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The Anodic Dissolution Of Uranium Dioxide 2 In Carbonate Solutions
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Book Synopsis The Anodic Dissolution of Uranium Dioxide. 2. In Carbonate Solutions by :
Download or read book The Anodic Dissolution of Uranium Dioxide. 2. In Carbonate Solutions written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The anodic dissolution of uranium dioxide in alkaline carbonate solutions has been studied. Steady-state potentiostatic and cyclic voltammetric measurements have been shown to be consistent with a mechanism that involves a rate-determining two-electron transfer reaction. The presence of insulating uranium(VI) films on the surface at high anodic potentials has been confirmed by the use of ring-disc electrode measurements and characterized by X-ray-diffraction analyses. The dissolution behaviour of the films has been characterized and compared with that of samples of synthetic uranium trioxide and uranyl carbonate.
Book Synopsis A Potentiostatic Study of the Anodic Dissolution of Uranium Dioxide in Aqueous Solutions by : MJ. Nicol
Download or read book A Potentiostatic Study of the Anodic Dissolution of Uranium Dioxide in Aqueous Solutions written by MJ. Nicol and published by . This book was released on 1972 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anodic dissolution of uranium dioxide is shown to occur as a two-electron process with a current efficiency of 100 per cent in both acidic perchlorate and alkaline carbonate solutions. The effects, on the anodic dissolution process, of pH, temperature, and the various anions known to be present in commercial leaching solutions, were studied by the use of stationery potentiostatic measurements. The effects observed are interpreted in terms of the nature and properties of both the uranium dioxide surface and the primary products of oxidation.
Book Synopsis Kinetics of the Dissolution of Uranium Dioxide in Carbonate-bicarbonate Solutions by : W. E. Schortmann
Download or read book Kinetics of the Dissolution of Uranium Dioxide in Carbonate-bicarbonate Solutions written by W. E. Schortmann and published by . This book was released on 1958 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Anodic Dissolution of UO↓2 in Slightly Alkaline Sodium Perchlorate Solutions by : S. Sunder
Download or read book Anodic Dissolution of UO↓2 in Slightly Alkaline Sodium Perchlorate Solutions written by S. Sunder and published by Pinewa, Man. : Whiteshell Laboratories. This book was released on 1996 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters by :
Download or read book Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters written by and published by . This book was released on 1904 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The anodic dissolution of UO$\sb2$ has been studied in NaClO$\sb4$ NaCl, Standard Canadian Shield Saline Solution (SCSSS) and SCSSS + HCO$\sb3\sp-$ solutions using potentiostatic and cyclic voltammetry techniques. Under potentiostatic conditions two oxidation/dissolution regions were observed. Over the anodic potential range 0 1V $\leq$ E $\leq$ 0.425V (vs. SCE) currents decayed continuously due to the formation of oxidized surface films. The UO$\sb2$ surface was determined to be blocked by a thin film of UO$\sb{2.33}$ and a deposited U$\sp{\rm VI}$ solid distributed uniformly over the surface. In NaClO$\sb4$ and NaCl solutions, the U$\sp{\rm VI}$ solid was a UO$\sb3{\cdot}2$H$\sb2$O deposit. In SCSSS and SCSSS + HCO$\sb3\sp-$ solutions, calcium and silicon ions became incorporated into the U$\sp{\rm VI}$ solid. Over the anodic potential range 0.425V $\leq$ E $\leq$ 0.55V (vs. SCE), the rate of UO$\sb{2.33}$ film formation was equal to the rate of its oxidative dissolution as UO$\sb2\sp{2+}$ (i.e. steady state conditions). In all four solutions, the dissolution/hydrolysis/acidification rate was sufficiently rapid to establish local acidity at high anodic potentials. This local acidity lead to an increase in local solubility of U$\sp{\rm VI}$ which was then transported away from the dissolution sites as UO$\sb2\sp{2+}$ rather than deposited as a U$\sp{\rm VI}$ solid. After anodic oxidation in SCSSS, steady state was established at a higher potential than that for NaClO$\sb4$ and NaCl which indicated that alcium/silicon containing U$\sp{\rm VI}$ phases blocked the oxidative dissolution process until a higher potential was reached. Conversely, after anodic oxidation in SCSSS + HCO$\sb3\sp-$ steady state was established at a lower potential than that for NaClO$\sb4$ and NaCl which indicated that HCO$\sb3\sp-$ accelerated the oxidative dissolution process despite the presence of calcium and silicon ions. (Abstract shortened by UMI.).
Book Synopsis Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters by : Jodi L. M. Luht
Download or read book Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters written by Jodi L. M. Luht and published by . This book was released on 1998 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters by : Jodi L. M. Luht
Download or read book Anodic Dissolution of Uranium Dioxide in Simple Electrolyte Solutions and Simulated Groundwaters written by Jodi L. M. Luht and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Anodic Dissolution of Uranium Dioxide. 1. In Perchlorate Solutions by :
Download or read book The Anodic Dissolution of Uranium Dioxide. 1. In Perchlorate Solutions written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The anodic dissolution of uranium dioxide in perchlorate solution has been studied. Steady-state potentiostatic and cyclic voltammetric measurements have been shown to be consistent with a mechanism that involves successive electron-transfer reactions. The presence of insulating uranium (VI) films on the surface at high anodic potentials has been confirmed by measurements with ring-disc electrodes. A comparative study of the behaviour of several samples of differing stoichiometry, crystallinity and porosity has revealed the existence of considerable solid-state effects, the origin of which is not clear.
Book Synopsis Electrochemical Model for the Leaching of Uranium Dioxide. 2. Alkaline Carbonate Media by :
Download or read book Electrochemical Model for the Leaching of Uranium Dioxide. 2. Alkaline Carbonate Media written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dissolution of uranium dioxide in the presence of various oxidants in alkaline carbonate solutions has been shown to be electrochemical in nature. A mathematical description of the dissolution process in terms of the electrochemical model has been verified and used to explain the observed dependence of the dissolution rate on the oxidant concentration. The effects of various parameters, such as pH, carbonate concentration, temperature and the presence of various anions in solution, have been rationalized in terms of the electrochemical model.
Download or read book U Uranium written by and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume Uranium C5 covers the physical properties of U0 - the production 2 and preparation of U0 were already treated in Uranium C4, whereas the chemical proper 2 ties will be the subject of the forthcoming part C6. U0 is the most important chemical compound in all aspects of nuclear technology. 2 It is and will be for the foreseeable future the fuel for all light and heavy water reactors as well as (in the mixed crystal with Pu0 ) for the fast breeder reactors. Therefore, the 2 nuclear engineer has to understand the behavior of U0 under all conditions existing during 2 operational (and possibly failure) states of a nuclear reactor, e. g. , not only in the solid state but also to some extent in the liquid and gaseous states. Besides high scientific interest in the sometimes unique or unusual properties, e. g. , at low temperatures, a lot of data and physical properties which are critical for its use as a nuclear fuel have been determined more or less accurately. Creep, swelling, irradiation densification, and fission gas behavior in the fuel are properties which have been evaluated up to the high temperatu res (near the melting point) which may exist in U0 fuel due to its low thermal conductivity. 2 Besides these more technical data there have been accumulated a lot of important physical data, e. g.
Book Synopsis Dissolution of Uranium Dioxide Microspheres in Carbonate and Hydrogen Peroxide Solutions by : Timothy G. Adams
Download or read book Dissolution of Uranium Dioxide Microspheres in Carbonate and Hydrogen Peroxide Solutions written by Timothy G. Adams and published by . This book was released on 2013 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Uranium dioxide has been used in industry both as a fuel for power reactors and as a target for the production of radioisotopes. One of the most important radioisotopes produced using these targets is molybdenum-99 (Mo-99, 65.94hr half-life), which is the parent isotope to technetium-99m (Tc-99m, 6.01hr half-life), a radioisotope used in 70% of diagnostic medical isotope procedures performed in the United States of America. [1] [2] Molybdenum-99, produced by either the thermal neutron fission of uranium-235 in nuclear reactors or by neutron activation of molybdenum-98, is purified, packaged, and shipped to hospitals worldwide. The maximal activity of Tc-99m is reached in 22.9hrs, so it can be milked from the parent Mo-99 repeatedly. Mo-99 is one of many fission products generated during the thermal neutron fission of uranium-235. For production of Mo-99, irradiation targets based on metallic uranium, uranium alloys, or uranium dioxide are produced. After neutron irradiation in a reactor, the uranium target must first be dissolved in a suitable medium. This has traditionally been done using boiling nitric acid solutions. In literature and in industry, the use of alkaline solutions, specifically carbonate salt solutions combined with hydrogen peroxide, are being explored as an alternative to the nitric acid based dissolution process. The carbonate-peroxide dissolution scheme has several advantages over traditional nitric acid dissolutions including less damage to equipment during operation and smaller volumes of waste produced during process. This thesis research work explores the initial dissolution rates of uranium dioxide in carbonate medium containing hydrogen peroxide. Effect of three different counter cations- ammonium, sodium, and potassium - on the dissolution behavior of uranium was investigated. The kinetic factors of dissolution, activation energy, frequency factor, and reaction order with respect to both the carbonate salt and hydrogen peroxide were found for each of these systems. Information in this thesis is organized into six chapters and list of cited literature sources.
Book Synopsis Anodic dissolution of uo2 in slightly alkaline sodium perchlorate solutions by : S. Sunder
Download or read book Anodic dissolution of uo2 in slightly alkaline sodium perchlorate solutions written by S. Sunder and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anodic dissolution of uo2 has been studied in aqueous sodium perchlorate solutions at ph approximately 9.5. under potentiostatic conditions two distinct regions of oxidation/dissolution behaviour were observed. in the potential (e) range 0.100 v approximately e approximately 0.350 v (vs. sce) currents decayed continuously with time due to the formation of oxidized surface films which gradually blocked further oxidation of the electrode. steady-state currents were not achieved even after 24 hours. on the basis of anodic and cathodic charges (q sub(a), q sub(c) respectively) obtained by integration of the anodic current-time plots (q sub(a)) and cathodic potential scans to reduce accumulated oxidized surface films (q sub(c)), it was shown that approximately 90% of the anodic oxidation current went to produce these films. for e approximately 0.350 v, steady-state currrents were obtained and measurements of q sub(a) and q sub(c) showed the majority of the current went to produce soluble species. the film blocking anodic dissolution appeared to be either uo sub(2.67) or, more probably, uo3 middle dot 2h2o located primarily at grain boundaries. it is proposed that, at the higher potentials, rapid oxidation and dissolution followed by the hydrolysis of dissolved uranyl species leads to the development of acidic conditions in the grain boundaries. at these lower ph values the uo3 middle dot 2h2o is soluble and therefore does not accumulate. alternatively, if this oxide has been formed by prior oxidation at a lower potential, the formation of protons on oxidizing at e > approximately 0.350v causes its redissolution, allowing the current to rise to a steady-state value. on the basis of tafel slopes, an attempt was made to demonstrate that the observed behaviour was consistent with dissolution under acidic conditions. this analysis was only partially successful.
Book Synopsis Hydrometallurgy in Extraction Processes, Volume I by : T.K. Mukherjee
Download or read book Hydrometallurgy in Extraction Processes, Volume I written by T.K. Mukherjee and published by Routledge. This book was released on 2019-01-22 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This two-volume set provides a full account of hydrometallurgy. Filled with illustrations and tables, this work covers the flow of source material from the mined or concentrate state to the finished product. It also highlights ion exchange, carbon adsorption and solvent extraction processes for solution purification and concentration. The extensive
Book Synopsis The mechanism of the anodic dissolution of uranium dioxide by : M. J. Nicol
Download or read book The mechanism of the anodic dissolution of uranium dioxide written by M. J. Nicol and published by . This book was released on 1973 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Unrestricted Mintek Publications by :
Download or read book Unrestricted Mintek Publications written by and published by . This book was released on 1966 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Kinetics of Dissolution of Beta-uranium Trioxide in Acid and Carbonate Solutions. Part 2 - Carbonate Solutions by :
Download or read book The Kinetics of Dissolution of Beta-uranium Trioxide in Acid and Carbonate Solutions. Part 2 - Carbonate Solutions written by and published by . This book was released on 1976 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The kinetics of dissolution of beta-uranium trioxide in carbonate solutions have been studied as functions of stirring rate, carbonate concentration, hydrogen ion concentration, various cations in solutions and temperature. The salient features are that the dissolution rates were: (i) Independent of stirring rate. (ii) Dependent on the 1.0 order of the carbonate concentration. (iii) Linearly decreasing functions of pH. (iv) Inhibited by cations. The rate decreased in the order Na+>NH4+>Cs+>K+. (v) Arrhenius functions of temperature, with an activation energy of about 15 kcal per mol. The observed kinetic data has been rationalised in terms of a Charge Transfer mechanism, namely, the transfer of carbonatouranyl species and protonated oxide species across the electrochemical potential barrier at the solid-solution phase boundary is the rate-determining step during the dissolution reaction.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt:
