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    Uranium recovery from UCF liquid waste by nanoporous MCM-41: Breakthrough capacity and elution behavior studies

    , Article Research on Chemical Intermediates ; Volume 39, Issue 3 , 2013 , Pages 951-959 ; 09226168 (ISSN) Mousavi, S. M ; Tavakoli, H ; Samadfam, M ; Semnani, F ; Asadi, Z ; Sepehrian, H ; Sharif University of Technology
    Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min-1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min-1 (61.95 μg g-1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated... 

    Modeling of uranium bioleaching by Acidithiobacillus ferrooxidans

    , Article Annals of Nuclear Energy ; Volume 43 , May , 2012 , Pages 13-18 ; 03064549 (ISSN) Rashidi, A ; Safdari, J ; Roosta Azad, R ; Zokaei Kadijani, S ; Sharif University of Technology
    In this paper, a mathematical model for the mesophilic bioleaching of uraninite is developed. The case of constant temperature, pH, and initial ore concentration is considered. The model is validated by comparing the calculated and measured values of uranium extraction, ferric and ferrous iron in solution, and cell concentration. Good fits of the model were obtained, while the values of the parameters were within the range expected. New rate expressions were used for the iron precipitation and uranium leaching rates. The rates of chemical leaching and ferric precipitation are related to the ratio of ferric to ferrous in solution. The fitted parameters can be considered applicable only to... 

    Fabrication of Nuclear Fuel Pellet With a Mixture of Micro and Nano UO2 Powders And Investigation of Its Physical and Mechanical Properties

    , M.Sc. Thesis Sharif University of Technology Karami, Mahdiyeh (Author) ; Otukesh, Mohammad (Supervisor) ; Taghizade, Mohammad (Supervisor) ; Roshanzamir, Manouchehr (Co-Advisor)
    Uranium dioxide (UO2) has been widely used as nuclear fuel in water cooled reactors since 1960s. UO¬2 is a refractory oxide with a melting point in excess of 28000C and therefore, requires high sintering temperature around 17000C in a hydrogen atmosphere for several hours. In the conventional method, the sintering is incorporated with indirect heating of green pellets in a refractory-type electrical resistance furnace. This furnace, however, uses a large number of expensive heating elements and refractory materials to achieve and maintain the high temperature for a long time. Moreover, it consumes much electrical energy and time. Since nanocrystalline materials contain a large fraction of... 

    Uranium Extraction from Waste Streams of ZPP Plant

    , M.Sc. Thesis Sharif University of Technology Azhdeh, Sahar (Author) ; Samadfam, Mohamad (Supervisor) ; Farhadi, Amir Hossein (Co-Advisor)
    Uranium recovery from wastes produced in every stage of nuclear fuel cycle is very important from both the economic and environmental points of view. Zircon, zirconium-containing ore that is the input feed to Zirconium sponge production factories, contains considerable amounts of uranium compounds. The majority of this uranium will enter to the different waste streams of the plant. In this study, by analyzing the waste streams of the Zirconium Production Plant (ZPP) located at Isfahan, Iran, total mass balance of uranium in waste streams was identified. It was concluded that bottom residuals at furnaces of the chlorination unit is the primary uranium-containing waste stream. The preliminary... 

    Optimization of operating parameters and rate of uranium bioleaching from a low-grade ore

    , Article Journal of Radioanalytical and Nuclear Chemistry ; Vol. 301, issue. 2 , 2014 , pp. 341-350 ; ISSN: 02365731 Rashidi, A ; Roosta-Azad, R ; Safdari, S. J ; Sharif University of Technology
    In this study the bioleaching of a low-grade uranium ore containing 480 ppm uranium has been reported. The studies involved extraction of uranium using Acidithiobacillus ferrooxidans derived from the uranium mine samples. The maximum specific growth rate (μ max) and doubling time (t d) were obtained 0.08 h-1 and 8.66 h, respectively. Parameters such as Fe2+ concentration, particle size, temperature and pH were optimized. The effect of pulp density (PD) was also studied. Maximum uranium bio-dissolution of 100 ± 5 % was achieved under the conditions of pH 2.0, 5 % PD and 35 °C in 48 h with the particles of d 80 = 100 μm. The optimum concentration of supplementary Fe2+ was dependent to the PD.... 

    Uranium Recovery From Liquid Waste of UCF Plant With Ion Exchange Resin Method in Continuous Mode

    , M.Sc. Thesis Sharif University of Technology Semnani, Fatemeh (Author) ; Samadfam, Mohammad (Supervisor) ; Sepehrian, Hamid (Supervisor) ; Ghasemi, Mohammad Reza (Co-Advisor)
    During various stages of processing uranium in Uranium conversion facility (UCF) in Isfahan, significant amounts of liquid waste is produced which leads to evaporation ponds. Since the concentration of uranium in evaporation ponds is relatively high, it seems to addition to environmental issues with recycled uranium from existing pools is also economically. Various physical and chemical methods for removal of uranium waste is used such as solvent extraction, ion exchange, chemical precipitation, membrane processes, etc. Each method has advantages and disadvantages. The ion exchange method, The due to lower cost, less acid pollution with organic copmpounds, convenience and high selectivity... 

    Study on the Factors Affecting in the Thermal Decomposition of Ammonium Uranyl Carbonate (AUC) to Uranium Dioxide (UO2)

    , M.Sc. Thesis Sharif University of Technology Ghannadi Baradaran, Mahdi (Author) ; Otoukesh, Mohammad (Supervisor) ; khanchi, Alireza (Supervisor)
    According to the literature survey, the thermal decomposition of ammonium uranyl carbonate (AUC) is affected by different factors such as its purity and environmental conditions. Thermal treatment of this compound in the air atmosphere results in the production of at least three oxide forms of uranium (UO3, U3O8 and UO2) with different stoichiometric structure. The aim of this project was to study the effects of those parameters which play role in the decomposition of AUC and the production of UO2 compound in the presence of ammonia atmosphere. Therefore, an atmosphere control furnace was designed and constructed to establish the gas in the atmosphere of furnace chamber. On the other hand,... 

    Recovery of uranium from UCF liquid waste by anion exchange resin CG-400: Breakthrough curves, elution behavior and modeling studies

    , Article Annals of Nuclear Energy ; Volume 54 , April , 2013 , Pages 149-153 ; 03064549 (ISSN) Tavakoli, H ; Sepehrian, H ; Semnani, F ; Samadfam, M ; Sharif University of Technology
    Continuous fixed-bed column studies were carried out by using Amberlite CG-400 anion exchange resin for the recovery of uranium from aqueous solutions (synthetic solutions and uranium conversion facility (UCF) liquid waste). Effects of operating parameters such as flow rate and bed height were studied. The breakthrough capacity decreases with increasing flow rate, but this dependence was not significant with a long column. The maximum breakthrough capacity of uranium ions were achieved by CG-400 resin at a flow rate of 0.2 mL min-1 and bed height 9.1 cm (4 g resin). The elution behavior of uranium from CG-400 resin by various eluents have been investigated and the results show that 0.5 mol... 

    Modeling and simulation of flow and uranium isotopes separation in gas centrifuges using implicit coupled density-based solver in OpenFOAM

    , Article European Journal of Computational Mechanics ; Volume 29, Issue 1 , 2020 , Pages 1-26 Ghazanfari, V ; Salehi, A. A ; Keshtkar, A. R ; Shadman, M. M ; Askari, M. H ; Sharif University of Technology
    River Publishers  2020
    The performance of a gas centrifuge that is used for isotopes separation is dependent on the gas flow inside it. In this study, for modeling the UF6 gas flow, an Implicit Coupled Density-Based (ICDB) solver, was developed in OpenFOAM. To validate the ICDB solver, the gas flow within the rotor in total reflux state was compared with the analytical solution obtained by Onsager model and the numerical solution obtained by the Fluent software. The results showed that the ICDB solver had acceptable accuracy and validity. Also the computational efficiency of Roe, AUSM (Advection Upstream Splitting Method) and AUSM+ up schemes were compared. The results showed AUSM+ up scheme is efficient. Then,... 

    Production of high quality ammonium uranyl carbonate from “uranyl nitrate + carbonate” precursor solution

    , Article Progress in Nuclear Energy ; Volume 122 , 2020 Sadeghi, M. H ; Outokesh, M ; Zare, M. H ; Sharif University of Technology
    Elsevier Ltd  2020
    The purpose of this study is to investigate production of high quality ammonium uranyl carbonate (AUC) from “uranyl nitrate + ammonium bicarbonate”, or “uranyl nitrate + sodium carbonate” precursor solutions, by controlled injection of ammonium carbonate solution which could be applicable in material testing reactor (MTR) fuel production plant for recycling of rejected uranium oxide powder. The experimental observations revealed: at pHs higher than 6, precipitation proceeds with formation of no intermediate, thus ensuing a better morphology and size distribution of the AUC products. The results of scanning electron microscopy, X-ray diffraction, particle size analysis, and uranium content... 

    Study on Adsorption of Uranium from Saghand Ore Leach Liquor by Continuous Ion Exchange Systems

    , M.Sc. Thesis Sharif University of Technology Noori Khangah, Behrooz (Author) ; Outokesh, Mohammad (Supervisor) ; Godocynejhad, Davood (Supervisor) ; Saberyan, Kamal (Co-Supervisor) ; Asghari, Reza (Co-Supervisor)
    The current study was attributed to uranium uptake by Varion-AP resin from Saghand, Iran Uranium Mine, ore leach liquor. A suitable high-efficiency system was designed for continuous ion exchange at the bench scale and the uranium uptake parameters were optimized. In this system, 1 reactors was used with a volume of 3 liters in stage with the same height difference. A leach liquor containing uranium with a concentration of between 200 and 300 mg/l was flowed from the feed storage by gravity between reactor 1 to 10 at a flow rate of 30 lit/h and Varion-AP resin was transferred in counter-current flow from stage 10 to 1 by a pneumatic pump. The output of each reactor had a screener that... 

    Uranium Recovery From Liquid Waste of UCF Plant With Ion Exchange Resin Method

    , M.Sc. Thesis Sharif University of Technology Asadi, Zahra (Author) ; Samadfam, Mohammad (Supervisor) ; Sepehrian, Hamid (Supervisor)
    During the various stages of uranium processing in Uranium Conversion Facility (UCF) in Isfahan, significant amounts of liquid waste stream is produced which is sent to evaporation ponds. In addition to environmental considerations, uranium recovery from existing pools is also economically feasible due to high concentration uranium in liquid waste. Several methods have been evolved over the years to remove dissolved uranium from uranium bearing solution. These methods are: chemical precipitation, liquid-liquid extraction, ion exchange and membrane processes. The purpose of this study is recovery of uranium from liquid waste of Isfahan UCF plant by using ion exchange method. Although this... 

    Study on the Kinetics of Uranium Adsorption in the Stirred Reactors, and Search for the Scalable Kinetic Models for This

    , M.Sc. Thesis Sharif University of Technology Hashemi Oalya, Ali (Author) ; Otukesh, Mohammad (Supervisor) ; Khanchi, Alireza (Supervisor)
    One of the main uranium separations of ore that uranium percent application of enhanced design strategies in the industrial cracking furnaces are of practical interest for oil, gas and petrochemical industries. For such engineering purposes the exact simulation of temperature, species concentration and flow fields in the furnace is essential. In this paper, a study was performed to simulate 3D flue gas flow pattern, temperature and species concentration field in the radiation section of an industrial cracking furnace using the computational fluid dynamics (100-500) ppm technique. The steady-state Reynolds Averaged Navier–Stokes (Resin in pulp)equations were solved, in a finite volume scheme,... 

    Startup of "cANDLE" burnup in a Gas-cooled Fast Reactor using Monte Carlo method

    , Article Annals of Nuclear Energy ; Volume 50 , December , 2012 , Pages 44-49 ; 03064549 (ISSN) Kheradmand Saadi, M ; Abbaspour, A ; Pazirandeh, A ; Sharif University of Technology
    During the past decade, the CANDLE burnup strategy has been proposed as an innovative fuel cycle and reactor design for complete utilization of uranium resources. In this strategy the shapes of neutron flux, nuclide densities and power density distribution remain constant but the burning region moves in axial direction. The feasibility of this strategy has been demonstrated widely by using the diffusion technique in conjunction with nuclide transmutation equations. On the other hand since the Monte Carlo method provides the exact solution to the neutron transport, the Monte Carlo technique is becoming more widely used in routine burnup calculations. The main objective of this work is startup... 

    Studies on the recovery of uranium from nuclear industrial effluent using nanoporous silica adsorbent

    , Article International Journal of Environmental Science and Technology ; Volume 9, Issue 4 , October , 2012 , Pages 629-636 ; 17351472 (ISSN) Sepehrian, H ; Samadfam, M ; Asadi, Z ; Sharif University of Technology
    Springer  2012
    In this paper, the sorption of uranium onto nanoporous silica adsorbent in the presence of nitrate, sulfate, chloride, fluoride and phosphate was studied. The effect of contact time between the nanoporous sorbent and aqueous solution, pH and initial concentration of uranium was also investigated. Uranium sorption onto nanoporous silica adsorbent is a very fast process as sorption rate increases with pH increment. Optimum pH for uranium sorption was 4-8. Experimental sorption isotherm is successfully described by Langmuir and Freundlich models. The results obtained by batch experiments showed that the presence of high concentration of nitrate, sulfate, chloride and phosphate anions alone had... 

    Uranium(VI) sorption behavior onto amberlite CG-400 anion exchange resin: Effects of pH, contact time, temperature and presence of phosphate

    , Article Annals of Nuclear Energy ; Volume 48 , October , 2012 , Pages 21-24 ; 03064549 (ISSN) Semnani, F ; Asadi, Z ; Samadfam, M ; Sepehrian, H ; Sharif University of Technology
    Elsevier  2012
    In this paper, uranium sorption onto amberlite CG-400 anion exchange resin in the presence of phosphate anions was studied. The effect of contact time between the sorbent and aqueous solution, pH, initial concentration of uranium and temperature were also investigated. Kinetic studies show that uranium sorption onto amberlite CG-400 resin in the presence of phosphate is a fast process and follows pesudo-second-order kinetics. It was also found that the pH value and the presence of phosphate play very important roles in the uranium sorption onto CG-400 resin. Optimum pH for uranium sorption in the presence of phosphate anions was about 3.5. The experimental sorption isotherm is successfully... 

    Recovery of uranium from carbonaceous radioactive waste of the UF6 production line in a uranium conversion plant: Laboratory and pilot plant studies

    , Article Hydrometallurgy ; Volume 205 , 2021 ; 0304386X (ISSN) Sadeghi, M. H ; Outokesh, M ; Sharifi, M ; Habibi Zare, M ; Sharif University of Technology
    Elsevier B.V  2021
    Carbonaceous radioactive waste is produced by adsorption of effluent gases of UF6 production line, on a bed of charcoal. Current research was aimed at developing a process for recovery of uranium from this waste in a laboratory and at pilot scale. As a first step, leaching of uranium from carbonaceous radioactive waste was undertaken by successive steps using Al(NO3)3 and nitric acid, the former used to eliminate corrosivity of the F− ions. The stoichiometry of reaction between F− and Al3+ ions form complexes ranging from AlF2+, AlF2+ to AlF3 depending upon their molar ratio. The results showed that the increase of NO3−/U ratio increased the uranium leaching efficiency. Presence of some... 

    Kinetic and thermodynamic studies of uranium(VI) adsorption using Amberlite IRA-910 resin

    , Article Annals of Nuclear Energy ; Volume 39, Issue 1 , January , 2012 , Pages 42-48 ; 03064549 (ISSN) Rahmati, A ; Ghaemi, A ; Samadfam, M ; Sharif University of Technology
    Thermodynamic and kinetic studies have been carried out on the adsorption of uranium(VI) by Amberlite IRA-910 resin. The adsorption process has been investigated as a function of adsorbate concentration, solution acidity, contact time, adsorbent dosage, and temperature. The experiments were preformed in batch mode, where uranium initial concentration on the solution samples were 185.5, 277.6 and 456.8 (mg/lit), sulfuric acid concentration range was 0.02-9 (mol/lit) and sorbent dosages were 0.2, 0.3 and 0.5 g. Equilibrium isotherm data were analyzed using Freundlich and Dubinin-Radushkevich isotherm models. The results showed that the adsorption process was well described by Freundlich... 

    Recovery of Uranium(VI) from UCF Waste by Selective Transportacross Aliquid Membrane

    , M.Sc. Thesis Sharif University of Technology Soltani Behrouz, Masoud (Author) ; Samadfam, Mohammad (Supervisor) ; Fasihi, Javad (Supervisor)
    Due to environmental and economical impacts, recovery of the uranium from nuclear wastes is of continuing interest.This work reports the separation of uranyl ionusing transport technique through chloroform liquid membrane containing a mixture of DBDA15C4 and oleic acidas cooperative carrier.The pH of the feed phase (10-4 M of UO22+) was adjusted with nitric acid and acetic acid/NaOH for pHrange of 2-6.The receiving phase was hydrochloric acid 1M.The organic phase was chloroform which includesthe carrier DBDA15C4 (0.0001 M) and also the oleic acid (0.015M).The results showed that the transport increased with increasing pH and reached to maximumat pH of 5.Maximum cooperative effect of oleic... 

    Removal of Fluorine from radioactive solid waste of Esfahan Uranium Conversion Facility

    , M.Sc. Thesis Sharif University of Technology Gerami, Vahid (Author) ; Samadfam, Mohammad (Supervisor) ; Khanchi, Alireza (Supervisor) ; Gasemi, Hosein (Co-Advisor)
    Uranium is the most important element in the nuclear fuel cycle. Recovery of uranium from waste produced at every stage of the fuel cycle is not only economically important, but also environmentally important. In the production phase of uranium hexafluoride, certain amount of solid waste is produced in the bottom of the fluorination reactor. In order to extract the uranium from this waste, we have to eliminate the fluorine contained in the waste. This is because the fluorine forms strong complex with uranyl ions during the extraction process, and prevents from efficient extraction of uranium. In the current thesis؛ first, we examined the characteristics of the waste ...