, CI, Na, etc. Thus here the effect of TDS is studied with NaCI solution but the effect may differ with the presence other elements. Details of the optimization procedure and measurement of uranium concentration in fluorometric technique are given elsewhere. In LED based system, sodium pyrophosphate with phosphoric acid is used as the complexing agent while sodium polysilicate is used in Xe lamp based system. Fe standard solution of 0.1 to 10 ppm was spiked with known uranium standard and analysed in both the fluorimeters. The fluorescence response gradually decreased upto 50% with 10 ppm of Fe in the solution in the LED based system whereas there was a gradual decrease of fluorescence response with increase in Fe concentration and it was 60% with 10 ppm of Fe. Thus both the instruments show nearly equal response with the increasing concentration of Fe in sample solution. Therefore, in case of high TDS and Fe content in the sample, precautions should be taken during measurement of uranium in water samples directly by fluorimetric techniques

Fixation and separation of the elements thorium and uranium using anion exchange resins in nitrate solution; Fixation et separation des elements thorium et uranium par les resines echangeuses d'anions en milieu nitrate

Energy Technology Data Exchange (ETDEWEB)

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

1967-10-01

The exchange of thorium and uranium between a strong base anion resin and a mixed water + ethanol solvent containing nitrate ions is studied. It is assumed that in the resin the thorium and uranium are fixed in the form of the complexes Th(NO{sub 3}){sub 6}{sup 2-} and UO{sub 2}(NO{sub 3}){sub 4}{sup 2-} in solution these elements are present in the form of complexes having the general formula: Th(NO{sub 3}){sub 6-n}{sup n-2} and UO{sub 2}(NO{sub 3}){sub 4-n}{sup n-2} It has been possible to deduce a law for the changes in the partition functions of thorium and uranium as a function of the concentrations of the various species in solution and of the complexing ion NO{sub 3}. From this has been deduced the optimum operational conditions for separating a mixture of these two elements. Finally, in these conditions, the influence of a few interfering ions has been studied: Ba, Bi, Ce, La, Mo, Pb, Zr. The method proposed can be used either as a preparation, or for the dosage of thorium by a quantitative separation. (author) [French] On etudie l'echange du thorium et de l'uranium entre une resine anion base forte et un solvant mixte eau + ethanol charge en ions nitrates. On a suppose que, dans la resine, le thorium et l'uranium sont fixes sous forme de complexes Th(NO{sub 3}){sub 6}{sup 2-} et UO{sub 2}(NO{sub 3}){sub 4}{sup 2-} en solution, ces elements sont engages dans des complexes de formule generale: Th(NO{sub 3}){sub 6-n}{sup n-2} and UO{sub 2}(NO{sub 3}){sub 4-n}{sup n-2} On a pu degager une loi de variation des coefficients de partage du thorium et de l'uranium en fonction des concentrations des diverses especes en solution et de l'anion complexant NO{sub 3}{sup -}. On en a deduit les conditions operatoires optimales necessaires pour separer les deux elements a partir de leurs melanges. Enfin, dans ces conditions, on a etudie l'influence de quelques elements genants: Ba, Bi, Ce, La, Mo, Pb, Zr. La methode preconisee peut etre

Thermal expansion studies on uranium-neodymium mixed oxide solid solutions

International Nuclear Information System (INIS)

Panneerselvam, G.; Venkata Krishnan, R.; Antony, M.P.; Nagarajan, K.

2012-01-01

Uranium-Neodymium mixed oxides solid solutions (U 1-y Nd y ) O 2 (y=0.2-0.95) were prepared by combustion synthesis using citric acid as fuel. Structural characterization and computation of lattice parameter was carried out from room temperature X-ray diffraction measurements. Single-phase fluorite structure was observed up to y=0.80. For solid solutions with y>0.80 additional Nd 2 O 3 lines were visible

Development of uranium milling and conversion

International Nuclear Information System (INIS)

Takada, Shingo; Hirono, Shuichiro.

1983-11-01

The development and improvement of uranium milling and refining producing uranium tetrafluoride from ores by the wet process, without producing yellowcake as an intermediate product, have been carried out for over ten years with a small pilot plant (50 t-ore/day). In the past several years, a process for converting uranium tetrafluoride into hexafluoride has been developed successfully. To develop the process further, the construction of an integrated milling and conversion pilot plant (200 t-U/year) started in 1979 and was completed in 1981. This new plant has two systems of solvent extraction using tri-noctylamine: one of the systems treats the pregnant solution (uranyl sulphate) by heap-leaching followed by ion exchange, and the other treats the uranyl sulphate solution by dissolving imported yellowcake. The uranium loading solvents from the two systems are stripped with hydrochloric acid solution to obtain the concentrated uranium solution containing 100 g-U/1. Uranyl sulphate solution from the stripping circuit is reduced to a uranous sulphate solution by the electrolytic method. In a reduction cell, uranyl sulphate solution and dilute sulphuric acid are used respectively as catholyte and anolyte, and a cation exchange membrane is used to prevent re-oxidation of the uranous sulphate. In the following hydrofluorination step, uranium tetrafluoride, UF 4 .1-1.2H 2 O (particle size: 50-100μ), is produced continuously as the precipitate in an improved reaction vessel, and this makes it possible to simplify the procedures of liquid-solid separation, drying and granulation. The uranium tetrafluoride is dehydrated by heating to 350 0 C in an inert gas flow. The complete conversion from UF 4 into UF 6 is achieved by a fluidized-bed reactor and a high value of utilization efficiency of fluorine, over 99.9 percent, is attained at about 400 0 C. (author)

Uranium uptake by hydroponically cultivated crop plants

Energy Technology Data Exchange (ETDEWEB)

Soudek, Petr; Petrova, Sarka [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Benesova, Dagmar [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Faculty of Environment Technology, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Dvorakova, Marcela [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Vanek, Tomas, E-mail: vanek@ueb.cas.cz [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic)

2011-06-15

Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC{sub 50} value about 0.1 mM. Cucumis sativa represented the most resistant plant to uranium (EC{sub 50} = 0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1 mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1 mM or 0.5 mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. - Highlights: > The uranium accumulation in twenty different plant species varied from 0.160 to 0.011 mg/g DW. > Uranium is mainly localized in the root system. > Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba. > The phosphates deficiency increase the uranium uptake.

Uranium uptake by hydroponically cultivated crop plants

International Nuclear Information System (INIS)

Soudek, Petr; Petrova, Sarka; Benesova, Dagmar; Dvorakova, Marcela; Vanek, Tomas

2011-01-01

Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC 50 value about 0.1 mM. Cucumis sativa represented the most resistant plant to uranium (EC 50 = 0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1 mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1 mM or 0.5 mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. - Highlights: → The uranium accumulation in twenty different plant species varied from 0.160 to 0.011 mg/g DW. → Uranium is mainly localized in the root system. → Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba. → The phosphates deficiency increase the uranium uptake.

Sorption of uranium anionic species from aqueous solutions on HDTMA-bentonite Jelsovy potok

International Nuclear Information System (INIS)

Krajnak, A.; Viglasova, E.; Galambos, M.; Rosskopfova, O.

2014-01-01

Bentonite deposit Jelsovy potok in Slovakia has great potential for use as a engineering barrier in the multi-barrier system of deep geological repository. In this paper, HDTMA-modified bentonite J15m from Slovak bentonite Jelsovy potok was prepared and its sorption properties (sorption isotherms, kinetics) towards anionic uranium species was investigated. The removal of uranium anionic species from aqueous solutions (initial concentration: 10-1,000 mg/L) by J15m was studied in the absence of background electrolytes at initial pH range (pH init ) 8.5; 9.5; 10.5. The amount of the sorbed U was determined spectrophotometrically using the Arsenazo III method. The maximum uptake capacity observed was 31.35 (mg/g) at 298 K. Experimental results were analysed by the Langmuir, Freundlich Dubinin-Redushkevich and Tempkin isotherm. The kinetics of adsorption of U(VI) ions was also discussed using the pseudo-first-order and the pseudo-second-order at three different temperatures. The activation energy of the sorption for J15m was calculated as 23.534 kJ·mol -1 . (authors)

Extraction kinetics of uranium (VI) with polyurethane foam

International Nuclear Information System (INIS)

Huang, Ting-Chia; Chen, Dong-Hwang; Huang, Shius-Dong; Huang, Ching-Tsven; Shieh, Mu-Chang.

1993-01-01

The extraction kinetics of uranium(VI) from aqueous nitrate solution with polyether-based polyurethane foam was investigated in a batch reactor with automatic squeezing. The extraction curves of uranium(VI) concentration in solution vs. extraction time exhibited a rather rapid exponential decay within the first few minutes, followed by a slower exponential decay during the remaining period. This phenomenon can be attributed to the presence of two-phase structure, hard segment domains and soft segment matrix in the polyurethane foam. A two-stage rate model expressed by a superposition of two exponential curves was proposed, according to which the experimental data were fitted by an optimization method. The extraction rate of uranium (VI) was also found to increase with increasing temperature, nitrate concentration, and hydration of the cation of nitrate salt. (author)

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

International Nuclear Information System (INIS)

Baran, V.; Moltasova, J.

1982-01-01

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

Fission track ages and uranium concentration of apatites of different rocks of South India

International Nuclear Information System (INIS)

Nand Lal; Nagpaul, K.K.; Nagpal, M.K.

1975-01-01

The uranium concentration and ages of apatite grains of various rocks of South India have been measured by fission track technique. The ages range from 100 m.y. to 730 m.y. whereas uranium concentrations vary from 0.5 to 23.8 atom/million atoms of the apatite mineral. The ages agree well with the Deccan volcanic and Ocean Cycle activities. (author)

Uranium(VI) speciation: modelling, uncertainty and relevance to bioavailability models. Application to uranium uptake by the gills of a freshwater bivalve; Speciation de l'uranium(6), modelisation, incertitude et implication pour les modeles de biodisponibilite. Application a l'accumulation dans les branchies d'un bivalve d'eau douce

Energy Technology Data Exchange (ETDEWEB)

Denison, F.H

2004-07-01

The effects of varying solution composition on the interactions between uranium(VI) and excised gills of the freshwater bivalve Corbicula fluminea have been investigated in well defined solution media. A significant reduction in the uptake of uranium was observed on increasing the concentrations of the uranium complexing ligands citrate and carbonate. Saturation kinetics as a function of uranium concentration at a pH value of 5.0 were observed, indicating that the uptake of uranium is a facilitated process, probably involving one or several trans-membrane transport systems. A relatively small change in the uptake of uranium was found as a function of pH (factor of ca. 2), despite the extremely large changes to the solution speciation of uranium within the range of pH investigated (5.0 - 7.5). A comprehensive review of the thermodynamic data relevant to the solution composition domain employed for this study was performed. Estimates of the uncertainties for the formation constants of aqueous uranium(VI) species were integrated into a thermodynamic database. A computer program was written to predict the equilibrium distribution of uranium(VI) in simple aqueous systems, using thermodynamic parameter mean-values. The program was extended to perform Monte Carlo and Quasi Monte Carlo uncertainty analyses, incorporating the thermodynamic database uncertainty estimates, to quantitatively predict the uncertainties inherent in predicting the solution speciation of uranium. The use of thermodynamic equilibrium modelling as a tool for interpreting the bioavailability of uranium(VI) was investigated. Observed uranium(VI) uptake behaviour was interpreted as a function of the predicted changes to the solution speciation of uranium. Different steady-state or pre-equilibrium approaches to modelling uranium uptake were tested. Alternative modelling approaches were also tested, considering the potential changes to membrane transport system activity or sorption characteristics on

Solvent extraction of uranium (VI) by Amberlite Lsub(A-1)

International Nuclear Information System (INIS)

Kim, S.S.

1977-01-01

The effects of uranium, amine and sulfuric acid concentrate, and temperature on the extraction of uranium(VI) from acidic sulphate solutions by Amberlite Lsub(A-1) in benzene was studied. The extraction of sulfuric acid by Amberlite Lsub(A-1) in benzene was also examined. It was found that 92 to 98 percent extraction was obtained for a uranyl sulphate solution of 5g/1 concentrate containing of 0.2M to 0.3M sulfuric acid, a Amberlite Lsub(A-1) of 5 to 10 percent (weight) in benzene, at a temperature of less than 20 0 C. The mechanism of uranium extraction was discussed on the basis of the resluts obtained. (author)

The distribution of E-centres concentration in the minerals of the wall-rocks of uranium deposit

International Nuclear Information System (INIS)

Kislyakov, Ya.M.; Moiseev, B.M.; Rakov, L.T.; Kulagin, Eh.G.

1975-01-01

Electron paramagnetic resonance was used to investigate the distribution of electron-hole centres caused by natural radioactive irradiation in terrigenous arcosic rocks and their principal mineral components (quartz-feldspar concretions, white and smoky quartz, feldspars). The relationship between concentrations of E-centres and the uranium content of the rocks reflects the genetic features of the uranium mineralization. Taking one specific deposit as an example, the author shows the proportional dependence between uranium content and E-centre concentration. The dependence reflects the practically simultraneous formation of the main mass of epigenetic mineralization. The hypothesis that older (syngenetic) ore deposits may have existed was not confirmed. Despite the long interval between sedimentary accumulation end epigenesis, no significant surplus concentrations of E-centres were found in epigenetic-metamorphic rocks. Anomalous concentrations of uranium and E-centres are caused by uranium migration during later epigenetic processes superimposed on the mesozoic ore-controlling zonality. One result of this migration is the formation in limonitized rocks of ''augen'' ores for which low concentrations of paramagnetic centres are typical. For the study of the distribution of E-centres in rocks from uranium deposits, it is possible to use polymineral mixtures. For the proper interpratation of the data obtained, however, account must be taken of the sensitivity to irradiation of the various mineral components, particularly the various forms of quartz, which is the principal natural dosimeter. (E.G.)

Dissolution of metallic uranium in alkalis

International Nuclear Information System (INIS)

Mondino, Angel V.; Wilkinson, Maria V.; Manzini, Alberto C.

1999-01-01

The dissolution of U metallic foils has been studied in the framework of the development of an improved 99 Mo-production process. The best conditions for the dissolution of uranium foils of approximately 150 μm are the following: a) NaClO concentrations of 0.20 and 0.23 M with NaOH of 0.27 and 0.31 M respectively; b) temperature of the solution, 70 C degrees; c) volume of the solution, 15 ml / cm 2 of uranium foil; d) dissolution time, 30 minutes. (author)

Neptunium separation in trace levels from uranium solutions by extraction chromatography

International Nuclear Information System (INIS)

Figols, M.E.B.

1991-01-01

Neptunium and uranium behavior in extraction chromatography system, aiming the separation of microquantities of neptunium from uranyl nitrate solutions is described. Tri-n-octylamina (TOA), tri-n-butylphosphate (TBP), thenoyltrifluoroacetone (TTA) as stationary phase, alumina, Voltalef-UF-300, silica as support material were verified. The impregnation conditions as well as the best stationary phase/support material ratio were established. TBP/alumina, TBP/Voltalef and TOA/alumina system were selected to uranium and neptunium separation studies. In the system using TBP as extractant agent uranium and neptunium separation was reached by selective elution after the retention of both elements on the column. U-Np separation by selective retention of Np was possible with TOA system. The capacity of the column was the 66.6 mg U/mL and 191.6mg U/mL for the TBP/alumina and TBP/Voltalef systems, respectively. An application of extraction chromatography system in the final phase of irradiated uranium treatment process is proposed. (author)

Concentration of uranium in the drinking and surface water around the WIPP site

International Nuclear Information System (INIS)

Khaing, H.; Lemons, B.G.; Thakur, P.

2016-01-01

Activity concentration of uranium isotopes ( 238 U, 234 U and 235 U) were analyzed in drinking and surface water samples collected in the vicinity of the WIPP site using alpha spectroscopy. The purpose of this study was to investigate the changes in uranium concentrations (if any) in the vicinity of the WIPP site and whether the February 14, 2014 radiation release event at the WIPP had any detectable impact on the water bodies around the WIPP. (author)

New route for uranium concentrate production from Caetite ore, Bahia State, Brazil; dynamic leaching - direct precipitation

Energy Technology Data Exchange (ETDEWEB)

Morais, Carlos A. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)]. E-mail: cmorais@cdtn.br; Gomiero, Luiz A.; Scassiotti Filho, Walter [Industrias Nucleares do Brasil S.A. (INB), Caetite, BA (Brazil)]. E-mails: gomiero@inb.gov.br; scassiotti@inb.gov.br

2007-07-01

The common uranium concentrate production consists of ore leaching, uranium purification/concentration by solvent extraction and uranium precipitation as ammonium diuranate steps. In the present work, a new route of uranium concentrate production from Caetite, BA-Brazil ore was investigated. The following steps were investigated: dynamic leaching of the ground ore with sulfuric acid; sulfuric liquor pre-neutralization until pH 3.7; uranium peroxide precipitation. The study was carried out in bath and continuous circuits. In the dynamic leaching of ground ore in agitated tanks the uranium content in the leached ore may be as low as 100 {mu}g/g U{sub 3}O{sub 8}, depending on grinding size. In the pre-neutralization step, the iron content in the liquor is decreased in 99 wt.%, dropping from 3.62 g/L to 0.030 g/L. The sulfate content in the liquor reduces from 46 g/L to 22 g/L. A calcinated final product assaying 99.7 wt.% U{sub 3}O{sub 8} was obtained. The full process recovery was over 94%. (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

Recovery of uranium from alkaline ore (Tummalapalle) leach solution using novel precipitating method

International Nuclear Information System (INIS)

Biswas, Sujoy; Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.; Chakravartty, J.K.

2014-01-01

The aim of present study is recovery of uranium from such ore leach solution containing 2 O 7 at pH ∼12.5. The average particle size of the MgU 2 O 7 particles was 20 micron and overall uranium recovery was 97%. The composition of final precipitate was characterized using XRD and surface morphology was studied using SEM

Potential for rhizofiltration of uranium using hairy root cultures of Brassica juncea and Chenopodium amaranticolor

International Nuclear Information System (INIS)

Eapen, Susan; Suseelan, K.N.; Tivarekar, Suchita; Kotwal, S.A.; Mitra, R.

2003-01-01

Hairy root cultures of Brassica juncea and Chenopodium amaranticolor were developed by genetic transformation using Agrobacterium rhizogenes. The stable, transformed root systems demonstrated a high growth rate of 1.5-3. g/g dry weight/day in Murashige and Skoog medium. In the present study, hairy root system was used for removal of uranium from the solution of concentration up to 5000 μM. The results indicated that the hairy roots could remove uranium from the aqueous solution within a short period of incubation. B. juncea could take up 20-23% of uranium from the solution containing up to 5000 μM, when calculated on g/g dry weight basis. C. amaranticolor showed a slow and steady trend in taking up uranium, with 13 uptake from the solution of 5000 μM concentration. Root growth was not affected up to 500 μM of uranium nitrate over a period of 10 days

Solid phase extraction of uranium and thorium on octadecyl bonded silica modified with Cyanex 302 from aqueous solutions

International Nuclear Information System (INIS)

Nilchi, A.; Shariati Dehaghan, T.; Rasouli Garmarodi, S.

2013-01-01

A simple and reliable method for rapid extraction and determination of uranium and thorium using octadecyl-bonded silica modified with Cyanex 302 is presented. Extraction efficiency and the influence of various parameters such as aqueous phase pH, flow rate of sample solution and amount of extractant has been investigated. The study showed that the extraction of uranium and thorium increase with increasing pH value and was found to be quantitative at pH 6; and the retention of ions was not affected significantly by the flow rate of sample solution. The extraction percent were found to be 89.55 and 86.27 % for uranium and thorium, respectively. The maximal capacity of the cartridges modified by 30 mg of Cyanex 302 was found to be 20 mg of uranium and thorium. The method was successfully applied to the extraction and determination of uranium and thorium in aqueous solutions. The percentage recovery of uranium and thorium in a number of natural as well as seawater samples of Iran were also investigated and found to be in the range of 85-95%. (author)

URANIUM LEACHING AND RECOVERY PROCESS

Science.gov (United States)

McClaine, L.A.

1959-08-18

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

Influent of Carbonization of Sol Solution at the External Gelation Process on the Quality of Uranium Oxide Kernel

International Nuclear Information System (INIS)

Damunir; Sukarsono

2007-01-01

The influent of carbonization of sol solution at the external gelation process on the quality of uranium oxide kernel was done. Variables observed are the influent of carbon, temperature and time of reduction process of U 3 O 8 kernel resulted from carbonization of sol solution. First of all, uranyl nitrate was reacted with 1 M NH 4 OH solution, producing the colloid of UO 3 . Then by mixing and heating up to the temperature of 60-80 °C, the colloid solution was reacted with PVA, mono sorbitol oleate and paraffin producing of uranium-PVA sol. Then sol solution was carbonized with carbon black of mol ratio of carbon to uranium =2.32-6.62, produce of carbide gel. Gel then washed, dried and calcined at 800 °C for 4 hours to produce of U 3 O 8 kernel containing carbon. Then the kernel was reduced by H 2 gas in the medium of N 2 gas at 500-800 °C, 50 mmHg pressure for 3 hours. The process was repeated at 700 °C, 50 mmHg pressure for 1-4 hours. The characterization of chemical properties of the gel grains and uranium oxide kernel using FTIR covering the analysis of absorption band of infra red spectrum of UO 3 , C-OH, NH 3 , C-C, C-H and OH functional group. The physical properties of uranium oxide covering specific surface area, void volume, mean diameter using surface area meter Nova-1000 and as N 2 gas an absorbent. And O/U ratio of uranium dioxide kernel by gravimetry method. The result of experiment showed that carbonization of sol solution at the external gelation process give influencing the quality of uranium oxide kernel. (author)

Development of an on-line analyzer for organic phase uranium concentration in extraction process

International Nuclear Information System (INIS)

Dong Yanwu; Song Yufen; Zhu Yaokun; Cong Peiyuan; Cui Songru

1998-10-01

The working principle, constitution, performance of an on-line analyzer and the development characteristic of immersion sonde, data processing system and examination standard are reported. The performance of this instrument is reliable. For identical sample, the signal fluctuation in continuous monitoring for four months is less than +-1%. According to required measurement range by choosing appropriate length of sample cell the precision of measurement is better than 1% at uranium concentration 100 g/L. The detection limit is (50 +- 10) mg/L. The uranium concentration in process stream can be automatically displayed and printed out in real time and 4∼20 mA current signal being proportional to the uranium concentration can be presented. So the continuous control and computer management for the extraction process can be achieved

Uranium hydrogeochemical and stream sediment reconnaissance of the Gillette NTMS quadrangle, Wyoming, including concentrations of forty-two additional elements

International Nuclear Information System (INIS)

Warren, R.G.; George, W.E.; Minor, M.M.; Simi, O.R.; Talcott, C.L.; Hensley, W.K.; Cheadle, J.M. III.

1980-08-01

During 1976 and 1977, 752 water and 843 sediment samples were collected from 1419 locations within the 17 700-km 2 area of the Gillette quadrangle, Wyoming. Water samples were collected primarily from wells, and also from springs, ponds, and streams; sediment samples were collected primarily from stream channels, and also from springs and ponds. Each water sample was analyzed for uranium and each sediment sample was analyzed for 43 elements, including uranium and thorium. Uranium concentrations in water samples range from below the detection limit of 0.02 to 212.20 ppB and have a median of 1.10 ppB. The highest background uranium concentrations, as well as the highest individual uranium values, are in areas where favorable host units for uranium mineralization crop out. These units are the Wasatch and Fort Union formations in the Powder River Basin and the Inyan Kara group in the Black Hills. Uranium concentrations in sediment samples range from 0.64 to 29.83 ppM and have a median of 3.24 ppM. Background uranium concentrations are strongly controlled by the exposed geologic unit, and range from 4 to 8 ppM for the Cretaceous Colorado group to 1 to 3 ppM for the Triassic and Paleozoic units exposed in the Black Hills. Several areas where the Wasatch and Fort Union formations are exposed exhibit uranium concentrations in sediment samples that are slightly, but distinctly, above background values for these units. All of these areas are also associated with notably high uranium concentrations in water samples. Because epigenetic uranium mineralization in economically important areas can exhibit a similar geochemical signature, these areas within the Gillette quadrangle should be further examined for the possible presence of uranium mineralization

Distribution of iron during full loading of amberlite IRC-72 resin with uranium from nitrate solutions at 300C

International Nuclear Information System (INIS)

Shaffer, J.H.; Greene, C.W.

1979-01-01

The integrity of resin-based fuel kernels used in the fabrication of fuel elements for a high-temperature gas-cooled reactor will depend, in part, on the concentration of iron incorporated in the resin particles during their loading with uranium. Consequently, assessment of chemical specifications for iron as an impurity in uranyl nitrate solution should be based on its distribution during the resin loading operation. For this purpose, the behavior of iron, as an impurity in uranyl nitrate solutions, was investigated under equilibrium conditions at 30 0 C during full loading of Amberlite IRC-72 cation exchange reaction were derived from calculations based on complex coordination of ferric ion with the resin over the nitrate ion concentration range of approx. 0.5 to 2 N

Maintenance of a labour safety and ecological safety in chinks at extraction of uranium

International Nuclear Information System (INIS)

Svambaev, Z.A.; Svambaev, E.A.; Sultanbekov, G.A; Tusupbekova, S.T.; Svambaev, A.S.

2010-01-01

The authors of scientific work inform results of research on maintenance of a labour safety and ecological safety in chinks at extraction of uranium. Practical actions on increase of safety and a labour safety in chinks at extraction of uranium in opinion of the author is the practical actions directed on perfection of technological processes, development of means of the control and management of technological processes, modernization of the equipment, the organization of safe workplaces of the personnel. It is necessary to give significant attention to actions connected with improvement of physical protection of radioactive dangerous objects. The basic radiating, toxicological danger at the enterprises underground extractions of uranium are natural atoms uranium - the thorium lines, contained in technological solutions, in finished goods, in radioactive waste products, on a surface of the process equipment, vehicles and packings. In manufacture of uranium use highly toxic substances, such as the concentrated sulfuric acid, hydrogen H 2 O 2 , ammonia water with maintenance - not less than 25 %. The technological circuit of reception sour - oxide natural uranium is represented in the following. The solutions acting from uterus sobered after sedimentation from mechanical impurity and after clarification moves in technical unit sonar where it is possible a sulfuric acid and submit through pump down chinks under pressure to uranium horizon where the productive solution of uranium is formed. The productive solution of uranium with the help of deep pumps through pump out chinks acts on unit of reception of a productive solution, then in modular capacity where there is a process clarification, his ambassador moves on sobered to extraction of uranium that is for processing. On a processing complex the productive solution from modular capacity acts on sobered columns in them occurs sobered uranium from a productive solution on ion exchange pitches or so the sorbent, and

Mise en solution et précipitation de l'uranium et du thorium dans les conditions de moyenne et haute température (résumé Solution and Precipitation of Uranium and Thorium under Average and High-Temperature (Summary

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Moreau M.

2006-11-01

Full Text Available Les études tant analytiques qu'expérimentales réalisées au cours des vingt dernières années ont bien montré le rôle joué par les complexes d'uranylcarbonates dans le transport de l'uranium en milieu hydrothermal oxydant ou faiblement réducteur. Les travaux expérimentaux actuels sur la mobilité de U et Th, à haute température et haute pression, montrent la très grande différence de solubilité entre UO2 et ThO2, comme l'influence des ions complexants et celles de fO2 et aH+. Ces résultats expérimentaux sont comparés aux données recueillies sur les leucogranites et les granites calcoalcalins (France et divers gisements ou anomalies en uranium (Québec, Rössing, Madagascar, etc.. Dans la catazone U et Th précipitent sous forme de solutions solides d'uranothorianite dans les milieux déficitaires en silice, et sous forme d'uranothorite dans les granites et les syénites La précipitation d'uraninite non thorifère dans les leucogranites français s'explique d'abord par la faible concentration en thorium des solutions aqueuses durant la phase deutérique. Au cours du métamorphisme progressif on peut observer un retard dans la mobilisation de l'uranium en conditions relativement oxydantes, quand U est associé à Ti et OH. Dans le domaine mésozonal la brannérite stabilise l'uranium en présence de titane jusqu'à l'anatexie. Au-delà elle se dissocie en donnant de l'uraninite non thorifère et du rutile. Both analytic and experimental research done over the Iast twenty years has revealed the role played by uranylcarbonate complexes in the transfer of uranium in an oxidant or slightly reducing hydrothermal medium. Recent experimental research on the mobility of U and Th, at high temperature and high pressure, shows the great difference in solubility between UO2 and ThO2, like the influence of complexing ions and of fO2 and aH+. These experimental findings are compared to data gathered on leucogranites and colcoalkaline granites

Biosorption behaviors of uranium (VI) from aqueous solution by sunflower straw and insights of binding mechanism

International Nuclear Information System (INIS)

Lian Ai; Xuegang Luo; Xiaoyan Lin; Sizhao Zhang

2013-01-01

Uranium (VI)-containing water has been recognized as a potential longer-term radiological health hazard. In this work, the sorptive potential of sunflower straw for U (VI) from aqueous solution was investigated in detail, including the effect of initial solution pH, adsorbent dosage, temperature, contact time and initial U (VI) concentration. A dose of 2.0 g L -1 of sunflower straw in an initial U (VI) concentration of 20 mg L -1 with an initial pH of 5.0 and a contact time of 10 h resulted in the maximum U (VI) uptake (about 6.96 mg g -1 ) at 298 K. The isotherm adsorption data was modeled best by the nonlinear Langmuir-Freundlich equation. The equilibrium sorption capacity of sunflower straw was observed to be approximately seven times higher than that of coconut-shell activated carbon as 251.52 and 32.37 mg g -1 under optimal conditions, respectively. The positive enthalpy and negative free energy suggested the endothermic and spontaneous nature of sorption, respectively. The kinetic data conformed successfully to the pseudo-second-order equation. Furthermore, energy dispersive X-ray, fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that U (VI) adsorption onto sunflower straw was predominantly controlled by ion exchange as well as complexation mechanism. The study revealed that sunflower straw could be exploited for uranium remediation of aqueous streams as a promising adsorbent. (author)

Simulation of transportation of low enriched uranium solutions

International Nuclear Information System (INIS)

Hope, E.P.; Ades, M.J.

1996-01-01

A simulation of the transportation by truck of low enriched uranium solutions has been completed for NEPA purposes at the Savannah River Site. The analysis involves three distinct source terms, and establishes the radiological risks of shipment to three possible destinations. Additionally, loading accidents were analyzed to determine the radiological consequences of mishaps during handling and delivery. Source terms were developed from laboratory measurements of chemical samples from low enriched uranium feed materials being stored at SRS facilities, and from manufacturer data on transport containers. The transportation simulations were accomplished over the INTERNET using the DOE TRANSNET system at Sandia National Laboratory. The HIGHWAY 3.3 code was used to analyze routing scenarios, and the RADTRAN 4 code was used to analyze incident free and accident risks of transporting radiological materials. Loading accidents were assessed using the Savannah River Site AXAIR89Q and RELEASE 2 codes

Simultaneous determination of uranium and plutonium in dissolver solution of irradiated fuel, using ID-TIMS. IRP-11

International Nuclear Information System (INIS)

Shah, Raju; Sasi Bhushan, K.; Govindan, R.; Alamelu, D.; Khodade, P.S.; Aggarwal, S.K.

2007-01-01

A simple sample preparation and simultaneous analysis method to determine uranium and plutonium from dissolver solution, employing the technique of Isotope Dilution Mass spectrometry has been demonstrated. The method used, co-elusion of Uranium and Plutonium from anion exchanger column after initial elution of major part of uranium in 1:5 HNO 3 in order to reduce the initial U/Pu ratio from 1000 to about 100-200 in the co-eluted fraction. Due to the availability of variable multi-collector system, different Faraday cups were adjusted to collect the different ion intensities corresponding to the different masses, during the simultaneous analysis of Uranium and Plutonium, loaded on Re double filament assembly. 233 U and PR grade Plutonium were used as spikes to determine Uranium and Plutonium from dissolver solution of irradiated fuel from research reactor. The possibility of getting the isotopic composition of uranium from the simultaneous analysis of co-eluted purified fraction of U and Pu from spiked aliquots is also explained. (author)

Studies on the determination of uranium by potentiometry

International Nuclear Information System (INIS)

Venkataramana, P.; John, Mary; Nair, P.R.; Kasar, U.M.; Natarajan, P.R.

1981-01-01

A potentiometric method for the determination of uranium standardised earlier has been in use for the chemical quality control of plutonium fuels. The method involves the reduction of U(VI) in phosphoric acid medium and titration of U(IV) against Cr(VI). An extension of the range of the quantity of uranium determined by the same method is reported here. The precisions have been evaluated at 13 concentration levels. 20 titrations were carried out at each concentration. the precision at 20 μg level was found to be 3.8% while it was better than 0.03% at concentrations ranging from 20 mg upto 200 mg. At 100 mg and 200 mg of uranium the total volume of the reagent solutions was 50 ml while in other cases it was 25 ml. The effects of a few impurities on the uranium determination were also studied for the 2-5 mg range of uranium. (author)

Uranium concentrations and 234U/238U activity ratios in fault-associated groundwater as possible earthquake precursors

International Nuclear Information System (INIS)

Finkel, R.C.

1981-01-01

In order to assess the utility of uranium isotopes as fluid phase earthquake precursors, uranium concentrations and 234 U/ 238 U activity ratios have been monitored on a monthly or bimonthly basis in water from 24 wells and springs associated with Southern California fault zones. Uranium concentrations vary from 0.002 ppb at Indian Canyon Springs on the San Jacinto fault to 8.3 ppb at Lake Hughes well on the San Andreas fault in the Palmdale area. 234 U/ 238 U activity ratios vary from 0.88 at Agua Caliente Springs on the Elsinore fault to 5.4 at Niland Slab well on the San Andreas fault in the Imperial Valley. There was one large earthquake in the study area during 1979, the 15 October 1979 M = 6.6 Imperial Valley earthquake. Correlated with this event, uranium concentrations varied by a factor of more than 60 and activity ratios by a factor of 3 at the Niland Slab site, about 70 km from the epicenter. At the other sites monitored, uranium concentrations varied in time, but with no apparent pattern, while uranium activity ratios remained essentially constant throughout the monitoring period

METHOD OF RECOVERING URANIUM COMPOUNDS

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